[patch] mptcp_against_3.11_v2.patch

mptcp_patch_against_3.11.x_v2.patch (text/plain), 448.59 KB, created by David Heidelberg (okias) on 2013-10-06 16:35:26 UTC

 From: David Heidelberger <david.heidelberger at ixit.cz>
 Subject: [PATCH v2] gentoo-sources: add MultiPath TCP (mptcp support)

 v2: fix according by changes introduced in 3.11.0 [ commit 351638e7deeed2ec8ce451b53d33921b3da68f83 ] to prevent BUG
 	in mptcp_pm_netdev_event and mptcp_pm_v6_netdev_event by changing:
		struct net_device *dev = ptr => struct net_device *dev = netdev_notifier_info_to_dev(ptr)
---
diff -Naur a/drivers/infiniband/hw/cxgb4/cm.c b/drivers/infiniband/hw/cxgb4/cm.c
--- a/drivers/infiniband/hw/cxgb4/cm.c	2013-09-02 22:46:10.000000000 +0200
+++ b/drivers/infiniband/hw/cxgb4/cm.c	2013-10-06 18:26:03.988872534 +0200
@@ -2921,7 +2921,7 @@
 	 */
 	memset(&tmp_opt, 0, sizeof(tmp_opt));
 	tcp_clear_options(&tmp_opt);
-	tcp_parse_options(skb, &tmp_opt, 0, NULL);
+	tcp_parse_options(skb, &tmp_opt, NULL, 0, NULL);
 
 	req = (struct cpl_pass_accept_req *)__skb_push(skb, sizeof(*req));
 	memset(req, 0, sizeof(*req));
diff -Naur a/include/linux/tcp.h b/include/linux/tcp.h
--- a/include/linux/tcp.h	2013-09-02 22:46:10.000000000 +0200
+++ b/include/linux/tcp.h	2013-10-06 18:26:04.015872194 +0200
@@ -72,6 +72,45 @@
 	u32	end_seq;
 };
 
+struct tcp_out_options {
+	u16	options;	/* bit field of OPTION_* */
+	u8	ws;		/* window scale, 0 to disable */
+	u8	num_sack_blocks;/* number of SACK blocks to include */
+	u8	hash_size;	/* bytes in hash_location */
+	u16	mss;		/* 0 to disable */
+	__u8	*hash_location;	/* temporary pointer, overloaded */
+	__u32	tsval, tsecr;	/* need to include OPTION_TS */
+	struct tcp_fastopen_cookie *fastopen_cookie;	/* Fast open cookie */
+#ifdef CONFIG_MPTCP
+	u16	mptcp_options;	/* bit field of MPTCP related OPTION_* */
+	__sum16	dss_csum;	/* Overloaded field: dss-checksum required
+				 * (for SYN-packets)? Or dss-csum itself */
+
+	__u32	data_seq;	/* data sequence number, for MPTCP */
+	__u32	data_ack;	/* data ack, for MPTCP */
+
+	union {
+		struct {
+			__u64	sender_key;	/* sender's key for mptcp */
+			__u64	receiver_key;	/* receiver's key for mptcp */
+		} mp_capable;
+
+		struct {
+			__u64	sender_truncated_mac;
+			__u32	sender_nonce;
+					/* random number of the sender */
+			__u32	token;	/* token for mptcp */
+		} mp_join_syns;
+	};
+
+	struct mptcp_loc4 *addr4;/* v4 addresses for MPTCP */
+	struct mptcp_loc6 *addr6;/* v6 addresses for MPTCP */
+
+	u16	remove_addrs;	/* list of address id */
+	u8	addr_id;	/* address id */
+#endif /* CONFIG_MPTCP */
+};
+
 /*These are used to set the sack_ok field in struct tcp_options_received */
 #define TCP_SACK_SEEN     (1 << 0)   /*1 = peer is SACK capable, */
 #define TCP_FACK_ENABLED  (1 << 1)   /*1 = FACK is enabled locally*/
@@ -95,6 +134,9 @@
 	u16	mss_clamp;	/* Maximal mss, negotiated at connection setup */
 };
 
+struct mptcp_cb;
+struct mptcp_tcp_sock;
+
 static inline void tcp_clear_options(struct tcp_options_received *rx_opt)
 {
 	rx_opt->tstamp_ok = rx_opt->sack_ok = 0;
@@ -124,6 +166,7 @@
 						  * FastOpen it's the seq#
 						  * after data-in-SYN.
 						  */
+	u8				saw_mpc:1;
 };
 
 static inline struct tcp_request_sock *tcp_rsk(const struct request_sock *req)
@@ -320,6 +363,35 @@
 	 * socket. Used to retransmit SYNACKs etc.
 	 */
 	struct request_sock *fastopen_rsk;
+
+
+	struct mptcp_cb		*mpcb;
+	struct sock		*meta_sk;
+	/* We keep these flags even if CONFIG_MPTCP is not checked, because
+	 * it allows checking MPTCP capability just by checking the mpc flag,
+	 * rather than adding ifdefs everywhere.
+	 */
+	u16     mpc:1,          /* Other end is multipath capable */
+		inside_tk_table:1, /* Is the tcp_sock inside the token-table? */
+		send_mp_fclose:1,
+		request_mptcp:1, /* Did we send out an MP_CAPABLE?
+				  * (this speeds up mptcp_doit() in tcp_recvmsg)
+				  */
+		pf:1, /* Potentially Failed state: when this flag is set, we
+		       * stop using the subflow
+		       */
+		mp_killed:1, /* Killed with a tcp_done in mptcp? */
+		mptcp_add_addr_ack:1,	/* Tell tcp_send_ack to return in case
+					 * alloc_skb fails. */
+		was_meta_sk:1,	/* This was a meta sk (in case of reuse) */
+		close_it:1,	/* Must close socket in mptcp_data_ready? */
+		closing:1;
+	struct mptcp_tcp_sock *mptcp;
+#ifdef CONFIG_MPTCP
+	struct hlist_nulls_node tk_table;
+	u32		mptcp_loc_token;
+	u64		mptcp_loc_key;
+#endif /* CONFIG_MPTCP */
 };
 
 enum tsq_flags {
@@ -349,6 +421,7 @@
 #ifdef CONFIG_TCP_MD5SIG
 	struct tcp_md5sig_key	  *tw_md5_key;
 #endif
+	struct mptcp_tw		  *mptcp_tw;
 };
 
 static inline struct tcp_timewait_sock *tcp_twsk(const struct sock *sk)
diff -Naur a/include/net/inet6_connection_sock.h b/include/net/inet6_connection_sock.h
--- a/include/net/inet6_connection_sock.h	2013-09-02 22:46:10.000000000 +0200
+++ b/include/net/inet6_connection_sock.h	2013-10-06 18:26:04.026872056 +0200
@@ -25,6 +25,8 @@
 extern int inet6_csk_bind_conflict(const struct sock *sk,
 				   const struct inet_bind_bucket *tb, bool relax);
 
+extern u32 inet6_synq_hash(const struct in6_addr *raddr, const __be16 rport,
+			   const u32 rnd, const u32 synq_hsize);
 extern struct dst_entry* inet6_csk_route_req(struct sock *sk,
 					     struct flowi6 *fl6,
 					     const struct request_sock *req);
diff -Naur a/include/net/inet_common.h b/include/net/inet_common.h
--- a/include/net/inet_common.h	2013-09-02 22:46:10.000000000 +0200
+++ b/include/net/inet_common.h	2013-10-06 18:26:04.029872018 +0200
@@ -1,6 +1,8 @@
 #ifndef _INET_COMMON_H
 #define _INET_COMMON_H
 
+#include <net/sock.h>
+
 extern const struct proto_ops inet_stream_ops;
 extern const struct proto_ops inet_dgram_ops;
 
@@ -13,6 +15,10 @@
 struct sockaddr;
 struct socket;
 
+extern int inet_create(struct net *net, struct socket *sock, int protocol,
+		       int kern);
+extern int inet6_create(struct net *net, struct socket *sock, int protocol,
+			int kern);
 extern int inet_release(struct socket *sock);
 extern int inet_stream_connect(struct socket *sock, struct sockaddr *uaddr,
 			       int addr_len, int flags);
diff -Naur a/include/net/inet_connection_sock.h b/include/net/inet_connection_sock.h
--- a/include/net/inet_connection_sock.h	2013-09-02 22:46:10.000000000 +0200
+++ b/include/net/inet_connection_sock.h	2013-10-06 18:26:04.069871515 +0200
@@ -243,6 +243,8 @@
 
 extern struct sock *inet_csk_accept(struct sock *sk, int flags, int *err);
 
+extern u32 inet_synq_hash(const __be32 raddr, const __be16 rport, const u32 rnd,
+			  const u32 synq_hsize);
 extern struct request_sock *inet_csk_search_req(const struct sock *sk,
 						struct request_sock ***prevp,
 						const __be16 rport,
diff -Naur a/include/net/mptcp.h b/include/net/mptcp.h
--- a/include/net/mptcp.h	1970-01-01 01:00:00.000000000 +0100
+++ b/include/net/mptcp.h	2013-10-06 18:26:04.071871490 +0200
@@ -0,0 +1,1403 @@
+/*
+ *	MPTCP implementation
+ *
+ *	Initial Design & Implementation:
+ *	Sébastien Barré <[e-mail]>
+ *
+ *	Current Maintainer & Author:
+ *	Christoph Paasch <[e-mail]>
+ *
+ *	Additional authors:
+ *	Jaakko Korkeaniemi <[e-mail]>
+ *	Gregory Detal <[e-mail]>
+ *	Fabien Duchêne <[e-mail]>
+ *	Andreas Seelinger <[e-mail]>
+ *	Lavkesh Lahngir <[e-mail]>
+ *	Andreas Ripke <[e-mail]>
+ *	Vlad Dogaru <[e-mail]>
+ *	Octavian Purdila <[e-mail]>
+ *	John Ronan <[e-mail]>
+ *	Catalin Nicutar <[e-mail]>
+ *	Brandon Heller <[e-mail]>
+ *
+ *
+ *	This program is free software; you can redistribute it and/or
+ *      modify it under the terms of the GNU General Public License
+ *      as published by the Free Software Foundation; either version
+ *      2 of the License, or (at your option) any later version.
+ */
+
+#ifndef _MPTCP_H
+#define _MPTCP_H
+
+#include <linux/inetdevice.h>
+#include <linux/ipv6.h>
+#include <linux/list.h>
+#include <linux/net.h>
+#include <linux/skbuff.h>
+#include <linux/socket.h>
+#include <linux/tcp.h>
+#include <linux/kernel.h>
+
+#include <asm/byteorder.h>
+#include <asm/unaligned.h>
+#include <crypto/hash.h>
+#include <net/mptcp_pm.h>
+#include <net/tcp.h>
+
+#if defined(__LITTLE_ENDIAN_BITFIELD)
+	#define ntohll(x)  be64_to_cpu(x)
+	#define htonll(x)  cpu_to_be64(x)
+#elif defined(__BIG_ENDIAN_BITFIELD)
+	#define ntohll(x) (x)
+	#define htonll(x) (x)
+#endif
+
+/* is seq1 < seq2 ? */
+static inline int before64(const u64 seq1, const u64 seq2)
+{
+	return (s64)(seq1 - seq2) < 0;
+}
+
+/* is seq1 > seq2 ? */
+#define after64(seq1, seq2)	before64(seq2, seq1)
+
+struct mptcp_request_sock {
+	struct tcp_request_sock		req;
+	struct mptcp_cb			*mpcb;
+	/* Collision list in the tuple hashtable. We need to find
+	 * the req sock when receiving the third msg of the 3-way handshake,
+	 * since that one does not contain the token. If this makes
+	 * the request sock too long, we can use kmalloc'ed specific entries for
+	 * that tuple hashtable. At the moment, though, I extend the
+	 * request_sock.
+	 */
+	struct list_head		collide_tuple;
+	struct hlist_nulls_node		collide_tk;
+	u32				mptcp_rem_nonce;
+	u32				mptcp_loc_token;
+	u64				mptcp_loc_key;
+	u64				mptcp_rem_key;
+	u64				mptcp_hash_tmac;
+	u32				mptcp_loc_nonce;
+	__u8				rem_id; /* Address-id in the MP_JOIN */
+	u8				dss_csum:1,
+					low_prio:1;
+};
+
+static inline
+struct mptcp_request_sock *mptcp_rsk(const struct request_sock *req)
+{
+	return (struct mptcp_request_sock *)req;
+}
+
+static inline
+struct request_sock *rev_mptcp_rsk(const struct mptcp_request_sock *req)
+{
+	return (struct request_sock *)req;
+}
+
+struct mptcp_options_received {
+	u16	saw_mpc:1,
+		dss_csum:1,
+		drop_me:1,
+
+		is_mp_join:1,
+		join_ack:1,
+
+		saw_low_prio:2, /* 0x1 - low-prio set for this subflow
+				 * 0x2 - low-prio set for another subflow
+				 */
+		low_prio:1,
+
+		saw_add_addr:2, /* Saw at least one add_addr option:
+				 * 0x1: IPv4 - 0x2: IPv6
+				 */
+		more_add_addr:1, /* Saw one more add-addr. */
+
+		saw_rem_addr:1, /* Saw at least one rem_addr option */
+		more_rem_addr:1, /* Saw one more rem-addr. */
+
+		mp_fail:1,
+		mp_fclose:1;
+	u8	rem_id;		/* Address-id in the MP_JOIN */
+	u8	prio_addr_id;	/* Address-id in the MP_PRIO */
+
+	const unsigned char *add_addr_ptr; /* Pointer to add-address option */
+	const unsigned char *rem_addr_ptr; /* Pointer to rem-address option */
+
+	u32	data_ack;
+	u32	data_seq;
+	u16	data_len;
+
+	u32	mptcp_rem_token;/* Remote token */
+
+	/* Key inside the option (from mp_capable or fast_close) */
+	u64	mptcp_key;
+
+	u32	mptcp_recv_nonce;
+	u64	mptcp_recv_tmac;
+	u8	mptcp_recv_mac[20];
+};
+
+struct mptcp_tcp_sock {
+	struct tcp_sock	*next;		/* Next subflow socket */
+	struct mptcp_options_received rx_opt;
+
+	 /* Those three fields record the current mapping */
+	u64	map_data_seq;
+	u32	map_subseq;
+	u16	map_data_len;
+	u16	slave_sk:1,
+		nonce_set:1, /* Is the nonce set? (in order to support 0-nonce) */
+		fully_established:1,
+		establish_increased:1,
+		second_packet:1,
+		attached:1,
+		send_mp_fail:1,
+		include_mpc:1,
+		mapping_present:1,
+		map_data_fin:1,
+		low_prio:1, /* use this socket as backup */
+		rcv_low_prio:1, /* Peer sent low-prio option to us */
+		send_mp_prio:1, /* Trigger to send mp_prio on this socket */
+		pre_established:1; /* State between sending 3rd ACK and
+				    * receiving the fourth ack of new subflows.
+				    */
+
+	/* isn: needed to translate abs to relative subflow seqnums */
+	u32	snt_isn;
+	u32	rcv_isn;
+	u32	last_data_seq;
+	u8	path_index;
+	u8	add_addr4; /* bit-field of addrs not yet sent to our peer */
+	u8	add_addr6;
+	u8	rem_id;
+
+	u32	last_rbuf_opti;	/* Timestamp of last rbuf optimization */
+	unsigned int sent_pkts;
+
+	struct sk_buff  *shortcut_ofoqueue; /* Shortcut to the current modified
+					     * skb in the ofo-queue.
+					     */
+
+	int	init_rcv_wnd;
+	u32	infinite_cutoff_seq;
+	struct delayed_work work;
+	u32	mptcp_loc_nonce;
+	struct tcp_sock *tp; /* Where is my daddy? */
+	u32	last_end_data_seq;
+
+	/* MP_JOIN subflow: timer for retransmitting the 3rd ack */
+	struct timer_list mptcp_ack_timer;
+
+	/* HMAC of the third ack */
+	char sender_mac[20];
+};
+
+struct mptcp_tw {
+	struct list_head list;
+	u64 loc_key;
+	u64 rcv_nxt;
+	struct mptcp_cb __rcu *mpcb;
+	u8 meta_tw:1,
+	   in_list:1;
+};
+
+struct mptcp_cb {
+	struct sock *meta_sk;
+
+	/* list of sockets in this multipath connection */
+	struct tcp_sock *connection_list;
+
+	spinlock_t	 tw_lock;
+	struct list_head tw_list;
+	unsigned char	 mptw_state;
+
+	atomic_t	refcnt;
+
+	/* High-order bits of 64-bit sequence numbers */
+	u32 snd_high_order[2];
+	u32 rcv_high_order[2];
+
+	u16	send_infinite_mapping:1,
+		in_time_wait:1,
+		list_rcvd:1, /* XXX TO REMOVE */
+		dss_csum:1,
+		server_side:1,
+		infinite_mapping_rcv:1,
+		infinite_mapping_snd:1,
+		dfin_combined:1,   /* Was the DFIN combined with subflow-fin? */
+		passive_close:1,
+		snd_hiseq_index:1, /* Index in snd_high_order of snd_nxt */
+		rcv_hiseq_index:1; /* Index in rcv_high_order of rcv_nxt */
+
+	/* socket count in this connection */
+	u8 cnt_subflows;
+	u8 cnt_established;
+
+	u32 noneligible;	/* Path mask of temporarily non
+				 * eligible subflows by the scheduler
+				 */
+
+	struct sk_buff_head reinject_queue;
+
+	u16 remove_addrs;
+
+	u8 dfin_path_index;
+	/* Worker struct for subflow establishment */
+	struct work_struct subflow_work;
+	struct delayed_work subflow_retry_work;
+	/* Worker to handle interface/address changes if socket is owned */
+	struct work_struct address_work;
+	/* Mutex needed, because otherwise mptcp_close will complain that the
+	 * socket is owned by the user.
+	 * E.g., mptcp_sub_close_wq is taking the meta-lock.
+	 */
+	struct mutex mutex;
+
+	/* Master socket, also part of the connection_list, this
+	 * socket is the one that the application sees.
+	 */
+	struct sock *master_sk;
+
+	u64	csum_cutoff_seq;
+
+	__u64	mptcp_loc_key;
+	__u32	mptcp_loc_token;
+	__u64	mptcp_rem_key;
+	__u32	mptcp_rem_token;
+
+	/* Create a new subflow - necessary because the meta-sk may be IPv4, but
+	 * the new subflow can be IPv6
+	 */
+	struct sock *(*syn_recv_sock)(struct sock *sk, struct sk_buff *skb,
+				      struct request_sock *req,
+				      struct dst_entry *dst);
+
+	/* Local addresses */
+	struct mptcp_loc4 locaddr4[MPTCP_MAX_ADDR];
+	u8 loc4_bits; /* Bitfield indicating which of the above addrs are set */
+	u8 next_v4_index;
+
+	struct mptcp_loc6 locaddr6[MPTCP_MAX_ADDR];
+	u8 loc6_bits;
+	u8 next_v6_index;
+
+	/* Remove addresses */
+	struct mptcp_rem4 remaddr4[MPTCP_MAX_ADDR];
+	u8 rem4_bits;
+
+	struct mptcp_rem6 remaddr6[MPTCP_MAX_ADDR];
+	u8 rem6_bits;
+
+	u32 path_index_bits;
+	/* Next pi to pick up in case a new path becomes available */
+	u8 next_path_index;
+
+	/* Original snd/rcvbuf of the initial subflow.
+	 * Used for the new subflows on the server-side to allow correct
+	 * autotuning
+	 */
+	int orig_sk_rcvbuf;
+	int orig_sk_sndbuf;
+	u32 orig_window_clamp;
+};
+
+static inline int mptcp_pi_to_flag(int pi)
+{
+	return 1 << (pi - 1);
+}
+
+#define MPTCP_SUB_CAPABLE			0
+#define MPTCP_SUB_LEN_CAPABLE_SYN		12
+#define MPTCP_SUB_LEN_CAPABLE_SYN_ALIGN		12
+#define MPTCP_SUB_LEN_CAPABLE_ACK		20
+#define MPTCP_SUB_LEN_CAPABLE_ACK_ALIGN		20
+
+#define MPTCP_SUB_JOIN			1
+#define MPTCP_SUB_LEN_JOIN_SYN		12
+#define MPTCP_SUB_LEN_JOIN_SYN_ALIGN	12
+#define MPTCP_SUB_LEN_JOIN_SYNACK	16
+#define MPTCP_SUB_LEN_JOIN_SYNACK_ALIGN	16
+#define MPTCP_SUB_LEN_JOIN_ACK		24
+#define MPTCP_SUB_LEN_JOIN_ACK_ALIGN	24
+
+#define MPTCP_SUB_DSS		2
+#define MPTCP_SUB_LEN_DSS	4
+#define MPTCP_SUB_LEN_DSS_ALIGN	4
+
+/* Lengths for seq and ack are the ones without the generic MPTCP-option header,
+ * as they are part of the DSS-option.
+ * To get the total length, just add the different options together.
+ */
+#define MPTCP_SUB_LEN_SEQ	10
+#define MPTCP_SUB_LEN_SEQ_CSUM	12
+#define MPTCP_SUB_LEN_SEQ_ALIGN	12
+
+#define MPTCP_SUB_LEN_SEQ_64		14
+#define MPTCP_SUB_LEN_SEQ_CSUM_64	16
+#define MPTCP_SUB_LEN_SEQ_64_ALIGN	16
+
+#define MPTCP_SUB_LEN_ACK	4
+#define MPTCP_SUB_LEN_ACK_ALIGN	4
+
+#define MPTCP_SUB_LEN_ACK_64		8
+#define MPTCP_SUB_LEN_ACK_64_ALIGN	8
+
+/* This is the "default" option-length we will send out most often.
+ * MPTCP DSS-header
+ * 32-bit data sequence number
+ * 32-bit data ack
+ *
+ * It is necessary to calculate the effective MSS we will be using when
+ * sending data.
+ */
+#define MPTCP_SUB_LEN_DSM_ALIGN  (MPTCP_SUB_LEN_DSS_ALIGN +		\
+				  MPTCP_SUB_LEN_SEQ_ALIGN +		\
+				  MPTCP_SUB_LEN_ACK_ALIGN)
+
+#define MPTCP_SUB_ADD_ADDR		3
+#define MPTCP_SUB_LEN_ADD_ADDR4		8
+#define MPTCP_SUB_LEN_ADD_ADDR6		20
+#define MPTCP_SUB_LEN_ADD_ADDR4_ALIGN	8
+#define MPTCP_SUB_LEN_ADD_ADDR6_ALIGN	20
+
+#define MPTCP_SUB_REMOVE_ADDR	4
+#define MPTCP_SUB_LEN_REMOVE_ADDR	4
+
+#define MPTCP_SUB_PRIO		5
+#define MPTCP_SUB_LEN_PRIO	3
+#define MPTCP_SUB_LEN_PRIO_ADDR	4
+#define MPTCP_SUB_LEN_PRIO_ALIGN	4
+
+#define MPTCP_SUB_FAIL		6
+#define MPTCP_SUB_LEN_FAIL	12
+#define MPTCP_SUB_LEN_FAIL_ALIGN	12
+
+#define MPTCP_SUB_FCLOSE	7
+#define MPTCP_SUB_LEN_FCLOSE	12
+#define MPTCP_SUB_LEN_FCLOSE_ALIGN	12
+
+
+#define OPTION_MPTCP		(1 << 5)
+
+#ifdef CONFIG_MPTCP
+
+/* MPTCP options */
+#define OPTION_TYPE_SYN		(1 << 0)
+#define OPTION_TYPE_SYNACK	(1 << 1)
+#define OPTION_TYPE_ACK		(1 << 2)
+#define OPTION_MP_CAPABLE	(1 << 3)
+#define OPTION_DATA_ACK		(1 << 4)
+#define OPTION_ADD_ADDR		(1 << 5)
+#define OPTION_MP_JOIN		(1 << 6)
+#define OPTION_MP_FAIL		(1 << 7)
+#define OPTION_MP_FCLOSE	(1 << 8)
+#define OPTION_REMOVE_ADDR	(1 << 9)
+#define OPTION_MP_PRIO		(1 << 10)
+
+/* Used for checking if the mptcp initialization has been successful */
+extern bool mptcp_init_failed;
+
+struct mptcp_option {
+	__u8	kind;
+	__u8	len;
+#if defined(__LITTLE_ENDIAN_BITFIELD)
+	__u8	ver:4,
+		sub:4;
+#elif defined(__BIG_ENDIAN_BITFIELD)
+	__u8	sub:4,
+		ver:4;
+#else
+#error	"Adjust your <asm/byteorder.h> defines"
+#endif
+};
+
+struct mp_capable {
+	__u8	kind;
+	__u8	len;
+#if defined(__LITTLE_ENDIAN_BITFIELD)
+	__u8	ver:4,
+		sub:4;
+	__u8	h:1,
+		rsv:5,
+		b:1,
+		a:1;
+#elif defined(__BIG_ENDIAN_BITFIELD)
+	__u8	sub:4,
+		ver:4;
+	__u8	a:1,
+		b:1,
+		rsv:5,
+		h:1;
+#else
+#error	"Adjust your <asm/byteorder.h> defines"
+#endif
+	__u64	sender_key;
+	__u64	receiver_key;
+} __attribute__((__packed__));
+
+struct mp_join {
+	__u8	kind;
+	__u8	len;
+#if defined(__LITTLE_ENDIAN_BITFIELD)
+	__u8	b:1,
+		rsv:3,
+		sub:4;
+#elif defined(__BIG_ENDIAN_BITFIELD)
+	__u8	sub:4,
+		rsv:3,
+		b:1;
+#else
+#error	"Adjust your <asm/byteorder.h> defines"
+#endif
+	__u8	addr_id;
+	union {
+		struct {
+			u32	token;
+			u32	nonce;
+		} syn;
+		struct {
+			__u64	mac;
+			u32	nonce;
+		} synack;
+		struct {
+			__u8	mac[20];
+		} ack;
+	} u;
+} __attribute__((__packed__));
+
+struct mp_dss {
+	__u8	kind;
+	__u8	len;
+#if defined(__LITTLE_ENDIAN_BITFIELD)
+	__u16	rsv1:4,
+		sub:4,
+		A:1,
+		a:1,
+		M:1,
+		m:1,
+		F:1,
+		rsv2:3;
+#elif defined(__BIG_ENDIAN_BITFIELD)
+	__u16	sub:4,
+		rsv1:4,
+		rsv2:3,
+		F:1,
+		m:1,
+		M:1,
+		a:1,
+		A:1;
+#else
+#error	"Adjust your <asm/byteorder.h> defines"
+#endif
+};
+
+struct mp_add_addr {
+	__u8	kind;
+	__u8	len;
+#if defined(__LITTLE_ENDIAN_BITFIELD)
+	__u8	ipver:4,
+		sub:4;
+#elif defined(__BIG_ENDIAN_BITFIELD)
+	__u8	sub:4,
+		ipver:4;
+#else
+#error	"Adjust your <asm/byteorder.h> defines"
+#endif
+	__u8	addr_id;
+	union {
+		struct {
+			struct in_addr	addr;
+			__be16		port;
+		} v4;
+		struct {
+			struct in6_addr	addr;
+			__be16		port;
+		} v6;
+	} u;
+} __attribute__((__packed__));
+
+struct mp_remove_addr {
+	__u8	kind;
+	__u8	len;
+#if defined(__LITTLE_ENDIAN_BITFIELD)
+	__u8	rsv:4,
+		sub:4;
+#elif defined(__BIG_ENDIAN_BITFIELD)
+	__u8	sub:4,
+		rsv:4;
+#else
+#error "Adjust your <asm/byteorder.h> defines"
+#endif
+	/* list of addr_id */
+	__u8	addrs_id;
+};
+
+struct mp_fail {
+	__u8	kind;
+	__u8	len;
+#if defined(__LITTLE_ENDIAN_BITFIELD)
+	__u16	rsv1:4,
+		sub:4,
+		rsv2:8;
+#elif defined(__BIG_ENDIAN_BITFIELD)
+	__u16	sub:4,
+		rsv1:4,
+		rsv2:8;
+#else
+#error	"Adjust your <asm/byteorder.h> defines"
+#endif
+	__be64	data_seq;
+} __attribute__((__packed__));
+
+struct mp_fclose {
+	__u8	kind;
+	__u8	len;
+#if defined(__LITTLE_ENDIAN_BITFIELD)
+	__u16	rsv1:4,
+		sub:4,
+		rsv2:8;
+#elif defined(__BIG_ENDIAN_BITFIELD)
+	__u16	sub:4,
+		rsv1:4,
+		rsv2:8;
+#else
+#error	"Adjust your <asm/byteorder.h> defines"
+#endif
+	__u64	key;
+} __attribute__((__packed__));
+
+struct mp_prio {
+	__u8	kind;
+	__u8	len;
+#if defined(__LITTLE_ENDIAN_BITFIELD)
+	__u8	b:1,
+		rsv:3,
+		sub:4;
+#elif defined(__BIG_ENDIAN_BITFIELD)
+	__u8	sub:4,
+		rsv:3,
+		b:1;
+#else
+#error	"Adjust your <asm/byteorder.h> defines"
+#endif
+	__u8	addr_id;
+} __attribute__((__packed__));
+
+static inline int mptcp_sub_len_remove_addr(u16 bitfield)
+{
+	unsigned int c;
+	for (c = 0; bitfield; c++)
+		bitfield &= bitfield - 1;
+	return MPTCP_SUB_LEN_REMOVE_ADDR + c - 1;
+}
+
+static inline int mptcp_sub_len_remove_addr_align(u16 bitfield)
+{
+	return ALIGN(mptcp_sub_len_remove_addr(bitfield), 4);
+}
+
+static inline int mptcp_sub_len_dss(struct mp_dss *m, int csum)
+{
+	return 4 + m->A * (4 + m->a * 4) + m->M * (10 + m->m * 4 + csum * 2);
+}
+
+/* Default MSS for MPTCP
+ * All subflows will be using that MSS. If any subflow has a lower MSS, it is
+ * just not used. */
+#define MPTCP_MSS 1400
+#define MPTCP_SYN_RETRIES 3
+extern int sysctl_mptcp_ndiffports;
+extern int sysctl_mptcp_enabled;
+extern int sysctl_mptcp_checksum;
+extern int sysctl_mptcp_debug;
+extern int sysctl_mptcp_syn_retries;
+
+extern struct workqueue_struct *mptcp_wq;
+
+#define mptcp_debug(fmt, args...)					\
+	do {								\
+		if (unlikely(sysctl_mptcp_debug))			\
+			pr_err(__FILE__ ": " fmt, ##args);	\
+	} while (0)
+
+/* Iterates over all subflows */
+#define mptcp_for_each_tp(mpcb, tp)					\
+	for ((tp) = (mpcb)->connection_list; (tp); (tp) = (tp)->mptcp->next)
+
+#define mptcp_for_each_sk(mpcb, sk)					\
+	for ((sk) = (struct sock *)(mpcb)->connection_list;		\
+	     sk;							\
+	     sk = (struct sock *)tcp_sk(sk)->mptcp->next)
+
+#define mptcp_for_each_sk_safe(__mpcb, __sk, __temp)			\
+	for (__sk = (struct sock *)(__mpcb)->connection_list,		\
+	     __temp = __sk ? (struct sock *)tcp_sk(__sk)->mptcp->next : NULL; \
+	     __sk;							\
+	     __sk = __temp,						\
+	     __temp = __sk ? (struct sock *)tcp_sk(__sk)->mptcp->next : NULL)
+
+/* Iterates over all bit set to 1 in a bitset */
+#define mptcp_for_each_bit_set(b, i)					\
+	for (i = ffs(b) - 1; i >= 0; i = ffs(b >> (i + 1) << (i + 1)) - 1)
+
+#define mptcp_for_each_bit_unset(b, i)					\
+	mptcp_for_each_bit_set(~b, i)
+
+extern struct lock_class_key meta_key;
+extern struct lock_class_key meta_slock_key;
+extern u32 mptcp_secret[MD5_MESSAGE_BYTES / 4];
+
+/* This is needed to ensure that two subsequent key-generation result in
+ * different keys if the IPs and ports are the same.
+ */
+extern u32 mptcp_key_seed;
+
+void mptcp_data_ready(struct sock *sk, int bytes);
+void mptcp_write_space(struct sock *sk);
+
+void mptcp_add_meta_ofo_queue(struct sock *meta_sk, struct sk_buff *skb,
+			      struct sock *sk);
+void mptcp_ofo_queue(struct sock *meta_sk);
+void mptcp_purge_ofo_queue(struct tcp_sock *meta_tp);
+void mptcp_cleanup_rbuf(struct sock *meta_sk, int copied);
+int mptcp_alloc_mpcb(struct sock *master_sk, __u64 remote_key, u32 window);
+int mptcp_add_sock(struct sock *meta_sk, struct sock *sk, u8 rem_id, gfp_t flags);
+void mptcp_del_sock(struct sock *sk);
+void mptcp_update_metasocket(struct sock *sock, struct sock *meta_sk);
+void mptcp_reinject_data(struct sock *orig_sk, int clone_it);
+void mptcp_update_sndbuf(struct mptcp_cb *mpcb);
+struct sk_buff *mptcp_next_segment(struct sock *sk, int *reinject);
+void mptcp_send_fin(struct sock *meta_sk);
+void mptcp_send_active_reset(struct sock *meta_sk, gfp_t priority);
+int mptcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle,
+		     int push_one, gfp_t gfp);
+void mptcp_parse_options(const uint8_t *ptr, int opsize,
+			 struct tcp_options_received *opt_rx,
+			 struct mptcp_options_received *mopt,
+			 const struct sk_buff *skb);
+void mptcp_syn_options(struct sock *sk, struct tcp_out_options *opts,
+		       unsigned *remaining);
+void mptcp_synack_options(struct request_sock *req,
+			  struct tcp_out_options *opts,
+			  unsigned *remaining);
+void mptcp_established_options(struct sock *sk, struct sk_buff *skb,
+			       struct tcp_out_options *opts, unsigned *size);
+void mptcp_options_write(__be32 *ptr, struct tcp_sock *tp,
+			 struct tcp_out_options *opts,
+			 struct sk_buff *skb);
+void mptcp_close(struct sock *meta_sk, long timeout);
+int mptcp_doit(struct sock *sk);
+int mptcp_create_master_sk(struct sock *meta_sk, __u64 remote_key, u32 window);
+int mptcp_check_req_master(struct sock *sk, struct sock *child,
+			   struct request_sock *req,
+			   struct request_sock **prev,
+			   struct mptcp_options_received *mopt);
+struct sock *mptcp_check_req_child(struct sock *sk, struct sock *child,
+				   struct request_sock *req,
+				   struct request_sock **prev,
+				   struct mptcp_options_received *mopt);
+u32 __mptcp_select_window(struct sock *sk);
+void mptcp_select_initial_window(int *__space, __u32 *window_clamp,
+			         const struct sock *sk);
+unsigned int mptcp_current_mss(struct sock *meta_sk);
+int mptcp_select_size(const struct sock *meta_sk, bool sg);
+void mptcp_key_sha1(u64 key, u32 *token, u64 *idsn);
+void mptcp_hmac_sha1(u8 *key_1, u8 *key_2, u8 *rand_1, u8 *rand_2,
+		     u32 *hash_out);
+void mptcp_clean_rtx_infinite(struct sk_buff *skb, struct sock *sk);
+void mptcp_fin(struct sock *meta_sk);
+void mptcp_retransmit_timer(struct sock *meta_sk);
+int mptcp_write_wakeup(struct sock *meta_sk);
+void mptcp_sub_close_wq(struct work_struct *work);
+void mptcp_sub_close(struct sock *sk, unsigned long delay);
+struct sock *mptcp_select_ack_sock(const struct sock *meta_sk, int copied);
+void mptcp_fallback_meta_sk(struct sock *meta_sk);
+int mptcp_backlog_rcv(struct sock *meta_sk, struct sk_buff *skb);
+struct sock *mptcp_sk_clone(const struct sock *sk, int family, const gfp_t priority);
+void mptcp_ack_handler(unsigned long);
+void mptcp_set_keepalive(struct sock *sk, int val);
+int mptcp_check_rtt(const struct tcp_sock *tp, int time);
+int mptcp_check_snd_buf(const struct tcp_sock *tp);
+int mptcp_handle_options(struct sock *sk, const struct tcphdr *th, struct sk_buff *skb);
+void __init mptcp_init(void);
+int mptcp_trim_head(struct sock *sk, struct sk_buff *skb, u32 len);
+int mptcp_fragment(struct sock *sk, struct sk_buff *skb, u32 len,
+		   unsigned int mss_now, int reinject);
+int mptso_fragment(struct sock *sk, struct sk_buff *skb, unsigned int len,
+		   unsigned int mss_now, gfp_t gfp, int reinject);
+void mptcp_destroy_sock(struct sock *sk);
+int mptcp_rcv_synsent_state_process(struct sock *sk, struct sock **skptr,
+				    struct sk_buff *skb,
+				    struct mptcp_options_received *mopt);
+unsigned int mptcp_xmit_size_goal(struct sock *meta_sk, u32 mss_now,
+				  int large_allowed);
+int mptcp_time_wait(struct sock *sk, struct tcp_timewait_sock *tw);
+void mptcp_twsk_destructor(struct tcp_timewait_sock *tw);
+void mptcp_update_tw_socks(const struct tcp_sock *tp, int state);
+int mptcp_retransmit_skb(struct sock *meta_sk, struct sk_buff *skb);
+
+static inline bool mptcp_can_sendpage(struct sock *sk)
+{
+	struct sock *sk_it;
+
+	if (tcp_sk(sk)->mpcb->dss_csum)
+		return false;
+
+	mptcp_for_each_sk(tcp_sk(sk)->mpcb, sk_it) {
+		if (!(sk_it->sk_route_caps & NETIF_F_SG) ||
+		    !(sk_it->sk_route_caps & NETIF_F_ALL_CSUM))
+			return false;
+	}
+
+	return true;
+}
+
+static inline void mptcp_push_pending_frames(struct sock *meta_sk)
+{
+	if (mptcp_next_segment(meta_sk, NULL)) {
+		struct tcp_sock *tp = tcp_sk(meta_sk);
+
+		/* We don't care about the MSS, because it will be set in
+		 * mptcp_write_xmit.
+		 */
+		__tcp_push_pending_frames(meta_sk, 0, tp->nonagle);
+	}
+}
+
+static inline void mptcp_sub_force_close(struct sock *sk)
+{
+	/* The below tcp_done may have freed the socket, if he is already dead.
+	 * Thus, we are not allowed to access it afterwards. That's why
+	 * we have to store the dead-state in this local variable.
+	 */
+	int sock_is_dead = sock_flag(sk, SOCK_DEAD);
+
+	tcp_sk(sk)->mp_killed = 1;
+
+	if (sk->sk_state != TCP_CLOSE)
+		tcp_done(sk);
+
+	if (!sock_is_dead)
+		mptcp_sub_close(sk, 0);
+}
+
+static inline void mptcp_send_reset(struct sock *sk)
+{
+	tcp_send_active_reset(sk, GFP_ATOMIC);
+	mptcp_sub_force_close(sk);
+}
+
+static inline int mptcp_is_data_seq(const struct sk_buff *skb)
+{
+	return TCP_SKB_CB(skb)->mptcp_flags & MPTCPHDR_SEQ;
+}
+
+static inline int mptcp_is_data_fin(const struct sk_buff *skb)
+{
+	return mptcp_is_data_seq(skb) &&
+	       (TCP_SKB_CB(skb)->mptcp_flags & MPTCPHDR_FIN);
+}
+
+/* Is it a data-fin while in infinite mapping mode?
+ * In infinite mode, a subflow-fin is in fact a data-fin.
+ */
+static inline int mptcp_is_data_fin2(const struct sk_buff *skb,
+				     const struct tcp_sock *tp)
+{
+	return mptcp_is_data_fin(skb) ||
+	       (tp->mpcb->infinite_mapping_rcv && tcp_hdr(skb)->fin);
+}
+
+static inline void mptcp_skb_entail_init(const struct tcp_sock *tp,
+					 struct sk_buff *skb)
+{
+	if (tp->mpc)
+		TCP_SKB_CB(skb)->mptcp_flags = MPTCPHDR_SEQ;
+}
+
+static inline u8 mptcp_get_64_bit(u64 data_seq, struct mptcp_cb *mpcb)
+{
+	u64 data_seq_high = (u32)(data_seq >> 32);
+
+	if (mpcb->rcv_high_order[0] == data_seq_high)
+		return 0;
+	else if (mpcb->rcv_high_order[1] == data_seq_high)
+		return MPTCPHDR_SEQ64_INDEX;
+	else
+		return MPTCPHDR_SEQ64_OFO;
+}
+
+/* Sets the data_seq and returns pointer to the in-skb field of the data_seq.
+ * If the packet has a 64-bit dseq, the pointer points to the last 32 bits.
+ */
+static inline __u32 *mptcp_skb_set_data_seq(const struct sk_buff *skb,
+					    u32 *data_seq,
+					    struct mptcp_cb *mpcb)
+{
+	__u32 *ptr = (__u32 *)(skb_transport_header(skb) + TCP_SKB_CB(skb)->dss_off);
+
+	if (TCP_SKB_CB(skb)->mptcp_flags & MPTCPHDR_SEQ64_SET) {
+		u64 data_seq64 = get_unaligned_be64(ptr);
+
+		if (mpcb)
+			TCP_SKB_CB(skb)->mptcp_flags |= mptcp_get_64_bit(data_seq64, mpcb);
+
+		*data_seq = (u32)data_seq64 ;
+		ptr++;
+	} else {
+		*data_seq = get_unaligned_be32(ptr);
+	}
+
+	return ptr;
+}
+
+static inline struct sock *mptcp_meta_sk(const struct sock *sk)
+{
+	return tcp_sk(sk)->meta_sk;
+}
+
+static inline struct tcp_sock *mptcp_meta_tp(const struct tcp_sock *tp)
+{
+	return tcp_sk(tp->meta_sk);
+}
+
+static inline int is_meta_tp(const struct tcp_sock *tp)
+{
+	return tp->mpcb && mptcp_meta_tp(tp) == tp;
+}
+
+static inline int is_meta_sk(const struct sock *sk)
+{
+	return sk->sk_type == SOCK_STREAM  && sk->sk_protocol == IPPROTO_TCP &&
+	       tcp_sk(sk)->mpc && mptcp_meta_sk(sk) == sk;
+}
+
+static inline int is_master_tp(const struct tcp_sock *tp)
+{
+	return !tp->mpc || (!tp->mptcp->slave_sk && !is_meta_tp(tp));
+}
+
+static inline void mptcp_hash_request_remove(struct request_sock *req)
+{
+	int in_softirq = 0;
+
+	if (list_empty(&mptcp_rsk(req)->collide_tuple))
+		return;
+
+	if (in_softirq()) {
+		spin_lock(&mptcp_reqsk_hlock);
+		in_softirq = 1;
+	} else {
+		spin_lock_bh(&mptcp_reqsk_hlock);
+	}
+
+	list_del(&mptcp_rsk(req)->collide_tuple);
+
+	if (in_softirq)
+		spin_unlock(&mptcp_reqsk_hlock);
+	else
+		spin_unlock_bh(&mptcp_reqsk_hlock);
+}
+
+static inline void mptcp_reqsk_destructor(struct request_sock *req)
+{
+	if (!mptcp_rsk(req)->mpcb) {
+		if (hlist_nulls_unhashed(&mptcp_rsk(req)->collide_tk))
+			return;
+
+		if (in_softirq()) {
+			mptcp_reqsk_remove_tk(req);
+		} else {
+			rcu_read_lock_bh();
+			spin_lock(&mptcp_tk_hashlock);
+			hlist_nulls_del_rcu(&mptcp_rsk(req)->collide_tk);
+			spin_unlock(&mptcp_tk_hashlock);
+			rcu_read_unlock_bh();
+		}
+	} else {
+		mptcp_hash_request_remove(req);
+	}
+}
+
+static inline void mptcp_init_mp_opt(struct mptcp_options_received *mopt)
+{
+	mopt->saw_mpc = 0;
+	mopt->dss_csum = 0;
+	mopt->drop_me = 0;
+
+	mopt->is_mp_join = 0;
+	mopt->join_ack = 0;
+
+	mopt->saw_low_prio = 0;
+	mopt->low_prio = 0;
+
+	mopt->saw_add_addr = 0;
+	mopt->more_add_addr = 0;
+
+	mopt->saw_rem_addr = 0;
+	mopt->more_rem_addr = 0;
+
+	mopt->mp_fail = 0;
+	mopt->mp_fclose = 0;
+}
+
+static inline void mptcp_reset_mopt(struct tcp_sock *tp)
+{
+	struct mptcp_options_received *mopt = &tp->mptcp->rx_opt;
+
+	mopt->saw_low_prio = 0;
+	mopt->saw_add_addr = 0;
+	mopt->more_add_addr = 0;
+	mopt->saw_rem_addr = 0;
+	mopt->more_rem_addr = 0;
+	mopt->join_ack = 0;
+	mopt->mp_fail = 0;
+	mopt->mp_fclose = 0;
+}
+
+static inline __be32 mptcp_get_highorder_sndbits(const struct sk_buff *skb,
+						 const struct mptcp_cb *mpcb)
+{
+	return htonl(mpcb->snd_high_order[(TCP_SKB_CB(skb)->mptcp_flags &
+			MPTCPHDR_SEQ64_INDEX) ? 1 : 0]);
+}
+
+static inline u64 mptcp_get_data_seq_64(const struct mptcp_cb *mpcb, int index,
+					u32 data_seq_32)
+{
+	return ((u64)mpcb->rcv_high_order[index] << 32) | data_seq_32;
+}
+
+static inline u64 mptcp_get_rcv_nxt_64(const struct tcp_sock *meta_tp)
+{
+	struct mptcp_cb *mpcb = meta_tp->mpcb;
+	return mptcp_get_data_seq_64(mpcb, mpcb->rcv_hiseq_index,
+				     meta_tp->rcv_nxt);
+}
+
+static inline void mptcp_check_sndseq_wrap(struct tcp_sock *meta_tp, int inc)
+{
+	if (unlikely(meta_tp->snd_nxt > meta_tp->snd_nxt + inc)) {
+		struct mptcp_cb *mpcb = meta_tp->mpcb;
+		mpcb->snd_hiseq_index = mpcb->snd_hiseq_index ? 0 : 1;
+		mpcb->snd_high_order[mpcb->snd_hiseq_index] += 2;
+	}
+}
+
+static inline void mptcp_check_rcvseq_wrap(struct tcp_sock *meta_tp,
+					   u32 old_rcv_nxt)
+{
+	if (unlikely(old_rcv_nxt > meta_tp->rcv_nxt)) {
+		struct mptcp_cb *mpcb = meta_tp->mpcb;
+		mpcb->rcv_high_order[mpcb->rcv_hiseq_index] += 2;
+		mpcb->rcv_hiseq_index = mpcb->rcv_hiseq_index ? 0 : 1;
+	}
+}
+
+static inline int mptcp_sk_can_send(const struct sock *sk)
+{
+	return (1 << sk->sk_state) & (TCPF_ESTABLISHED | TCPF_CLOSE_WAIT);
+}
+
+static inline int mptcp_sk_can_recv(const struct sock *sk)
+{
+	return (1 << sk->sk_state) & (TCPF_ESTABLISHED | TCP_FIN_WAIT1 | TCP_FIN_WAIT2);
+}
+
+static inline int mptcp_sk_can_send_ack(const struct sock *sk)
+{
+	return !((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV |
+					TCPF_CLOSE | TCPF_LISTEN));
+}
+
+/* Only support GSO if all subflows supports it */
+static inline bool mptcp_sk_can_gso(const struct sock *meta_sk)
+{
+	struct sock *sk;
+
+	if (tcp_sk(meta_sk)->mpcb->dss_csum)
+		return 0;
+
+	mptcp_for_each_sk(tcp_sk(meta_sk)->mpcb, sk)
+		if (!sk_can_gso(sk))
+			return false;
+	return true;
+}
+
+static inline bool mptcp_can_sg(const struct sock *meta_sk)
+{
+	struct sock *sk;
+
+	if (tcp_sk(meta_sk)->mpcb->dss_csum)
+		return 0;
+
+	mptcp_for_each_sk(tcp_sk(meta_sk)->mpcb, sk)
+		if (!(sk->sk_route_caps & NETIF_F_SG))
+			return false;
+	return true;
+}
+
+/* Adding a new subflow to the rcv-buffer space. We make a simple addition,
+ * to give some space to allow traffic on the new subflow. Autotuning will
+ * increase it further later on.
+ */
+static inline void mptcp_init_buffer_space(struct sock *sk)
+{
+	struct sock *meta_sk = mptcp_meta_sk(sk);
+	int space = min(meta_sk->sk_rcvbuf + sk->sk_rcvbuf, sysctl_tcp_rmem[2]);
+
+	if (space > meta_sk->sk_rcvbuf) {
+		tcp_sk(meta_sk)->window_clamp += tcp_sk(sk)->window_clamp;
+		tcp_sk(meta_sk)->rcv_ssthresh += tcp_sk(sk)->rcv_ssthresh;
+		meta_sk->sk_rcvbuf = space;
+	}
+}
+
+static inline void mptcp_set_rto(struct sock *sk)
+{
+	struct tcp_sock *tp = tcp_sk(sk);
+	struct sock *sk_it;
+	struct inet_connection_sock *micsk = inet_csk(mptcp_meta_sk(sk));
+	__u32 max_rto = 0;
+
+	if (!tp->mpc)
+		return;
+
+	/* We are in recovery-phase on the MPTCP-level. Do not update the
+	 * RTO, because this would kill exponential backoff.
+	 */
+	if (micsk->icsk_retransmits)
+		return;
+
+	mptcp_for_each_sk(tp->mpcb, sk_it) {
+		if (mptcp_sk_can_send(sk_it) &&
+		    inet_csk(sk_it)->icsk_rto > max_rto)
+			max_rto = inet_csk(sk_it)->icsk_rto;
+	}
+	if (max_rto) {
+		micsk->icsk_rto = max_rto << 1;
+
+		/* A successfull rto-measurement - reset backoff counter */
+		micsk->icsk_backoff = 0;
+	}
+}
+
+static inline int mptcp_sysctl_syn_retries(void)
+{
+	return sysctl_mptcp_syn_retries;
+}
+
+static inline void mptcp_sub_close_passive(struct sock *sk)
+{
+	struct sock *meta_sk = mptcp_meta_sk(sk);
+	struct tcp_sock *tp = tcp_sk(sk), *meta_tp = tcp_sk(meta_sk);
+
+	/* Only close, if the app did a send-shutdown (passive close), and we
+	 * received the data-ack of the data-fin.
+	 */
+	if (tp->mpcb->passive_close && meta_tp->snd_una == meta_tp->write_seq)
+		mptcp_sub_close(sk, 0);
+}
+
+static inline int mptcp_fallback_infinite(struct sock *sk, int flag)
+{
+	struct tcp_sock *tp = tcp_sk(sk);
+
+	/* If data has been acknowleged on the meta-level, fully_established
+	 * will have been set before and thus we will not fall back to infinite
+	 * mapping.
+	 */
+	if (likely(tp->mptcp->fully_established))
+		return 0;
+
+	if (!(flag & MPTCP_FLAG_DATA_ACKED))
+		return 0;
+
+	/* Don't fallback twice ;) */
+	if (tp->mpcb->infinite_mapping_snd)
+		return 0;
+
+	pr_err("%s %#x will fallback - pi %d, src %pI4 dst %pI4 from %pS\n",
+	       __func__, tp->mpcb->mptcp_loc_token, tp->mptcp->path_index,
+	       &inet_sk(sk)->inet_saddr, &inet_sk(sk)->inet_daddr,
+	       __builtin_return_address(0));
+	if (!is_master_tp(tp))
+		return MPTCP_FLAG_SEND_RESET;
+
+	tp->mpcb->infinite_mapping_snd = 1;
+	tp->mpcb->infinite_mapping_rcv = 1;
+	tp->mptcp->fully_established = 1;
+
+	return 0;
+}
+
+/* Find the first free index in the bitfield */
+static inline int __mptcp_find_free_index(u8 bitfield, int j, u8 base)
+{
+	int i;
+	mptcp_for_each_bit_unset(bitfield >> base, i) {
+		/* We wrapped at the bitfield - try from 0 on */
+		if (i + base >= sizeof(bitfield) * 8) {
+			mptcp_for_each_bit_unset(bitfield, i) {
+				if (i != j)
+					return i;
+			}
+			goto exit;
+		}
+		if (i + base != j)
+			return i + base;
+	}
+exit:
+	return -1;
+}
+
+static inline int mptcp_find_free_index(u8 bitfield)
+{
+	return __mptcp_find_free_index(bitfield, -1, 0);
+}
+
+/* Find the first index whose bit in the bit-field == 0 */
+static inline u8 mptcp_set_new_pathindex(struct mptcp_cb *mpcb)
+{
+	u8 base = mpcb->next_path_index;
+	int i;
+
+	/* Start at 1, because 0 is reserved for the meta-sk */
+	mptcp_for_each_bit_unset(mpcb->path_index_bits >> base, i) {
+		if (i + base < 1)
+			continue;
+		if (i + base >= sizeof(mpcb->path_index_bits) * 8)
+			break;
+		i += base;
+		mpcb->path_index_bits |= (1 << i);
+		mpcb->next_path_index = i + 1;
+		return i;
+	}
+	mptcp_for_each_bit_unset(mpcb->path_index_bits, i) {
+		if (i < 1)
+			continue;
+		mpcb->path_index_bits |= (1 << i);
+		mpcb->next_path_index = i + 1;
+		return i;
+	}
+
+	return 0;
+}
+
+static inline int mptcp_v6_is_v4_mapped(struct sock *sk)
+{
+	return sk->sk_family == AF_INET6 &&
+	       ipv6_addr_type(&inet6_sk(sk)->saddr) == IPV6_ADDR_MAPPED;
+}
+#else /* CONFIG_MPTCP */
+#define mptcp_debug(fmt, args...)	\
+	do {				\
+	} while (0)
+
+/* Without MPTCP, we just do one iteration
+ * over the only socket available. This assumes that
+ * the sk/tp arg is the socket in that case.
+ */
+#define mptcp_for_each_sk(mpcb, sk)
+#define mptcp_for_each_sk_safe(__mpcb, __sk, __temp)
+
+static inline __u32 *mptcp_skb_set_data_seq(const struct sk_buff *skb,
+					    u32 *data_seq,
+					    struct mptcp_cb *mpcb)
+{
+	return 0;
+}
+static inline int mptcp_is_data_fin(const struct sk_buff *skb)
+{
+	return 0;
+}
+static inline int mptcp_is_data_seq(const struct sk_buff *skb)
+{
+	return 0;
+}
+static inline struct sock *mptcp_meta_sk(const struct sock *sk)
+{
+	return NULL;
+}
+static inline struct tcp_sock *mptcp_meta_tp(const struct tcp_sock *tp)
+{
+	return NULL;
+}
+static inline int is_meta_sk(const struct sock *sk)
+{
+	return 0;
+}
+static inline int is_master_tp(const struct tcp_sock *tp)
+{
+	return 0;
+}
+static inline void mptcp_purge_ofo_queue(struct tcp_sock *meta_tp) {}
+static inline void mptcp_cleanup_rbuf(const struct sock *meta_sk, int copied) {}
+static inline void mptcp_del_sock(const struct sock *sk) {}
+static inline void mptcp_reinject_data(struct sock *orig_sk, int clone_it) {}
+static inline void mptcp_init_buffer_space(const struct sock *sk) {}
+static inline void mptcp_update_sndbuf(const struct mptcp_cb *mpcb) {}
+static inline void mptcp_skb_entail_init(const struct tcp_sock *tp,
+					 const struct sk_buff *skb) {}
+static inline struct sk_buff *mptcp_next_segment(const struct sock *sk,
+						 const int *reinject)
+{
+	return NULL;
+}
+static inline void mptcp_clean_rtx_infinite(const struct sk_buff *skb,
+					    const struct sock *sk) {}
+static inline void mptcp_retransmit_timer(const struct sock *meta_sk) {}
+static inline int mptcp_write_wakeup(struct sock *meta_sk)
+{
+	return 0;
+}
+static inline void mptcp_sub_close(struct sock *sk, unsigned long delay) {}
+static inline void mptcp_set_rto(const struct sock *sk) {}
+static inline void mptcp_send_fin(const struct sock *meta_sk) {}
+static inline void mptcp_parse_options(const uint8_t *ptr, const int opsize,
+				       const struct tcp_options_received *opt_rx,
+				       const struct mptcp_options_received *mopt,
+				       const struct sk_buff *skb) {}
+static inline void mptcp_syn_options(struct sock *sk,
+				     struct tcp_out_options *opts,
+				     unsigned *remaining) {}
+static inline void mptcp_synack_options(struct request_sock *req,
+					struct tcp_out_options *opts,
+					unsigned *remaining) {}
+
+static inline void mptcp_established_options(struct sock *sk,
+					     struct sk_buff *skb,
+					     struct tcp_out_options *opts,
+					     unsigned *size) {}
+static inline void mptcp_options_write(__be32 *ptr, struct tcp_sock *tp,
+				       struct tcp_out_options *opts,
+				       struct sk_buff *skb) {}
+static inline void mptcp_close(struct sock *meta_sk, long timeout) {}
+static inline int mptcp_doit(struct sock *sk)
+{
+	return 0;
+}
+static inline int mptcp_check_req_master(const struct sock *sk,
+					 const struct sock *child,
+					 struct request_sock *req,
+					 struct request_sock **prev,
+					 const struct mptcp_options_received *mopt)
+{
+	return 1;
+}
+static inline struct sock *mptcp_check_req_child(struct sock *sk,
+						 struct sock *child,
+						 struct request_sock *req,
+						 struct request_sock **prev,
+						 struct mptcp_options_received *mopt)
+{
+	return NULL;
+}
+static inline u32 __mptcp_select_window(const struct sock *sk)
+{
+	return 0;
+}
+static inline void mptcp_select_initial_window(int *__space,
+					       __u32 *window_clamp,
+					       const struct sock *sk) {}
+static inline unsigned int mptcp_current_mss(struct sock *meta_sk)
+{
+	return 0;
+}
+static inline int mptcp_select_size(const struct sock *meta_sk, bool sg)
+{
+	return 0;
+}
+static inline void mptcp_key_sha1(u64 key, u32 *token, u64 *idsn) {}
+static inline void mptcp_sub_close_passive(struct sock *sk) {}
+static inline int mptcp_fallback_infinite(const struct sock *sk, int flag)
+{
+	return 0;
+}
+static inline void mptcp_init_mp_opt(const struct mptcp_options_received *mopt) {}
+static inline int mptcp_check_rtt(const struct tcp_sock *tp, int time)
+{
+	return 0;
+}
+static inline int mptcp_check_snd_buf(const struct tcp_sock *tp)
+{
+	return 0;
+}
+static inline int mptcp_sysctl_syn_retries(void)
+{
+	return 0;
+}
+static inline void mptcp_send_reset(const struct sock *sk) {}
+static inline void mptcp_send_active_reset(struct sock *meta_sk,
+					   gfp_t priority) {}
+static inline int mptcp_write_xmit(struct sock *sk, unsigned int mss_now,
+				   int nonagle, int push_one, gfp_t gfp)
+{
+	return 0;
+}
+static inline struct sock *mptcp_sk_clone(const struct sock *sk,
+					  int family, int priority)
+{
+	return NULL;
+}
+static inline void mptcp_set_keepalive(struct sock *sk, int val) {}
+static inline int mptcp_handle_options(struct sock *sk,
+				       const struct tcphdr *th,
+				       struct sk_buff *skb)
+{
+	return 0;
+}
+static inline void mptcp_reset_mopt(struct tcp_sock *tp) {}
+static inline void  __init mptcp_init(void) {}
+static inline int mptcp_trim_head(struct sock *sk, struct sk_buff *skb, u32 len)
+{
+	return 0;
+}
+static inline int mptcp_fragment(struct sock *sk, struct sk_buff *skb, u32 len,
+				 unsigned int mss_now, int reinject)
+{
+	return 0;
+}
+static inline int mptso_fragment(struct sock *sk, struct sk_buff *skb,
+				 unsigned int len, unsigned int mss_now,
+				 gfp_t gfp, int reinject)
+{
+	return 0;
+}
+static inline bool mptcp_sk_can_gso(const struct sock *sk)
+{
+	return false;
+}
+static inline bool mptcp_can_sg(const struct sock *meta_sk)
+{
+	return false;
+}
+static inline unsigned int mptcp_xmit_size_goal(struct sock *meta_sk,
+						u32 mss_now, int large_allowed)
+{
+	return 0;
+}
+static inline void mptcp_destroy_sock(struct sock *sk) {}
+static inline int mptcp_rcv_synsent_state_process(struct sock *sk,
+						  struct sock **skptr,
+						  struct sk_buff *skb,
+						  struct mptcp_options_received *mopt)
+{
+	return 0;
+}
+static inline bool mptcp_can_sendpage(struct sock *sk)
+{
+	return false;
+}
+static inline int mptcp_time_wait(struct sock *sk, struct tcp_timewait_sock *tw)
+{
+	return 0;
+}
+static inline void mptcp_twsk_destructor(struct tcp_timewait_sock *tw) {}
+static inline void mptcp_update_tw_socks(const struct tcp_sock *tp, int state) {}
+#endif /* CONFIG_MPTCP */
+
+#endif /* _MPTCP_H */
diff -Naur a/include/net/mptcp_pm.h b/include/net/mptcp_pm.h
--- a/include/net/mptcp_pm.h	1970-01-01 01:00:00.000000000 +0100
+++ b/include/net/mptcp_pm.h	2013-10-06 18:26:04.071871490 +0200
@@ -0,0 +1,133 @@
+/*
+ *	MPTCP implementation
+ *
+ *	Initial Design & Implementation:
+ *	Sébastien Barré <[e-mail]>
+ *
+ *	Current Maintainer & Author:
+ *	Christoph Paasch <[e-mail]>
+ *
+ *	Additional authors:
+ *	Jaakko Korkeaniemi <[e-mail]>
+ *	Gregory Detal <[e-mail]>
+ *	Fabien Duchêne <[e-mail]>
+ *	Andreas Seelinger <[e-mail]>
+ *	Lavkesh Lahngir <[e-mail]>
+ *	Andreas Ripke <[e-mail]>
+ *	Vlad Dogaru <[e-mail]>
+ *	Octavian Purdila <[e-mail]>
+ *	John Ronan <[e-mail]>
+ *	Catalin Nicutar <[e-mail]>
+ *	Brandon Heller <[e-mail]>
+ *
+ *
+ *	This program is free software; you can redistribute it and/or
+ *      modify it under the terms of the GNU General Public License
+ *      as published by the Free Software Foundation; either version
+ *      2 of the License, or (at your option) any later version.
+ */
+
+#ifndef _MPTCP_PM_H
+#define _MPTCP_PM_H
+
+#include <linux/in.h>
+#include <linux/in6.h>
+#include <linux/jhash.h>
+#include <linux/list.h>
+#include <linux/skbuff.h>
+#include <linux/spinlock_types.h>
+#include <linux/types.h>
+
+#include <net/request_sock.h>
+#include <net/sock.h>
+#include <net/tcp.h>
+
+/* Max number of local or remote addresses we can store.
+ * When changing, see the bitfield below in mptcp_loc4/6. */
+#define MPTCP_MAX_ADDR	8
+
+#define MPTCP_SUBFLOW_RETRY_DELAY	1000
+
+struct mptcp_loc4 {
+	u8		id;
+	u8		low_prio:1;
+	__be16		port;
+	struct in_addr	addr;
+};
+
+struct mptcp_rem4 {
+	u8		id;
+	u8		bitfield;
+	u8		retry_bitfield;
+	__be16		port;
+	struct in_addr	addr;
+};
+
+struct mptcp_loc6 {
+	u8		id;
+	u8		low_prio:1;
+	__be16		port;
+	struct in6_addr	addr;
+};
+
+struct mptcp_rem6 {
+	u8		id;
+	u8		bitfield;
+	u8		retry_bitfield;
+	__be16		port;
+	struct in6_addr	addr;
+};
+
+struct mptcp_cb;
+#ifdef CONFIG_MPTCP
+
+#define MPTCP_HASH_SIZE                1024
+
+/* This second hashtable is needed to retrieve request socks
+ * created as a result of a join request. While the SYN contains
+ * the token, the final ack does not, so we need a separate hashtable
+ * to retrieve the mpcb.
+ */
+extern struct list_head mptcp_reqsk_htb[MPTCP_HASH_SIZE];
+extern spinlock_t mptcp_reqsk_hlock;	/* hashtable protection */
+
+/* Lock, protecting the two hash-tables that hold the token. Namely,
+ * mptcp_reqsk_tk_htb and tk_hashtable
+ */
+extern spinlock_t mptcp_tk_hashlock;	/* hashtable protection */
+
+void mptcp_create_subflows(struct sock *meta_sk);
+void mptcp_create_subflow_worker(struct work_struct *work);
+void mptcp_retry_subflow_worker(struct work_struct *work);
+struct mp_join *mptcp_find_join(struct sk_buff *skb);
+u8 mptcp_get_loc_addrid(struct mptcp_cb *mpcb, struct sock *sk);
+void __mptcp_hash_insert(struct tcp_sock *meta_tp, u32 token);
+void mptcp_hash_remove_bh(struct tcp_sock *meta_tp);
+void mptcp_hash_remove(struct tcp_sock *meta_tp);
+struct sock *mptcp_hash_find(struct net *net, u32 token);
+int mptcp_lookup_join(struct sk_buff *skb, struct inet_timewait_sock *tw);
+int mptcp_do_join_short(struct sk_buff *skb, struct mptcp_options_received *mopt,
+			struct tcp_options_received *tmp_opt, struct net *net);
+void mptcp_reqsk_remove_tk(struct request_sock *reqsk);
+void mptcp_reqsk_new_mptcp(struct request_sock *req,
+			   const struct tcp_options_received *rx_opt,
+			   const struct mptcp_options_received *mopt,
+			   const struct sk_buff *skb);
+void mptcp_connect_init(struct sock *sk);
+void mptcp_set_addresses(struct sock *meta_sk);
+int mptcp_check_req(struct sk_buff *skb, struct net *net);
+void mptcp_address_worker(struct work_struct *work);
+int mptcp_pm_addr_event_handler(unsigned long event, void *ptr, int family);
+int mptcp_pm_init(void);
+void mptcp_pm_undo(void);
+
+#else /* CONFIG_MPTCP */
+static inline void mptcp_reqsk_new_mptcp(struct request_sock *req,
+					 const struct tcp_options_received *rx_opt,
+					 const struct mptcp_options_received *mopt,
+					 const struct sk_buff *skb)
+{}
+static inline void mptcp_hash_remove(struct tcp_sock *meta_tp) {}
+#endif /* CONFIG_MPTCP */
+
+#endif /*_MPTCP_PM_H*/
diff -Naur a/include/net/mptcp_v4.h b/include/net/mptcp_v4.h
--- a/include/net/mptcp_v4.h	1970-01-01 01:00:00.000000000 +0100
+++ b/include/net/mptcp_v4.h	2013-10-06 18:26:04.072871478 +0200
@@ -0,0 +1,81 @@
+/*
+ *	MPTCP implementation
+ *
+ *	Initial Design & Implementation:
+ *	Sébastien Barré <[e-mail]>
+ *
+ *	Current Maintainer & Author:
+ *	Christoph Paasch <[e-mail]>
+ *
+ *	Additional authors:
+ *	Jaakko Korkeaniemi <[e-mail]>
+ *	Gregory Detal <[e-mail]>
+ *	Fabien Duchêne <[e-mail]>
+ *	Andreas Seelinger <[e-mail]>
+ *	Lavkesh Lahngir <[e-mail]>
+ *	Andreas Ripke <[e-mail]>
+ *	Vlad Dogaru <[e-mail]>
+ *	Octavian Purdila <[e-mail]>
+ *	John Ronan <[e-mail]>
+ *	Catalin Nicutar <[e-mail]>
+ *	Brandon Heller <[e-mail]>
+ *
+ *
+ *	This program is free software; you can redistribute it and/or
+ *      modify it under the terms of the GNU General Public License
+ *      as published by the Free Software Foundation; either version
+ *      2 of the License, or (at your option) any later version.
+ */
+
+#ifndef MPTCP_V4_H_
+#define MPTCP_V4_H_
+
+
+#include <linux/in.h>
+#include <linux/skbuff.h>
+#include <net/mptcp.h>
+#include <net/mptcp_pm.h>
+#include <net/request_sock.h>
+#include <net/sock.h>
+
+extern struct request_sock_ops mptcp_request_sock_ops;
+extern struct proto mptcp_prot;
+
+#ifdef CONFIG_MPTCP
+
+int mptcp_v4_do_rcv(struct sock *meta_sk, struct sk_buff *skb);
+int mptcp_v4_rem_raddress(struct mptcp_cb *mpcb, u8 id);
+int mptcp_v4_add_raddress(struct mptcp_cb *mpcb, const struct in_addr *addr,
+			  __be16 port, u8 id);
+void mptcp_v4_set_init_addr_bit(struct mptcp_cb *mpcb, __be32 daddr);
+struct sock *mptcp_v4_search_req(const __be16 rport, const __be32 raddr,
+				 const __be32 laddr, const struct net *net);
+int mptcp_init4_subsockets(struct sock *meta_sk, const struct mptcp_loc4 *loc,
+			   struct mptcp_rem4 *rem);
+void mptcp_pm_addr4_event_handler(struct in_ifaddr *ifa, unsigned long event,
+				  struct mptcp_cb *mpcb);
+int mptcp_pm_v4_init(void);
+void mptcp_pm_v4_undo(void);
+void mptcp_v4_send_add_addr(int loc_id, struct mptcp_cb *mpcb);
+u32 mptcp_v4_get_nonce(__be32 saddr, __be32 daddr, __be16 sport, __be16 dport,
+		       u32 seq);
+u64 mptcp_v4_get_key(__be32 saddr, __be32 daddr, __be16 sport, __be16 dport);
+
+#else
+
+static inline int mptcp_v4_do_rcv(const struct sock *meta_sk,
+				  const struct sk_buff *skb)
+{
+	return 0;
+}
+
+static inline int mptcp_v4_send_synack(const struct sock *meta_sk,
+				       const struct request_sock *req,
+				       const struct request_values *rvp)
+{
+	return 0;
+}
+
+#endif /* CONFIG_MPTCP */
+
+#endif /* MPTCP_V4_H_ */
diff -Naur a/include/net/mptcp_v6.h b/include/net/mptcp_v6.h
--- a/include/net/mptcp_v6.h	1970-01-01 01:00:00.000000000 +0100
+++ b/include/net/mptcp_v6.h	2013-10-06 18:26:04.072871478 +0200
@@ -0,0 +1,87 @@
+/*
+ *	MPTCP implementation
+ *
+ *	Initial Design & Implementation:
+ *	Sébastien Barré <[e-mail]>
+ *
+ *	Current Maintainer & Author:
+ *	Jaakko Korkeaniemi <[e-mail]>
+ *
+ *	Additional authors:
+ *	Jaakko Korkeaniemi <[e-mail]>
+ *	Gregory Detal <[e-mail]>
+ *	Fabien Duchêne <[e-mail]>
+ *	Andreas Seelinger <[e-mail]>
+ *	Lavkesh Lahngir <[e-mail]>
+ *	Andreas Ripke <[e-mail]>
+ *	Vlad Dogaru <[e-mail]>
+ *	Octavian Purdila <[e-mail]>
+ *	John Ronan <[e-mail]>
+ *	Catalin Nicutar <[e-mail]>
+ *	Brandon Heller <[e-mail]>
+ *
+ *
+ *	This program is free software; you can redistribute it and/or
+ *      modify it under the terms of the GNU General Public License
+ *      as published by the Free Software Foundation; either version
+ *      2 of the License, or (at your option) any later version.
+ */
+
+#ifndef _MPTCP_V6_H
+#define _MPTCP_V6_H
+
+#include <linux/in6.h>
+#include <net/if_inet6.h>
+
+#include <net/mptcp.h>
+#include <net/mptcp_pm.h>
+
+extern struct request_sock_ops mptcp6_request_sock_ops;
+extern struct proto mptcpv6_prot;
+
+struct mptcp6_request_sock {
+	struct mptcp_request_sock	mptcp6rsk_tcp;
+	struct inet6_request_sock	mptcp6rsk_inet6;
+};
+
+#ifdef CONFIG_MPTCP
+
+/*
+ * Used to wait for DAD to finish. If rtr_solicit_delay is set, we use it
+ * instead
+ */
+#define MPTCP_IPV6_DEFAULT_DAD_WAIT (HZ/10)
+
+int mptcp_v6_do_rcv(struct sock *meta_sk, struct sk_buff *skb);
+int mptcp_v6_rem_raddress(struct mptcp_cb *mpcb, u8 id);
+int mptcp_v6_add_raddress(struct mptcp_cb *mpcb, const struct in6_addr *addr,
+			  __be16 port, u8 id);
+void mptcp_v6_set_init_addr_bit(struct mptcp_cb *mpcb,
+				const struct in6_addr *daddr);
+struct sock *mptcp_v6_search_req(const __be16 rport, const struct in6_addr *raddr,
+				 const struct in6_addr *laddr, const struct net *net);
+int mptcp_init6_subsockets(struct sock *meta_sk, const struct mptcp_loc6 *loc,
+			   struct mptcp_rem6 *rem);
+void mptcp_pm_addr6_event_handler(struct inet6_ifaddr *ifa, unsigned long event,
+				  struct mptcp_cb *mpcb);
+int mptcp_pm_v6_init(void);
+void mptcp_pm_v6_undo(void);
+void mptcp_v6_send_add_addr(int loc_id, struct mptcp_cb *mpcb);
+struct sock *mptcp_v6v4_syn_recv_sock(struct sock *sk, struct sk_buff *skb,
+				      struct request_sock *req,
+				      struct dst_entry *dst);
+__u32 mptcp_v6_get_nonce(const __be32 *saddr, const __be32 *daddr,
+			 __be16 sport, __be16 dport, u32 seq);
+u64 mptcp_v6_get_key(const __be32 *saddr, const __be32 *daddr,
+		     __be16 sport, __be16 dport);
+
+#else /* CONFIG_MPTCP */
+
+static inline int mptcp_v6_do_rcv(struct sock *meta_sk, struct sk_buff *skb)
+{
+	return 0;
+}
+
+#endif /* CONFIG_MPTCP */
+
+#endif /* _MPTCP_V6_H */
diff -Naur a/include/net/request_sock.h b/include/net/request_sock.h
--- a/include/net/request_sock.h	2013-09-02 22:46:10.000000000 +0200
+++ b/include/net/request_sock.h	2013-10-06 18:26:04.103871088 +0200
@@ -163,7 +163,8 @@
 };
 
 extern int reqsk_queue_alloc(struct request_sock_queue *queue,
-			     unsigned int nr_table_entries);
+			     unsigned int nr_table_entries,
+			     gfp_t flags);
 
 extern void __reqsk_queue_destroy(struct request_sock_queue *queue);
 extern void reqsk_queue_destroy(struct request_sock_queue *queue);
diff -Naur a/include/net/sock.h b/include/net/sock.h
--- a/include/net/sock.h	2013-09-02 22:46:10.000000000 +0200
+++ b/include/net/sock.h	2013-10-06 18:26:04.130870749 +0200
@@ -866,6 +866,16 @@
 
 extern int sk_wait_data(struct sock *sk, long *timeo);
 
+/* START - needed for MPTCP */
+extern void sock_def_error_report(struct sock *sk);
+extern struct sock *sk_prot_alloc(struct proto *prot, gfp_t priority,
+				  int family);
+extern void sock_lock_init(struct sock *sk);
+
+extern struct lock_class_key af_callback_keys[AF_MAX];
+extern char *const af_family_clock_key_strings[AF_MAX+1];
+/* END - needed for MPTCP */
+
 struct request_sock_ops;
 struct timewait_sock_ops;
 struct inet_hashinfo;
diff -Naur a/include/net/tcp.h b/include/net/tcp.h
--- a/include/net/tcp.h	2013-09-02 22:46:10.000000000 +0200
+++ b/include/net/tcp.h	2013-10-06 18:26:04.172870221 +0200
@@ -176,6 +176,7 @@
 #define TCPOPT_SACK             5       /* SACK Block */
 #define TCPOPT_TIMESTAMP	8	/* Better RTT estimations/PAWS */
 #define TCPOPT_MD5SIG		19	/* MD5 Signature (RFC2385) */
+#define TCPOPT_MPTCP		30
 #define TCPOPT_EXP		254	/* Experimental */
 /* Magic number to be after the option value for sharing TCP
  * experimental options. See draft-ietf-tcpm-experimental-options-00.txt
@@ -238,6 +239,28 @@
  */
 #define	TFO_SERVER_ALWAYS	0x1000
 
+/* Flags from tcp_input.c for tcp_ack */
+#define FLAG_DATA               0x01 /* Incoming frame contained data.          */
+#define FLAG_WIN_UPDATE         0x02 /* Incoming ACK was a window update.       */
+#define FLAG_DATA_ACKED         0x04 /* This ACK acknowledged new data.         */
+#define FLAG_RETRANS_DATA_ACKED 0x08 /* "" "" some of which was retransmitted.  */
+#define FLAG_SYN_ACKED          0x10 /* This ACK acknowledged SYN.              */
+#define FLAG_DATA_SACKED        0x20 /* New SACK.                               */
+#define FLAG_ECE                0x40 /* ECE in this ACK                         */
+#define FLAG_SLOWPATH           0x100 /* Do not skip RFC checks for window update.*/
+#define FLAG_ORIG_SACK_ACKED    0x200 /* Never retransmitted data are (s)acked  */
+#define FLAG_SND_UNA_ADVANCED   0x400 /* Snd_una was changed (!= FLAG_DATA_ACKED) */
+#define FLAG_DSACKING_ACK       0x800 /* SACK blocks contained D-SACK info */
+#define FLAG_SACK_RENEGING      0x2000 /* snd_una advanced to a sacked seq */
+#define FLAG_UPDATE_TS_RECENT   0x4000 /* tcp_replace_ts_recent() */
+#define MPTCP_FLAG_SEND_RESET	0x8000
+#define MPTCP_FLAG_DATA_ACKED	0x10000
+
+#define FLAG_ACKED              (FLAG_DATA_ACKED|FLAG_SYN_ACKED)
+#define FLAG_NOT_DUP            (FLAG_DATA|FLAG_WIN_UPDATE|FLAG_ACKED)
+#define FLAG_CA_ALERT           (FLAG_DATA_SACKED|FLAG_ECE)
+#define FLAG_FORWARD_PROGRESS   (FLAG_ACKED|FLAG_DATA_SACKED)
+
 extern struct inet_timewait_death_row tcp_death_row;
 
 /* sysctl variables for tcp */
@@ -350,6 +373,105 @@
 #define TCP_ADD_STATS_USER(net, field, val) SNMP_ADD_STATS_USER((net)->mib.tcp_statistics, field, val)
 #define TCP_ADD_STATS(net, field, val)	SNMP_ADD_STATS((net)->mib.tcp_statistics, field, val)
 
+/**** START - Exports needed for MPTCP ****/
+extern const struct inet_connection_sock_af_ops ipv4_specific;
+extern const struct inet_connection_sock_af_ops ipv6_specific;
+extern const struct inet_connection_sock_af_ops ipv6_mapped;
+
+struct mptcp_options_received;
+
+extern int tcp_close_state(struct sock *sk);
+extern void tcp_push(struct sock *sk, int flags, int mss_now,
+			    int nonagle);
+extern int tcp_xmit_probe_skb(struct sock *sk, int urgent);
+extern void tcp_cwnd_validate(struct sock *sk);
+extern void tcp_event_new_data_sent(struct sock *sk, const struct sk_buff *skb);
+extern int tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, int clone_it,
+			    gfp_t gfp_mask);
+extern unsigned int tcp_mss_split_point(const struct sock *sk, const struct sk_buff *skb,
+					unsigned int mss_now, unsigned int cwnd);
+extern bool tcp_tso_should_defer(struct sock *sk, struct sk_buff *skb);
+extern bool tcp_nagle_test(const struct tcp_sock *tp, const struct sk_buff *skb,
+			   unsigned int cur_mss, int nonagle);
+extern bool tcp_snd_wnd_test(const struct tcp_sock *tp, const struct sk_buff *skb,
+			     unsigned int cur_mss);
+extern unsigned int tcp_cwnd_test(const struct tcp_sock *tp, const struct sk_buff *skb);
+extern int tcp_mtu_probe(struct sock *sk);
+extern int tcp_init_tso_segs(const struct sock *sk, struct sk_buff *skb,
+			     unsigned int mss_now);
+extern void __pskb_trim_head(struct sk_buff *skb, int len);
+extern void tcp_queue_skb(struct sock *sk, struct sk_buff *skb);
+extern void tcp_init_nondata_skb(struct sk_buff *skb, u32 seq, u8 flags);
+extern void tcp_reset(struct sock *sk);
+extern bool tcp_may_update_window(const struct tcp_sock *tp, const u32 ack,
+				  const u32 ack_seq, const u32 nwin);
+extern bool tcp_urg_mode(const struct tcp_sock *tp);
+extern void tcp_ack_probe(struct sock *sk);
+extern void tcp_rearm_rto(struct sock *sk);
+extern int tcp_write_timeout(struct sock *sk);
+extern bool retransmits_timed_out(struct sock *sk, unsigned int boundary,
+				  unsigned int timeout, bool syn_set);
+extern void tcp_write_err(struct sock *sk);
+extern void tcp_adjust_pcount(struct sock *sk, const struct sk_buff *skb, int decr);
+extern void tcp_set_skb_tso_segs(const struct sock *sk, struct sk_buff *skb,
+				 unsigned int mss_now);
+
+extern int tcp_v4_rtx_synack(struct sock *sk, struct request_sock *req);
+extern void tcp_v4_reqsk_send_ack(struct sock *sk, struct sk_buff *skb,
+				  struct request_sock *req);
+extern __u32 tcp_v4_init_sequence(const struct sk_buff *skb);
+extern int tcp_v4_send_synack(struct sock *sk, struct dst_entry *dst,
+			      struct request_sock *req, u16 queue_mapping,
+			      bool nocache);
+extern void tcp_v4_send_reset(struct sock *sk, struct sk_buff *skb);
+extern struct ip_options_rcu *tcp_v4_save_options(struct sk_buff *skb);
+extern struct sock *tcp_v4_hnd_req(struct sock *sk, struct sk_buff *skb);
+extern void tcp_v4_reqsk_destructor(struct request_sock *req);
+
+extern int tcp_v6_rtx_synack(struct sock *sk, struct request_sock *req);
+extern void tcp_v6_reqsk_send_ack(struct sock *sk, struct sk_buff *skb,
+				  struct request_sock *req);
+extern __u32 tcp_v6_init_sequence(const struct sk_buff *skb);
+extern int tcp_v6_send_synack(struct sock *sk, struct dst_entry *dst,
+			      struct flowi6 *fl6, struct request_sock *req,
+			      u16 queue_mapping);
+extern void tcp_v6_send_reset(struct sock *sk, struct sk_buff *skb);
+extern int tcp_v6_do_rcv(struct sock *sk, struct sk_buff *skb);
+extern int tcp_v6_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len);
+extern void tcp_v6_destroy_sock(struct sock *sk);
+void inet6_sk_rx_dst_set(struct sock *sk, const struct sk_buff *skb);
+extern void tcp_v6_hash(struct sock *sk);
+extern struct sock *tcp_v6_hnd_req(struct sock *sk,struct sk_buff *skb);
+extern struct sock *tcp_v6_syn_recv_sock(struct sock *sk, struct sk_buff *skb,
+					 struct request_sock *req,
+					 struct dst_entry *dst);
+extern void tcp_v6_reqsk_destructor(struct request_sock *req);
+
+extern void sock_valbool_flag(struct sock *sk, int bit, int valbool);
+extern unsigned int tcp_xmit_size_goal(struct sock *sk, u32 mss_now,
+				       int large_allowed);
+extern u32 tcp_tso_acked(struct sock *sk, struct sk_buff *skb);
+
+extern void skb_clone_fraglist(struct sk_buff *skb);
+extern void copy_skb_header(struct sk_buff *new, const struct sk_buff *old);
+
+extern void inet_twsk_free(struct inet_timewait_sock *tw);
+/* These states need RST on ABORT according to RFC793 */
+static inline bool tcp_need_reset(int state)
+{
+	return (1 << state) &
+	       (TCPF_ESTABLISHED | TCPF_CLOSE_WAIT | TCPF_FIN_WAIT1 |
+		TCPF_FIN_WAIT2 | TCPF_SYN_RECV);
+}
+
+extern bool tcp_dma_try_early_copy(struct sock *sk, struct sk_buff *skb,
+				   int hlen);
+extern int __must_check tcp_queue_rcv(struct sock *sk, struct sk_buff *skb, int hdrlen,
+				      bool *fragstolen);
+extern bool tcp_try_coalesce(struct sock *sk, struct sk_buff *to,
+			     struct sk_buff *from, bool *fragstolen);
+/**** END - Exports needed for MPTCP ****/
+
 extern void tcp_init_mem(struct net *net);
 
 extern void tcp_tasklet_init(void);
@@ -448,6 +570,7 @@
 		       size_t len, int nonblock, int flags, int *addr_len);
 extern void tcp_parse_options(const struct sk_buff *skb,
 			      struct tcp_options_received *opt_rx,
+			      struct mptcp_options_received *mopt,
 			      int estab, struct tcp_fastopen_cookie *foc);
 extern const u8 *tcp_parse_md5sig_option(const struct tcphdr *th);
 
@@ -681,6 +804,21 @@
 #define TCPHDR_ECE 0x40
 #define TCPHDR_CWR 0x80
 
+/* MPTCP flags */
+#define MPTCPHDR_ACK		0x01
+#define MPTCPHDR_SEQ		0x02
+#define MPTCPHDR_FIN		0x04
+#define MPTCPHDR_INF		0x08
+#define MPTCPHDR_SEQ64_SET	0x10 /* Did we received a 64-bit seq number */
+#define MPTCPHDR_SEQ64_OFO	0x20 /* Is it not in our circular array? */
+#define MPTCPHDR_SEQ64_INDEX	0x40 /* Index of seq in mpcb->snd_high_order */
+#define MPTCPHDR_DSS_CSUM	0x80
+
+/* It is impossible, that all 8 bits of mptcp_flags are set to 1 with the above
+ * Thus, defining MPTCPHDR_JOIN as 0xFF is safe.
+ */
+#define MPTCPHDR_JOIN		0xFF
+
 /* This is what the send packet queuing engine uses to pass
  * TCP per-packet control information to the transmission code.
  * We also store the host-order sequence numbers in here too.
@@ -689,14 +827,24 @@
  */
 struct tcp_skb_cb {
 	union {
-		struct inet_skb_parm	h4;
+		union {
+			struct inet_skb_parm	h4;
 #if IS_ENABLED(CONFIG_IPV6)
-		struct inet6_skb_parm	h6;
+			struct inet6_skb_parm	h6;
+#endif
+		} header;	/* For incoming frames		*/
+#ifdef CONFIG_MPTCP
+		__u32 path_mask; /* path indices that tried to send this skb */
 #endif
-	} header;	/* For incoming frames		*/
+	};
 	__u32		seq;		/* Starting sequence number	*/
 	__u32		end_seq;	/* SEQ + FIN + SYN + datalen	*/
 	__u32		when;		/* used to compute rtt's	*/
+#ifdef CONFIG_MPTCP
+	__u8		mptcp_flags;	/* flags for the MPTCP layer    */
+	__u8		dss_off;	/* Number of 4-byte words until
+					 * seq-number */
+#endif
 	__u8		tcp_flags;	/* TCP header flags. (tcp[13])	*/
 
 	__u8		sacked;		/* State flags for SACK/FACK.	*/
@@ -1050,7 +1198,7 @@
 extern void tcp_select_initial_window(int __space, __u32 mss,
 				      __u32 *rcv_wnd, __u32 *window_clamp,
 				      int wscale_ok, __u8 *rcv_wscale,
-				      __u32 init_rcv_wnd);
+				      __u32 init_rcv_wnd, const struct sock *sk);
 
 static inline int tcp_win_from_space(int space)
 {
@@ -1062,12 +1210,18 @@
 /* Note: caller must be prepared to deal with negative returns */ 
 static inline int tcp_space(const struct sock *sk)
 {
+	if (tcp_sk(sk)->mpc)
+		sk = tcp_sk(sk)->meta_sk;
+
 	return tcp_win_from_space(sk->sk_rcvbuf -
 				  atomic_read(&sk->sk_rmem_alloc));
 } 
 
 static inline int tcp_full_space(const struct sock *sk)
 {
+	if (tcp_sk(sk)->mpc)
+		sk = tcp_sk(sk)->meta_sk;
+
 	return tcp_win_from_space(sk->sk_rcvbuf); 
 }
 
@@ -1082,6 +1236,7 @@
 	tcp_rsk(req)->rcv_isn = TCP_SKB_CB(skb)->seq;
 	tcp_rsk(req)->rcv_nxt = TCP_SKB_CB(skb)->seq + 1;
 	tcp_rsk(req)->snt_synack = 0;
+	tcp_rsk(req)->saw_mpc = 0;
 	req->mss = rx_opt->mss_clamp;
 	req->ts_recent = rx_opt->saw_tstamp ? rx_opt->rcv_tsval : 0;
 	ireq->tstamp_ok = rx_opt->tstamp_ok;
diff -Naur a/include/uapi/linux/if.h b/include/uapi/linux/if.h
--- a/include/uapi/linux/if.h	2013-09-02 22:46:10.000000000 +0200
+++ b/include/uapi/linux/if.h	2013-10-06 18:26:04.179870133 +0200
@@ -53,6 +53,9 @@
 
 #define IFF_ECHO	0x40000		/* echo sent packets		*/
 
+#define IFF_NOMULTIPATH	0x80000		/* Disable for MPTCP 		*/
+#define IFF_MPBACKUP	0x100000	/* Use as backup path for MPTCP */
+
 #define IFF_VOLATILE	(IFF_LOOPBACK|IFF_POINTOPOINT|IFF_BROADCAST|IFF_ECHO|\
 		IFF_MASTER|IFF_SLAVE|IFF_RUNNING|IFF_LOWER_UP|IFF_DORMANT)
 
diff -Naur a/net/core/dev.c b/net/core/dev.c
--- a/net/core/dev.c	2013-09-02 22:46:10.000000000 +0200
+++ b/net/core/dev.c	2013-10-06 18:26:04.194869944 +0200
@@ -4801,7 +4801,7 @@
 
 	dev->flags = (flags & (IFF_DEBUG | IFF_NOTRAILERS | IFF_NOARP |
 			       IFF_DYNAMIC | IFF_MULTICAST | IFF_PORTSEL |
-			       IFF_AUTOMEDIA)) |
+			       IFF_AUTOMEDIA | IFF_NOMULTIPATH | IFF_MPBACKUP)) |
 		     (dev->flags & (IFF_UP | IFF_VOLATILE | IFF_PROMISC |
 				    IFF_ALLMULTI));
 
diff -Naur a/net/core/request_sock.c b/net/core/request_sock.c
--- a/net/core/request_sock.c	2013-09-02 22:46:10.000000000 +0200
+++ b/net/core/request_sock.c	2013-10-06 18:26:04.196869919 +0200
@@ -38,7 +38,8 @@
 EXPORT_SYMBOL(sysctl_max_syn_backlog);
 
 int reqsk_queue_alloc(struct request_sock_queue *queue,
-		      unsigned int nr_table_entries)
+		      unsigned int nr_table_entries,
+		      gfp_t flags)
 {
 	size_t lopt_size = sizeof(struct listen_sock);
 	struct listen_sock *lopt;
@@ -48,9 +49,11 @@
 	nr_table_entries = roundup_pow_of_two(nr_table_entries + 1);
 	lopt_size += nr_table_entries * sizeof(struct request_sock *);
 	if (lopt_size > PAGE_SIZE)
-		lopt = vzalloc(lopt_size);
+		lopt = __vmalloc(lopt_size,
+			flags | __GFP_HIGHMEM | __GFP_ZERO,
+			PAGE_KERNEL);
 	else
-		lopt = kzalloc(lopt_size, GFP_KERNEL);
+		lopt = kzalloc(lopt_size, flags);
 	if (lopt == NULL)
 		return -ENOMEM;
 
diff -Naur a/net/core/skbuff.c b/net/core/skbuff.c
--- a/net/core/skbuff.c	2013-09-02 22:46:10.000000000 +0200
+++ b/net/core/skbuff.c	2013-10-06 18:26:04.207869781 +0200
@@ -487,7 +487,7 @@
 	skb_drop_list(&skb_shinfo(skb)->frag_list);
 }
 
-static void skb_clone_fraglist(struct sk_buff *skb)
+void skb_clone_fraglist(struct sk_buff *skb)
 {
 	struct sk_buff *list;
 
@@ -913,7 +913,7 @@
 	skb->inner_mac_header += off;
 }
 
-static void copy_skb_header(struct sk_buff *new, const struct sk_buff *old)
+void copy_skb_header(struct sk_buff *new, const struct sk_buff *old)
 {
 	__copy_skb_header(new, old);
 
diff -Naur a/net/core/sock.c b/net/core/sock.c
--- a/net/core/sock.c	2013-09-02 22:46:10.000000000 +0200
+++ b/net/core/sock.c	2013-10-06 18:26:04.239869378 +0200
@@ -230,7 +230,7 @@
   "slock-AF_IEEE802154", "slock-AF_CAIF" , "slock-AF_ALG"      ,
   "slock-AF_NFC"   , "slock-AF_VSOCK"    ,"slock-AF_MAX"
 };
-static const char *const af_family_clock_key_strings[AF_MAX+1] = {
+char *const af_family_clock_key_strings[AF_MAX+1] = {
   "clock-AF_UNSPEC", "clock-AF_UNIX"     , "clock-AF_INET"     ,
   "clock-AF_AX25"  , "clock-AF_IPX"      , "clock-AF_APPLETALK",
   "clock-AF_NETROM", "clock-AF_BRIDGE"   , "clock-AF_ATMPVC"   ,
@@ -251,7 +251,7 @@
  * sk_callback_lock locking rules are per-address-family,
  * so split the lock classes by using a per-AF key:
  */
-static struct lock_class_key af_callback_keys[AF_MAX];
+struct lock_class_key af_callback_keys[AF_MAX];
 
 /* Take into consideration the size of the struct sk_buff overhead in the
  * determination of these values, since that is non-constant across
@@ -607,7 +607,7 @@
 	return ret;
 }
 
-static inline void sock_valbool_flag(struct sock *sk, int bit, int valbool)
+void sock_valbool_flag(struct sock *sk, int bit, int valbool)
 {
 	if (valbool)
 		sock_set_flag(sk, bit);
@@ -1195,7 +1195,7 @@
  *
  * (We also register the sk_lock with the lock validator.)
  */
-static inline void sock_lock_init(struct sock *sk)
+void sock_lock_init(struct sock *sk)
 {
 	sock_lock_init_class_and_name(sk,
 			af_family_slock_key_strings[sk->sk_family],
@@ -1243,7 +1243,7 @@
 }
 EXPORT_SYMBOL(sk_prot_clear_portaddr_nulls);
 
-static struct sock *sk_prot_alloc(struct proto *prot, gfp_t priority,
+struct sock *sk_prot_alloc(struct proto *prot, gfp_t priority,
 		int family)
 {
 	struct sock *sk;
@@ -2163,7 +2163,7 @@
 	rcu_read_unlock();
 }
 
-static void sock_def_error_report(struct sock *sk)
+void sock_def_error_report(struct sock *sk)
 {
 	struct socket_wq *wq;
 
diff -Naur a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c
--- a/net/ipv4/af_inet.c	2013-09-02 22:46:10.000000000 +0200
+++ b/net/ipv4/af_inet.c	2013-10-06 18:26:04.252869215 +0200
@@ -104,6 +104,7 @@
 #include <net/ip_fib.h>
 #include <net/inet_connection_sock.h>
 #include <net/tcp.h>
+#include <net/mptcp.h>
 #include <net/udp.h>
 #include <net/udplite.h>
 #include <net/ping.h>
@@ -274,8 +275,7 @@
  *	Create an inet socket.
  */
 
-static int inet_create(struct net *net, struct socket *sock, int protocol,
-		       int kern)
+int inet_create(struct net *net, struct socket *sock, int protocol, int kern)
 {
 	struct sock *sk;
 	struct inet_protosw *answer;
@@ -711,6 +711,23 @@
 	lock_sock(sk2);
 
 	sock_rps_record_flow(sk2);
+
+	if (sk2->sk_protocol == IPPROTO_TCP && tcp_sk(sk2)->mpc) {
+		struct sock *sk_it;
+
+		mptcp_for_each_sk(tcp_sk(sk2)->mpcb, sk_it)
+				sock_rps_record_flow(sk_it);
+
+		if (tcp_sk(sk2)->mpcb->master_sk) {
+			sk_it = tcp_sk(sk2)->mpcb->master_sk;
+
+			write_lock_bh(&sk_it->sk_callback_lock);
+			sk_it->sk_wq = newsock->wq;
+			sk_it->sk_socket = newsock;
+			write_unlock_bh(&sk_it->sk_callback_lock);
+		}
+	}
+
 	WARN_ON(!((1 << sk2->sk_state) &
 		  (TCPF_ESTABLISHED | TCPF_SYN_RECV |
 		  TCPF_CLOSE_WAIT | TCPF_CLOSE)));
@@ -1755,6 +1772,9 @@
 
 	ip_init();
 
+	/* We must initialize MPTCP before TCP. */
+	mptcp_init();
+
 	tcp_v4_init();
 
 	/* Setup TCP slab cache for open requests. */
diff -Naur a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c
--- a/net/ipv4/inet_connection_sock.c	2013-09-02 22:46:10.000000000 +0200
+++ b/net/ipv4/inet_connection_sock.c	2013-10-06 18:26:04.263869077 +0200
@@ -23,6 +23,7 @@
 #include <net/route.h>
 #include <net/tcp_states.h>
 #include <net/xfrm.h>
+#include <net/mptcp.h>
 
 #ifdef INET_CSK_DEBUG
 const char inet_csk_timer_bug_msg[] = "inet_csk BUG: unknown timer value\n";
@@ -477,8 +478,8 @@
 }
 EXPORT_SYMBOL_GPL(inet_csk_route_child_sock);
 
-static inline u32 inet_synq_hash(const __be32 raddr, const __be16 rport,
-				 const u32 rnd, const u32 synq_hsize)
+u32 inet_synq_hash(const __be32 raddr, const __be16 rport, const u32 rnd,
+		   const u32 synq_hsize)
 {
 	return jhash_2words((__force u32)raddr, (__force u32)rport, rnd) & (synq_hsize - 1);
 }
@@ -675,7 +676,12 @@
 				 const struct request_sock *req,
 				 const gfp_t priority)
 {
-	struct sock *newsk = sk_clone_lock(sk, priority);
+	struct sock *newsk;
+
+	if (sk->sk_protocol == IPPROTO_TCP && tcp_sk(sk)->mpc)
+		newsk = mptcp_sk_clone(sk, req->rsk_ops->family, priority);
+	else
+		newsk = sk_clone_lock(sk, priority);
 
 	if (newsk != NULL) {
 		struct inet_connection_sock *newicsk = inet_csk(newsk);
@@ -752,7 +758,8 @@
 {
 	struct inet_sock *inet = inet_sk(sk);
 	struct inet_connection_sock *icsk = inet_csk(sk);
-	int rc = reqsk_queue_alloc(&icsk->icsk_accept_queue, nr_table_entries);
+	int rc = reqsk_queue_alloc(&icsk->icsk_accept_queue, nr_table_entries,
+			GFP_KERNEL);
 
 	if (rc != 0)
 		return rc;
@@ -813,6 +820,8 @@
 
 		acc_req = req->dl_next;
 
+		if (is_meta_sk(child))
+			mutex_lock(&tcp_sk(child)->mpcb->mutex);
 		local_bh_disable();
 		bh_lock_sock(child);
 		WARN_ON(sock_owned_by_user(child));
@@ -841,6 +850,8 @@
 
 		bh_unlock_sock(child);
 		local_bh_enable();
+		if (is_meta_sk(child))
+			mutex_unlock(&tcp_sk(child)->mpcb->mutex);
 		sock_put(child);
 
 		sk_acceptq_removed(sk);
diff -Naur a/net/ipv4/inet_timewait_sock.c b/net/ipv4/inet_timewait_sock.c
--- a/net/ipv4/inet_timewait_sock.c	2013-09-02 22:46:10.000000000 +0200
+++ b/net/ipv4/inet_timewait_sock.c	2013-10-06 18:26:04.278868888 +0200
@@ -99,7 +99,7 @@
 	}
 }
 
-static noinline void inet_twsk_free(struct inet_timewait_sock *tw)
+void inet_twsk_free(struct inet_timewait_sock *tw)
 {
 	struct module *owner = tw->tw_prot->owner;
 	twsk_destructor((struct sock *)tw);
diff -Naur a/net/ipv4/Kconfig b/net/ipv4/Kconfig
--- a/net/ipv4/Kconfig	2013-09-02 22:46:10.000000000 +0200
+++ b/net/ipv4/Kconfig	2013-10-06 18:26:04.279868875 +0200
@@ -572,6 +572,22 @@
 	For further details see:
 	  http://www.ews.uiuc.edu/~shaoliu/tcpillinois/index.html
 
+config TCP_CONG_COUPLED
+	tristate "MPTCP COUPLED CONGESTION CONTROL"
+	depends on MPTCP
+	default n
+	---help---
+	MultiPath TCP Coupled Congestion Control
+	To enable it, just put 'coupled' in tcp_congestion_control
+
+config TCP_CONG_OLIA
+	tristate "MPTCP Opportunistic Linked Increase"
+	depends on MPTCP
+	default n
+	---help---
+	MultiPath TCP Opportunistic Linked Increase Congestion Control
+	To enable it, just put 'olia' in tcp_congestion_control
+
 choice
 	prompt "Default TCP congestion control"
 	default DEFAULT_CUBIC
@@ -600,6 +616,12 @@
 	config DEFAULT_WESTWOOD
 		bool "Westwood" if TCP_CONG_WESTWOOD=y
 
+	config DEFAULT_COUPLED
+		bool "Coupled" if TCP_CONG_COUPLED=y
+
+	config DEFAULT_OLIA
+		bool "Olia" if TCP_CONG_OLIA=y
+
 	config DEFAULT_RENO
 		bool "Reno"
 
@@ -621,6 +643,7 @@
 	default "vegas" if DEFAULT_VEGAS
 	default "westwood" if DEFAULT_WESTWOOD
 	default "veno" if DEFAULT_VENO
+	default "coupled" if DEFAULT_COUPLED
 	default "reno" if DEFAULT_RENO
 	default "cubic"
 
diff -Naur a/net/ipv4/syncookies.c b/net/ipv4/syncookies.c
--- a/net/ipv4/syncookies.c	2013-09-02 22:46:10.000000000 +0200
+++ b/net/ipv4/syncookies.c	2013-10-06 18:26:04.321868347 +0200
@@ -293,7 +293,7 @@
 
 	/* check for timestamp cookie support */
 	memset(&tcp_opt, 0, sizeof(tcp_opt));
-	tcp_parse_options(skb, &tcp_opt, 0, NULL);
+	tcp_parse_options(skb, &tcp_opt, NULL, 0, NULL);
 
 	if (!cookie_check_timestamp(&tcp_opt, sock_net(sk), &ecn_ok))
 		goto out;
@@ -366,7 +366,7 @@
 	tcp_select_initial_window(tcp_full_space(sk), req->mss,
 				  &req->rcv_wnd, &req->window_clamp,
 				  ireq->wscale_ok, &rcv_wscale,
-				  dst_metric(&rt->dst, RTAX_INITRWND));
+				  dst_metric(&rt->dst, RTAX_INITRWND), sk);
 
 	ireq->rcv_wscale  = rcv_wscale;
 
diff -Naur a/net/ipv4/tcp.c b/net/ipv4/tcp.c
--- a/net/ipv4/tcp.c	2013-09-02 22:46:10.000000000 +0200
+++ b/net/ipv4/tcp.c	2013-10-06 18:26:04.323868322 +0200
@@ -271,6 +271,7 @@
 
 #include <net/icmp.h>
 #include <net/inet_common.h>
+#include <net/mptcp.h>
 #include <net/tcp.h>
 #include <net/xfrm.h>
 #include <net/ip.h>
@@ -605,6 +606,7 @@
 	tcb->seq     = tcb->end_seq = tp->write_seq;
 	tcb->tcp_flags = TCPHDR_ACK;
 	tcb->sacked  = 0;
+	mptcp_skb_entail_init(tp, skb);
 	skb_header_release(skb);
 	tcp_add_write_queue_tail(sk, skb);
 	sk->sk_wmem_queued += skb->truesize;
@@ -619,7 +621,7 @@
 		tp->snd_up = tp->write_seq;
 }
 
-static inline void tcp_push(struct sock *sk, int flags, int mss_now,
+void tcp_push(struct sock *sk, int flags, int mss_now,
 			    int nonagle)
 {
 	if (tcp_send_head(sk)) {
@@ -685,6 +687,14 @@
 	int ret;
 
 	sock_rps_record_flow(sk);
+
+#ifdef CONFIG_MPTCP
+	if (tcp_sk(sk)->mpc) {
+		struct sock *sk_it;
+		mptcp_for_each_sk(tcp_sk(sk)->mpcb, sk_it)
+				sock_rps_record_flow(sk_it);
+	}
+#endif
 	/*
 	 * We can't seek on a socket input
 	 */
@@ -780,8 +790,7 @@
 	return NULL;
 }
 
-static unsigned int tcp_xmit_size_goal(struct sock *sk, u32 mss_now,
-				       int large_allowed)
+unsigned int tcp_xmit_size_goal(struct sock *sk, u32 mss_now, int large_allowed)
 {
 	struct tcp_sock *tp = tcp_sk(sk);
 	u32 xmit_size_goal, old_size_goal;
@@ -821,8 +830,13 @@
 {
 	int mss_now;
 
-	mss_now = tcp_current_mss(sk);
-	*size_goal = tcp_xmit_size_goal(sk, mss_now, !(flags & MSG_OOB));
+	if (tcp_sk(sk)->mpc) {
+		mss_now = mptcp_current_mss(sk);
+		*size_goal = mptcp_xmit_size_goal(sk, mss_now, !(flags & MSG_OOB));
+	} else {
+		mss_now = tcp_current_mss(sk);
+		*size_goal = tcp_xmit_size_goal(sk, mss_now, !(flags & MSG_OOB));
+	}
 
 	return mss_now;
 }
@@ -846,6 +860,26 @@
 			goto out_err;
 	}
 
+	if (tp->mpc) {
+		struct sock *sk_it;
+
+		/* We must check this with socket-lock hold because we iterate
+		 * over the subflows.
+		 */
+		if (!mptcp_can_sendpage(sk)) {
+			ssize_t ret;
+
+			release_sock(sk);
+			ret = sock_no_sendpage(sk->sk_socket, page, offset,
+					       size, flags);
+			lock_sock(sk);
+			return ret;
+		}
+
+		mptcp_for_each_sk(tp->mpcb, sk_it)
+			sock_rps_record_flow(sk_it);
+	}
+
 	clear_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags);
 
 	mss_now = tcp_send_mss(sk, &size_goal, flags);
@@ -949,8 +983,9 @@
 {
 	ssize_t res;
 
-	if (!(sk->sk_route_caps & NETIF_F_SG) ||
-	    !(sk->sk_route_caps & NETIF_F_ALL_CSUM))
+	/* If MPTCP is enabled, we check it later after establishment */
+	if (!tcp_sk(sk)->mpc && (!(sk->sk_route_caps & NETIF_F_SG) ||
+	    !(sk->sk_route_caps & NETIF_F_ALL_CSUM)))
 		return sock_no_sendpage(sk->sk_socket, page, offset, size,
 					flags);
 
@@ -966,6 +1001,9 @@
 	const struct tcp_sock *tp = tcp_sk(sk);
 	int tmp = tp->mss_cache;
 
+	if (tp->mpc)
+		return mptcp_select_size(sk, sg);
+
 	if (sg) {
 		if (sk_can_gso(sk)) {
 			/* Small frames wont use a full page:
@@ -1051,6 +1089,12 @@
 			goto do_error;
 	}
 
+	if (tp->mpc) {
+		struct sock *sk_it;
+		mptcp_for_each_sk(tp->mpcb, sk_it)
+			sock_rps_record_flow(sk_it);
+	}
+
 	if (unlikely(tp->repair)) {
 		if (tp->repair_queue == TCP_RECV_QUEUE) {
 			copied = tcp_send_rcvq(sk, msg, size);
@@ -1078,7 +1122,10 @@
 	if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN))
 		goto out_err;
 
-	sg = !!(sk->sk_route_caps & NETIF_F_SG);
+	if (tp->mpc)
+		sg = mptcp_can_sg(sk);
+	else
+		sg = !!(sk->sk_route_caps & NETIF_F_SG);
 
 	while (--iovlen >= 0) {
 		size_t seglen = iov->iov_len;
@@ -1129,8 +1176,15 @@
 
 				/*
 				 * Check whether we can use HW checksum.
+				 *
+				 * If dss-csum is enabled, we do not do hw-csum.
+				 * In case of non-mptcp we check the
+				 * device-capabilities.
+				 * In case of mptcp, hw-csum's will be handled
+				 * later in mptcp_write_xmit.
 				 */
-				if (sk->sk_route_caps & NETIF_F_ALL_CSUM)
+				if (((tp->mpc && !tp->mpcb->dss_csum) || !tp->mpc) &&
+				    (tp->mpc || sk->sk_route_caps & NETIF_F_ALL_CSUM))
 					skb->ip_summed = CHECKSUM_PARTIAL;
 
 				skb_entail(sk, skb);
@@ -1330,6 +1384,11 @@
 
 	struct sk_buff *skb = skb_peek(&sk->sk_receive_queue);
 
+	if (is_meta_sk(sk)) {
+		mptcp_cleanup_rbuf(sk, copied);
+		return;
+	}
+
 	WARN(skb && !before(tp->copied_seq, TCP_SKB_CB(skb)->end_seq),
 	     "cleanup rbuf bug: copied %X seq %X rcvnxt %X\n",
 	     tp->copied_seq, TCP_SKB_CB(skb)->end_seq, tp->rcv_nxt);
@@ -1567,6 +1626,14 @@
 
 	lock_sock(sk);
 
+#ifdef CONFIG_MPTCP
+	if (tp->mpc) {
+		struct sock *sk_it;
+		mptcp_for_each_sk(tp->mpcb, sk_it)
+			sock_rps_record_flow(sk_it);
+	}
+#endif
+
 	err = -ENOTCONN;
 	if (sk->sk_state == TCP_LISTEN)
 		goto out;
@@ -2014,7 +2081,7 @@
   /* TCP_CLOSING	*/ TCP_CLOSING,
 };
 
-static int tcp_close_state(struct sock *sk)
+int tcp_close_state(struct sock *sk)
 {
 	int next = (int)new_state[sk->sk_state];
 	int ns = next & TCP_STATE_MASK;
@@ -2043,8 +2110,12 @@
 	    (TCPF_ESTABLISHED | TCPF_SYN_SENT |
 	     TCPF_SYN_RECV | TCPF_CLOSE_WAIT)) {
 		/* Clear out any half completed packets.  FIN if needed. */
-		if (tcp_close_state(sk))
-			tcp_send_fin(sk);
+		if (tcp_close_state(sk)) {
+			if (!is_meta_sk(sk))
+				tcp_send_fin(sk);
+			else
+				mptcp_send_fin(sk);
+		}
 	}
 }
 EXPORT_SYMBOL(tcp_shutdown);
@@ -2069,6 +2140,11 @@
 	int data_was_unread = 0;
 	int state;
 
+	if (is_meta_sk(sk)) {
+		mptcp_close(sk, timeout);
+		return;
+	}
+
 	lock_sock(sk);
 	sk->sk_shutdown = SHUTDOWN_MASK;
 
@@ -2235,15 +2311,6 @@
 }
 EXPORT_SYMBOL(tcp_close);
 
-/* These states need RST on ABORT according to RFC793 */
-
-static inline bool tcp_need_reset(int state)
-{
-	return (1 << state) &
-	       (TCPF_ESTABLISHED | TCPF_CLOSE_WAIT | TCPF_FIN_WAIT1 |
-		TCPF_FIN_WAIT2 | TCPF_SYN_RECV);
-}
-
 int tcp_disconnect(struct sock *sk, int flags)
 {
 	struct inet_sock *inet = inet_sk(sk);
@@ -2284,6 +2351,50 @@
 	if (!(sk->sk_userlocks & SOCK_BINDADDR_LOCK))
 		inet_reset_saddr(sk);
 
+#ifdef CONFIG_MPTCP
+	if (is_meta_sk(sk)) {
+		struct sock *subsk, *tmpsk;
+		struct tcp_sock *tp = tcp_sk(sk);
+
+		__skb_queue_purge(&tp->mpcb->reinject_queue);
+
+		if (tp->inside_tk_table) {
+			mptcp_hash_remove_bh(tp);
+			reqsk_queue_destroy(&inet_csk(tp->meta_sk)->icsk_accept_queue);
+		}
+
+		local_bh_disable();
+		mptcp_for_each_sk_safe(tp->mpcb, subsk, tmpsk) {
+			/* The socket will get removed from the subsocket-list
+			 * and made non-mptcp by setting mpc to 0.
+			 *
+			 * This is necessary, because tcp_disconnect assumes
+			 * that the connection is completly dead afterwards.
+			 * Thus we need to do a mptcp_del_sock. Due to this call
+			 * we have to make it non-mptcp.
+			 *
+			 * We have to lock the socket, because we set mpc to 0.
+			 * An incoming packet would take the subsocket's lock
+			 * and go on into the receive-path.
+			 * This would be a race.
+			 */
+
+			bh_lock_sock(subsk);
+			mptcp_del_sock(subsk);
+			tcp_sk(subsk)->mpc = 0;
+			mptcp_sub_force_close(subsk);
+			bh_unlock_sock(subsk);
+		}
+		local_bh_enable();
+
+		tp->was_meta_sk = 1;
+		tp->mpc = 0;
+	} else {
+		if (tp->inside_tk_table)
+			mptcp_hash_remove_bh(tp);
+	}
+#endif
+
 	sk->sk_shutdown = 0;
 	sock_reset_flag(sk, SOCK_DONE);
 	tp->srtt = 0;
@@ -2542,6 +2653,13 @@
 					elapsed = tp->keepalive_time - elapsed;
 				else
 					elapsed = 0;
+				if (tp->mpc) {
+					struct sock *sk_it = sk;
+					mptcp_for_each_sk(tp->mpcb, sk_it)
+						if (!(1 << sk->sk_state & (TCPF_CLOSE | TCPF_LISTEN)))
+							inet_csk_reset_keepalive_timer(sk_it, elapsed);
+					break;
+				}
 				inet_csk_reset_keepalive_timer(sk, elapsed);
 			}
 		}
@@ -3039,12 +3157,19 @@
 void tcp_done(struct sock *sk)
 {
 	struct request_sock *req = tcp_sk(sk)->fastopen_rsk;
+	struct tcp_sock *tp = tcp_sk(sk);
 
 	if (sk->sk_state == TCP_SYN_SENT || sk->sk_state == TCP_SYN_RECV)
 		TCP_INC_STATS_BH(sock_net(sk), TCP_MIB_ATTEMPTFAILS);
 
+	WARN_ON(sk->sk_state == TCP_CLOSE);
 	tcp_set_state(sk, TCP_CLOSE);
-	tcp_clear_xmit_timers(sk);
+
+	/* If it is a meta-sk sending mp_fclose we have to maintain the
+	 * rexmit-timer for retransmitting the MP_FCLOSE */
+	if (!tp->mpc || !is_meta_sk(sk) || !tp->send_mp_fclose)
+		tcp_clear_xmit_timers(sk);
+
 	if (req != NULL)
 		reqsk_fastopen_remove(sk, req, false);
 
diff -Naur a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
--- a/net/ipv4/tcp_input.c	2013-09-02 22:46:10.000000000 +0200
+++ b/net/ipv4/tcp_input.c	2013-10-06 18:26:04.356867907 +0200
@@ -74,6 +74,9 @@
 #include <linux/ipsec.h>
 #include <asm/unaligned.h>
 #include <net/netdma.h>
+#include <net/mptcp.h>
+#include <net/mptcp_v4.h>
+#include <net/mptcp_v6.h>
 
 int sysctl_tcp_timestamps __read_mostly = 1;
 int sysctl_tcp_window_scaling __read_mostly = 1;
@@ -99,25 +102,6 @@
 int sysctl_tcp_moderate_rcvbuf __read_mostly = 1;
 int sysctl_tcp_early_retrans __read_mostly = 3;
 
-#define FLAG_DATA		0x01 /* Incoming frame contained data.		*/
-#define FLAG_WIN_UPDATE		0x02 /* Incoming ACK was a window update.	*/
-#define FLAG_DATA_ACKED		0x04 /* This ACK acknowledged new data.		*/
-#define FLAG_RETRANS_DATA_ACKED	0x08 /* "" "" some of which was retransmitted.	*/
-#define FLAG_SYN_ACKED		0x10 /* This ACK acknowledged SYN.		*/
-#define FLAG_DATA_SACKED	0x20 /* New SACK.				*/
-#define FLAG_ECE		0x40 /* ECE in this ACK				*/
-#define FLAG_SLOWPATH		0x100 /* Do not skip RFC checks for window update.*/
-#define FLAG_ORIG_SACK_ACKED	0x200 /* Never retransmitted data are (s)acked	*/
-#define FLAG_SND_UNA_ADVANCED	0x400 /* Snd_una was changed (!= FLAG_DATA_ACKED) */
-#define FLAG_DSACKING_ACK	0x800 /* SACK blocks contained D-SACK info */
-#define FLAG_SACK_RENEGING	0x2000 /* snd_una advanced to a sacked seq */
-#define FLAG_UPDATE_TS_RECENT	0x4000 /* tcp_replace_ts_recent() */
-
-#define FLAG_ACKED		(FLAG_DATA_ACKED|FLAG_SYN_ACKED)
-#define FLAG_NOT_DUP		(FLAG_DATA|FLAG_WIN_UPDATE|FLAG_ACKED)
-#define FLAG_CA_ALERT		(FLAG_DATA_SACKED|FLAG_ECE)
-#define FLAG_FORWARD_PROGRESS	(FLAG_ACKED|FLAG_DATA_SACKED)
-
 #define TCP_REMNANT (TCP_FLAG_FIN|TCP_FLAG_URG|TCP_FLAG_SYN|TCP_FLAG_PSH)
 #define TCP_HP_BITS (~(TCP_RESERVED_BITS|TCP_FLAG_PSH))
 
@@ -322,10 +306,12 @@
 static void tcp_grow_window(struct sock *sk, const struct sk_buff *skb)
 {
 	struct tcp_sock *tp = tcp_sk(sk);
+	struct sock *meta_sk = tp->mpc ? mptcp_meta_sk(sk) : sk;
+	struct tcp_sock *meta_tp = tcp_sk(meta_sk);
 
 	/* Check #1 */
-	if (tp->rcv_ssthresh < tp->window_clamp &&
-	    (int)tp->rcv_ssthresh < tcp_space(sk) &&
+	if (meta_tp->rcv_ssthresh < meta_tp->window_clamp &&
+	    (int)meta_tp->rcv_ssthresh < tcp_space(sk) &&
 	    !sk_under_memory_pressure(sk)) {
 		int incr;
 
@@ -333,14 +319,14 @@
 		 * will fit to rcvbuf in future.
 		 */
 		if (tcp_win_from_space(skb->truesize) <= skb->len)
-			incr = 2 * tp->advmss;
+			incr = 2 * meta_tp->advmss;
 		else
-			incr = __tcp_grow_window(sk, skb);
+			incr = __tcp_grow_window(meta_sk, skb);
 
 		if (incr) {
 			incr = max_t(int, incr, 2 * skb->len);
-			tp->rcv_ssthresh = min(tp->rcv_ssthresh + incr,
-					       tp->window_clamp);
+			meta_tp->rcv_ssthresh = min(meta_tp->rcv_ssthresh + incr,
+					            meta_tp->window_clamp);
 			inet_csk(sk)->icsk_ack.quick |= 1;
 		}
 	}
@@ -393,6 +379,11 @@
 
 	tp->rcv_ssthresh = min(tp->rcv_ssthresh, tp->window_clamp);
 	tp->snd_cwnd_stamp = tcp_time_stamp;
+
+	if (tp->mpc) {
+		mptcp_init_buffer_space(sk);
+		mptcp_update_sndbuf(tp->mpcb);
+	}
 }
 
 /* 5. Recalculate window clamp after socket hit its memory bounds. */
@@ -518,7 +509,10 @@
 		goto new_measure;
 
 	time = tcp_time_stamp - tp->rcvq_space.time;
-	if (time < (tp->rcv_rtt_est.rtt >> 3) || tp->rcv_rtt_est.rtt == 0)
+	if (tp->mpc) {
+		if (mptcp_check_rtt(tp, time))
+			return;
+	} else if (time < (tp->rcv_rtt_est.rtt >> 3) || tp->rcv_rtt_est.rtt == 0)
 		return;
 
 	space = 2 * (tp->copied_seq - tp->rcvq_space.seq);
@@ -716,6 +710,7 @@
 	 * guarantees that rto is higher.
 	 */
 	tcp_bound_rto(sk);
+	mptcp_set_rto(sk);
 }
 
 __u32 tcp_init_cwnd(const struct tcp_sock *tp, const struct dst_entry *dst)
@@ -2914,7 +2909,7 @@
 }
 
 /* If we get here, the whole TSO packet has not been acked. */
-static u32 tcp_tso_acked(struct sock *sk, struct sk_buff *skb)
+u32 tcp_tso_acked(struct sock *sk, struct sk_buff *skb)
 {
 	struct tcp_sock *tp = tcp_sk(sk);
 	u32 packets_acked;
@@ -3009,6 +3004,8 @@
 		 */
 		if (!(scb->tcp_flags & TCPHDR_SYN)) {
 			flag |= FLAG_DATA_ACKED;
+			if (tp->mpc && mptcp_is_data_seq(skb))
+				flag |= MPTCP_FLAG_DATA_ACKED;
 		} else {
 			flag |= FLAG_SYN_ACKED;
 			tp->retrans_stamp = 0;
@@ -3018,6 +3015,7 @@
 			break;
 
 		tcp_unlink_write_queue(skb, sk);
+
 		sk_wmem_free_skb(sk, skb);
 		if (skb == tp->retransmit_skb_hint)
 			tp->retransmit_skb_hint = NULL;
@@ -3104,7 +3102,7 @@
 	return flag;
 }
 
-static void tcp_ack_probe(struct sock *sk)
+void tcp_ack_probe(struct sock *sk)
 {
 	const struct tcp_sock *tp = tcp_sk(sk);
 	struct inet_connection_sock *icsk = inet_csk(sk);
@@ -3140,9 +3138,8 @@
 /* Check that window update is acceptable.
  * The function assumes that snd_una<=ack<=snd_next.
  */
-static inline bool tcp_may_update_window(const struct tcp_sock *tp,
-					const u32 ack, const u32 ack_seq,
-					const u32 nwin)
+bool tcp_may_update_window(const struct tcp_sock *tp, const u32 ack,
+			   const u32 ack_seq, const u32 nwin)
 {
 	return	after(ack, tp->snd_una) ||
 		after(ack_seq, tp->snd_wl1) ||
@@ -3261,7 +3258,7 @@
 }
 
 /* This routine deals with incoming acks, but not outgoing ones. */
-static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag)
+static int tcp_ack(struct sock *sk, struct sk_buff *skb, int flag)
 {
 	struct inet_connection_sock *icsk = inet_csk(sk);
 	struct tcp_sock *tp = tcp_sk(sk);
@@ -3350,6 +3347,19 @@
 	/* See if we can take anything off of the retransmit queue. */
 	acked = tp->packets_out;
 	flag |= tcp_clean_rtx_queue(sk, prior_fackets, prior_snd_una);
+
+	if (tp->mpc) {
+		flag |= mptcp_fallback_infinite(sk, flag);
+	
+		if (flag & MPTCP_FLAG_SEND_RESET) {
+			pr_err("%s resetting flow\n", __func__);
+			mptcp_send_reset(sk);
+			goto invalid_ack;
+		}
+	
+	mptcp_clean_rtx_infinite(skb, sk);
+	}
+
 	acked -= tp->packets_out;
 
 	if (tcp_ack_is_dubious(sk, flag)) {
@@ -3416,8 +3426,9 @@
  * the fast version below fails.
  */
 void tcp_parse_options(const struct sk_buff *skb,
-		       struct tcp_options_received *opt_rx, int estab,
-		       struct tcp_fastopen_cookie *foc)
+		       struct tcp_options_received *opt_rx,
+		       struct mptcp_options_received *mopt,
+		       int estab, struct tcp_fastopen_cookie *foc)
 {
 	const unsigned char *ptr;
 	const struct tcphdr *th = tcp_hdr(skb);
@@ -3500,6 +3511,10 @@
 				 */
 				break;
 #endif
+			case TCPOPT_MPTCP:
+				mptcp_parse_options(ptr - 2, opsize, opt_rx,
+						    mopt, skb);
+				break;
 			case TCPOPT_EXP:
 				/* Fast Open option shares code 254 using a
 				 * 16 bits magic number. It's valid only in
@@ -3561,8 +3576,8 @@
 		if (tcp_parse_aligned_timestamp(tp, th))
 			return true;
 	}
-
-	tcp_parse_options(skb, &tp->rx_opt, 1, NULL);
+	tcp_parse_options(skb, &tp->rx_opt, tp->mpc ? &tp->mptcp->rx_opt : NULL,
+			  1, NULL);
 	if (tp->rx_opt.saw_tstamp && tp->rx_opt.rcv_tsecr)
 		tp->rx_opt.rcv_tsecr -= tp->tsoffset;
 
@@ -3732,6 +3747,8 @@
 	case TCP_ESTABLISHED:
 		/* Move to CLOSE_WAIT */
 		tcp_set_state(sk, TCP_CLOSE_WAIT);
+		if (tp->mpc)
+			mptcp_sub_close_passive(sk);
 		dst = __sk_dst_get(sk);
 		if (!dst || !dst_metric(dst, RTAX_QUICKACK))
 			inet_csk(sk)->icsk_ack.pingpong = 1;
@@ -3756,6 +3773,13 @@
 		tcp_set_state(sk, TCP_CLOSING);
 		break;
 	case TCP_FIN_WAIT2:
+		if (tp->mpc) {
+			/* The socket will get closed by mptcp_data_ready.
+			 * We first have to process all data-sequences.
+			 */
+			tp->close_it = 1;
+			break;
+		}
 		/* Received a FIN -- send ACK and enter TIME_WAIT. */
 		tcp_send_ack(sk);
 		tcp_time_wait(sk, TCP_TIME_WAIT, 0);
@@ -3780,6 +3804,10 @@
 	if (!sock_flag(sk, SOCK_DEAD)) {
 		sk->sk_state_change(sk);
 
+		/* Don't wake up MPTCP-subflows */
+		if (tp->mpc)
+			return;
+
 		/* Do not send POLL_HUP for half duplex close. */
 		if (sk->sk_shutdown == SHUTDOWN_MASK ||
 		    sk->sk_state == TCP_CLOSE)
@@ -3977,7 +4005,11 @@
 			tcp_dsack_extend(sk, TCP_SKB_CB(skb)->seq, dsack);
 		}
 
-		if (!after(TCP_SKB_CB(skb)->end_seq, tp->rcv_nxt)) {
+		/* In case of MPTCP, the segment may be empty if it's a
+		 * non-data DATA_FIN. (see beginning of tcp_data_queue)
+		 */
+		if (!after(TCP_SKB_CB(skb)->end_seq, tp->rcv_nxt) &&
+		    !(tp->mpc && TCP_SKB_CB(skb)->end_seq == TCP_SKB_CB(skb)->seq)) {
 			SOCK_DEBUG(sk, "ofo packet was already received\n");
 			__skb_unlink(skb, &tp->out_of_order_queue);
 			__kfree_skb(skb);
@@ -4001,6 +4033,9 @@
 static int tcp_try_rmem_schedule(struct sock *sk, struct sk_buff *skb,
 				 unsigned int size)
 {
+	if (tcp_sk(sk)->mpc)
+		sk = mptcp_meta_sk(sk);
+
 	if (atomic_read(&sk->sk_rmem_alloc) > sk->sk_rcvbuf ||
 	    !sk_rmem_schedule(sk, skb, size)) {
 
@@ -4031,15 +4066,16 @@
  * Better try to coalesce them right now to avoid future collapses.
  * Returns true if caller should free @from instead of queueing it
  */
-static bool tcp_try_coalesce(struct sock *sk,
-			     struct sk_buff *to,
-			     struct sk_buff *from,
-			     bool *fragstolen)
+bool tcp_try_coalesce(struct sock *sk, struct sk_buff *to, struct sk_buff *from,
+		      bool *fragstolen)
 {
 	int delta;
 
 	*fragstolen = false;
 
+	if (tcp_sk(sk)->mpc && !is_meta_sk(sk))
+		return false;
+
 	if (tcp_hdr(from)->fin)
 		return false;
 
@@ -4128,7 +4164,9 @@
 
 	/* Do skb overlap to previous one? */
 	if (skb1 && before(seq, TCP_SKB_CB(skb1)->end_seq)) {
-		if (!after(end_seq, TCP_SKB_CB(skb1)->end_seq)) {
+		/* MPTCP allows non-data data-fin to be in the ofo-queue */
+		if (!after(end_seq, TCP_SKB_CB(skb1)->end_seq) &&
+		    !(tp->mpc && end_seq == seq)) {
 			/* All the bits are present. Drop. */
 			NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPOFOMERGE);
 			__kfree_skb(skb);
@@ -4166,6 +4204,9 @@
 					 end_seq);
 			break;
 		}
+		/* MPTCP allows non-data data-fin to be in the ofo-queue */
+		if (tp->mpc && TCP_SKB_CB(skb1)->seq == TCP_SKB_CB(skb1)->end_seq)
+			continue;
 		__skb_unlink(skb1, &tp->out_of_order_queue);
 		tcp_dsack_extend(sk, TCP_SKB_CB(skb1)->seq,
 				 TCP_SKB_CB(skb1)->end_seq);
@@ -4181,8 +4222,8 @@
 		skb_set_owner_r(skb, sk);
 }
 
-static int __must_check tcp_queue_rcv(struct sock *sk, struct sk_buff *skb, int hdrlen,
-		  bool *fragstolen)
+int __must_check tcp_queue_rcv(struct sock *sk, struct sk_buff *skb, int hdrlen,
+			       bool *fragstolen)
 {
 	int eaten;
 	struct sk_buff *tail = skb_peek_tail(&sk->sk_receive_queue);
@@ -4244,7 +4285,10 @@
 	int eaten = -1;
 	bool fragstolen = false;
 
-	if (TCP_SKB_CB(skb)->seq == TCP_SKB_CB(skb)->end_seq)
+	/* If no data is present, but a data_fin is in the options, we still
+	 * have to call mptcp_queue_skb later on. */
+	if (TCP_SKB_CB(skb)->seq == TCP_SKB_CB(skb)->end_seq &&
+	    !(tp->mpc && mptcp_is_data_fin(skb)))
 		goto drop;
 
 	skb_dst_drop(skb);
@@ -4290,7 +4334,7 @@
 			eaten = tcp_queue_rcv(sk, skb, 0, &fragstolen);
 		}
 		tp->rcv_nxt = TCP_SKB_CB(skb)->end_seq;
-		if (skb->len)
+		if (skb->len || mptcp_is_data_fin(skb))
 			tcp_event_data_recv(sk, skb);
 		if (th->fin)
 			tcp_fin(sk);
@@ -4312,7 +4356,11 @@
 
 		if (eaten > 0)
 			kfree_skb_partial(skb, fragstolen);
-		if (!sock_flag(sk, SOCK_DEAD))
+		if (!sock_flag(sk, SOCK_DEAD) || tp->mpc)
+			/* MPTCP: we always have to call data_ready, because
+			 * we may be about to receive a data-fin, which still
+			 * must get queued.
+			 */
 			sk->sk_data_ready(sk, 0);
 		return;
 	}
@@ -4386,6 +4434,9 @@
 	struct sk_buff *skb, *n;
 	bool end_of_skbs;
 
+	if (tcp_sk(sk)->mpc)
+		return;
+
 	/* First, check that queue is collapsible and find
 	 * the point where collapsing can be useful. */
 	skb = head;
@@ -4491,7 +4542,7 @@
 	struct sk_buff *head;
 	u32 start, end;
 
-	if (skb == NULL)
+	if (skb == NULL || tp->mpc)
 		return;
 
 	start = TCP_SKB_CB(skb)->seq;
@@ -4536,6 +4587,18 @@
 	struct tcp_sock *tp = tcp_sk(sk);
 	bool res = false;
 
+	if (is_meta_sk(sk)) {
+		if (!skb_queue_empty(&tp->out_of_order_queue)) {
+			NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_OFOPRUNED);
+			mptcp_purge_ofo_queue(tp);
+
+			/* No sack at the mptcp-level */
+			sk_mem_reclaim(sk);
+			res = 1;
+		}
+		return res;
+	}
+
 	if (!skb_queue_empty(&tp->out_of_order_queue)) {
 		NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_OFOPRUNED);
 		__skb_queue_purge(&tp->out_of_order_queue);
@@ -4644,9 +4707,46 @@
 		return false;
 
 	/* If we filled the congestion window, do not expand.  */
-	if (tp->packets_out >= tp->snd_cwnd)
+	if (!tp->mpc && tp->packets_out >= tp->snd_cwnd)
 		return false;
 
+#ifdef CONFIG_MPTCP
+	if (tp->mpc) {
+		struct sock *sk_it;
+		int cnt_backups = 0;
+		int backup_available = 0;
+
+		/* For MPTCP we look for a subsocket that could send data.
+		 * If we found one, then we update the send-buffer.
+		 */
+		mptcp_for_each_sk(tp->mpcb, sk_it) {
+			struct tcp_sock *tp_it = tcp_sk(sk_it);
+
+			if (!mptcp_sk_can_send(sk_it))
+				continue;
+
+			/* Backup-flows have to be counted - if there is no other
+			 * subflow we take the backup-flow into account. */
+			if (tp_it->mptcp->rcv_low_prio || tp_it->mptcp->low_prio) {
+				cnt_backups++;
+			}
+
+			if (tp_it->packets_out < tp_it->snd_cwnd) {
+				if (tp_it->mptcp->rcv_low_prio || tp_it->mptcp->low_prio) {
+					backup_available = 1;
+					continue;
+				}
+				return 1;
+			}
+		}
+
+		/* Backup-flow is available for sending - update send-buffer */
+		if (tp->mpcb->cnt_established == cnt_backups && backup_available)
+			return 1;
+		return 0;
+	}
+#endif
+
 	return true;
 }
 
@@ -4659,17 +4759,34 @@
 static void tcp_new_space(struct sock *sk)
 {
 	struct tcp_sock *tp = tcp_sk(sk);
+	struct sock *meta_sk = tp->mpc ? mptcp_meta_sk(sk) : sk;
 
-	if (tcp_should_expand_sndbuf(sk)) {
+	if (tcp_should_expand_sndbuf(meta_sk)) {
 		int sndmem = SKB_TRUESIZE(max_t(u32,
 						tp->rx_opt.mss_clamp,
 						tp->mss_cache) +
 					  MAX_TCP_HEADER);
-		int demanded = max_t(unsigned int, tp->snd_cwnd,
-				     tp->reordering + 1);
+		int demanded;
+
+		if (tp->mpc)
+			demanded = mptcp_check_snd_buf(tp);
+		else
+			demanded = max_t(unsigned int, tp->snd_cwnd,
+					 tp->reordering + 1);
+
+		/* MPTCP: After this, sndmem is the new contribution of the
+		 * current subflow to the aggregate sndbuf
+		 */
 		sndmem *= 2 * demanded;
-		if (sndmem > sk->sk_sndbuf)
+		if (sndmem > sk->sk_sndbuf) {
+			int old_sndbuf = sk->sk_sndbuf;
 			sk->sk_sndbuf = min(sndmem, sysctl_tcp_wmem[2]);
+			/* MPTCP: ok, the subflow sndbuf has grown, reflect
+			 * this in the aggregate buffer.
+			 */
+			if (tp->mpc && old_sndbuf != sk->sk_sndbuf)
+				mptcp_update_sndbuf(tp->mpcb);
+		}
 		tp->snd_cwnd_stamp = tcp_time_stamp;
 	}
 
@@ -4680,8 +4797,9 @@
 {
 	if (sock_flag(sk, SOCK_QUEUE_SHRUNK)) {
 		sock_reset_flag(sk, SOCK_QUEUE_SHRUNK);
-		if (sk->sk_socket &&
-		    test_bit(SOCK_NOSPACE, &sk->sk_socket->flags))
+		if (tcp_sk(sk)->mpc ||
+		    (sk->sk_socket &&
+			test_bit(SOCK_NOSPACE, &sk->sk_socket->flags)))
 			tcp_new_space(sk);
 	}
 }
@@ -4806,6 +4924,10 @@
 {
 	struct tcp_sock *tp = tcp_sk(sk);
 
+	/* MPTCP urgent data is not yet supported */
+	if (tp->mpc)
+		return;
+
 	/* Check if we get a new urgent pointer - normally not. */
 	if (th->urg)
 		tcp_check_urg(sk, th);
@@ -4818,8 +4940,10 @@
 		/* Is the urgent pointer pointing into this packet? */
 		if (ptr < skb->len) {
 			u8 tmp;
+
 			if (skb_copy_bits(skb, ptr, &tmp, 1))
 				BUG();
+
 			tp->urg_data = TCP_URG_VALID | tmp;
 			if (!sock_flag(sk, SOCK_DEAD))
 				sk->sk_data_ready(sk, 0);
@@ -4873,8 +4997,7 @@
 }
 
 #ifdef CONFIG_NET_DMA
-static bool tcp_dma_try_early_copy(struct sock *sk, struct sk_buff *skb,
-				  int hlen)
+bool tcp_dma_try_early_copy(struct sock *sk, struct sk_buff *skb, int hlen)
 {
 	struct tcp_sock *tp = tcp_sk(sk);
 	int chunk = skb->len - hlen;
@@ -4983,9 +5106,15 @@
 		goto discard;
 	}
 
+	/* If valid: post process the received MPTCP options. */
+	if (tp->mpc && mptcp_handle_options(sk, th, skb))
+		goto discard;
+
 	return true;
 
 discard:
+	if (tp->mpc)
+		mptcp_reset_mopt(tp);
 	__kfree_skb(skb);
 	return false;
 }
@@ -5037,6 +5166,10 @@
 
 	tp->rx_opt.saw_tstamp = 0;
 
+	/* MPTCP: force slowpath. */
+	if (tp->mpc)
+		goto slow_path;
+
 	/*	pred_flags is 0xS?10 << 16 + snd_wnd
 	 *	if header_prediction is to be made
 	 *	'S' will always be tp->tcp_header_len >> 2
@@ -5282,7 +5415,7 @@
 		/* Get original SYNACK MSS value if user MSS sets mss_clamp */
 		tcp_clear_options(&opt);
 		opt.user_mss = opt.mss_clamp = 0;
-		tcp_parse_options(synack, &opt, 0, NULL);
+		tcp_parse_options(synack, &opt, NULL, 0, NULL);
 		mss = opt.mss_clamp;
 	}
 
@@ -5317,8 +5450,11 @@
 	struct tcp_sock *tp = tcp_sk(sk);
 	struct tcp_fastopen_cookie foc = { .len = -1 };
 	int saved_clamp = tp->rx_opt.mss_clamp;
+	struct mptcp_options_received mopt;
+	mptcp_init_mp_opt(&mopt);
 
-	tcp_parse_options(skb, &tp->rx_opt, 0, &foc);
+	tcp_parse_options(skb, &tp->rx_opt,
+			  tp->mpc ? &tp->mptcp->rx_opt : &mopt, 0, &foc);
 	if (tp->rx_opt.saw_tstamp && tp->rx_opt.rcv_tsecr)
 		tp->rx_opt.rcv_tsecr -= tp->tsoffset;
 
@@ -5365,6 +5501,21 @@
 		if (!th->syn)
 			goto discard_and_undo;
 
+		if (tp->request_mptcp || tp->mpc) {
+			int ret;
+			ret = mptcp_rcv_synsent_state_process(sk, &sk,
+							      skb, &mopt);
+
+			/* May have changed if we support MPTCP */
+			tp = tcp_sk(sk);
+			icsk = inet_csk(sk);
+
+			if (ret == 1)
+				goto reset_and_undo;
+			if (ret == 2)
+				goto discard;
+		}
+
 		/* rfc793:
 		 *   "If the SYN bit is on ...
 		 *    are acceptable then ...
@@ -5377,6 +5528,15 @@
 		tcp_init_wl(tp, TCP_SKB_CB(skb)->seq);
 		tcp_ack(sk, skb, FLAG_SLOWPATH);
 
+		if (tp->mpc && !is_master_tp(tp)) {
+			/* Timer for repeating the ACK until an answer
+			 * arrives. Used only when establishing an additional
+			 * subflow inside of an MPTCP connection.
+			 */
+			sk_reset_timer(sk, &tp->mptcp->mptcp_ack_timer,
+				       jiffies + icsk->icsk_rto);
+		}
+
 		/* Ok.. it's good. Set up sequence numbers and
 		 * move to established.
 		 */
@@ -5403,6 +5563,11 @@
 			tp->tcp_header_len = sizeof(struct tcphdr);
 		}
 
+		if (tp->mpc) {
+			tp->tcp_header_len += MPTCP_SUB_LEN_DSM_ALIGN;
+			tp->advmss -= MPTCP_SUB_LEN_DSM_ALIGN;
+		}
+
 		if (tcp_is_sack(tp) && sysctl_tcp_fack)
 			tcp_enable_fack(tp);
 
@@ -5423,7 +5588,9 @@
 		    tcp_rcv_fastopen_synack(sk, skb, &foc))
 			return -1;
 
-		if (sk->sk_write_pending ||
+		/* With MPTCP we cannot send data on the third ack due to the
+		 * lack of option-space */
+		if ((sk->sk_write_pending && !tp->mpc) ||
 		    icsk->icsk_accept_queue.rskq_defer_accept ||
 		    icsk->icsk_ack.pingpong) {
 			/* Save one ACK. Data will be ready after
@@ -5465,6 +5632,7 @@
 	    tcp_paws_reject(&tp->rx_opt, 0))
 		goto discard_and_undo;
 
+	/* TODO - check this here for MPTCP */
 	if (th->syn) {
 		/* We see SYN without ACK. It is attempt of
 		 * simultaneous connect with crossed SYNs.
@@ -5481,6 +5649,11 @@
 			tp->tcp_header_len = sizeof(struct tcphdr);
 		}
 
+		if (tp->mpc) {
+			tp->tcp_header_len += MPTCP_SUB_LEN_DSM_ALIGN;
+			tp->advmss -= MPTCP_SUB_LEN_DSM_ALIGN;
+		}
+
 		tp->rcv_nxt = TCP_SKB_CB(skb)->seq + 1;
 		tp->rcv_wup = TCP_SKB_CB(skb)->seq + 1;
 
@@ -5589,6 +5762,10 @@
 
 	case TCP_SYN_SENT:
 		queued = tcp_rcv_synsent_state_process(sk, skb, th, len);
+		if (is_meta_sk(sk)) {
+			sk = tcp_sk(sk)->mpcb->master_sk;
+			tp = tcp_sk(sk);
+		}
 		if (queued >= 0)
 			return queued;
 
@@ -5596,6 +5773,8 @@
 		tcp_urg(sk, skb, th);
 		__kfree_skb(skb);
 		tcp_data_snd_check(sk);
+		if (tp->mpc && is_master_tp(tp))
+			bh_unlock_sock(sk);
 		return 0;
 	}
 
@@ -5657,6 +5836,8 @@
 
 		if (tp->rx_opt.tstamp_ok)
 			tp->advmss -= TCPOLEN_TSTAMP_ALIGNED;
+		if (tp->mpc)
+			tp->advmss -= MPTCP_SUB_LEN_DSM_ALIGN;
 
 		if (req) {
 			/* Re-arm the timer because data may have been sent out.
@@ -5676,6 +5857,14 @@
 
 		tcp_initialize_rcv_mss(sk);
 		tcp_fast_path_on(tp);
+
+		/* Send an ACK when establishing a new
+		 * MPTCP subflow, i.e. using an MP_JOIN
+		 * subtype.
+		 */
+		if (tp->mpc && !is_master_tp(tp))
+			tcp_send_ack(sk);
+
 		break;
 
 	case TCP_FIN_WAIT1: {
@@ -5714,6 +5903,9 @@
 			/* Wake up lingering close() */
 			sk->sk_state_change(sk);
 			break;
+		case TCP_CLOSE:
+			if (tp->mp_killed)
+				goto discard;
 		}
 
 		if (tp->linger2 < 0 ||
@@ -5727,7 +5919,8 @@
 		tmo = tcp_fin_time(sk);
 		if (tmo > TCP_TIMEWAIT_LEN) {
 			inet_csk_reset_keepalive_timer(sk, tmo - TCP_TIMEWAIT_LEN);
-		} else if (th->fin || sock_owned_by_user(sk)) {
+		} else if (th->fin || mptcp_is_data_fin(skb) ||
+			   sock_owned_by_user(sk)) {
 			/* Bad case. We could lose such FIN otherwise.
 			 * It is not a big problem, but it looks confusing
 			 * and not so rare event. We still can lose it now,
@@ -5776,7 +5969,10 @@
 		 */
 		if (sk->sk_shutdown & RCV_SHUTDOWN) {
 			if (TCP_SKB_CB(skb)->end_seq != TCP_SKB_CB(skb)->seq &&
-			    after(TCP_SKB_CB(skb)->end_seq - th->fin, tp->rcv_nxt)) {
+			    after(TCP_SKB_CB(skb)->end_seq - th->fin, tp->rcv_nxt) &&
+			    !tp->mpc) {
+				/* In case of mptcp, the reset is handled by
+				 * mptcp_rcv_state_process */
 				NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPABORTONDATA);
 				tcp_reset(sk);
 				return 1;
diff -Naur a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
--- a/net/ipv4/tcp_ipv4.c	2013-09-02 22:46:10.000000000 +0200
+++ b/net/ipv4/tcp_ipv4.c	2013-10-06 18:26:04.372867706 +0200
@@ -67,6 +67,8 @@
 #include <net/icmp.h>
 #include <net/inet_hashtables.h>
 #include <net/tcp.h>
+#include <net/mptcp.h>
+#include <net/mptcp_v4.h>
 #include <net/transp_v6.h>
 #include <net/ipv6.h>
 #include <net/inet_common.h>
@@ -99,7 +101,7 @@
 struct inet_hashinfo tcp_hashinfo;
 EXPORT_SYMBOL(tcp_hashinfo);
 
-static inline __u32 tcp_v4_init_sequence(const struct sk_buff *skb)
+__u32 tcp_v4_init_sequence(const struct sk_buff *skb)
 {
 	return secure_tcp_sequence_number(ip_hdr(skb)->daddr,
 					  ip_hdr(skb)->saddr,
@@ -333,7 +335,7 @@
 	struct inet_sock *inet;
 	const int type = icmp_hdr(icmp_skb)->type;
 	const int code = icmp_hdr(icmp_skb)->code;
-	struct sock *sk;
+	struct sock *sk, *meta_sk;
 	struct sk_buff *skb;
 	struct request_sock *req;
 	__u32 seq;
@@ -357,13 +359,19 @@
 		return;
 	}
 
-	bh_lock_sock(sk);
+	tp = tcp_sk(sk);
+	if (tp->mpc)
+		meta_sk = mptcp_meta_sk(sk);
+	else
+		meta_sk = sk;
+
+	bh_lock_sock(meta_sk);
 	/* If too many ICMPs get dropped on busy
 	 * servers this needs to be solved differently.
 	 * We do take care of PMTU discovery (RFC1191) special case :
 	 * we can receive locally generated ICMP messages while socket is held.
 	 */
-	if (sock_owned_by_user(sk)) {
+	if (sock_owned_by_user(meta_sk)) {
 		if (!(type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED))
 			NET_INC_STATS_BH(net, LINUX_MIB_LOCKDROPPEDICMPS);
 	}
@@ -376,7 +384,6 @@
 	}
 
 	icsk = inet_csk(sk);
-	tp = tcp_sk(sk);
 	req = tp->fastopen_rsk;
 	seq = ntohl(th->seq);
 	if (sk->sk_state != TCP_LISTEN &&
@@ -410,11 +417,14 @@
 				goto out;
 
 			tp->mtu_info = info;
-			if (!sock_owned_by_user(sk)) {
+			if (!sock_owned_by_user(meta_sk)) {
 				tcp_v4_mtu_reduced(sk);
 			} else {
 				if (!test_and_set_bit(TCP_MTU_REDUCED_DEFERRED, &tp->tsq_flags))
 					sock_hold(sk);
+				if (tp->mpc &&
+				    !test_and_set_bit(TCP_MTU_REDUCED_DEFERRED, &tcp_sk(meta_sk)->tsq_flags))
+					sock_hold(meta_sk);
 			}
 			goto out;
 		}
@@ -430,7 +440,7 @@
 
 		/* XXX (TFO) - revisit the following logic for TFO */
 
-		if (sock_owned_by_user(sk))
+		if (sock_owned_by_user(meta_sk))
 			break;
 
 		icsk->icsk_backoff--;
@@ -472,7 +482,7 @@
 	switch (sk->sk_state) {
 		struct request_sock *req, **prev;
 	case TCP_LISTEN:
-		if (sock_owned_by_user(sk))
+		if (sock_owned_by_user(meta_sk))
 			goto out;
 
 		req = inet_csk_search_req(sk, &prev, th->dest,
@@ -505,7 +515,7 @@
 			       It can f.e. if SYNs crossed,
 			       or Fast Open.
 			     */
-		if (!sock_owned_by_user(sk)) {
+		if (!sock_owned_by_user(meta_sk)) {
 			sk->sk_err = err;
 
 			sk->sk_error_report(sk);
@@ -534,7 +544,7 @@
 	 */
 
 	inet = inet_sk(sk);
-	if (!sock_owned_by_user(sk) && inet->recverr) {
+	if (!sock_owned_by_user(meta_sk) && inet->recverr) {
 		sk->sk_err = err;
 		sk->sk_error_report(sk);
 	} else	{ /* Only an error on timeout */
@@ -542,7 +552,7 @@
 	}
 
 out:
-	bh_unlock_sock(sk);
+	bh_unlock_sock(meta_sk);
 	sock_put(sk);
 }
 
@@ -584,7 +594,7 @@
  *	Exception: precedence violation. We do not implement it in any case.
  */
 
-static void tcp_v4_send_reset(struct sock *sk, struct sk_buff *skb)
+void tcp_v4_send_reset(struct sock *sk, struct sk_buff *skb)
 {
 	const struct tcphdr *th = tcp_hdr(skb);
 	struct {
@@ -708,10 +718,10 @@
    outside socket context is ugly, certainly. What can I do?
  */
 
-static void tcp_v4_send_ack(struct sk_buff *skb, u32 seq, u32 ack,
+static void tcp_v4_send_ack(struct sk_buff *skb, u32 seq, u32 ack, u32 data_ack,
 			    u32 win, u32 tsval, u32 tsecr, int oif,
 			    struct tcp_md5sig_key *key,
-			    int reply_flags, u8 tos)
+			    int reply_flags, u8 tos, int mptcp)
 {
 	const struct tcphdr *th = tcp_hdr(skb);
 	struct {
@@ -720,6 +730,10 @@
 #ifdef CONFIG_TCP_MD5SIG
 			   + (TCPOLEN_MD5SIG_ALIGNED >> 2)
 #endif
+#ifdef CONFIG_MPTCP
+			   + ((MPTCP_SUB_LEN_DSS >> 2) +
+			      (MPTCP_SUB_LEN_ACK >> 2))
+#endif
 			];
 	} rep;
 	struct ip_reply_arg arg;
@@ -764,6 +778,21 @@
 				    ip_hdr(skb)->daddr, &rep.th);
 	}
 #endif
+#ifdef CONFIG_MPTCP
+	if (mptcp) {
+		int offset = (tsecr) ? 3 : 0;
+		/* Construction of 32-bit data_ack */
+		rep.opt[offset++] = htonl((TCPOPT_MPTCP << 24) |
+					  ((MPTCP_SUB_LEN_DSS + MPTCP_SUB_LEN_ACK) << 16) |
+					  (0x20 << 8) |
+					  (0x01));
+		rep.opt[offset] = htonl(data_ack);
+
+		arg.iov[0].iov_len += MPTCP_SUB_LEN_DSS + MPTCP_SUB_LEN_ACK;
+		rep.th.doff = arg.iov[0].iov_len / 4;
+	}
+#endif /* CONFIG_MPTCP */
+
 	arg.flags = reply_flags;
 	arg.csum = csum_tcpudp_nofold(ip_hdr(skb)->daddr,
 				      ip_hdr(skb)->saddr, /* XXX */
@@ -782,36 +811,44 @@
 {
 	struct inet_timewait_sock *tw = inet_twsk(sk);
 	struct tcp_timewait_sock *tcptw = tcp_twsk(sk);
+	u32 data_ack = 0;
+	int mptcp = 0;
+
+	if (tcptw->mptcp_tw && tcptw->mptcp_tw->meta_tw) {
+		data_ack = (u32)tcptw->mptcp_tw->rcv_nxt;
+		mptcp = 1;
+	}
 
 	tcp_v4_send_ack(skb, tcptw->tw_snd_nxt, tcptw->tw_rcv_nxt,
+			data_ack,
 			tcptw->tw_rcv_wnd >> tw->tw_rcv_wscale,
 			tcp_time_stamp + tcptw->tw_ts_offset,
 			tcptw->tw_ts_recent,
 			tw->tw_bound_dev_if,
 			tcp_twsk_md5_key(tcptw),
 			tw->tw_transparent ? IP_REPLY_ARG_NOSRCCHECK : 0,
-			tw->tw_tos
+			tw->tw_tos, mptcp
 			);
 
 	inet_twsk_put(tw);
 }
 
-static void tcp_v4_reqsk_send_ack(struct sock *sk, struct sk_buff *skb,
-				  struct request_sock *req)
+void tcp_v4_reqsk_send_ack(struct sock *sk, struct sk_buff *skb,
+			   struct request_sock *req)
 {
 	/* sk->sk_state == TCP_LISTEN -> for regular TCP_SYN_RECV
 	 * sk->sk_state == TCP_SYN_RECV -> for Fast Open.
 	 */
 	tcp_v4_send_ack(skb, (sk->sk_state == TCP_LISTEN) ?
 			tcp_rsk(req)->snt_isn + 1 : tcp_sk(sk)->snd_nxt,
-			tcp_rsk(req)->rcv_nxt, req->rcv_wnd,
+			tcp_rsk(req)->rcv_nxt, 0, req->rcv_wnd,
 			tcp_time_stamp,
 			req->ts_recent,
 			0,
 			tcp_md5_do_lookup(sk, (union tcp_md5_addr *)&ip_hdr(skb)->daddr,
 					  AF_INET),
 			inet_rsk(req)->no_srccheck ? IP_REPLY_ARG_NOSRCCHECK : 0,
-			ip_hdr(skb)->tos);
+			ip_hdr(skb)->tos, 0);
 }
 
 /*
@@ -819,10 +856,9 @@
  *	This still operates on a request_sock only, not on a big
  *	socket.
  */
-static int tcp_v4_send_synack(struct sock *sk, struct dst_entry *dst,
-			      struct request_sock *req,
-			      u16 queue_mapping,
-			      bool nocache)
+int tcp_v4_send_synack(struct sock *sk, struct dst_entry *dst,
+		       struct request_sock *req, u16 queue_mapping,
+		       bool nocache)
 {
 	const struct inet_request_sock *ireq = inet_rsk(req);
 	struct flowi4 fl4;
@@ -850,7 +886,7 @@
 	return err;
 }
 
-static int tcp_v4_rtx_synack(struct sock *sk, struct request_sock *req)
+int tcp_v4_rtx_synack(struct sock *sk, struct request_sock *req)
 {
 	int res = tcp_v4_send_synack(sk, NULL, req, 0, false);
 
@@ -862,7 +898,7 @@
 /*
  *	IPv4 request_sock destructor.
  */
-static void tcp_v4_reqsk_destructor(struct request_sock *req)
+void tcp_v4_reqsk_destructor(struct request_sock *req)
 {
 	kfree(inet_rsk(req)->opt);
 }
@@ -902,7 +938,7 @@
 /*
  * Save and compile IPv4 options into the request_sock if needed.
  */
-static struct ip_options_rcu *tcp_v4_save_options(struct sk_buff *skb)
+struct ip_options_rcu *tcp_v4_save_options(struct sk_buff *skb)
 {
 	const struct ip_options *opt = &(IPCB(skb)->opt);
 	struct ip_options_rcu *dopt = NULL;
@@ -1440,6 +1476,7 @@
 int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb)
 {
 	struct tcp_options_received tmp_opt;
+	struct mptcp_options_received mopt;
 	struct request_sock *req;
 	struct inet_request_sock *ireq;
 	struct tcp_sock *tp = tcp_sk(sk);
@@ -1454,6 +1491,22 @@
 	struct sk_buff *skb_synack;
 	int do_fastopen;
 
+	tcp_clear_options(&tmp_opt);
+	tmp_opt.mss_clamp = TCP_MSS_DEFAULT;
+	tmp_opt.user_mss  = tp->rx_opt.user_mss;
+	mptcp_init_mp_opt(&mopt);
+	tcp_parse_options(skb, &tmp_opt, &mopt, 0, want_cookie ? NULL : &foc);
+
+#ifdef CONFIG_MPTCP
+	/* MPTCP structures not initialized, so clear MPTCP fields */
+	if  (mptcp_init_failed)
+		mptcp_init_mp_opt(&mopt);
+
+	if (mopt.is_mp_join)
+		return mptcp_do_join_short(skb, &mopt, &tmp_opt, sock_net(sk));
+	if (mopt.drop_me)
+		goto drop;
+#endif
 	/* Never answer to SYNs send to broadcast or multicast */
 	if (skb_rtable(skb)->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))
 		goto drop;
@@ -1478,7 +1531,20 @@
 		goto drop;
 	}
 
-	req = inet_reqsk_alloc(&tcp_request_sock_ops);
+#ifdef CONFIG_MPTCP
+	if (mopt.saw_mpc) {
+		req = inet_reqsk_alloc(&mptcp_request_sock_ops);
+
+		if (!req)
+			goto drop;
+
+		mptcp_rsk(req)->mpcb = NULL;
+		mptcp_rsk(req)->dss_csum = mopt.dss_csum;
+		mptcp_rsk(req)->collide_tk.pprev = NULL;
+	} else
+#endif
+		req = inet_reqsk_alloc(&tcp_request_sock_ops);
+
 	if (!req)
 		goto drop;
 
@@ -1486,17 +1552,15 @@
 	tcp_rsk(req)->af_specific = &tcp_request_sock_ipv4_ops;
 #endif
 
-	tcp_clear_options(&tmp_opt);
-	tmp_opt.mss_clamp = TCP_MSS_DEFAULT;
-	tmp_opt.user_mss  = tp->rx_opt.user_mss;
-	tcp_parse_options(skb, &tmp_opt, 0, want_cookie ? NULL : &foc);
-
 	if (want_cookie && !tmp_opt.saw_tstamp)
 		tcp_clear_options(&tmp_opt);
 
 	tmp_opt.tstamp_ok = tmp_opt.saw_tstamp;
 	tcp_openreq_init(req, &tmp_opt, skb);
 
+	if (mopt.saw_mpc)
+		mptcp_reqsk_new_mptcp(req, &tmp_opt, &mopt, skb);
+
 	ireq = inet_rsk(req);
 	ireq->loc_addr = daddr;
 	ireq->rmt_addr = saddr;
@@ -1711,7 +1775,7 @@
 }
 EXPORT_SYMBOL(tcp_v4_syn_recv_sock);
 
-static struct sock *tcp_v4_hnd_req(struct sock *sk, struct sk_buff *skb)
+struct sock *tcp_v4_hnd_req(struct sock *sk, struct sk_buff *skb)
 {
 	struct tcphdr *th = tcp_hdr(skb);
 	const struct iphdr *iph = ip_hdr(skb);
@@ -1728,8 +1792,15 @@
 
 	if (nsk) {
 		if (nsk->sk_state != TCP_TIME_WAIT) {
+			/* Don't lock again the meta-sk. It has been locked
+			 * before mptcp_v4_do_rcv.
+			 */
+			if (tcp_sk(nsk)->mpc && !is_meta_sk(sk))
+				bh_lock_sock(mptcp_meta_sk(nsk));
 			bh_lock_sock(nsk);
+
 			return nsk;
+
 		}
 		inet_twsk_put(inet_twsk(nsk));
 		return NULL;
@@ -1786,6 +1857,9 @@
 		goto discard;
 #endif
 
+	if (is_meta_sk(sk))
+		return mptcp_v4_do_rcv(sk, skb);
+
 	if (sk->sk_state == TCP_ESTABLISHED) { /* Fast path */
 		struct dst_entry *dst = sk->sk_rx_dst;
 
@@ -1920,7 +1994,7 @@
 	} else if (skb_queue_len(&tp->ucopy.prequeue) == 1) {
 		wake_up_interruptible_sync_poll(sk_sleep(sk),
 					   POLLIN | POLLRDNORM | POLLRDBAND);
-		if (!inet_csk_ack_scheduled(sk))
+		if (!inet_csk_ack_scheduled(sk) && !tp->mpc)
 			inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK,
 						  (3 * tcp_rto_min(sk)) / 4,
 						  TCP_RTO_MAX);
@@ -1937,7 +2011,7 @@
 {
 	const struct iphdr *iph;
 	const struct tcphdr *th;
-	struct sock *sk;
+	struct sock *sk, *meta_sk = NULL;
 	int ret;
 	struct net *net = dev_net(skb->dev);
 
@@ -1970,18 +2044,42 @@
 	TCP_SKB_CB(skb)->end_seq = (TCP_SKB_CB(skb)->seq + th->syn + th->fin +
 				    skb->len - th->doff * 4);
 	TCP_SKB_CB(skb)->ack_seq = ntohl(th->ack_seq);
+#ifdef CONFIG_MPTCP
+	TCP_SKB_CB(skb)->mptcp_flags = 0;
+	TCP_SKB_CB(skb)->dss_off = 0;
+#endif
 	TCP_SKB_CB(skb)->when	 = 0;
 	TCP_SKB_CB(skb)->ip_dsfield = ipv4_get_dsfield(iph);
 	TCP_SKB_CB(skb)->sacked	 = 0;
 
 	sk = __inet_lookup_skb(&tcp_hashinfo, skb, th->source, th->dest);
-	if (!sk)
-		goto no_tcp_socket;
 
 process:
-	if (sk->sk_state == TCP_TIME_WAIT)
+	if (sk && sk->sk_state == TCP_TIME_WAIT)
 		goto do_time_wait;
 
+#ifdef CONFIG_MPTCP
+	if (!sk && th->syn && !th->ack) {
+		int ret = mptcp_lookup_join(skb, NULL);
+
+		if (ret < 0) {
+			tcp_v4_send_reset(NULL, skb);
+			goto discard_it;
+		} else if (ret > 0) {
+			return 0;
+		}
+	}
+
+	/* Is there a pending request sock for this segment ? */
+	if ((!sk || sk->sk_state == TCP_LISTEN) && mptcp_check_req(skb, net)) {
+		if (sk)
+			sock_put(sk);
+		return 0;
+	}
+#endif
+	if (!sk)
+		goto no_tcp_socket;
+
 	if (unlikely(iph->ttl < inet_sk(sk)->min_ttl)) {
 		NET_INC_STATS_BH(net, LINUX_MIB_TCPMINTTLDROP);
 		goto discard_and_relse;
@@ -1997,11 +2095,20 @@
 	sk_mark_napi_id(sk, skb);
 	skb->dev = NULL;
 
-	bh_lock_sock_nested(sk);
+	if (tcp_sk(sk)->mpc) {
+		meta_sk = mptcp_meta_sk(sk);
+
+		bh_lock_sock_nested(meta_sk);
+		skb->sk = sk;
+	} else {
+		meta_sk = sk;
+		bh_lock_sock_nested(sk);
+	}
+
 	ret = 0;
-	if (!sock_owned_by_user(sk)) {
+	if (!sock_owned_by_user(meta_sk)) {
 #ifdef CONFIG_NET_DMA
-		struct tcp_sock *tp = tcp_sk(sk);
+		struct tcp_sock *tp = tcp_sk(meta_sk);
 		if (!tp->ucopy.dma_chan && tp->ucopy.pinned_list)
 			tp->ucopy.dma_chan = net_dma_find_channel();
 		if (tp->ucopy.dma_chan)
@@ -2009,16 +2116,16 @@
 		else
 #endif
 		{
-			if (!tcp_prequeue(sk, skb))
+			if (!tcp_prequeue(meta_sk, skb))
 				ret = tcp_v4_do_rcv(sk, skb);
 		}
-	} else if (unlikely(sk_add_backlog(sk, skb,
-					   sk->sk_rcvbuf + sk->sk_sndbuf))) {
-		bh_unlock_sock(sk);
+	} else if (unlikely(sk_add_backlog(meta_sk, skb,
+					   meta_sk->sk_rcvbuf + meta_sk->sk_sndbuf))) {
+		bh_unlock_sock(meta_sk);
 		NET_INC_STATS_BH(net, LINUX_MIB_TCPBACKLOGDROP);
 		goto discard_and_relse;
 	}
-	bh_unlock_sock(sk);
+	bh_unlock_sock(meta_sk);
 
 	sock_put(sk);
 
@@ -2073,6 +2180,18 @@
 			sk = sk2;
 			goto process;
 		}
+#ifdef CONFIG_MPTCP
+		if (th->syn && !th->ack) {
+			int ret = mptcp_lookup_join(skb, inet_twsk(sk));
+
+			if (ret < 0) {
+				tcp_v4_send_reset(NULL, skb);
+				goto discard_it;
+			} else if (ret > 0) {
+				return 0;
+			}
+		}
+#endif
 		/* Fall through to ACK */
 	}
 	case TCP_TW_ACK:
@@ -2155,6 +2274,11 @@
 
 	tcp_cleanup_congestion_control(sk);
 
+	if (tp->mpc)
+		mptcp_destroy_sock(sk);
+	if (tp->inside_tk_table)
+		mptcp_hash_remove(tp);
+
 	/* Cleanup up the write buffer. */
 	tcp_write_queue_purge(sk);
 
diff -Naur a/net/ipv4/tcp_minisocks.c b/net/ipv4/tcp_minisocks.c
--- a/net/ipv4/tcp_minisocks.c	2013-09-02 22:46:10.000000000 +0200
+++ b/net/ipv4/tcp_minisocks.c	2013-10-06 18:26:04.385867543 +0200
@@ -18,11 +18,13 @@
  *		Jorge Cwik, <[e-mail]>
  */
 
+#include <linux/kconfig.h>
 #include <linux/mm.h>
 #include <linux/module.h>
 #include <linux/slab.h>
 #include <linux/sysctl.h>
 #include <linux/workqueue.h>
+#include <net/mptcp.h>
 #include <net/tcp.h>
 #include <net/inet_common.h>
 #include <net/xfrm.h>
@@ -95,10 +97,13 @@
 	struct tcp_options_received tmp_opt;
 	struct tcp_timewait_sock *tcptw = tcp_twsk((struct sock *)tw);
 	bool paws_reject = false;
+	struct mptcp_options_received mopt;
 
 	tmp_opt.saw_tstamp = 0;
 	if (th->doff > (sizeof(*th) >> 2) && tcptw->tw_ts_recent_stamp) {
-		tcp_parse_options(skb, &tmp_opt, 0, NULL);
+		mptcp_init_mp_opt(&mopt);
+
+		tcp_parse_options(skb, &tmp_opt, &mopt, 0, NULL);
 
 		if (tmp_opt.saw_tstamp) {
 			tmp_opt.rcv_tsecr	-= tcptw->tw_ts_offset;
@@ -106,6 +111,11 @@
 			tmp_opt.ts_recent_stamp	= tcptw->tw_ts_recent_stamp;
 			paws_reject = tcp_paws_reject(&tmp_opt, th->rst);
 		}
+
+		if (unlikely(mopt.mp_fclose) && tcptw->mptcp_tw) {
+			if (mopt.mptcp_key == tcptw->mptcp_tw->loc_key)
+				goto kill_with_rst;
+		}
 	}
 
 	if (tw->tw_substate == TCP_FIN_WAIT2) {
@@ -128,6 +138,16 @@
 		if (!th->ack ||
 		    !after(TCP_SKB_CB(skb)->end_seq, tcptw->tw_rcv_nxt) ||
 		    TCP_SKB_CB(skb)->end_seq == TCP_SKB_CB(skb)->seq) {
+			/* If mptcp_is_data_fin() returns true, we are sure that
+			 * mopt has been initialized - otherwise it would not
+			 * be a DATA_FIN.
+			 */
+			if (tcptw->mptcp_tw && tcptw->mptcp_tw->meta_tw &&
+			    mptcp_is_data_fin(skb) &&
+			    TCP_SKB_CB(skb)->seq == tcptw->tw_rcv_nxt &&
+			    mopt.data_seq + 1 == (u32)tcptw->mptcp_tw->rcv_nxt)
+				return TCP_TW_ACK;
+
 			inet_twsk_put(tw);
 			return TCP_TW_SUCCESS;
 		}
@@ -159,6 +179,7 @@
 		else
 			inet_twsk_schedule(tw, &tcp_death_row, TCP_TIMEWAIT_LEN,
 					   TCP_TIMEWAIT_LEN);
+
 		return TCP_TW_ACK;
 	}
 
@@ -270,6 +291,11 @@
 	const struct tcp_sock *tp = tcp_sk(sk);
 	bool recycle_ok = false;
 
+	if (is_meta_sk(sk)) {
+		mptcp_update_tw_socks(tp, state);
+		goto tcp_done;
+	}
+
 	if (tcp_death_row.sysctl_tw_recycle && tp->rx_opt.ts_recent_stamp)
 		recycle_ok = tcp_remember_stamp(sk);
 
@@ -290,6 +316,15 @@
 		tcptw->tw_ts_recent_stamp = tp->rx_opt.ts_recent_stamp;
 		tcptw->tw_ts_offset	= tp->tsoffset;
 
+		if (tp->mpc) {
+			if (mptcp_time_wait(sk, tcptw)) {
+				inet_twsk_free(tw);
+				goto exit;
+			}
+		} else {
+			tcptw->mptcp_tw = NULL;
+		}
+
 #if IS_ENABLED(CONFIG_IPV6)
 		if (tw->tw_family == PF_INET6) {
 			struct ipv6_pinfo *np = inet6_sk(sk);
@@ -349,15 +384,18 @@
 		NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPTIMEWAITOVERFLOW);
 	}
 
+exit:
 	tcp_update_metrics(sk);
+tcp_done:
 	tcp_done(sk);
 }
 
 void tcp_twsk_destructor(struct sock *sk)
 {
-#ifdef CONFIG_TCP_MD5SIG
 	struct tcp_timewait_sock *twsk = tcp_twsk(sk);
-
+	if (twsk->mptcp_tw)
+		mptcp_twsk_destructor(twsk);
+#ifdef CONFIG_TCP_MD5SIG
 	if (twsk->tw_md5_key)
 		kfree_rcu(twsk->tw_md5_key, rcu);
 #endif
@@ -394,6 +432,9 @@
 
 		newtp->snd_sml = newtp->snd_una =
 		newtp->snd_nxt = newtp->snd_up = treq->snt_isn + 1;
+#ifdef CONFIG_MPTCP
+		memset(&newtp->rcvq_space, 0, sizeof(newtp->rcvq_space));
+#endif
 
 		tcp_prequeue_init(newtp);
 		INIT_LIST_HEAD(&newtp->tsq_node);
@@ -468,6 +509,8 @@
 			newtp->rx_opt.ts_recent_stamp = 0;
 			newtp->tcp_header_len = sizeof(struct tcphdr);
 		}
+		if (treq->saw_mpc)
+			newtp->tcp_header_len += MPTCP_SUB_LEN_DSM_ALIGN;
 		newtp->tsoffset = 0;
 #ifdef CONFIG_TCP_MD5SIG
 		newtp->md5sig_info = NULL;	/*XXX*/
@@ -504,16 +547,20 @@
 			   bool fastopen)
 {
 	struct tcp_options_received tmp_opt;
+	struct mptcp_options_received mopt;
 	struct sock *child;
 	const struct tcphdr *th = tcp_hdr(skb);
 	__be32 flg = tcp_flag_word(th) & (TCP_FLAG_RST|TCP_FLAG_SYN|TCP_FLAG_ACK);
 	bool paws_reject = false;
 
-	BUG_ON(fastopen == (sk->sk_state == TCP_LISTEN));
+	BUG_ON(!tcp_sk(sk)->mpc && fastopen == (sk->sk_state == TCP_LISTEN));
 
 	tmp_opt.saw_tstamp = 0;
+
+	mptcp_init_mp_opt(&mopt);
+
 	if (th->doff > (sizeof(struct tcphdr)>>2)) {
-		tcp_parse_options(skb, &tmp_opt, 0, NULL);
+		tcp_parse_options(skb, &tmp_opt, &mopt, 0, NULL);
 
 		if (tmp_opt.saw_tstamp) {
 			tmp_opt.ts_recent = req->ts_recent;
@@ -552,7 +599,14 @@
 		 *
 		 * Reset timer after retransmitting SYNACK, similar to
 		 * the idea of fast retransmit in recovery.
+		 *
+		 * Fall back to TCP if MP_CAPABLE is not set.
 		 */
+
+		if (tcp_rsk(req)->saw_mpc && !mopt.saw_mpc)
+			tcp_rsk(req)->saw_mpc = false;
+
+
 		if (!inet_rtx_syn_ack(sk, req))
 			req->expires = min(TCP_TIMEOUT_INIT << req->num_timeout,
 					   TCP_RTO_MAX) + jiffies;
@@ -680,7 +734,20 @@
 
 	/* While TCP_DEFER_ACCEPT is active, drop bare ACK. */
 	if (req->num_timeout < inet_csk(sk)->icsk_accept_queue.rskq_defer_accept &&
-	    TCP_SKB_CB(skb)->end_seq == tcp_rsk(req)->rcv_isn + 1) {
+	    TCP_SKB_CB(skb)->end_seq == tcp_rsk(req)->rcv_isn + 1 &&
+	    /* TODO MPTCP:
+	     * We do this here, because otherwise options sent in the third ack,
+	     * or duplicate fourth ack will get lost. Options like MP_PRIO, ADD_ADDR,...
+	     *
+	     * We could store them in request_sock, but this would mean that we
+	     * have to put tcp_options_received and mptcp_options_received in there,
+	     * increasing considerably the size of the request-sock.
+	     *
+	     * As soon as we have reworked the request-sock MPTCP-fields and
+	     * created a mptcp_request_sock structure, we can handle options
+	     * correclty there without increasing request_sock.
+	     */
+	    !tcp_rsk(req)->saw_mpc) {
 		inet_rsk(req)->acked = 1;
 		NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPDEFERACCEPTDROP);
 		return NULL;
@@ -692,10 +759,29 @@
 	 * ESTABLISHED STATE. If it will be dropped after
 	 * socket is created, wait for troubles.
 	 */
-	child = inet_csk(sk)->icsk_af_ops->syn_recv_sock(sk, skb, req, NULL);
+#if defined(CONFIG_MPTCP)
+	if (tcp_sk(sk)->mpc)
+		/* MPTCP: We call the mptcp-specific syn_recv_sock */
+		child = tcp_sk(sk)->mpcb->syn_recv_sock(sk, skb, req, NULL);
+	else
+#endif
+		child = inet_csk(sk)->icsk_af_ops->syn_recv_sock(sk, skb,
+				req, NULL);
+
 	if (child == NULL)
 		goto listen_overflow;
 
+	if (!is_meta_sk(sk)) {
+		int ret = mptcp_check_req_master(sk, child, req, prev, &mopt);
+		if (ret < 0)
+			goto listen_overflow;
+
+		/* MPTCP-supported */
+		if (!ret)
+			return tcp_sk(child)->mpcb->master_sk;
+	} else {
+		return mptcp_check_req_child(sk, child, req, prev, &mopt);
+	}
 	inet_csk_reqsk_queue_unlink(sk, req, prev);
 	inet_csk_reqsk_queue_removed(sk, req);
 
@@ -745,8 +831,9 @@
 {
 	int ret = 0;
 	int state = child->sk_state;
+	struct sock *meta_sk = tcp_sk(child)->mpc ? mptcp_meta_sk(child) : child;
 
-	if (!sock_owned_by_user(child)) {
+	if (!sock_owned_by_user(meta_sk)) {
 		ret = tcp_rcv_state_process(child, skb, tcp_hdr(skb),
 					    skb->len);
 		/* Wakeup parent, send SIGIO */
@@ -757,10 +844,14 @@
 		 * in main socket hash table and lock on listening
 		 * socket does not protect us more.
 		 */
-		__sk_add_backlog(child, skb);
+		if (tcp_sk(child)->mpc)
+			skb->sk = child;
+		__sk_add_backlog(meta_sk, skb);
 	}
 
-	bh_unlock_sock(child);
+	if (tcp_sk(child)->mpc)
+		bh_unlock_sock(child);
+	bh_unlock_sock(meta_sk);
 	sock_put(child);
 	return ret;
 }
diff -Naur a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
--- a/net/ipv4/tcp_output.c	2013-09-02 22:46:10.000000000 +0200
+++ b/net/ipv4/tcp_output.c	2013-10-06 18:26:04.389867493 +0200
@@ -36,6 +36,8 @@
 
 #define pr_fmt(fmt) "TCP: " fmt
 
+#include <net/mptcp.h>
+#include <net/ipv6.h>
 #include <net/tcp.h>
 
 #include <linux/compiler.h>
@@ -69,7 +71,7 @@
 			   int push_one, gfp_t gfp);
 
 /* Account for new data that has been sent to the network. */
-static void tcp_event_new_data_sent(struct sock *sk, const struct sk_buff *skb)
+void tcp_event_new_data_sent(struct sock *sk, const struct sk_buff *skb)
 {
 	struct inet_connection_sock *icsk = inet_csk(sk);
 	struct tcp_sock *tp = tcp_sk(sk);
@@ -208,9 +210,14 @@
 void tcp_select_initial_window(int __space, __u32 mss,
 			       __u32 *rcv_wnd, __u32 *window_clamp,
 			       int wscale_ok, __u8 *rcv_wscale,
-			       __u32 init_rcv_wnd)
+			       __u32 init_rcv_wnd, const struct sock *sk)
 {
-	unsigned int space = (__space < 0 ? 0 : __space);
+	unsigned int space;
+
+	if (tcp_sk(sk)->mpc)
+		mptcp_select_initial_window(&__space, window_clamp, sk);
+
+	space = (__space < 0 ? 0 : __space);
 
 	/* If no clamp set the clamp to the max possible scaled window */
 	if (*window_clamp == 0)
@@ -266,7 +273,11 @@
 static u16 tcp_select_window(struct sock *sk)
 {
 	struct tcp_sock *tp = tcp_sk(sk);
-	u32 cur_win = tcp_receive_window(tp);
+	/* The window must never shrink at the meta-level. At the subflow we
+	 * have to allow this. Otherwise we may announce a window too large
+	 * for the current meta-level sk_rcvbuf.
+	 */
+	u32 cur_win = tcp_receive_window(tp->mpc ? tcp_sk(mptcp_meta_sk(sk)) : tp);
 	u32 new_win = __tcp_select_window(sk);
 
 	/* Never shrink the offered window */
@@ -280,6 +291,12 @@
 		 */
 		new_win = ALIGN(cur_win, 1 << tp->rx_opt.rcv_wscale);
 	}
+
+	if (tp->mpc) {
+		mptcp_meta_tp(tp)->rcv_wnd = new_win;
+		mptcp_meta_tp(tp)->rcv_wup = mptcp_meta_tp(tp)->rcv_nxt;
+	}
+
 	tp->rcv_wnd = new_win;
 	tp->rcv_wup = tp->rcv_nxt;
 
@@ -358,7 +375,7 @@
 /* Constructs common control bits of non-data skb. If SYN/FIN is present,
  * auto increment end seqno.
  */
-static void tcp_init_nondata_skb(struct sk_buff *skb, u32 seq, u8 flags)
+void tcp_init_nondata_skb(struct sk_buff *skb, u32 seq, u8 flags)
 {
 	skb->ip_summed = CHECKSUM_PARTIAL;
 	skb->csum = 0;
@@ -376,7 +393,7 @@
 	TCP_SKB_CB(skb)->end_seq = seq;
 }
 
-static inline bool tcp_urg_mode(const struct tcp_sock *tp)
+bool tcp_urg_mode(const struct tcp_sock *tp)
 {
 	return tp->snd_una != tp->snd_up;
 }
@@ -386,17 +403,7 @@
 #define OPTION_MD5		(1 << 2)
 #define OPTION_WSCALE		(1 << 3)
 #define OPTION_FAST_OPEN_COOKIE	(1 << 8)
-
-struct tcp_out_options {
-	u16 options;		/* bit field of OPTION_* */
-	u16 mss;		/* 0 to disable */
-	u8 ws;			/* window scale, 0 to disable */
-	u8 num_sack_blocks;	/* number of SACK blocks to include */
-	u8 hash_size;		/* bytes in hash_location */
-	__u8 *hash_location;	/* temporary pointer, overloaded */
-	__u32 tsval, tsecr;	/* need to include OPTION_TS */
-	struct tcp_fastopen_cookie *fastopen_cookie;	/* Fast open cookie */
-};
+/* Before adding here - take a look at OPTION_MPTCP in include/net/mptcp.h */
 
 /* Write previously computed TCP options to the packet.
  *
@@ -412,7 +419,7 @@
  * (but it may well be that other scenarios fail similarly).
  */
 static void tcp_options_write(__be32 *ptr, struct tcp_sock *tp,
-			      struct tcp_out_options *opts)
+			      struct tcp_out_options *opts, struct sk_buff *skb)
 {
 	u16 options = opts->options;	/* mungable copy */
 
@@ -495,6 +502,9 @@
 		}
 		ptr += (foc->len + 3) >> 2;
 	}
+
+	if (unlikely(OPTION_MPTCP & opts->options))
+		mptcp_options_write(ptr, tp, opts, skb);
 }
 
 /* Compute TCP options for SYN packets. This is not the final
@@ -546,6 +556,8 @@
 		if (unlikely(!(OPTION_TS & opts->options)))
 			remaining -= TCPOLEN_SACKPERM_ALIGNED;
 	}
+	if (tp->request_mptcp || tp->mpc)
+		mptcp_syn_options(sk, opts, &remaining);
 
 	if (fastopen && fastopen->cookie.len >= 0) {
 		u32 need = TCPOLEN_EXP_FASTOPEN_BASE + fastopen->cookie.len;
@@ -619,6 +631,9 @@
 		}
 	}
 
+	if (tcp_rsk(req)->saw_mpc)
+		mptcp_synack_options(req, opts, &remaining);
+
 	return MAX_TCP_OPTION_SPACE - remaining;
 }
 
@@ -650,16 +665,22 @@
 		opts->tsecr = tp->rx_opt.ts_recent;
 		size += TCPOLEN_TSTAMP_ALIGNED;
 	}
+	if (tp->mpc)
+		mptcp_established_options(sk, skb, opts, &size);
 
 	eff_sacks = tp->rx_opt.num_sacks + tp->rx_opt.dsack;
 	if (unlikely(eff_sacks)) {
-		const unsigned int remaining = MAX_TCP_OPTION_SPACE - size;
-		opts->num_sack_blocks =
-			min_t(unsigned int, eff_sacks,
-			      (remaining - TCPOLEN_SACK_BASE_ALIGNED) /
-			      TCPOLEN_SACK_PERBLOCK);
-		size += TCPOLEN_SACK_BASE_ALIGNED +
-			opts->num_sack_blocks * TCPOLEN_SACK_PERBLOCK;
+		const unsigned remaining = MAX_TCP_OPTION_SPACE - size;
+		if (remaining < TCPOLEN_SACK_BASE_ALIGNED)
+			opts->num_sack_blocks = 0;
+		else
+			opts->num_sack_blocks =
+			    min_t(unsigned int, eff_sacks,
+				  (remaining - TCPOLEN_SACK_BASE_ALIGNED) /
+				  TCPOLEN_SACK_PERBLOCK);
+		if (opts->num_sack_blocks)
+			size += TCPOLEN_SACK_BASE_ALIGNED +
+			    opts->num_sack_blocks * TCPOLEN_SACK_PERBLOCK;
 	}
 
 	return size;
@@ -736,6 +757,32 @@
 			  (1UL << TCP_WRITE_TIMER_DEFERRED) |	\
 			  (1UL << TCP_DELACK_TIMER_DEFERRED) |	\
 			  (1UL << TCP_MTU_REDUCED_DEFERRED))
+
+static void mptcp_release_cb(struct sock *meta_sk)
+{
+	struct tcp_sock *meta_tp = tcp_sk(meta_sk);
+	struct sock *sk;
+	unsigned long flags, nflags;
+
+	/* perform an atomic operation only if at least one flag is set */
+	do {
+		flags = meta_tp->tsq_flags;
+		if (!(flags & TCP_DEFERRED_ALL))
+			return;
+		nflags = flags & ~TCP_DEFERRED_ALL;
+	} while (cmpxchg(&meta_tp->tsq_flags, flags, nflags) != flags);
+
+	if (flags & (1UL << TCP_WRITE_TIMER_DEFERRED))
+		__sock_put(meta_sk);
+	if (flags & (1UL << TCP_DELACK_TIMER_DEFERRED))
+		__sock_put(meta_sk);
+	if (flags & (1UL << TCP_MTU_REDUCED_DEFERRED))
+		__sock_put(meta_sk);
+
+	mptcp_for_each_sk(tcp_sk(meta_sk)->mpcb, sk)
+		sk->sk_prot->release_cb(sk);
+}
+
 /**
  * tcp_release_cb - tcp release_sock() callback
  * @sk: socket
@@ -748,6 +795,11 @@
 	struct tcp_sock *tp = tcp_sk(sk);
 	unsigned long flags, nflags;
 
+	if (is_meta_sk(sk)) {
+		mptcp_release_cb(sk);
+		return;
+	}
+
 	/* perform an atomic operation only if at least one flag is set */
 	do {
 		flags = tp->tsq_flags;
@@ -830,8 +882,8 @@
  * We are working here with either a clone of the original
  * SKB, or a fresh unique copy made by the retransmit engine.
  */
-static int tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, int clone_it,
-			    gfp_t gfp_mask)
+int tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, int clone_it,
+		        gfp_t gfp_mask)
 {
 	const struct inet_connection_sock *icsk = inet_csk(sk);
 	struct inet_sock *inet;
@@ -851,6 +903,8 @@
 	if (icsk->icsk_ca_ops->flags & TCP_CONG_RTT_STAMP)
 		__net_timestamp(skb);
 
+	tp = tcp_sk(sk);
+
 	if (likely(clone_it)) {
 		const struct sk_buff *fclone = skb + 1;
 
@@ -859,16 +913,33 @@
 			NET_INC_STATS_BH(sock_net(sk),
 					 LINUX_MIB_TCPSPURIOUS_RTX_HOSTQUEUES);
 
-		if (unlikely(skb_cloned(skb)))
-			skb = pskb_copy(skb, gfp_mask);
-		else
+		if (unlikely(skb_cloned(skb))) {
+			struct sk_buff *newskb;
+			if (mptcp_is_data_seq(skb))
+				skb_push(skb, MPTCP_SUB_LEN_DSS_ALIGN +
+					      MPTCP_SUB_LEN_ACK_ALIGN +
+					      MPTCP_SUB_LEN_SEQ_ALIGN);
+
+			newskb = pskb_copy(skb, gfp_mask);
+
+			if (mptcp_is_data_seq(skb)) {
+				skb_pull(skb, MPTCP_SUB_LEN_DSS_ALIGN +
+					      MPTCP_SUB_LEN_ACK_ALIGN +
+					      MPTCP_SUB_LEN_SEQ_ALIGN);
+				if (newskb)
+					skb_pull(newskb, MPTCP_SUB_LEN_DSS_ALIGN +
+							 MPTCP_SUB_LEN_ACK_ALIGN +
+							 MPTCP_SUB_LEN_SEQ_ALIGN);
+			}
+			skb = newskb;
+		} else {
 			skb = skb_clone(skb, gfp_mask);
+		}
 		if (unlikely(!skb))
 			return -ENOBUFS;
 	}
 
 	inet = inet_sk(sk);
-	tp = tcp_sk(sk);
 	tcb = TCP_SKB_CB(skb);
 	memset(&opts, 0, sizeof(opts));
 
@@ -927,7 +998,7 @@
 		}
 	}
 
-	tcp_options_write((__be32 *)(th + 1), tp, &opts);
+	tcp_options_write((__be32 *)(th + 1), tp, &opts, skb);
 	if (likely((tcb->tcp_flags & TCPHDR_SYN) == 0))
 		TCP_ECN_send(sk, skb, tcp_header_size);
 
@@ -966,7 +1037,7 @@
  * NOTE: probe0 timer is not checked, do not forget tcp_push_pending_frames,
  * otherwise socket can stall.
  */
-static void tcp_queue_skb(struct sock *sk, struct sk_buff *skb)
+void tcp_queue_skb(struct sock *sk, struct sk_buff *skb)
 {
 	struct tcp_sock *tp = tcp_sk(sk);
 
@@ -979,11 +1050,11 @@
 }
 
 /* Initialize TSO segments for a packet. */
-static void tcp_set_skb_tso_segs(const struct sock *sk, struct sk_buff *skb,
-				 unsigned int mss_now)
+void tcp_set_skb_tso_segs(const struct sock *sk, struct sk_buff *skb,
+			  unsigned int mss_now)
 {
-	if (skb->len <= mss_now || !sk_can_gso(sk) ||
-	    skb->ip_summed == CHECKSUM_NONE) {
+	if (skb->len <= mss_now || (is_meta_sk(sk) && !mptcp_sk_can_gso(sk)) ||
+	    (!is_meta_sk(sk) && !sk_can_gso(sk)) || skb->ip_summed == CHECKSUM_NONE) {
 		/* Avoid the costly divide in the normal
 		 * non-TSO case.
 		 */
@@ -1015,7 +1086,7 @@
 /* Pcount in the middle of the write queue got changed, we need to do various
  * tweaks to fix counters
  */
-static void tcp_adjust_pcount(struct sock *sk, const struct sk_buff *skb, int decr)
+void tcp_adjust_pcount(struct sock *sk, const struct sk_buff *skb, int decr)
 {
 	struct tcp_sock *tp = tcp_sk(sk);
 
@@ -1056,6 +1127,9 @@
 	int nlen;
 	u8 flags;
 
+	if (tcp_sk(sk)->mpc && mptcp_is_data_seq(skb))
+		mptcp_fragment(sk, skb, len, mss_now, 0);
+
 	if (WARN_ON(len > skb->len))
 		return -EINVAL;
 
@@ -1140,7 +1214,7 @@
  * eventually). The difference is that pulled data not copied, but
  * immediately discarded.
  */
-static void __pskb_trim_head(struct sk_buff *skb, int len)
+void __pskb_trim_head(struct sk_buff *skb, int len)
 {
 	int i, k, eat;
 
@@ -1179,6 +1253,9 @@
 /* Remove acked data from a packet in the transmit queue. */
 int tcp_trim_head(struct sock *sk, struct sk_buff *skb, u32 len)
 {
+	if (tcp_sk(sk)->mpc && !is_meta_sk(sk) && mptcp_is_data_seq(skb))
+		return mptcp_trim_head(sk, skb, len);
+
 	if (skb_unclone(skb, GFP_ATOMIC))
 		return -ENOMEM;
 
@@ -1196,6 +1273,15 @@
 	if (tcp_skb_pcount(skb) > 1)
 		tcp_set_skb_tso_segs(sk, skb, tcp_skb_mss(skb));
 
+#ifdef CONFIG_MPTCP
+	/* Some data got acked - we assume that the seq-number reached the dest.
+	 * Anyway, our MPTCP-option has been trimmed above - we lost it here.
+	 * Only remove the SEQ if the call does not come from a meta retransmit.
+	 */
+	if (tcp_sk(sk)->mpc && !is_meta_sk(sk))
+		TCP_SKB_CB(skb)->mptcp_flags &= ~MPTCPHDR_SEQ;
+#endif
+
 	return 0;
 }
 
@@ -1355,7 +1441,7 @@
 }
 
 /* Congestion window validation. (RFC2861) */
-static void tcp_cwnd_validate(struct sock *sk)
+void tcp_cwnd_validate(struct sock *sk)
 {
 	struct tcp_sock *tp = tcp_sk(sk);
 
@@ -1386,16 +1472,25 @@
  * modulo only when the receiver window alone is the limiting factor or
  * when we would be allowed to send the split-due-to-Nagle skb fully.
  */
-static unsigned int tcp_mss_split_point(const struct sock *sk, const struct sk_buff *skb,
-					unsigned int mss_now, unsigned int max_segs)
+unsigned int tcp_mss_split_point(const struct sock *sk, const struct sk_buff *skb,
+				 unsigned int mss_now, unsigned int max_segs)
 {
 	const struct tcp_sock *tp = tcp_sk(sk);
+	const struct sock *meta_sk = tp->mpc ? mptcp_meta_sk(sk) : sk;
 	u32 needed, window, max_len;
 
-	window = tcp_wnd_end(tp) - TCP_SKB_CB(skb)->seq;
+	if (!tp->mpc)
+		window = tcp_wnd_end(tp) - TCP_SKB_CB(skb)->seq;
+	else
+		/* We need to evaluate the available space in the sending window
+		 * at the subflow level. However, the subflow seq has not yet
+		 * been set. Nevertheless we know that the caller will set it to
+		 * write_seq.
+		 */
+		window = tcp_wnd_end(tp) - tp->write_seq;
 	max_len = mss_now * max_segs;
 
-	if (likely(max_len <= window && skb != tcp_write_queue_tail(sk)))
+	if (likely(max_len <= window && skb != tcp_write_queue_tail(meta_sk)))
 		return max_len;
 
 	needed = min(skb->len, window);
@@ -1409,13 +1504,14 @@
 /* Can at least one segment of SKB be sent right now, according to the
  * congestion window rules?  If so, return how many segments are allowed.
  */
-static inline unsigned int tcp_cwnd_test(const struct tcp_sock *tp,
-					 const struct sk_buff *skb)
+unsigned int tcp_cwnd_test(const struct tcp_sock *tp,
+			   const struct sk_buff *skb)
 {
 	u32 in_flight, cwnd;
 
 	/* Don't be strict about the congestion window for the final FIN.  */
-	if ((TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN) &&
+	if (skb &&
+	    ((TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN) || mptcp_is_data_fin(skb)) &&
 	    tcp_skb_pcount(skb) == 1)
 		return 1;
 
@@ -1431,8 +1527,8 @@
  * This must be invoked the first time we consider transmitting
  * SKB onto the wire.
  */
-static int tcp_init_tso_segs(const struct sock *sk, struct sk_buff *skb,
-			     unsigned int mss_now)
+int tcp_init_tso_segs(const struct sock *sk, struct sk_buff *skb,
+		      unsigned int mss_now)
 {
 	int tso_segs = tcp_skb_pcount(skb);
 
@@ -1469,8 +1565,8 @@
 /* Return true if the Nagle test allows this packet to be
  * sent now.
  */
-static inline bool tcp_nagle_test(const struct tcp_sock *tp, const struct sk_buff *skb,
-				  unsigned int cur_mss, int nonagle)
+bool tcp_nagle_test(const struct tcp_sock *tp, const struct sk_buff *skb,
+		    unsigned int cur_mss, int nonagle)
 {
 	/* Nagle rule does not apply to frames, which sit in the middle of the
 	 * write_queue (they have no chances to get new data).
@@ -1482,7 +1578,8 @@
 		return true;
 
 	/* Don't use the nagle rule for urgent data (or for the final FIN). */
-	if (tcp_urg_mode(tp) || (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN))
+	if (tcp_urg_mode(tp) || (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN) ||
+	    mptcp_is_data_fin(skb))
 		return true;
 
 	if (!tcp_nagle_check(tp, skb, cur_mss, nonagle))
@@ -1492,9 +1589,8 @@
 }
 
 /* Does at least the first segment of SKB fit into the send window? */
-static bool tcp_snd_wnd_test(const struct tcp_sock *tp,
-			     const struct sk_buff *skb,
-			     unsigned int cur_mss)
+bool tcp_snd_wnd_test(const struct tcp_sock *tp, const struct sk_buff *skb,
+		      unsigned int cur_mss)
 {
 	u32 end_seq = TCP_SKB_CB(skb)->end_seq;
 
@@ -1552,6 +1648,9 @@
 	int nlen = skb->len - len;
 	u8 flags;
 
+	if (tcp_sk(sk)->mpc && mptcp_is_data_seq(skb))
+		mptso_fragment(sk, skb, len, mss_now, gfp, 0);
+
 	/* All of a TSO frame must be composed of paged data.  */
 	if (skb->len != skb->data_len)
 		return tcp_fragment(sk, skb, len, mss_now);
@@ -1597,29 +1696,39 @@
  *
  * This algorithm is from John Heffner.
  */
-static bool tcp_tso_should_defer(struct sock *sk, struct sk_buff *skb)
+bool tcp_tso_should_defer(struct sock *sk, struct sk_buff *skb)
 {
 	struct tcp_sock *tp = tcp_sk(sk);
+	struct sock *meta_sk = tp->mpc ? mptcp_meta_sk(sk) : sk;
+	struct tcp_sock *meta_tp = tcp_sk(meta_sk);
 	const struct inet_connection_sock *icsk = inet_csk(sk);
 	u32 send_win, cong_win, limit, in_flight;
 	int win_divisor;
 
-	if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN)
+	if ((TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN) || mptcp_is_data_fin(skb))
 		goto send_now;
 
 	if (icsk->icsk_ca_state != TCP_CA_Open)
 		goto send_now;
 
 	/* Defer for less than two clock ticks. */
-	if (tp->tso_deferred &&
-	    (((u32)jiffies << 1) >> 1) - (tp->tso_deferred >> 1) > 1)
+	if (meta_tp->tso_deferred &&
+	    (((u32)jiffies << 1) >> 1) - (meta_tp->tso_deferred >> 1) > 1)
 		goto send_now;
 
 	in_flight = tcp_packets_in_flight(tp);
 
 	BUG_ON(tcp_skb_pcount(skb) <= 1 || (tp->snd_cwnd <= in_flight));
 
-	send_win = tcp_wnd_end(tp) - TCP_SKB_CB(skb)->seq;
+	if (!tp->mpc)
+		send_win = tcp_wnd_end(tp) - TCP_SKB_CB(skb)->seq;
+	else
+		/* We need to evaluate the available space in the sending window
+		 * at the subflow level. However, the subflow seq has not yet
+		 * been set. Nevertheless we know that the caller will set it to
+		 * write_seq.
+		 */
+		send_win = tcp_wnd_end(tp) - tp->write_seq;
 
 	/* From in_flight test above, we know that cwnd > in_flight.  */
 	cong_win = (tp->snd_cwnd - in_flight) * tp->mss_cache;
@@ -1632,7 +1741,7 @@
 		goto send_now;
 
 	/* Middle in queue won't get any more data, full sendable already? */
-	if ((skb != tcp_write_queue_tail(sk)) && (limit >= skb->len))
+	if ((skb != tcp_write_queue_tail(meta_sk)) && (limit >= skb->len))
 		goto send_now;
 
 	win_divisor = ACCESS_ONCE(sysctl_tcp_tso_win_divisor);
@@ -1658,13 +1767,13 @@
 	/* Ok, it looks like it is advisable to defer.
 	 * Do not rearm the timer if already set to not break TCP ACK clocking.
 	 */
-	if (!tp->tso_deferred)
-		tp->tso_deferred = 1 | (jiffies << 1);
+	if (!meta_tp->tso_deferred)
+		meta_tp->tso_deferred = 1 | (jiffies << 1);
 
 	return true;
 
 send_now:
-	tp->tso_deferred = 0;
+	meta_tp->tso_deferred = 0;
 	return false;
 }
 
@@ -1677,7 +1786,7 @@
  *         1 if a probe was sent,
  *         -1 otherwise
  */
-static int tcp_mtu_probe(struct sock *sk)
+int tcp_mtu_probe(struct sock *sk)
 {
 	struct tcp_sock *tp = tcp_sk(sk);
 	struct inet_connection_sock *icsk = inet_csk(sk);
@@ -1822,6 +1931,9 @@
 	int cwnd_quota;
 	int result;
 
+	if (is_meta_sk(sk))
+		return mptcp_write_xmit(sk, mss_now, nonagle, push_one, gfp);
+
 	sent_pkts = 0;
 
 	if (!push_one) {
@@ -2128,6 +2240,9 @@
 	int full_space = min_t(int, tp->window_clamp, tcp_full_space(sk));
 	int window;
 
+	if (tp->mpc)
+		return __mptcp_select_window(sk);
+
 	if (mss > full_space)
 		mss = full_space;
 
@@ -2258,6 +2373,10 @@
 	if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN)
 		return;
 
+	/* Currently not supported for MPTCP - but it should be possible */
+	if (tp->mpc)
+		return;
+
 	tcp_for_write_queue_from_safe(skb, tmp, sk) {
 		if (!tcp_can_collapse(sk, skb))
 			break;
@@ -2367,8 +2486,24 @@
 	 */
 	if (unlikely((NET_IP_ALIGN && ((unsigned long)skb->data & 3)) ||
 		     skb_headroom(skb) >= 0xFFFF)) {
-		struct sk_buff *nskb = __pskb_copy(skb, MAX_TCP_HEADER,
-						   GFP_ATOMIC);
+		struct sk_buff *nskb;
+
+		if (mptcp_is_data_seq(skb))
+			skb_push(skb, MPTCP_SUB_LEN_DSS_ALIGN +
+				      MPTCP_SUB_LEN_ACK_ALIGN +
+				      MPTCP_SUB_LEN_SEQ_ALIGN);
+
+		nskb = __pskb_copy(skb, MAX_TCP_HEADER, GFP_ATOMIC);
+
+		if (mptcp_is_data_seq(skb)) {
+			skb_pull(skb, MPTCP_SUB_LEN_DSS_ALIGN +
+				      MPTCP_SUB_LEN_ACK_ALIGN +
+				      MPTCP_SUB_LEN_SEQ_ALIGN);
+			if (nskb)
+				skb_pull(nskb, MPTCP_SUB_LEN_DSS_ALIGN +
+					       MPTCP_SUB_LEN_ACK_ALIGN +
+					       MPTCP_SUB_LEN_SEQ_ALIGN);
+		}
 		return nskb ? tcp_transmit_skb(sk, nskb, 0, GFP_ATOMIC) :
 			      -ENOBUFS;
 	} else {
@@ -2593,6 +2728,11 @@
 {
 	struct sk_buff *skb;
 
+	if (is_meta_sk(sk)) {
+		mptcp_send_active_reset(sk, priority);
+		return;
+	}
+
 	/* NOTE: No TCP options attached and we never retransmit this. */
 	skb = alloc_skb(MAX_TCP_HEADER, priority);
 	if (!skb) {
@@ -2695,14 +2835,14 @@
 		    (req->window_clamp > tcp_full_space(sk) || req->window_clamp == 0))
 			req->window_clamp = tcp_full_space(sk);
 
-		/* tcp_full_space because it is guaranteed to be the first packet */
 		tcp_select_initial_window(tcp_full_space(sk),
-			mss - (ireq->tstamp_ok ? TCPOLEN_TSTAMP_ALIGNED : 0),
+			mss - (ireq->tstamp_ok ? TCPOLEN_TSTAMP_ALIGNED : 0) -
+			(tcp_rsk(req)->saw_mpc ? MPTCP_SUB_LEN_DSM_ALIGN : 0),
 			&req->rcv_wnd,
 			&req->window_clamp,
 			ireq->wscale_ok,
 			&rcv_wscale,
-			dst_metric(dst, RTAX_INITRWND));
+			dst_metric(dst, RTAX_INITRWND), sk);
 		ireq->rcv_wscale = rcv_wscale;
 	}
 
@@ -2738,7 +2878,7 @@
 
 	/* RFC1323: The window in SYN & SYN/ACK segments is never scaled. */
 	th->window = htons(min(req->rcv_wnd, 65535U));
-	tcp_options_write((__be32 *)(th + 1), tp, &opts);
+	tcp_options_write((__be32 *)(th + 1), tp, &opts, skb);
 	th->doff = (tcp_header_size >> 2);
 	TCP_ADD_STATS(sock_net(sk), TCP_MIB_OUTSEGS, tcp_skb_pcount(skb));
 
@@ -2798,7 +2938,7 @@
 				  &tp->window_clamp,
 				  sysctl_tcp_window_scaling,
 				  &rcv_wscale,
-				  dst_metric(dst, RTAX_INITRWND));
+				  dst_metric(dst, RTAX_INITRWND), sk);
 
 	tp->rx_opt.rcv_wscale = rcv_wscale;
 	tp->rcv_ssthresh = tp->rcv_wnd;
@@ -2822,6 +2962,18 @@
 	inet_csk(sk)->icsk_rto = TCP_TIMEOUT_INIT;
 	inet_csk(sk)->icsk_retransmits = 0;
 	tcp_clear_retrans(tp);
+
+#ifdef CONFIG_MPTCP
+	if (mptcp_doit(sk)) {
+		if (is_master_tp(tp)) {
+			tp->request_mptcp = 1;
+			mptcp_connect_init(sk);
+		} else {
+			tp->mptcp->snt_isn = tp->write_seq;
+			tp->mptcp->init_rcv_wnd = tp->rcv_wnd;
+		}
+	}
+#endif
 }
 
 static void tcp_connect_queue_skb(struct sock *sk, struct sk_buff *skb)
@@ -3044,6 +3196,13 @@
 	 */
 	buff = alloc_skb(MAX_TCP_HEADER, sk_gfp_atomic(sk, GFP_ATOMIC));
 	if (buff == NULL) {
+
+		/* MPTCP: We don't send a delayed ack if we are sending an mptcp
+		 * ADD_ADDR ack to avoid sending multiple ADD_ADDR acks for the
+		 * same address. */
+		if (tcp_sk(sk)->mptcp_add_addr_ack == 1)
+			return;
+
 		inet_csk_schedule_ack(sk);
 		inet_csk(sk)->icsk_ack.ato = TCP_ATO_MIN;
 		inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK,
@@ -3071,7 +3230,7 @@
  * one is with SEG.SEQ=SND.UNA to deliver urgent pointer, another is
  * out-of-date with SND.UNA-1 to probe window.
  */
-static int tcp_xmit_probe_skb(struct sock *sk, int urgent)
+int tcp_xmit_probe_skb(struct sock *sk, int urgent)
 {
 	struct tcp_sock *tp = tcp_sk(sk);
 	struct sk_buff *skb;
@@ -3110,6 +3269,9 @@
 	if (sk->sk_state == TCP_CLOSE)
 		return -1;
 
+	if (is_meta_sk(sk))
+		return mptcp_write_wakeup(sk);
+
 	if ((skb = tcp_send_head(sk)) != NULL &&
 	    before(TCP_SKB_CB(skb)->seq, tcp_wnd_end(tp))) {
 		int err;
diff -Naur a/net/ipv4/tcp_timer.c b/net/ipv4/tcp_timer.c
--- a/net/ipv4/tcp_timer.c	2013-09-02 22:46:10.000000000 +0200
+++ b/net/ipv4/tcp_timer.c	2013-10-06 18:26:04.391867467 +0200
@@ -20,6 +20,7 @@
 
 #include <linux/module.h>
 #include <linux/gfp.h>
+#include <net/mptcp.h>
 #include <net/tcp.h>
 
 int sysctl_tcp_syn_retries __read_mostly = TCP_SYN_RETRIES;
@@ -32,7 +33,7 @@
 int sysctl_tcp_orphan_retries __read_mostly;
 int sysctl_tcp_thin_linear_timeouts __read_mostly;
 
-static void tcp_write_err(struct sock *sk)
+void tcp_write_err(struct sock *sk)
 {
 	sk->sk_err = sk->sk_err_soft ? : ETIMEDOUT;
 	sk->sk_error_report(sk);
@@ -124,10 +125,8 @@
  * retransmissions with an initial RTO of TCP_RTO_MIN or TCP_TIMEOUT_INIT if
  * syn_set flag is set.
  */
-static bool retransmits_timed_out(struct sock *sk,
-				  unsigned int boundary,
-				  unsigned int timeout,
-				  bool syn_set)
+bool retransmits_timed_out(struct sock *sk, unsigned int boundary,
+			   unsigned int timeout, bool syn_set)
 {
 	unsigned int linear_backoff_thresh, start_ts;
 	unsigned int rto_base = syn_set ? TCP_TIMEOUT_INIT : TCP_RTO_MIN;
@@ -153,7 +152,7 @@
 }
 
 /* A write timeout has occurred. Process the after effects. */
-static int tcp_write_timeout(struct sock *sk)
+int tcp_write_timeout(struct sock *sk)
 {
 	struct inet_connection_sock *icsk = inet_csk(sk);
 	int retry_until;
@@ -164,6 +163,10 @@
 			dst_negative_advice(sk);
 		retry_until = icsk->icsk_syn_retries ? : sysctl_tcp_syn_retries;
 		syn_set = true;
+		/* Stop retransmitting MP_CAPABLE options in SYN if timed out. */
+		if (tcp_sk(sk)->request_mptcp &&
+		    icsk->icsk_retransmits >= mptcp_sysctl_syn_retries())
+			tcp_sk(sk)->request_mptcp = 0;
 	} else {
 		if (retransmits_timed_out(sk, sysctl_tcp_retries1, 0, 0)) {
 			/* Black hole detection */
@@ -244,18 +247,22 @@
 static void tcp_delack_timer(unsigned long data)
 {
 	struct sock *sk = (struct sock *)data;
+	struct sock *meta_sk = tcp_sk(sk)->mpc ? mptcp_meta_sk(sk) : sk;
 
-	bh_lock_sock(sk);
-	if (!sock_owned_by_user(sk)) {
+	bh_lock_sock(meta_sk);
+	if (!sock_owned_by_user(meta_sk)) {
 		tcp_delack_timer_handler(sk);
 	} else {
 		inet_csk(sk)->icsk_ack.blocked = 1;
-		NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_DELAYEDACKLOCKED);
+		NET_INC_STATS_BH(sock_net(meta_sk), LINUX_MIB_DELAYEDACKLOCKED);
 		/* deleguate our work to tcp_release_cb() */
 		if (!test_and_set_bit(TCP_DELACK_TIMER_DEFERRED, &tcp_sk(sk)->tsq_flags))
 			sock_hold(sk);
+		if (tcp_sk(sk)->mpc &&
+		    !test_and_set_bit(TCP_DELACK_TIMER_DEFERRED, &tcp_sk(meta_sk)->tsq_flags))
+			sock_hold(meta_sk);
 	}
-	bh_unlock_sock(sk);
+	bh_unlock_sock(meta_sk);
 	sock_put(sk);
 }
 
@@ -418,6 +425,9 @@
 
 	tcp_enter_loss(sk, 0);
 
+	if (tp->mpc)
+		mptcp_reinject_data(sk, 1);
+
 	if (tcp_retransmit_skb(sk, tcp_write_queue_head(sk)) > 0) {
 		/* Retransmission failed because of local congestion,
 		 * do not backoff.
@@ -468,6 +478,7 @@
 		/* Use normal (exponential) backoff */
 		icsk->icsk_rto = min(icsk->icsk_rto << 1, TCP_RTO_MAX);
 	}
+	mptcp_set_rto(sk);
 	inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, icsk->icsk_rto, TCP_RTO_MAX);
 	if (retransmits_timed_out(sk, sysctl_tcp_retries1 + 1, 0, 0))
 		__sk_dst_reset(sk);
@@ -499,7 +510,10 @@
 		break;
 	case ICSK_TIME_RETRANS:
 		icsk->icsk_pending = 0;
-		tcp_retransmit_timer(sk);
+		if (is_meta_sk(sk))
+			mptcp_retransmit_timer(sk);
+		else
+			tcp_retransmit_timer(sk);
 		break;
 	case ICSK_TIME_PROBE0:
 		icsk->icsk_pending = 0;
@@ -514,16 +528,20 @@
 static void tcp_write_timer(unsigned long data)
 {
 	struct sock *sk = (struct sock *)data;
+	struct sock *meta_sk = tcp_sk(sk)->mpc ? mptcp_meta_sk(sk) : sk;
 
-	bh_lock_sock(sk);
-	if (!sock_owned_by_user(sk)) {
+	bh_lock_sock(meta_sk);
+	if (!sock_owned_by_user(meta_sk)) {
 		tcp_write_timer_handler(sk);
 	} else {
 		/* deleguate our work to tcp_release_cb() */
 		if (!test_and_set_bit(TCP_WRITE_TIMER_DEFERRED, &tcp_sk(sk)->tsq_flags))
 			sock_hold(sk);
+		if (tcp_sk(sk)->mpc &&
+		    !test_and_set_bit(TCP_WRITE_TIMER_DEFERRED, &tcp_sk(meta_sk)->tsq_flags))
+			sock_hold(meta_sk);
 	}
-	bh_unlock_sock(sk);
+	bh_unlock_sock(meta_sk);
 	sock_put(sk);
 }
 
@@ -548,6 +566,11 @@
 	if ((1 << sk->sk_state) & (TCPF_CLOSE | TCPF_LISTEN))
 		return;
 
+	if (is_meta_sk(sk)) {
+		mptcp_set_keepalive(sk, val);
+		return;
+	}
+
 	if (val && !sock_flag(sk, SOCK_KEEPOPEN))
 		inet_csk_reset_keepalive_timer(sk, keepalive_time_when(tcp_sk(sk)));
 	else if (!val)
@@ -560,21 +583,17 @@
 	struct sock *sk = (struct sock *) data;
 	struct inet_connection_sock *icsk = inet_csk(sk);
 	struct tcp_sock *tp = tcp_sk(sk);
+	struct sock *meta_sk = tp->mpc ? mptcp_meta_sk(sk) : sk;
 	u32 elapsed;
 
 	/* Only process if socket is not in use. */
-	bh_lock_sock(sk);
-	if (sock_owned_by_user(sk)) {
+	bh_lock_sock(meta_sk);
+	if (sock_owned_by_user(meta_sk)) {
 		/* Try again later. */
 		inet_csk_reset_keepalive_timer (sk, HZ/20);
 		goto out;
 	}
 
-	if (sk->sk_state == TCP_LISTEN) {
-		tcp_synack_timer(sk);
-		goto out;
-	}
-
 	if (sk->sk_state == TCP_FIN_WAIT2 && sock_flag(sk, SOCK_DEAD)) {
 		if (tp->linger2 >= 0) {
 			const int tmo = tcp_fin_time(sk) - TCP_TIMEWAIT_LEN;
@@ -588,7 +607,13 @@
 		goto death;
 	}
 
-	if (!sock_flag(sk, SOCK_KEEPOPEN) || sk->sk_state == TCP_CLOSE)
+	if (sk->sk_state == TCP_LISTEN || is_meta_sk(sk)) {
+		tcp_synack_timer(sk);
+		goto out;
+	}
+
+	/* MPTCP: Keepalive timers are handled at the subflow level */
+	if (!sock_flag(sk, SOCK_KEEPOPEN) || sk->sk_state == TCP_CLOSE || is_meta_sk(sk))
 		goto out;
 
 	elapsed = keepalive_time_when(tp);
@@ -636,7 +661,7 @@
 	tcp_done(sk);
 
 out:
-	bh_unlock_sock(sk);
+	bh_unlock_sock(meta_sk);
 	sock_put(sk);
 }
 
diff -Naur a/net/ipv6/af_inet6.c b/net/ipv6/af_inet6.c
--- a/net/ipv6/af_inet6.c	2013-09-02 22:46:10.000000000 +0200
+++ b/net/ipv6/af_inet6.c	2013-10-06 18:26:04.397867392 +0200
@@ -96,8 +96,7 @@
 	return (struct ipv6_pinfo *)(((u8 *)sk) + offset);
 }
 
-static int inet6_create(struct net *net, struct socket *sock, int protocol,
-			int kern)
+int inet6_create(struct net *net, struct socket *sock, int protocol, int kern)
 {
 	struct inet_sock *inet;
 	struct ipv6_pinfo *np;
diff -Naur a/net/ipv6/inet6_connection_sock.c b/net/ipv6/inet6_connection_sock.c
--- a/net/ipv6/inet6_connection_sock.c	2013-09-02 22:46:10.000000000 +0200
+++ b/net/ipv6/inet6_connection_sock.c	2013-10-06 18:26:04.405867291 +0200
@@ -96,8 +96,8 @@
 /*
  * request_sock (formerly open request) hash tables.
  */
-static u32 inet6_synq_hash(const struct in6_addr *raddr, const __be16 rport,
-			   const u32 rnd, const u32 synq_hsize)
+u32 inet6_synq_hash(const struct in6_addr *raddr, const __be16 rport,
+		    const u32 rnd, const u32 synq_hsize)
 {
 	u32 c;
 
diff -Naur a/net/ipv6/syncookies.c b/net/ipv6/syncookies.c
--- a/net/ipv6/syncookies.c	2013-09-02 22:46:10.000000000 +0200
+++ b/net/ipv6/syncookies.c	2013-10-06 18:26:04.409867241 +0200
@@ -176,7 +176,7 @@
 
 	/* check for timestamp cookie support */
 	memset(&tcp_opt, 0, sizeof(tcp_opt));
-	tcp_parse_options(skb, &tcp_opt, 0, NULL);
+	tcp_parse_options(skb, &tcp_opt, NULL, 0, NULL);
 
 	if (!cookie_check_timestamp(&tcp_opt, sock_net(sk), &ecn_ok))
 		goto out;
@@ -252,7 +252,7 @@
 	tcp_select_initial_window(tcp_full_space(sk), req->mss,
 				  &req->rcv_wnd, &req->window_clamp,
 				  ireq->wscale_ok, &rcv_wscale,
-				  dst_metric(dst, RTAX_INITRWND));
+				  dst_metric(dst, RTAX_INITRWND), sk);
 
 	ireq->rcv_wscale = rcv_wscale;
 
diff -Naur a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
--- a/net/ipv6/tcp_ipv6.c	2013-09-02 22:46:10.000000000 +0200
+++ b/net/ipv6/tcp_ipv6.c	2013-10-06 18:26:04.420867103 +0200
@@ -64,6 +64,9 @@
 #include <net/secure_seq.h>
 #include <net/tcp_memcontrol.h>
 #include <net/busy_poll.h>
+#include <net/mptcp.h>
+#include <net/mptcp_v6.h>
+
 
 #include <asm/uaccess.h>
 
@@ -73,14 +76,6 @@
 #include <linux/crypto.h>
 #include <linux/scatterlist.h>
 
-static void	tcp_v6_send_reset(struct sock *sk, struct sk_buff *skb);
-static void	tcp_v6_reqsk_send_ack(struct sock *sk, struct sk_buff *skb,
-				      struct request_sock *req);
-
-static int	tcp_v6_do_rcv(struct sock *sk, struct sk_buff *skb);
-
-static const struct inet_connection_sock_af_ops ipv6_mapped;
-static const struct inet_connection_sock_af_ops ipv6_specific;
 #ifdef CONFIG_TCP_MD5SIG
 static const struct tcp_sock_af_ops tcp_sock_ipv6_specific;
 static const struct tcp_sock_af_ops tcp_sock_ipv6_mapped_specific;
@@ -92,7 +87,7 @@
 }
 #endif
 
-static void inet6_sk_rx_dst_set(struct sock *sk, const struct sk_buff *skb)
+void inet6_sk_rx_dst_set(struct sock *sk, const struct sk_buff *skb)
 {
 	struct dst_entry *dst = skb_dst(skb);
 	const struct rt6_info *rt = (const struct rt6_info *)dst;
@@ -104,7 +99,7 @@
 		inet6_sk(sk)->rx_dst_cookie = rt->rt6i_node->fn_sernum;
 }
 
-static void tcp_v6_hash(struct sock *sk)
+void tcp_v6_hash(struct sock *sk)
 {
 	if (sk->sk_state != TCP_CLOSE) {
 		if (inet_csk(sk)->icsk_af_ops == &ipv6_mapped) {
@@ -117,7 +112,7 @@
 	}
 }
 
-static __u32 tcp_v6_init_sequence(const struct sk_buff *skb)
+__u32 tcp_v6_init_sequence(const struct sk_buff *skb)
 {
 	return secure_tcpv6_sequence_number(ipv6_hdr(skb)->daddr.s6_addr32,
 					    ipv6_hdr(skb)->saddr.s6_addr32,
@@ -125,7 +120,7 @@
 					    tcp_hdr(skb)->source);
 }
 
-static int tcp_v6_connect(struct sock *sk, struct sockaddr *uaddr,
+int tcp_v6_connect(struct sock *sk, struct sockaddr *uaddr,
 			  int addr_len)
 {
 	struct sockaddr_in6 *usin = (struct sockaddr_in6 *) uaddr;
@@ -340,7 +335,7 @@
 	const struct ipv6hdr *hdr = (const struct ipv6hdr*)skb->data;
 	const struct tcphdr *th = (struct tcphdr *)(skb->data+offset);
 	struct ipv6_pinfo *np;
-	struct sock *sk;
+	struct sock *sk, *meta_sk;
 	int err;
 	struct tcp_sock *tp;
 	__u32 seq;
@@ -360,8 +355,14 @@
 		return;
 	}
 
-	bh_lock_sock(sk);
-	if (sock_owned_by_user(sk) && type != ICMPV6_PKT_TOOBIG)
+	tp = tcp_sk(sk);
+	if (tp->mpc)
+		meta_sk = mptcp_meta_sk(sk);
+	else
+		meta_sk = sk;
+
+	bh_lock_sock(meta_sk);
+	if (sock_owned_by_user(meta_sk) && type != ICMPV6_PKT_TOOBIG)
 		NET_INC_STATS_BH(net, LINUX_MIB_LOCKDROPPEDICMPS);
 
 	if (sk->sk_state == TCP_CLOSE)
@@ -372,7 +373,6 @@
 		goto out;
 	}
 
-	tp = tcp_sk(sk);
 	seq = ntohl(th->seq);
 	if (sk->sk_state != TCP_LISTEN &&
 	    !between(seq, tp->snd_una, tp->snd_nxt)) {
@@ -399,11 +399,17 @@
 			goto out;
 
 		tp->mtu_info = ntohl(info);
-		if (!sock_owned_by_user(sk))
+		if (!sock_owned_by_user(meta_sk))
 			tcp_v6_mtu_reduced(sk);
-		else if (!test_and_set_bit(TCP_MTU_REDUCED_DEFERRED,
+		else {
+			if (!test_and_set_bit(TCP_MTU_REDUCED_DEFERRED,
 					   &tp->tsq_flags))
-			sock_hold(sk);
+				sock_hold(sk);
+			if (tp->mpc &&
+			    !test_and_set_bit(TCP_MTU_REDUCED_DEFERRED,
+					      &tcp_sk(meta_sk)->tsq_flags))
+				sock_hold(meta_sk);
+		}
 		goto out;
 	}
 
@@ -413,7 +419,7 @@
 	switch (sk->sk_state) {
 		struct request_sock *req, **prev;
 	case TCP_LISTEN:
-		if (sock_owned_by_user(sk))
+		if (sock_owned_by_user(meta_sk))
 			goto out;
 
 		req = inet6_csk_search_req(sk, &prev, th->dest, &hdr->daddr,
@@ -438,7 +444,7 @@
 	case TCP_SYN_SENT:
 	case TCP_SYN_RECV:  /* Cannot happen.
 			       It can, it SYNs are crossed. --ANK */
-		if (!sock_owned_by_user(sk)) {
+		if (!sock_owned_by_user(meta_sk)) {
 			sk->sk_err = err;
 			sk->sk_error_report(sk);		/* Wake people up to see the error (see connect in sock.c) */
 
@@ -448,22 +454,22 @@
 		goto out;
 	}
 
-	if (!sock_owned_by_user(sk) && np->recverr) {
+	if (!sock_owned_by_user(meta_sk) && np->recverr) {
 		sk->sk_err = err;
 		sk->sk_error_report(sk);
 	} else
 		sk->sk_err_soft = err;
 
 out:
-	bh_unlock_sock(sk);
+	bh_unlock_sock(meta_sk);
 	sock_put(sk);
 }
 
 
-static int tcp_v6_send_synack(struct sock *sk, struct dst_entry *dst,
-			      struct flowi6 *fl6,
-			      struct request_sock *req,
-			      u16 queue_mapping)
+int tcp_v6_send_synack(struct sock *sk, struct dst_entry *dst,
+		       struct flowi6 *fl6,
+		       struct request_sock *req,
+		       u16 queue_mapping)
 {
 	struct inet6_request_sock *treq = inet6_rsk(req);
 	struct ipv6_pinfo *np = inet6_sk(sk);
@@ -489,7 +495,7 @@
 	return err;
 }
 
-static int tcp_v6_rtx_synack(struct sock *sk, struct request_sock *req)
+int tcp_v6_rtx_synack(struct sock *sk, struct request_sock *req)
 {
 	struct flowi6 fl6;
 	int res;
@@ -500,7 +506,7 @@
 	return res;
 }
 
-static void tcp_v6_reqsk_destructor(struct request_sock *req)
+void tcp_v6_reqsk_destructor(struct request_sock *req)
 {
 	kfree_skb(inet6_rsk(req)->pktopts);
 }
@@ -719,9 +725,9 @@
 };
 #endif
 
-static void tcp_v6_send_response(struct sk_buff *skb, u32 seq, u32 ack, u32 win,
-				 u32 tsval, u32 tsecr,
-				 struct tcp_md5sig_key *key, int rst, u8 tclass)
+static void tcp_v6_send_response(struct sk_buff *skb, u32 seq, u32 ack,
+				 u32 data_ack, u32 win, u32 tsval, u32 tsecr,
+				 struct tcp_md5sig_key *key, int rst, u8 tclass, int mptcp)
 {
 	const struct tcphdr *th = tcp_hdr(skb);
 	struct tcphdr *t1;
@@ -739,7 +745,10 @@
 	if (key)
 		tot_len += TCPOLEN_MD5SIG_ALIGNED;
 #endif
-
+#ifdef CONFIG_MPTCP
+	if (mptcp)
+		tot_len += MPTCP_SUB_LEN_DSS + MPTCP_SUB_LEN_ACK;
+#endif
 	buff = alloc_skb(MAX_HEADER + sizeof(struct ipv6hdr) + tot_len,
 			 GFP_ATOMIC);
 	if (buff == NULL)
@@ -777,6 +786,17 @@
 		tcp_v6_md5_hash_hdr((__u8 *)topt, key,
 				    &ipv6_hdr(skb)->saddr,
 				    &ipv6_hdr(skb)->daddr, t1);
+		topt += 4;
+	}
+#endif
+#ifdef CONFIG_MPTCP
+	if (mptcp) {
+		/* Construction of 32-bit data_ack */
+		*topt++ = htonl((TCPOPT_MPTCP << 24) |
+				((MPTCP_SUB_LEN_DSS + MPTCP_SUB_LEN_ACK) << 16) |
+				(0x20 << 8) |
+				(0x01));
+		*topt++ = htonl(data_ack);
 	}
 #endif
 
@@ -813,7 +833,7 @@
 	kfree_skb(buff);
 }
 
-static void tcp_v6_send_reset(struct sock *sk, struct sk_buff *skb)
+void tcp_v6_send_reset(struct sock *sk, struct sk_buff *skb)
 {
 	const struct tcphdr *th = tcp_hdr(skb);
 	u32 seq = 0, ack_seq = 0;
@@ -868,7 +888,7 @@
 		ack_seq = ntohl(th->seq) + th->syn + th->fin + skb->len -
 			  (th->doff << 2);
 
-	tcp_v6_send_response(skb, seq, ack_seq, 0, 0, 0, key, 1, 0);
+	tcp_v6_send_response(skb, seq, ack_seq, 0, 0, 0, 0, key, 1, 0, 0);
 
 #ifdef CONFIG_TCP_MD5SIG
 release_sk1:
@@ -879,37 +899,44 @@
 #endif
 }
 
-static void tcp_v6_send_ack(struct sk_buff *skb, u32 seq, u32 ack,
+static void tcp_v6_send_ack(struct sk_buff *skb, u32 seq, u32 ack, u32 data_ack,
 			    u32 win, u32 tsval, u32 tsecr,
-			    struct tcp_md5sig_key *key, u8 tclass)
+			    struct tcp_md5sig_key *key, u8 tclass, int mptcp)
 {
-	tcp_v6_send_response(skb, seq, ack, win, tsval, tsecr, key, 0, tclass);
+	tcp_v6_send_response(skb, seq, ack, data_ack, win, tsval, tsecr, key, 0, tclass, mptcp);
 }
 
 static void tcp_v6_timewait_ack(struct sock *sk, struct sk_buff *skb)
 {
 	struct inet_timewait_sock *tw = inet_twsk(sk);
 	struct tcp_timewait_sock *tcptw = tcp_twsk(sk);
+	u32 data_ack = 0;
+	int mptcp = 0;
 
+	if (tcptw->mptcp_tw && tcptw->mptcp_tw->meta_tw) {
+		data_ack = (u32)tcptw->mptcp_tw->rcv_nxt;
+		mptcp = 1;
+	}
 	tcp_v6_send_ack(skb, tcptw->tw_snd_nxt, tcptw->tw_rcv_nxt,
+			data_ack,
 			tcptw->tw_rcv_wnd >> tw->tw_rcv_wscale,
 			tcp_time_stamp + tcptw->tw_ts_offset,
 			tcptw->tw_ts_recent, tcp_twsk_md5_key(tcptw),
-			tw->tw_tclass);
+			tw->tw_tclass, mptcp);
 
 	inet_twsk_put(tw);
 }
 
-static void tcp_v6_reqsk_send_ack(struct sock *sk, struct sk_buff *skb,
-				  struct request_sock *req)
+void tcp_v6_reqsk_send_ack(struct sock *sk, struct sk_buff *skb,
+			   struct request_sock *req)
 {
 	tcp_v6_send_ack(skb, tcp_rsk(req)->snt_isn + 1, tcp_rsk(req)->rcv_isn + 1,
-			req->rcv_wnd, tcp_time_stamp, req->ts_recent,
-			tcp_v6_md5_do_lookup(sk, &ipv6_hdr(skb)->daddr), 0);
+			0, req->rcv_wnd, tcp_time_stamp, req->ts_recent,
+			tcp_v6_md5_do_lookup(sk, &ipv6_hdr(skb)->daddr), 0, 0);
 }
 
 
-static struct sock *tcp_v6_hnd_req(struct sock *sk,struct sk_buff *skb)
+struct sock *tcp_v6_hnd_req(struct sock *sk,struct sk_buff *skb)
 {
 	struct request_sock *req, **prev;
 	const struct tcphdr *th = tcp_hdr(skb);
@@ -928,7 +955,13 @@
 
 	if (nsk) {
 		if (nsk->sk_state != TCP_TIME_WAIT) {
+			/* Don't lock again the meta-sk. It has been locked
+			 * before mptcp_v6_do_rcv.
+			 */
+			if (tcp_sk(nsk)->mpc && !is_meta_sk(sk))
+				bh_lock_sock(mptcp_meta_sk(nsk));
 			bh_lock_sock(nsk);
+
 			return nsk;
 		}
 		inet_twsk_put(inet_twsk(nsk));
@@ -948,6 +981,7 @@
 static int tcp_v6_conn_request(struct sock *sk, struct sk_buff *skb)
 {
 	struct tcp_options_received tmp_opt;
+	struct mptcp_options_received mopt;
 	struct request_sock *req;
 	struct inet6_request_sock *treq;
 	struct ipv6_pinfo *np = inet6_sk(sk);
@@ -960,6 +994,23 @@
 	if (skb->protocol == htons(ETH_P_IP))
 		return tcp_v4_conn_request(sk, skb);
 
+	tcp_clear_options(&tmp_opt);
+	tmp_opt.mss_clamp = IPV6_MIN_MTU - sizeof(struct tcphdr) - sizeof(struct ipv6hdr);
+	tmp_opt.user_mss = tp->rx_opt.user_mss;
+	mptcp_init_mp_opt(&mopt);
+	tcp_parse_options(skb, &tmp_opt, &mopt, 0, NULL);
+
+#ifdef CONFIG_MPTCP
+	/*MPTCP structures not initialized, so return error */
+	if (mptcp_init_failed)
+		mptcp_init_mp_opt(&mopt);
+
+	if (mopt.is_mp_join)
+		return mptcp_do_join_short(skb, &mopt, &tmp_opt, sock_net(sk));
+	if (mopt.drop_me)
+		goto drop;
+#endif
+
 	if (!ipv6_unicast_destination(skb))
 		goto drop;
 
@@ -974,7 +1025,20 @@
 		goto drop;
 	}
 
-	req = inet6_reqsk_alloc(&tcp6_request_sock_ops);
+#ifdef CONFIG_MPTCP
+	if (mopt.saw_mpc) {
+		req = inet6_reqsk_alloc(&mptcp6_request_sock_ops);
+
+		if (req == NULL)
+			goto drop;
+
+		mptcp_rsk(req)->mpcb = NULL;
+		mptcp_rsk(req)->dss_csum = mopt.dss_csum;
+		mptcp_rsk(req)->collide_tk.pprev = NULL;
+	} else
+#endif
+		req = inet6_reqsk_alloc(&tcp6_request_sock_ops);
+
 	if (req == NULL)
 		goto drop;
 
@@ -982,17 +1046,15 @@
 	tcp_rsk(req)->af_specific = &tcp_request_sock_ipv6_ops;
 #endif
 
-	tcp_clear_options(&tmp_opt);
-	tmp_opt.mss_clamp = IPV6_MIN_MTU - sizeof(struct tcphdr) - sizeof(struct ipv6hdr);
-	tmp_opt.user_mss = tp->rx_opt.user_mss;
-	tcp_parse_options(skb, &tmp_opt, 0, NULL);
-
 	if (want_cookie && !tmp_opt.saw_tstamp)
 		tcp_clear_options(&tmp_opt);
 
 	tmp_opt.tstamp_ok = tmp_opt.saw_tstamp;
 	tcp_openreq_init(req, &tmp_opt, skb);
 
+	if (mopt.saw_mpc)
+		mptcp_reqsk_new_mptcp(req, &tmp_opt, &mopt, skb);
+
 	treq = inet6_rsk(req);
 	treq->rmt_addr = ipv6_hdr(skb)->saddr;
 	treq->loc_addr = ipv6_hdr(skb)->daddr;
@@ -1081,9 +1143,9 @@
 	return 0; /* don't send reset */
 }
 
-static struct sock * tcp_v6_syn_recv_sock(struct sock *sk, struct sk_buff *skb,
-					  struct request_sock *req,
-					  struct dst_entry *dst)
+struct sock *tcp_v6_syn_recv_sock(struct sock *sk, struct sk_buff *skb,
+				  struct request_sock *req,
+				  struct dst_entry *dst)
 {
 	struct inet6_request_sock *treq;
 	struct ipv6_pinfo *newnp, *np = inet6_sk(sk);
@@ -1303,7 +1365,7 @@
  * This is because we cannot sleep with the original spinlock
  * held.
  */
-static int tcp_v6_do_rcv(struct sock *sk, struct sk_buff *skb)
+int tcp_v6_do_rcv(struct sock *sk, struct sk_buff *skb)
 {
 	struct ipv6_pinfo *np = inet6_sk(sk);
 	struct tcp_sock *tp;
@@ -1325,6 +1387,9 @@
 		goto discard;
 #endif
 
+	if (is_meta_sk(sk))
+		return mptcp_v6_do_rcv(sk, skb);
+
 	if (sk_filter(sk, skb))
 		goto discard;
 
@@ -1445,7 +1510,7 @@
 {
 	const struct tcphdr *th;
 	const struct ipv6hdr *hdr;
-	struct sock *sk;
+	struct sock *sk, *meta_sk = NULL;
 	int ret;
 	struct net *net = dev_net(skb->dev);
 
@@ -1476,18 +1541,43 @@
 	TCP_SKB_CB(skb)->end_seq = (TCP_SKB_CB(skb)->seq + th->syn + th->fin +
 				    skb->len - th->doff*4);
 	TCP_SKB_CB(skb)->ack_seq = ntohl(th->ack_seq);
+#ifdef CONFIG_MPTCP
+	TCP_SKB_CB(skb)->mptcp_flags = 0;
+	TCP_SKB_CB(skb)->dss_off = 0;
+#endif
 	TCP_SKB_CB(skb)->when = 0;
 	TCP_SKB_CB(skb)->ip_dsfield = ipv6_get_dsfield(hdr);
 	TCP_SKB_CB(skb)->sacked = 0;
 
 	sk = __inet6_lookup_skb(&tcp_hashinfo, skb, th->source, th->dest);
-	if (!sk)
-		goto no_tcp_socket;
 
 process:
-	if (sk->sk_state == TCP_TIME_WAIT)
+	if (sk && sk->sk_state == TCP_TIME_WAIT)
 		goto do_time_wait;
 
+#ifdef CONFIG_MPTCP
+	if (!sk && th->syn && !th->ack) {
+		int ret = mptcp_lookup_join(skb, NULL);
+
+		if (ret < 0) {
+			tcp_v6_send_reset(NULL, skb);
+			goto discard_it;
+		} else if (ret > 0) {
+			return 0;
+		}
+	}
+
+	/* Is there a pending request sock for this segment ? */
+	if ((!sk || sk->sk_state == TCP_LISTEN) && mptcp_check_req(skb, net)) {
+		if (sk)
+			sock_put(sk);
+		return 0;
+	}
+#endif
+
+	if (!sk)
+		goto no_tcp_socket;
+
 	if (hdr->hop_limit < inet6_sk(sk)->min_hopcount) {
 		NET_INC_STATS_BH(net, LINUX_MIB_TCPMINTTLDROP);
 		goto discard_and_relse;
@@ -1502,11 +1592,20 @@
 	sk_mark_napi_id(sk, skb);
 	skb->dev = NULL;
 
-	bh_lock_sock_nested(sk);
+	if (tcp_sk(sk)->mpc) {
+		meta_sk = mptcp_meta_sk(sk);
+
+		bh_lock_sock_nested(meta_sk);
+		skb->sk = sk;
+	} else {
+		meta_sk = sk;
+		bh_lock_sock_nested(sk);
+	}
+
 	ret = 0;
-	if (!sock_owned_by_user(sk)) {
+	if (!sock_owned_by_user(meta_sk)) {
 #ifdef CONFIG_NET_DMA
-		struct tcp_sock *tp = tcp_sk(sk);
+		struct tcp_sock *tp = tcp_sk(meta_sk);
 		if (!tp->ucopy.dma_chan && tp->ucopy.pinned_list)
 			tp->ucopy.dma_chan = net_dma_find_channel();
 		if (tp->ucopy.dma_chan)
@@ -1514,16 +1613,17 @@
 		else
 #endif
 		{
-			if (!tcp_prequeue(sk, skb))
+			if (!tcp_prequeue(meta_sk, skb))
 				ret = tcp_v6_do_rcv(sk, skb);
 		}
-	} else if (unlikely(sk_add_backlog(sk, skb,
-					   sk->sk_rcvbuf + sk->sk_sndbuf))) {
-		bh_unlock_sock(sk);
+	} else if (unlikely(sk_add_backlog(meta_sk, skb,
+					   meta_sk->sk_rcvbuf + meta_sk->sk_sndbuf))) {
+		bh_unlock_sock(meta_sk);
 		NET_INC_STATS_BH(net, LINUX_MIB_TCPBACKLOGDROP);
 		goto discard_and_relse;
 	}
-	bh_unlock_sock(sk);
+
+	bh_unlock_sock(meta_sk);
 
 	sock_put(sk);
 	return ret ? -1 : 0;
@@ -1580,6 +1680,18 @@
 			sk = sk2;
 			goto process;
 		}
+#ifdef CONFIG_MPTCP
+		if (th->syn && !th->ack) {
+			int ret = mptcp_lookup_join(skb, inet_twsk(sk));
+
+			if (ret < 0) {
+				tcp_v6_send_reset(NULL, skb);
+				goto discard_it;
+			} else if (ret > 0) {
+				return 0;
+			}
+		}
+#endif
 		/* Fall through to ACK */
 	}
 	case TCP_TW_ACK:
@@ -1629,13 +1741,13 @@
 	}
 }
 
-static struct timewait_sock_ops tcp6_timewait_sock_ops = {
+struct timewait_sock_ops tcp6_timewait_sock_ops = {
 	.twsk_obj_size	= sizeof(struct tcp6_timewait_sock),
 	.twsk_unique	= tcp_twsk_unique,
 	.twsk_destructor= tcp_twsk_destructor,
 };
 
-static const struct inet_connection_sock_af_ops ipv6_specific = {
+const struct inet_connection_sock_af_ops ipv6_specific = {
 	.queue_xmit	   = inet6_csk_xmit,
 	.send_check	   = tcp_v6_send_check,
 	.rebuild_header	   = inet6_sk_rebuild_header,
@@ -1667,7 +1779,7 @@
  *	TCP over IPv4 via INET6 API
  */
 
-static const struct inet_connection_sock_af_ops ipv6_mapped = {
+const struct inet_connection_sock_af_ops ipv6_mapped = {
 	.queue_xmit	   = ip_queue_xmit,
 	.send_check	   = tcp_v4_send_check,
 	.rebuild_header	   = inet_sk_rebuild_header,
@@ -1712,7 +1824,7 @@
 	return 0;
 }
 
-static void tcp_v6_destroy_sock(struct sock *sk)
+void tcp_v6_destroy_sock(struct sock *sk)
 {
 	tcp_v4_destroy_sock(sk);
 	inet6_destroy_sock(sk);
diff -Naur a/net/Kconfig b/net/Kconfig
--- a/net/Kconfig	2013-09-02 22:46:10.000000000 +0200
+++ b/net/Kconfig	2013-10-06 18:26:04.496866147 +0200
@@ -79,6 +79,7 @@
 source "net/ipv4/Kconfig"
 source "net/ipv6/Kconfig"
 source "net/netlabel/Kconfig"
+source "net/mptcp/Kconfig"
 
 endif # if INET
 
diff -Naur a/net/Makefile b/net/Makefile
--- a/net/Makefile	2013-09-02 22:46:10.000000000 +0200
+++ b/net/Makefile	2013-10-06 18:26:04.501866085 +0200
@@ -20,6 +20,7 @@
 obj-$(CONFIG_XFRM)		+= xfrm/
 obj-$(CONFIG_UNIX)		+= unix/
 obj-$(CONFIG_NET)		+= ipv6/
+obj-$(CONFIG_MPTCP)		+= mptcp/
 obj-$(CONFIG_PACKET)		+= packet/
 obj-$(CONFIG_NET_KEY)		+= key/
 obj-$(CONFIG_BRIDGE)		+= bridge/
diff -Naur a/net/mptcp/Kconfig b/net/mptcp/Kconfig
--- a/net/mptcp/Kconfig	1970-01-01 01:00:00.000000000 +0100
+++ b/net/mptcp/Kconfig	2013-10-06 18:26:04.501866085 +0200
@@ -0,0 +1,9 @@
+#
+# MPTCP configuration
+#
+config MPTCP
+        bool "MPTCP protocol"
+        depends on !SYN_COOKIES && !TCP_MD5SIG && (IPV6=y || IPV6=n)
+        ---help---
+          This replaces the normal TCP stack with a Multipath TCP stack,
+          able to use several paths at once.
diff -Naur a/net/mptcp/Makefile b/net/mptcp/Makefile
--- a/net/mptcp/Makefile	1970-01-01 01:00:00.000000000 +0100
+++ b/net/mptcp/Makefile	2013-10-06 18:26:04.501866085 +0200
@@ -0,0 +1,15 @@
+#
+## Makefile for MultiPath TCP support code.
+#
+#
+
+obj-$(CONFIG_MPTCP) += mptcp.o
+
+mptcp-y := mptcp_ctrl.o mptcp_ipv4.o mptcp_ofo_queue.o mptcp_pm.o \
+	   mptcp_output.o mptcp_input.o
+
+obj-$(CONFIG_TCP_CONG_COUPLED) += mptcp_coupled.o
+obj-$(CONFIG_TCP_CONG_OLIA) += mptcp_olia.o
+
+mptcp-$(subst m,y,$(CONFIG_IPV6)) += mptcp_ipv6.o
+
diff -Naur a/net/mptcp/mptcp_coupled.c b/net/mptcp/mptcp_coupled.c
--- a/net/mptcp/mptcp_coupled.c	1970-01-01 01:00:00.000000000 +0100
+++ b/net/mptcp/mptcp_coupled.c	2013-10-06 18:26:04.502866072 +0200
@@ -0,0 +1,273 @@
+/*
+ *	MPTCP implementation - Coupled Congestion Control
+ *
+ *	Initial Design & Implementation:
+ *	Sébastien Barré <[e-mail]>
+ *
+ *	Current Maintainer & Author:
+ *	Christoph Paasch <[e-mail]>
+ *
+ *	Additional authors:
+ *	Jaakko Korkeaniemi <[e-mail]>
+ *	Gregory Detal <[e-mail]>
+ *	Fabien Duchêne <[e-mail]>
+ *	Andreas Seelinger <[e-mail]>
+ *	Lavkesh Lahngir <[e-mail]>
+ *	Andreas Ripke <[e-mail]>
+ *	Vlad Dogaru <[e-mail]>
+ *	Octavian Purdila <[e-mail]>
+ *	John Ronan <[e-mail]>
+ *	Catalin Nicutar <[e-mail]>
+ *	Brandon Heller <[e-mail]>
+ *
+ *
+ *	This program is free software; you can redistribute it and/or
+ *      modify it under the terms of the GNU General Public License
+ *      as published by the Free Software Foundation; either version
+ *      2 of the License, or (at your option) any later version.
+ */
+#include <net/tcp.h>
+#include <net/mptcp.h>
+
+#include <linux/module.h>
+
+/* Scaling is done in the numerator with alpha_scale_num and in the denominator
+ * with alpha_scale_den.
+ *
+ * To downscale, we just need to use alpha_scale.
+ *
+ * We have: alpha_scale = alpha_scale_num / (alpha_scale_den ^ 2)
+ */
+static int alpha_scale_den = 10;
+static int alpha_scale_num = 32;
+static int alpha_scale = 12;
+
+struct mptcp_ccc {
+	u64	alpha;
+	bool	forced_update;
+};
+
+static inline int mptcp_ccc_sk_can_send(const struct sock *sk)
+{
+	return mptcp_sk_can_send(sk) && tcp_sk(sk)->srtt;
+}
+
+static inline u64 mptcp_get_alpha(struct sock *meta_sk)
+{
+	struct mptcp_ccc *mptcp_ccc = inet_csk_ca(meta_sk);
+	return mptcp_ccc->alpha;
+}
+
+static inline void mptcp_set_alpha(struct sock *meta_sk, u64 alpha)
+{
+	struct mptcp_ccc *mptcp_ccc = inet_csk_ca(meta_sk);
+	mptcp_ccc->alpha = alpha;
+}
+
+static inline u64 mptcp_ccc_scale(u32 val, int scale)
+{
+	return (u64) val << scale;
+}
+
+static inline bool mptcp_get_forced(struct sock *meta_sk)
+{
+	struct mptcp_ccc *mptcp_ccc = inet_csk_ca(meta_sk);
+	return mptcp_ccc->forced_update;
+}
+
+static inline void mptcp_set_forced(struct sock *meta_sk, bool force)
+{
+	struct mptcp_ccc *mptcp_ccc = inet_csk_ca(meta_sk);
+	mptcp_ccc->forced_update = force;
+}
+
+static void mptcp_ccc_recalc_alpha(struct sock *sk)
+{
+	struct mptcp_cb *mpcb = tcp_sk(sk)->mpcb;
+	struct sock *sub_sk;
+	int best_cwnd = 0, best_rtt = 0, can_send = 0;
+	u64 max_numerator = 0, sum_denominator = 0, alpha = 1;
+
+	if (!mpcb)
+		return;
+
+	/* Only one subflow left - fall back to normal reno-behavior
+	 * (set alpha to 1) */
+	if (mpcb->cnt_established <= 1)
+		goto exit;
+
+	/* Do regular alpha-calculation for multiple subflows */
+
+	/* Find the max numerator of the alpha-calculation */
+	mptcp_for_each_sk(mpcb, sub_sk) {
+		struct tcp_sock *sub_tp = tcp_sk(sub_sk);
+		u64 tmp;
+
+		if (!mptcp_ccc_sk_can_send(sub_sk))
+			continue;
+
+		can_send++;
+
+		/* We need to look for the path, that provides the max-value.
+		 * Integer-overflow is not possible here, because
+		 * tmp will be in u64.
+		 */
+		tmp = div64_u64(mptcp_ccc_scale(sub_tp->snd_cwnd,
+				alpha_scale_num), sub_tp->srtt * sub_tp->srtt);
+
+		if (tmp >= max_numerator) {
+			max_numerator = tmp;
+			best_cwnd = sub_tp->snd_cwnd;
+			best_rtt = sub_tp->srtt;
+		}
+	}
+
+	/* No subflow is able to send - we don't care anymore */
+	if (unlikely(!can_send))
+		goto exit;
+
+	/* Calculate the denominator */
+	mptcp_for_each_sk(mpcb, sub_sk) {
+		struct tcp_sock *sub_tp = tcp_sk(sub_sk);
+
+		if (!mptcp_ccc_sk_can_send(sub_sk))
+			continue;
+
+		sum_denominator += div_u64(
+				mptcp_ccc_scale(sub_tp->snd_cwnd,
+						alpha_scale_den) * best_rtt,
+						sub_tp->srtt);
+	}
+	sum_denominator *= sum_denominator;
+	if (unlikely(!sum_denominator)) {
+		pr_err("%s: sum_denominator == 0, cnt_established:%d\n",
+		       __func__, mpcb->cnt_established);
+		mptcp_for_each_sk(mpcb, sub_sk) {
+			struct tcp_sock *sub_tp = tcp_sk(sub_sk);
+			pr_err("%s: pi:%d, state:%d\n, rtt:%u, cwnd: %u",
+			       __func__, sub_tp->mptcp->path_index,
+			       sub_sk->sk_state, sub_tp->srtt,
+			       sub_tp->snd_cwnd);
+		}
+	}
+
+	alpha = div64_u64(mptcp_ccc_scale(best_cwnd, alpha_scale_num), sum_denominator);
+
+	if (unlikely(!alpha))
+		alpha = 1;
+
+exit:
+	mptcp_set_alpha(mptcp_meta_sk(sk), alpha);
+}
+
+static void mptcp_ccc_init(struct sock *sk)
+{
+	if (tcp_sk(sk)->mpc) {
+		mptcp_set_forced(mptcp_meta_sk(sk), 0);
+		mptcp_set_alpha(mptcp_meta_sk(sk), 1);
+	}
+	/* If we do not mptcp, behave like reno: return */
+}
+
+static void mptcp_ccc_cwnd_event(struct sock *sk, enum tcp_ca_event event)
+{
+	if (event == CA_EVENT_LOSS)
+		mptcp_ccc_recalc_alpha(sk);
+}
+
+static void mptcp_ccc_set_state(struct sock *sk, u8 ca_state)
+{
+	if (!tcp_sk(sk)->mpc)
+		return;
+
+	mptcp_set_forced(mptcp_meta_sk(sk), 1);
+}
+
+static void mptcp_ccc_cong_avoid(struct sock *sk, u32 ack, u32 in_flight)
+{
+	struct tcp_sock *tp = tcp_sk(sk);
+	struct mptcp_cb *mpcb = tp->mpcb;
+	int snd_cwnd;
+
+	if (!tp->mpc) {
+		tcp_reno_cong_avoid(sk, ack, in_flight);
+		return;
+	}
+
+	if (!tcp_is_cwnd_limited(sk, in_flight))
+		return;
+
+	if (tp->snd_cwnd <= tp->snd_ssthresh) {
+		/* In "safe" area, increase. */
+		tcp_slow_start(tp);
+		mptcp_ccc_recalc_alpha(sk);
+		return;
+	}
+
+	if (mptcp_get_forced(mptcp_meta_sk(sk))) {
+		mptcp_ccc_recalc_alpha(sk);
+		mptcp_set_forced(mptcp_meta_sk(sk), 0);
+	}
+
+	if (mpcb->cnt_established > 1) {
+		u64 alpha = mptcp_get_alpha(mptcp_meta_sk(sk));
+
+		/* This may happen, if at the initialization, the mpcb
+		 * was not yet attached to the sock, and thus
+		 * initializing alpha failed.
+		 */
+		if (unlikely(!alpha))
+			alpha = 1;
+
+		snd_cwnd = (int) div_u64 ((u64) mptcp_ccc_scale(1, alpha_scale),
+						alpha);
+
+		/* snd_cwnd_cnt >= max (scale * tot_cwnd / alpha, cwnd)
+		 * Thus, we select here the max value. */
+		if (snd_cwnd < tp->snd_cwnd)
+			snd_cwnd = tp->snd_cwnd;
+	} else {
+		snd_cwnd = tp->snd_cwnd;
+	}
+
+	if (tp->snd_cwnd_cnt >= snd_cwnd) {
+		if (tp->snd_cwnd < tp->snd_cwnd_clamp) {
+			tp->snd_cwnd++;
+			mptcp_ccc_recalc_alpha(sk);
+		}
+
+		tp->snd_cwnd_cnt = 0;
+	} else {
+		tp->snd_cwnd_cnt++;
+	}
+}
+
+static struct tcp_congestion_ops mptcp_ccc = {
+	.init		= mptcp_ccc_init,
+	.ssthresh	= tcp_reno_ssthresh,
+	.cong_avoid	= mptcp_ccc_cong_avoid,
+	.cwnd_event	= mptcp_ccc_cwnd_event,
+	.set_state	= mptcp_ccc_set_state,
+	.min_cwnd	= tcp_reno_min_cwnd,
+	.owner		= THIS_MODULE,
+	.name		= "coupled",
+};
+
+static int __init mptcp_ccc_register(void)
+{
+	BUILD_BUG_ON(sizeof(struct mptcp_ccc) > ICSK_CA_PRIV_SIZE);
+	return tcp_register_congestion_control(&mptcp_ccc);
+}
+
+static void __exit mptcp_ccc_unregister(void)
+{
+	tcp_unregister_congestion_control(&mptcp_ccc);
+}
+
+module_init(mptcp_ccc_register);
+module_exit(mptcp_ccc_unregister);
+
+MODULE_AUTHOR("Christoph Paasch, Sébastien Barré");
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("MPTCP COUPLED CONGESTION CONTROL");
+MODULE_VERSION("0.1");
diff -Naur a/net/mptcp/mptcp_ctrl.c b/net/mptcp/mptcp_ctrl.c
--- a/net/mptcp/mptcp_ctrl.c	1970-01-01 01:00:00.000000000 +0100
+++ b/net/mptcp/mptcp_ctrl.c	2013-10-06 18:26:04.504866047 +0200
@@ -0,0 +1,1824 @@
+/*
+ *	MPTCP implementation - MPTCP-control
+ *
+ *	Initial Design & Implementation:
+ *	Sébastien Barré <[e-mail]>
+ *
+ *	Current Maintainer & Author:
+ *	Christoph Paasch <[e-mail]>
+ *
+ *	Additional authors:
+ *	Jaakko Korkeaniemi <[e-mail]>
+ *	Gregory Detal <[e-mail]>
+ *	Fabien Duchêne <[e-mail]>
+ *	Andreas Seelinger <[e-mail]>
+ *	Lavkesh Lahngir <[e-mail]>
+ *	Andreas Ripke <[e-mail]>
+ *	Vlad Dogaru <[e-mail]>
+ *	Octavian Purdila <[e-mail]>
+ *	John Ronan <[e-mail]>
+ *	Catalin Nicutar <[e-mail]>
+ *	Brandon Heller <[e-mail]>
+ *
+ *
+ *	This program is free software; you can redistribute it and/or
+ *      modify it under the terms of the GNU General Public License
+ *      as published by the Free Software Foundation; either version
+ *      2 of the License, or (at your option) any later version.
+ */
+
+#include <net/inet_common.h>
+#include <net/inet6_hashtables.h>
+#include <net/ipv6.h>
+#include <net/ip6_checksum.h>
+#include <net/mptcp.h>
+#include <net/mptcp_v4.h>
+#include <net/mptcp_v6.h>
+#include <net/sock.h>
+#include <net/tcp.h>
+#include <net/tcp_states.h>
+#include <net/transp_v6.h>
+#include <net/xfrm.h>
+
+#include <linux/cryptohash.h>
+#include <linux/kconfig.h>
+#include <linux/module.h>
+#include <linux/list.h>
+#include <linux/jhash.h>
+#include <linux/tcp.h>
+#include <linux/net.h>
+#include <linux/in.h>
+#include <linux/random.h>
+#include <linux/inetdevice.h>
+#include <linux/workqueue.h>
+#include <linux/atomic.h>
+#ifdef CONFIG_SYSCTL
+#include <linux/sysctl.h>
+#endif
+
+static struct kmem_cache *mptcp_sock_cache __read_mostly;
+static struct kmem_cache *mptcp_cb_cache __read_mostly;
+static struct kmem_cache *mptcp_tw_cache __read_mostly;
+
+int sysctl_mptcp_ndiffports __read_mostly = 1;
+int sysctl_mptcp_enabled __read_mostly = 1;
+int sysctl_mptcp_checksum __read_mostly = 1;
+int sysctl_mptcp_debug __read_mostly;
+EXPORT_SYMBOL(sysctl_mptcp_debug);
+int sysctl_mptcp_syn_retries __read_mostly = MPTCP_SYN_RETRIES;
+
+bool mptcp_init_failed __read_mostly;
+
+#ifdef CONFIG_SYSCTL
+static struct ctl_table mptcp_table[] = {
+	{
+		.procname = "mptcp_ndiffports",
+		.data = &sysctl_mptcp_ndiffports,
+		.maxlen = sizeof(int),
+		.mode = 0644,
+		.proc_handler = &proc_dointvec
+	},
+	{
+		.procname = "mptcp_enabled",
+		.data = &sysctl_mptcp_enabled,
+		.maxlen = sizeof(int),
+		.mode = 0644,
+		.proc_handler = &proc_dointvec
+	},
+	{
+		.procname = "mptcp_checksum",
+		.data = &sysctl_mptcp_checksum,
+		.maxlen = sizeof(int),
+		.mode = 0644,
+		.proc_handler = &proc_dointvec
+	},
+	{
+		.procname = "mptcp_debug",
+		.data = &sysctl_mptcp_debug,
+		.maxlen = sizeof(int),
+		.mode = 0644,
+		.proc_handler = &proc_dointvec
+	},
+	{
+		.procname = "mptcp_syn_retries",
+		.data = &sysctl_mptcp_syn_retries,
+		.maxlen = sizeof(int),
+		.mode = 0644,
+		.proc_handler = &proc_dointvec
+	},
+	{ }
+};
+#endif
+
+static struct sock *mptcp_syn_recv_sock(struct sock *sk, struct sk_buff *skb,
+					struct request_sock *req,
+					struct dst_entry *dst)
+{
+#if IS_ENABLED(CONFIG_IPV6)
+	if (sk->sk_family == AF_INET6)
+		return tcp_v6_syn_recv_sock(sk, skb, req, dst);
+
+	/* sk->sk_family == AF_INET */
+	if (req->rsk_ops->family == AF_INET6)
+		return mptcp_v6v4_syn_recv_sock(sk, skb, req, dst);
+#endif
+
+	/* sk->sk_family == AF_INET && req->rsk_ops->family == AF_INET */
+	return tcp_v4_syn_recv_sock(sk, skb, req, dst);
+}
+
+struct sock *mptcp_select_ack_sock(const struct sock *meta_sk, int copied)
+{
+	struct tcp_sock *meta_tp = tcp_sk(meta_sk);
+	struct sock *sk, *subsk = NULL;
+	u32 max_data_seq = 0;
+	/* max_data_seq initialized to correct compiler-warning.
+	 * But the initialization is handled by max_data_seq_set
+	 */
+	short max_data_seq_set = 0;
+	u32 min_time = 0xffffffff;
+
+	/* How do we select the subflow to send the window-update on?
+	 *
+	 * 1. He has to be in a state where he can send an ack.
+	 * 2. He has to be one of those subflow who recently
+	 *    contributed to the received stream
+	 *    (this guarantees a working subflow)
+	 *    a) its latest data_seq received is after the original
+	 *       copied_seq.
+	 *       We select the one with the lowest rtt, so that the
+	 *       window-update reaches our peer the fastest.
+	 *    b) if no subflow has this kind of data_seq (e.g., very
+	 *       strange meta-level retransmissions going on), we take
+	 *       the subflow who last sent the highest data_seq.
+	 */
+	mptcp_for_each_sk(meta_tp->mpcb, sk) {
+		struct tcp_sock *tp = tcp_sk(sk);
+
+		if (!mptcp_sk_can_send_ack(sk))
+			continue;
+
+		/* Select among those who contributed to the
+		 * current receive-queue.
+		 */
+		if (copied && after(tp->mptcp->last_data_seq, meta_tp->copied_seq - copied)) {
+			if (tp->srtt < min_time) {
+				min_time = tp->srtt;
+				subsk = sk;
+				max_data_seq_set = 0;
+			}
+			continue;
+		}
+
+		if (!subsk && !max_data_seq_set) {
+			max_data_seq = tp->mptcp->last_data_seq;
+			max_data_seq_set = 1;
+			subsk = sk;
+		}
+
+		/* Otherwise, take the one with the highest data_seq */
+		if ((!subsk || max_data_seq_set) &&
+		    after(tp->mptcp->last_data_seq, max_data_seq)) {
+			max_data_seq = tp->mptcp->last_data_seq;
+			subsk = sk;
+		}
+	}
+
+	if (!subsk) {
+		mptcp_debug("%s subsk is null, copied %d, cseq %u\n", __func__,
+			    copied, meta_tp->copied_seq);
+		mptcp_for_each_sk(meta_tp->mpcb, sk) {
+			struct tcp_sock *tp = tcp_sk(sk);
+			mptcp_debug("%s pi %d state %u last_dseq %u\n",
+				    __func__, tp->mptcp->path_index, sk->sk_state,
+				    tp->mptcp->last_data_seq);
+		}
+	}
+
+	return subsk;
+}
+
+static void mptcp_sock_def_error_report(struct sock *sk)
+{
+	struct mptcp_cb *mpcb = tcp_sk(sk)->mpcb;
+
+	if (!sock_flag(sk, SOCK_DEAD))
+		mptcp_sub_close(sk, 0);
+
+	if (mpcb->infinite_mapping_rcv || mpcb->infinite_mapping_snd ||
+	    mpcb->send_infinite_mapping) {
+		struct sock *meta_sk = mptcp_meta_sk(sk);
+
+		meta_sk->sk_err = sk->sk_err;
+		meta_sk->sk_err_soft = sk->sk_err_soft;
+
+		if (!sock_flag(meta_sk, SOCK_DEAD))
+			meta_sk->sk_error_report(meta_sk);
+
+		tcp_done(meta_sk);
+	}
+
+	sk->sk_err = 0;
+	return;
+}
+
+static void mptcp_mpcb_put(struct mptcp_cb *mpcb)
+{
+	if (atomic_dec_and_test(&mpcb->refcnt))
+		kmem_cache_free(mptcp_cb_cache, mpcb);
+}
+
+static void mptcp_sock_destruct(struct sock *sk)
+{
+	struct tcp_sock *tp = tcp_sk(sk);
+
+	inet_sock_destruct(sk);
+
+	kmem_cache_free(mptcp_sock_cache, tp->mptcp);
+	tp->mptcp = NULL;
+
+	if (!is_meta_sk(sk) && !tp->was_meta_sk) {
+		/* Taken when mpcb pointer was set */
+		sock_put(mptcp_meta_sk(sk));
+		mptcp_mpcb_put(tp->mpcb);
+	} else {
+		struct mptcp_cb *mpcb = tp->mpcb;
+		struct mptcp_tw *mptw;
+
+		/* The mpcb is disappearing - we can make the final
+		 * update to the rcv_nxt of the time-wait-sock and remove
+		 * its reference to the mpcb.
+		 */
+		spin_lock_bh(&mpcb->tw_lock);
+		list_for_each_entry_rcu(mptw, &mpcb->tw_list, list) {
+			list_del_rcu(&mptw->list);
+			mptw->in_list = 0;
+			mptcp_mpcb_put(mpcb);
+			rcu_assign_pointer(mptw->mpcb, NULL);
+		}
+		spin_unlock_bh(&mpcb->tw_lock);
+
+		mptcp_mpcb_put(mpcb);
+
+		mptcp_debug("%s destroying meta-sk\n", __func__);
+	}
+}
+
+void mptcp_destroy_sock(struct sock *sk)
+{
+	if (is_meta_sk(sk)) {
+		struct sock *sk_it, *tmpsk;
+
+		__skb_queue_purge(&tcp_sk(sk)->mpcb->reinject_queue);
+		mptcp_purge_ofo_queue(tcp_sk(sk));
+
+		/* We have to close all remaining subflows. Normally, they
+		 * should all be about to get closed. But, if the kernel is
+		 * forcing a closure (e.g., tcp_write_err), the subflows might
+		 * not have been closed properly (as we are waiting for the
+		 * DATA_ACK of the DATA_FIN).
+		 */
+		mptcp_for_each_sk_safe(tcp_sk(sk)->mpcb, sk_it, tmpsk) {
+			/* Already did call tcp_close - waiting for graceful
+			 * closure.
+			 */
+			if (tcp_sk(sk_it)->closing)
+				continue;
+
+			/* Allow the delayed work first to prevent time-wait state */
+			if (delayed_work_pending(&tcp_sk(sk_it)->mptcp->work))
+				continue;
+
+			mptcp_sub_close(sk_it, 0);
+		}
+	} else {
+		mptcp_del_sock(sk);
+	}
+}
+
+static void mptcp_set_state(struct sock *sk)
+{
+	struct sock *meta_sk = mptcp_meta_sk(sk);
+
+	/* Meta is not yet established - wake up the application */
+	if ((1 << meta_sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV) &&
+	    sk->sk_state == TCP_ESTABLISHED) {
+		tcp_set_state(meta_sk, TCP_ESTABLISHED);
+
+		if (!sock_flag(meta_sk, SOCK_DEAD)) {
+			meta_sk->sk_state_change(meta_sk);
+			sk_wake_async(meta_sk, SOCK_WAKE_IO, POLL_OUT);
+		}
+	}
+
+	if (sk->sk_state == TCP_ESTABLISHED) {
+		tcp_sk(sk)->mptcp->establish_increased = 1;
+		tcp_sk(sk)->mpcb->cnt_established++;
+	}
+}
+
+void mptcp_set_keepalive(struct sock *sk, int val)
+{
+	struct sock *sk_it;
+
+	mptcp_for_each_sk(tcp_sk(sk)->mpcb, sk_it) {
+		tcp_set_keepalive(sk_it, val);
+		sock_valbool_flag(sk, SOCK_KEEPOPEN, val);
+	}
+}
+
+u32 mptcp_secret[MD5_MESSAGE_BYTES / 4] ____cacheline_aligned;
+u32 mptcp_key_seed = 0;
+
+void mptcp_key_sha1(u64 key, u32 *token, u64 *idsn)
+{
+	u32 workspace[SHA_WORKSPACE_WORDS];
+	u32 mptcp_hashed_key[SHA_DIGEST_WORDS];
+	u8 input[64];
+	int i;
+
+	memset(workspace, 0, sizeof(workspace));
+
+	/* Initialize input with appropriate padding */
+	memset(&input[9], 0, sizeof(input) - 10); /* -10, because the last byte
+						   * is explicitly set too */
+	memcpy(input, &key, sizeof(key)); /* Copy key to the msg beginning */
+	input[8] = 0x80; /* Padding: First bit after message = 1 */
+	input[63] = 0x40; /* Padding: Length of the message = 64 bits */
+
+	sha_init(mptcp_hashed_key);
+	sha_transform(mptcp_hashed_key, input, workspace);
+
+	for (i = 0; i < 5; i++)
+		mptcp_hashed_key[i] = cpu_to_be32(mptcp_hashed_key[i]);
+
+	if (token)
+		*token = mptcp_hashed_key[0];
+	if (idsn)
+		*idsn = *((u64 *)&mptcp_hashed_key[3]);
+}
+
+void mptcp_hmac_sha1(u8 *key_1, u8 *key_2, u8 *rand_1, u8 *rand_2,
+		       u32 *hash_out)
+{
+	u32 workspace[SHA_WORKSPACE_WORDS];
+	u8 input[128]; /* 2 512-bit blocks */
+	int i;
+
+	memset(workspace, 0, sizeof(workspace));
+
+	/* Generate key xored with ipad */
+	memset(input, 0x36, 64);
+	for (i = 0; i < 8; i++)
+		input[i] ^= key_1[i];
+	for (i = 0; i < 8; i++)
+		input[i + 8] ^= key_2[i];
+
+	memcpy(&input[64], rand_1, 4);
+	memcpy(&input[68], rand_2, 4);
+	input[72] = 0x80; /* Padding: First bit after message = 1 */
+	memset(&input[73], 0, 53);
+
+	/* Padding: Length of the message = 512 + 64 bits */
+	input[126] = 0x02;
+	input[127] = 0x40;
+
+	sha_init(hash_out);
+	sha_transform(hash_out, input, workspace);
+	memset(workspace, 0, sizeof(workspace));
+
+	sha_transform(hash_out, &input[64], workspace);
+	memset(workspace, 0, sizeof(workspace));
+
+	for (i = 0; i < 5; i++)
+		hash_out[i] = cpu_to_be32(hash_out[i]);
+
+	/* Prepare second part of hmac */
+	memset(input, 0x5C, 64);
+	for (i = 0; i < 8; i++)
+		input[i] ^= key_1[i];
+	for (i = 0; i < 8; i++)
+		input[i + 8] ^= key_2[i];
+
+	memcpy(&input[64], hash_out, 20);
+	input[84] = 0x80;
+	memset(&input[85], 0, 41);
+
+	/* Padding: Length of the message = 512 + 160 bits */
+	input[126] = 0x02;
+	input[127] = 0xA0;
+
+	sha_init(hash_out);
+	sha_transform(hash_out, input, workspace);
+	memset(workspace, 0, sizeof(workspace));
+
+	sha_transform(hash_out, &input[64], workspace);
+
+	for (i = 0; i < 5; i++)
+		hash_out[i] = cpu_to_be32(hash_out[i]);
+}
+
+static void mptcp_mpcb_inherit_sockopts(struct sock *meta_sk, struct sock *master_sk)
+{
+	/* Socket-options handled by mptcp_inherit_sk while creating the meta-sk.
+	 * ======
+	 * SO_SNDBUF, SO_SNDBUFFORCE, SO_RCVBUF, SO_RCVBUFFORCE, SO_RCVLOWAT,
+	 * SO_RCVTIMEO, SO_SNDTIMEO, SO_ATTACH_FILTER, SO_DETACH_FILTER,
+	 * TCP_NODELAY, TCP_CORK
+	 *
+	 * Socket-options handled in this function here
+	 * ======
+	 * SO_KEEPALIVE
+	 * TCP_KEEP*
+	 * TCP_DEFER_ACCEPT
+	 *
+	 * Socket-options on the todo-list
+	 * ======
+	 * SO_BINDTODEVICE - should probably prevent creation of new subsocks
+	 *		     across other devices. - what about the api-draft?
+	 * SO_DEBUG
+	 * SO_REUSEADDR - probably we don't care about this
+	 * SO_DONTROUTE, SO_BROADCAST
+	 * SO_OOBINLINE
+	 * SO_LINGER
+	 * SO_TIMESTAMP* - I don't think this is of concern for a SOCK_STREAM
+	 * SO_PASSSEC - I don't think this is of concern for a SOCK_STREAM
+	 * SO_RXQ_OVFL
+	 * TCP_COOKIE_TRANSACTIONS
+	 * TCP_MAXSEG
+	 * TCP_THIN_* - Handled by mptcp_inherit_sk, but we need to support this
+	 *		in mptcp_retransmit_timer. AND we need to check what is
+	 *		about the subsockets.
+	 * TCP_LINGER2
+	 * TCP_WINDOW_CLAMP
+	 * TCP_USER_TIMEOUT
+	 * TCP_MD5SIG
+	 *
+	 * Socket-options of no concern for the meta-socket (but for the subsocket)
+	 * ======
+	 * SO_PRIORITY
+	 * SO_MARK
+	 * TCP_CONGESTION
+	 * TCP_SYNCNT
+	 * TCP_QUICKACK
+	 */
+	struct tcp_sock *meta_tp = tcp_sk(meta_sk);
+
+	/****** KEEPALIVE-handler ******/
+
+	/* Keepalive-timer has been started already, but it is handled at the
+	 * subflow level.
+	 */
+	if (sock_flag(meta_sk, SOCK_KEEPOPEN)) {
+		inet_csk_delete_keepalive_timer(meta_sk);
+		inet_csk_reset_keepalive_timer(master_sk, keepalive_time_when(meta_tp));
+	}
+
+	/****** DEFER_ACCEPT-handler ******/
+
+	/* DEFER_ACCEPT is not of concern for new subflows - we always accept
+	 * them
+	 */
+	inet_csk(meta_sk)->icsk_accept_queue.rskq_defer_accept = 0;
+}
+
+static void mptcp_sub_inherit_sockopts(struct sock *meta_sk, struct sock *sub_sk)
+{
+	struct tcp_sock *meta_tp = tcp_sk(meta_sk);
+	/* Keepalive is handled at the subflow-level */
+	if (sock_flag(meta_sk, SOCK_KEEPOPEN)) {
+		inet_csk_reset_keepalive_timer(sub_sk, keepalive_time_when(meta_tp));
+		sock_valbool_flag(sub_sk, SOCK_KEEPOPEN, keepalive_time_when(meta_tp));
+	}
+
+	/* IP_TOS also goes to the subflow. */
+	if (inet_sk(sub_sk)->tos != inet_sk(meta_sk)->tos) {
+		inet_sk(sub_sk)->tos = inet_sk(meta_sk)->tos;
+		sub_sk->sk_priority = meta_sk->sk_priority;
+		sk_dst_reset(sub_sk);
+	}
+
+	/* Inheris SO_REUSEADDR */
+	sub_sk->sk_reuse = meta_sk->sk_reuse;
+}
+
+int mptcp_backlog_rcv(struct sock *meta_sk, struct sk_buff *skb)
+{
+	/* skb-sk may be NULL if we receive a packet immediatly after the
+	 * SYN/ACK + MP_CAPABLE.
+	 */
+	struct sock *sk = skb->sk ? skb->sk : meta_sk;
+	int ret = 0;
+
+	if (unlikely(!atomic_inc_not_zero(&sk->sk_refcnt))) {
+		kfree_skb(skb);
+		return 0;
+	}
+
+	if (sk->sk_family == AF_INET)
+		ret = tcp_v4_do_rcv(sk, skb);
+#if IS_ENABLED(CONFIG_IPV6)
+	else
+		ret = tcp_v6_do_rcv(sk, skb);
+#endif
+
+	sock_put(sk);
+	return ret;
+}
+
+struct lock_class_key meta_key;
+struct lock_class_key meta_slock_key;
+
+/* Code heavily inspired from sk_clone() */
+static int mptcp_inherit_sk(const struct sock *sk, struct sock *newsk,
+			    int family, const gfp_t flags)
+{
+	struct sk_filter *filter;
+	struct proto *prot = newsk->sk_prot;
+	const struct inet_connection_sock_af_ops *af_ops = inet_csk(newsk)->icsk_af_ops;
+#ifdef CONFIG_SECURITY_NETWORK
+	void *sptr = newsk->sk_security;
+#endif
+
+	if (sk->sk_family == AF_INET) {
+		memcpy(newsk, sk, offsetof(struct sock, sk_dontcopy_begin));
+		memcpy(&newsk->sk_dontcopy_end, &sk->sk_dontcopy_end,
+		       sizeof(struct tcp_sock) - offsetof(struct sock, sk_dontcopy_end));
+	} else {
+		memcpy(newsk, sk, offsetof(struct sock, sk_dontcopy_begin));
+		memcpy(&newsk->sk_dontcopy_end, &sk->sk_dontcopy_end,
+		       sizeof(struct tcp6_sock) - offsetof(struct sock, sk_dontcopy_end));
+	}
+
+#ifdef CONFIG_SECURITY_NETWORK
+	newsk->sk_security = sptr;
+	security_sk_clone(sk, newsk);
+#endif
+
+	/* Has been changed by sock_copy above - we may need an IPv6-socket */
+	newsk->sk_family = family;
+	newsk->sk_prot = prot;
+	newsk->sk_prot_creator = prot;
+	inet_csk(newsk)->icsk_af_ops = af_ops;
+
+	/* We don't yet have the mptcp-point. Thus we still need inet_sock_destruct */
+	newsk->sk_destruct = inet_sock_destruct;
+
+	/* SANITY */
+	get_net(sock_net(newsk));
+	sk_node_init(&newsk->sk_node);
+	sock_lock_init_class_and_name(newsk, "slock-AF_INET-MPTCP",
+				      &meta_slock_key, "sk_lock-AF_INET-MPTCP",
+				      &meta_key);
+
+	/* Unlocks are in:
+	 *
+	 * 1. If we are creating the master-sk
+	 *	* on client-side in tcp_rcv_state_process, "case TCP_SYN_SENT"
+	 *	* on server-side in tcp_child_process
+	 * 2. If we are creating another subsock
+	 *	* Also in tcp_child_process
+	 */
+	bh_lock_sock(newsk);
+	newsk->sk_backlog.head = NULL;
+	newsk->sk_backlog.tail = NULL;
+	newsk->sk_backlog.len = 0;
+
+	atomic_set(&newsk->sk_rmem_alloc, 0);
+	atomic_set(&newsk->sk_wmem_alloc, 1);
+	atomic_set(&newsk->sk_omem_alloc, 0);
+
+	skb_queue_head_init(&newsk->sk_receive_queue);
+	skb_queue_head_init(&newsk->sk_write_queue);
+#ifdef CONFIG_NET_DMA
+	skb_queue_head_init(&newsk->sk_async_wait_queue);
+#endif
+
+	spin_lock_init(&newsk->sk_dst_lock);
+	rwlock_init(&newsk->sk_callback_lock);
+	lockdep_set_class_and_name(&newsk->sk_callback_lock,
+				   af_callback_keys + newsk->sk_family,
+				   af_family_clock_key_strings[newsk->sk_family]);
+	newsk->sk_dst_cache	= NULL;
+	newsk->sk_rx_dst	= NULL;
+	newsk->sk_wmem_queued	= 0;
+	newsk->sk_forward_alloc = 0;
+	newsk->sk_send_head	= NULL;
+	newsk->sk_userlocks	= sk->sk_userlocks & ~SOCK_BINDPORT_LOCK;
+
+	tcp_sk(newsk)->mptcp = NULL;
+
+	sock_reset_flag(newsk, SOCK_DONE);
+	skb_queue_head_init(&newsk->sk_error_queue);
+
+	filter = rcu_dereference_protected(newsk->sk_filter, 1);
+	if (filter != NULL)
+		sk_filter_charge(newsk, filter);
+
+	if (unlikely(xfrm_sk_clone_policy(newsk))) {
+		/* It is still raw copy of parent, so invalidate
+		 * destructor and make plain sk_free()
+		 */
+		newsk->sk_destruct = NULL;
+		bh_unlock_sock(newsk);
+		sk_free(newsk);
+		newsk = NULL;
+		return -ENOMEM;
+	}
+
+	newsk->sk_err	   = 0;
+	newsk->sk_priority = 0;
+	/* Before updating sk_refcnt, we must commit prior changes to memory
+	 * (Documentation/RCU/rculist_nulls.txt for details)
+	 */
+	smp_wmb();
+	atomic_set(&newsk->sk_refcnt, 2);
+
+	/* Increment the counter in the same struct proto as the master
+	 * sock (sk_refcnt_debug_inc uses newsk->sk_prot->socks, that
+	 * is the same as sk->sk_prot->socks, as this field was copied
+	 * with memcpy).
+	 *
+	 * This _changes_ the previous behaviour, where
+	 * tcp_create_openreq_child always was incrementing the
+	 * equivalent to tcp_prot->socks (inet_sock_nr), so this have
+	 * to be taken into account in all callers. -acme
+	 */
+	sk_refcnt_debug_inc(newsk);
+	sk_set_socket(newsk, NULL);
+	newsk->sk_wq = NULL;
+
+	if (newsk->sk_prot->sockets_allocated)
+		percpu_counter_inc(newsk->sk_prot->sockets_allocated);
+
+	if (sock_flag(newsk, SOCK_TIMESTAMP) ||
+	    sock_flag(newsk, SOCK_TIMESTAMPING_RX_SOFTWARE))
+		net_enable_timestamp();
+
+	return 0;
+}
+
+int mptcp_alloc_mpcb(struct sock *meta_sk, __u64 remote_key, u32 window)
+{
+	struct mptcp_cb *mpcb;
+	struct sock *master_sk;
+	struct inet_connection_sock *master_icsk, *meta_icsk = inet_csk(meta_sk);
+	struct tcp_sock *master_tp, *meta_tp = tcp_sk(meta_sk);
+	struct sk_buff *skb, *tmp;
+	u64 idsn;
+
+	master_sk = sk_prot_alloc(meta_sk->sk_prot, GFP_ATOMIC | __GFP_ZERO,
+				  meta_sk->sk_family);
+	if (!master_sk)
+		return -ENOBUFS;
+
+	master_tp = tcp_sk(master_sk);
+	master_icsk = inet_csk(master_sk);
+
+	/* Need to set this here - it is needed by mptcp_inherit_sk */
+	master_sk->sk_prot = meta_sk->sk_prot;
+	master_sk->sk_prot_creator = meta_sk->sk_prot;
+	master_icsk->icsk_af_ops = meta_icsk->icsk_af_ops;
+
+	mpcb = kmem_cache_zalloc(mptcp_cb_cache, GFP_ATOMIC);
+	if (!mpcb) {
+		sk_free(master_sk);
+		return -ENOBUFS;
+	}
+
+	/* master_sk inherits from meta_sk */
+	if (mptcp_inherit_sk(meta_sk, master_sk, meta_sk->sk_family, GFP_ATOMIC)) {
+		kmem_cache_free(mptcp_cb_cache, mpcb);
+		return -ENOBUFS;
+	}
+
+#if IS_ENABLED(CONFIG_IPV6)
+	if (meta_icsk->icsk_af_ops == &ipv6_mapped) {
+		struct ipv6_pinfo *newnp, *np = inet6_sk(meta_sk);
+
+		inet_sk(master_sk)->pinet6 = &((struct tcp6_sock *)master_sk)->inet6;
+
+		newnp = inet6_sk(master_sk);
+		memcpy(newnp, np, sizeof(struct ipv6_pinfo));
+
+		newnp->ipv6_mc_list = NULL;
+		newnp->ipv6_ac_list = NULL;
+		newnp->ipv6_fl_list = NULL;
+		newnp->opt = NULL;
+		newnp->pktoptions = NULL;
+		(void)xchg(&newnp->rxpmtu, NULL);
+	} else if (meta_sk->sk_family == AF_INET6) {
+		struct ipv6_pinfo *newnp;
+
+		/* Meta is IPv4. Initialize pinet6 for the master-sk. */
+		inet_sk(master_sk)->pinet6 = &((struct tcp6_sock *)master_sk)->inet6;
+
+		newnp = inet6_sk(master_sk);
+
+		newnp->hop_limit	= -1;
+		newnp->mcast_hops	= IPV6_DEFAULT_MCASTHOPS;
+		newnp->mc_loop	= 1;
+		newnp->pmtudisc	= IPV6_PMTUDISC_WANT;
+		newnp->ipv6only	= sock_net(master_sk)->ipv6.sysctl.bindv6only;
+	}
+#endif
+
+	meta_tp->mptcp = kmem_cache_zalloc(mptcp_sock_cache, GFP_ATOMIC);
+	if (!meta_tp->mptcp) {
+		kmem_cache_free(mptcp_cb_cache, mpcb);
+		sk_free(master_sk);
+		return -ENOBUFS;
+	}
+
+	/* Store the keys and generate the peer's token */
+	mpcb->mptcp_loc_key = meta_tp->mptcp_loc_key;
+	mpcb->mptcp_loc_token = meta_tp->mptcp_loc_token;
+
+	/* Generate Initial data-sequence-numbers */
+	mptcp_key_sha1(mpcb->mptcp_loc_key, NULL, &idsn);
+	idsn = ntohll(idsn) + 1;
+	mpcb->snd_high_order[0] = idsn >> 32;
+	mpcb->snd_high_order[1] = mpcb->snd_high_order[0] - 1;
+
+	meta_tp->write_seq = (u32)idsn;
+	meta_tp->snd_sml = meta_tp->write_seq;
+	meta_tp->snd_una = meta_tp->write_seq;
+	meta_tp->snd_nxt = meta_tp->write_seq;
+	meta_tp->pushed_seq = meta_tp->write_seq;
+	meta_tp->snd_up = meta_tp->write_seq;
+
+	mpcb->mptcp_rem_key = remote_key;
+	mptcp_key_sha1(mpcb->mptcp_rem_key, &mpcb->mptcp_rem_token, &idsn);
+	idsn = ntohll(idsn) + 1;
+	mpcb->rcv_high_order[0] = idsn >> 32;
+	mpcb->rcv_high_order[1] = mpcb->rcv_high_order[0] + 1;
+	meta_tp->copied_seq = (u32) idsn;
+	meta_tp->rcv_nxt = (u32) idsn;
+	meta_tp->rcv_wup = (u32) idsn;
+
+	meta_tp->snd_wl1 = meta_tp->rcv_nxt - 1;
+	meta_tp->snd_wnd = window;
+	meta_tp->retrans_stamp = 0; /* Set in tcp_connect() */
+
+	meta_tp->packets_out = 0;
+	meta_tp->mptcp->snt_isn = meta_tp->write_seq; /* Initial data-sequence-number */
+	meta_icsk->icsk_probes_out = 0;
+
+	/* Set mptcp-pointers */
+	master_tp->mpcb = mpcb;
+	master_tp->meta_sk = meta_sk;
+	meta_tp->mpcb = mpcb;
+	meta_tp->meta_sk = meta_sk;
+	mpcb->meta_sk = meta_sk;
+	mpcb->master_sk = master_sk;
+
+	meta_tp->mpc = 1;
+	meta_tp->mptcp->attached = 0;
+	meta_tp->was_meta_sk = 0;
+
+	/* Initialize the queues */
+	skb_queue_head_init(&mpcb->reinject_queue);
+	skb_queue_head_init(&master_tp->out_of_order_queue);
+	tcp_prequeue_init(master_tp);
+
+	master_tp->tsq_flags = 0;
+
+	/* Copy the write-queue from the meta down to the master.
+	 * This is necessary to get the SYN to the master-write-queue.
+	 * No other data can be queued, before tcp_sendmsg waits for the
+	 * connection to finish.
+	 */
+	skb_queue_walk_safe(&meta_sk->sk_write_queue, skb, tmp) {
+		skb_unlink(skb, &meta_sk->sk_write_queue);
+		skb_queue_tail(&master_sk->sk_write_queue, skb);
+
+		master_sk->sk_wmem_queued += skb->truesize;
+		sk_mem_charge(master_sk, skb->truesize);
+	}
+
+	meta_sk->sk_wmem_queued = 0;
+	meta_sk->sk_forward_alloc = 0;
+
+	mutex_init(&mpcb->mutex);
+
+	/* Initialize workqueue-struct */
+	INIT_WORK(&mpcb->subflow_work, mptcp_create_subflow_worker);
+	INIT_DELAYED_WORK(&mpcb->subflow_retry_work, mptcp_retry_subflow_worker);
+	INIT_WORK(&mpcb->address_work, mptcp_address_worker);
+
+	/* Init the accept_queue structure, we support a queue of 32 pending
+	 * connections, it does not need to be huge, since we only store  here
+	 * pending subflow creations.
+	 */
+	if (reqsk_queue_alloc(&meta_icsk->icsk_accept_queue, 32, GFP_ATOMIC)) {
+		inet_put_port(master_sk);
+		kmem_cache_free(mptcp_sock_cache, meta_tp->mptcp);
+		kmem_cache_free(mptcp_cb_cache, mpcb);
+		sk_free(master_sk);
+		meta_tp->mpc = 0;
+		return -ENOMEM;
+	}
+
+	/* Redefine function-pointers as the meta-sk is now fully ready */
+	meta_sk->sk_backlog_rcv = mptcp_backlog_rcv;
+	meta_sk->sk_destruct = mptcp_sock_destruct;
+	mpcb->syn_recv_sock = mptcp_syn_recv_sock;
+
+	/* Meta-level retransmit timer */
+	meta_icsk->icsk_rto *= 2; /* Double of initial - rto */
+
+	tcp_init_xmit_timers(master_sk);
+	/* Has been set for sending out the SYN */
+	inet_csk_clear_xmit_timer(meta_sk, ICSK_TIME_RETRANS);
+
+	if (!meta_tp->inside_tk_table) {
+		/* Adding the meta_tp in the token hashtable - coming from server-side */
+		rcu_read_lock();
+		spin_lock(&mptcp_tk_hashlock);
+
+		__mptcp_hash_insert(meta_tp, mpcb->mptcp_loc_token);
+
+		spin_unlock(&mptcp_tk_hashlock);
+		rcu_read_unlock();
+	}
+	master_tp->inside_tk_table = 0;
+
+	/* Init time-wait stuff */
+	INIT_LIST_HEAD(&mpcb->tw_list);
+	spin_lock_init(&mpcb->tw_lock);
+
+	mptcp_mpcb_inherit_sockopts(meta_sk, master_sk);
+
+	mpcb->orig_sk_rcvbuf = meta_sk->sk_rcvbuf;
+	mpcb->orig_sk_sndbuf = meta_sk->sk_sndbuf;
+	mpcb->orig_window_clamp = meta_tp->window_clamp;
+
+	/* The meta is directly linked - set refcnt to 1 */
+	atomic_set(&mpcb->refcnt, 1);
+
+	mptcp_debug("%s: created mpcb with token %#x\n",
+		    __func__, mpcb->mptcp_loc_token);
+
+	return 0;
+}
+
+struct sock *mptcp_sk_clone(const struct sock *sk, int family,
+			    const gfp_t priority)
+{
+	struct sock *newsk = NULL;
+
+	if (family == AF_INET && sk->sk_family == AF_INET) {
+		newsk = sk_prot_alloc(&tcp_prot, priority, family);
+		if (!newsk)
+			return NULL;
+
+		/* Set these pointers - they are needed by mptcp_inherit_sk */
+		newsk->sk_prot = &tcp_prot;
+		newsk->sk_prot_creator = &tcp_prot;
+		inet_csk(newsk)->icsk_af_ops = &ipv4_specific;
+		newsk->sk_family = AF_INET;
+	}
+#if IS_ENABLED(CONFIG_IPV6)
+	else {
+		newsk = sk_prot_alloc(&tcpv6_prot, priority, family);
+		if (!newsk)
+			return NULL;
+
+		newsk->sk_prot = &tcpv6_prot;
+		newsk->sk_prot_creator = &tcpv6_prot;
+		if (family == AF_INET)
+			inet_csk(newsk)->icsk_af_ops = &ipv6_mapped;
+		else
+			inet_csk(newsk)->icsk_af_ops = &ipv6_specific;
+		newsk->sk_family = AF_INET6;
+	}
+#endif
+
+	if (mptcp_inherit_sk(sk, newsk, family, priority))
+		return NULL;
+
+	return newsk;
+}
+
+void mptcp_fallback_meta_sk(struct sock *meta_sk)
+{
+	kfree(inet_csk(meta_sk)->icsk_accept_queue.listen_opt);
+	kmem_cache_free(mptcp_sock_cache, tcp_sk(meta_sk)->mptcp);
+	kmem_cache_free(mptcp_cb_cache, tcp_sk(meta_sk)->mpcb);
+}
+
+int mptcp_add_sock(struct sock *meta_sk, struct sock *sk, u8 rem_id,
+		   gfp_t flags)
+{
+	struct mptcp_cb *mpcb = tcp_sk(meta_sk)->mpcb;
+	struct tcp_sock *tp = tcp_sk(sk);
+
+	tp->mptcp = kmem_cache_zalloc(mptcp_sock_cache, flags);
+	if (!tp->mptcp)
+		return -ENOMEM;
+
+	tp->mptcp->path_index = mptcp_set_new_pathindex(mpcb);
+	/* No more space for more subflows? */
+	if (!tp->mptcp->path_index) {
+		kmem_cache_free(mptcp_sock_cache, tp->mptcp);
+		return -EPERM;
+	}
+
+	tp->mptcp->tp = tp;
+	tp->mpcb = mpcb;
+	tp->meta_sk = meta_sk;
+	tp->mpc = 1;
+	tp->mptcp->rem_id = rem_id;
+	tp->mptcp->last_rbuf_opti = tcp_time_stamp;
+
+	/* The corresponding sock_put is in mptcp_sock_destruct(). It cannot be
+	 * included in mptcp_del_sock(), because the mpcb must remain alive
+	 * until the last subsocket is completely destroyed.
+	 */
+	sock_hold(meta_sk);
+	atomic_inc(&mpcb->refcnt);
+
+	tp->mptcp->next = mpcb->connection_list;
+	mpcb->connection_list = tp;
+	tp->mptcp->attached = 1;
+
+	mpcb->cnt_subflows++;
+	atomic_add(atomic_read(&((struct sock *)tp)->sk_rmem_alloc),
+		   &meta_sk->sk_rmem_alloc);
+
+	mptcp_sub_inherit_sockopts(meta_sk, sk);
+	INIT_DELAYED_WORK(&tp->mptcp->work, mptcp_sub_close_wq);
+
+	/* As we successfully allocated the mptcp_tcp_sock, we have to
+	 * change the function-pointers here (for sk_destruct to work correctly)
+	 */
+	sk->sk_error_report = mptcp_sock_def_error_report;
+	sk->sk_data_ready = mptcp_data_ready;
+	sk->sk_write_space = mptcp_write_space;
+	sk->sk_state_change = mptcp_set_state;
+	sk->sk_destruct = mptcp_sock_destruct;
+
+	if (sk->sk_family == AF_INET)
+		mptcp_debug("%s: token %#x pi %d, src_addr:%pI4:%d dst_addr:%pI4:%d, cnt_subflows now %d\n",
+			    __func__ , mpcb->mptcp_loc_token,
+			    tp->mptcp->path_index,
+			    &((struct inet_sock *)tp)->inet_saddr,
+			    ntohs(((struct inet_sock *)tp)->inet_sport),
+			    &((struct inet_sock *)tp)->inet_daddr,
+			    ntohs(((struct inet_sock *)tp)->inet_dport),
+			    mpcb->cnt_subflows);
+	else
+		mptcp_debug("%s: token %#x pi %d, src_addr:%pI6:%d dst_addr:%pI6:%d, cnt_subflows now %d\n",
+			    __func__ , mpcb->mptcp_loc_token,
+			    tp->mptcp->path_index, &inet6_sk(sk)->saddr,
+			    ntohs(((struct inet_sock *)tp)->inet_sport),
+			    &inet6_sk(sk)->daddr,
+			    ntohs(((struct inet_sock *)tp)->inet_dport),
+			    mpcb->cnt_subflows);
+
+	return 0;
+}
+
+void mptcp_del_sock(struct sock *sk)
+{
+	struct tcp_sock *tp = tcp_sk(sk), *tp_prev;
+	struct mptcp_cb *mpcb;
+
+	if (!tp->mptcp || !tp->mptcp->attached)
+		return;
+
+	mpcb = tp->mpcb;
+	tp_prev = mpcb->connection_list;
+
+	mptcp_debug("%s: Removing subsock tok %#x pi:%d state %d is_meta? %d\n",
+		    __func__, mpcb->mptcp_loc_token, tp->mptcp->path_index,
+		    sk->sk_state, is_meta_sk(sk));
+
+	if (tp_prev == tp) {
+		mpcb->connection_list = tp->mptcp->next;
+	} else {
+		for (; tp_prev && tp_prev->mptcp->next; tp_prev = tp_prev->mptcp->next) {
+			if (tp_prev->mptcp->next == tp) {
+				tp_prev->mptcp->next = tp->mptcp->next;
+				break;
+			}
+		}
+	}
+	mpcb->cnt_subflows--;
+	if (tp->mptcp->establish_increased)
+		mpcb->cnt_established--;
+
+	tp->mptcp->next = NULL;
+	tp->mptcp->attached = 0;
+	mpcb->path_index_bits &= ~(1 << tp->mptcp->path_index);
+
+	if (!skb_queue_empty(&sk->sk_write_queue))
+		mptcp_reinject_data(sk, 0);
+
+	if (is_master_tp(tp))
+		mpcb->master_sk = NULL;
+	else if (tp->mptcp->pre_established)
+		sk_stop_timer(sk, &tp->mptcp->mptcp_ack_timer);
+
+	sk->sk_prot->release_cb(sk);
+
+	rcu_assign_pointer(inet_sk(sk)->inet_opt, NULL);
+}
+
+/* Updates the metasocket ULID/port data, based on the given sock.
+ * The argument sock must be the sock accessible to the application.
+ * In this function, we update the meta socket info, based on the changes
+ * in the application socket (bind, address allocation, ...)
+ */
+void mptcp_update_metasocket(struct sock *sk, struct sock *meta_sk)
+{
+	struct mptcp_cb *mpcb = tcp_sk(meta_sk)->mpcb;
+
+	switch (sk->sk_family) {
+#if IS_ENABLED(CONFIG_IPV6)
+	case AF_INET6:
+		/* If the socket is v4 mapped, we continue with v4 operations */
+		if (!mptcp_v6_is_v4_mapped(sk)) {
+			mpcb->locaddr6[0].addr = inet6_sk(sk)->saddr;
+			mpcb->locaddr6[0].id = 0;
+			mpcb->locaddr6[0].port = 0;
+			mpcb->locaddr6[0].low_prio = 0;
+			mpcb->loc6_bits |= 1;
+			mpcb->next_v6_index = 1;
+
+			mptcp_v6_add_raddress(mpcb,
+					      &inet6_sk(sk)->daddr, 0, 0);
+			mptcp_v6_set_init_addr_bit(mpcb, &inet6_sk(sk)->daddr);
+			break;
+		}
+#endif
+	case AF_INET:
+		mpcb->locaddr4[0].addr.s_addr = inet_sk(sk)->inet_saddr;
+		mpcb->locaddr4[0].id = 0;
+		mpcb->locaddr4[0].port = 0;
+		mpcb->locaddr4[0].low_prio = 0;
+		mpcb->loc4_bits |= 1;
+		mpcb->next_v4_index = 1;
+
+		mptcp_v4_add_raddress(mpcb,
+				      (struct in_addr *)&inet_sk(sk)->inet_daddr,
+				      0, 0);
+		mptcp_v4_set_init_addr_bit(mpcb, inet_sk(sk)->inet_daddr);
+		break;
+	}
+
+	mptcp_set_addresses(meta_sk);
+
+	switch (sk->sk_family) {
+	case AF_INET:
+		tcp_sk(sk)->mptcp->low_prio = mpcb->locaddr4[0].low_prio;
+		break;
+#if IS_ENABLED(CONFIG_IPV6)
+	case AF_INET6:
+		tcp_sk(sk)->mptcp->low_prio = mpcb->locaddr6[0].low_prio;
+		break;
+#endif
+	}
+
+	tcp_sk(sk)->mptcp->send_mp_prio = tcp_sk(sk)->mptcp->low_prio;
+}
+
+/* Clean up the receive buffer for full frames taken by the user,
+ * then send an ACK if necessary.  COPIED is the number of bytes
+ * tcp_recvmsg has given to the user so far, it speeds up the
+ * calculation of whether or not we must ACK for the sake of
+ * a window update.
+ */
+void mptcp_cleanup_rbuf(struct sock *meta_sk, int copied)
+{
+	struct tcp_sock *meta_tp = tcp_sk(meta_sk);
+	struct sock *sk;
+	__u32 rcv_window_now = 0;
+
+	if (copied > 0 && !(meta_sk->sk_shutdown & RCV_SHUTDOWN)) {
+		rcv_window_now = tcp_receive_window(meta_tp);
+
+		if (2 * rcv_window_now > meta_tp->window_clamp)
+			rcv_window_now = 0;
+	}
+
+	mptcp_for_each_sk(meta_tp->mpcb, sk) {
+		struct tcp_sock *tp = tcp_sk(sk);
+		const struct inet_connection_sock *icsk = inet_csk(sk);
+
+		if (!mptcp_sk_can_send_ack(sk))
+			continue;
+
+		if (!inet_csk_ack_scheduled(sk))
+			goto second_part;
+		/* Delayed ACKs frequently hit locked sockets during bulk
+		 * receive.
+		 */
+		if (icsk->icsk_ack.blocked ||
+		    /* Once-per-two-segments ACK was not sent by tcp_input.c */
+		    tp->rcv_nxt - tp->rcv_wup > icsk->icsk_ack.rcv_mss ||
+		    /* If this read emptied read buffer, we send ACK, if
+		     * connection is not bidirectional, user drained
+		     * receive buffer and there was a small segment
+		     * in queue.
+		     */
+		    (copied > 0 &&
+		     ((icsk->icsk_ack.pending & ICSK_ACK_PUSHED2) ||
+		      ((icsk->icsk_ack.pending & ICSK_ACK_PUSHED) &&
+		       !icsk->icsk_ack.pingpong)) &&
+		     !atomic_read(&meta_sk->sk_rmem_alloc))) {
+			tcp_send_ack(sk);
+			continue;
+		}
+
+second_part:
+		/* This here is the second part of tcp_cleanup_rbuf */
+		if (rcv_window_now) {
+			__u32 new_window = __tcp_select_window(sk);
+
+			/* Send ACK now, if this read freed lots of space
+			 * in our buffer. Certainly, new_window is new window.
+			 * We can advertise it now, if it is not less than
+			 * current one.
+			 * "Lots" means "at least twice" here.
+			 */
+			if (new_window && new_window >= 2 * rcv_window_now)
+				tcp_send_ack(sk);
+		}
+	}
+}
+
+static int mptcp_sub_send_fin(struct sock *sk)
+{
+	struct tcp_sock *tp = tcp_sk(sk);
+	struct sk_buff *skb = tcp_write_queue_tail(sk);
+	int mss_now;
+
+	/* Optimization, tack on the FIN if we have a queue of
+	 * unsent frames.  But be careful about outgoing SACKS
+	 * and IP options.
+	 */
+	mss_now = tcp_current_mss(sk);
+
+	if (tcp_send_head(sk) != NULL) {
+		TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_FIN;
+		TCP_SKB_CB(skb)->end_seq++;
+		tp->write_seq++;
+	} else {
+		skb = alloc_skb_fclone(MAX_TCP_HEADER, GFP_ATOMIC);
+		if (!skb)
+			return 1;
+
+		/* Reserve space for headers and prepare control bits. */
+		skb_reserve(skb, MAX_TCP_HEADER);
+		/* FIN eats a sequence byte, write_seq advanced by tcp_queue_skb(). */
+		tcp_init_nondata_skb(skb, tp->write_seq,
+				     TCPHDR_ACK | TCPHDR_FIN);
+		tcp_queue_skb(sk, skb);
+	}
+	__tcp_push_pending_frames(sk, mss_now, TCP_NAGLE_OFF);
+
+	return 0;
+}
+
+void mptcp_sub_close_wq(struct work_struct *work)
+{
+	struct mptcp_tcp_sock *mptcp = container_of(work, struct mptcp_tcp_sock, work.work);
+	struct tcp_sock *tp = mptcp->tp;
+	struct sock *sk = (struct sock *)tp;
+	struct sock *meta_sk = mptcp_meta_sk(sk);
+
+	mutex_lock(&tp->mpcb->mutex);
+	lock_sock_nested(meta_sk, SINGLE_DEPTH_NESTING);
+
+	if (sock_flag(sk, SOCK_DEAD))
+		goto exit;
+
+	/* We come from tcp_disconnect. We are sure that meta_sk is set */
+	if (!tp->mpc) {
+		tp->closing = 1;
+		sock_rps_reset_flow(sk);
+		tcp_close(sk, 0);
+		goto exit;
+	}
+
+	if (meta_sk->sk_shutdown == SHUTDOWN_MASK || sk->sk_state == TCP_CLOSE) {
+		tp->closing = 1;
+		sock_rps_reset_flow(sk);
+		tcp_close(sk, 0);
+	} else if (tcp_close_state(sk)) {
+		sk->sk_shutdown |= SEND_SHUTDOWN;
+		tcp_send_fin(sk);
+	}
+
+exit:
+	release_sock(meta_sk);
+	mutex_unlock(&tp->mpcb->mutex);
+	sock_put(sk);
+}
+
+void mptcp_sub_close(struct sock *sk, unsigned long delay)
+{
+	struct tcp_sock *tp = tcp_sk(sk);
+	struct delayed_work *work = &tcp_sk(sk)->mptcp->work;
+
+	/* We are already closing - e.g., call from sock_def_error_report upon
+	 * tcp_disconnect in tcp_close.
+	 */
+	if (tp->closing)
+		return;
+
+	/* Work already scheduled ? */
+	if (work_pending(&work->work)) {
+		/* Work present - who will be first ? */
+		if (jiffies + delay > work->timer.expires)
+			return;
+
+		/* Try canceling - if it fails, work will be executed soon */
+		if (!cancel_delayed_work(work))
+			return;
+		sock_put(sk);
+	}
+
+	if (!delay) {
+		unsigned char old_state = sk->sk_state;
+
+		/* If we are in user-context we can directly do the closing
+		 * procedure. No need to schedule a work-queue.
+		 */
+		if (!in_softirq()) {
+			if (sock_flag(sk, SOCK_DEAD))
+				return;
+
+			if (!tp->mpc) {
+				tp->closing = 1;
+				sock_rps_reset_flow(sk);
+				tcp_close(sk, 0);
+				return;
+			}
+
+			if (mptcp_meta_sk(sk)->sk_shutdown == SHUTDOWN_MASK ||
+			    sk->sk_state == TCP_CLOSE) {
+				tp->closing = 1;
+				sock_rps_reset_flow(sk);
+				tcp_close(sk, 0);
+			} else if (tcp_close_state(sk)) {
+				sk->sk_shutdown |= SEND_SHUTDOWN;
+				tcp_send_fin(sk);
+			}
+
+			return;
+		}
+
+		/* We directly send the FIN. Because it may take so a long time,
+		 * untile the work-queue will get scheduled...
+		 *
+		 * If mptcp_sub_send_fin returns 1, it failed and thus we reset
+		 * the old state so that tcp_close will finally send the fin
+		 * in user-context.
+		 */
+		if (!sk->sk_err && old_state != TCP_CLOSE &&
+		    tcp_close_state(sk) && mptcp_sub_send_fin(sk)) {
+			if (old_state == TCP_ESTABLISHED)
+				TCP_INC_STATS(sock_net(sk), TCP_MIB_CURRESTAB);
+			sk->sk_state = old_state;
+		}
+	}
+
+	sock_hold(sk);
+	queue_delayed_work(mptcp_wq, work, delay);
+}
+
+/* Update the mpcb send window, based on the contributions
+ * of each subflow
+ */
+void mptcp_update_sndbuf(struct mptcp_cb *mpcb)
+{
+	struct sock *meta_sk = mpcb->meta_sk, *sk;
+	int new_sndbuf = 0;
+	mptcp_for_each_sk(mpcb, sk) {
+		if (!mptcp_sk_can_send(sk))
+			continue;
+
+		new_sndbuf += sk->sk_sndbuf;
+
+		if (new_sndbuf > sysctl_tcp_wmem[2] || new_sndbuf < 0) {
+			new_sndbuf = sysctl_tcp_wmem[2];
+			break;
+		}
+	}
+	meta_sk->sk_sndbuf = max(min(new_sndbuf, sysctl_tcp_wmem[2]), meta_sk->sk_sndbuf);
+}
+
+void mptcp_close(struct sock *meta_sk, long timeout)
+{
+	struct tcp_sock *meta_tp = tcp_sk(meta_sk);
+	struct sock *sk_it, *tmpsk;
+	struct mptcp_cb *mpcb = meta_tp->mpcb;
+	struct sk_buff *skb;
+	int data_was_unread = 0;
+	int state;
+
+	mptcp_debug("%s: Close of meta_sk with tok %#x\n",
+		    __func__, mpcb->mptcp_loc_token);
+
+	mutex_lock(&mpcb->mutex);
+	lock_sock(meta_sk);
+
+	if (meta_tp->inside_tk_table) {
+		/* Detach the mpcb from the token hashtable */
+		mptcp_hash_remove_bh(meta_tp);
+		reqsk_queue_destroy(&inet_csk(meta_sk)->icsk_accept_queue);
+	}
+
+	meta_sk->sk_shutdown = SHUTDOWN_MASK;
+	/* We need to flush the recv. buffs.  We do this only on the
+	 * descriptor close, not protocol-sourced closes, because the
+	 * reader process may not have drained the data yet!
+	 */
+	while ((skb = __skb_dequeue(&meta_sk->sk_receive_queue)) != NULL) {
+		u32 len = TCP_SKB_CB(skb)->end_seq - TCP_SKB_CB(skb)->seq -
+			  tcp_hdr(skb)->fin;
+		data_was_unread += len;
+		__kfree_skb(skb);
+	}
+
+	sk_mem_reclaim(meta_sk);
+
+	/* If socket has been already reset (e.g. in tcp_reset()) - kill it. */
+	if (meta_sk->sk_state == TCP_CLOSE) {
+		mptcp_for_each_sk_safe(mpcb, sk_it, tmpsk)
+			mptcp_sub_close(sk_it, 0);
+		goto adjudge_to_death;
+	}
+
+	if (data_was_unread) {
+		/* Unread data was tossed, zap the connection. */
+		NET_INC_STATS_USER(sock_net(meta_sk), LINUX_MIB_TCPABORTONCLOSE);
+		tcp_set_state(meta_sk, TCP_CLOSE);
+		tcp_send_active_reset(meta_sk, meta_sk->sk_allocation);
+	} else if (sock_flag(meta_sk, SOCK_LINGER) && !meta_sk->sk_lingertime) {
+		/* Check zero linger _after_ checking for unread data. */
+		meta_sk->sk_prot->disconnect(meta_sk, 0);
+		NET_INC_STATS_USER(sock_net(meta_sk), LINUX_MIB_TCPABORTONDATA);
+	} else if (tcp_close_state(meta_sk)) {
+		mptcp_send_fin(meta_sk);
+	} else if (meta_tp->snd_una == meta_tp->write_seq) {
+		/* The DATA_FIN has been sent and acknowledged
+		 * (e.g., by sk_shutdown). Close all the other subflows
+		 */
+		mptcp_for_each_sk_safe(mpcb, sk_it, tmpsk) {
+			unsigned long delay = 0;
+			/* If we are the passive closer, don't trigger
+			 * subflow-fin until the subflow has been finned
+			 * by the peer. - thus we add a delay
+			 */
+			if (mpcb->passive_close &&
+			    sk_it->sk_state == TCP_ESTABLISHED)
+				delay = inet_csk(sk_it)->icsk_rto << 3;
+
+			mptcp_sub_close(sk_it, delay);
+		}
+	}
+
+	sk_stream_wait_close(meta_sk, timeout);
+
+adjudge_to_death:
+	state = meta_sk->sk_state;
+	sock_hold(meta_sk);
+	sock_orphan(meta_sk);
+
+	/* socket will be freed after mptcp_close - we have to prevent
+	 * access from the subflows.
+	 */
+	mptcp_for_each_sk(mpcb, sk_it) {
+		/* Similar to sock_orphan, but we don't set it DEAD, because
+		 * the callbacks are still set and must be called.
+		 */
+		write_lock_bh(&sk_it->sk_callback_lock);
+		sk_set_socket(sk_it, NULL);
+		sk_it->sk_wq  = NULL;
+		write_unlock_bh(&sk_it->sk_callback_lock);
+	}
+
+	/* It is the last release_sock in its life. It will remove backlog. */
+	release_sock(meta_sk);
+
+	/* Now socket is owned by kernel and we acquire BH lock
+	 * to finish close. No need to check for user refs.
+	 */
+	local_bh_disable();
+	bh_lock_sock(meta_sk);
+	WARN_ON(sock_owned_by_user(meta_sk));
+
+	percpu_counter_inc(meta_sk->sk_prot->orphan_count);
+
+	/* Have we already been destroyed by a softirq or backlog? */
+	if (state != TCP_CLOSE && meta_sk->sk_state == TCP_CLOSE)
+		goto out;
+
+	/*	This is a (useful) BSD violating of the RFC. There is a
+	 *	problem with TCP as specified in that the other end could
+	 *	keep a socket open forever with no application left this end.
+	 *	We use a 3 minute timeout (about the same as BSD) then kill
+	 *	our end. If they send after that then tough - BUT: long enough
+	 *	that we won't make the old 4*rto = almost no time - whoops
+	 *	reset mistake.
+	 *
+	 *	Nope, it was not mistake. It is really desired behaviour
+	 *	f.e. on http servers, when such sockets are useless, but
+	 *	consume significant resources. Let's do it with special
+	 *	linger2	option.					--ANK
+	 */
+
+	if (meta_sk->sk_state == TCP_FIN_WAIT2) {
+		if (meta_tp->linger2 < 0) {
+			tcp_set_state(meta_sk, TCP_CLOSE);
+			tcp_send_active_reset(meta_sk, GFP_ATOMIC);
+			NET_INC_STATS_BH(sock_net(meta_sk),
+					 LINUX_MIB_TCPABORTONLINGER);
+		} else {
+			const int tmo = tcp_fin_time(meta_sk);
+
+			if (tmo > TCP_TIMEWAIT_LEN) {
+				inet_csk_reset_keepalive_timer(meta_sk,
+							       tmo - TCP_TIMEWAIT_LEN);
+			} else {
+				tcp_time_wait(meta_sk, TCP_FIN_WAIT2, tmo);
+				goto out;
+			}
+		}
+	}
+	if (meta_sk->sk_state != TCP_CLOSE) {
+		sk_mem_reclaim(meta_sk);
+		if (tcp_too_many_orphans(meta_sk, 0)) {
+			if (net_ratelimit())
+				pr_info("MPTCP: too many of orphaned sockets\n");
+			tcp_set_state(meta_sk, TCP_CLOSE);
+			tcp_send_active_reset(meta_sk, GFP_ATOMIC);
+			NET_INC_STATS_BH(sock_net(meta_sk),
+					 LINUX_MIB_TCPABORTONMEMORY);
+		}
+	}
+
+
+	if (meta_sk->sk_state == TCP_CLOSE)
+		inet_csk_destroy_sock(meta_sk);
+	/* Otherwise, socket is reprieved until protocol close. */
+
+out:
+	bh_unlock_sock(meta_sk);
+	local_bh_enable();
+	mutex_unlock(&mpcb->mutex);
+	sock_put(meta_sk); /* Taken by sock_hold */
+}
+
+/* Returns 1 if we should enable MPTCP for that socket. */
+int mptcp_doit(struct sock *sk)
+{
+	/* Do not allow MPTCP enabling if the MPTCP initialization failed */
+	if (mptcp_init_failed)
+		return 0;
+
+	/* Socket may already be established (e.g., called from tcp_recvmsg) */
+	if (tcp_sk(sk)->mpc || tcp_sk(sk)->request_mptcp)
+		return 1;
+
+	if (!sysctl_mptcp_enabled)
+		return 0;
+
+	/* Don't do mptcp over loopback or local addresses */
+	if (sk->sk_family == AF_INET &&
+	    (ipv4_is_loopback(inet_sk(sk)->inet_daddr) ||
+	     ipv4_is_loopback(inet_sk(sk)->inet_saddr)))
+		return 0;
+	if (sk->sk_family == AF_INET6 &&
+	    (ipv6_addr_loopback(&inet6_sk(sk)->daddr) ||
+	     ipv6_addr_loopback(&inet6_sk(sk)->saddr)))
+		return 0;
+	if (mptcp_v6_is_v4_mapped(sk) &&
+	    ipv4_is_loopback(inet_sk(sk)->inet_saddr))
+		return 0;
+
+	return 1;
+}
+
+int mptcp_create_master_sk(struct sock *meta_sk, __u64 remote_key, u32 window)
+{
+	struct tcp_sock *master_tp;
+	struct sock *master_sk;
+
+	if (mptcp_alloc_mpcb(meta_sk, remote_key, window))
+		goto err_alloc_mpcb;
+
+	master_sk = tcp_sk(meta_sk)->mpcb->master_sk;
+	master_tp = tcp_sk(master_sk);
+
+	if (mptcp_add_sock(meta_sk, master_sk, 0, GFP_ATOMIC))
+		goto err_add_sock;
+
+	if (__inet_inherit_port(meta_sk, master_sk) < 0)
+		goto err_add_sock;
+
+	meta_sk->sk_prot->unhash(meta_sk);
+
+	if (master_sk->sk_family == AF_INET || mptcp_v6_is_v4_mapped(master_sk))
+		__inet_hash_nolisten(master_sk, NULL);
+#if IS_ENABLED(CONFIG_IPV6)
+	else
+		__inet6_hash(master_sk, NULL);
+#endif
+
+	master_tp->mptcp->init_rcv_wnd = master_tp->rcv_wnd;
+
+	return 0;
+
+err_add_sock:
+	mptcp_fallback_meta_sk(meta_sk);
+
+	inet_csk_prepare_forced_close(master_sk);
+	tcp_done(master_sk);
+	inet_csk_prepare_forced_close(meta_sk);
+	tcp_done(meta_sk);
+
+err_alloc_mpcb:
+	return -ENOBUFS;
+}
+
+int mptcp_check_req_master(struct sock *sk, struct sock *child,
+			   struct request_sock *req,
+			   struct request_sock **prev,
+			   struct mptcp_options_received *mopt)
+{
+	struct tcp_sock *child_tp = tcp_sk(child);
+	struct sock *meta_sk = child;
+	struct mptcp_cb *mpcb;
+	struct mptcp_request_sock *mtreq;
+
+	if (!tcp_rsk(req)->saw_mpc)
+		return 1;
+
+	/* Just set this values to pass them to mptcp_alloc_mpcb */
+	mtreq = mptcp_rsk(req);
+	child_tp->mptcp_loc_key = mtreq->mptcp_loc_key;
+	child_tp->mptcp_loc_token = mtreq->mptcp_loc_token;
+
+	if (mptcp_create_master_sk(meta_sk, mtreq->mptcp_rem_key,
+				   child_tp->snd_wnd))
+		return -ENOBUFS;
+
+	child = tcp_sk(child)->mpcb->master_sk;
+	child_tp = tcp_sk(child);
+	mpcb = child_tp->mpcb;
+
+	child_tp->mptcp->snt_isn = tcp_rsk(req)->snt_isn;
+	child_tp->mptcp->rcv_isn = tcp_rsk(req)->rcv_isn;
+
+	mpcb->dss_csum = mtreq->dss_csum;
+	mpcb->server_side = 1;
+
+	/* Will be moved to ESTABLISHED by  tcp_rcv_state_process() */
+	mptcp_update_metasocket(child, meta_sk);
+
+	/* Needs to be done here additionally, because when accepting a
+	 * new connection we pass by __reqsk_free and not reqsk_free.
+	 */
+	mptcp_reqsk_remove_tk(req);
+
+	 /* Hold when creating the meta-sk in tcp_vX_syn_recv_sock. */
+	sock_put(meta_sk);
+
+	inet_csk_reqsk_queue_unlink(sk, req, prev);
+	inet_csk_reqsk_queue_removed(sk, req);
+	inet_csk_reqsk_queue_add(sk, req, meta_sk);
+
+	return 0;
+}
+
+struct sock *mptcp_check_req_child(struct sock *meta_sk, struct sock *child,
+				   struct request_sock *req,
+				   struct request_sock **prev,
+				   struct mptcp_options_received *mopt)
+{
+	struct tcp_sock *child_tp = tcp_sk(child);
+	struct mptcp_request_sock *mtreq = mptcp_rsk(req);
+	struct mptcp_cb *mpcb = mtreq->mpcb;
+	u8 hash_mac_check[20];
+
+	child_tp->inside_tk_table = 0;
+
+	if (!mopt->join_ack)
+		goto teardown;
+
+	mptcp_hmac_sha1((u8 *)&mpcb->mptcp_rem_key,
+			(u8 *)&mpcb->mptcp_loc_key,
+			(u8 *)&mtreq->mptcp_rem_nonce,
+			(u8 *)&mtreq->mptcp_loc_nonce,
+			(u32 *)hash_mac_check);
+
+	if (memcmp(hash_mac_check, (char *)&mopt->mptcp_recv_mac, 20))
+		goto teardown;
+
+	/* Point it to the same struct socket and wq as the meta_sk */
+	sk_set_socket(child, meta_sk->sk_socket);
+	child->sk_wq = meta_sk->sk_wq;
+
+	if (mptcp_add_sock(meta_sk, child, mtreq->rem_id, GFP_ATOMIC)) {
+		child_tp->mpc = 0; /* Has been inherited, but now
+				    * child_tp->mptcp is NULL
+				    */
+		/* TODO when we support acking the third ack for new subflows,
+		 * we should silently discard this third ack, by returning NULL.
+		 *
+		 * Maybe, at the retransmission we will have enough memory to
+		 * fully add the socket to the meta-sk.
+		 */
+		goto teardown;
+	}
+
+	/* The child is a clone of the meta socket, we must now reset
+	 * some of the fields
+	 */
+	child_tp->mptcp->rcv_low_prio = mtreq->low_prio;
+
+	/* We should allow proper increase of the snd/rcv-buffers. Thus, we
+	 * use the original values instead of the bloated up ones from the
+	 * clone.
+	 */
+	child->sk_sndbuf = mpcb->orig_sk_sndbuf;
+	child->sk_rcvbuf = mpcb->orig_sk_rcvbuf;
+
+	child_tp->mptcp->slave_sk = 1;
+	child_tp->mptcp->snt_isn = tcp_rsk(req)->snt_isn;
+	child_tp->mptcp->rcv_isn = tcp_rsk(req)->rcv_isn;
+	child_tp->mptcp->init_rcv_wnd = req->rcv_wnd;
+
+	child_tp->tsq_flags = 0;
+
+	/* Subflows do not use the accept queue, as they
+	 * are attached immediately to the mpcb.
+	 */
+	inet_csk_reqsk_queue_drop(meta_sk, req, prev);
+	return child;
+
+teardown:
+	/* Drop this request - sock creation failed. */
+	inet_csk_reqsk_queue_drop(meta_sk, req, prev);
+	inet_csk_prepare_forced_close(child);
+	tcp_done(child);
+	return meta_sk;
+}
+
+int mptcp_time_wait(struct sock *sk, struct tcp_timewait_sock *tw)
+{
+	struct mptcp_tw *mptw;
+	struct tcp_sock *tp = tcp_sk(sk);
+	struct mptcp_cb *mpcb = tp->mpcb;
+
+	/* Alloc MPTCP-tw-sock */
+	mptw = kmem_cache_alloc(mptcp_tw_cache, GFP_ATOMIC);
+	if (!mptw)
+		return -ENOBUFS;
+
+	atomic_inc(&mpcb->refcnt);
+
+	tw->mptcp_tw = mptw;
+	mptw->loc_key = mpcb->mptcp_loc_key;
+	mptw->meta_tw = mpcb->in_time_wait;
+	if (mptw->meta_tw) {
+		mptw->rcv_nxt = mptcp_get_rcv_nxt_64(mptcp_meta_tp(tp));
+		if (mpcb->mptw_state != TCP_TIME_WAIT)
+			mptw->rcv_nxt++;
+	}
+	rcu_assign_pointer(mptw->mpcb, mpcb);
+
+	spin_lock(&mpcb->tw_lock);
+	list_add_rcu(&mptw->list, &tp->mpcb->tw_list);
+	mptw->in_list = 1;
+	spin_unlock(&mpcb->tw_lock);
+
+	return 0;
+}
+
+void mptcp_twsk_destructor(struct tcp_timewait_sock *tw)
+{
+	struct mptcp_cb *mpcb;
+
+	rcu_read_lock();
+	mpcb = rcu_dereference(tw->mptcp_tw->mpcb);
+
+	/* If we are still holding a ref to the mpcb, we have to remove ourself
+	 * from the list and drop the ref properly.
+	 */
+	if (mpcb && atomic_inc_not_zero(&mpcb->refcnt)) {
+		spin_lock(&mpcb->tw_lock);
+		if (tw->mptcp_tw->in_list) {
+			list_del_rcu(&tw->mptcp_tw->list);
+			tw->mptcp_tw->in_list = 0;
+		}
+		spin_unlock(&mpcb->tw_lock);
+
+		/* Twice, because we increased it above */
+		mptcp_mpcb_put(mpcb);
+		mptcp_mpcb_put(mpcb);
+	}
+
+	rcu_read_unlock();
+
+	kmem_cache_free(mptcp_tw_cache, tw->mptcp_tw);
+}
+
+/* Updates the rcv_nxt of the time-wait-socks and allows them to ack a
+ * data-fin.
+ */
+void mptcp_update_tw_socks(const struct tcp_sock *tp, int state)
+{
+	struct mptcp_tw *mptw;
+
+	/* Used for sockets that go into tw after the meta
+	 * (see mptcp_time_wait())
+	 */
+	tp->mpcb->in_time_wait = 1;
+	tp->mpcb->mptw_state = state;
+
+	/* Update the time-wait-sock's information */
+	rcu_read_lock_bh();
+	list_for_each_entry_rcu(mptw, &tp->mpcb->tw_list, list) {
+		mptw->meta_tw = 1;
+		mptw->rcv_nxt = mptcp_get_rcv_nxt_64(tp);
+
+		/* We want to ack a DATA_FIN, but are yet in FIN_WAIT_2 -
+		 * pretend as if the DATA_FIN has already reached us, that way
+		 * the checks in tcp_timewait_state_process will be good as the
+		 * DATA_FIN comes in.
+		 */
+		if (state != TCP_TIME_WAIT)
+			mptw->rcv_nxt++;
+	}
+	rcu_read_unlock_bh();
+}
+
+struct workqueue_struct *mptcp_wq;
+
+/* General initialization of mptcp */
+void __init mptcp_init(void)
+{
+#ifdef CONFIG_SYSCTL
+	struct ctl_table_header *mptcp_sysctl;
+#endif
+
+	mptcp_sock_cache = kmem_cache_create("mptcp_sock",
+					     sizeof(struct mptcp_tcp_sock),
+					     0, SLAB_HWCACHE_ALIGN,
+					     NULL);
+	if (!mptcp_sock_cache)
+		goto mptcp_sock_cache_failed;
+
+	mptcp_cb_cache = kmem_cache_create("mptcp_cb", sizeof(struct mptcp_cb),
+					   0, SLAB_DESTROY_BY_RCU|SLAB_HWCACHE_ALIGN,
+					   NULL);
+	if (!mptcp_cb_cache)
+		goto mptcp_cb_cache_failed;
+
+	mptcp_tw_cache = kmem_cache_create("mptcp_tw", sizeof(struct mptcp_tw),
+					   0, SLAB_DESTROY_BY_RCU|SLAB_HWCACHE_ALIGN,
+					   NULL);
+	if (!mptcp_tw_cache)
+		goto mptcp_tw_cache_failed;
+
+	get_random_bytes(mptcp_secret, sizeof(mptcp_secret));
+
+	mptcp_wq = alloc_workqueue("mptcp_wq", WQ_UNBOUND | WQ_MEM_RECLAIM, 8);
+	if (!mptcp_wq)
+		goto alloc_workqueue_failed;
+
+	if (mptcp_pm_init())
+		goto mptcp_pm_failed;
+
+#ifdef CONFIG_SYSCTL
+	mptcp_sysctl = register_net_sysctl(&init_net, "net/mptcp", mptcp_table);
+	if (!mptcp_sysctl)
+		goto register_sysctl_failed;
+#endif
+
+	pr_info("MPTCP: Stable release v0.87.2");
+
+	mptcp_init_failed = false;
+
+	return;
+
+#ifdef CONFIG_SYSCTL
+register_sysctl_failed:
+	mptcp_pm_undo();
+#endif
+mptcp_pm_failed:
+	destroy_workqueue(mptcp_wq);
+alloc_workqueue_failed:
+	kmem_cache_destroy(mptcp_tw_cache);
+mptcp_tw_cache_failed:
+	kmem_cache_destroy(mptcp_cb_cache);
+mptcp_cb_cache_failed:
+	kmem_cache_destroy(mptcp_sock_cache);
+mptcp_sock_cache_failed:
+	mptcp_init_failed = true;
+}
diff -Naur a/net/mptcp/mptcp_input.c b/net/mptcp/mptcp_input.c
--- a/net/mptcp/mptcp_input.c	1970-01-01 01:00:00.000000000 +0100
+++ b/net/mptcp/mptcp_input.c	2013-10-06 18:26:04.506866022 +0200
@@ -0,0 +1,1904 @@
+/*
+ *	MPTCP implementation - Sending side
+ *
+ *	Initial Design & Implementation:
+ *	Sébastien Barré <[e-mail]>
+ *
+ *	Current Maintainer & Author:
+ *	Christoph Paasch <[e-mail]>
+ *
+ *	Additional authors:
+ *	Jaakko Korkeaniemi <[e-mail]>
+ *	Gregory Detal <[e-mail]>
+ *	Fabien Duchêne <[e-mail]>
+ *	Andreas Seelinger <[e-mail]>
+ *	Lavkesh Lahngir <[e-mail]>
+ *	Andreas Ripke <[e-mail]>
+ *	Vlad Dogaru <[e-mail]>
+ *	Octavian Purdila <[e-mail]>
+ *	John Ronan <[e-mail]>
+ *	Catalin Nicutar <[e-mail]>
+ *	Brandon Heller <[e-mail]>
+ *
+ *
+ *	This program is free software; you can redistribute it and/or
+ *      modify it under the terms of the GNU General Public License
+ *      as published by the Free Software Foundation; either version
+ *      2 of the License, or (at your option) any later version.
+ */
+
+#include <asm/unaligned.h>
+
+#include <net/mptcp.h>
+#include <net/mptcp_v4.h>
+#include <net/mptcp_v6.h>
+
+#include <linux/kconfig.h>
+
+static inline void mptcp_become_fully_estab(struct sock *sk)
+{
+	tcp_sk(sk)->mptcp->fully_established = 1;
+
+	if (is_master_tp(tcp_sk(sk)))
+		mptcp_create_subflows(mptcp_meta_sk(sk));
+}
+
+/* Similar to tcp_tso_acked without any memory accounting */
+static inline int mptcp_tso_acked_reinject(struct sock *sk, struct sk_buff *skb)
+{
+	struct tcp_sock *tp = tcp_sk(sk);
+	u32 packets_acked, len;
+
+	BUG_ON(!after(TCP_SKB_CB(skb)->end_seq, tp->snd_una));
+
+	packets_acked = tcp_skb_pcount(skb);
+
+	if (skb_cloned(skb) && pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
+		return 0;
+
+	len = tp->snd_una - TCP_SKB_CB(skb)->seq;
+	__pskb_trim_head(skb, len);
+
+	TCP_SKB_CB(skb)->seq += len;
+	skb->ip_summed = CHECKSUM_PARTIAL;
+	skb->truesize	     -= len;
+
+	/* Any change of skb->len requires recalculation of tso factor. */
+	if (tcp_skb_pcount(skb) > 1)
+		tcp_set_skb_tso_segs(sk, skb, tcp_skb_mss(skb));
+	packets_acked -= tcp_skb_pcount(skb);
+
+	if (packets_acked) {
+		BUG_ON(tcp_skb_pcount(skb) == 0);
+		BUG_ON(!before(TCP_SKB_CB(skb)->seq, TCP_SKB_CB(skb)->end_seq));
+	}
+
+	return packets_acked;
+}
+
+/**
+ * Cleans the meta-socket retransmission queue and the reinject-queue.
+ * @sk must be the metasocket.
+ */
+static void mptcp_clean_rtx_queue(struct sock *meta_sk, u32 prior_snd_una)
+{
+	struct sk_buff *skb, *tmp;
+	struct tcp_sock *meta_tp = tcp_sk(meta_sk);
+	struct mptcp_cb *mpcb = meta_tp->mpcb;
+	bool acked = false;
+	u32 acked_pcount;
+
+	while ((skb = tcp_write_queue_head(meta_sk)) &&
+	       skb != tcp_send_head(meta_sk)) {
+		bool fully_acked = true;
+
+		if (before(meta_tp->snd_una, TCP_SKB_CB(skb)->end_seq)) {
+			if (tcp_skb_pcount(skb) == 1 ||
+			    !after(meta_tp->snd_una, TCP_SKB_CB(skb)->seq))
+				break;
+
+			acked_pcount = tcp_tso_acked(meta_sk, skb);
+			if (!acked_pcount)
+				break;
+
+			fully_acked = false;
+		} else {
+			acked_pcount = tcp_skb_pcount(skb);
+		}
+
+		acked = true;
+		meta_tp->packets_out -= acked_pcount;
+		meta_tp->retrans_stamp = 0;
+
+		if (!fully_acked)
+			break;
+
+		tcp_unlink_write_queue(skb, meta_sk);
+
+		if (mptcp_is_data_fin(skb)) {
+			struct sock *sk_it;
+
+			/* DATA_FIN has been acknowledged - now we can close
+			 * the subflows
+			 */
+			mptcp_for_each_sk(mpcb, sk_it) {
+				unsigned long delay = 0;
+
+				/* If we are the passive closer, don't trigger
+				 * subflow-fin until the subflow has been finned
+				 * by the peer - thus we add a delay.
+				 */
+				if (mpcb->passive_close &&
+				    sk_it->sk_state == TCP_ESTABLISHED)
+					delay = inet_csk(sk_it)->icsk_rto << 3;
+
+				mptcp_sub_close(sk_it, delay);
+			}
+		}
+		sk_wmem_free_skb(meta_sk, skb);
+	}
+	/* Remove acknowledged data from the reinject queue */
+	skb_queue_walk_safe(&mpcb->reinject_queue, skb, tmp) {
+		if (before(meta_tp->snd_una, TCP_SKB_CB(skb)->end_seq)) {
+			if (tcp_skb_pcount(skb) == 1 ||
+			    !after(meta_tp->snd_una, TCP_SKB_CB(skb)->seq))
+				break;
+
+			mptcp_tso_acked_reinject(meta_sk, skb);
+			break;
+		}
+
+		__skb_unlink(skb, &mpcb->reinject_queue);
+		__kfree_skb(skb);
+	}
+
+	if (likely(between(meta_tp->snd_up, prior_snd_una, meta_tp->snd_una)))
+		meta_tp->snd_up = meta_tp->snd_una;
+
+	if (acked) {
+		tcp_rearm_rto(meta_sk);
+		/* Normally this is done in tcp_try_undo_loss - but MPTCP
+		 * does not call this function.
+		 */
+		inet_csk(meta_sk)->icsk_retransmits = 0;
+	}
+}
+
+/* Inspired by tcp_rcv_state_process */
+static int mptcp_rcv_state_process(struct sock *meta_sk, struct sock *sk,
+				   const struct sk_buff *skb, u32 data_seq,
+				   u16 data_len)
+{
+	struct tcp_sock *meta_tp = tcp_sk(meta_sk), *tp = tcp_sk(sk);
+	struct tcphdr *th = tcp_hdr(skb);
+
+	/* State-machine handling if FIN has been enqueued and he has
+	 * been acked (snd_una == write_seq) - it's important that this
+	 * here is after sk_wmem_free_skb because otherwise
+	 * sk_forward_alloc is wrong upon inet_csk_destroy_sock()
+	 */
+	switch (meta_sk->sk_state) {
+	case TCP_FIN_WAIT1:
+		if (meta_tp->snd_una == meta_tp->write_seq) {
+			struct dst_entry *dst = __sk_dst_get(meta_sk);
+
+			tcp_set_state(meta_sk, TCP_FIN_WAIT2);
+			meta_sk->sk_shutdown |= SEND_SHUTDOWN;
+
+			dst = __sk_dst_get(sk);
+			if (dst)
+				dst_confirm(dst);
+
+			if (!sock_flag(meta_sk, SOCK_DEAD)) {
+				/* Wake up lingering close() */
+				meta_sk->sk_state_change(meta_sk);
+			} else {
+				int tmo;
+
+				if (meta_tp->linger2 < 0 ||
+				    (data_len &&
+				     after(data_seq + data_len - (mptcp_is_data_fin2(skb, tp) ? 1 : 0),
+					   meta_tp->rcv_nxt))) {
+					mptcp_send_active_reset(meta_sk, GFP_ATOMIC);
+					tcp_done(meta_sk);
+					NET_INC_STATS_BH(sock_net(meta_sk), LINUX_MIB_TCPABORTONDATA);
+					return 1;
+				}
+
+				tmo = tcp_fin_time(meta_sk);
+				if (tmo > TCP_TIMEWAIT_LEN) {
+					inet_csk_reset_keepalive_timer(meta_sk, tmo - TCP_TIMEWAIT_LEN);
+				} else if (mptcp_is_data_fin2(skb, tp) ||
+					   sock_owned_by_user(meta_sk)) {
+					/* Bad case. We could lose such FIN otherwise.
+					 * It is not a big problem, but it looks confusing
+					 * and not so rare event. We still can lose it now,
+					 * if it spins in bh_lock_sock(), but it is really
+					 * marginal case.
+					 */
+					inet_csk_reset_keepalive_timer(meta_sk, tmo);
+				} else {
+					tcp_time_wait(meta_sk, TCP_FIN_WAIT2, tmo);
+				}
+			}
+		}
+		break;
+	case TCP_CLOSING:
+	case TCP_LAST_ACK:
+		if (meta_tp->snd_una == meta_tp->write_seq) {
+			tcp_done(meta_sk);
+			return 1;
+		}
+		break;
+	}
+
+	/* step 7: process the segment text */
+	switch (meta_sk->sk_state) {
+	case TCP_FIN_WAIT1:
+	case TCP_FIN_WAIT2:
+		/* RFC 793 says to queue data in these states,
+		 * RFC 1122 says we MUST send a reset.
+		 * BSD 4.4 also does reset.
+		 */
+		if (meta_sk->sk_shutdown & RCV_SHUTDOWN) {
+			if (TCP_SKB_CB(skb)->end_seq != TCP_SKB_CB(skb)->seq &&
+			    after(TCP_SKB_CB(skb)->end_seq - th->fin, tp->rcv_nxt) &&
+			    !mptcp_is_data_fin2(skb, tp)) {
+				NET_INC_STATS_BH(sock_net(meta_sk), LINUX_MIB_TCPABORTONDATA);
+
+				mptcp_send_active_reset(meta_sk, GFP_ATOMIC);
+			}
+		}
+		break;
+	}
+
+	return 0;
+}
+
+/**
+ * @return:
+ *  i) 1: Everything's fine.
+ *  ii) -1: A reset has been sent on the subflow - csum-failure
+ *  iii) 0: csum-failure but no reset sent, because it's the last subflow.
+ *	 Last packet should not be destroyed by the caller because it has
+ *	 been done here.
+ */
+static int mptcp_verif_dss_csum(struct sock *sk)
+{
+	struct tcp_sock *tp = tcp_sk(sk);
+	struct sk_buff *tmp, *tmp1, *last = NULL;
+	__wsum csum_tcp = 0; /* cumulative checksum of pld + mptcp-header */
+	int ans = 1, overflowed = 0, offset = 0, dss_csum_added = 0;
+	int iter = 0;
+
+	skb_queue_walk_safe(&sk->sk_receive_queue, tmp, tmp1) {
+		unsigned int csum_len;
+
+		if (before(tp->mptcp->map_subseq + tp->mptcp->map_data_len, TCP_SKB_CB(tmp)->end_seq))
+			/* Mapping ends in the middle of the packet -
+			 * csum only these bytes
+			 */
+			csum_len = tp->mptcp->map_subseq + tp->mptcp->map_data_len - TCP_SKB_CB(tmp)->seq;
+		else
+			csum_len = tmp->len;
+
+		offset = 0;
+		if (overflowed) {
+			char first_word[4];
+			first_word[0] = 0;
+			first_word[1] = 0;
+			first_word[2] = 0;
+			first_word[3] = *(tmp->data);
+			csum_tcp = csum_partial(first_word, 4, csum_tcp);
+			offset = 1;
+			csum_len--;
+			overflowed = 0;
+		}
+
+		csum_tcp = skb_checksum(tmp, offset, csum_len, csum_tcp);
+
+		/* Was it on an odd-length? Then we have to merge the next byte
+		 * correctly (see above)
+		 */
+		if (csum_len != (csum_len & (~1)))
+			overflowed = 1;
+
+		if (mptcp_is_data_seq(tmp) && !dss_csum_added) {
+			__be32 data_seq = htonl((u32)(tp->mptcp->map_data_seq >> 32));
+
+			/* If a 64-bit dss is present, we increase the offset
+			 * by 4 bytes, as the high-order 64-bits will be added
+			 * in the final csum_partial-call.
+			 */
+			u32 offset = skb_transport_offset(tmp) +
+				     TCP_SKB_CB(tmp)->dss_off;
+			if (TCP_SKB_CB(tmp)->mptcp_flags & MPTCPHDR_SEQ64_SET)
+				offset += 4;
+
+			csum_tcp = skb_checksum(tmp, offset,
+						MPTCP_SUB_LEN_SEQ_CSUM,
+						csum_tcp);
+
+			csum_tcp = csum_partial(&data_seq,
+						sizeof(data_seq), csum_tcp);
+
+			dss_csum_added = 1; /* Just do it once */
+		}
+		last = tmp;
+		iter++;
+
+		if (!skb_queue_is_last(&sk->sk_receive_queue, tmp) &&
+		    !before(TCP_SKB_CB(tmp1)->seq,
+			    tp->mptcp->map_subseq + tp->mptcp->map_data_len))
+			break;
+	}
+
+	/* Now, checksum must be 0 */
+	if (unlikely(csum_fold(csum_tcp))) {
+		pr_err("%s csum is wrong: %#x data_seq %u dss_csum_added %d overflowed %d iterations %d\n",
+			    __func__, csum_fold(csum_tcp),
+			    TCP_SKB_CB(last)->seq, dss_csum_added, overflowed,
+			    iter);
+
+		tp->mptcp->send_mp_fail = 1;
+
+		/* map_data_seq is the data-seq number of the
+		 * mapping we are currently checking
+		 */
+		tp->mpcb->csum_cutoff_seq = tp->mptcp->map_data_seq;
+
+		if (tp->mpcb->cnt_subflows > 1) {
+			mptcp_send_reset(sk);
+			ans = -1;
+		} else {
+			tp->mpcb->send_infinite_mapping = 1;
+
+			/* Need to purge the rcv-queue as it's no more valid */
+			while ((tmp = __skb_dequeue(&sk->sk_receive_queue)) != NULL) {
+				tp->copied_seq = TCP_SKB_CB(tmp)->end_seq;
+				kfree_skb(tmp);
+			}
+
+			ans = 0;
+		}
+	}
+
+	return ans;
+}
+
+static inline void mptcp_prepare_skb(struct sk_buff *skb, struct sk_buff *next,
+				     struct sock *sk)
+{
+	struct tcp_sock *tp = tcp_sk(sk);
+	struct tcp_skb_cb *tcb = TCP_SKB_CB(skb);
+	/* Adapt data-seq's to the packet itself. We kinda transform the
+	 * dss-mapping to a per-packet granularity. This is necessary to
+	 * correctly handle overlapping mappings coming from different
+	 * subflows. Otherwise it would be a complete mess.
+	 */
+	tcb->seq = ((u32)tp->mptcp->map_data_seq) + tcb->seq - tp->mptcp->map_subseq;
+	tcb->end_seq = tcb->seq + skb->len;
+
+	/* If cur is the last one in the rcv-queue (or the last one for this
+	 * mapping), and data_fin is enqueued, the end_data_seq is +1.
+	 */
+	if (skb_queue_is_last(&sk->sk_receive_queue, skb) ||
+	    after(TCP_SKB_CB(next)->end_seq, tp->mptcp->map_subseq + tp->mptcp->map_data_len)) {
+		tcb->end_seq += tp->mptcp->map_data_fin;
+
+		/* We manually set the fin-flag if it is a data-fin. For easy
+		 * processing in tcp_recvmsg.
+		 */
+		if (mptcp_is_data_fin2(skb, tp))
+			tcp_hdr(skb)->fin = 1;
+		else
+			tcp_hdr(skb)->fin = 0;
+	} else {
+		/* We may have a subflow-fin with data but without data-fin */
+		tcp_hdr(skb)->fin = 0;
+	}
+}
+
+/**
+ * @return: 1 if the segment has been eaten and can be suppressed,
+ *          otherwise 0.
+ */
+static inline int mptcp_direct_copy(struct sk_buff *skb, struct sock *meta_sk)
+{
+	struct tcp_sock *meta_tp = tcp_sk(meta_sk);
+	int chunk = min_t(unsigned int, skb->len, meta_tp->ucopy.len);
+	int eaten = 0;
+
+	__set_current_state(TASK_RUNNING);
+
+	local_bh_enable();
+	if (!skb_copy_datagram_iovec(skb, 0, meta_tp->ucopy.iov, chunk)) {
+		meta_tp->ucopy.len -= chunk;
+		meta_tp->copied_seq += chunk;
+		eaten = (chunk == skb->len);
+		tcp_rcv_space_adjust(meta_sk);
+	}
+	local_bh_disable();
+	return eaten;
+}
+
+static inline void mptcp_reset_mapping(struct tcp_sock *tp)
+{
+	tp->mptcp->map_data_len = 0;
+	tp->mptcp->map_data_seq = 0;
+	tp->mptcp->map_subseq = 0;
+	tp->mptcp->map_data_fin = 0;
+	tp->mptcp->mapping_present = 0;
+}
+
+/* The DSS-mapping received on the sk only covers the second half of the skb
+ * (cut at seq). We trim the head from the skb.
+ * Data will be freed upon kfree().
+ *
+ * Inspired by tcp_trim_head().
+ */
+static void mptcp_skb_trim_head(struct sk_buff *skb, struct sock *sk, u32 seq)
+{
+	int len = seq - TCP_SKB_CB(skb)->seq;
+	u32 new_seq = TCP_SKB_CB(skb)->seq + len;
+
+	if (len < skb_headlen(skb))
+		__skb_pull(skb, len);
+	else
+		__pskb_trim_head(skb, len - skb_headlen(skb));
+
+	TCP_SKB_CB(skb)->seq = htonl(new_seq);
+
+	skb->truesize -= len;
+	atomic_sub(len, &sk->sk_rmem_alloc);
+	sk_mem_uncharge(sk, len);
+}
+
+/* The DSS-mapping received on the sk only covers the first half of the skb
+ * (cut at seq). We create a second skb (@return), and queue it in the rcv-queue
+ * as further packets may resolve the mapping of the second half of data.
+ *
+ * Inspired by tcp_fragment().
+ */
+static int mptcp_skb_split_tail(struct sk_buff *skb, struct sock *sk, u32 seq)
+{
+	struct sk_buff *buff;
+	int nsize;
+	int nlen, len;
+
+	len = seq - TCP_SKB_CB(skb)->seq;
+	nsize = skb_headlen(skb) - len + tcp_sk(sk)->tcp_header_len;
+	if (nsize < 0)
+		nsize = 0;
+
+	/* Get a new skb... force flag on. */
+	buff = alloc_skb(nsize, GFP_ATOMIC);
+	if (buff == NULL)
+		return -ENOMEM;
+
+	skb_reserve(buff, tcp_sk(sk)->tcp_header_len);
+	skb_reset_transport_header(buff);
+
+	tcp_hdr(buff)->fin = tcp_hdr(skb)->fin;
+	tcp_hdr(skb)->fin = 0;
+
+	/* We absolutly need to call skb_set_owner_r before refreshing the
+	 * truesize of buff, otherwise the moved data will account twice.
+	 */
+	skb_set_owner_r(buff, sk);
+	nlen = skb->len - len - nsize;
+	buff->truesize += nlen;
+	skb->truesize -= nlen;
+
+	/* Correct the sequence numbers. */
+	TCP_SKB_CB(buff)->seq = TCP_SKB_CB(skb)->seq + len;
+	TCP_SKB_CB(buff)->end_seq = TCP_SKB_CB(skb)->end_seq;
+	TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(buff)->seq;
+
+	skb_split(skb, buff, len);
+
+	__skb_queue_after(&sk->sk_receive_queue, skb, buff);
+
+	return 0;
+}
+
+/* @return: 0  everything is fine. Just continue processing
+ *	    1  subflow is broken stop everything
+ *	    -1 this packet was broken - continue with the next one.
+ */
+static int mptcp_prevalidate_skb(struct sock *sk, struct sk_buff *skb)
+{
+	struct tcp_sock *tp = tcp_sk(sk);
+
+	/* If we are in infinite mode, the subflow-fin is in fact a data-fin. */
+	if (!skb->len && tcp_hdr(skb)->fin && !mptcp_is_data_fin(skb) &&
+	    !tp->mpcb->infinite_mapping_rcv) {
+		/* Remove a pure subflow-fin from the queue and increase
+		 * copied_seq.
+		 */
+		tp->copied_seq = TCP_SKB_CB(skb)->end_seq;
+		__skb_unlink(skb, &sk->sk_receive_queue);
+		__kfree_skb(skb);
+		return -1;
+	}
+
+	/* If we are not yet fully established and do not know the mapping for
+	 * this segment, this path has to fallback to infinite or be torn down.
+	 */
+	if (!tp->mptcp->fully_established && !mptcp_is_data_seq(skb) &&
+	    !tp->mptcp->mapping_present && !tp->mpcb->infinite_mapping_rcv) {
+		pr_err("%s %#x will fallback - pi %d from %pS, seq %u\n",
+		       __func__, tp->mpcb->mptcp_loc_token,
+		       tp->mptcp->path_index, __builtin_return_address(0),
+		       TCP_SKB_CB(skb)->seq);
+
+		if (!is_master_tp(tp)) {
+			mptcp_send_reset(sk);
+			return 1;
+		}
+
+		tp->mpcb->infinite_mapping_snd = 1;
+		tp->mpcb->infinite_mapping_rcv = 1;
+		tp->mptcp->fully_established = 1;
+	}
+
+	/* Receiver-side becomes fully established when a whole rcv-window has
+	 * been received without the need to fallback due to the previous
+	 * condition. */
+	if (!tp->mptcp->fully_established) {
+		tp->mptcp->init_rcv_wnd -= skb->len;
+		if (tp->mptcp->init_rcv_wnd < 0)
+			mptcp_become_fully_estab(sk);
+	}
+
+	return 0;
+}
+
+/* @return: 0  everything is fine. Just continue processing
+ *	    1  subflow is broken stop everything
+ *	    -1 this packet was broken - continue with the next one.
+ */
+static int mptcp_detect_mapping(struct sock *sk, struct sk_buff *skb)
+{
+	struct tcp_sock *tp = tcp_sk(sk), *meta_tp = mptcp_meta_tp(tp);
+	struct mptcp_cb *mpcb = tp->mpcb;
+	struct tcp_skb_cb *tcb = TCP_SKB_CB(skb);
+	u32 *ptr;
+	u32 data_seq, sub_seq, data_len, tcp_end_seq;
+
+	/* If we are in infinite-mapping-mode, the subflow is guaranteed to be
+	 * in-order at the data-level. Thus data-seq-numbers can be inferred
+	 * from what is expected at the data-level.
+	 */
+	if (mpcb->infinite_mapping_rcv) {
+		tp->mptcp->map_data_seq = mptcp_get_rcv_nxt_64(meta_tp);
+		tp->mptcp->map_subseq = tcb->seq;
+		tp->mptcp->map_data_len = skb->len;
+		tp->mptcp->map_data_fin = tcp_hdr(skb)->fin;
+		tp->mptcp->mapping_present = 1;
+		return 0;
+	}
+
+	/* No mapping here? Exit - it is either already set or still on its way */
+	if (!mptcp_is_data_seq(skb)) {
+		/* Too many packets without a mapping - this subflow is broken */
+		if (!tp->mptcp->mapping_present &&
+		    tp->rcv_nxt - tp->copied_seq > 65536) {
+			mptcp_send_reset(sk);
+			return 1;
+		}
+
+		return 0;
+	}
+
+	ptr = mptcp_skb_set_data_seq(skb, &data_seq, mpcb);
+	ptr++;
+	sub_seq = get_unaligned_be32(ptr) + tp->mptcp->rcv_isn;
+	ptr++;
+	data_len = get_unaligned_be16(ptr);
+
+	/* If it's an empty skb with DATA_FIN, sub_seq must get fixed.
+	 * The draft sets it to 0, but we really would like to have the
+	 * real value, to have an easy handling afterwards here in this
+	 * function.
+	 */
+	if (mptcp_is_data_fin(skb) && skb->len == 0)
+		sub_seq = TCP_SKB_CB(skb)->seq;
+
+	/* If there is already a mapping - we check if it maps with the current
+	 * one. If not - we reset.
+	 */
+	if (tp->mptcp->mapping_present &&
+	    (data_seq != (u32)tp->mptcp->map_data_seq ||
+	     sub_seq != tp->mptcp->map_subseq ||
+	     data_len != tp->mptcp->map_data_len + tp->mptcp->map_data_fin ||
+	     mptcp_is_data_fin(skb) != tp->mptcp->map_data_fin)) {
+		/* Mapping in packet is different from what we want */
+		pr_err("%s Mappings do not match!\n", __func__);
+		pr_err("%s dseq %u mdseq %u, sseq %u msseq %u dlen %u mdlen %u dfin %d mdfin %d\n",
+		       __func__, data_seq, (u32)tp->mptcp->map_data_seq,
+		       sub_seq, tp->mptcp->map_subseq, data_len,
+		       tp->mptcp->map_data_len, mptcp_is_data_fin(skb),
+		       tp->mptcp->map_data_fin);
+		mptcp_send_reset(sk);
+		return 1;
+	}
+
+	/* If the previous check was good, the current mapping is valid and we exit. */
+	if (tp->mptcp->mapping_present)
+		return 0;
+
+	/* Mapping not yet set on this subflow - we set it here! */
+
+	if (!data_len) {
+		mpcb->infinite_mapping_rcv = 1;
+		tp->mptcp->fully_established = 1;
+		/* We need to repeat mp_fail's until the sender felt
+		 * back to infinite-mapping - here we stop repeating it.
+		 */
+		tp->mptcp->send_mp_fail = 0;
+
+		/* We have to fixup data_len - it must be the same as skb->len */
+		data_len = skb->len + (mptcp_is_data_fin(skb) ? 1 : 0);
+		sub_seq = tcb->seq;
+
+		/* TODO kill all other subflows than this one */
+		/* data_seq and so on are set correctly */
+
+		/* At this point, the meta-ofo-queue has to be emptied,
+		 * as the following data is guaranteed to be in-order at
+		 * the data and subflow-level
+		 */
+		mptcp_purge_ofo_queue(meta_tp);
+	}
+
+	/* We are sending mp-fail's and thus are in fallback mode.
+	 * Ignore packets which do not announce the fallback and still
+	 * want to provide a mapping.
+	 */
+	if (tp->mptcp->send_mp_fail) {
+		tp->copied_seq = TCP_SKB_CB(skb)->end_seq;
+		__skb_unlink(skb, &sk->sk_receive_queue);
+		__kfree_skb(skb);
+		return -1;
+	}
+
+	/* FIN increased the mapping-length by 1 */
+	if (mptcp_is_data_fin(skb))
+		data_len--;
+
+	/* Subflow-sequences of packet must be
+	 * (at least partially) be part of the DSS-mapping's
+	 * subflow-sequence-space.
+	 *
+	 * Basically the mapping is not valid, if either of the
+	 * following conditions is true:
+	 *
+	 * 1. It's not a data_fin and
+	 *    MPTCP-sub_seq >= TCP-end_seq
+	 *
+	 * 2. It's a data_fin and TCP-end_seq > TCP-seq and
+	 *    MPTCP-sub_seq >= TCP-end_seq
+	 *
+	 * The previous two can be merged into:
+	 *    TCP-end_seq > TCP-seq and MPTCP-sub_seq >= TCP-end_seq
+	 *    Because if it's not a data-fin, TCP-end_seq > TCP-seq
+	 *
+	 * 3. It's a data_fin and skb->len == 0 and
+	 *    MPTCP-sub_seq > TCP-end_seq
+	 *
+	 * 4. It's not a data_fin and TCP-end_seq > TCP-seq and
+	 *    MPTCP-sub_seq + MPTCP-data_len <= TCP-seq
+	 *
+	 * 5. MPTCP-sub_seq is prior to what we already copied (copied_seq)
+	 */
+
+	/* subflow-fin is not part of the mapping - ignore it here ! */
+	tcp_end_seq = tcb->end_seq - tcp_hdr(skb)->fin;
+	if ((!before(sub_seq, tcb->end_seq) && after(tcp_end_seq, tcb->seq)) ||
+	    (mptcp_is_data_fin(skb) && skb->len == 0 && after(sub_seq, tcb->end_seq)) ||
+	    (!after(sub_seq + data_len, tcb->seq) && after(tcp_end_seq, tcb->seq)) ||
+	    before(sub_seq, tp->copied_seq)) {
+		/* Subflow-sequences of packet is different from what is in the
+		 * packet's dss-mapping. The peer is misbehaving - reset
+		 */
+		pr_err("%s Packet's mapping does not map to the DSS sub_seq %u "
+		       "end_seq %u, tcp_end_seq %u seq %u dfin %u len %u data_len %u"
+		       "copied_seq %u\n", __func__, sub_seq, tcb->end_seq, tcp_end_seq, tcb->seq, mptcp_is_data_fin(skb),
+		       skb->len, data_len, tp->copied_seq);
+		mptcp_send_reset(sk);
+		return 1;
+	}
+
+	/* Does the DSS had 64-bit seqnum's ? */
+	if (!(tcb->mptcp_flags & MPTCPHDR_SEQ64_SET)) {
+		/* Wrapped around? */
+		if (unlikely(after(data_seq, meta_tp->rcv_nxt) && data_seq < meta_tp->rcv_nxt)) {
+			tp->mptcp->map_data_seq = mptcp_get_data_seq_64(mpcb, !mpcb->rcv_hiseq_index, data_seq);
+		} else {
+			/* Else, access the default high-order bits */
+			tp->mptcp->map_data_seq = mptcp_get_data_seq_64(mpcb, mpcb->rcv_hiseq_index, data_seq);
+		}
+	} else {
+		tp->mptcp->map_data_seq = mptcp_get_data_seq_64(mpcb, (tcb->mptcp_flags & MPTCPHDR_SEQ64_INDEX) ? 1 : 0, data_seq);
+
+		if (unlikely(tcb->mptcp_flags & MPTCPHDR_SEQ64_OFO)) {
+			/* We make sure that the data_seq is invalid.
+			 * It will be dropped later.
+			 */
+			tp->mptcp->map_data_seq += 0xFFFFFFFF;
+			tp->mptcp->map_data_seq += 0xFFFFFFFF;
+		}
+	}
+
+	tp->mptcp->map_data_len = data_len;
+	tp->mptcp->map_subseq = sub_seq;
+	tp->mptcp->map_data_fin = mptcp_is_data_fin(skb) ? 1 : 0;
+	tp->mptcp->mapping_present = 1;
+
+	return 0;
+}
+
+/* Similar to tcp_sequence(...) */
+static inline int mptcp_sequence(const struct tcp_sock *meta_tp,
+				 u64 data_seq, u64 end_data_seq)
+{
+	struct mptcp_cb *mpcb = meta_tp->mpcb;
+	u64 rcv_wup64;
+
+	/* Wrap-around? */
+	if (meta_tp->rcv_wup > meta_tp->rcv_nxt) {
+		rcv_wup64 = ((u64)(mpcb->rcv_high_order[mpcb->rcv_hiseq_index] - 1) << 32) |
+				meta_tp->rcv_wup;
+	} else {
+		rcv_wup64 = mptcp_get_data_seq_64(mpcb, mpcb->rcv_hiseq_index,
+						  meta_tp->rcv_wup);
+	}
+
+	return	!before64(end_data_seq, rcv_wup64) &&
+		!after64(data_seq, mptcp_get_rcv_nxt_64(meta_tp) + tcp_receive_window(meta_tp));
+}
+
+/* @return: 0  everything is fine. Just continue processing
+ *	    -1 this packet was broken - continue with the next one.
+ */
+static int mptcp_validate_mapping(struct sock *sk, struct sk_buff *skb)
+{
+	struct tcp_sock *tp = tcp_sk(sk);
+	struct sk_buff *tmp, *tmp1;
+	u32 tcp_end_seq;
+
+	if (!tp->mptcp->mapping_present)
+		return 0;
+
+	/* either, the new skb gave us the mapping and the first segment
+	 * in the sub-rcv-queue has to be trimmed ...
+	 */
+	tmp = skb_peek(&sk->sk_receive_queue);
+	if (before(TCP_SKB_CB(tmp)->seq, tp->mptcp->map_subseq) &&
+	    after(TCP_SKB_CB(tmp)->end_seq, tp->mptcp->map_subseq))
+		mptcp_skb_trim_head(tmp, sk, tp->mptcp->map_subseq);
+
+	/* ... or the new skb (tail) has to be split at the end. */
+	tcp_end_seq = TCP_SKB_CB(skb)->end_seq - (tcp_hdr(skb)->fin ? 1 : 0);
+	if (after(tcp_end_seq, tp->mptcp->map_subseq + tp->mptcp->map_data_len)) {
+		u32 seq = tp->mptcp->map_subseq + tp->mptcp->map_data_len;
+		if (mptcp_skb_split_tail(skb, sk, seq)) { /* Allocation failed */
+			/* TODO : maybe handle this here better.
+			 * We now just force meta-retransmission.
+			 */
+			tp->copied_seq = TCP_SKB_CB(skb)->end_seq;
+			__skb_unlink(skb, &sk->sk_receive_queue);
+			__kfree_skb(skb);
+			return -1;
+		}
+	}
+
+	/* Now, remove old sk_buff's from the receive-queue.
+	 * This may happen if the mapping has been lost for these segments and
+	 * the next mapping has already been received.
+	 */
+	if (tp->mptcp->mapping_present &&
+	    before(TCP_SKB_CB(skb_peek(&sk->sk_receive_queue))->seq, tp->mptcp->map_subseq)) {
+		skb_queue_walk_safe(&sk->sk_receive_queue, tmp1, tmp) {
+			if (!before(TCP_SKB_CB(tmp1)->seq, tp->mptcp->map_subseq))
+				break;
+
+			tp->copied_seq = TCP_SKB_CB(tmp1)->end_seq;
+			__skb_unlink(tmp1, &sk->sk_receive_queue);
+
+			/* Impossible that we could free skb here, because his
+			 * mapping is known to be valid from previous checks
+			 */
+			__kfree_skb(tmp1);
+		}
+	}
+
+	return 0;
+}
+
+/* @return: 0  everything is fine. Just continue processing
+ *	    1  subflow is broken stop everything
+ *	    -1 this mapping has been put in the meta-receive-queue
+ *	    -2 this mapping has been eaten by the application
+ */
+static int mptcp_queue_skb(struct sock *sk)
+{
+	struct tcp_sock *tp = tcp_sk(sk), *meta_tp = mptcp_meta_tp(tp);
+	struct sock *meta_sk = mptcp_meta_sk(sk);
+	struct mptcp_cb *mpcb = tp->mpcb;
+	struct sk_buff *tmp, *tmp1;
+	u64 rcv_nxt64 = mptcp_get_rcv_nxt_64(meta_tp);
+	bool data_queued = false;
+
+	/* Have we not yet received the full mapping? */
+	if (!tp->mptcp->mapping_present ||
+	    before(tp->rcv_nxt, tp->mptcp->map_subseq + tp->mptcp->map_data_len))
+		return 0;
+
+	/* Is this an overlapping mapping? rcv_nxt >= end_data_seq
+	 * OR
+	 * This mapping is out of window
+	 */
+	if (!before64(rcv_nxt64, tp->mptcp->map_data_seq + tp->mptcp->map_data_len + tp->mptcp->map_data_fin) ||
+	    !mptcp_sequence(meta_tp, tp->mptcp->map_data_seq,
+			    tp->mptcp->map_data_seq + tp->mptcp->map_data_len + tp->mptcp->map_data_fin)) {
+		skb_queue_walk_safe(&sk->sk_receive_queue, tmp1, tmp) {
+			__skb_unlink(tmp1, &sk->sk_receive_queue);
+			tp->copied_seq = TCP_SKB_CB(tmp1)->end_seq;
+			__kfree_skb(tmp1);
+
+			if (!skb_queue_empty(&sk->sk_receive_queue) &&
+			    !before(TCP_SKB_CB(tmp)->seq,
+				    tp->mptcp->map_subseq + tp->mptcp->map_data_len))
+				break;
+		}
+
+		mptcp_reset_mapping(tp);
+
+		return -1;
+	}
+
+	/* Record it, because we want to send our data_fin on the same path */
+	if (tp->mptcp->map_data_fin) {
+		mpcb->dfin_path_index = tp->mptcp->path_index;
+		mpcb->dfin_combined = !!(sk->sk_shutdown & RCV_SHUTDOWN);
+	}
+
+	/* Verify the checksum */
+	if (mpcb->dss_csum && !mpcb->infinite_mapping_rcv) {
+		int ret = mptcp_verif_dss_csum(sk);
+
+		if (ret <= 0) {
+			mptcp_reset_mapping(tp);
+			return 1;
+		}
+	}
+
+	if (before64(rcv_nxt64, tp->mptcp->map_data_seq)) {
+		/* Seg's have to go to the meta-ofo-queue */
+		skb_queue_walk_safe(&sk->sk_receive_queue, tmp1, tmp) {
+			tp->copied_seq = TCP_SKB_CB(tmp1)->end_seq;
+			mptcp_prepare_skb(tmp1, tmp, sk);
+			__skb_unlink(tmp1, &sk->sk_receive_queue);
+			/* MUST be done here, because fragstolen may be true later.
+			 * Then, kfree_skb_partial will not account the memory.
+			 */
+			skb_orphan(tmp1);
+
+			if (!mpcb->in_time_wait) /* In time-wait, do not receive data */
+				mptcp_add_meta_ofo_queue(meta_sk, tmp1, sk);
+			else
+				__kfree_skb(tmp1);
+
+			if (!skb_queue_empty(&sk->sk_receive_queue) &&
+			    !before(TCP_SKB_CB(tmp)->seq,
+				    tp->mptcp->map_subseq + tp->mptcp->map_data_len))
+				break;
+
+		}
+	} else {
+		/* Ready for the meta-rcv-queue */
+		skb_queue_walk_safe(&sk->sk_receive_queue, tmp1, tmp) {
+			int eaten = 0;
+			int copied_early = 0;
+			bool fragstolen = false;
+			u32 old_rcv_nxt = meta_tp->rcv_nxt;
+
+			tp->copied_seq = TCP_SKB_CB(tmp1)->end_seq;
+			mptcp_prepare_skb(tmp1, tmp, sk);
+			__skb_unlink(tmp1, &sk->sk_receive_queue);
+			/* MUST be done here, because fragstolen may be true.
+			 * Then, kfree_skb_partial will not account the memory.
+			 */
+			skb_orphan(tmp1);
+
+			/* This segment has already been received */
+			if (!after(TCP_SKB_CB(tmp1)->end_seq, meta_tp->rcv_nxt)) {
+				__kfree_skb(tmp1);
+				goto next;
+			}
+
+#ifdef CONFIG_NET_DMA
+			if (TCP_SKB_CB(tmp1)->seq == meta_tp->rcv_nxt  &&
+			    meta_tp->ucopy.task == current &&
+			    meta_tp->copied_seq == meta_tp->rcv_nxt &&
+			    tmp1->len <= meta_tp->ucopy.len &&
+			    sock_owned_by_user(meta_sk) &&
+			    tcp_dma_try_early_copy(meta_sk, tmp1, 0)) {
+				copied_early = 1;
+				eaten = 1;
+			}
+#endif
+
+			/* Is direct copy possible ? */
+			if (TCP_SKB_CB(tmp1)->seq == meta_tp->rcv_nxt &&
+			    meta_tp->ucopy.task == current &&
+			    meta_tp->copied_seq == meta_tp->rcv_nxt &&
+			    meta_tp->ucopy.len && sock_owned_by_user(meta_sk) &&
+			    !copied_early)
+				eaten = mptcp_direct_copy(tmp1, meta_sk);
+
+			if (mpcb->in_time_wait) /* In time-wait, do not receive data */
+				eaten = 1;
+
+			if (!eaten)
+				eaten = tcp_queue_rcv(meta_sk, tmp1, 0, &fragstolen);
+
+			meta_tp->rcv_nxt = TCP_SKB_CB(tmp1)->end_seq;
+			mptcp_check_rcvseq_wrap(meta_tp, old_rcv_nxt);
+
+			if (copied_early)
+				tcp_cleanup_rbuf(meta_sk, tmp1->len);
+
+			if (tcp_hdr(tmp1)->fin && !mpcb->in_time_wait)
+				mptcp_fin(meta_sk);
+
+			/* Check if this fills a gap in the ofo queue */
+			if (!skb_queue_empty(&meta_tp->out_of_order_queue))
+				mptcp_ofo_queue(meta_sk);
+
+#ifdef CONFIG_NET_DMA
+			if (copied_early)
+				__skb_queue_tail(&meta_sk->sk_async_wait_queue,
+						 tmp1);
+			else
+#endif
+			if (eaten)
+				kfree_skb_partial(tmp1, fragstolen);
+
+			data_queued = true;
+next:
+			if (!skb_queue_empty(&sk->sk_receive_queue) &&
+			    !before(TCP_SKB_CB(tmp)->seq,
+				    tp->mptcp->map_subseq + tp->mptcp->map_data_len))
+				break;
+		}
+	}
+
+	inet_csk(meta_sk)->icsk_ack.lrcvtime = tcp_time_stamp;
+	tp->mptcp->last_data_seq = tp->mptcp->map_data_seq;
+	mptcp_reset_mapping(tp);
+
+	return data_queued ? -1 : -2;
+}
+
+void mptcp_data_ready(struct sock *sk, int bytes)
+{
+	struct sock *meta_sk = mptcp_meta_sk(sk);
+	struct sk_buff *skb, *tmp;
+	int queued = 0;
+
+	/* If the meta is already closed, there is no point in pushing data */
+	if (meta_sk->sk_state == TCP_CLOSE && !tcp_sk(sk)->mpcb->in_time_wait) {
+		skb_queue_purge(&sk->sk_receive_queue);
+		tcp_sk(sk)->copied_seq = tcp_sk(sk)->rcv_nxt;
+		goto exit;
+	}
+
+restart:
+	/* Iterate over all segments, detect their mapping (if we don't have
+	 * one yet), validate them and push everything one level higher.
+	 */
+	skb_queue_walk_safe(&sk->sk_receive_queue, skb, tmp) {
+		int ret;
+		/* Pre-validation - e.g., early fallback */
+		ret = mptcp_prevalidate_skb(sk, skb);
+		if (ret < 0)
+			goto restart;
+		else if (ret > 0)
+			break;
+
+		/* Set the current mapping */
+		ret = mptcp_detect_mapping(sk, skb);
+		if (ret < 0)
+			goto restart;
+		else if (ret > 0)
+			break;
+
+		/* Validation */
+		if (mptcp_validate_mapping(sk, skb) < 0)
+			goto restart;
+
+		/* Push a level higher */
+		ret = mptcp_queue_skb(sk);
+		if (ret < 0) {
+			if (ret == -1)
+				queued = ret;
+			goto restart;
+		} else if (ret == 0) {
+			continue;
+		} else { /* ret == 1 */
+			break;
+		}
+	}
+
+exit:
+	if (tcp_sk(sk)->close_it) {
+		tcp_send_ack(sk);
+		tcp_time_wait(sk, TCP_TIME_WAIT, 0);
+	}
+
+	if (queued == -1 && !sock_flag(meta_sk, SOCK_DEAD))
+		meta_sk->sk_data_ready(meta_sk, 0);
+}
+
+/**
+ * Equivalent of tcp_fin() for MPTCP
+ * Can be called only when the FIN is validly part
+ * of the data seqnum space. Not before when we get holes.
+ */
+void mptcp_fin(struct sock *meta_sk)
+{
+	struct sock *sk = NULL, *sk_it;
+	struct tcp_sock *meta_tp = tcp_sk(meta_sk);
+	struct mptcp_cb *mpcb = meta_tp->mpcb;
+
+	mptcp_for_each_sk(mpcb, sk_it) {
+		if (tcp_sk(sk_it)->mptcp->path_index == mpcb->dfin_path_index) {
+			sk = sk_it;
+			break;
+		}
+	}
+
+	if (!sk || sk->sk_state == TCP_CLOSE)
+		sk = mptcp_select_ack_sock(meta_sk, 0);
+
+	inet_csk_schedule_ack(sk);
+
+	meta_sk->sk_shutdown |= RCV_SHUTDOWN;
+	sock_set_flag(meta_sk, SOCK_DONE);
+
+	switch (meta_sk->sk_state) {
+	case TCP_SYN_RECV:
+	case TCP_ESTABLISHED:
+		/* Move to CLOSE_WAIT */
+		tcp_set_state(meta_sk, TCP_CLOSE_WAIT);
+		inet_csk(sk)->icsk_ack.pingpong = 1;
+		break;
+
+	case TCP_CLOSE_WAIT:
+	case TCP_CLOSING:
+		/* Received a retransmission of the FIN, do
+		 * nothing.
+		 */
+		break;
+	case TCP_LAST_ACK:
+		/* RFC793: Remain in the LAST-ACK state. */
+		break;
+
+	case TCP_FIN_WAIT1:
+		/* This case occurs when a simultaneous close
+		 * happens, we must ack the received FIN and
+		 * enter the CLOSING state.
+		 */
+		tcp_send_ack(sk);
+		tcp_set_state(meta_sk, TCP_CLOSING);
+		break;
+	case TCP_FIN_WAIT2:
+		/* Received a FIN -- send ACK and enter TIME_WAIT. */
+		tcp_send_ack(sk);
+		tcp_time_wait(meta_sk, TCP_TIME_WAIT, 0);
+		break;
+	default:
+		/* Only TCP_LISTEN and TCP_CLOSE are left, in these
+		 * cases we should never reach this piece of code.
+		 */
+		pr_err("%s: Impossible, meta_sk->sk_state=%d\n", __func__,
+		       meta_sk->sk_state);
+		break;
+	}
+
+	/* It _is_ possible, that we have something out-of-order _after_ FIN.
+	 * Probably, we should reset in this case. For now drop them.
+	 */
+	mptcp_purge_ofo_queue(meta_tp);
+	sk_mem_reclaim(meta_sk);
+
+	if (!sock_flag(meta_sk, SOCK_DEAD)) {
+		meta_sk->sk_state_change(meta_sk);
+
+		/* Do not send POLL_HUP for half duplex close. */
+		if (meta_sk->sk_shutdown == SHUTDOWN_MASK ||
+		    meta_sk->sk_state == TCP_CLOSE)
+			sk_wake_async(meta_sk, SOCK_WAKE_WAITD, POLL_HUP);
+		else
+			sk_wake_async(meta_sk, SOCK_WAKE_WAITD, POLL_IN);
+	}
+
+	return;
+}
+
+static void mptcp_xmit_retransmit_queue(struct sock *meta_sk)
+{
+	struct tcp_sock *meta_tp = tcp_sk(meta_sk);
+	struct sk_buff *skb;
+
+	if (!meta_tp->packets_out)
+		return;
+
+	tcp_for_write_queue(skb, meta_sk) {
+		if (skb == tcp_send_head(meta_sk))
+			break;
+
+		if (mptcp_retransmit_skb(meta_sk, skb))
+			return;
+
+		if (skb == tcp_write_queue_head(meta_sk))
+			inet_csk_reset_xmit_timer(meta_sk, ICSK_TIME_RETRANS,
+						  inet_csk(meta_sk)->icsk_rto,
+						  TCP_RTO_MAX);
+	}
+}
+
+/* Handle the DATA_ACK */
+static void mptcp_data_ack(struct sock *sk, const struct sk_buff *skb)
+{
+	struct sock *meta_sk = mptcp_meta_sk(sk);
+	struct tcp_sock *meta_tp = tcp_sk(meta_sk), *tp = tcp_sk(sk);
+	struct tcp_skb_cb *tcb = TCP_SKB_CB(skb);
+	u32 prior_snd_una = meta_tp->snd_una;
+	int prior_packets;
+	u32 nwin, data_ack, data_seq;
+	u16 data_len = 0;
+
+	/* A valid packet came in - subflow is operational again */
+	tp->pf = 0;
+
+	/* Even if there is no data-ack, we stop retransmitting.
+	 * Except if this is a SYN/ACK. Then it is just a retransmission
+	 */
+	if (tp->mptcp->pre_established && !tcp_hdr(skb)->syn) {
+		tp->mptcp->pre_established = 0;
+		sk_stop_timer(sk, &tp->mptcp->mptcp_ack_timer);
+	}
+
+	/* If we are in infinite mapping mode, rx_opt.data_ack has been
+	 * set by mptcp_clean_rtx_infinite.
+	 */
+	if (!(tcb->mptcp_flags & MPTCPHDR_ACK) && !tp->mpcb->infinite_mapping_snd)
+		goto exit;
+
+	data_ack = tp->mptcp->rx_opt.data_ack;
+
+	if (unlikely(!tp->mptcp->fully_established) &&
+	    (data_ack != meta_tp->mptcp->snt_isn ||
+	    tp->mptcp->snt_isn + 1 != TCP_SKB_CB(skb)->ack_seq))
+		/* As soon as data has been data-acked,
+		 * or a subflow-data-ack (not acking syn - thus snt_isn + 1)
+		 * includes a data-ack, we are fully established
+		 */
+		mptcp_become_fully_estab(sk);
+
+	/* Get the data_seq */
+	if (mptcp_is_data_seq(skb)) {
+		data_seq = tp->mptcp->rx_opt.data_seq;
+		data_len = tp->mptcp->rx_opt.data_len;
+	} else {
+		data_seq = meta_tp->snd_wl1;
+	}
+
+	/* If the ack is older than previous acks
+	 * then we can probably ignore it.
+	 */
+	if (before(data_ack, prior_snd_una))
+		goto exit;
+
+	/* If the ack includes data we haven't sent yet, discard
+	 * this segment (RFC793 Section 3.9).
+	 */
+	if (after(data_ack, meta_tp->snd_nxt))
+		goto exit;
+
+	/*** Now, update the window  - inspired by tcp_ack_update_window ***/
+	nwin = ntohs(tcp_hdr(skb)->window);
+
+	if (likely(!tcp_hdr(skb)->syn))
+		nwin <<= tp->rx_opt.snd_wscale;
+
+	if (tcp_may_update_window(meta_tp, data_ack, data_seq, nwin)) {
+		tcp_update_wl(meta_tp, data_seq);
+
+		/* Draft v09, Section 3.3.5:
+		 * [...] It should only update its local receive window values
+		 * when the largest sequence number allowed (i.e.  DATA_ACK +
+		 * receive window) increases. [...]
+		 */
+		if (meta_tp->snd_wnd != nwin &&
+		    !before(data_ack + nwin, tcp_wnd_end(meta_tp))) {
+			meta_tp->snd_wnd = nwin;
+
+			if (nwin > meta_tp->max_window)
+				meta_tp->max_window = nwin;
+		}
+	}
+	/*** Done, update the window ***/
+
+	/* We passed data and got it acked, remove any soft error
+	 * log. Something worked...
+	 */
+	sk->sk_err_soft = 0;
+	inet_csk(meta_sk)->icsk_probes_out = 0;
+	meta_tp->rcv_tstamp = tcp_time_stamp;
+	prior_packets = meta_tp->packets_out;
+	if (!prior_packets)
+		goto no_queue;
+
+	meta_tp->snd_una = data_ack;
+
+	mptcp_clean_rtx_queue(meta_sk, prior_snd_una);
+
+	/* We are in loss-state, and something got acked, retransmit the whole
+	 * queue now!
+	 */
+	if (inet_csk(meta_sk)->icsk_ca_state == TCP_CA_Loss &&
+	    after(data_ack, prior_snd_una)) {
+		mptcp_xmit_retransmit_queue(meta_sk);
+		inet_csk(meta_sk)->icsk_ca_state = TCP_CA_Open;
+	}
+
+	/* Simplified version of tcp_new_space, because the snd-buffer
+	 * is handled by all the subflows.
+	 */
+	if (sock_flag(meta_sk, SOCK_QUEUE_SHRUNK)) {
+		sock_reset_flag(meta_sk, SOCK_QUEUE_SHRUNK);
+		if (meta_sk->sk_socket &&
+		    test_bit(SOCK_NOSPACE, &meta_sk->sk_socket->flags))
+			meta_sk->sk_write_space(meta_sk);
+	}
+
+	if (meta_sk->sk_state != TCP_ESTABLISHED)
+		mptcp_rcv_state_process(meta_sk, sk, skb, data_seq, data_len);
+
+exit:
+	mptcp_push_pending_frames(meta_sk);
+
+	return;
+
+no_queue:
+	if (tcp_send_head(meta_sk))
+		tcp_ack_probe(meta_sk);
+
+	mptcp_push_pending_frames(meta_sk);
+
+	return;
+}
+
+void mptcp_clean_rtx_infinite(struct sk_buff *skb, struct sock *sk)
+{
+	struct tcp_sock *tp = tcp_sk(sk), *meta_tp = tcp_sk(mptcp_meta_sk(sk));
+
+	if (!tp->mpcb->infinite_mapping_snd)
+		return;
+
+	/* The difference between both write_seq's represents the offset between
+	 * data-sequence and subflow-sequence. As we are infinite, this must
+	 * match.
+	 *
+	 * Thus, from this difference we can infer the meta snd_una.
+	 */
+	tp->mptcp->rx_opt.data_ack = meta_tp->snd_nxt - tp->snd_nxt +
+				     tp->snd_una;
+
+	mptcp_data_ack(sk, skb);
+}
+
+/**** static functions used by mptcp_parse_options */
+
+static inline int mptcp_rem_raddress(struct mptcp_cb *mpcb, u8 rem_id)
+{
+	if (mptcp_v4_rem_raddress(mpcb, rem_id) < 0) {
+#if IS_ENABLED(CONFIG_IPV6)
+		if (mptcp_v6_rem_raddress(mpcb, rem_id) < 0)
+			return -1;
+#else
+		return -1;
+#endif /* CONFIG_IPV6 */
+	}
+	return 0;
+}
+
+static void mptcp_send_reset_rem_id(const struct mptcp_cb *mpcb, u8 rem_id)
+{
+	struct sock *sk_it, *tmpsk;
+
+	mptcp_for_each_sk_safe(mpcb, sk_it, tmpsk) {
+		if (tcp_sk(sk_it)->mptcp->rem_id == rem_id) {
+			mptcp_reinject_data(sk_it, 0);
+			sk_it->sk_err = ECONNRESET;
+			if (tcp_need_reset(sk_it->sk_state))
+				tcp_send_active_reset(sk_it, GFP_ATOMIC);
+			mptcp_sub_force_close(sk_it);
+		}
+	}
+}
+
+void mptcp_parse_options(const uint8_t *ptr, int opsize,
+			 struct tcp_options_received *opt_rx,
+			 struct mptcp_options_received *mopt,
+			 const struct sk_buff *skb)
+{
+	struct mptcp_option *mp_opt = (struct mptcp_option *)ptr;
+
+	/* If the socket is mp-capable we would have a mopt. */
+	if (!mopt)
+		return;
+
+	switch (mp_opt->sub) {
+	case MPTCP_SUB_CAPABLE:
+	{
+		struct mp_capable *mpcapable = (struct mp_capable *)ptr;
+
+		if (opsize != MPTCP_SUB_LEN_CAPABLE_SYN &&
+		    opsize != MPTCP_SUB_LEN_CAPABLE_ACK) {
+			mptcp_debug("%s: mp_capable: bad option size %d\n",
+				    __func__, opsize);
+			break;
+		}
+
+		if (!sysctl_mptcp_enabled)
+			break;
+
+		/* We only support MPTCP version 0 */
+		if (mpcapable->ver != 0)
+			break;
+
+		/* MPTCP-RFC 6824:
+		 * "If receiving a message with the 'B' flag set to 1, and this
+		 * is not understood, then this SYN MUST be silently ignored;
+		 */
+		if (mpcapable->b) {
+			mopt->drop_me = 1;
+			break;
+		}
+
+		/* MPTCP-RFC 6824:
+		 * "An implementation that only supports this method MUST set
+		 *  bit "H" to 1, and bits "C" through "G" to 0."
+		 */
+		if (!mpcapable->h)
+			break;
+
+		mopt->saw_mpc = 1;
+		mopt->dss_csum = sysctl_mptcp_checksum || mpcapable->a;
+
+		if (opsize >= MPTCP_SUB_LEN_CAPABLE_SYN)
+			mopt->mptcp_key = mpcapable->sender_key;
+
+		break;
+	}
+	case MPTCP_SUB_JOIN:
+	{
+		struct mp_join *mpjoin = (struct mp_join *)ptr;
+
+		if (opsize != MPTCP_SUB_LEN_JOIN_SYN &&
+		    opsize != MPTCP_SUB_LEN_JOIN_SYNACK &&
+		    opsize != MPTCP_SUB_LEN_JOIN_ACK) {
+			mptcp_debug("%s: mp_join: bad option size %d\n",
+				    __func__, opsize);
+			break;
+		}
+
+		switch (opsize) {
+		case MPTCP_SUB_LEN_JOIN_SYN:
+			mopt->is_mp_join = 1;
+			mopt->low_prio = mpjoin->b;
+			mopt->rem_id = mpjoin->addr_id;
+			mopt->mptcp_rem_token = mpjoin->u.syn.token;
+			mopt->mptcp_recv_nonce = mpjoin->u.syn.nonce;
+			break;
+		case MPTCP_SUB_LEN_JOIN_SYNACK:
+			mopt->low_prio = mpjoin->b;
+			mopt->rem_id = mpjoin->addr_id;
+			mopt->mptcp_recv_tmac = mpjoin->u.synack.mac;
+			mopt->mptcp_recv_nonce = mpjoin->u.synack.nonce;
+			break;
+		case MPTCP_SUB_LEN_JOIN_ACK:
+			mopt->join_ack = 1;
+			memcpy(mopt->mptcp_recv_mac, mpjoin->u.ack.mac, 20);
+			break;
+		}
+		break;
+	}
+	case MPTCP_SUB_DSS:
+	{
+		struct mp_dss *mdss = (struct mp_dss *)ptr;
+		struct tcp_skb_cb *tcb = TCP_SKB_CB(skb);
+
+		/* We check opsize for the csum and non-csum case. We do this,
+		 * because the draft says that the csum SHOULD be ignored if
+		 * it has not been negotiated in the MP_CAPABLE but still is
+		 * present in the data.
+		 *
+		 * It will get ignored later in mptcp_queue_skb.
+		 */
+		if (opsize != mptcp_sub_len_dss(mdss, 0) &&
+		    opsize != mptcp_sub_len_dss(mdss, 1)) {
+			mptcp_debug("%s: mp_dss: bad option size %d\n",
+				    __func__, opsize);
+			break;
+		}
+
+		ptr += 4;
+
+		if (mdss->A) {
+			tcb->mptcp_flags |= MPTCPHDR_ACK;
+
+			if (mdss->a) {
+				mopt->data_ack = (u32) get_unaligned_be64(ptr);
+				ptr += MPTCP_SUB_LEN_ACK_64;
+			} else {
+				mopt->data_ack = get_unaligned_be32(ptr);
+				ptr += MPTCP_SUB_LEN_ACK;
+			}
+		}
+
+		tcb->dss_off = (ptr - skb_transport_header(skb));
+
+		if (mdss->M) {
+			if (mdss->m) {
+				u64 data_seq64 = get_unaligned_be64(ptr);
+
+				tcb->mptcp_flags |= MPTCPHDR_SEQ64_SET;
+				mopt->data_seq = (u32) data_seq64;
+
+				ptr += 12; /* 64-bit dseq + subseq */
+			} else {
+				mopt->data_seq = get_unaligned_be32(ptr);
+				ptr += 8; /* 32-bit dseq + subseq */
+			}
+			mopt->data_len = get_unaligned_be16(ptr);
+
+			tcb->mptcp_flags |= MPTCPHDR_SEQ;
+
+			/* Is a check-sum present? */
+			if (opsize == mptcp_sub_len_dss(mdss, 1))
+				tcb->mptcp_flags |= MPTCPHDR_DSS_CSUM;
+
+			/* DATA_FIN only possible with DSS-mapping */
+			if (mdss->F)
+				tcb->mptcp_flags |= MPTCPHDR_FIN;
+		}
+
+		break;
+	}
+	case MPTCP_SUB_ADD_ADDR:
+	{
+#if IS_ENABLED(CONFIG_IPV6)
+		struct mp_add_addr *mpadd = (struct mp_add_addr *)ptr;
+
+		if ((mpadd->ipver == 4 && opsize != MPTCP_SUB_LEN_ADD_ADDR4 &&
+		     opsize != MPTCP_SUB_LEN_ADD_ADDR4 + 2) ||
+		    (mpadd->ipver == 6 && opsize != MPTCP_SUB_LEN_ADD_ADDR6 &&
+		     opsize != MPTCP_SUB_LEN_ADD_ADDR6 + 2)) {
+#else
+		if (opsize != MPTCP_SUB_LEN_ADD_ADDR4 &&
+		    opsize != MPTCP_SUB_LEN_ADD_ADDR4 + 2) {
+#endif /* CONFIG_IPV6 */
+			mptcp_debug("%s: mp_add_addr: bad option size %d\n",
+				    __func__, opsize);
+			break;
+		}
+
+		/* We have to manually parse the options if we got two of them. */
+		if (mopt->saw_add_addr) {
+			mopt->more_add_addr = 1;
+			break;
+		}
+		mopt->saw_add_addr = 1;
+		mopt->add_addr_ptr = ptr;
+		break;
+	}
+	case MPTCP_SUB_REMOVE_ADDR:
+		if ((opsize - MPTCP_SUB_LEN_REMOVE_ADDR) < 0) {
+			mptcp_debug("%s: mp_remove_addr: bad option size %d\n",
+				    __func__, opsize);
+			break;
+		}
+
+		if (mopt->saw_rem_addr) {
+			mopt->more_rem_addr = 1;
+			break;
+		}
+		mopt->saw_rem_addr = 1;
+		mopt->rem_addr_ptr = ptr;
+		break;
+	case MPTCP_SUB_PRIO:
+	{
+		struct mp_prio *mpprio = (struct mp_prio *)ptr;
+
+		if (opsize != MPTCP_SUB_LEN_PRIO &&
+		    opsize != MPTCP_SUB_LEN_PRIO_ADDR) {
+			mptcp_debug("%s: mp_prio: bad option size %d\n",
+				    __func__, opsize);
+			break;
+		}
+
+		mopt->saw_low_prio = 1;
+		mopt->low_prio = mpprio->b;
+
+		if (opsize == MPTCP_SUB_LEN_PRIO_ADDR) {
+			mopt->saw_low_prio = 2;
+			mopt->prio_addr_id = mpprio->addr_id;
+		}
+		break;
+	}
+	case MPTCP_SUB_FAIL:
+		if (opsize != MPTCP_SUB_LEN_FAIL) {
+			mptcp_debug("%s: mp_fail: bad option size %d\n",
+				    __func__, opsize);
+			break;
+		}
+		mopt->mp_fail = 1;
+		break;
+	case MPTCP_SUB_FCLOSE:
+		if (opsize != MPTCP_SUB_LEN_FCLOSE) {
+			mptcp_debug("%s: mp_fclose: bad option size %d\n",
+				    __func__, opsize);
+			break;
+		}
+
+		mopt->mp_fclose = 1;
+		mopt->mptcp_key = ((struct mp_fclose *)ptr)->key;
+
+		break;
+	default:
+		mptcp_debug("%s: Received unkown subtype: %d\n",
+			    __func__, mp_opt->sub);
+		break;
+	}
+}
+
+int mptcp_check_rtt(const struct tcp_sock *tp, int time)
+{
+	struct mptcp_cb *mpcb = tp->mpcb;
+	struct sock *sk;
+	u32 rtt_max = 0;
+
+	/* In MPTCP, we take the max delay across all flows,
+	 * in order to take into account meta-reordering buffers.
+	 */
+	mptcp_for_each_sk(mpcb, sk) {
+		if (!mptcp_sk_can_recv(sk))
+			continue;
+
+		if (rtt_max < tcp_sk(sk)->rcv_rtt_est.rtt)
+			rtt_max = tcp_sk(sk)->rcv_rtt_est.rtt;
+	}
+	if (time < (rtt_max >> 3) || !rtt_max)
+		return 1;
+
+	return 0;
+}
+
+static void mptcp_handle_add_addr(const unsigned char *ptr, struct sock *sk)
+{
+	struct mp_add_addr *mpadd = (struct mp_add_addr *)ptr;
+
+	if (mpadd->ipver == 4) {
+		__be16 port = 0;
+		if (mpadd->len == MPTCP_SUB_LEN_ADD_ADDR4 + 2)
+			port  = mpadd->u.v4.port;
+
+		mptcp_v4_add_raddress(tcp_sk(sk)->mpcb, &mpadd->u.v4.addr, port,
+				      mpadd->addr_id);
+#if IS_ENABLED(CONFIG_IPV6)
+	} else if (mpadd->ipver == 6) {
+		__be16 port = 0;
+		if (mpadd->len == MPTCP_SUB_LEN_ADD_ADDR6 + 2)
+			port  = mpadd->u.v6.port;
+
+		mptcp_v6_add_raddress(tcp_sk(sk)->mpcb, &mpadd->u.v6.addr, port,
+				      mpadd->addr_id);
+#endif /* CONFIG_IPV6 */
+	}
+}
+
+static void mptcp_handle_rem_addr(const unsigned char *ptr, struct sock *sk)
+{
+	struct mp_remove_addr *mprem = (struct mp_remove_addr *)ptr;
+	int i;
+	u8 rem_id;
+
+	for (i = 0; i <= mprem->len - MPTCP_SUB_LEN_REMOVE_ADDR; i++) {
+		rem_id = (&mprem->addrs_id)[i];
+		if (!mptcp_rem_raddress(tcp_sk(sk)->mpcb, rem_id))
+			mptcp_send_reset_rem_id(tcp_sk(sk)->mpcb, rem_id);
+	}
+}
+
+static void mptcp_parse_addropt(const struct sk_buff *skb, struct sock *sk)
+{
+	struct tcphdr *th = tcp_hdr(skb);
+	unsigned char *ptr;
+	int length = (th->doff * 4) - sizeof(struct tcphdr);
+
+	/* Jump through the options to check whether ADD_ADDR is there */
+	ptr = (unsigned char *)(th + 1);
+	while (length > 0) {
+		int opcode = *ptr++;
+		int opsize;
+
+		switch (opcode) {
+		case TCPOPT_EOL:
+			return;
+		case TCPOPT_NOP:
+			length--;
+			continue;
+		default:
+			opsize = *ptr++;
+			if (opsize < 2)
+				return;
+			if (opsize > length)
+				return;  /* don't parse partial options */
+			if (opcode == TCPOPT_MPTCP &&
+			    ((struct mptcp_option *)ptr)->sub == MPTCP_SUB_ADD_ADDR) {
+#if IS_ENABLED(CONFIG_IPV6)
+				struct mp_add_addr *mpadd = (struct mp_add_addr *)ptr;
+				if ((mpadd->ipver == 4 && opsize != MPTCP_SUB_LEN_ADD_ADDR4 &&
+				     opsize != MPTCP_SUB_LEN_ADD_ADDR4 + 2) ||
+				    (mpadd->ipver == 6 && opsize != MPTCP_SUB_LEN_ADD_ADDR6 &&
+				     opsize != MPTCP_SUB_LEN_ADD_ADDR6 + 2))
+#else
+				if (opsize != MPTCP_SUB_LEN_ADD_ADDR4 &&
+				    opsize != MPTCP_SUB_LEN_ADD_ADDR4 + 2)
+#endif /* CONFIG_IPV6 */
+					goto cont;
+
+				mptcp_handle_add_addr(ptr, sk);
+			}
+			if (opcode == TCPOPT_MPTCP &&
+			    ((struct mptcp_option *)ptr)->sub == MPTCP_SUB_REMOVE_ADDR) {
+				if ((opsize - MPTCP_SUB_LEN_REMOVE_ADDR) < 0)
+					goto cont;
+
+				mptcp_handle_rem_addr(ptr, sk);
+			}
+cont:
+			ptr += opsize - 2;
+			length -= opsize;
+		}
+	}
+	return;
+}
+
+static inline int mptcp_mp_fail_rcvd(struct sock *sk, const struct tcphdr *th)
+{
+	struct mptcp_tcp_sock *mptcp = tcp_sk(sk)->mptcp;
+	struct sock *meta_sk = mptcp_meta_sk(sk);
+	struct mptcp_cb *mpcb = tcp_sk(sk)->mpcb;
+
+	if (unlikely(mptcp->rx_opt.mp_fail)) {
+		mptcp->rx_opt.mp_fail = 0;
+
+		if (!th->rst && !mpcb->infinite_mapping_snd) {
+			struct sock *sk_it;
+
+			mpcb->send_infinite_mapping = 1;
+			/* We resend everything that has not been acknowledged */
+			meta_sk->sk_send_head = tcp_write_queue_head(meta_sk);
+
+			/* We artificially restart the whole send-queue. Thus,
+			 * it is as if no packets are in flight
+			 */
+			tcp_sk(meta_sk)->packets_out = 0;
+
+			/* If the snd_nxt already wrapped around, we have to
+			 * undo the wrapping, as we are restarting from snd_una
+			 * on.
+			 */
+			if (tcp_sk(meta_sk)->snd_nxt < tcp_sk(meta_sk)->snd_una) {
+				mpcb->snd_high_order[mpcb->snd_hiseq_index] -= 2;
+				mpcb->snd_hiseq_index = mpcb->snd_hiseq_index ? 0 : 1;
+			}
+			tcp_sk(meta_sk)->snd_nxt = tcp_sk(meta_sk)->snd_una;
+
+			/* Trigger a sending on the meta. */
+			mptcp_push_pending_frames(meta_sk);
+
+			mptcp_for_each_sk(mpcb, sk_it) {
+				if (sk != sk_it)
+					mptcp_sub_force_close(sk_it);
+			}
+		}
+
+		return 0;
+	}
+
+	if (unlikely(mptcp->rx_opt.mp_fclose)) {
+		struct sock *sk_it, *tmpsk;
+
+		mptcp->rx_opt.mp_fclose = 0;
+		if (mptcp->rx_opt.mptcp_key != mpcb->mptcp_loc_key)
+			return 0;
+
+		if (tcp_need_reset(sk->sk_state))
+			tcp_send_active_reset(sk, GFP_ATOMIC);
+
+		mptcp_for_each_sk_safe(mpcb, sk_it, tmpsk)
+			mptcp_sub_force_close(sk_it);
+
+		tcp_reset(meta_sk);
+
+		return 1;
+	}
+
+	return 0;
+}
+
+static inline void mptcp_path_array_check(struct sock *meta_sk)
+{
+	struct mptcp_cb *mpcb = tcp_sk(meta_sk)->mpcb;
+
+	if (unlikely(mpcb->list_rcvd)) {
+		mpcb->list_rcvd = 0;
+		mptcp_create_subflows(meta_sk);
+	}
+}
+
+int mptcp_handle_options(struct sock *sk, const struct tcphdr *th, struct sk_buff *skb)
+{
+	struct tcp_sock *tp = tcp_sk(sk);
+	struct mptcp_options_received *mopt = &tp->mptcp->rx_opt;
+
+	if (tp->mpcb->infinite_mapping_rcv || tp->mpcb->infinite_mapping_snd)
+		return 0;
+
+	if (mptcp_mp_fail_rcvd(sk, th))
+		return 1;
+
+	/* RFC 6824, Section 3.3:
+	 * If a checksum is not present when its use has been negotiated, the
+	 * receiver MUST close the subflow with a RST as it is considered broken.
+	 */
+	if (mptcp_is_data_seq(skb) && tp->mpcb->dss_csum &&
+	    !(TCP_SKB_CB(skb)->mptcp_flags & MPTCPHDR_DSS_CSUM)) {
+		if (tcp_need_reset(sk->sk_state))
+			tcp_send_active_reset(sk, GFP_ATOMIC);
+
+		mptcp_sub_force_close(sk);
+		return 1;
+	}
+
+	/* We have to acknowledge retransmissions of the third
+	 * ack.
+	 */
+	if (mopt->join_ack) {
+		tcp_send_delayed_ack(sk);
+		mopt->join_ack = 0;
+	}
+
+	if (mopt->saw_add_addr || mopt->saw_rem_addr) {
+		if (mopt->more_add_addr || mopt->more_rem_addr) {
+			mptcp_parse_addropt(skb, sk);
+		} else {
+			if (mopt->saw_add_addr)
+				mptcp_handle_add_addr(mopt->add_addr_ptr, sk);
+			if (mopt->saw_rem_addr)
+				mptcp_handle_rem_addr(mopt->rem_addr_ptr, sk);
+		}
+
+		mopt->more_add_addr = 0;
+		mopt->saw_add_addr = 0;
+		mopt->more_rem_addr = 0;
+		mopt->saw_rem_addr = 0;
+	}
+	if (mopt->saw_low_prio) {
+		if (mopt->saw_low_prio == 1) {
+			tp->mptcp->rcv_low_prio = mopt->low_prio;
+		} else {
+			struct sock *sk_it;
+			mptcp_for_each_sk(tp->mpcb, sk_it) {
+				struct mptcp_tcp_sock *mptcp = tcp_sk(sk_it)->mptcp;
+				if (mptcp->rem_id == mopt->prio_addr_id)
+					mptcp->rcv_low_prio = mopt->low_prio;
+			}
+		}
+		mopt->saw_low_prio = 0;
+	}
+
+	mptcp_data_ack(sk, skb);
+
+	mptcp_path_array_check(mptcp_meta_sk(sk));
+	/* Socket may have been mp_killed by a REMOVE_ADDR */
+	if (tp->mp_killed)
+		return 1;
+
+	return 0;
+}
+
+/* The skptr is needed, because if we become MPTCP-capable, we have to switch
+ * from meta-socket to master-socket.
+ *
+ * @return: 1 - we want to reset this connection
+ * 	    2 - we want to discard the received syn/ack
+ * 	    0 - everything is fine - continue
+ */
+int mptcp_rcv_synsent_state_process(struct sock *sk, struct sock **skptr,
+				    struct sk_buff *skb,
+				    struct mptcp_options_received *mopt)
+{
+	struct tcp_sock *tp = tcp_sk(sk);
+
+	if (tp->mpc) {
+		u8 hash_mac_check[20];
+		struct mptcp_cb *mpcb = tp->mpcb;
+
+		mptcp_hmac_sha1((u8 *)&mpcb->mptcp_rem_key,
+				(u8 *)&mpcb->mptcp_loc_key,
+				(u8 *)&tp->mptcp->rx_opt.mptcp_recv_nonce,
+				(u8 *)&tp->mptcp->mptcp_loc_nonce,
+				(u32 *)hash_mac_check);
+		if (memcmp(hash_mac_check,
+			   (char *)&tp->mptcp->rx_opt.mptcp_recv_tmac, 8)) {
+			mptcp_sub_force_close(sk);
+			return 1;
+		}
+
+		/* Set this flag in order to postpone data sending
+		 * until the 4th ack arrives.
+		 */
+		tp->mptcp->pre_established = 1;
+		tp->mptcp->rcv_low_prio = tp->mptcp->rx_opt.low_prio;
+
+		mptcp_hmac_sha1((u8 *)&mpcb->mptcp_loc_key,
+				(u8 *)&mpcb->mptcp_rem_key,
+				(u8 *)&tp->mptcp->mptcp_loc_nonce,
+				(u8 *)&tp->mptcp->rx_opt.mptcp_recv_nonce,
+				(u32 *)&tp->mptcp->sender_mac[0]);
+
+	} else if (mopt->saw_mpc) {
+		if (mptcp_create_master_sk(sk, mopt->mptcp_key,
+					   ntohs(tcp_hdr(skb)->window)))
+			return 2;
+
+		sk = tcp_sk(sk)->mpcb->master_sk;
+		*skptr = sk;
+		tp = tcp_sk(sk);
+
+		/* snd_nxt - 1, because it has been incremented
+		 * by tcp_connect for the SYN
+		 */
+		tp->mptcp->snt_isn = tp->snd_nxt - 1;
+		tp->mpcb->dss_csum = mopt->dss_csum;
+		tp->mptcp->include_mpc = 1;
+
+		sk_set_socket(sk, mptcp_meta_sk(sk)->sk_socket);
+		sk->sk_wq = mptcp_meta_sk(sk)->sk_wq;
+
+		mptcp_update_metasocket(sk, mptcp_meta_sk(sk));
+
+		 /* hold in mptcp_inherit_sk due to initialization to 2 */
+		sock_put(sk);
+	} else {
+		tp->request_mptcp = 0;
+
+		if (tp->inside_tk_table)
+			mptcp_hash_remove(tp);
+	}
+
+	if (tp->mpc)
+		tp->mptcp->rcv_isn = TCP_SKB_CB(skb)->seq;
+
+	return 0;
+}
diff -Naur a/net/mptcp/mptcp_ipv4.c b/net/mptcp/mptcp_ipv4.c
--- a/net/mptcp/mptcp_ipv4.c	1970-01-01 01:00:00.000000000 +0100
+++ b/net/mptcp/mptcp_ipv4.c	2013-10-06 18:27:11.121028568 +0200
@@ -0,0 +1,726 @@
+/*
+ *	MPTCP implementation - IPv4-specific functions
+ *
+ *	Initial Design & Implementation:
+ *	Sébastien Barré <[e-mail]>
+ *
+ *	Current Maintainer:
+ *	Christoph Paasch <[e-mail]>
+ *
+ *	Additional authors:
+ *	Jaakko Korkeaniemi <[e-mail]>
+ *	Gregory Detal <[e-mail]>
+ *	Fabien Duchêne <[e-mail]>
+ *	Andreas Seelinger <[e-mail]>
+ *	Lavkesh Lahngir <[e-mail]>
+ *	Andreas Ripke <[e-mail]>
+ *	Vlad Dogaru <[e-mail]>
+ *	Octavian Purdila <[e-mail]>
+ *	John Ronan <[e-mail]>
+ *	Catalin Nicutar <[e-mail]>
+ *	Brandon Heller <[e-mail]>
+ *
+ *
+ *	This program is free software; you can redistribute it and/or
+ *      modify it under the terms of the GNU General Public License
+ *      as published by the Free Software Foundation; either version
+ *      2 of the License, or (at your option) any later version.
+ */
+
+#include <linux/export.h>
+#include <linux/ip.h>
+#include <linux/list.h>
+#include <linux/skbuff.h>
+#include <linux/spinlock.h>
+#include <linux/tcp.h>
+
+#include <net/inet_common.h>
+#include <net/inet_connection_sock.h>
+#include <net/mptcp.h>
+#include <net/mptcp_pm.h>
+#include <net/mptcp_v4.h>
+#include <net/mptcp_v6.h>
+#include <net/request_sock.h>
+#include <net/tcp.h>
+
+u32 mptcp_v4_get_nonce(__be32 saddr, __be32 daddr, __be16 sport, __be16 dport,
+		       u32 seq)
+{
+	u32 hash[MD5_DIGEST_WORDS];
+
+	hash[0] = (__force u32)saddr;
+	hash[1] = (__force u32)daddr;
+	hash[2] = ((__force u16)sport << 16) + (__force u16)dport;
+	hash[3] = seq;
+
+	md5_transform(hash, mptcp_secret);
+
+	return hash[0];
+}
+
+u64 mptcp_v4_get_key(__be32 saddr, __be32 daddr, __be16 sport, __be16 dport)
+{
+	u32 hash[MD5_DIGEST_WORDS];
+
+	hash[0] = (__force u32)saddr;
+	hash[1] = (__force u32)daddr;
+	hash[2] = ((__force u16)sport << 16) + (__force u16)dport;
+	hash[3] = mptcp_key_seed++;
+
+	md5_transform(hash, mptcp_secret);
+
+	return *((u64 *)hash);
+}
+
+
+static void mptcp_v4_reqsk_destructor(struct request_sock *req)
+{
+	mptcp_reqsk_destructor(req);
+
+	tcp_v4_reqsk_destructor(req);
+}
+
+/* Similar to tcp_request_sock_ops */
+struct request_sock_ops mptcp_request_sock_ops __read_mostly = {
+	.family		=	PF_INET,
+	.obj_size	=	sizeof(struct mptcp_request_sock),
+	.rtx_syn_ack	=	tcp_v4_rtx_synack,
+	.send_ack	=	tcp_v4_reqsk_send_ack,
+	.destructor	=	mptcp_v4_reqsk_destructor,
+	.send_reset	=	tcp_v4_send_reset,
+	.syn_ack_timeout =	tcp_syn_ack_timeout,
+};
+
+static void mptcp_v4_reqsk_queue_hash_add(struct sock *meta_sk,
+					  struct request_sock *req,
+					  unsigned long timeout)
+{
+	const u32 h = inet_synq_hash(inet_rsk(req)->rmt_addr,
+				     inet_rsk(req)->rmt_port,
+				     0, MPTCP_HASH_SIZE);
+
+	inet_csk_reqsk_queue_hash_add(meta_sk, req, timeout);
+
+	spin_lock(&mptcp_reqsk_hlock);
+	list_add(&mptcp_rsk(req)->collide_tuple, &mptcp_reqsk_htb[h]);
+	spin_unlock(&mptcp_reqsk_hlock);
+}
+
+/* Similar to tcp_v4_conn_request */
+static void mptcp_v4_join_request(struct sock *meta_sk, struct sk_buff *skb)
+{
+	struct mptcp_cb *mpcb = tcp_sk(meta_sk)->mpcb;
+	struct tcp_options_received tmp_opt;
+	struct mptcp_options_received mopt;
+	struct request_sock *req;
+	struct inet_request_sock *ireq;
+	struct mptcp_request_sock *mtreq;
+	struct dst_entry *dst = NULL;
+	u8 mptcp_hash_mac[20];
+	__be32 saddr = ip_hdr(skb)->saddr;
+	__be32 daddr = ip_hdr(skb)->daddr;
+	__u32 isn = TCP_SKB_CB(skb)->when;
+	int want_cookie = 0;
+
+	tcp_clear_options(&tmp_opt);
+	mptcp_init_mp_opt(&mopt);
+	tmp_opt.mss_clamp = TCP_MSS_DEFAULT;
+	tmp_opt.user_mss = tcp_sk(meta_sk)->rx_opt.user_mss;
+	tcp_parse_options(skb, &tmp_opt, &mopt, 0, NULL);
+
+	req = inet_reqsk_alloc(&mptcp_request_sock_ops);
+	if (!req)
+		return;
+
+	tmp_opt.tstamp_ok = tmp_opt.saw_tstamp;
+	tcp_openreq_init(req, &tmp_opt, skb);
+
+	ireq = inet_rsk(req);
+	ireq->loc_addr = daddr;
+	ireq->rmt_addr = saddr;
+	ireq->no_srccheck = inet_sk(meta_sk)->transparent;
+	ireq->opt = tcp_v4_save_options(skb);
+
+	if (security_inet_conn_request(meta_sk, skb, req))
+		goto drop_and_free;
+
+	if (!want_cookie || tmp_opt.tstamp_ok)
+		TCP_ECN_create_request(req, skb, sock_net(meta_sk));
+
+	if (!isn) {
+		struct flowi4 fl4;
+
+		/* VJ's idea. We save last timestamp seen
+		 * from the destination in peer table, when entering
+		 * state TIME-WAIT, and check against it before
+		 * accepting new connection request.
+		 *
+		 * If "isn" is not zero, this request hit alive
+		 * timewait bucket, so that all the necessary checks
+		 * are made in the function processing timewait state.
+		 */
+		if (tmp_opt.saw_tstamp &&
+		    tcp_death_row.sysctl_tw_recycle &&
+		    (dst = inet_csk_route_req(meta_sk, &fl4, req)) != NULL &&
+		    fl4.daddr == saddr) {
+			if (!tcp_peer_is_proven(req, dst, true)) {
+				NET_INC_STATS_BH(sock_net(meta_sk), LINUX_MIB_PAWSPASSIVEREJECTED);
+				goto drop_and_release;
+			}
+		}
+		/* Kill the following clause, if you dislike this way. */
+		else if (!sysctl_tcp_syncookies &&
+			 (sysctl_max_syn_backlog - inet_csk_reqsk_queue_len(meta_sk) <
+			  (sysctl_max_syn_backlog >> 2)) &&
+			 !tcp_peer_is_proven(req, dst, false)) {
+			/* Without syncookies last quarter of
+			 * backlog is filled with destinations,
+			 * proven to be alive.
+			 * It means that we continue to communicate
+			 * to destinations, already remembered
+			 * to the moment of synflood.
+			 */
+			LIMIT_NETDEBUG(KERN_DEBUG pr_fmt("drop open request from %pI4/%u\n"),
+				       &saddr, ntohs(tcp_hdr(skb)->source));
+			goto drop_and_release;
+		}
+
+		isn = tcp_v4_init_sequence(skb);
+	}
+	tcp_rsk(req)->snt_isn = isn;
+	tcp_rsk(req)->snt_synack = tcp_time_stamp;
+
+	mtreq = mptcp_rsk(req);
+	mtreq->mpcb = mpcb;
+	INIT_LIST_HEAD(&mtreq->collide_tuple);
+	mtreq->mptcp_rem_nonce = mopt.mptcp_recv_nonce;
+	mtreq->mptcp_rem_key = mpcb->mptcp_rem_key;
+	mtreq->mptcp_loc_key = mpcb->mptcp_loc_key;
+	mtreq->mptcp_loc_nonce = mptcp_v4_get_nonce(saddr, daddr,
+						    tcp_hdr(skb)->source,
+						    tcp_hdr(skb)->dest, isn);
+	mptcp_hmac_sha1((u8 *)&mtreq->mptcp_loc_key,
+			(u8 *)&mtreq->mptcp_rem_key,
+			(u8 *)&mtreq->mptcp_loc_nonce,
+			(u8 *)&mtreq->mptcp_rem_nonce, (u32 *)mptcp_hash_mac);
+	mtreq->mptcp_hash_tmac = *(u64 *)mptcp_hash_mac;
+	mtreq->rem_id = mopt.rem_id;
+	mtreq->low_prio = mopt.low_prio;
+	tcp_rsk(req)->saw_mpc = 1;
+
+	if (tcp_v4_send_synack(meta_sk, dst, req, skb_get_queue_mapping(skb), want_cookie))
+		goto drop_and_free;
+
+	/* Adding to request queue in metasocket */
+	mptcp_v4_reqsk_queue_hash_add(meta_sk, req, TCP_TIMEOUT_INIT);
+
+	return;
+
+drop_and_release:
+	dst_release(dst);
+drop_and_free:
+	reqsk_free(req);
+	return;
+}
+
+int mptcp_v4_rem_raddress(struct mptcp_cb *mpcb, u8 id)
+{
+	int i;
+
+	for (i = 0; i < MPTCP_MAX_ADDR; i++) {
+		if (!((1 << i) & mpcb->rem4_bits))
+			continue;
+
+		if (mpcb->remaddr4[i].id == id) {
+			/* remove address from bitfield */
+			mpcb->rem4_bits &= ~(1 << i);
+
+			return 0;
+		}
+	}
+
+	return -1;
+}
+
+/* Based on function tcp_v4_conn_request (tcp_ipv4.c)
+ * Returns -1 if there is no space anymore to store an additional
+ * address
+ */
+int mptcp_v4_add_raddress(struct mptcp_cb *mpcb, const struct in_addr *addr,
+			  __be16 port, u8 id)
+{
+	int i;
+	struct mptcp_rem4 *rem4;
+
+	mptcp_for_each_bit_set(mpcb->rem4_bits, i) {
+		rem4 = &mpcb->remaddr4[i];
+
+		/* Address is already in the list --- continue */
+		if (rem4->id == id &&
+		    rem4->addr.s_addr == addr->s_addr && rem4->port == port)
+			return 0;
+
+		/* This may be the case, when the peer is behind a NAT. He is
+		 * trying to JOIN, thus sending the JOIN with a certain ID.
+		 * However the src_addr of the IP-packet has been changed. We
+		 * update the addr in the list, because this is the address as
+		 * OUR BOX sees it.
+		 */
+		if (rem4->id == id && rem4->addr.s_addr != addr->s_addr) {
+			/* update the address */
+			mptcp_debug("%s: updating old addr:%pI4 to addr %pI4 with id:%d\n",
+				    __func__, &rem4->addr.s_addr,
+				    &addr->s_addr, id);
+			rem4->addr.s_addr = addr->s_addr;
+			rem4->port = port;
+			mpcb->list_rcvd = 1;
+			return 0;
+		}
+	}
+
+	i = mptcp_find_free_index(mpcb->rem4_bits);
+	/* Do we have already the maximum number of local/remote addresses? */
+	if (i < 0) {
+		mptcp_debug("%s: At max num of remote addresses: %d --- not adding address: %pI4\n",
+			    __func__, MPTCP_MAX_ADDR, &addr->s_addr);
+		return -1;
+	}
+
+	rem4 = &mpcb->remaddr4[i];
+
+	/* Address is not known yet, store it */
+	rem4->addr.s_addr = addr->s_addr;
+	rem4->port = port;
+	rem4->bitfield = 0;
+	rem4->retry_bitfield = 0;
+	rem4->id = id;
+	mpcb->list_rcvd = 1;
+	mpcb->rem4_bits |= (1 << i);
+
+	return 0;
+}
+
+/* Sets the bitfield of the remote-address field
+ * local address is not set as it will disappear with the global address-list
+ */
+void mptcp_v4_set_init_addr_bit(struct mptcp_cb *mpcb, __be32 daddr)
+{
+	int i;
+
+	mptcp_for_each_bit_set(mpcb->rem4_bits, i) {
+		if (mpcb->remaddr4[i].addr.s_addr == daddr) {
+			/* It's the initial flow - thus local index == 0 */
+			mpcb->remaddr4[i].bitfield |= 1;
+			return;
+		}
+	}
+}
+
+/* We only process join requests here. (either the SYN or the final ACK) */
+int mptcp_v4_do_rcv(struct sock *meta_sk, struct sk_buff *skb)
+{
+	struct mptcp_cb *mpcb = tcp_sk(meta_sk)->mpcb;
+	struct sock *child, *rsk = NULL;
+	int ret;
+
+	if (!(TCP_SKB_CB(skb)->mptcp_flags & MPTCPHDR_JOIN)) {
+		struct tcphdr *th = tcp_hdr(skb);
+		const struct iphdr *iph = ip_hdr(skb);
+		struct sock *sk;
+
+		sk = inet_lookup_established(sock_net(meta_sk), &tcp_hashinfo,
+					     iph->saddr, th->source, iph->daddr,
+					     th->dest, inet_iif(skb));
+
+		if (!sk) {
+			kfree_skb(skb);
+			return 0;
+		}
+		if (is_meta_sk(sk)) {
+			WARN("%s Did not find a sub-sk - did found the meta!\n", __func__);
+			kfree_skb(skb);
+			sock_put(sk);
+			return 0;
+		}
+
+		if (sk->sk_state == TCP_TIME_WAIT) {
+			inet_twsk_put(inet_twsk(sk));
+			kfree_skb(skb);
+			return 0;
+		}
+
+		ret = tcp_v4_do_rcv(sk, skb);
+		sock_put(sk);
+
+		return ret;
+	}
+	TCP_SKB_CB(skb)->mptcp_flags = 0;
+
+	/* Has been removed from the tk-table. Thus, no new subflows.
+	 *
+	 * Check for close-state is necessary, because we may have been closed
+	 * without passing by mptcp_close().
+	 *
+	 * When falling back, no new subflows are allowed either.
+	 */
+	if (meta_sk->sk_state == TCP_CLOSE || !tcp_sk(meta_sk)->inside_tk_table ||
+	    mpcb->infinite_mapping_rcv || mpcb->send_infinite_mapping)
+		goto reset_and_discard;
+
+	child = tcp_v4_hnd_req(meta_sk, skb);
+
+	if (!child)
+		goto discard;
+
+	if (child != meta_sk) {
+		sock_rps_save_rxhash(child, skb);
+		/* We don't call tcp_child_process here, because we hold
+		 * already the meta-sk-lock and are sure that it is not owned
+		 * by the user.
+		 */
+		ret = tcp_rcv_state_process(child, skb, tcp_hdr(skb), skb->len);
+		bh_unlock_sock(child);
+		sock_put(child);
+		if (ret) {
+			rsk = child;
+			goto reset_and_discard;
+		}
+	} else {
+		if (tcp_hdr(skb)->syn) {
+			struct mp_join *join_opt = mptcp_find_join(skb);
+			/* Currently we make two calls to mptcp_find_join(). This
+			 * can probably be optimized.
+			 */
+			if (mptcp_v4_add_raddress(mpcb,
+						  (struct in_addr *)&ip_hdr(skb)->saddr,
+						  0,
+						  join_opt->addr_id) < 0)
+				goto reset_and_discard;
+			mpcb->list_rcvd = 0;
+
+			mptcp_v4_join_request(meta_sk, skb);
+			goto discard;
+		}
+		goto reset_and_discard;
+	}
+	return 0;
+
+reset_and_discard:
+	tcp_v4_send_reset(rsk, skb);
+discard:
+	kfree_skb(skb);
+	return 0;
+}
+
+/* After this, the ref count of the meta_sk associated with the request_sock
+ * is incremented. Thus it is the responsibility of the caller
+ * to call sock_put() when the reference is not needed anymore.
+ */
+struct sock *mptcp_v4_search_req(const __be16 rport, const __be32 raddr,
+				 const __be32 laddr, const struct net *net)
+{
+	struct mptcp_request_sock *mtreq;
+	struct sock *meta_sk = NULL;
+
+	spin_lock(&mptcp_reqsk_hlock);
+	list_for_each_entry(mtreq,
+			    &mptcp_reqsk_htb[inet_synq_hash(raddr, rport, 0,
+							    MPTCP_HASH_SIZE)],
+			    collide_tuple) {
+		struct inet_request_sock *ireq = inet_rsk(rev_mptcp_rsk(mtreq));
+		meta_sk = mtreq->mpcb->meta_sk;
+
+		if (ireq->rmt_port == rport &&
+		    ireq->rmt_addr == raddr &&
+		    ireq->loc_addr == laddr &&
+		    rev_mptcp_rsk(mtreq)->rsk_ops->family == AF_INET &&
+		    net_eq(net, sock_net(meta_sk)))
+			break;
+		meta_sk = NULL;
+	}
+
+	if (meta_sk && unlikely(!atomic_inc_not_zero(&meta_sk->sk_refcnt)))
+		meta_sk = NULL;
+	spin_unlock(&mptcp_reqsk_hlock);
+
+	return meta_sk;
+}
+
+/* Create a new IPv4 subflow.
+ *
+ * We are in user-context and meta-sock-lock is hold.
+ */
+int mptcp_init4_subsockets(struct sock *meta_sk, const struct mptcp_loc4 *loc,
+			   struct mptcp_rem4 *rem)
+{
+	struct tcp_sock *tp;
+	struct sock *sk;
+	struct sockaddr_in loc_in, rem_in;
+	struct socket sock;
+	int ulid_size = 0, ret;
+
+	/* Don't try again - even if it fails */
+	rem->bitfield |= (1 << loc->id);
+
+	/** First, create and prepare the new socket */
+
+	sock.type = meta_sk->sk_socket->type;
+	sock.state = SS_UNCONNECTED;
+	sock.wq = meta_sk->sk_socket->wq;
+	sock.file = meta_sk->sk_socket->file;
+	sock.ops = NULL;
+
+	ret = inet_create(sock_net(meta_sk), &sock, IPPROTO_TCP, 1);
+	if (unlikely(ret < 0)) {
+		mptcp_debug("%s inet_create failed ret: %d\n", __func__, ret);
+		return ret;
+	}
+
+	sk = sock.sk;
+	tp = tcp_sk(sk);
+
+	/* All subsockets need the MPTCP-lock-class */
+	lockdep_set_class_and_name(&(sk)->sk_lock.slock, &meta_slock_key, "slock-AF_INET-MPTCP");
+	lockdep_init_map(&(sk)->sk_lock.dep_map, "sk_lock-AF_INET-MPTCP", &meta_key, 0);
+
+	if (mptcp_add_sock(meta_sk, sk, rem->id, GFP_KERNEL))
+		goto error;
+
+	tp->mptcp->slave_sk = 1;
+	tp->mptcp->low_prio = loc->low_prio;
+
+	/* Initializing the timer for an MPTCP subflow */
+	setup_timer(&tp->mptcp->mptcp_ack_timer, mptcp_ack_handler, (unsigned long)sk);
+
+	/** Then, connect the socket to the peer */
+
+	ulid_size = sizeof(struct sockaddr_in);
+	loc_in.sin_family = AF_INET;
+	rem_in.sin_family = AF_INET;
+	loc_in.sin_port = 0;
+	if (rem->port)
+		rem_in.sin_port = rem->port;
+	else
+		rem_in.sin_port = inet_sk(meta_sk)->inet_dport;
+	loc_in.sin_addr = loc->addr;
+	rem_in.sin_addr = rem->addr;
+
+	ret = sock.ops->bind(&sock, (struct sockaddr *)&loc_in, ulid_size);
+	if (ret < 0) {
+		mptcp_debug("%s: MPTCP subsocket bind() failed, error %d\n",
+			    __func__, ret);
+		goto error;
+	}
+
+	mptcp_debug("%s: token %#x pi %d src_addr:%pI4:%d dst_addr:%pI4:%d\n",
+		    __func__, tcp_sk(meta_sk)->mpcb->mptcp_loc_token,
+		    tp->mptcp->path_index, &loc_in.sin_addr,
+		    ntohs(loc_in.sin_port), &rem_in.sin_addr,
+		    ntohs(rem_in.sin_port));
+
+	ret = sock.ops->connect(&sock, (struct sockaddr *)&rem_in,
+				ulid_size, O_NONBLOCK);
+	if (ret < 0 && ret != -EINPROGRESS) {
+		mptcp_debug("%s: MPTCP subsocket connect() failed, error %d\n",
+			    __func__, ret);
+		goto error;
+	}
+
+	sk_set_socket(sk, meta_sk->sk_socket);
+	sk->sk_wq = meta_sk->sk_wq;
+
+	return 0;
+
+error:
+	/* May happen if mptcp_add_sock fails first */
+	if (!tp->mpc) {
+		tcp_close(sk, 0);
+	} else {
+		local_bh_disable();
+		mptcp_sub_force_close(sk);
+		local_bh_enable();
+	}
+	return ret;
+}
+
+/****** IPv4-Address event handler ******/
+
+/* React on IP-addr add/rem-events */
+static int mptcp_pm_inetaddr_event(struct notifier_block *this,
+				   unsigned long event, void *ptr)
+{
+	return mptcp_pm_addr_event_handler(event, ptr, AF_INET);
+}
+
+/* React on ifup/down-events */
+static int mptcp_pm_netdev_event(struct notifier_block *this,
+				 unsigned long event, void *ptr)
+{
+	struct net_device *dev = netdev_notifier_info_to_dev(ptr);
+	struct in_device *in_dev;
+
+	if (!(event == NETDEV_UP || event == NETDEV_DOWN ||
+	      event == NETDEV_CHANGE))
+		return NOTIFY_DONE;
+
+	/* Iterate over the addresses of the interface, then we go over the
+	 * mpcb's to modify them - that way we take tk_hash_lock for a shorter
+	 * time at each iteration. - otherwise we would need to take it from the
+	 * beginning till the end.
+	 */
+	rcu_read_lock();
+	in_dev = __in_dev_get_rtnl(dev);
+
+	if (in_dev) {
+		for_primary_ifa(in_dev) {
+			mptcp_pm_inetaddr_event(NULL, event, ifa);
+		} endfor_ifa(in_dev);
+	}
+
+	rcu_read_unlock();
+	return NOTIFY_DONE;
+}
+
+void mptcp_pm_addr4_event_handler(struct in_ifaddr *ifa, unsigned long event,
+				  struct mptcp_cb *mpcb)
+{
+	int i;
+	struct sock *sk, *tmpsk;
+
+	if (ifa->ifa_scope > RT_SCOPE_LINK)
+		return;
+
+	/* Look for the address among the local addresses */
+	mptcp_for_each_bit_set(mpcb->loc4_bits, i) {
+		if (mpcb->locaddr4[i].addr.s_addr == ifa->ifa_local)
+			goto found;
+	}
+
+	/* Not yet in address-list */
+	if ((event == NETDEV_UP || event == NETDEV_CHANGE) &&
+	    netif_running(ifa->ifa_dev->dev) &&
+	    !(ifa->ifa_dev->dev->flags & IFF_NOMULTIPATH)) {
+		i = __mptcp_find_free_index(mpcb->loc4_bits, 0, mpcb->next_v4_index);
+		if (i < 0) {
+			mptcp_debug("MPTCP_PM: NETDEV_UP Reached max number of local IPv4 addresses: %d\n",
+				    MPTCP_MAX_ADDR);
+			return;
+		}
+
+		/* update this mpcb */
+		mpcb->locaddr4[i].addr.s_addr = ifa->ifa_local;
+		mpcb->locaddr4[i].id = i;
+		mpcb->loc4_bits |= (1 << i);
+		mpcb->next_v4_index = i + 1;
+		/* re-send addresses */
+		mptcp_v4_send_add_addr(i, mpcb);
+		/* re-evaluate paths */
+		mptcp_create_subflows(mpcb->meta_sk);
+	}
+	return;
+found:
+	/* Address already in list. Reactivate/Deactivate the
+	 * concerned paths.
+	 */
+	mptcp_for_each_sk_safe(mpcb, sk, tmpsk) {
+		struct tcp_sock *tp = tcp_sk(sk);
+		if (sk->sk_family != AF_INET ||
+		    inet_sk(sk)->inet_saddr != ifa->ifa_local)
+			continue;
+
+		if (event == NETDEV_DOWN ||
+		    (ifa->ifa_dev->dev->flags & IFF_NOMULTIPATH)) {
+			mptcp_reinject_data(sk, 0);
+			mptcp_sub_force_close(sk);
+		} else if (event == NETDEV_CHANGE) {
+			int new_low_prio = (ifa->ifa_dev->dev->flags & IFF_MPBACKUP) ?
+						1 : 0;
+			if (new_low_prio != tp->mptcp->low_prio)
+				tp->mptcp->send_mp_prio = 1;
+			tp->mptcp->low_prio = new_low_prio;
+		}
+	}
+
+	if (event == NETDEV_DOWN ||
+	    (ifa->ifa_dev->dev->flags & IFF_NOMULTIPATH)) {
+		mpcb->loc4_bits &= ~(1 << i);
+
+		/* Force sending directly the REMOVE_ADDR option */
+		mpcb->remove_addrs |= (1 << mpcb->locaddr4[i].id);
+		sk = mptcp_select_ack_sock(mpcb->meta_sk, 0);
+		if (sk)
+			tcp_send_ack(sk);
+
+		mptcp_for_each_bit_set(mpcb->rem4_bits, i)
+			mpcb->remaddr4[i].bitfield &= mpcb->loc4_bits;
+	}
+}
+
+/* Send ADD_ADDR for loc_id on all available subflows */
+void mptcp_v4_send_add_addr(int loc_id, struct mptcp_cb *mpcb)
+{
+	struct tcp_sock *tp;
+
+	mptcp_for_each_tp(mpcb, tp)
+		tp->mptcp->add_addr4 |= (1 << loc_id);
+}
+
+static struct notifier_block mptcp_pm_inetaddr_notifier = {
+		.notifier_call = mptcp_pm_inetaddr_event,
+};
+
+static struct notifier_block mptcp_pm_netdev_notifier = {
+		.notifier_call = mptcp_pm_netdev_event,
+};
+
+/****** End of IPv4-Address event handler ******/
+
+/* General initialization of IPv4 for MPTCP */
+int mptcp_pm_v4_init(void)
+{
+	int ret;
+	struct request_sock_ops *ops = &mptcp_request_sock_ops;
+
+	ops->slab_name = kasprintf(GFP_KERNEL, "request_sock_%s", "MPTCP");
+	if (ops->slab_name == NULL) {
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	ops->slab = kmem_cache_create(ops->slab_name, ops->obj_size, 0,
+				      SLAB_HWCACHE_ALIGN, NULL);
+
+	if (ops->slab == NULL) {
+		ret =  -ENOMEM;
+		goto err_reqsk_create;
+	}
+
+	ret = register_inetaddr_notifier(&mptcp_pm_inetaddr_notifier);
+	if (ret)
+		goto err_reg_inetaddr;
+	ret = register_netdevice_notifier(&mptcp_pm_netdev_notifier);
+	if (ret)
+		goto err_reg_netdev;
+
+out:
+	return ret;
+
+err_reg_netdev:
+	unregister_inetaddr_notifier(&mptcp_pm_inetaddr_notifier);
+err_reg_inetaddr:
+	kmem_cache_destroy(ops->slab);
+err_reqsk_create:
+	kfree(ops->slab_name);
+	ops->slab_name = NULL;
+	goto out;
+}
+
+void mptcp_pm_v4_undo(void)
+{
+	unregister_inetaddr_notifier(&mptcp_pm_inetaddr_notifier);
+	unregister_netdevice_notifier(&mptcp_pm_netdev_notifier);
+	kmem_cache_destroy(mptcp_request_sock_ops.slab);
+	kfree(mptcp_request_sock_ops.slab_name);
+}
+
+
diff -Naur a/net/mptcp/mptcp_ipv6.c b/net/mptcp/mptcp_ipv6.c
--- a/net/mptcp/mptcp_ipv6.c	1970-01-01 01:00:00.000000000 +0100
+++ b/net/mptcp/mptcp_ipv6.c	2013-10-06 18:27:38.448685013 +0200
@@ -0,0 +1,1008 @@
+/*
+ *	MPTCP implementation - IPv6-specific functions
+ *
+ *	Initial Design & Implementation:
+ *	Sébastien Barré <[e-mail]>
+ *
+ *	Current Maintainer:
+ *	Jaakko Korkeaniemi <[e-mail]>
+ *
+ *	Additional authors:
+ *	Jaakko Korkeaniemi <[e-mail]>
+ *	Gregory Detal <[e-mail]>
+ *	Fabien Duchêne <[e-mail]>
+ *	Andreas Seelinger <[e-mail]>
+ *	Lavkesh Lahngir <[e-mail]>
+ *	Andreas Ripke <[e-mail]>
+ *	Vlad Dogaru <[e-mail]>
+ *	Octavian Purdila <[e-mail]>
+ *	John Ronan <[e-mail]>
+ *	Catalin Nicutar <[e-mail]>
+ *	Brandon Heller <[e-mail]>
+ *
+ *
+ *	This program is free software; you can redistribute it and/or
+ *      modify it under the terms of the GNU General Public License
+ *      as published by the Free Software Foundation; either version
+ *      2 of the License, or (at your option) any later version.
+ */
+
+#include <linux/export.h>
+#include <linux/in6.h>
+#include <linux/kernel.h>
+
+#include <net/addrconf.h>
+#include <net/flow.h>
+#include <net/inet6_connection_sock.h>
+#include <net/inet6_hashtables.h>
+#include <net/inet_common.h>
+#include <net/ipv6.h>
+#include <net/ip6_checksum.h>
+#include <net/ip6_route.h>
+#include <net/mptcp.h>
+#include <net/mptcp_pm.h>
+#include <net/mptcp_v6.h>
+#include <net/tcp.h>
+#include <net/transp_v6.h>
+
+static int mptcp_v6v4_send_synack(struct sock *meta_sk, struct request_sock *req,
+				  u16 queue_mapping);
+
+__u32 mptcp_v6_get_nonce(const __be32 *saddr, const __be32 *daddr,
+			 __be16 sport, __be16 dport, u32 seq)
+{
+	u32 secret[MD5_MESSAGE_BYTES / 4];
+	u32 hash[MD5_DIGEST_WORDS];
+	u32 i;
+
+	memcpy(hash, saddr, 16);
+	for (i = 0; i < 4; i++)
+		secret[i] = mptcp_secret[i] + (__force u32)daddr[i];
+	secret[4] = mptcp_secret[4] +
+		    (((__force u16)sport << 16) + (__force u16)dport);
+	secret[5] = seq;
+	for (i = 6; i < MD5_MESSAGE_BYTES / 4; i++)
+		secret[i] = mptcp_secret[i];
+
+	md5_transform(hash, secret);
+
+	return hash[0];
+}
+
+u64 mptcp_v6_get_key(const __be32 *saddr, const __be32 *daddr,
+		     __be16 sport, __be16 dport)
+{
+	u32 secret[MD5_MESSAGE_BYTES / 4];
+	u32 hash[MD5_DIGEST_WORDS];
+	u32 i;
+
+	memcpy(hash, saddr, 16);
+	for (i = 0; i < 4; i++)
+		secret[i] = mptcp_secret[i] + (__force u32)daddr[i];
+	secret[4] = mptcp_secret[4] +
+		    (((__force u16)sport << 16) + (__force u16)dport);
+	secret[5] = mptcp_key_seed++;
+	for (i = 5; i < MD5_MESSAGE_BYTES / 4; i++)
+		secret[i] = mptcp_secret[i];
+
+	md5_transform(hash, secret);
+
+	return *((u64 *)hash);
+}
+
+static void mptcp_v6_reqsk_destructor(struct request_sock *req)
+{
+	mptcp_reqsk_destructor(req);
+
+	tcp_v6_reqsk_destructor(req);
+}
+
+/* Similar to tcp_v6_rtx_synack */
+static int mptcp_v6_rtx_synack(struct sock *meta_sk, struct request_sock *req)
+{
+	if (meta_sk->sk_family == AF_INET6)
+		return tcp_v6_rtx_synack(meta_sk, req);
+
+	TCP_INC_STATS_BH(sock_net(meta_sk), TCP_MIB_RETRANSSEGS);
+	return mptcp_v6v4_send_synack(meta_sk, req, 0);
+}
+
+/* Similar to tcp6_request_sock_ops */
+struct request_sock_ops mptcp6_request_sock_ops __read_mostly = {
+	.family		=	AF_INET6,
+	.obj_size	=	sizeof(struct mptcp6_request_sock),
+	.rtx_syn_ack	=	mptcp_v6_rtx_synack,
+	.send_ack	=	tcp_v6_reqsk_send_ack,
+	.destructor	=	mptcp_v6_reqsk_destructor,
+	.send_reset	=	tcp_v6_send_reset,
+	.syn_ack_timeout =	tcp_syn_ack_timeout,
+};
+
+static void mptcp_v6_reqsk_queue_hash_add(struct sock *meta_sk,
+					  struct request_sock *req,
+					  unsigned long timeout)
+{
+	const u32 h = inet6_synq_hash(&inet6_rsk(req)->rmt_addr,
+				      inet_rsk(req)->rmt_port,
+				      0, MPTCP_HASH_SIZE);
+
+	inet6_csk_reqsk_queue_hash_add(meta_sk, req, timeout);
+
+	spin_lock(&mptcp_reqsk_hlock);
+	list_add(&mptcp_rsk(req)->collide_tuple, &mptcp_reqsk_htb[h]);
+	spin_unlock(&mptcp_reqsk_hlock);
+}
+
+/* Similar to tcp_v6_send_synack
+ *
+ * The meta-socket is IPv4, but a new subsocket is IPv6
+ */
+static int mptcp_v6v4_send_synack(struct sock *meta_sk, struct request_sock *req,
+				  u16 queue_mapping)
+{
+	struct inet6_request_sock *treq = inet6_rsk(req);
+	struct sk_buff *skb;
+	struct flowi6 fl6;
+	struct dst_entry *dst;
+	int err;
+
+	memset(&fl6, 0, sizeof(fl6));
+	fl6.flowi6_proto = IPPROTO_TCP;
+	fl6.daddr = treq->rmt_addr;
+	fl6.saddr = treq->loc_addr;
+	fl6.flowlabel = 0;
+	fl6.flowi6_oif = treq->iif;
+	fl6.flowi6_mark = meta_sk->sk_mark;
+	fl6.fl6_dport = inet_rsk(req)->rmt_port;
+	fl6.fl6_sport = inet_rsk(req)->loc_port;
+	security_req_classify_flow(req, flowi6_to_flowi(&fl6));
+
+	dst = ip6_dst_lookup_flow(meta_sk, &fl6, NULL, false);
+	if (IS_ERR(dst)) {
+		err = PTR_ERR(dst);
+		return err;
+	}
+	skb = tcp_make_synack(meta_sk, dst, req, NULL);
+	err = -ENOMEM;
+	if (skb) {
+		__tcp_v6_send_check(skb, &treq->loc_addr, &treq->rmt_addr);
+
+		fl6.daddr = treq->rmt_addr;
+		skb_set_queue_mapping(skb, queue_mapping);
+		err = ip6_xmit(meta_sk, skb, &fl6, NULL, 0);
+		err = net_xmit_eval(err);
+	}
+
+	return err;
+}
+
+/* Similar to tcp_v6_syn_recv_sock
+ *
+ * The meta-socket is IPv4, but a new subsocket is IPv6
+ */
+struct sock *mptcp_v6v4_syn_recv_sock(struct sock *meta_sk, struct sk_buff *skb,
+				      struct request_sock *req,
+				      struct dst_entry *dst)
+{
+	struct inet6_request_sock *treq;
+	struct ipv6_pinfo *newnp;
+	struct tcp6_sock *newtcp6sk;
+	struct inet_sock *newinet;
+	struct tcp_sock *newtp;
+	struct sock *newsk;
+
+	treq = inet6_rsk(req);
+
+	if (sk_acceptq_is_full(meta_sk))
+		goto out_overflow;
+
+	if (!dst) {
+		/* This code is similar to inet6_csk_route_req, but as we
+		 * don't have a np-pointer in the meta, we have to do it
+		 * manually.
+		 */
+		struct flowi6 fl6;
+
+		memset(&fl6, 0, sizeof(fl6));
+		fl6.flowi6_proto = IPPROTO_TCP;
+		fl6.daddr = treq->rmt_addr;
+		fl6.saddr = treq->loc_addr;
+		fl6.flowi6_oif = meta_sk->sk_bound_dev_if;
+		fl6.flowi6_mark = meta_sk->sk_mark;
+		fl6.fl6_dport = inet_rsk(req)->rmt_port;
+		fl6.fl6_sport = inet_rsk(req)->loc_port;
+		security_req_classify_flow(req, flowi6_to_flowi(&fl6));
+
+		dst = ip6_dst_lookup_flow(meta_sk, &fl6, NULL, false);
+		if (IS_ERR(dst))
+			goto out;
+	}
+
+	newsk = tcp_create_openreq_child(meta_sk, req, skb);
+	if (newsk == NULL)
+		goto out_nonewsk;
+
+	newtcp6sk = (struct tcp6_sock *)newsk;
+	inet_sk(newsk)->pinet6 = &newtcp6sk->inet6;
+
+	/*
+	 * No need to charge this sock to the relevant IPv6 refcnt debug socks
+	 * count here, tcp_create_openreq_child now does this for us, see the
+	 * comment in that function for the gory details. -acme
+	 */
+
+	newsk->sk_gso_type = SKB_GSO_TCPV6;
+	__ip6_dst_store(newsk, dst, NULL, NULL);
+	inet6_sk_rx_dst_set(newsk, skb);
+
+	newtp = tcp_sk(newsk);
+	newinet = inet_sk(newsk);
+	newnp = inet6_sk(newsk);
+
+	newnp->daddr = treq->rmt_addr;
+	newnp->saddr = treq->loc_addr;
+	newnp->rcv_saddr = treq->loc_addr;
+	newsk->sk_bound_dev_if = treq->iif;
+
+	/* Now IPv6 options...
+
+	   First: no IPv4 options.
+	 */
+	newinet->inet_opt = NULL;
+	newnp->ipv6_ac_list = NULL;
+	newnp->ipv6_fl_list = NULL;
+	newnp->rxopt.all = 0;
+
+	/* Clone pktoptions received with SYN */
+	newnp->pktoptions = NULL;
+	if (treq->pktopts != NULL) {
+		newnp->pktoptions = skb_clone(treq->pktopts,
+					      sk_gfp_atomic(meta_sk, GFP_ATOMIC));
+		consume_skb(treq->pktopts);
+		treq->pktopts = NULL;
+		if (newnp->pktoptions)
+			skb_set_owner_r(newnp->pktoptions, newsk);
+	}
+	newnp->opt	  = NULL;
+	newnp->mcast_oif  = inet6_iif(skb);
+	newnp->mcast_hops = ipv6_hdr(skb)->hop_limit;
+	newnp->rcv_tclass = ipv6_get_dsfield(ipv6_hdr(skb));
+
+	/* Initialization copied from inet6_create - normally this should have
+	 * been handled by the memcpy as in tcp_v6_syn_recv_sock
+	 */
+	newnp->hop_limit  = -1;
+	newnp->mc_loop	  = 1;
+	newnp->pmtudisc	  = IPV6_PMTUDISC_WANT;
+	(void)xchg(&newnp->rxpmtu, NULL);
+
+	inet_csk(newsk)->icsk_ext_hdr_len = 0;
+
+	tcp_mtup_init(newsk);
+	tcp_sync_mss(newsk, dst_mtu(dst));
+	newtp->advmss = dst_metric_advmss(dst);
+	if (tcp_sk(meta_sk)->rx_opt.user_mss &&
+	    tcp_sk(meta_sk)->rx_opt.user_mss < newtp->advmss)
+		newtp->advmss = tcp_sk(meta_sk)->rx_opt.user_mss;
+
+	tcp_initialize_rcv_mss(newsk);
+	tcp_synack_rtt_meas(newsk, req);
+	newtp->total_retrans = req->num_retrans;
+
+	newinet->inet_daddr = LOOPBACK4_IPV6;
+	newinet->inet_saddr = LOOPBACK4_IPV6;
+	newinet->inet_rcv_saddr = LOOPBACK4_IPV6;
+
+	if (__inet_inherit_port(meta_sk, newsk) < 0) {
+		inet_csk_prepare_forced_close(newsk);
+		tcp_done(newsk);
+		goto out;
+	}
+	__inet6_hash(newsk, NULL);
+
+	return newsk;
+
+out_overflow:
+	NET_INC_STATS_BH(sock_net(meta_sk), LINUX_MIB_LISTENOVERFLOWS);
+out_nonewsk:
+	dst_release(dst);
+out:
+	NET_INC_STATS_BH(sock_net(meta_sk), LINUX_MIB_LISTENDROPS);
+	return NULL;
+}
+
+/* Similar to tcp_v6_conn_request */
+static void mptcp_v6_join_request(struct sock *meta_sk, struct sk_buff *skb)
+{
+	struct mptcp_cb *mpcb = tcp_sk(meta_sk)->mpcb;
+	struct tcp_options_received tmp_opt;
+	struct mptcp_options_received mopt;
+	struct ipv6_pinfo *np = inet6_sk(meta_sk);
+	struct request_sock *req;
+	struct inet6_request_sock *treq;
+	struct mptcp_request_sock *mtreq;
+	u8 mptcp_hash_mac[20];
+	__u32 isn = TCP_SKB_CB(skb)->when;
+	struct dst_entry *dst = NULL;
+	struct flowi6 fl6;
+	int want_cookie = 0;
+
+	tcp_clear_options(&tmp_opt);
+	mptcp_init_mp_opt(&mopt);
+	tmp_opt.mss_clamp = TCP_MSS_DEFAULT;
+	tmp_opt.user_mss  = tcp_sk(meta_sk)->rx_opt.user_mss;
+	tcp_parse_options(skb, &tmp_opt, &mopt, 0, NULL);
+
+	req = inet6_reqsk_alloc(&mptcp6_request_sock_ops);
+	if (!req)
+		return;
+
+	tmp_opt.tstamp_ok = tmp_opt.saw_tstamp;
+	tcp_openreq_init(req, &tmp_opt, skb);
+
+	treq = inet6_rsk(req);
+	treq->rmt_addr = ipv6_hdr(skb)->saddr;
+	treq->loc_addr = ipv6_hdr(skb)->daddr;
+
+	if (!want_cookie || tmp_opt.tstamp_ok)
+		TCP_ECN_create_request(req, skb, sock_net(meta_sk));
+
+	treq->iif = meta_sk->sk_bound_dev_if;
+
+	/* So that link locals have meaning */
+	if (!meta_sk->sk_bound_dev_if &&
+	    ipv6_addr_type(&treq->rmt_addr) & IPV6_ADDR_LINKLOCAL)
+		treq->iif = inet6_iif(skb);
+
+	if (!isn) {
+		if (meta_sk->sk_family == AF_INET6 &&
+		    (ipv6_opt_accepted(meta_sk, skb) ||
+		    np->rxopt.bits.rxinfo || np->rxopt.bits.rxoinfo ||
+		    np->rxopt.bits.rxhlim || np->rxopt.bits.rxohlim)) {
+			atomic_inc(&skb->users);
+			treq->pktopts = skb;
+		}
+
+		/* VJ's idea. We save last timestamp seen
+		 * from the destination in peer table, when entering
+		 * state TIME-WAIT, and check against it before
+		 * accepting new connection request.
+		 *
+		 * If "isn" is not zero, this request hit alive
+		 * timewait bucket, so that all the necessary checks
+		 * are made in the function processing timewait state.
+		 */
+		if (tmp_opt.saw_tstamp &&
+		    tcp_death_row.sysctl_tw_recycle &&
+		    (dst = inet6_csk_route_req(meta_sk, &fl6, req)) != NULL) {
+			if (!tcp_peer_is_proven(req, dst, true)) {
+				NET_INC_STATS_BH(sock_net(meta_sk), LINUX_MIB_PAWSPASSIVEREJECTED);
+				goto drop_and_release;
+			}
+		}
+		/* Kill the following clause, if you dislike this way. */
+		else if (!sysctl_tcp_syncookies &&
+			 (sysctl_max_syn_backlog - inet_csk_reqsk_queue_len(meta_sk) <
+			  (sysctl_max_syn_backlog >> 2)) &&
+			 !tcp_peer_is_proven(req, dst, false)) {
+			/* Without syncookies last quarter of
+			 * backlog is filled with destinations,
+			 * proven to be alive.
+			 * It means that we continue to communicate
+			 * to destinations, already remembered
+			 * to the moment of synflood.
+			 */
+			LIMIT_NETDEBUG(KERN_DEBUG "TCP: drop open request from %pI6/%u\n",
+				       &treq->rmt_addr, ntohs(tcp_hdr(skb)->source));
+			goto drop_and_release;
+		}
+
+		isn = tcp_v6_init_sequence(skb);
+	}
+
+	tcp_rsk(req)->snt_isn = isn;
+	tcp_rsk(req)->snt_synack = tcp_time_stamp;
+
+	mtreq = mptcp_rsk(req);
+	mtreq->mpcb = mpcb;
+	INIT_LIST_HEAD(&mtreq->collide_tuple);
+	mtreq->mptcp_rem_nonce = mopt.mptcp_recv_nonce;
+	mtreq->mptcp_rem_key = mpcb->mptcp_rem_key;
+	mtreq->mptcp_loc_key = mpcb->mptcp_loc_key;
+	mtreq->mptcp_loc_nonce = mptcp_v6_get_nonce(ipv6_hdr(skb)->daddr.s6_addr32,
+						    ipv6_hdr(skb)->saddr.s6_addr32,
+						    tcp_hdr(skb)->dest,
+						    tcp_hdr(skb)->source, isn);
+	mptcp_hmac_sha1((u8 *)&mtreq->mptcp_loc_key,
+			(u8 *)&mtreq->mptcp_rem_key,
+			(u8 *)&mtreq->mptcp_loc_nonce,
+			(u8 *)&mtreq->mptcp_rem_nonce, (u32 *)mptcp_hash_mac);
+	mtreq->mptcp_hash_tmac = *(u64 *)mptcp_hash_mac;
+	mtreq->rem_id = mopt.rem_id;
+	mtreq->low_prio = mopt.low_prio;
+	tcp_rsk(req)->saw_mpc = 1;
+
+	if (meta_sk->sk_family == AF_INET6) {
+		if (tcp_v6_send_synack(meta_sk, dst, &fl6, req,
+				       skb_get_queue_mapping(skb)))
+			goto drop_and_free;
+	} else {
+		if (mptcp_v6v4_send_synack(meta_sk, req, skb_get_queue_mapping(skb)))
+			goto drop_and_free;
+	}
+
+	/* Adding to request queue in metasocket */
+	mptcp_v6_reqsk_queue_hash_add(meta_sk, req, TCP_TIMEOUT_INIT);
+
+	return;
+
+drop_and_release:
+	dst_release(dst);
+drop_and_free:
+	reqsk_free(req);
+	return;
+}
+
+int mptcp_v6_rem_raddress(struct mptcp_cb *mpcb, u8 id)
+{
+	int i;
+
+	for (i = 0; i < MPTCP_MAX_ADDR; i++) {
+		if (!((1 << i) & mpcb->rem6_bits))
+			continue;
+
+		if (mpcb->remaddr6[i].id == id) {
+			/* remove address from bitfield */
+			mpcb->rem6_bits &= ~(1 << i);
+
+			return 0;
+		}
+	}
+
+	return -1;
+}
+
+/* Returns -1 if there is no space anymore to store an additional
+ * address
+ */
+int mptcp_v6_add_raddress(struct mptcp_cb *mpcb, const struct in6_addr *addr,
+			  __be16 port, u8 id)
+{
+	int i;
+	struct mptcp_rem6 *rem6;
+
+	mptcp_for_each_bit_set(mpcb->rem6_bits, i) {
+		rem6 = &mpcb->remaddr6[i];
+
+		/* Address is already in the list --- continue */
+		if (rem6->id == id &&
+		    ipv6_addr_equal(&rem6->addr, addr) && rem6->port == port)
+			return 0;
+
+		/* This may be the case, when the peer is behind a NAT. He is
+		 * trying to JOIN, thus sending the JOIN with a certain ID.
+		 * However the src_addr of the IP-packet has been changed. We
+		 * update the addr in the list, because this is the address as
+		 * OUR BOX sees it.
+		 */
+		if (rem6->id == id) {
+			/* update the address */
+			mptcp_debug("%s: updating old addr: %pI6 to addr %pI6 with id:%d\n",
+				    __func__, &rem6->addr, addr, id);
+			rem6->addr = *addr;
+			rem6->port = port;
+			mpcb->list_rcvd = 1;
+			return 0;
+		}
+	}
+
+	i = mptcp_find_free_index(mpcb->rem6_bits);
+	/* Do we have already the maximum number of local/remote addresses? */
+	if (i < 0) {
+		mptcp_debug("%s: At max num of remote addresses: %d --- not adding address: %pI6\n",
+			    __func__, MPTCP_MAX_ADDR, addr);
+		return -1;
+	}
+
+	rem6 = &mpcb->remaddr6[i];
+
+	/* Address is not known yet, store it */
+	rem6->addr = *addr;
+	rem6->port = port;
+	rem6->bitfield = 0;
+	rem6->retry_bitfield = 0;
+	rem6->id = id;
+	mpcb->list_rcvd = 1;
+	mpcb->rem6_bits |= (1 << i);
+
+	return 0;
+}
+
+/* Sets the bitfield of the remote-address field
+ * local address is not set as it will disappear with the global address-list
+ */
+void mptcp_v6_set_init_addr_bit(struct mptcp_cb *mpcb,
+				const struct in6_addr *daddr)
+{
+	int i;
+	mptcp_for_each_bit_set(mpcb->rem6_bits, i) {
+		if (ipv6_addr_equal(&mpcb->remaddr6[i].addr, daddr)) {
+			/* It's the initial flow - thus local index == 0 */
+			mpcb->remaddr6[i].bitfield |= 1;
+			return;
+		}
+	}
+}
+
+int mptcp_v6_do_rcv(struct sock *meta_sk, struct sk_buff *skb)
+{
+	struct mptcp_cb *mpcb = tcp_sk(meta_sk)->mpcb;
+	struct sock *child, *rsk = NULL;
+	int ret;
+
+	if (!(TCP_SKB_CB(skb)->mptcp_flags & MPTCPHDR_JOIN)) {
+		struct tcphdr *th = tcp_hdr(skb);
+		const struct ipv6hdr *ip6h = ipv6_hdr(skb);
+		struct sock *sk;
+
+		sk = __inet6_lookup_established(sock_net(meta_sk),
+						&tcp_hashinfo,
+						&ip6h->saddr, th->source,
+						&ip6h->daddr, ntohs(th->dest),
+						inet6_iif(skb));
+
+		if (!sk) {
+			kfree_skb(skb);
+			return 0;
+		}
+		if (is_meta_sk(sk)) {
+			WARN("%s Did not find a sub-sk!\n", __func__);
+			kfree_skb(skb);
+			sock_put(sk);
+			return 0;
+		}
+
+		if (sk->sk_state == TCP_TIME_WAIT) {
+			inet_twsk_put(inet_twsk(sk));
+			kfree_skb(skb);
+			return 0;
+		}
+
+		ret = tcp_v6_do_rcv(sk, skb);
+		sock_put(sk);
+
+		return ret;
+	}
+	TCP_SKB_CB(skb)->mptcp_flags = 0;
+
+	/* Has been removed from the tk-table. Thus, no new subflows.
+	 *
+	 * Check for close-state is necessary, because we may have been closed
+	 * without passing by mptcp_close().
+	 *
+	 * When falling back, no new subflows are allowed either.
+	 */
+	if (meta_sk->sk_state == TCP_CLOSE || !tcp_sk(meta_sk)->inside_tk_table ||
+	    mpcb->infinite_mapping_rcv || mpcb->send_infinite_mapping)
+		goto reset_and_discard;
+
+	child = tcp_v6_hnd_req(meta_sk, skb);
+
+	if (!child)
+		goto discard;
+
+	if (child != meta_sk) {
+		sock_rps_save_rxhash(child, skb);
+		/* We don't call tcp_child_process here, because we hold
+		 * already the meta-sk-lock and are sure that it is not owned
+		 * by the user.
+		 */
+		ret = tcp_rcv_state_process(child, skb, tcp_hdr(skb), skb->len);
+		bh_unlock_sock(child);
+		sock_put(child);
+		if (ret) {
+			rsk = child;
+			goto reset_and_discard;
+		}
+	} else {
+		if (tcp_hdr(skb)->syn) {
+			struct mp_join *join_opt = mptcp_find_join(skb);
+			/* Currently we make two calls to mptcp_find_join(). This
+			 * can probably be optimized. */
+			if (mptcp_v6_add_raddress(mpcb,
+						  (struct in6_addr *)&ipv6_hdr(skb)->saddr,
+						  0,
+						  join_opt->addr_id) < 0)
+				goto reset_and_discard;
+			mpcb->list_rcvd = 0;
+
+			mptcp_v6_join_request(meta_sk, skb);
+			goto discard;
+		}
+		goto reset_and_discard;
+	}
+	return 0;
+
+reset_and_discard:
+	tcp_v6_send_reset(rsk, skb);
+discard:
+	kfree_skb(skb);
+	return 0;
+}
+
+/* After this, the ref count of the meta_sk associated with the request_sock
+ * is incremented. Thus it is the responsibility of the caller
+ * to call sock_put() when the reference is not needed anymore.
+ */
+struct sock *mptcp_v6_search_req(const __be16 rport, const struct in6_addr *raddr,
+				 const struct in6_addr *laddr, const struct net *net)
+{
+	struct mptcp_request_sock *mtreq;
+	struct sock *meta_sk = NULL;
+
+	spin_lock(&mptcp_reqsk_hlock);
+	list_for_each_entry(mtreq,
+			    &mptcp_reqsk_htb[inet6_synq_hash(raddr, rport, 0,
+							     MPTCP_HASH_SIZE)],
+			    collide_tuple) {
+		struct inet6_request_sock *treq = inet6_rsk(rev_mptcp_rsk(mtreq));
+		meta_sk = mtreq->mpcb->meta_sk;
+
+		if (inet_rsk(rev_mptcp_rsk(mtreq))->rmt_port == rport &&
+		    rev_mptcp_rsk(mtreq)->rsk_ops->family == AF_INET6 &&
+		    ipv6_addr_equal(&treq->rmt_addr, raddr) &&
+		    ipv6_addr_equal(&treq->loc_addr, laddr) &&
+		    net_eq(net, sock_net(meta_sk)))
+			break;
+		meta_sk = NULL;
+	}
+
+	if (meta_sk && unlikely(!atomic_inc_not_zero(&meta_sk->sk_refcnt)))
+		meta_sk = NULL;
+	spin_unlock(&mptcp_reqsk_hlock);
+
+	return meta_sk;
+}
+
+/* Create a new IPv6 subflow.
+ *
+ * We are in user-context and meta-sock-lock is hold.
+ */
+int mptcp_init6_subsockets(struct sock *meta_sk, const struct mptcp_loc6 *loc,
+			   struct mptcp_rem6 *rem)
+{
+	struct tcp_sock *tp;
+	struct sock *sk;
+	struct sockaddr_in6 loc_in, rem_in;
+	struct socket sock;
+	int ulid_size = 0, ret;
+
+	/* Don't try again - even if it fails.
+	 * There is a special case as the IPv6 address of the initial subflow
+	 * has an id = 0. The other ones have id's in the range [8, 16[.
+	 */
+	rem->bitfield |= (1 << (loc->id - min_t(u8, loc->id, MPTCP_MAX_ADDR)));
+
+	/** First, create and prepare the new socket */
+
+	sock.type = meta_sk->sk_socket->type;
+	sock.state = SS_UNCONNECTED;
+	sock.wq = meta_sk->sk_socket->wq;
+	sock.file = meta_sk->sk_socket->file;
+	sock.ops = NULL;
+
+	ret = inet6_create(sock_net(meta_sk), &sock, IPPROTO_TCP, 1);
+	if (unlikely(ret < 0)) {
+		mptcp_debug("%s inet6_create failed ret: %d\n", __func__, ret);
+		return ret;
+	}
+
+	sk = sock.sk;
+	tp = tcp_sk(sk);
+
+	/* All subsockets need the MPTCP-lock-class */
+	lockdep_set_class_and_name(&(sk)->sk_lock.slock, &meta_slock_key, "slock-AF_INET-MPTCP");
+	lockdep_init_map(&(sk)->sk_lock.dep_map, "sk_lock-AF_INET-MPTCP", &meta_key, 0);
+
+	if (mptcp_add_sock(meta_sk, sk, rem->id, GFP_KERNEL))
+		goto error;
+
+	tp->mptcp->slave_sk = 1;
+	tp->mptcp->low_prio = loc->low_prio;
+
+	/* Initializing the timer for an MPTCP subflow */
+	setup_timer(&tp->mptcp->mptcp_ack_timer, mptcp_ack_handler, (unsigned long)sk);
+
+	/** Then, connect the socket to the peer */
+
+	ulid_size = sizeof(struct sockaddr_in6);
+	loc_in.sin6_family = AF_INET6;
+	rem_in.sin6_family = AF_INET6;
+	loc_in.sin6_port = 0;
+	if (rem->port)
+		rem_in.sin6_port = rem->port;
+	else
+		rem_in.sin6_port = inet_sk(meta_sk)->inet_dport;
+	loc_in.sin6_addr = loc->addr;
+	rem_in.sin6_addr = rem->addr;
+
+	ret = sock.ops->bind(&sock, (struct sockaddr *)&loc_in, ulid_size);
+	if (ret < 0) {
+		mptcp_debug("%s: MPTCP subsocket bind()failed, error %d\n",
+			    __func__, ret);
+		goto error;
+	}
+
+	mptcp_debug("%s: token %#x pi %d src_addr:%pI6:%d dst_addr:%pI6:%d\n",
+		    __func__, tcp_sk(meta_sk)->mpcb->mptcp_loc_token,
+		    tp->mptcp->path_index, &loc_in.sin6_addr,
+		    ntohs(loc_in.sin6_port), &rem_in.sin6_addr,
+		    ntohs(rem_in.sin6_port));
+
+	ret = sock.ops->connect(&sock, (struct sockaddr *)&rem_in,
+				ulid_size, O_NONBLOCK);
+	if (ret < 0 && ret != -EINPROGRESS) {
+		mptcp_debug("%s: MPTCP subsocket connect() failed, error %d\n",
+			    __func__, ret);
+		goto error;
+	}
+
+	sk_set_socket(sk, meta_sk->sk_socket);
+	sk->sk_wq = meta_sk->sk_wq;
+
+	return 0;
+
+error:
+	/* May happen if mptcp_add_sock fails first */
+	if (!tp->mpc) {
+		tcp_close(sk, 0);
+	} else {
+		local_bh_disable();
+		mptcp_sub_force_close(sk);
+		local_bh_enable();
+	}
+	return ret;
+}
+
+struct mptcp_dad_data {
+	struct timer_list timer;
+	struct inet6_ifaddr *ifa;
+};
+
+static int mptcp_ipv6_is_in_dad_state(struct inet6_ifaddr *ifa)
+{
+	return ((ifa->flags & IFA_F_TENTATIVE) &&
+		ifa->state == INET6_IFADDR_STATE_DAD);
+}
+
+static void mptcp_dad_callback(unsigned long arg);
+static int mptcp_pm_inet6_addr_event(struct notifier_block *this,
+				     unsigned long event, void *ptr);
+
+static inline void mptcp_dad_init_timer(struct mptcp_dad_data *data,
+					struct inet6_ifaddr *ifa)
+{
+	data->ifa = ifa;
+	data->timer.data = (unsigned long)data;
+	data->timer.function = mptcp_dad_callback;
+	if (ifa->idev->cnf.rtr_solicit_delay)
+		data->timer.expires = jiffies + ifa->idev->cnf.rtr_solicit_delay;
+	else
+		data->timer.expires = jiffies + MPTCP_IPV6_DEFAULT_DAD_WAIT;
+}
+
+static void mptcp_dad_callback(unsigned long arg)
+{
+	struct mptcp_dad_data *data = (struct mptcp_dad_data *)arg;
+
+	if (mptcp_ipv6_is_in_dad_state(data->ifa)) {
+		mptcp_dad_init_timer(data, data->ifa);
+		add_timer(&data->timer);
+	} else {
+		mptcp_pm_inet6_addr_event(NULL, NETDEV_UP, data->ifa);
+		in6_ifa_put(data->ifa);
+		kfree(data);
+	}
+}
+
+static inline void mptcp_dad_setup_timer(struct inet6_ifaddr *ifa)
+{
+	struct mptcp_dad_data *data;
+
+	data = kmalloc(sizeof(*data), GFP_ATOMIC);
+
+	if (!data)
+		return;
+
+	init_timer(&data->timer);
+	mptcp_dad_init_timer(data, ifa);
+	add_timer(&data->timer);
+	in6_ifa_hold(ifa);
+}
+
+/* React on IPv6-addr add/rem-events */
+static int mptcp_pm_inet6_addr_event(struct notifier_block *this,
+				     unsigned long event, void *ptr)
+{
+	if (mptcp_ipv6_is_in_dad_state((struct inet6_ifaddr *)ptr)) {
+		mptcp_dad_setup_timer((struct inet6_ifaddr *)ptr);
+		return NOTIFY_DONE;
+	} else {
+		return mptcp_pm_addr_event_handler(event, ptr, AF_INET6);
+	}
+}
+
+/* React on ifup/down-events */
+static int mptcp_pm_v6_netdev_event(struct notifier_block *this,
+		unsigned long event, void *ptr)
+{
+	struct net_device *dev = netdev_notifier_info_to_dev(ptr);
+	struct inet6_dev *in6_dev = NULL;
+
+	if (!(event == NETDEV_UP || event == NETDEV_DOWN ||
+	      event == NETDEV_CHANGE))
+		return NOTIFY_DONE;
+
+	/* Iterate over the addresses of the interface, then we go over the
+	 * mpcb's to modify them - that way we take tk_hash_lock for a shorter
+	 * time at each iteration. - otherwise we would need to take it from the
+	 * beginning till the end.
+	 */
+	rcu_read_lock();
+	in6_dev = __in6_dev_get(dev);
+
+	if (in6_dev) {
+		struct inet6_ifaddr *ifa6;
+		list_for_each_entry(ifa6, &in6_dev->addr_list, if_list)
+				mptcp_pm_inet6_addr_event(NULL, event, ifa6);
+	}
+
+	rcu_read_unlock();
+	return NOTIFY_DONE;
+}
+
+void mptcp_pm_addr6_event_handler(struct inet6_ifaddr *ifa, unsigned long event,
+				  struct mptcp_cb *mpcb)
+{
+	int i;
+	struct sock *sk, *tmpsk;
+	int addr_type = ipv6_addr_type(&ifa->addr);
+
+	/* Checks on interface and address-type */
+	if (ifa->scope > RT_SCOPE_LINK ||
+	    addr_type == IPV6_ADDR_ANY ||
+	    (addr_type & IPV6_ADDR_LOOPBACK) ||
+	    (addr_type & IPV6_ADDR_LINKLOCAL))
+		return;
+
+	/* Look for the address among the local addresses */
+	mptcp_for_each_bit_set(mpcb->loc6_bits, i) {
+		if (ipv6_addr_equal(&mpcb->locaddr6[i].addr, &ifa->addr))
+			goto found;
+	}
+
+	/* Not yet in address-list */
+	if ((event == NETDEV_UP || event == NETDEV_CHANGE) &&
+	    netif_running(ifa->idev->dev) &&
+	    !(ifa->idev->dev->flags & IFF_NOMULTIPATH)) {
+		i = __mptcp_find_free_index(mpcb->loc6_bits, 0, mpcb->next_v6_index);
+		if (i < 0) {
+			mptcp_debug("MPTCP_PM: NETDEV_UP Reached max number of local IPv6 addresses: %d\n",
+				    MPTCP_MAX_ADDR);
+			return;
+		}
+
+		/* update this mpcb */
+		mpcb->locaddr6[i].addr = ifa->addr;
+		mpcb->locaddr6[i].id = i + MPTCP_MAX_ADDR;
+		mpcb->loc6_bits |= (1 << i);
+		mpcb->next_v6_index = i + 1;
+		/* re-send addresses */
+		mptcp_v6_send_add_addr(i, mpcb);
+		/* re-evaluate paths */
+		mptcp_create_subflows(mpcb->meta_sk);
+	}
+	return;
+found:
+	/* Address already in list. Reactivate/Deactivate the
+	 * concerned paths. */
+	mptcp_for_each_sk_safe(mpcb, sk, tmpsk) {
+		struct tcp_sock *tp = tcp_sk(sk);
+		if (sk->sk_family != AF_INET6 ||
+		    !ipv6_addr_equal(&inet6_sk(sk)->saddr, &ifa->addr))
+			continue;
+
+		if (event == NETDEV_DOWN ||
+		    (ifa->idev->dev->flags & IFF_NOMULTIPATH)) {
+			mptcp_reinject_data(sk, 0);
+			mptcp_sub_force_close(sk);
+		} else if (event == NETDEV_CHANGE) {
+			int new_low_prio = (ifa->idev->dev->flags & IFF_MPBACKUP) ?
+						1 : 0;
+			if (new_low_prio != tp->mptcp->low_prio)
+				tp->mptcp->send_mp_prio = 1;
+			tp->mptcp->low_prio = new_low_prio;
+		}
+	}
+
+	if (event == NETDEV_DOWN ||
+	    (ifa->idev->dev->flags & IFF_NOMULTIPATH)) {
+		mpcb->loc6_bits &= ~(1 << i);
+
+		/* Force sending directly the REMOVE_ADDR option */
+		mpcb->remove_addrs |= (1 << mpcb->locaddr6[i].id);
+		sk = mptcp_select_ack_sock(mpcb->meta_sk, 0);
+		if (sk)
+			tcp_send_ack(sk);
+
+		mptcp_for_each_bit_set(mpcb->rem6_bits, i)
+			mpcb->remaddr6[i].bitfield &= mpcb->loc6_bits;
+	}
+}
+
+/* Send ADD_ADDR for loc_id on all available subflows */
+void mptcp_v6_send_add_addr(int loc_id, struct mptcp_cb *mpcb)
+{
+	struct tcp_sock *tp;
+
+	mptcp_for_each_tp(mpcb, tp)
+		tp->mptcp->add_addr6 |= (1 << loc_id);
+}
+
+
+static struct notifier_block mptcp_pm_inet6_addr_notifier = {
+		.notifier_call = mptcp_pm_inet6_addr_event,
+};
+
+static struct notifier_block mptcp_pm_v6_netdev_notifier = {
+		.notifier_call = mptcp_pm_v6_netdev_event,
+};
+
+/****** End of IPv6-Address event handler ******/
+
+int mptcp_pm_v6_init(void)
+{
+	int ret;
+	struct request_sock_ops *ops = &mptcp6_request_sock_ops;
+
+	ops->slab_name = kasprintf(GFP_KERNEL, "request_sock_%s", "MPTCP6");
+	if (ops->slab_name == NULL) {
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	ops->slab = kmem_cache_create(ops->slab_name, ops->obj_size, 0,
+				      SLAB_HWCACHE_ALIGN, NULL);
+
+	if (ops->slab == NULL) {
+		ret =  -ENOMEM;
+		goto err_reqsk_create;
+	}
+
+	ret = register_inet6addr_notifier(&mptcp_pm_inet6_addr_notifier);
+	if (ret)
+		goto err_reg_inet6addr;
+	ret = register_netdevice_notifier(&mptcp_pm_v6_netdev_notifier);
+	if (ret)
+		goto err_reg_netdev6;
+
+out:
+	return ret;
+
+err_reg_netdev6:
+	unregister_inet6addr_notifier(&mptcp_pm_inet6_addr_notifier);
+err_reg_inet6addr:
+	kmem_cache_destroy(ops->slab);
+err_reqsk_create:
+	kfree(ops->slab_name);
+	ops->slab_name = NULL;
+	goto out;
+}
+
+void mptcp_pm_v6_undo(void)
+{
+	kmem_cache_destroy(mptcp6_request_sock_ops.slab);
+	kfree(mptcp6_request_sock_ops.slab_name);
+	unregister_inet6addr_notifier(&mptcp_pm_inet6_addr_notifier);
+	unregister_netdevice_notifier(&mptcp_pm_v6_netdev_notifier);
+}
diff -Naur a/net/mptcp/mptcp_ofo_queue.c b/net/mptcp/mptcp_ofo_queue.c
--- a/net/mptcp/mptcp_ofo_queue.c	1970-01-01 01:00:00.000000000 +0100
+++ b/net/mptcp/mptcp_ofo_queue.c	2013-10-06 18:26:04.509865984 +0200
@@ -0,0 +1,278 @@
+/*
+ *	MPTCP implementation - Fast algorithm for MPTCP meta-reordering
+ *
+ *	Initial Design & Implementation:
+ *	Sébastien Barré <[e-mail]>
+ *
+ *	Current Maintainer & Author:
+ *	Christoph Paasch <[e-mail]>
+ *
+ *	Additional authors:
+ *	Jaakko Korkeaniemi <[e-mail]>
+ *	Gregory Detal <[e-mail]>
+ *	Fabien Duchêne <[e-mail]>
+ *	Andreas Seelinger <[e-mail]>
+ *	Lavkesh Lahngir <[e-mail]>
+ *	Andreas Ripke <[e-mail]>
+ *	Vlad Dogaru <[e-mail]>
+ *	Octavian Purdila <[e-mail]>
+ *	John Ronan <[e-mail]>
+ *	Catalin Nicutar <[e-mail]>
+ *	Brandon Heller <[e-mail]>
+ *
+ *	This program is free software; you can redistribute it and/or
+ *      modify it under the terms of the GNU General Public License
+ *      as published by the Free Software Foundation; either version
+ *      2 of the License, or (at your option) any later version.
+ */
+
+#include <linux/skbuff.h>
+#include <linux/slab.h>
+#include <net/tcp.h>
+#include <net/mptcp.h>
+
+static void mptcp_remove_shortcuts(const struct mptcp_cb *mpcb,
+				   const struct sk_buff *skb)
+{
+	struct tcp_sock *tp;
+
+	mptcp_for_each_tp(mpcb, tp) {
+		if (tp->mptcp->shortcut_ofoqueue == skb) {
+			tp->mptcp->shortcut_ofoqueue = NULL;
+			return;
+		}
+	}
+}
+
+/* Does 'skb' fits after 'here' in the queue 'head' ?
+ * If yes, we queue it and return 1
+ */
+static int mptcp_ofo_queue_after(struct sk_buff_head *head,
+				 struct sk_buff *skb, struct sk_buff *here,
+				 struct tcp_sock *tp)
+{
+	struct sock *meta_sk = tp->meta_sk;
+	struct tcp_sock *meta_tp = tcp_sk(meta_sk);
+	u32 seq = TCP_SKB_CB(skb)->seq;
+	u32 end_seq = TCP_SKB_CB(skb)->end_seq;
+
+	/* We want to queue skb after here, thus seq >= end_seq */
+	if (before(seq, TCP_SKB_CB(here)->end_seq))
+		return 0;
+
+	if (seq == TCP_SKB_CB(here)->end_seq) {
+		bool fragstolen = false;
+
+		if (!tcp_try_coalesce(meta_sk, here, skb, &fragstolen)) {
+			__skb_queue_after(&meta_tp->out_of_order_queue, here, skb);
+			return 1;
+		} else {
+			kfree_skb_partial(skb, fragstolen);
+			return -1;
+		}
+	}
+
+	/* If here is the last one, we can always queue it */
+	if (skb_queue_is_last(head, here)) {
+		__skb_queue_after(head, here, skb);
+		return 1;
+	} else {
+		struct sk_buff *skb1 = skb_queue_next(head, here);
+		/* It's not the last one, but does it fits between 'here' and
+		 * the one after 'here' ? Thus, does end_seq <= after_here->seq
+		 */
+		if (!after(end_seq, TCP_SKB_CB(skb1)->seq)) {
+			__skb_queue_after(head, here, skb);
+			return 1;
+		}
+	}
+
+	return 0;
+}
+
+static void try_shortcut(struct sk_buff *shortcut, struct sk_buff *skb,
+			 struct sk_buff_head *head, struct tcp_sock *tp)
+{
+	struct sock *meta_sk = tp->meta_sk;
+	struct tcp_sock *tp_it, *meta_tp = tcp_sk(meta_sk);
+	struct mptcp_cb *mpcb = meta_tp->mpcb;
+	struct sk_buff *skb1, *best_shortcut = NULL;
+	u32 seq = TCP_SKB_CB(skb)->seq;
+	u32 end_seq = TCP_SKB_CB(skb)->end_seq;
+	u32 distance = 0xffffffff;
+
+	/* First, check the tp's shortcut */
+	if (!shortcut) {
+		if (skb_queue_empty(head)) {
+			__skb_queue_head(head, skb);
+			goto end;
+		}
+	} else {
+		int ret = mptcp_ofo_queue_after(head, skb, shortcut, tp);
+		/* Does the tp's shortcut is a hit? If yes, we insert. */
+
+		if (ret) {
+			skb = (ret > 0) ? skb : NULL;
+			goto end;
+		}
+	}
+
+	/* Check the shortcuts of the other subsockets. */
+	mptcp_for_each_tp(mpcb, tp_it) {
+		shortcut = tp_it->mptcp->shortcut_ofoqueue;
+		/* Can we queue it here? If yes, do so! */
+		if (shortcut) {
+			int ret = mptcp_ofo_queue_after(head, skb, shortcut, tp);
+
+			if (ret) {
+				skb = (ret > 0) ? skb : NULL;
+				goto end;
+			}
+		}
+
+		/* Could not queue it, check if we are close.
+		 * We are looking for a shortcut, close enough to seq to
+		 * set skb1 prematurely and thus improve the subsequent lookup,
+		 * which tries to find a skb1 so that skb1->seq <= seq.
+		 *
+		 * So, here we only take shortcuts, whose shortcut->seq > seq,
+		 * and minimize the distance between shortcut->seq and seq and
+		 * set best_shortcut to this one with the minimal distance.
+		 *
+		 * That way, the subsequent while-loop is shortest.
+		 */
+		if (shortcut && after(TCP_SKB_CB(shortcut)->seq, seq)) {
+			/* Are we closer than the current best shortcut? */
+			if ((u32)(seq - TCP_SKB_CB(shortcut)->seq) < distance) {
+				distance = (u32)(seq - TCP_SKB_CB(shortcut)->seq);
+				best_shortcut = shortcut;
+			}
+		}
+	}
+
+	if (best_shortcut)
+		skb1 = best_shortcut;
+	else
+		skb1 = skb_peek_tail(head);
+
+	if (seq == TCP_SKB_CB(skb1)->end_seq) {
+		bool fragstolen = false;
+
+		if (!tcp_try_coalesce(meta_sk, skb1, skb, &fragstolen)) {
+			__skb_queue_after(&meta_tp->out_of_order_queue, skb1, skb);
+		} else {
+			kfree_skb_partial(skb, fragstolen);
+			skb = NULL;
+		}
+
+		goto end;
+	}
+
+	/* Find the insertion point, starting from best_shortcut if available.
+	 *
+	 * Inspired from tcp_data_queue_ofo.
+	 */
+	while (1) {
+		/* skb1->seq <= seq */
+		if (!after(TCP_SKB_CB(skb1)->seq, seq))
+			break;
+		if (skb_queue_is_first(head, skb1)) {
+			skb1 = NULL;
+			break;
+		}
+		skb1 = skb_queue_prev(head, skb1);
+	}
+
+	/* Do skb overlap to previous one? */
+	if (skb1 && before(seq, TCP_SKB_CB(skb1)->end_seq)) {
+		if (!after(end_seq, TCP_SKB_CB(skb1)->end_seq)) {
+			/* All the bits are present. */
+			__kfree_skb(skb);
+			skb = NULL;
+			goto end;
+		}
+		if (seq == TCP_SKB_CB(skb1)->seq) {
+			if (skb_queue_is_first(head, skb1))
+				skb1 = NULL;
+			else
+				skb1 = skb_queue_prev(head, skb1);
+		}
+	}
+	if (!skb1)
+		__skb_queue_head(head, skb);
+	else
+		__skb_queue_after(head, skb1, skb);
+
+	/* And clean segments covered by new one as whole. */
+	while (!skb_queue_is_last(head, skb)) {
+		skb1 = skb_queue_next(head, skb);
+
+		if (!after(end_seq, TCP_SKB_CB(skb1)->seq))
+			break;
+
+		__skb_unlink(skb1, head);
+		mptcp_remove_shortcuts(mpcb, skb1);
+		__kfree_skb(skb1);
+	}
+
+end:
+	if (skb) {
+		skb_set_owner_r(skb, meta_sk);
+		tp->mptcp->shortcut_ofoqueue = skb;
+	}
+
+	return;
+}
+
+/**
+ * @sk: the subflow that received this skb.
+ */
+void mptcp_add_meta_ofo_queue(struct sock *meta_sk, struct sk_buff *skb,
+			      struct sock *sk)
+{
+	struct tcp_sock *tp = tcp_sk(sk);
+
+	try_shortcut(tp->mptcp->shortcut_ofoqueue, skb,
+		     &tcp_sk(meta_sk)->out_of_order_queue, tp);
+}
+
+void mptcp_ofo_queue(struct sock *meta_sk)
+{
+	struct tcp_sock *meta_tp = tcp_sk(meta_sk);
+	struct sk_buff *skb;
+
+	while ((skb = skb_peek(&meta_tp->out_of_order_queue)) != NULL) {
+		u32 old_rcv_nxt = meta_tp->rcv_nxt;
+		if (after(TCP_SKB_CB(skb)->seq, meta_tp->rcv_nxt))
+			break;
+
+		if (!after(TCP_SKB_CB(skb)->end_seq, meta_tp->rcv_nxt)) {
+			__skb_unlink(skb, &meta_tp->out_of_order_queue);
+			mptcp_remove_shortcuts(meta_tp->mpcb, skb);
+			__kfree_skb(skb);
+			continue;
+		}
+
+		__skb_unlink(skb, &meta_tp->out_of_order_queue);
+		mptcp_remove_shortcuts(meta_tp->mpcb, skb);
+
+		__skb_queue_tail(&meta_sk->sk_receive_queue, skb);
+		meta_tp->rcv_nxt = TCP_SKB_CB(skb)->end_seq;
+		mptcp_check_rcvseq_wrap(meta_tp, old_rcv_nxt);
+
+		if (tcp_hdr(skb)->fin)
+			mptcp_fin(meta_sk);
+	}
+}
+
+void mptcp_purge_ofo_queue(struct tcp_sock *meta_tp)
+{
+	struct sk_buff_head *head = &meta_tp->out_of_order_queue;
+	struct sk_buff *skb, *tmp;
+
+	skb_queue_walk_safe(head, skb, tmp) {
+		__skb_unlink(skb, head);
+		mptcp_remove_shortcuts(meta_tp->mpcb, skb);
+		kfree_skb(skb);
+	}
+}
diff -Naur a/net/mptcp/mptcp_olia.c b/net/mptcp/mptcp_olia.c
--- a/net/mptcp/mptcp_olia.c	1970-01-01 01:00:00.000000000 +0100
+++ b/net/mptcp/mptcp_olia.c	2013-10-06 18:26:04.509865984 +0200
@@ -0,0 +1,314 @@
+/*
+ * MPTCP implementation - OPPORTUNISTIC LINKED INCREASES CONGESTION CONTROL:
+ *
+ * Algorithm design:
+ * Ramin Khalili <[e-mail]>
+ * Nicolas Gast <[e-mail]>
+ * Jean-Yves Le Boudec <[e-mail]>
+ *
+ * Implementation:
+ * Ramin Khalili <[e-mail]>
+ *
+ * Ported to the official MPTCP-kernel:
+ * Christoph Paasch <[e-mail]>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+
+#include <net/tcp.h>
+#include <net/mptcp.h>
+
+#include <linux/module.h>
+
+static int scale = 10;
+
+struct mptcp_olia {
+	u32	mptcp_loss1;
+	u32	mptcp_loss2;
+	u32	mptcp_loss3;
+	int	epsilon_num;
+	u32	epsilon_den;
+	int	mptcp_snd_cwnd_cnt;
+};
+
+static inline int mptcp_olia_sk_can_send(const struct sock *sk)
+{
+	return mptcp_sk_can_send(sk) && tcp_sk(sk)->srtt;
+}
+
+static inline u64 mptcp_olia_scale(u64 val, int scale)
+{
+	return (u64) val << scale;
+}
+
+/* take care of artificially inflate (see RFC5681)
+ * of cwnd during fast-retransmit phase
+ */
+static u32 mptcp_get_crt_cwnd(struct sock *sk)
+{
+	struct inet_connection_sock *icsk = inet_csk(sk);
+
+	if (icsk->icsk_ca_state == TCP_CA_Recovery)
+		return tcp_sk(sk)->snd_ssthresh;
+	else
+		return tcp_sk(sk)->snd_cwnd;
+}
+
+/* return the dominator of the first term of  the increasing term */
+static u64 mptcp_get_rate(struct mptcp_cb *mpcb , u32 path_rtt)
+{
+	struct sock *sk;
+	u64 rate = 1; /* We have to avoid a zero-rate because it is used as a divisor */
+
+	mptcp_for_each_sk(mpcb, sk) {
+		struct tcp_sock *tp = tcp_sk(sk);
+		u64 scaled_num;
+		u32 tmp_cwnd;
+
+		if (!mptcp_olia_sk_can_send(sk))
+			continue;
+
+		tmp_cwnd = mptcp_get_crt_cwnd(sk);
+		scaled_num = mptcp_olia_scale(tmp_cwnd, scale) * path_rtt;
+		rate += div_u64(scaled_num , tp->srtt);
+	}
+	rate *= rate;
+	return rate;
+}
+
+/* find the maximum cwnd, used to find set M */
+static u32 mptcp_get_max_cwnd(struct mptcp_cb *mpcb)
+{
+	struct sock *sk;
+	u32 best_cwnd = 0;
+
+	mptcp_for_each_sk(mpcb, sk) {
+		u32 tmp_cwnd;
+
+		if (!mptcp_olia_sk_can_send(sk))
+			continue;
+
+		tmp_cwnd = mptcp_get_crt_cwnd(sk);
+		if (tmp_cwnd > best_cwnd)
+			best_cwnd = tmp_cwnd;
+	}
+	return best_cwnd;
+}
+
+static void mptcp_get_epsilon(struct mptcp_cb *mpcb)
+{
+	struct mptcp_olia *ca;
+	struct tcp_sock *tp;
+	struct sock *sk;
+	u64 tmp_int, tmp_rtt, best_int = 0, best_rtt = 1;
+	u32 max_cwnd = 1, best_cwnd = 1, tmp_cwnd;
+	u8 M = 0, B_not_M = 0;
+
+	/* TODO - integrate this in the following loop - we just want to iterate once */
+
+	max_cwnd = mptcp_get_max_cwnd(mpcb);
+
+	/* find the best path */
+	mptcp_for_each_sk(mpcb, sk) {
+		tp = tcp_sk(sk);
+		ca = inet_csk_ca(sk);
+
+		if (!mptcp_olia_sk_can_send(sk))
+			continue;
+
+		tmp_rtt = tp->srtt * tp->srtt;
+		/* TODO - check here and rename variables */
+		tmp_int = max(ca->mptcp_loss3 - ca->mptcp_loss2,
+			      ca->mptcp_loss2 - ca->mptcp_loss1);
+
+		tmp_cwnd = mptcp_get_crt_cwnd(sk);
+		if (tmp_int * best_rtt >= best_int * tmp_rtt) {
+			best_rtt = tmp_rtt;
+			best_int = tmp_int;
+			best_cwnd = tmp_cwnd;
+		}
+	}
+
+	/* TODO - integrate this here in mptcp_get_max_cwnd and in the previous loop */
+	/* find the size of M and B_not_M */
+	mptcp_for_each_sk(mpcb, sk) {
+		tp = tcp_sk(sk);
+		ca = inet_csk_ca(sk);
+
+		if (!mptcp_olia_sk_can_send(sk))
+			continue;
+
+		tmp_cwnd = mptcp_get_crt_cwnd(sk);
+		if (tmp_cwnd == max_cwnd) {
+			M++;
+		} else {
+			tmp_rtt = tp->srtt * tp->srtt;
+			tmp_int = max(ca->mptcp_loss3 - ca->mptcp_loss2,
+				      ca->mptcp_loss2 - ca->mptcp_loss1);
+
+			if (tmp_int * best_rtt == best_int * tmp_rtt)
+				B_not_M++;
+		}
+	}
+
+	/* check if the path is in M or B_not_M and set the value of epsilon accordingly */
+	mptcp_for_each_sk(mpcb, sk) {
+		tp = tcp_sk(sk);
+		ca = inet_csk_ca(sk);
+
+		if (!mptcp_olia_sk_can_send(sk))
+			continue;
+
+		if (B_not_M == 0) {
+			ca->epsilon_num = 0;
+			ca->epsilon_den = 1;
+		} else {
+			tmp_rtt = tp->srtt * tp->srtt;
+			tmp_int = max(ca->mptcp_loss3 - ca->mptcp_loss2,
+				      ca->mptcp_loss2 - ca->mptcp_loss1);
+			tmp_cwnd = mptcp_get_crt_cwnd(sk);
+
+			if (tmp_cwnd < max_cwnd &&
+			    tmp_int * best_rtt == best_int * tmp_rtt){
+				ca->epsilon_num = 1;
+				ca->epsilon_den = mpcb->cnt_established * B_not_M;
+			} else if (tmp_cwnd == max_cwnd) {
+				ca->epsilon_num = -1;
+				ca->epsilon_den = mpcb->cnt_established  * M;
+			} else {
+				ca->epsilon_num = 0;
+				ca->epsilon_den = 1;
+			}
+		}
+	}
+
+}
+
+/* setting the initial values */
+static void mptcp_olia_init(struct sock *sk)
+{
+	struct tcp_sock *tp = tcp_sk(sk);
+	struct mptcp_olia *ca = inet_csk_ca(sk);
+
+	if (tp->mpc) {
+		ca->mptcp_loss1 = tp->snd_una;
+		ca->mptcp_loss2 = tp->snd_una;
+		ca->mptcp_loss3 = tp->snd_una;
+		ca->mptcp_snd_cwnd_cnt = 0;
+		ca->epsilon_num = 0;
+		ca->epsilon_den = 1;
+	}
+}
+
+/* updating inter-loss distance and ssthresh */
+static void mptcp_olia_set_state(struct sock *sk, u8 new_state)
+{
+	if (!tcp_sk(sk)->mpc)
+		return;
+
+	if (new_state == TCP_CA_Loss ||
+	    new_state == TCP_CA_Recovery || new_state == TCP_CA_CWR) {
+		struct mptcp_olia *ca = inet_csk_ca(sk);
+
+		if (ca->mptcp_loss3 != ca->mptcp_loss2 &&
+		    !inet_csk(sk)->icsk_retransmits) {
+			ca->mptcp_loss1 = ca->mptcp_loss2;
+			ca->mptcp_loss2 = ca->mptcp_loss3;
+		}
+	}
+
+}
+
+/* main algorithm */
+static void mptcp_olia_cong_avoid(struct sock *sk, u32 ack, u32 in_flight)
+{
+	struct tcp_sock *tp = tcp_sk(sk);
+	struct mptcp_olia *ca = inet_csk_ca(sk);
+	struct mptcp_cb *mpcb = tp->mpcb;
+
+	u64 inc_num, inc_den, rate, cwnd_scaled;
+
+	if (!tp->mpc) {
+		tcp_reno_cong_avoid(sk, ack, in_flight);
+		return;
+	}
+
+	ca->mptcp_loss3 = tp->snd_una;
+
+	if (!tcp_is_cwnd_limited(sk, in_flight))
+		return;
+
+	/* slow start if it is in the safe area */
+	if (tp->snd_cwnd <= tp->snd_ssthresh) {
+		tcp_slow_start(tp);
+		return;
+	}
+
+	mptcp_get_epsilon(mpcb);
+	rate = mptcp_get_rate(mpcb, tp->srtt);
+	cwnd_scaled = mptcp_olia_scale(tp->snd_cwnd, scale);
+	inc_den = ca->epsilon_den * tp->snd_cwnd * rate ? : 1;
+
+	/* calculate the increasing term, scaling is used to reduce the rounding effect */
+	if (ca->epsilon_num == -1) {
+		if (ca->epsilon_den * cwnd_scaled * cwnd_scaled < rate) {
+			inc_num = rate - ca->epsilon_den *
+				cwnd_scaled * cwnd_scaled;
+			ca->mptcp_snd_cwnd_cnt -= div64_u64(
+			    mptcp_olia_scale(inc_num , scale) , inc_den);
+		} else {
+			inc_num = ca->epsilon_den *
+			    cwnd_scaled * cwnd_scaled - rate;
+			ca->mptcp_snd_cwnd_cnt += div64_u64(
+			    mptcp_olia_scale(inc_num , scale) , inc_den);
+		}
+	} else {
+		inc_num = ca->epsilon_num * rate +
+		    ca->epsilon_den * cwnd_scaled * cwnd_scaled;
+		ca->mptcp_snd_cwnd_cnt += div64_u64(
+		    mptcp_olia_scale(inc_num , scale) , inc_den);
+	}
+
+
+	if (ca->mptcp_snd_cwnd_cnt >= (1 << scale) - 1) {
+		if (tp->snd_cwnd < tp->snd_cwnd_clamp)
+			tp->snd_cwnd++;
+		ca->mptcp_snd_cwnd_cnt = 0;
+	} else if (ca->mptcp_snd_cwnd_cnt <= 0 - (1 << scale) + 1) {
+		tp->snd_cwnd = max((int) 1 , (int) tp->snd_cwnd - 1);
+		ca->mptcp_snd_cwnd_cnt = 0;
+	}
+}
+
+static struct tcp_congestion_ops mptcp_olia = {
+	.init		= mptcp_olia_init,
+	.ssthresh	= tcp_reno_ssthresh,
+	.cong_avoid	= mptcp_olia_cong_avoid,
+	.set_state	= mptcp_olia_set_state,
+	.min_cwnd	= tcp_reno_min_cwnd,
+	.owner		= THIS_MODULE,
+	.name		= "olia",
+};
+
+static int __init mptcp_olia_register(void)
+{
+	BUILD_BUG_ON(sizeof(struct mptcp_olia) > ICSK_CA_PRIV_SIZE);
+	return tcp_register_congestion_control(&mptcp_olia);
+}
+
+static void __exit mptcp_olia_unregister(void)
+{
+	tcp_unregister_congestion_control(&mptcp_olia);
+}
+
+module_init(mptcp_olia_register);
+module_exit(mptcp_olia_unregister);
+
+MODULE_AUTHOR("Ramin Khalili, Nicolas Gast, Jean-Yves Le Boudec");
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("MPTCP COUPLED CONGESTION CONTROL");
+MODULE_VERSION("0.1");
diff -Naur a/net/mptcp/mptcp_output.c b/net/mptcp/mptcp_output.c
--- a/net/mptcp/mptcp_output.c	1970-01-01 01:00:00.000000000 +0100
+++ b/net/mptcp/mptcp_output.c	2013-10-06 18:26:04.524865795 +0200
@@ -0,0 +1,2334 @@
+/*
+ *	MPTCP implementation - Sending side
+ *
+ *	Initial Design & Implementation:
+ *	Sébastien Barré <[e-mail]>
+ *
+ *	Current Maintainer & Author:
+ *	Christoph Paasch <[e-mail]>
+ *
+ *	Additional authors:
+ *	Jaakko Korkeaniemi <[e-mail]>
+ *	Gregory Detal <[e-mail]>
+ *	Fabien Duchêne <[e-mail]>
+ *	Andreas Seelinger <[e-mail]>
+ *	Lavkesh Lahngir <[e-mail]>
+ *	Andreas Ripke <[e-mail]>
+ *	Vlad Dogaru <[e-mail]>
+ *	Octavian Purdila <[e-mail]>
+ *	John Ronan <[e-mail]>
+ *	Catalin Nicutar <[e-mail]>
+ *	Brandon Heller <[e-mail]>
+ *
+ *
+ *	This program is free software; you can redistribute it and/or
+ *      modify it under the terms of the GNU General Public License
+ *      as published by the Free Software Foundation; either version
+ *      2 of the License, or (at your option) any later version.
+ */
+
+#include <linux/kconfig.h>
+#include <linux/skbuff.h>
+#include <linux/tcp.h>
+
+#include <net/mptcp.h>
+#include <net/mptcp_v4.h>
+#include <net/mptcp_v6.h>
+#include <net/sock.h>
+
+/* If the sub-socket sk available to send the skb? */
+static int mptcp_is_available(struct sock *sk, struct sk_buff *skb,
+			      unsigned int *mss)
+{
+	struct tcp_sock *tp = tcp_sk(sk);
+	unsigned int mss_now;
+
+	/* Set of states for which we are allowed to send data */
+	if (!mptcp_sk_can_send(sk))
+		return 0;
+
+	/* We do not send data on this subflow unless it is
+	 * fully established, i.e. the 4th ack has been received.
+	 */
+	if (tp->mptcp->pre_established)
+		return 0;
+
+	if (tp->pf ||
+	    (tp->mpcb->noneligible & mptcp_pi_to_flag(tp->mptcp->path_index)))
+		return 0;
+
+	if (inet_csk(sk)->icsk_ca_state == TCP_CA_Loss) {
+		/* If SACK is disabled, and we got a loss, TCP does not exist
+		 * the loss-state until something above high_seq has been acked.
+		 * (see tcp_try_undo_recovery)
+		 *
+		 * high_seq is the snd_nxt at the moment of the RTO. As soon
+		 * as we have an RTO, we won't push data on the subflow.
+		 * Thus, snd_una can never go beyond high_seq.
+		 */
+		if (!tcp_is_reno(tp))
+			return 0;
+		else if (tp->snd_una != tp->high_seq)
+			return 0;
+	}
+
+	if (!tp->mptcp->fully_established) {
+		/* Make sure that we send in-order data */
+		if (skb && tp->mptcp->second_packet &&
+		    tp->mptcp->last_end_data_seq != TCP_SKB_CB(skb)->seq)
+			return 0;
+	}
+
+	if (!tcp_cwnd_test(tp, skb))
+		return 0;
+
+	mss_now = tcp_current_mss(sk);
+	/* Don't send on this subflow if we bypass the allowed send-window at
+	 * the per-subflow level. Similar to tcp_snd_wnd_test, but manually
+	 * calculated end_seq (because here at this point end_seq is still at
+	 * the meta-level).
+	 */
+	if (skb && after(tp->write_seq + min(skb->len, mss_now), tcp_wnd_end(tp)))
+		return 0;
+
+	if (mss)
+		*mss = mss_now;
+
+	return 1;
+}
+
+/* Are we not allowed to reinject this skb on tp? */
+static int mptcp_dont_reinject_skb(struct tcp_sock *tp, struct sk_buff *skb)
+{
+	/* If the skb has already been enqueued in this sk, try to find
+	 * another one.
+	 * An exception is a DATA_FIN without data. These ones are not
+	 * reinjected at the subflow-level as they do not consume
+	 * subflow-sequence-number space.
+	 */
+	return skb &&
+		/* We either have a data_fin with data or not a data_fin */
+		((mptcp_is_data_fin(skb) && TCP_SKB_CB(skb)->end_seq - TCP_SKB_CB(skb)->seq  > 1) ||
+		!mptcp_is_data_fin(skb)) &&
+		/* Has the skb already been enqueued into this subsocket? */
+		mptcp_pi_to_flag(tp->mptcp->path_index) & TCP_SKB_CB(skb)->path_mask;
+}
+
+/* This is the scheduler. This function decides on which flow to send
+ * a given MSS. If all subflows are found to be busy, NULL is returned
+ * The flow is selected based on the shortest RTT.
+ * If all paths have full cong windows, we simply return NULL.
+ *
+ * Additionally, this function is aware of the backup-subflows.
+ */
+static struct sock *get_available_subflow(struct sock *meta_sk,
+					  struct sk_buff *skb,
+					  unsigned int *mss_now)
+{
+	struct mptcp_cb *mpcb = tcp_sk(meta_sk)->mpcb;
+	struct sock *sk, *bestsk = NULL, *lowpriosk = NULL, *backupsk = NULL;
+	unsigned int mss = 0, mss_lowprio = 0, mss_backup = 0;
+	u32 min_time_to_peer = 0xffffffff, lowprio_min_time_to_peer = 0xffffffff;
+	int cnt_backups = 0;
+
+	/* if there is only one subflow, bypass the scheduling function */
+	if (mpcb->cnt_subflows == 1) {
+		bestsk = (struct sock *)mpcb->connection_list;
+		if (!mptcp_is_available(bestsk, skb, mss_now))
+			bestsk = NULL;
+		return bestsk;
+	}
+
+	/* Answer data_fin on same subflow!!! */
+	if (meta_sk->sk_shutdown & RCV_SHUTDOWN &&
+	    skb && mptcp_is_data_fin(skb)) {
+		mptcp_for_each_sk(mpcb, sk) {
+			if (tcp_sk(sk)->mptcp->path_index == mpcb->dfin_path_index &&
+			    mptcp_is_available(sk, skb, mss_now))
+				return sk;
+		}
+	}
+
+	/* First, find the best subflow */
+	mptcp_for_each_sk(mpcb, sk) {
+		struct tcp_sock *tp = tcp_sk(sk);
+		int this_mss;
+
+		if (tp->mptcp->rcv_low_prio || tp->mptcp->low_prio)
+			cnt_backups++;
+
+		if ((tp->mptcp->rcv_low_prio || tp->mptcp->low_prio) &&
+		    tp->srtt < lowprio_min_time_to_peer) {
+
+			if (!mptcp_is_available(sk, skb, &this_mss))
+				continue;
+
+			if (mptcp_dont_reinject_skb(tp, skb)) {
+				mss_backup = this_mss;
+				backupsk = sk;
+				continue;
+			}
+
+			lowprio_min_time_to_peer = tp->srtt;
+			lowpriosk = sk;
+			mss_lowprio = this_mss;
+		} else if (!(tp->mptcp->rcv_low_prio || tp->mptcp->low_prio) &&
+			   tp->srtt < min_time_to_peer) {
+			if (!mptcp_is_available(sk, skb, &this_mss))
+				continue;
+
+			if (mptcp_dont_reinject_skb(tp, skb)) {
+				mss_backup = this_mss;
+				backupsk = sk;
+				continue;
+			}
+
+			min_time_to_peer = tp->srtt;
+			bestsk = sk;
+			mss = this_mss;
+		}
+	}
+
+	if (mpcb->cnt_established == cnt_backups && lowpriosk) {
+		mss = mss_lowprio;
+		sk = lowpriosk;
+	} else if (bestsk) {
+		sk = bestsk;
+	} else if (backupsk){
+		/* It has been sent on all subflows once - let's give it a
+		 * chance again by restarting its pathmask.
+		 */
+		if (skb)
+			TCP_SKB_CB(skb)->path_mask = 0;
+		mss = mss_backup;
+		sk = backupsk;
+	}
+
+	if (mss_now)
+		*mss_now = mss;
+
+	return sk;
+}
+
+static struct mp_dss *mptcp_skb_find_dss(const struct sk_buff *skb)
+{
+	if (!mptcp_is_data_seq(skb))
+		return NULL;
+
+	return (struct mp_dss *)(skb->data - (MPTCP_SUB_LEN_DSS_ALIGN +
+					      MPTCP_SUB_LEN_ACK_ALIGN +
+					      MPTCP_SUB_LEN_SEQ_ALIGN));
+}
+
+/* get the data-seq and end-data-seq and store them again in the
+ * tcp_skb_cb
+ */
+static int mptcp_reconstruct_mapping(struct sk_buff *skb, struct sk_buff *orig_skb)
+{
+	struct mp_dss *mpdss = mptcp_skb_find_dss(orig_skb);
+	u32 *p32;
+	u16 *p16;
+
+	if (!mpdss || !mpdss->M)
+		return 1;
+
+	/* Move the pointer to the data-seq */
+	p32 = (u32 *)mpdss;
+	p32++;
+	if (mpdss->A) {
+		p32++;
+		if (mpdss->a)
+			p32++;
+	}
+
+	TCP_SKB_CB(skb)->seq = ntohl(*p32);
+
+	/* Get the data_len to calculate the end_data_seq */
+	p32++;
+	p32++;
+	p16 = (u16 *)p32;
+	TCP_SKB_CB(skb)->end_seq = ntohs(*p16) + TCP_SKB_CB(skb)->seq;
+
+	return 0;
+}
+
+/* Similar to __pskb_copy and sk_stream_alloc_skb. */
+static struct sk_buff *mptcp_pskb_copy(struct sk_buff *skb)
+{
+	struct sk_buff *n;
+	/* The TCP header must be at least 32-bit aligned.  */
+	int size = ALIGN(skb_headlen(skb), 4);
+
+	n = alloc_skb_fclone(size + MAX_TCP_HEADER, GFP_ATOMIC);
+	if (!n)
+		return NULL;
+
+	/* Set the data pointer */
+	skb_reserve(n, MAX_TCP_HEADER);
+	/* Set the tail pointer and length */
+	skb_put(n, skb_headlen(skb));
+	/* Copy the bytes */
+	skb_copy_from_linear_data(skb, n->data, n->len);
+
+	n->truesize += skb->data_len;
+	n->data_len  = skb->data_len;
+	n->len	     = skb->len;
+
+	if (skb_shinfo(skb)->nr_frags) {
+		int i;
+
+		if (skb_shinfo(skb)->tx_flags & SKBTX_DEV_ZEROCOPY) {
+			if (skb_copy_ubufs(skb, GFP_ATOMIC)) {
+				kfree_skb(n);
+				n = NULL;
+				goto out;
+			}
+		}
+		for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
+			skb_shinfo(n)->frags[i] = skb_shinfo(skb)->frags[i];
+			skb_frag_ref(skb, i);
+		}
+		skb_shinfo(n)->nr_frags = i;
+	}
+
+	if (skb_has_frag_list(skb)) {
+		skb_shinfo(n)->frag_list = skb_shinfo(skb)->frag_list;
+		skb_clone_fraglist(n);
+	}
+
+	copy_skb_header(n, skb);
+out:
+	return n;
+}
+
+/* Reinject data from one TCP subflow to the meta_sk. If sk == NULL, we are
+ * coming from the meta-retransmit-timer
+ */
+static void __mptcp_reinject_data(struct sk_buff *orig_skb, struct sock *meta_sk,
+				  struct sock *sk, int clone_it)
+{
+	struct sk_buff *skb, *skb1;
+	struct tcp_sock *meta_tp = tcp_sk(meta_sk);
+	struct mptcp_cb *mpcb = meta_tp->mpcb;
+	u32 seq, end_seq;
+
+	if (clone_it) {
+		/* pskb_copy is necessary here, because the TCP/IP-headers
+		 * will be changed when it's going to be reinjected on another
+		 * subflow.
+		 */
+		skb = mptcp_pskb_copy(orig_skb);
+	} else {
+		__skb_unlink(orig_skb, &sk->sk_write_queue);
+		sock_set_flag(sk, SOCK_QUEUE_SHRUNK);
+		sk->sk_wmem_queued -= orig_skb->truesize;
+		sk_mem_uncharge(sk, orig_skb->truesize);
+		skb = orig_skb;
+	}
+	if (unlikely(!skb))
+		return;
+
+	if (sk && mptcp_reconstruct_mapping(skb, orig_skb)) {
+		__kfree_skb(skb);
+		return;
+	}
+
+	skb->sk = meta_sk;
+
+	/* If it reached already the destination, we don't have to reinject it */
+	if (!after(TCP_SKB_CB(skb)->end_seq, meta_tp->snd_una)) {
+		__kfree_skb(skb);
+		return;
+	}
+
+	/* Only reinject segments that are fully covered by the mapping */
+	if (skb->len + (mptcp_is_data_fin(skb) ? 1 : 0) !=
+	    TCP_SKB_CB(skb)->end_seq - TCP_SKB_CB(skb)->seq) {
+		u32 seq = TCP_SKB_CB(skb)->seq;
+		u32 end_seq = TCP_SKB_CB(skb)->end_seq;
+
+		__kfree_skb(skb);
+
+		/* Ok, now we have to look for the full mapping in the meta
+		 * send-queue :S
+		 */
+		tcp_for_write_queue(skb, meta_sk) {
+			/* Not yet at the mapping? */
+			if (before(TCP_SKB_CB(skb)->seq, seq))
+				continue;
+			/* We have passed by the mapping */
+			if (after(TCP_SKB_CB(skb)->end_seq, end_seq))
+				return;
+
+			__mptcp_reinject_data(skb, meta_sk, NULL, 1);
+		}
+		return;
+	}
+
+	/* If it's empty, just add */
+	if (skb_queue_empty(&mpcb->reinject_queue)) {
+		skb_queue_head(&mpcb->reinject_queue, skb);
+		return;
+	}
+
+	/* Find place to insert skb - or even we can 'drop' it, as the
+	 * data is already covered by other skb's in the reinject-queue.
+	 *
+	 * This is inspired by code from tcp_data_queue.
+	 */
+
+	skb1 = skb_peek_tail(&mpcb->reinject_queue);
+	seq = TCP_SKB_CB(skb)->seq;
+	while (1) {
+		if (!after(TCP_SKB_CB(skb1)->seq, seq))
+			break;
+		if (skb_queue_is_first(&mpcb->reinject_queue, skb1)) {
+			skb1 = NULL;
+			break;
+		}
+		skb1 = skb_queue_prev(&mpcb->reinject_queue, skb1);
+	}
+
+	/* Do skb overlap to previous one? */
+	end_seq = TCP_SKB_CB(skb)->end_seq;
+	if (skb1 && before(seq, TCP_SKB_CB(skb1)->end_seq)) {
+		if (!after(end_seq, TCP_SKB_CB(skb1)->end_seq)) {
+			/* All the bits are present. Don't reinject */
+			__kfree_skb(skb);
+			return;
+		}
+		if (seq == TCP_SKB_CB(skb1)->seq) {
+			if (skb_queue_is_first(&mpcb->reinject_queue, skb1))
+				skb1 = NULL;
+			else
+				skb1 = skb_queue_prev(&mpcb->reinject_queue, skb1);
+		}
+	}
+	if (!skb1)
+		__skb_queue_head(&mpcb->reinject_queue, skb);
+	else
+		__skb_queue_after(&mpcb->reinject_queue, skb1, skb);
+
+	/* And clean segments covered by new one as whole. */
+	while (!skb_queue_is_last(&mpcb->reinject_queue, skb)) {
+		skb1 = skb_queue_next(&mpcb->reinject_queue, skb);
+
+		if (!after(end_seq, TCP_SKB_CB(skb1)->seq))
+			break;
+
+		__skb_unlink(skb1, &mpcb->reinject_queue);
+		__kfree_skb(skb1);
+	}
+	return;
+}
+
+/* Inserts data into the reinject queue */
+void mptcp_reinject_data(struct sock *sk, int clone_it)
+{
+	struct sk_buff *skb_it, *tmp;
+	struct tcp_sock *tp = tcp_sk(sk);
+	struct sock *meta_sk = tp->meta_sk;
+
+	/* It has already been closed - there is really no point in reinjecting */
+	if (meta_sk->sk_state == TCP_CLOSE)
+		return;
+
+	skb_queue_walk_safe(&sk->sk_write_queue, skb_it, tmp) {
+		struct tcp_skb_cb *tcb = TCP_SKB_CB(skb_it);
+		/* Subflow syn's and fin's are not reinjected.
+		 *
+		 * As well as empty subflow-fins with a data-fin.
+		 * They are reinjected below (without the subflow-fin-flag)
+		 */
+		if (tcb->tcp_flags & TCPHDR_SYN ||
+		    (tcb->tcp_flags & TCPHDR_FIN && !mptcp_is_data_fin(skb_it)) ||
+		    (tcb->tcp_flags & TCPHDR_FIN && mptcp_is_data_fin(skb_it) && !skb_it->len))
+			continue;
+
+		__mptcp_reinject_data(skb_it, meta_sk, sk, clone_it);
+	}
+
+	skb_it = tcp_write_queue_tail(meta_sk);
+	/* If sk has sent the empty data-fin, we have to reinject it too. */
+	if (skb_it && mptcp_is_data_fin(skb_it) && skb_it->len == 0 &&
+	    TCP_SKB_CB(skb_it)->path_mask & mptcp_pi_to_flag(tp->mptcp->path_index)) {
+		__mptcp_reinject_data(skb_it, meta_sk, NULL, 1);
+	}
+
+	mptcp_push_pending_frames(meta_sk);
+
+	tp->pf = 1;
+}
+
+
+static void mptcp_combine_dfin(struct sk_buff *skb, struct sock *meta_sk,
+			       struct sock *subsk)
+{
+	struct tcp_sock *meta_tp = tcp_sk(meta_sk);
+	struct mptcp_cb *mpcb = meta_tp->mpcb;
+	struct sock *sk_it;
+	int all_empty = 1, all_acked;
+
+	/* In infinite mapping we always try to combine */
+	if (mpcb->infinite_mapping_snd && tcp_close_state(subsk)) {
+		TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_FIN;
+		return;
+	}
+
+	/* Don't combine, if they didn't combine - otherwise we end up in
+	 * TIME_WAIT, even if our app is smart enough to avoid it
+	 */
+	if (meta_sk->sk_shutdown & RCV_SHUTDOWN) {
+		if (!mpcb->dfin_combined)
+			return;
+	}
+
+	/* If no other subflow has data to send, we can combine */
+	mptcp_for_each_sk(mpcb, sk_it) {
+		if (!mptcp_sk_can_send(sk_it))
+			continue;
+
+		if (!tcp_write_queue_empty(sk_it))
+			all_empty = 0;
+	}
+
+	/* If all data has been DATA_ACKed, we can combine.
+	 * -1, because the data_fin consumed one byte
+	 */
+	all_acked = (meta_tp->snd_una == (meta_tp->write_seq - 1));
+
+	if ((all_empty || all_acked) && tcp_close_state(subsk))
+		TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_FIN;
+}
+
+static struct sk_buff *mptcp_skb_entail(struct sock *sk, struct sk_buff *skb,
+					int reinject)
+{
+	__be32 *ptr;
+	__u16 data_len;
+	struct mp_dss *mdss;
+	struct tcp_sock *tp = tcp_sk(sk);
+	struct sock *meta_sk = mptcp_meta_sk(sk);
+	struct mptcp_cb *mpcb = tp->mpcb;
+	struct tcp_skb_cb *tcb;
+	struct sk_buff *subskb = NULL;
+
+	if (!reinject)
+		TCP_SKB_CB(skb)->mptcp_flags |= (mpcb->snd_hiseq_index ?
+						  MPTCPHDR_SEQ64_INDEX : 0);
+
+	subskb = mptcp_pskb_copy(skb);
+	if (!subskb)
+		return NULL;
+
+	TCP_SKB_CB(skb)->path_mask |= mptcp_pi_to_flag(tp->mptcp->path_index);
+
+	if (!(sk->sk_route_caps & NETIF_F_ALL_CSUM) &&
+	    skb->ip_summed == CHECKSUM_PARTIAL) {
+		subskb->csum = skb->csum = skb_checksum(skb, 0, skb->len, 0);
+		subskb->ip_summed = skb->ip_summed = CHECKSUM_NONE;
+	}
+
+	/* The subskb is going in the subflow send-queue. Its path-mask
+	 * is not needed anymore and MUST be set to 0, as the path-mask
+	 * is a union with inet_skb_param.
+	 */
+	tcb = TCP_SKB_CB(subskb);
+	tcb->path_mask = 0;
+
+	if (mptcp_is_data_fin(subskb))
+		mptcp_combine_dfin(subskb, meta_sk, sk);
+
+	if (tp->mpcb->infinite_mapping_snd)
+		goto no_data_seq;
+
+	if (tp->mpcb->send_infinite_mapping &&
+	    !before(tcb->seq, mptcp_meta_tp(tp)->snd_nxt)) {
+		tp->mptcp->fully_established = 1;
+		tp->mpcb->infinite_mapping_snd = 1;
+		tp->mptcp->infinite_cutoff_seq = tp->write_seq;
+		tcb->mptcp_flags |= MPTCPHDR_INF;
+		data_len = 0;
+	} else {
+		data_len = tcb->end_seq - tcb->seq;
+	}
+
+	/**** Write MPTCP DSS-option to the packet. ****/
+	ptr = (__be32 *)(subskb->data - (MPTCP_SUB_LEN_DSS_ALIGN +
+				      MPTCP_SUB_LEN_ACK_ALIGN +
+				      MPTCP_SUB_LEN_SEQ_ALIGN));
+
+	/* Then we start writing it from the start */
+	mdss = (struct mp_dss *)ptr;
+
+	mdss->kind = TCPOPT_MPTCP;
+	mdss->sub = MPTCP_SUB_DSS;
+	mdss->rsv1 = 0;
+	mdss->rsv2 = 0;
+	mdss->F = (mptcp_is_data_fin(subskb) ? 1 : 0);
+	mdss->m = 0;
+	mdss->M = 1;
+	mdss->a = 0;
+	mdss->A = 1;
+	mdss->len = mptcp_sub_len_dss(mdss, tp->mpcb->dss_csum);
+
+	ptr++;
+	ptr++; /* data_ack will be set in mptcp_options_write */
+	*ptr++ = htonl(tcb->seq); /* data_seq */
+
+	/* If it's a non-data DATA_FIN, we set subseq to 0 (draft v7) */
+	if (mptcp_is_data_fin(subskb) && subskb->len == 0)
+		*ptr++ = 0; /* subseq */
+	else
+		*ptr++ = htonl(tp->write_seq - tp->mptcp->snt_isn); /* subseq */
+
+	if (tp->mpcb->dss_csum && data_len) {
+		__be16 *p16 = (__be16 *)ptr;
+		__be32 hdseq = mptcp_get_highorder_sndbits(subskb, tp->mpcb);
+		__wsum csum;
+		*ptr = htonl(((data_len) << 16) |
+				(TCPOPT_EOL << 8) |
+				(TCPOPT_EOL));
+
+		csum = csum_partial(ptr - 2, 12, subskb->csum);
+		p16++;
+		*p16++ = csum_fold(csum_partial(&hdseq, sizeof(hdseq), csum));
+	} else {
+		*ptr++ = htonl(((data_len) << 16) |
+				(TCPOPT_NOP << 8) |
+				(TCPOPT_NOP));
+	}
+
+no_data_seq:
+	tcb->seq = tp->write_seq;
+	tcb->sacked = 0; /* reset the sacked field: from the point of view
+			  * of this subflow, we are sending a brand new
+			  * segment */
+	/* Take into account seg len */
+	tp->write_seq += subskb->len + ((tcb->tcp_flags & TCPHDR_FIN) ? 1 : 0);
+	tcb->end_seq = tp->write_seq;
+
+	/* If it's a non-payload DATA_FIN (also no subflow-fin), the
+	 * segment is not part of the subflow but on a meta-only-level
+	 */
+	if (!mptcp_is_data_fin(subskb) || tcb->end_seq != tcb->seq) {
+		tcp_add_write_queue_tail(sk, subskb);
+		sk->sk_wmem_queued += subskb->truesize;
+		sk_mem_charge(sk, subskb->truesize);
+	}
+
+	return subskb;
+}
+
+static void mptcp_sub_event_new_data_sent(struct sock *sk,
+					  struct sk_buff *subskb,
+					  struct sk_buff *skb)
+{
+	/* If it's a non-payload DATA_FIN (also no subflow-fin), the
+	 * segment is not part of the subflow but on a meta-only-level
+	 *
+	 * We free it, because it has been queued nowhere.
+	 */
+	if (!mptcp_is_data_fin(subskb) ||
+	    (TCP_SKB_CB(subskb)->end_seq != TCP_SKB_CB(subskb)->seq)) {
+		tcp_event_new_data_sent(sk, subskb);
+		tcp_sk(sk)->mptcp->second_packet = 1;
+		tcp_sk(sk)->mptcp->last_end_data_seq = TCP_SKB_CB(skb)->end_seq;
+	} else {
+		kfree_skb(subskb);
+	}
+}
+
+/* Handle the packets and sockets after a tcp_transmit_skb failed */
+static void mptcp_transmit_skb_failed(struct sock *sk, struct sk_buff *skb,
+				      struct sk_buff *subskb, int reinject)
+{
+	struct tcp_sock *tp = tcp_sk(sk);
+	struct mptcp_cb *mpcb = tp->mpcb;
+
+	/* No work to do if we are in infinite mapping mode
+	 * There is only one subflow left and we cannot send this segment on
+	 * another subflow.
+	 */
+	if (mpcb->infinite_mapping_snd)
+		return;
+
+	TCP_SKB_CB(skb)->path_mask &= ~mptcp_pi_to_flag(tp->mptcp->path_index);
+
+	if (TCP_SKB_CB(subskb)->tcp_flags & TCPHDR_FIN) {
+		/* If it is a subflow-fin we must leave it on the
+		 * subflow-send-queue, so that the probe-timer
+		 * can retransmit it.
+		 */
+		if (!tp->packets_out && !inet_csk(sk)->icsk_pending)
+			inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0,
+						  inet_csk(sk)->icsk_rto, TCP_RTO_MAX);
+	} else if (mptcp_is_data_fin(subskb) &&
+		   TCP_SKB_CB(subskb)->end_seq == TCP_SKB_CB(subskb)->seq) {
+		/* An empty data-fin has not been enqueued on the subflow
+		 * and thus we free it.
+		 */
+
+		kfree_skb(subskb);
+	} else {
+		/* In all other cases we remove it from the sub-queue.
+		 * Other subflows may send it, or the probe-timer will
+		 * handle it.
+		 */
+		tcp_advance_send_head(sk, subskb);
+
+		/* tcp_add_write_queue_tail initialized highest_sack. We have
+		 * to reset it, if necessary.
+		 */
+		if (tp->highest_sack == subskb)
+			tp->highest_sack = NULL;
+
+		tcp_unlink_write_queue(subskb, sk);
+		tp->write_seq -= subskb->len;
+		sk_wmem_free_skb(sk, subskb);
+	}
+}
+
+/* Function to create two new TCP segments.  Shrinks the given segment
+ * to the specified size and appends a new segment with the rest of the
+ * packet to the list.  This won't be called frequently, I hope.
+ * Remember, these are still headerless SKBs at this point.
+ */
+int mptcp_fragment(struct sock *sk, struct sk_buff *skb, u32 len,
+		   unsigned int mss_now, int reinject)
+{
+	struct tcp_sock *tp = tcp_sk(sk);
+	struct sk_buff *buff;
+	int nsize, old_factor;
+	int nlen;
+	u8 flags;
+	int dsslen = MPTCP_SUB_LEN_DSS_ALIGN + MPTCP_SUB_LEN_ACK_ALIGN +
+		     MPTCP_SUB_LEN_SEQ_ALIGN;
+	char dss[dsslen];
+
+	if (WARN_ON(len > skb->len))
+		return -EINVAL;
+
+	/* DSS-option must be recovered afterwards. */
+	if (!is_meta_sk(sk))
+		memcpy(dss, skb->data - dsslen, dsslen);
+
+	nsize = skb_headlen(skb) - len;
+	if (nsize < 0)
+		nsize = 0;
+
+	if (skb_cloned(skb) &&
+	    skb_is_nonlinear(skb)) {
+		if (pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
+			return -ENOMEM;
+		/* Recover dss-option */
+		if (!is_meta_sk(sk))
+			memcpy(skb->data - dsslen, dss, dsslen);
+	}
+
+	/* Get a new skb... force flag on. */
+	buff = sk_stream_alloc_skb(sk, nsize, GFP_ATOMIC);
+	if (buff == NULL)
+		return -ENOMEM; /* We'll just try again later. */
+
+	/* See below - if reinject == 1, the buff will be added to the reinject-
+	 * queue, which is currently not part of the memory-accounting.
+	 */
+	if (reinject != 1) {
+		sk->sk_wmem_queued += buff->truesize;
+		sk_mem_charge(sk, buff->truesize);
+	}
+	nlen = skb->len - len - nsize;
+	buff->truesize += nlen;
+	skb->truesize -= nlen;
+
+	/* Correct the sequence numbers. */
+	TCP_SKB_CB(buff)->seq = TCP_SKB_CB(skb)->seq + len;
+	TCP_SKB_CB(buff)->end_seq = TCP_SKB_CB(skb)->end_seq;
+	TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(buff)->seq;
+
+	/* PSH and FIN should only be set in the second packet. */
+	flags = TCP_SKB_CB(skb)->tcp_flags;
+	TCP_SKB_CB(skb)->tcp_flags = flags & ~(TCPHDR_FIN | TCPHDR_PSH);
+	TCP_SKB_CB(buff)->tcp_flags = flags;
+	TCP_SKB_CB(buff)->sacked = TCP_SKB_CB(skb)->sacked;
+
+	flags = TCP_SKB_CB(skb)->mptcp_flags;
+	TCP_SKB_CB(skb)->mptcp_flags = flags & ~(MPTCPHDR_FIN);
+	TCP_SKB_CB(buff)->mptcp_flags = flags;
+
+	if (!skb_shinfo(skb)->nr_frags && skb->ip_summed != CHECKSUM_PARTIAL) {
+		/* Copy and checksum data tail into the new buffer. */
+		buff->csum = csum_partial_copy_nocheck(skb->data + len,
+						       skb_put(buff, nsize),
+						       nsize, 0);
+
+		skb_trim(skb, len);
+
+		skb->csum = csum_block_sub(skb->csum, buff->csum, len);
+	} else {
+		skb->ip_summed = CHECKSUM_PARTIAL;
+		skb_split(skb, buff, len);
+	}
+
+	/* We lost the dss-option when creating buff - put it back! */
+	if (!is_meta_sk(sk))
+		memcpy(buff->data - dsslen, dss, dsslen);
+
+	buff->ip_summed = skb->ip_summed;
+
+	/* Looks stupid, but our code really uses when of
+	 * skbs, which it never sent before. --ANK
+	 */
+	TCP_SKB_CB(buff)->when = TCP_SKB_CB(skb)->when;
+	buff->tstamp = skb->tstamp;
+
+	old_factor = tcp_skb_pcount(skb);
+
+	/* Fix up tso_factor for both original and new SKB.  */
+	tcp_set_skb_tso_segs(sk, skb, mss_now);
+	tcp_set_skb_tso_segs(sk, buff, mss_now);
+
+	/* If this packet has been sent out already, we must
+	 * adjust the various packet counters.
+	 */
+	if (!before(tp->snd_nxt, TCP_SKB_CB(buff)->end_seq) && reinject != 1) {
+		int diff = old_factor - tcp_skb_pcount(skb) -
+			tcp_skb_pcount(buff);
+
+		if (diff)
+			tcp_adjust_pcount(sk, skb, diff);
+	}
+
+	/* Link BUFF into the send queue. */
+	skb_header_release(buff);
+	if (reinject == 1)
+		__skb_queue_after(&tcp_sk(sk)->mpcb->reinject_queue, skb, buff);
+	else
+		tcp_insert_write_queue_after(skb, buff, sk);
+
+	return 0;
+}
+
+int mptso_fragment(struct sock *sk, struct sk_buff *skb, unsigned int len,
+		   unsigned int mss_now, gfp_t gfp, int reinject)
+{
+	struct sk_buff *buff;
+	int nlen = skb->len - len, old_factor;
+	u8 flags;
+	int dsslen = MPTCP_SUB_LEN_DSS_ALIGN + MPTCP_SUB_LEN_ACK_ALIGN +
+		     MPTCP_SUB_LEN_SEQ_ALIGN;
+
+	/* All of a TSO frame must be composed of paged data.  */
+	if (skb->len != skb->data_len)
+		return mptcp_fragment(sk, skb, len, mss_now, reinject);
+
+	buff = sk_stream_alloc_skb(sk, 0, gfp);
+	if (unlikely(buff == NULL))
+		return -ENOMEM;
+
+	/* See below - if reinject == 1, the buff will be added to the reinject-
+	 * queue, which is currently not part of the memory-accounting.
+	 */
+	if (reinject != 1) {
+		sk->sk_wmem_queued += buff->truesize;
+		sk_mem_charge(sk, buff->truesize);
+	}
+	buff->truesize += nlen;
+	skb->truesize -= nlen;
+
+	/* Correct the sequence numbers. */
+	TCP_SKB_CB(buff)->seq = TCP_SKB_CB(skb)->seq + len;
+	TCP_SKB_CB(buff)->end_seq = TCP_SKB_CB(skb)->end_seq;
+	TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(buff)->seq;
+
+	/* PSH and FIN should only be set in the second packet. */
+	flags = TCP_SKB_CB(skb)->tcp_flags;
+	TCP_SKB_CB(skb)->tcp_flags = flags & ~(TCPHDR_FIN | TCPHDR_PSH);
+	TCP_SKB_CB(buff)->tcp_flags = flags;
+
+	flags = TCP_SKB_CB(skb)->mptcp_flags;
+	TCP_SKB_CB(skb)->mptcp_flags = flags & ~(MPTCPHDR_FIN);
+	TCP_SKB_CB(buff)->mptcp_flags = flags;
+
+	/* This packet was never sent out yet, so no SACK bits. */
+	TCP_SKB_CB(buff)->sacked = 0;
+
+	buff->ip_summed = CHECKSUM_PARTIAL;
+	skb->ip_summed = CHECKSUM_PARTIAL;
+	skb_split(skb, buff, len);
+
+	/* We lost the dss-option when creating buff - put it back! */
+	if (!is_meta_sk(sk))
+		memcpy(buff->data - dsslen, skb->data - dsslen, dsslen);
+
+	old_factor = tcp_skb_pcount(skb);
+
+	/* Fix up tso_factor for both original and new SKB.  */
+	tcp_set_skb_tso_segs(sk, skb, mss_now);
+	tcp_set_skb_tso_segs(sk, buff, mss_now);
+
+	/* If this packet has been sent out already, we must
+	 * adjust the various packet counters.
+	 */
+	if (!before(tcp_sk(sk)->snd_nxt, TCP_SKB_CB(buff)->end_seq) && reinject != 1) {
+		int diff = old_factor - tcp_skb_pcount(skb) -
+			tcp_skb_pcount(buff);
+
+		if (diff)
+			tcp_adjust_pcount(sk, skb, diff);
+	}
+
+	/* Link BUFF into the send queue. */
+	skb_header_release(buff);
+	if (reinject == 1)
+		__skb_queue_after(&tcp_sk(sk)->mpcb->reinject_queue, skb, buff);
+	else
+		tcp_insert_write_queue_after(skb, buff, sk);
+
+	return 0;
+}
+
+/* Inspired by tcp_write_wakeup */
+int mptcp_write_wakeup(struct sock *meta_sk)
+{
+	struct tcp_sock *meta_tp = tcp_sk(meta_sk);
+	struct sk_buff *skb, *subskb;
+
+	skb = tcp_send_head(meta_sk);
+	if (skb &&
+	    before(TCP_SKB_CB(skb)->seq, tcp_wnd_end(meta_tp))) {
+		int err;
+		unsigned int mss;
+		unsigned int seg_size = tcp_wnd_end(meta_tp) - TCP_SKB_CB(skb)->seq;
+		struct sock *subsk = get_available_subflow(meta_sk, skb, &mss);
+		if (!subsk)
+			return -1;
+
+		if (before(meta_tp->pushed_seq, TCP_SKB_CB(skb)->end_seq))
+			meta_tp->pushed_seq = TCP_SKB_CB(skb)->end_seq;
+
+		/* We are probing the opening of a window
+		 * but the window size is != 0
+		 * must have been a result SWS avoidance ( sender )
+		 */
+		if (seg_size < TCP_SKB_CB(skb)->end_seq - TCP_SKB_CB(skb)->seq ||
+		    skb->len > mss) {
+			seg_size = min(seg_size, mss);
+			TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_PSH;
+			if (mptcp_fragment(meta_sk, skb, seg_size, mss, 0))
+				return -1;
+		} else if (!tcp_skb_pcount(skb)) {
+			tcp_set_skb_tso_segs(meta_sk, skb, mss);
+		}
+
+		subskb = mptcp_skb_entail(subsk, skb, 0);
+		if (!subskb)
+			return -1;
+
+		TCP_SKB_CB(subskb)->tcp_flags |= TCPHDR_PSH;
+		TCP_SKB_CB(skb)->when = tcp_time_stamp;
+		TCP_SKB_CB(subskb)->when = tcp_time_stamp;
+		err = tcp_transmit_skb(subsk, subskb, 1, GFP_ATOMIC);
+		if (unlikely(err)) {
+			mptcp_transmit_skb_failed(subsk, skb, subskb, 0);
+			return err;
+		}
+
+		mptcp_check_sndseq_wrap(meta_tp, TCP_SKB_CB(skb)->end_seq -
+						 TCP_SKB_CB(skb)->seq);
+		tcp_event_new_data_sent(meta_sk, skb);
+		mptcp_sub_event_new_data_sent(subsk, subskb, skb);
+
+		return 0;
+	} else {
+		struct sock *sk_it;
+		int ans = 0;
+
+		if (between(meta_tp->snd_up, meta_tp->snd_una + 1,
+			    meta_tp->snd_una + 0xFFFF)) {
+			mptcp_for_each_sk(meta_tp->mpcb, sk_it) {
+				if (mptcp_sk_can_send_ack(sk_it))
+					tcp_xmit_probe_skb(sk_it, 1);
+			}
+		}
+
+		/* At least one of the tcp_xmit_probe_skb's has to succeed */
+		mptcp_for_each_sk(meta_tp->mpcb, sk_it) {
+			int ret;
+
+			if (!mptcp_sk_can_send_ack(sk_it))
+				continue;
+
+			ret = tcp_xmit_probe_skb(sk_it, 0);
+			if (unlikely(ret > 0))
+				ans = ret;
+		}
+		return ans;
+	}
+}
+
+static void mptcp_find_and_set_pathmask(struct sock *meta_sk, struct sk_buff *skb)
+{
+	struct sk_buff *skb_it;
+
+	skb_it = tcp_write_queue_head(meta_sk);
+
+	tcp_for_write_queue_from(skb_it, meta_sk) {
+		if (skb_it == tcp_send_head(meta_sk))
+			break;
+
+		if (TCP_SKB_CB(skb_it)->seq == TCP_SKB_CB(skb)->seq) {
+			TCP_SKB_CB(skb)->path_mask = TCP_SKB_CB(skb_it)->path_mask;
+			break;
+		}
+	}
+}
+
+static struct sk_buff *mptcp_rcv_buf_optimization(struct sock *sk, int penal)
+{
+	struct sock *meta_sk;
+	struct tcp_sock *tp = tcp_sk(sk), *tp_it;
+	struct sk_buff *skb_head;
+
+	if (tp->mpcb->cnt_subflows == 1)
+		return NULL;
+
+	meta_sk = mptcp_meta_sk(sk);
+	skb_head = tcp_write_queue_head(meta_sk);
+
+	if (!skb_head || skb_head == tcp_send_head(meta_sk))
+		return NULL;
+
+	/* If penalization is optional (coming from mptcp_next_segment() and
+	 * We are not send-buffer-limited we do not penalize. The retransmission
+	 * is just an optimization to fix the idle-time due to the delay before
+	 * we wake up the application.
+	 */
+	if (!penal && sk_stream_memory_free(meta_sk))
+		goto retrans;
+
+	/* Half the cwnd of the slow flow */
+	mptcp_for_each_tp(tp->mpcb, tp_it) {
+		if (tp_it != tp &&
+		    TCP_SKB_CB(skb_head)->path_mask & mptcp_pi_to_flag(tp_it->mptcp->path_index)) {
+			/* Only update every subflow rtt */
+			if (tcp_time_stamp - tp_it->mptcp->last_rbuf_opti < tp_it->srtt >> 3)
+				break;
+
+			if (tp->srtt < tp_it->srtt && inet_csk((struct sock *)tp_it)->icsk_ca_state == TCP_CA_Open) {
+				tp_it->snd_cwnd = max(tp_it->snd_cwnd >> 1U, 1U);
+				if (tp_it->snd_ssthresh != TCP_INFINITE_SSTHRESH)
+					tp_it->snd_ssthresh = max(tp_it->snd_ssthresh >> 1U, 2U);
+
+				tp_it->mptcp->last_rbuf_opti = tcp_time_stamp;
+			}
+			break;
+		}
+	}
+
+retrans:
+
+	/* Segment not yet injected into this path? Take it!!! */
+	if (!(TCP_SKB_CB(skb_head)->path_mask & mptcp_pi_to_flag(tp->mptcp->path_index))) {
+		int do_retrans = 0;
+		mptcp_for_each_tp(tp->mpcb, tp_it) {
+			if (tp_it != tp &&
+			    TCP_SKB_CB(skb_head)->path_mask & mptcp_pi_to_flag(tp_it->mptcp->path_index)) {
+				if (tp_it->snd_cwnd <= 4) {
+					do_retrans = 1;
+					break;
+				}
+
+				if (4 * tp->srtt >= tp_it->srtt) {
+					do_retrans = 0;
+					break;
+				} else {
+					do_retrans = 1;
+				}
+			}
+		}
+
+		if (do_retrans)
+			return skb_head;
+	}
+	return NULL;
+}
+
+int mptcp_write_xmit(struct sock *meta_sk, unsigned int mss_now, int nonagle,
+		     int push_one, gfp_t gfp)
+{
+	struct tcp_sock *meta_tp = tcp_sk(meta_sk), *subtp;
+	struct sock *subsk;
+	struct mptcp_cb *mpcb = meta_tp->mpcb;
+	struct sk_buff *skb;
+	unsigned int tso_segs, sent_pkts;
+	int cwnd_quota;
+	int result;
+	int reinject = 0;
+
+	sent_pkts = 0;
+
+	/* Currently mtu-probing is not done in MPTCP */
+	if (!push_one && 0) {
+		/* Do MTU probing. */
+		result = tcp_mtu_probe(meta_sk);
+		if (!result)
+			return 0;
+		else if (result > 0)
+			sent_pkts = 1;
+	}
+
+	while ((skb = mptcp_next_segment(meta_sk, &reinject))) {
+		unsigned int limit;
+		struct sk_buff *subskb = NULL;
+		u32 noneligible = mpcb->noneligible;
+
+		if (reinject == 1) {
+			if (!after(TCP_SKB_CB(skb)->end_seq, meta_tp->snd_una)) {
+				/* Segment already reached the peer, take the next one */
+				__skb_unlink(skb, &mpcb->reinject_queue);
+				__kfree_skb(skb);
+				continue;
+			}
+
+			/* Reinjection and it is coming from a subflow? We need
+			 * to find out the path-mask from the meta-write-queue
+			 * to properly select a subflow.
+			 */
+			if (!TCP_SKB_CB(skb)->path_mask)
+				mptcp_find_and_set_pathmask(meta_sk, skb);
+		}
+
+subflow:
+		subsk = get_available_subflow(meta_sk, skb, &mss_now);
+		if (!subsk)
+			break;
+		subtp = tcp_sk(subsk);
+
+		/* Since all subsocks are locked before calling the scheduler,
+		 * the tcp_send_head should not change.
+		 */
+		BUG_ON(!reinject && tcp_send_head(meta_sk) != skb);
+retry:
+		/* If the segment was cloned (e.g. a meta retransmission),
+		 * the header must be expanded/copied so that there is no
+		 * corruption of TSO information.
+		 */
+		if (skb_cloned(skb) && skb_is_nonlinear(skb) &&
+		    unlikely(pskb_expand_head(skb, 0, 0, GFP_ATOMIC)))
+			break;
+
+		tso_segs = tcp_init_tso_segs(meta_sk, skb, mss_now);
+		BUG_ON(!tso_segs);
+
+		cwnd_quota = tcp_cwnd_test(subtp, skb);
+		if (!cwnd_quota) {
+			/* May happen, if at the first selection we circumvented
+			 * the test due to a DATA_FIN (and got rejected at
+			 * tcp_snd_wnd_test), but the reinjected segment is not
+			 * a DATA_FIN.
+			 */
+			BUG_ON(reinject != -1);
+			break;
+		}
+
+		if (!reinject && unlikely(!tcp_snd_wnd_test(meta_tp, skb, mss_now))) {
+			skb = mptcp_rcv_buf_optimization(subsk, 1);
+			if (skb) {
+				reinject = -1;
+				goto retry;
+			}
+			break;
+		}
+
+		if (tso_segs == 1) {
+			if (unlikely(!tcp_nagle_test(meta_tp, skb, mss_now,
+						     (tcp_skb_is_last(meta_sk, skb) ?
+						      nonagle : TCP_NAGLE_PUSH))))
+				break;
+		} else {
+			/* Do not try to defer the transmission of a reinjected
+			 * segment. Send it directly.
+			 * If it is not possible to send the TSO segment on the
+			 * best subflow right now try to look for another subflow.
+			 * If there is no subflow available defer the segment to avoid
+			 * the call to mptso_fragment.
+			 */
+			if (!push_one && !reinject && tcp_tso_should_defer(subsk, skb)) {
+				mpcb->noneligible |= mptcp_pi_to_flag(subtp->mptcp->path_index);
+				goto subflow;
+			}
+		}
+
+		limit = mss_now;
+		if (tso_segs > 1 && !tcp_urg_mode(meta_tp))
+			limit = tcp_mss_split_point(subsk, skb, mss_now,
+						    min_t(unsigned int,
+							  cwnd_quota,
+							  subsk->sk_gso_max_segs));
+
+		if (skb->len > limit &&
+		    unlikely(mptso_fragment(meta_sk, skb, limit, mss_now, gfp, reinject)))
+			break;
+
+		subskb = mptcp_skb_entail(subsk, skb, reinject);
+		if (!subskb)
+			break;
+
+		mpcb->noneligible = noneligible;
+		TCP_SKB_CB(skb)->when = tcp_time_stamp;
+		TCP_SKB_CB(subskb)->when = tcp_time_stamp;
+		if (unlikely(tcp_transmit_skb(subsk, subskb, 1, gfp))) {
+			mptcp_transmit_skb_failed(subsk, skb, subskb, reinject);
+			mpcb->noneligible |= mptcp_pi_to_flag(subtp->mptcp->path_index);
+			continue;
+		}
+
+		if (!reinject) {
+			mptcp_check_sndseq_wrap(meta_tp,
+						TCP_SKB_CB(skb)->end_seq -
+						TCP_SKB_CB(skb)->seq);
+			tcp_event_new_data_sent(meta_sk, skb);
+		}
+
+		tcp_minshall_update(meta_tp, mss_now, skb);
+		sent_pkts += tcp_skb_pcount(skb);
+		tcp_sk(subsk)->mptcp->sent_pkts += tcp_skb_pcount(skb);
+
+		mptcp_sub_event_new_data_sent(subsk, subskb, skb);
+
+		if (reinject > 0) {
+			__skb_unlink(skb, &mpcb->reinject_queue);
+			kfree_skb(skb);
+		}
+
+		if (push_one)
+			break;
+	}
+
+	mpcb->noneligible = 0;
+
+	if (likely(sent_pkts)) {
+		mptcp_for_each_sk(mpcb, subsk) {
+			subtp = tcp_sk(subsk);
+			if (subtp->mptcp->sent_pkts) {
+				if (tcp_in_cwnd_reduction(subsk))
+					subtp->prr_out += subtp->mptcp->sent_pkts;
+				tcp_cwnd_validate(subsk);
+				subtp->mptcp->sent_pkts = 0;
+			}
+		}
+		return 0;
+	}
+
+	return !meta_tp->packets_out && tcp_send_head(meta_sk);
+}
+
+void mptcp_write_space(struct sock *sk)
+{
+	mptcp_push_pending_frames(mptcp_meta_sk(sk));
+}
+
+u32 __mptcp_select_window(struct sock *sk)
+{
+	struct inet_connection_sock *icsk = inet_csk(sk);
+	struct tcp_sock *tp = tcp_sk(sk), *meta_tp = mptcp_meta_tp(tp);
+	int mss, free_space, full_space, window;
+
+	/* MSS for the peer's data.  Previous versions used mss_clamp
+	 * here.  I don't know if the value based on our guesses
+	 * of peer's MSS is better for the performance.  It's more correct
+	 * but may be worse for the performance because of rcv_mss
+	 * fluctuations.  --SAW  1998/11/1
+	 */
+	mss = icsk->icsk_ack.rcv_mss;
+	free_space = tcp_space(sk);
+	full_space = min_t(int, meta_tp->window_clamp,
+			tcp_full_space(sk));
+
+	if (mss > full_space)
+		mss = full_space;
+
+	if (free_space < (full_space >> 1)) {
+		icsk->icsk_ack.quick = 0;
+
+		if (tcp_memory_pressure)
+			/* TODO this has to be adapted when we support different
+			 * MSS's among the subflows.
+			 */
+			meta_tp->rcv_ssthresh = min(meta_tp->rcv_ssthresh,
+						    4U * meta_tp->advmss);
+
+		if (free_space < mss)
+			return 0;
+	}
+
+	if (free_space > meta_tp->rcv_ssthresh)
+		free_space = meta_tp->rcv_ssthresh;
+
+	/* Don't do rounding if we are using window scaling, since the
+	 * scaled window will not line up with the MSS boundary anyway.
+	 */
+	window = meta_tp->rcv_wnd;
+	if (tp->rx_opt.rcv_wscale) {
+		window = free_space;
+
+		/* Advertise enough space so that it won't get scaled away.
+		 * Import case: prevent zero window announcement if
+		 * 1<<rcv_wscale > mss.
+		 */
+		if (((window >> tp->rx_opt.rcv_wscale) << tp->
+		     rx_opt.rcv_wscale) != window)
+			window = (((window >> tp->rx_opt.rcv_wscale) + 1)
+				  << tp->rx_opt.rcv_wscale);
+	} else {
+		/* Get the largest window that is a nice multiple of mss.
+		 * Window clamp already applied above.
+		 * If our current window offering is within 1 mss of the
+		 * free space we just keep it. This prevents the divide
+		 * and multiply from happening most of the time.
+		 * We also don't do any window rounding when the free space
+		 * is too small.
+		 */
+		if (window <= free_space - mss || window > free_space)
+			window = (free_space / mss) * mss;
+		else if (mss == full_space &&
+			 free_space > window + (full_space >> 1))
+			window = free_space;
+	}
+
+	return window;
+}
+
+static void mptcp_set_nonce(struct sock *sk)
+{
+	struct tcp_sock *tp = tcp_sk(sk);
+	struct inet_sock *inet = inet_sk(sk);
+
+	if (sk->sk_family == AF_INET)
+		tp->mptcp->mptcp_loc_nonce = mptcp_v4_get_nonce(inet->inet_saddr,
+								inet->inet_daddr,
+								inet->inet_sport,
+								inet->inet_dport,
+								tp->write_seq);
+#if IS_ENABLED(CONFIG_IPV6)
+	else
+		tp->mptcp->mptcp_loc_nonce = mptcp_v6_get_nonce(inet6_sk(sk)->saddr.s6_addr32,
+				     	     	     	        inet6_sk(sk)->daddr.s6_addr32,
+				     	     	     	        inet->inet_sport,
+				     	     	     	        inet->inet_dport,
+				     	     	     	        tp->write_seq);
+#endif
+
+	tp->mptcp->nonce_set = 1;
+}
+
+void mptcp_syn_options(struct sock *sk, struct tcp_out_options *opts,
+		       unsigned *remaining)
+{
+	struct tcp_sock *tp = tcp_sk(sk);
+
+	opts->options |= OPTION_MPTCP;
+	if (is_master_tp(tp)) {
+		opts->mptcp_options |= OPTION_MP_CAPABLE | OPTION_TYPE_SYN;
+		*remaining -= MPTCP_SUB_LEN_CAPABLE_SYN_ALIGN;
+		opts->mp_capable.sender_key = tp->mptcp_loc_key;
+		opts->dss_csum = sysctl_mptcp_checksum;
+
+		/* We arrive here either when sending a SYN or a
+		 * SYN+ACK when in SYN_SENT state (that is, tcp_synack_options
+		 * is only called for syn+ack replied by a server, while this
+		 * function is called when SYNs are sent by both parties and
+		 * are crossed)
+		 * Due to this possibility, a slave subsocket may arrive here,
+		 * and does not need to set the dataseq options, since
+		 * there is no data in the segment
+		 */
+	} else {
+		struct mptcp_cb *mpcb = tp->mpcb;
+
+		opts->mptcp_options |= OPTION_MP_JOIN | OPTION_TYPE_SYN;
+		*remaining -= MPTCP_SUB_LEN_JOIN_SYN_ALIGN;
+		opts->mp_join_syns.token = mpcb->mptcp_rem_token;
+		opts->addr_id = mptcp_get_loc_addrid(mpcb, sk);
+
+		if (!tp->mptcp->nonce_set)
+			mptcp_set_nonce(sk);
+
+		opts->mp_join_syns.sender_nonce = tp->mptcp->mptcp_loc_nonce;
+	}
+}
+
+void mptcp_synack_options(struct request_sock *req,
+			  struct tcp_out_options *opts, unsigned *remaining)
+{
+	struct mptcp_request_sock *mtreq;
+	mtreq = mptcp_rsk(req);
+
+	opts->options |= OPTION_MPTCP;
+	/* MPCB not yet set - thus it's a new MPTCP-session */
+	if (!mtreq->mpcb) {
+		opts->mptcp_options |= OPTION_MP_CAPABLE | OPTION_TYPE_SYNACK;
+		*remaining -= MPTCP_SUB_LEN_CAPABLE_SYN_ALIGN;
+		opts->mp_capable.sender_key = mtreq->mptcp_loc_key;
+		opts->dss_csum = sysctl_mptcp_checksum || mtreq->dss_csum;
+	} else {
+		struct inet_request_sock *ireq = inet_rsk(req);
+		int i;
+
+		opts->mptcp_options |= OPTION_MP_JOIN | OPTION_TYPE_SYNACK;
+		opts->mp_join_syns.sender_truncated_mac =
+				mtreq->mptcp_hash_tmac;
+		opts->mp_join_syns.sender_nonce = mtreq->mptcp_loc_nonce;
+		opts->addr_id = 0;
+
+		/* Finding Address ID */
+		if (req->rsk_ops->family == AF_INET)
+			mptcp_for_each_bit_set(mtreq->mpcb->loc4_bits, i) {
+				struct mptcp_loc4 *addr =
+						&mtreq->mpcb->locaddr4[i];
+				if (addr->addr.s_addr == ireq->loc_addr)
+					opts->addr_id = addr->id;
+			}
+#if IS_ENABLED(CONFIG_IPV6)
+		else /* IPv6 */
+			mptcp_for_each_bit_set(mtreq->mpcb->loc6_bits, i) {
+				struct mptcp_loc6 *addr =
+						&mtreq->mpcb->locaddr6[i];
+				if (ipv6_addr_equal(&addr->addr,
+						    &inet6_rsk(req)->loc_addr))
+					opts->addr_id = addr->id;
+			}
+#endif /* CONFIG_IPV6 */
+		*remaining -= MPTCP_SUB_LEN_JOIN_SYNACK_ALIGN;
+	}
+}
+
+void mptcp_established_options(struct sock *sk, struct sk_buff *skb,
+			       struct tcp_out_options *opts, unsigned *size)
+{
+	struct tcp_sock *tp = tcp_sk(sk), *meta_tp = mptcp_meta_tp(tp);
+	struct mptcp_cb *mpcb = tp->mpcb;
+	struct tcp_skb_cb *tcb = skb ? TCP_SKB_CB(skb) : NULL;
+
+	/* In fallback mp_fail-mode, we have to repeat it until the fallback
+	 * has been done by the sender
+	 */
+	if (unlikely(tp->mptcp->send_mp_fail)) {
+		opts->options |= OPTION_MPTCP;
+		opts->mptcp_options |= OPTION_MP_FAIL;
+		opts->data_ack = (__u32)(mpcb->csum_cutoff_seq >> 32);
+		opts->data_seq = (__u32)mpcb->csum_cutoff_seq;
+		*size += MPTCP_SUB_LEN_FAIL;
+		return;
+	}
+
+	if (unlikely(tp->send_mp_fclose)) {
+		opts->options |= OPTION_MPTCP;
+		opts->mptcp_options |= OPTION_MP_FCLOSE;
+		opts->mp_capable.receiver_key = mpcb->mptcp_rem_key;
+		*size += MPTCP_SUB_LEN_FCLOSE_ALIGN;
+		return;
+	}
+
+	/* 1. If we are the sender of the infinite-mapping, we need the
+	 *    MPTCPHDR_INF-flag, because a retransmission of the
+	 *    infinite-announcment still needs the mptcp-option.
+	 *
+	 *    We need infinite_cutoff_seq, because retransmissions from before
+	 *    the infinite-cutoff-moment still need the MPTCP-signalling to stay
+	 *    consistent.
+	 *
+	 * 2. If we are the receiver of the infinite-mapping, we always skip
+	 *    mptcp-options, because acknowledgments from before the
+	 *    infinite-mapping point have already been sent out.
+	 *
+	 * I know, the whole infinite-mapping stuff is ugly...
+	 *
+	 * TODO: Handle wrapped data-sequence numbers
+	 *       (even if it's very unlikely)
+	 */
+	if (unlikely(mpcb->infinite_mapping_snd) &&
+	    tp->mptcp->fully_established &&
+	    ((mpcb->send_infinite_mapping && tcb &&
+	      !(tcb->mptcp_flags & MPTCPHDR_INF) &&
+	      !before(tcb->seq, tp->mptcp->infinite_cutoff_seq)) ||
+	     !mpcb->send_infinite_mapping))
+		return;
+
+	if (unlikely(tp->mptcp->include_mpc)) {
+		opts->options |= OPTION_MPTCP;
+		opts->mptcp_options |= OPTION_MP_CAPABLE |
+				       OPTION_TYPE_ACK;
+		*size += MPTCP_SUB_LEN_CAPABLE_ACK_ALIGN;
+		opts->mp_capable.sender_key = mpcb->mptcp_loc_key;
+		opts->mp_capable.receiver_key = mpcb->mptcp_rem_key;
+		opts->dss_csum = mpcb->dss_csum;
+
+		if (skb)
+			tp->mptcp->include_mpc = 0;
+	}
+	if (unlikely(tp->mptcp->pre_established)) {
+		opts->options |= OPTION_MPTCP;
+		opts->mptcp_options |= OPTION_MP_JOIN | OPTION_TYPE_ACK;
+		*size += MPTCP_SUB_LEN_JOIN_ACK_ALIGN;
+	}
+
+	if (!tp->mptcp_add_addr_ack && !tp->mptcp->include_mpc &&
+	    !tp->mptcp->pre_established) {
+		opts->options |= OPTION_MPTCP;
+		opts->mptcp_options |= OPTION_DATA_ACK;
+		/* If !skb, we come from tcp_current_mss and thus we always
+		 * assume that the DSS-option will be set for the data-packet.
+		 */
+		if (skb && !mptcp_is_data_seq(skb)) {
+			opts->data_ack = meta_tp->rcv_nxt;
+
+			*size += MPTCP_SUB_LEN_ACK_ALIGN;
+		} else {
+			opts->data_ack = meta_tp->rcv_nxt;
+
+			/* Doesn't matter, if csum included or not. It will be
+			 * either 10 or 12, and thus aligned = 12
+			 */
+			*size += MPTCP_SUB_LEN_ACK_ALIGN +
+				 MPTCP_SUB_LEN_SEQ_ALIGN;
+		}
+
+		*size += MPTCP_SUB_LEN_DSS_ALIGN;
+	}
+
+	if (unlikely(tp->mptcp->add_addr4) &&
+	    MAX_TCP_OPTION_SPACE - *size >= MPTCP_SUB_LEN_ADD_ADDR4_ALIGN) {
+		int ind = mptcp_find_free_index(~(tp->mptcp->add_addr4));
+		opts->options |= OPTION_MPTCP;
+		opts->mptcp_options |= OPTION_ADD_ADDR;
+		opts->addr4 = &mpcb->locaddr4[ind];
+		if (skb)
+			tp->mptcp->add_addr4 &= ~(1 << ind);
+		*size += MPTCP_SUB_LEN_ADD_ADDR4_ALIGN;
+	} else if (unlikely(tp->mptcp->add_addr6) &&
+		   MAX_TCP_OPTION_SPACE - *size >= MPTCP_SUB_LEN_ADD_ADDR6_ALIGN) {
+		int ind = mptcp_find_free_index(~(tp->mptcp->add_addr6));
+		opts->options |= OPTION_MPTCP;
+		opts->mptcp_options |= OPTION_ADD_ADDR;
+		opts->addr6 = &mpcb->locaddr6[ind];
+		if (skb)
+			tp->mptcp->add_addr6 &= ~(1 << ind);
+		*size += MPTCP_SUB_LEN_ADD_ADDR6_ALIGN;
+	} else if (unlikely(mpcb->remove_addrs) &&
+		   MAX_TCP_OPTION_SPACE - *size >=
+		   mptcp_sub_len_remove_addr_align(mpcb->remove_addrs)) {
+		opts->options |= OPTION_MPTCP;
+		opts->mptcp_options |= OPTION_REMOVE_ADDR;
+		opts->remove_addrs = mpcb->remove_addrs;
+		*size += mptcp_sub_len_remove_addr_align(opts->remove_addrs);
+		if (skb)
+			mpcb->remove_addrs = 0;
+	} else if (!(opts->mptcp_options & OPTION_MP_CAPABLE) &&
+		   !(opts->mptcp_options & OPTION_MP_JOIN) &&
+		   ((unlikely(tp->mptcp->add_addr6) &&
+		     MAX_TCP_OPTION_SPACE - *size <=
+		     MPTCP_SUB_LEN_ADD_ADDR6_ALIGN) ||
+		    (unlikely(tp->mptcp->add_addr4) &&
+		     MAX_TCP_OPTION_SPACE - *size >=
+		     MPTCP_SUB_LEN_ADD_ADDR4_ALIGN))) {
+		mptcp_debug("no space for add addr. unsent IPv4: %#x,IPv6: %#x\n",
+			    tp->mptcp->add_addr4, tp->mptcp->add_addr6);
+		tp->mptcp_add_addr_ack = 1;
+		tcp_send_ack(sk);
+		tp->mptcp_add_addr_ack = 0;
+	}
+
+	if (unlikely(tp->mptcp->send_mp_prio) &&
+	    MAX_TCP_OPTION_SPACE - *size >= MPTCP_SUB_LEN_PRIO_ALIGN) {
+		opts->options |= OPTION_MPTCP;
+		opts->mptcp_options |= OPTION_MP_PRIO;
+		if (skb)
+			tp->mptcp->send_mp_prio = 0;
+		*size += MPTCP_SUB_LEN_PRIO_ALIGN;
+	}
+
+	return;
+}
+
+void mptcp_options_write(__be32 *ptr, struct tcp_sock *tp,
+			 struct tcp_out_options *opts,
+			 struct sk_buff *skb)
+{
+	if (unlikely(OPTION_MP_CAPABLE & opts->mptcp_options)) {
+		struct mp_capable *mpc = (struct mp_capable *)ptr;
+
+		mpc->kind = TCPOPT_MPTCP;
+
+		if ((OPTION_TYPE_SYN & opts->mptcp_options) ||
+		    (OPTION_TYPE_SYNACK & opts->mptcp_options)) {
+			mpc->sender_key = opts->mp_capable.sender_key;
+			mpc->len = MPTCP_SUB_LEN_CAPABLE_SYN;
+			ptr += MPTCP_SUB_LEN_CAPABLE_SYN_ALIGN >> 2;
+		} else if (OPTION_TYPE_ACK & opts->mptcp_options) {
+			mpc->sender_key = opts->mp_capable.sender_key;
+			mpc->receiver_key = opts->mp_capable.receiver_key;
+			mpc->len = MPTCP_SUB_LEN_CAPABLE_ACK;
+			ptr += MPTCP_SUB_LEN_CAPABLE_ACK_ALIGN >> 2;
+		}
+
+		mpc->sub = MPTCP_SUB_CAPABLE;
+		mpc->ver = 0;
+		mpc->a = opts->dss_csum ? 1 : 0;
+		mpc->b = 0;
+		mpc->rsv = 0;
+		mpc->h = 1;
+	}
+
+	if (unlikely(OPTION_MP_JOIN & opts->mptcp_options)) {
+		struct mp_join *mpj = (struct mp_join *)ptr;
+
+		mpj->kind = TCPOPT_MPTCP;
+		mpj->sub = MPTCP_SUB_JOIN;
+		mpj->rsv = 0;
+		mpj->addr_id = opts->addr_id;
+
+		if (OPTION_TYPE_SYN & opts->mptcp_options) {
+			mpj->len = MPTCP_SUB_LEN_JOIN_SYN;
+			mpj->u.syn.token = opts->mp_join_syns.token;
+			mpj->u.syn.nonce = opts->mp_join_syns.sender_nonce;
+			mpj->b = tp->mptcp->low_prio;
+			ptr += MPTCP_SUB_LEN_JOIN_SYN_ALIGN >> 2;
+		} else if (OPTION_TYPE_SYNACK & opts->mptcp_options) {
+			mpj->len = MPTCP_SUB_LEN_JOIN_SYNACK;
+			mpj->u.synack.mac =
+				opts->mp_join_syns.sender_truncated_mac;
+			mpj->u.synack.nonce = opts->mp_join_syns.sender_nonce;
+			mpj->b = tp->mptcp->low_prio;
+			ptr += MPTCP_SUB_LEN_JOIN_SYNACK_ALIGN >> 2;
+		} else if (OPTION_TYPE_ACK & opts->mptcp_options) {
+			mpj->len = MPTCP_SUB_LEN_JOIN_ACK;
+			memcpy(mpj->u.ack.mac, &tp->mptcp->sender_mac[0], 20);
+			ptr += MPTCP_SUB_LEN_JOIN_ACK_ALIGN >> 2;
+		}
+	}
+	if (unlikely(OPTION_ADD_ADDR & opts->mptcp_options)) {
+		struct mp_add_addr *mpadd = (struct mp_add_addr *)ptr;
+
+		mpadd->kind = TCPOPT_MPTCP;
+		if (opts->addr4) {
+			mpadd->len = MPTCP_SUB_LEN_ADD_ADDR4;
+			mpadd->sub = MPTCP_SUB_ADD_ADDR;
+			mpadd->ipver = 4;
+			mpadd->addr_id = opts->addr4->id;
+			mpadd->u.v4.addr = opts->addr4->addr;
+			ptr += MPTCP_SUB_LEN_ADD_ADDR4_ALIGN >> 2;
+		} else if (opts->addr6) {
+			mpadd->len = MPTCP_SUB_LEN_ADD_ADDR6;
+			mpadd->sub = MPTCP_SUB_ADD_ADDR;
+			mpadd->ipver = 6;
+			mpadd->addr_id = opts->addr6->id;
+			memcpy(&mpadd->u.v6.addr, &opts->addr6->addr,
+			       sizeof(mpadd->u.v6.addr));
+			ptr += MPTCP_SUB_LEN_ADD_ADDR6_ALIGN >> 2;
+		} else {
+			BUG();
+		}
+	}
+	if (unlikely(OPTION_REMOVE_ADDR & opts->mptcp_options)) {
+		struct mp_remove_addr *mprem = (struct mp_remove_addr *)ptr;
+		u8 *addrs_id;
+		int id, len, len_align;
+
+		len = mptcp_sub_len_remove_addr(opts->remove_addrs);
+		len_align = mptcp_sub_len_remove_addr_align(opts->remove_addrs);
+
+		mprem->kind = TCPOPT_MPTCP;
+		mprem->len = len;
+		mprem->sub = MPTCP_SUB_REMOVE_ADDR;
+		mprem->rsv = 0;
+		addrs_id = &mprem->addrs_id;
+
+		mptcp_for_each_bit_set(opts->remove_addrs, id)
+			*(addrs_id++) = id;
+
+		/* Fill the rest with NOP's */
+		if (len_align > len) {
+			int i;
+			for (i = 0; i < len_align - len; i++)
+				*(addrs_id++) = TCPOPT_NOP;
+		}
+
+		ptr += len_align >> 2;
+	}
+	if (unlikely(OPTION_MP_FAIL & opts->mptcp_options)) {
+		struct mp_fail *mpfail = (struct mp_fail *)ptr;
+
+		mpfail->kind = TCPOPT_MPTCP;
+		mpfail->len = MPTCP_SUB_LEN_FAIL;
+		mpfail->sub = MPTCP_SUB_FAIL;
+		mpfail->rsv1 = 0;
+		mpfail->rsv2 = 0;
+		mpfail->data_seq = htonll(((u64)opts->data_ack << 32) | opts->data_seq);
+
+		ptr += MPTCP_SUB_LEN_FAIL_ALIGN >> 2;
+	}
+	if (unlikely(OPTION_MP_FCLOSE & opts->mptcp_options)) {
+		struct mp_fclose *mpfclose = (struct mp_fclose *)ptr;
+
+		mpfclose->kind = TCPOPT_MPTCP;
+		mpfclose->len = MPTCP_SUB_LEN_FCLOSE;
+		mpfclose->sub = MPTCP_SUB_FCLOSE;
+		mpfclose->rsv1 = 0;
+		mpfclose->rsv2 = 0;
+		mpfclose->key = opts->mp_capable.receiver_key;
+
+		ptr += MPTCP_SUB_LEN_FCLOSE_ALIGN >> 2;
+	}
+
+	if (OPTION_DATA_ACK & opts->mptcp_options) {
+		if (!mptcp_is_data_seq(skb)) {
+			struct mp_dss *mdss = (struct mp_dss *)ptr;
+
+			mdss->kind = TCPOPT_MPTCP;
+			mdss->sub = MPTCP_SUB_DSS;
+			mdss->rsv1 = 0;
+			mdss->rsv2 = 0;
+			mdss->F = 0;
+			mdss->m = 0;
+			mdss->M = 0;
+			mdss->a = 0;
+			mdss->A = 1;
+			mdss->len = mptcp_sub_len_dss(mdss, tp->mpcb->dss_csum);
+
+			ptr++;
+			*ptr++ = htonl(opts->data_ack);
+		} else {
+			/**** Just update the data_ack ****/
+
+			/* Get pointer to data_ack-field. MPTCP is always at
+			 * the end of the TCP-options.
+			 */
+			/* TODO if we allow sending 64-bit dseq's we have to change "16" */
+			__be32 *dack = (__be32 *)(skb->data + (tcp_hdr(skb)->doff << 2) - 16);
+
+			*dack = htonl(opts->data_ack);
+		}
+	}
+	if (unlikely(OPTION_MP_PRIO & opts->mptcp_options)) {
+		struct mp_prio *mpprio = (struct mp_prio *)ptr;
+
+		mpprio->kind = TCPOPT_MPTCP;
+		mpprio->len = MPTCP_SUB_LEN_PRIO;
+		mpprio->sub = MPTCP_SUB_PRIO;
+		mpprio->rsv = 0;
+		mpprio->b = tp->mptcp->low_prio;
+		mpprio->addr_id = TCPOPT_NOP;
+
+		ptr += MPTCP_SUB_LEN_PRIO_ALIGN >> 2;
+	}
+}
+
+/* Returns the next segment to be sent from the mptcp meta-queue.
+ * (chooses the reinject queue if any segment is waiting in it, otherwise,
+ * chooses the normal write queue).
+ * Sets *@reinject to 1 if the returned segment comes from the
+ * reinject queue. Sets it to 0 if it is the regular send-head of the meta-sk,
+ * and sets it to -1 if it is a meta-level retransmission to optimize the
+ * receive-buffer.
+ */
+struct sk_buff *mptcp_next_segment(struct sock *meta_sk, int *reinject)
+{
+	struct mptcp_cb *mpcb = tcp_sk(meta_sk)->mpcb;
+	struct sk_buff *skb = NULL;
+	if (reinject)
+		*reinject = 0;
+
+	/* If we are in fallback-mode, just take from the meta-send-queue */
+	if (mpcb->infinite_mapping_snd || mpcb->send_infinite_mapping)
+		return tcp_send_head(meta_sk);
+
+	skb = skb_peek(&mpcb->reinject_queue);
+
+	if (skb) {
+		if (reinject)
+			*reinject = 1;
+	} else {
+		skb = tcp_send_head(meta_sk);
+
+		if (!skb && meta_sk->sk_write_pending &&
+		    sk_stream_wspace(meta_sk) < sk_stream_min_wspace(meta_sk)) {
+			struct sock *subsk = get_available_subflow(meta_sk, NULL, NULL);
+			if (!subsk)
+				return NULL;
+
+			skb = mptcp_rcv_buf_optimization(subsk, 0);
+			if (skb && reinject)
+				*reinject = -1;
+		}
+	}
+	return skb;
+}
+
+/* Sends the datafin */
+void mptcp_send_fin(struct sock *meta_sk)
+{
+	struct tcp_sock *meta_tp = tcp_sk(meta_sk);
+	struct sk_buff *skb = tcp_write_queue_tail(meta_sk);
+	int mss_now;
+
+	if ((1 << meta_sk->sk_state) & (TCPF_CLOSE_WAIT | TCPF_LAST_ACK))
+		meta_tp->mpcb->passive_close = 1;
+
+	/* Optimization, tack on the FIN if we have a queue of
+	 * unsent frames.  But be careful about outgoing SACKS
+	 * and IP options.
+	 */
+	mss_now = mptcp_current_mss(meta_sk);
+
+	if (tcp_send_head(meta_sk) != NULL) {
+		TCP_SKB_CB(skb)->mptcp_flags |= MPTCPHDR_FIN;
+		TCP_SKB_CB(skb)->end_seq++;
+		meta_tp->write_seq++;
+	} else {
+		/* Socket is locked, keep trying until memory is available. */
+		for (;;) {
+			skb = alloc_skb_fclone(MAX_TCP_HEADER,
+					       meta_sk->sk_allocation);
+			if (skb)
+				break;
+			yield();
+		}
+		/* Reserve space for headers and prepare control bits. */
+		skb_reserve(skb, MAX_TCP_HEADER);
+
+		tcp_init_nondata_skb(skb, meta_tp->write_seq, TCPHDR_ACK);
+		TCP_SKB_CB(skb)->end_seq++;
+		TCP_SKB_CB(skb)->mptcp_flags |= MPTCPHDR_FIN | MPTCPHDR_SEQ;
+		tcp_queue_skb(meta_sk, skb);
+	}
+	__tcp_push_pending_frames(meta_sk, mss_now, TCP_NAGLE_OFF);
+}
+
+void mptcp_send_active_reset(struct sock *meta_sk, gfp_t priority)
+{
+	struct tcp_sock *meta_tp = tcp_sk(meta_sk);
+	struct mptcp_cb *mpcb = meta_tp->mpcb;
+	struct sock *sk = NULL, *sk_it = NULL, *tmpsk;
+
+	if (!mpcb->cnt_subflows)
+		return;
+
+	/* First - select a socket */
+
+	/* Socket already selected? */
+	mptcp_for_each_sk(mpcb, sk_it) {
+		if (tcp_sk(sk_it)->send_mp_fclose) {
+			sk = sk_it;
+			goto found;
+		}
+	}
+
+	sk = mptcp_select_ack_sock(meta_sk, 0);
+	/* May happen if no subflow is in an appropriate state */
+	if (!sk)
+		return;
+
+	/* We are in infinite mode - just send a reset */
+	if (mpcb->infinite_mapping_snd || mpcb->infinite_mapping_rcv) {
+		tcp_send_active_reset(sk, priority);
+		return;
+	}
+
+	tcp_sk(sk)->send_mp_fclose = 1;
+
+	/** Reset all other subflows */
+
+found:
+	/* tcp_done must be handled with bh disabled */
+	if (!in_serving_softirq())
+		local_bh_disable();
+	mptcp_for_each_sk_safe(mpcb, sk_it, tmpsk) {
+		if (tcp_sk(sk_it)->send_mp_fclose)
+			continue;
+
+		sk_it->sk_err = ECONNRESET;
+		if (tcp_need_reset(sk_it->sk_state))
+			tcp_send_active_reset(sk_it, GFP_ATOMIC);
+		mptcp_sub_force_close(sk_it);
+	}
+	if (!in_serving_softirq())
+		local_bh_enable();
+
+	tcp_send_ack(sk);
+
+	if (!meta_tp->send_mp_fclose) {
+		struct inet_connection_sock *meta_icsk = inet_csk(meta_sk);
+
+		meta_icsk->icsk_rto = min(inet_csk(sk)->icsk_rto, TCP_RTO_MAX);
+		inet_csk_reset_xmit_timer(meta_sk, ICSK_TIME_RETRANS,
+					  meta_icsk->icsk_rto, TCP_RTO_MAX);
+	}
+
+	meta_tp->send_mp_fclose = 1;
+}
+
+void mptcp_ack_retransmit_timer(struct sock *sk)
+{
+	struct sk_buff *skb;
+	struct tcp_sock *tp = tcp_sk(sk);
+	struct inet_connection_sock *icsk = inet_csk(sk);
+
+	if (inet_csk(sk)->icsk_af_ops->rebuild_header(sk))
+		goto out; /* Routing failure or similar */
+
+	if (!tp->retrans_stamp)
+		tp->retrans_stamp = tcp_time_stamp ? : 1;
+
+	if (tcp_write_timeout(sk)) {
+		tp->mptcp->pre_established = 0;
+		sk_stop_timer(sk, &tp->mptcp->mptcp_ack_timer);
+		tcp_send_active_reset(sk, GFP_ATOMIC);
+		goto out;
+	}
+
+	skb = alloc_skb(MAX_TCP_HEADER, GFP_ATOMIC);
+	if (skb == NULL) {
+		sk_reset_timer(sk, &tp->mptcp->mptcp_ack_timer,
+			       jiffies + icsk->icsk_rto);
+		return;
+	}
+
+	/* Reserve space for headers and prepare control bits */
+	skb_reserve(skb, MAX_TCP_HEADER);
+	tcp_init_nondata_skb(skb, tp->snd_una, TCPHDR_ACK);
+
+	TCP_SKB_CB(skb)->when = tcp_time_stamp;
+	if (tcp_transmit_skb(sk, skb, 0, GFP_ATOMIC) > 0) {
+		/* Retransmission failed because of local congestion,
+		 * do not backoff.
+		 */
+		if (!icsk->icsk_retransmits)
+			icsk->icsk_retransmits = 1;
+		sk_reset_timer(sk, &tp->mptcp->mptcp_ack_timer,
+			       jiffies + icsk->icsk_rto);
+		return;
+	}
+
+
+	icsk->icsk_retransmits++;
+	icsk->icsk_rto = min(icsk->icsk_rto << 1, TCP_RTO_MAX);
+	sk_reset_timer(sk, &tp->mptcp->mptcp_ack_timer,
+		       jiffies + icsk->icsk_rto);
+	if (retransmits_timed_out(sk, sysctl_tcp_retries1 + 1, 0, 0)) {
+		__sk_dst_reset(sk);
+	}
+
+out:;
+}
+
+void mptcp_ack_handler(unsigned long data)
+{
+	struct sock *sk = (struct sock *)data;
+	struct sock *meta_sk = mptcp_meta_sk(sk);
+
+	bh_lock_sock(meta_sk);
+	if (sock_owned_by_user(meta_sk)) {
+		/* Try again later */
+		sk_reset_timer(sk, &tcp_sk(sk)->mptcp->mptcp_ack_timer,
+			       jiffies + (HZ / 20));
+		goto out_unlock;
+	}
+
+	if (sk->sk_state == TCP_CLOSE)
+		goto out_unlock;
+
+	mptcp_ack_retransmit_timer(sk);
+
+	sk_mem_reclaim(sk);
+
+out_unlock:
+	bh_unlock_sock(meta_sk);
+	sock_put(sk);
+}
+
+/* Similar to tcp_retransmit_skb
+ *
+ * The diff is that we handle the retransmission-stats (retrans_stamp) at the
+ * meta-level.
+ */
+int mptcp_retransmit_skb(struct sock *meta_sk, struct sk_buff *skb)
+{
+	struct tcp_sock *meta_tp = tcp_sk(meta_sk);
+	struct sock *subsk;
+	struct sk_buff *subskb;
+	unsigned int limit, tso_segs, mss_now;
+	int err = -1, oldpcount;
+
+	/* Do not sent more than we queued. 1/4 is reserved for possible
+	 * copying overhead: fragmentation, tunneling, mangling etc.
+	 *
+	 * This is a meta-retransmission thus we check on the meta-socket.
+	 */
+	if (atomic_read(&meta_sk->sk_wmem_alloc) >
+	    min(meta_sk->sk_wmem_queued + (meta_sk->sk_wmem_queued >> 2), meta_sk->sk_sndbuf)) {
+		return -EAGAIN;
+	}
+
+	/* We need to make sure that the retransmitted segment can be sent on a
+	 * subflow right now. If it is too big, it needs to be fragmented.
+	 */
+	subsk = get_available_subflow(meta_sk, skb, &mss_now);
+	if (!subsk) {
+		/* We want to increase icsk_retransmits, thus return 0, so that
+		 * mptcp_retransmit_timer enters the desired branch.
+		 */
+		err = 0;
+		goto failed;
+	}
+
+	/* If the segment was cloned (e.g. a meta retransmission), the header
+	 * must be expanded/copied so that there is no corruption of TSO
+	 * information.
+	 */
+	if (skb_cloned(skb) && skb_is_nonlinear(skb) &&
+	    unlikely(pskb_expand_head(skb, 0, 0, GFP_ATOMIC))) {
+		err = ENOMEM;
+		goto failed;
+	}
+
+	oldpcount = tcp_skb_pcount(skb);
+	tso_segs = tcp_init_tso_segs(meta_sk, skb, mss_now);
+	BUG_ON(!tso_segs);
+
+	/* The MSS might have changed and so the number of segments. We
+	 * need to account for this change.
+	 */
+	if (unlikely(oldpcount != tso_segs))
+		tcp_adjust_pcount(meta_sk, skb, oldpcount - tso_segs);
+
+	limit = mss_now;
+	if (tso_segs > 1 && !tcp_urg_mode(meta_tp))
+		limit = tcp_mss_split_point(subsk, skb, mss_now,
+					    min_t(unsigned int,
+						  tcp_cwnd_test(tcp_sk(subsk), skb),
+						  subsk->sk_gso_max_segs));
+
+	if (skb->len > limit &&
+	    unlikely(mptso_fragment(meta_sk, skb, limit, mss_now,
+				    GFP_ATOMIC, 0)))
+		goto failed;
+
+	subskb = mptcp_skb_entail(subsk, skb, -1);
+	if (!subskb)
+		goto failed;
+
+	TCP_SKB_CB(skb)->when = tcp_time_stamp;
+	TCP_SKB_CB(subskb)->when = tcp_time_stamp;
+	err = tcp_transmit_skb(subsk, subskb, 1, GFP_ATOMIC);
+	if (!err) {
+		/* Update global TCP statistics. */
+		TCP_INC_STATS(sock_net(meta_sk), TCP_MIB_RETRANSSEGS);
+
+		/* Diff to tcp_retransmit_skb */
+
+		/* Save stamp of the first retransmit. */
+		if (!meta_tp->retrans_stamp)
+			meta_tp->retrans_stamp = TCP_SKB_CB(subskb)->when;
+		mptcp_sub_event_new_data_sent(subsk, subskb, skb);
+	} else {
+		mptcp_transmit_skb_failed(subsk, skb, subskb, 0);
+	}
+
+failed:
+	return err;
+}
+
+/* Similar to tcp_retransmit_timer
+ *
+ * The diff is that we have to handle retransmissions of the FAST_CLOSE-message
+ * and that we don't have an srtt estimation at the meta-level.
+ */
+void mptcp_retransmit_timer(struct sock *meta_sk)
+{
+	struct tcp_sock *meta_tp = tcp_sk(meta_sk);
+	struct mptcp_cb *mpcb = meta_tp->mpcb;
+	struct inet_connection_sock *meta_icsk = inet_csk(meta_sk);
+	int err;
+
+	if (unlikely(meta_tp->send_mp_fclose))
+		goto send_mp_fclose;
+
+	/* In fallback, retransmission is handled at the subflow-level */
+	if (!meta_tp->packets_out || mpcb->infinite_mapping_snd ||
+	    mpcb->send_infinite_mapping)
+		return;
+
+	WARN_ON(tcp_write_queue_empty(meta_sk));
+
+	if (!meta_tp->snd_wnd && !sock_flag(meta_sk, SOCK_DEAD) &&
+	    !((1 << meta_sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV))) {
+		/* Receiver dastardly shrinks window. Our retransmits
+		 * become zero probes, but we should not timeout this
+		 * connection. If the socket is an orphan, time it out,
+		 * we cannot allow such beasts to hang infinitely.
+		 */
+		struct inet_sock *meta_inet = inet_sk(meta_sk);
+		if (meta_sk->sk_family == AF_INET) {
+			LIMIT_NETDEBUG(KERN_DEBUG "TCP: Peer %pI4:%u/%u unexpectedly shrunk window %u:%u (repaired)\n",
+				       &meta_inet->inet_daddr,
+				       ntohs(meta_inet->inet_dport),
+				       meta_inet->inet_num, meta_tp->snd_una,
+				       meta_tp->snd_nxt);
+		}
+#if IS_ENABLED(CONFIG_IPV6)
+		else if (meta_sk->sk_family == AF_INET6) {
+			struct ipv6_pinfo *np = inet6_sk(meta_sk);
+			LIMIT_NETDEBUG(KERN_DEBUG "TCP: Peer %pI6:%u/%u unexpectedly shrunk window %u:%u (repaired)\n",
+				       &np->daddr, ntohs(meta_inet->inet_dport),
+				       meta_inet->inet_num, meta_tp->snd_una,
+				       meta_tp->snd_nxt);
+		}
+#endif
+		if (tcp_time_stamp - meta_tp->rcv_tstamp > TCP_RTO_MAX) {
+			tcp_write_err(meta_sk);
+			return;
+		}
+
+		mptcp_retransmit_skb(meta_sk, tcp_write_queue_head(meta_sk));
+		goto out_reset_timer;
+	}
+
+	if (tcp_write_timeout(meta_sk))
+		return;
+
+	if (meta_icsk->icsk_retransmits == 0)
+		NET_INC_STATS_BH(sock_net(meta_sk), LINUX_MIB_TCPTIMEOUTS);
+
+	meta_icsk->icsk_ca_state = TCP_CA_Loss;
+
+	err = mptcp_retransmit_skb(meta_sk, tcp_write_queue_head(meta_sk));
+	if (err > 0) {
+		/* Retransmission failed because of local congestion,
+		 * do not backoff.
+		 */
+		if (!meta_icsk->icsk_retransmits)
+			meta_icsk->icsk_retransmits = 1;
+		inet_csk_reset_xmit_timer(meta_sk, ICSK_TIME_RETRANS,
+					  min(meta_icsk->icsk_rto, TCP_RESOURCE_PROBE_INTERVAL),
+					  TCP_RTO_MAX);
+		return;
+	}
+
+out_backoff:
+	/* Increase the timeout each time we retransmit.  Note that
+	 * we do not increase the rtt estimate.  rto is initialized
+	 * from rtt, but increases here.  Jacobson (SIGCOMM 88) suggests
+	 * that doubling rto each time is the least we can get away with.
+	 * In KA9Q, Karn uses this for the first few times, and then
+	 * goes to quadratic.  netBSD doubles, but only goes up to *64,
+	 * and clamps at 1 to 64 sec afterwards.  Note that 120 sec is
+	 * defined in the protocol as the maximum possible RTT.  I guess
+	 * we'll have to use something other than TCP to talk to the
+	 * University of Mars.
+	 *
+	 * PAWS allows us longer timeouts and large windows, so once
+	 * implemented ftp to mars will work nicely. We will have to fix
+	 * the 120 second clamps though!
+	 */
+	meta_icsk->icsk_backoff++;
+	meta_icsk->icsk_retransmits++;
+
+out_reset_timer:
+	/* If stream is thin, use linear timeouts. Since 'icsk_backoff' is
+	 * used to reset timer, set to 0. Recalculate 'icsk_rto' as this
+	 * might be increased if the stream oscillates between thin and thick,
+	 * thus the old value might already be too high compared to the value
+	 * set by 'tcp_set_rto' in tcp_input.c which resets the rto without
+	 * backoff. Limit to TCP_THIN_LINEAR_RETRIES before initiating
+	 * exponential backoff behaviour to avoid continue hammering
+	 * linear-timeout retransmissions into a black hole
+	 */
+	if (meta_sk->sk_state == TCP_ESTABLISHED &&
+	    (meta_tp->thin_lto || sysctl_tcp_thin_linear_timeouts) &&
+	    tcp_stream_is_thin(meta_tp) &&
+	    meta_icsk->icsk_retransmits <= TCP_THIN_LINEAR_RETRIES) {
+		meta_icsk->icsk_backoff = 0;
+		/* We cannot do the same as in tcp_write_timer because the
+		 * srtt is not set here.
+		 */
+		mptcp_set_rto(meta_sk);
+	} else {
+		/* Use normal (exponential) backoff */
+		meta_icsk->icsk_rto = min(meta_icsk->icsk_rto << 1, TCP_RTO_MAX);
+	}
+	inet_csk_reset_xmit_timer(meta_sk, ICSK_TIME_RETRANS, meta_icsk->icsk_rto, TCP_RTO_MAX);
+
+	return;
+
+send_mp_fclose:
+	/* MUST do this before tcp_write_timeout, because retrans_stamp may have
+	 * been set to 0 in another part while we are retransmitting
+	 * MP_FASTCLOSE. Then, we would crash, because retransmits_timed_out
+	 * accesses the meta-write-queue.
+	 *
+	 * We make sure that the timestamp is != 0.
+	 */
+	if (!meta_tp->retrans_stamp)
+		meta_tp->retrans_stamp = tcp_time_stamp ? : 1;
+
+	if (tcp_write_timeout(meta_sk))
+		return;
+
+	mptcp_send_active_reset(meta_sk, GFP_ATOMIC);
+
+	goto out_backoff;
+}
+
+/* Modify values to an mptcp-level for the initial window of new subflows */
+void mptcp_select_initial_window(int *__space, __u32 *window_clamp,
+				 const struct sock *sk)
+{
+	struct mptcp_cb *mpcb = tcp_sk(sk)->mpcb;
+
+	*window_clamp = mpcb->orig_window_clamp;
+	*__space = tcp_win_from_space(mpcb->orig_sk_rcvbuf);
+}
+
+unsigned int mptcp_current_mss(struct sock *meta_sk)
+{
+	unsigned int mss = 0;
+	struct sock *sk;
+
+	mptcp_for_each_sk(tcp_sk(meta_sk)->mpcb, sk) {
+		int this_mss;
+
+		if (!mptcp_sk_can_send(sk))
+			continue;
+
+		this_mss = tcp_current_mss(sk);
+		if (!mss || this_mss < mss)
+			mss = this_mss;
+	}
+
+	/* If no subflow is available, we take a default-mss from the
+	 * meta-socket.
+	 */
+	return !mss ? tcp_current_mss(meta_sk) : mss;
+}
+
+int mptcp_select_size(const struct sock *meta_sk, bool sg)
+{
+	int mss = 0; /* We look for the smallest MSS */
+	struct sock *sk;
+
+	mptcp_for_each_sk(tcp_sk(meta_sk)->mpcb, sk) {
+		int this_mss;
+
+		if (!mptcp_sk_can_send(sk))
+			continue;
+
+		this_mss = tcp_sk(sk)->mss_cache;
+		if (!mss || this_mss < mss)
+			mss = this_mss;
+	}
+
+	if (sg) {
+		if (mptcp_sk_can_gso(meta_sk)) {
+			mss = SKB_WITH_OVERHEAD(2048 - MAX_TCP_HEADER);
+		} else {
+			int pgbreak = SKB_MAX_HEAD(MAX_TCP_HEADER);
+
+			if (mss >= pgbreak &&
+			    mss <= pgbreak + (MAX_SKB_FRAGS - 1) * PAGE_SIZE)
+				mss = pgbreak;
+		}
+	}
+
+	return !mss ? tcp_sk(meta_sk)->mss_cache : mss;
+}
+
+int mptcp_check_snd_buf(const struct tcp_sock *tp)
+{
+	struct sock *sk;
+	u32 rtt_max = tp->srtt;
+	u64 bw_est;
+
+	if (!tp->srtt)
+		return tp->reordering + 1;
+
+	mptcp_for_each_sk(tp->mpcb, sk) {
+		if (!mptcp_sk_can_send(sk))
+			continue;
+
+		if (rtt_max < tcp_sk(sk)->srtt)
+			rtt_max = tcp_sk(sk)->srtt;
+	}
+
+	bw_est = div64_u64(((u64)tp->snd_cwnd * rtt_max) << 16,
+				(u64)tp->srtt);
+
+	return max_t(unsigned int, (u32)(bw_est >> 16),
+			tp->reordering + 1);
+
+}
+
+unsigned int mptcp_xmit_size_goal(struct sock *meta_sk, u32 mss_now,
+				  int large_allowed)
+{
+	struct sock *sk;
+	u32 xmit_size_goal = 0;
+
+	if (large_allowed && mptcp_sk_can_gso(meta_sk)) {
+		mptcp_for_each_sk(tcp_sk(meta_sk)->mpcb, sk) {
+			int this_size_goal;
+
+			if (!mptcp_sk_can_send(sk))
+				continue;
+
+			this_size_goal = tcp_xmit_size_goal(sk, mss_now, 1);
+			if (!xmit_size_goal || this_size_goal < xmit_size_goal)
+				xmit_size_goal = this_size_goal;
+		}
+	}
+
+	return max(xmit_size_goal, mss_now);
+}
+
+/* Similar to tcp_trim_head - but we correctly copy the DSS-option */
+int mptcp_trim_head(struct sock *sk, struct sk_buff *skb, u32 len)
+{
+	int dsslen = MPTCP_SUB_LEN_DSS_ALIGN + MPTCP_SUB_LEN_ACK_ALIGN +
+		     MPTCP_SUB_LEN_SEQ_ALIGN;
+	char dss[dsslen];
+
+	/* DSS-option must be recovered afterwards. */
+	memcpy(dss, skb->data - dsslen, dsslen);
+
+	if (skb_cloned(skb)) {
+		/* pskb_expand_head will delete our DSS-option. We have to copy
+		 * it back if pskb_expand_head succeeds.
+		 */
+
+		if (pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
+			return -ENOMEM;
+
+		memcpy(skb->data - dsslen, dss, dsslen);
+	}
+
+	__pskb_trim_head(skb, len);
+
+	/* Put the DSS-option back in our header */
+	memcpy(skb->data - dsslen, dss, dsslen);
+
+	TCP_SKB_CB(skb)->seq += len;
+	skb->ip_summed = CHECKSUM_PARTIAL;
+
+	skb->truesize	     -= len;
+	sk->sk_wmem_queued   -= len;
+	sk_mem_uncharge(sk, len);
+	sock_set_flag(sk, SOCK_QUEUE_SHRUNK);
+
+	/* Any change of skb->len requires recalculation of tso factor. */
+	if (tcp_skb_pcount(skb) > 1)
+		tcp_set_skb_tso_segs(sk, skb, tcp_skb_mss(skb));
+
+	return 0;
+}
diff -Naur a/net/mptcp/mptcp_pm.c b/net/mptcp/mptcp_pm.c
--- a/net/mptcp/mptcp_pm.c	1970-01-01 01:00:00.000000000 +0100
+++ b/net/mptcp/mptcp_pm.c	2013-10-06 18:26:04.525865783 +0200
@@ -0,0 +1,1194 @@
+/*
+ *	MPTCP implementation - MPTCP-subflow-management
+ *
+ *	Initial Design & Implementation:
+ *	Sébastien Barré <[e-mail]>
+ *
+ *	Current Maintainer & Author:
+ *	Christoph Paasch <[e-mail]>
+ *
+ *	Additional authors:
+ *	Jaakko Korkeaniemi <[e-mail]>
+ *	Gregory Detal <[e-mail]>
+ *	Fabien Duchêne <[e-mail]>
+ *	Andreas Seelinger <[e-mail]>
+ *	Lavkesh Lahngir <[e-mail]>
+ *	Andreas Ripke <[e-mail]>
+ *	Vlad Dogaru <[e-mail]>
+ *	Octavian Purdila <[e-mail]>
+ *	John Ronan <[e-mail]>
+ *	Catalin Nicutar <[e-mail]>
+ *	Brandon Heller <[e-mail]>
+ *
+ *
+ *	This program is free software; you can redistribute it and/or
+ *      modify it under the terms of the GNU General Public License
+ *      as published by the Free Software Foundation; either version
+ *      2 of the License, or (at your option) any later version.
+ */
+
+#include <linux/kconfig.h>
+#include <linux/module.h>
+#include <linux/netdevice.h>
+#include <linux/inetdevice.h>
+#include <linux/list.h>
+#include <linux/tcp.h>
+#include <linux/workqueue.h>
+#include <linux/proc_fs.h>	/* Needed by proc_net_fops_create */
+#include <net/inet_sock.h>
+#include <net/tcp.h>
+#include <net/mptcp.h>
+#include <net/mptcp_v4.h>
+#include <net/mptcp_pm.h>
+#if IS_ENABLED(CONFIG_IPV6)
+#include <net/if_inet6.h>
+#include <net/ipv6.h>
+#include <net/ip6_checksum.h>
+#include <net/inet6_connection_sock.h>
+#include <net/mptcp_v6.h>
+#include <net/addrconf.h>
+#endif
+
+static inline u32 mptcp_hash_tk(u32 token)
+{
+	return token % MPTCP_HASH_SIZE;
+}
+
+static struct hlist_nulls_head tk_hashtable[MPTCP_HASH_SIZE];
+
+/* This second hashtable is needed to retrieve request socks
+ * created as a result of a join request. While the SYN contains
+ * the token, the final ack does not, so we need a separate hashtable
+ * to retrieve the mpcb.
+ */
+struct list_head mptcp_reqsk_htb[MPTCP_HASH_SIZE];
+spinlock_t mptcp_reqsk_hlock;	/* hashtable protection */
+
+/* The following hash table is used to avoid collision of token */
+static struct hlist_nulls_head mptcp_reqsk_tk_htb[MPTCP_HASH_SIZE];
+spinlock_t mptcp_tk_hashlock;	/* hashtable protection */
+
+static int mptcp_reqsk_find_tk(u32 token)
+{
+	u32 hash = mptcp_hash_tk(token);
+	struct mptcp_request_sock *mtreqsk;
+	const struct hlist_nulls_node *node;
+
+	hlist_nulls_for_each_entry_rcu(mtreqsk, node,
+				       &mptcp_reqsk_tk_htb[hash], collide_tk) {
+		if (token == mtreqsk->mptcp_loc_token)
+			return 1;
+	}
+	return 0;
+}
+
+static void mptcp_reqsk_insert_tk(struct request_sock *reqsk, u32 token)
+{
+	u32 hash = mptcp_hash_tk(token);
+
+	hlist_nulls_add_head_rcu(&mptcp_rsk(reqsk)->collide_tk,
+				 &mptcp_reqsk_tk_htb[hash]);
+}
+
+void mptcp_reqsk_remove_tk(struct request_sock *reqsk)
+{
+	rcu_read_lock();
+	spin_lock(&mptcp_tk_hashlock);
+	hlist_nulls_del_rcu(&mptcp_rsk(reqsk)->collide_tk);
+	spin_unlock(&mptcp_tk_hashlock);
+	rcu_read_unlock();
+}
+
+void __mptcp_hash_insert(struct tcp_sock *meta_tp, u32 token)
+{
+	u32 hash = mptcp_hash_tk(token);
+	hlist_nulls_add_head_rcu(&meta_tp->tk_table, &tk_hashtable[hash]);
+	meta_tp->inside_tk_table = 1;
+}
+
+static int mptcp_find_token(u32 token)
+{
+	u32 hash = mptcp_hash_tk(token);
+	struct tcp_sock *meta_tp;
+	const struct hlist_nulls_node *node;
+
+	hlist_nulls_for_each_entry_rcu(meta_tp, node, &tk_hashtable[hash], tk_table) {
+		if (token == meta_tp->mptcp_loc_token)
+			return 1;
+	}
+	return 0;
+}
+
+static void mptcp_set_key_reqsk(struct request_sock *req,
+				const struct sk_buff *skb)
+{
+	struct inet_request_sock *ireq = inet_rsk(req);
+	struct mptcp_request_sock *mtreq = mptcp_rsk(req);
+
+	if (skb->protocol == htons(ETH_P_IP)) {
+		mtreq->mptcp_loc_key = mptcp_v4_get_key(ip_hdr(skb)->saddr,
+						        ip_hdr(skb)->daddr,
+						        ireq->loc_port,
+						        ireq->rmt_port);
+#if IS_ENABLED(CONFIG_IPV6)
+	} else {
+		mtreq->mptcp_loc_key = mptcp_v6_get_key(ipv6_hdr(skb)->saddr.s6_addr32,
+							ipv6_hdr(skb)->daddr.s6_addr32,
+							ireq->loc_port,
+							ireq->rmt_port);
+#endif
+	}
+
+	mptcp_key_sha1(mtreq->mptcp_loc_key, &mtreq->mptcp_loc_token, NULL);
+}
+
+/* New MPTCP-connection request, prepare a new token for the meta-socket that
+ * will be created in mptcp_check_req_master(), and store the received token.
+ */
+void mptcp_reqsk_new_mptcp(struct request_sock *req,
+			   const struct tcp_options_received *rx_opt,
+			   const struct mptcp_options_received *mopt,
+			   const struct sk_buff *skb)
+{
+	struct mptcp_request_sock *mtreq = mptcp_rsk(req);
+
+	tcp_rsk(req)->saw_mpc = 1;
+
+	rcu_read_lock();
+	spin_lock(&mptcp_tk_hashlock);
+	do {
+		mptcp_set_key_reqsk(req, skb);
+	} while (mptcp_reqsk_find_tk(mtreq->mptcp_loc_token) ||
+		 mptcp_find_token(mtreq->mptcp_loc_token));
+
+	mptcp_reqsk_insert_tk(req, mtreq->mptcp_loc_token);
+	spin_unlock(&mptcp_tk_hashlock);
+	rcu_read_unlock();
+	mtreq->mptcp_rem_key = mopt->mptcp_key;
+}
+
+static void mptcp_set_key_sk(struct sock *sk)
+{
+	struct tcp_sock *tp = tcp_sk(sk);
+	struct inet_sock *isk = inet_sk(sk);
+
+	if (sk->sk_family == AF_INET)
+		tp->mptcp_loc_key = mptcp_v4_get_key(isk->inet_saddr,
+						     isk->inet_daddr,
+						     isk->inet_sport,
+						     isk->inet_dport);
+#if IS_ENABLED(CONFIG_IPV6)
+	else
+		tp->mptcp_loc_key = mptcp_v6_get_key(inet6_sk(sk)->saddr.s6_addr32,
+						     inet6_sk(sk)->daddr.s6_addr32,
+						     isk->inet_sport,
+						     isk->inet_dport);
+#endif
+
+	mptcp_key_sha1(tp->mptcp_loc_key,
+		       &tp->mptcp_loc_token, NULL);
+}
+
+void mptcp_connect_init(struct sock *sk)
+{
+	struct tcp_sock *tp = tcp_sk(sk);
+
+	rcu_read_lock_bh();
+	spin_lock(&mptcp_tk_hashlock);
+	do {
+		mptcp_set_key_sk(sk);
+	} while (mptcp_reqsk_find_tk(tp->mptcp_loc_token) ||
+		 mptcp_find_token(tp->mptcp_loc_token));
+
+	__mptcp_hash_insert(tp, tp->mptcp_loc_token);
+	spin_unlock(&mptcp_tk_hashlock);
+	rcu_read_unlock_bh();
+}
+
+/**
+ * This function increments the refcount of the mpcb struct.
+ * It is the responsibility of the caller to decrement when releasing
+ * the structure.
+ */
+struct sock *mptcp_hash_find(struct net *net, u32 token)
+{
+	u32 hash = mptcp_hash_tk(token);
+	struct tcp_sock *meta_tp;
+	struct sock *meta_sk = NULL;
+	struct hlist_nulls_node *node;
+
+	rcu_read_lock();
+	hlist_nulls_for_each_entry_rcu(meta_tp, node, &tk_hashtable[hash],
+				       tk_table) {
+		meta_sk = (struct sock *)meta_tp;
+		if (token == meta_tp->mptcp_loc_token &&
+		    net_eq(net, sock_net(meta_sk)) &&
+		    atomic_inc_not_zero(&meta_sk->sk_refcnt))
+			break;
+		meta_sk = NULL;
+	}
+	rcu_read_unlock();
+	return meta_sk;
+}
+
+void mptcp_hash_remove_bh(struct tcp_sock *meta_tp)
+{
+	/* remove from the token hashtable */
+	rcu_read_lock_bh();
+	spin_lock(&mptcp_tk_hashlock);
+	hlist_nulls_del_rcu(&meta_tp->tk_table);
+	meta_tp->inside_tk_table = 0;
+	spin_unlock(&mptcp_tk_hashlock);
+	rcu_read_unlock_bh();
+}
+
+void mptcp_hash_remove(struct tcp_sock *meta_tp)
+{
+	rcu_read_lock();
+	spin_lock(&mptcp_tk_hashlock);
+	hlist_nulls_del_rcu(&meta_tp->tk_table);
+	meta_tp->inside_tk_table = 0;
+	spin_unlock(&mptcp_tk_hashlock);
+	rcu_read_unlock();
+}
+
+u8 mptcp_get_loc_addrid(struct mptcp_cb *mpcb, struct sock *sk)
+{
+	int i;
+
+	if (sk->sk_family == AF_INET) {
+		mptcp_for_each_bit_set(mpcb->loc4_bits, i) {
+			if (mpcb->locaddr4[i].addr.s_addr ==
+					inet_sk(sk)->inet_saddr)
+				return mpcb->locaddr4[i].id;
+		}
+
+		mptcp_debug("%s %pI4 not locally found\n", __func__,
+			    &inet_sk(sk)->inet_saddr);
+		BUG();
+	}
+#if IS_ENABLED(CONFIG_IPV6)
+	if (sk->sk_family == AF_INET6) {
+		mptcp_for_each_bit_set(mpcb->loc6_bits, i) {
+			if (ipv6_addr_equal(&mpcb->locaddr6[i].addr,
+					    &inet6_sk(sk)->saddr))
+				return mpcb->locaddr6[i].id;
+		}
+
+		mptcp_debug("%s %pI6 not locally found\n", __func__,
+			    &inet6_sk(sk)->saddr);
+		BUG();
+	}
+#endif /* CONFIG_IPV6 */
+
+	BUG();
+	return 0;
+}
+
+void mptcp_set_addresses(struct sock *meta_sk)
+{
+	struct mptcp_cb *mpcb = tcp_sk(meta_sk)->mpcb;
+	struct net *netns = sock_net(meta_sk);
+	struct net_device *dev;
+
+	/* if multiports is requested, we work with the main address
+	 * and play only with the ports
+	 */
+	if (sysctl_mptcp_ndiffports > 1)
+		return;
+
+	rcu_read_lock();
+	read_lock_bh(&dev_base_lock);
+
+	for_each_netdev(netns, dev) {
+		if (netif_running(dev)) {
+			struct in_device *in_dev = __in_dev_get_rcu(dev);
+			struct in_ifaddr *ifa;
+			__be32 ifa_address;
+#if IS_ENABLED(CONFIG_IPV6)
+			struct inet6_dev *in6_dev = __in6_dev_get(dev);
+			struct inet6_ifaddr *ifa6;
+#endif
+
+			if (dev->flags & (IFF_LOOPBACK | IFF_NOMULTIPATH))
+				continue;
+
+			if (!in_dev)
+				goto cont_ipv6;
+
+			for (ifa = in_dev->ifa_list; ifa; ifa = ifa->ifa_next) {
+				int i;
+				ifa_address = ifa->ifa_local;
+
+				if (ifa->ifa_scope == RT_SCOPE_HOST)
+					continue;
+
+				if ((meta_sk->sk_family == AF_INET ||
+				     mptcp_v6_is_v4_mapped(meta_sk)) &&
+				    inet_sk(meta_sk)->inet_saddr == ifa_address) {
+					mpcb->locaddr4[0].low_prio = dev->flags &
+								IFF_MPBACKUP ? 1 : 0;
+					continue;
+				}
+
+				i = __mptcp_find_free_index(mpcb->loc4_bits, -1,
+							    mpcb->next_v4_index);
+				if (i < 0) {
+					mptcp_debug("%s: At max num of local addresses: %d --- not adding address: %pI4\n",
+						    __func__, MPTCP_MAX_ADDR,
+						    &ifa_address);
+					goto out;
+				}
+				mpcb->locaddr4[i].addr.s_addr = ifa_address;
+				mpcb->locaddr4[i].port = 0;
+				mpcb->locaddr4[i].id = i;
+				mpcb->locaddr4[i].low_prio = (dev->flags & IFF_MPBACKUP) ?
+								1 : 0;
+				mpcb->loc4_bits |= (1 << i);
+				mpcb->next_v4_index = i + 1;
+				mptcp_v4_send_add_addr(i, mpcb);
+			}
+
+cont_ipv6:
+; /* This ; is necessary to fix build-errors when IPv6 is disabled */
+#if IS_ENABLED(CONFIG_IPV6)
+			if (!in6_dev)
+				continue;
+
+			list_for_each_entry(ifa6, &in6_dev->addr_list, if_list) {
+				int addr_type = ipv6_addr_type(&ifa6->addr);
+				int i;
+
+				if (addr_type == IPV6_ADDR_ANY ||
+				    addr_type & IPV6_ADDR_LOOPBACK ||
+				    addr_type & IPV6_ADDR_LINKLOCAL)
+					continue;
+
+				if (meta_sk->sk_family == AF_INET6 &&
+				    ipv6_addr_equal(&inet6_sk(meta_sk)->saddr,
+						    &(ifa6->addr))) {
+					mpcb->locaddr6[0].low_prio = dev->flags &
+								IFF_MPBACKUP ? 1 : 0;
+					continue;
+				}
+
+				i = __mptcp_find_free_index(mpcb->loc6_bits, -1,
+							    mpcb->next_v6_index);
+				if (i < 0) {
+					mptcp_debug("%s: At max num of local addresses: %d --- not adding address: %pI6\n",
+						    __func__, MPTCP_MAX_ADDR,
+						    &ifa6->addr);
+					goto out;
+				}
+
+				mpcb->locaddr6[i].addr = ifa6->addr;
+				mpcb->locaddr6[i].port = 0;
+				mpcb->locaddr6[i].id = i + MPTCP_MAX_ADDR;
+				mpcb->locaddr6[i].low_prio = (dev->flags & IFF_MPBACKUP) ?
+								1 : 0;
+				mpcb->loc6_bits |= (1 << i);
+				mpcb->next_v6_index = i + 1;
+				mptcp_v6_send_add_addr(i, mpcb);
+			}
+#endif
+		}
+	}
+
+out:
+	read_unlock_bh(&dev_base_lock);
+	rcu_read_unlock();
+}
+
+int mptcp_check_req(struct sk_buff *skb, struct net *net)
+{
+	struct tcphdr *th = tcp_hdr(skb);
+	struct sock *meta_sk = NULL;
+
+	/* MPTCP structures not initialized */
+	if (mptcp_init_failed)
+		return 0;
+
+	if (skb->protocol == htons(ETH_P_IP))
+		meta_sk = mptcp_v4_search_req(th->source, ip_hdr(skb)->saddr,
+					      ip_hdr(skb)->daddr, net);
+#if IS_ENABLED(CONFIG_IPV6)
+	else /* IPv6 */
+		meta_sk = mptcp_v6_search_req(th->source, &ipv6_hdr(skb)->saddr,
+					      &ipv6_hdr(skb)->daddr, net);
+#endif /* CONFIG_IPV6 */
+
+	if (!meta_sk)
+		return 0;
+
+	TCP_SKB_CB(skb)->mptcp_flags = MPTCPHDR_JOIN;
+
+	bh_lock_sock_nested(meta_sk);
+	if (sock_owned_by_user(meta_sk)) {
+		skb->sk = meta_sk;
+		if (unlikely(sk_add_backlog(meta_sk, skb,
+					    meta_sk->sk_rcvbuf + meta_sk->sk_sndbuf))) {
+			bh_unlock_sock(meta_sk);
+			NET_INC_STATS_BH(net, LINUX_MIB_TCPBACKLOGDROP);
+			sock_put(meta_sk); /* Taken by mptcp_search_req */
+			kfree_skb(skb);
+			return 1;
+		}
+	} else if (skb->protocol == htons(ETH_P_IP)) {
+		tcp_v4_do_rcv(meta_sk, skb);
+#if IS_ENABLED(CONFIG_IPV6)
+	} else { /* IPv6 */
+		tcp_v6_do_rcv(meta_sk, skb);
+#endif /* CONFIG_IPV6 */
+	}
+	bh_unlock_sock(meta_sk);
+	sock_put(meta_sk); /* Taken by mptcp_vX_search_req */
+	return 1;
+}
+
+struct mp_join *mptcp_find_join(struct sk_buff *skb)
+{
+	struct tcphdr *th = tcp_hdr(skb);
+	unsigned char *ptr;
+	int length = (th->doff * 4) - sizeof(struct tcphdr);
+
+	/* Jump through the options to check whether JOIN is there */
+	ptr = (unsigned char *)(th + 1);
+	while (length > 0) {
+		int opcode = *ptr++;
+		int opsize;
+
+		switch (opcode) {
+		case TCPOPT_EOL:
+			return NULL;
+		case TCPOPT_NOP:	/* Ref: RFC 793 section 3.1 */
+			length--;
+			continue;
+		default:
+			opsize = *ptr++;
+			if (opsize < 2)	/* "silly options" */
+				return NULL;
+			if (opsize > length)
+				return NULL;  /* don't parse partial options */
+			if (opcode == TCPOPT_MPTCP &&
+			    ((struct mptcp_option *)(ptr - 2))->sub == MPTCP_SUB_JOIN) {
+				return (struct mp_join *)(ptr - 2);
+			}
+			ptr += opsize - 2;
+			length -= opsize;
+		}
+	}
+	return NULL;
+}
+
+int mptcp_lookup_join(struct sk_buff *skb, struct inet_timewait_sock *tw)
+{
+	struct mptcp_cb *mpcb;
+	struct sock *meta_sk;
+	u32 token;
+	struct mp_join *join_opt = mptcp_find_join(skb);
+	if (!join_opt)
+		return 0;
+
+	/* MPTCP structures were not initialized, so return error */
+	if (mptcp_init_failed)
+		return -1;
+
+	token = join_opt->u.syn.token;
+	meta_sk = mptcp_hash_find(dev_net(skb_dst(skb)->dev), token);
+	if (!meta_sk) {
+		mptcp_debug("%s:mpcb not found:%x\n", __func__, token);
+		return -1;
+	}
+
+	mpcb = tcp_sk(meta_sk)->mpcb;
+	if (mpcb->infinite_mapping_rcv || mpcb->send_infinite_mapping) {
+		/* We are in fallback-mode on the reception-side -
+		 * no new subflows!
+		 */
+		sock_put(meta_sk); /* Taken by mptcp_hash_find */
+		return -1;
+	}
+
+	/* Coming from time-wait-sock processing in tcp_v4_rcv.
+	 * We have to deschedule it before continuing, because otherwise
+	 * mptcp_v4_do_rcv will hit again on it inside tcp_v4_hnd_req.
+	 */
+	if (tw) {
+		inet_twsk_deschedule(tw, &tcp_death_row);
+		inet_twsk_put(tw);
+	}
+
+	TCP_SKB_CB(skb)->mptcp_flags = MPTCPHDR_JOIN;
+	/* OK, this is a new syn/join, let's create a new open request and
+	 * send syn+ack
+	 */
+	bh_lock_sock_nested(meta_sk);
+	if (sock_owned_by_user(meta_sk)) {
+		skb->sk = meta_sk;
+		if (unlikely(sk_add_backlog(meta_sk, skb,
+					    meta_sk->sk_rcvbuf + meta_sk->sk_sndbuf))) {
+			bh_unlock_sock(meta_sk);
+			NET_INC_STATS_BH(sock_net(meta_sk),
+					 LINUX_MIB_TCPBACKLOGDROP);
+			sock_put(meta_sk); /* Taken by mptcp_hash_find */
+			kfree_skb(skb);
+			return 1;
+		}
+	} else if (skb->protocol == htons(ETH_P_IP)) {
+		tcp_v4_do_rcv(meta_sk, skb);
+#if IS_ENABLED(CONFIG_IPV6)
+	} else {
+		tcp_v6_do_rcv(meta_sk, skb);
+#endif /* CONFIG_IPV6 */
+	}
+	bh_unlock_sock(meta_sk);
+	sock_put(meta_sk); /* Taken by mptcp_hash_find */
+	return 1;
+}
+
+int mptcp_do_join_short(struct sk_buff *skb, struct mptcp_options_received *mopt,
+			struct tcp_options_received *tmp_opt, struct net *net)
+{
+	struct sock *meta_sk;
+	u32 token;
+
+	token = mopt->mptcp_rem_token;
+	meta_sk = mptcp_hash_find(net, token);
+	if (!meta_sk) {
+		mptcp_debug("%s:mpcb not found:%x\n", __func__, token);
+		return -1;
+	}
+
+	TCP_SKB_CB(skb)->mptcp_flags = MPTCPHDR_JOIN;
+
+	/* OK, this is a new syn/join, let's create a new open request and
+	 * send syn+ack
+	 */
+	bh_lock_sock(meta_sk);
+
+	/* This check is also done in mptcp_vX_do_rcv. But, there we cannot
+	 * call tcp_vX_send_reset, because we hold already two socket-locks.
+	 * (the listener and the meta from above)
+	 *
+	 * And the send-reset will try to take yet another one (ip_send_reply).
+	 * Thus, we propagate the reset up to tcp_rcv_state_process.
+	 */
+	if (tcp_sk(meta_sk)->mpcb->infinite_mapping_rcv ||
+	    tcp_sk(meta_sk)->mpcb->send_infinite_mapping ||
+	    meta_sk->sk_state == TCP_CLOSE || !tcp_sk(meta_sk)->inside_tk_table) {
+		bh_unlock_sock(meta_sk);
+		sock_put(meta_sk); /* Taken by mptcp_hash_find */
+		return -1;
+	}
+
+	if (sock_owned_by_user(meta_sk)) {
+		skb->sk = meta_sk;
+		if (unlikely(sk_add_backlog(meta_sk, skb,
+					    meta_sk->sk_rcvbuf + meta_sk->sk_sndbuf)))
+			NET_INC_STATS_BH(net, LINUX_MIB_TCPBACKLOGDROP);
+		else
+			/* Must make sure that upper layers won't free the
+			 * skb if it is added to the backlog-queue.
+			 */
+			skb_get(skb);
+	} else {
+		/* mptcp_v4_do_rcv tries to free the skb - we prevent this, as
+		 * the skb will finally be freed by tcp_v4_do_rcv (where we are
+		 * coming from)
+		 */
+		skb_get(skb);
+		if (skb->protocol == htons(ETH_P_IP)) {
+			tcp_v4_do_rcv(meta_sk, skb);
+#if IS_ENABLED(CONFIG_IPV6)
+		} else { /* IPv6 */
+			tcp_v6_do_rcv(meta_sk, skb);
+#endif /* CONFIG_IPV6 */
+		}
+	}
+
+	bh_unlock_sock(meta_sk);
+	sock_put(meta_sk); /* Taken by mptcp_hash_find */
+	return 0;
+}
+
+void mptcp_retry_subflow_worker(struct work_struct *work)
+{
+	struct delayed_work *delayed_work =
+		container_of(work, struct delayed_work, work);
+	struct mptcp_cb *mpcb =
+		container_of(delayed_work, struct mptcp_cb, subflow_retry_work);
+	struct sock *meta_sk = mpcb->meta_sk;
+	int iter = 0, i;
+
+next_subflow:
+	if (iter) {
+		release_sock(meta_sk);
+		mutex_unlock(&mpcb->mutex);
+
+		yield();
+	}
+	mutex_lock(&mpcb->mutex);
+	lock_sock_nested(meta_sk, SINGLE_DEPTH_NESTING);
+
+	iter++;
+
+	if (sock_flag(meta_sk, SOCK_DEAD))
+		goto exit;
+
+	mptcp_for_each_bit_set(mpcb->rem4_bits, i) {
+		struct mptcp_rem4 *rem = &mpcb->remaddr4[i];
+		/* Do we need to retry establishing a subflow ? */
+		if (rem->retry_bitfield) {
+			int i = mptcp_find_free_index(~rem->retry_bitfield);
+			mptcp_init4_subsockets(meta_sk, &mpcb->locaddr4[i], rem);
+			rem->retry_bitfield &= ~(1 << mpcb->locaddr4[i].id);
+			goto next_subflow;
+		}
+	}
+
+#if IS_ENABLED(CONFIG_IPV6)
+	mptcp_for_each_bit_set(mpcb->rem6_bits, i) {
+		struct mptcp_rem6 *rem = &mpcb->remaddr6[i];
+
+		/* Do we need to retry establishing a subflow ? */
+		if (rem->retry_bitfield) {
+			int i = mptcp_find_free_index(~rem->retry_bitfield);
+			mptcp_init6_subsockets(meta_sk, &mpcb->locaddr6[i], rem);
+			rem->retry_bitfield &= ~(1 << mpcb->locaddr6[i].id);
+			goto next_subflow;
+		}
+	}
+#endif
+
+exit:
+	release_sock(meta_sk);
+	mutex_unlock(&mpcb->mutex);
+	sock_put(meta_sk);
+}
+
+/**
+ * Create all new subflows, by doing calls to mptcp_initX_subsockets
+ *
+ * This function uses a goto next_subflow, to allow releasing the lock between
+ * new subflows and giving other processes a chance to do some work on the
+ * socket and potentially finishing the communication.
+ **/
+void mptcp_create_subflow_worker(struct work_struct *work)
+{
+	struct mptcp_cb *mpcb = container_of(work, struct mptcp_cb, subflow_work);
+	struct sock *meta_sk = mpcb->meta_sk;
+	int iter = 0, retry = 0;
+	int i;
+
+next_subflow:
+	if (iter) {
+		release_sock(meta_sk);
+		mutex_unlock(&mpcb->mutex);
+
+		yield();
+	}
+	mutex_lock(&mpcb->mutex);
+	lock_sock_nested(meta_sk, SINGLE_DEPTH_NESTING);
+
+	iter++;
+
+	if (sock_flag(meta_sk, SOCK_DEAD))
+		goto exit;
+
+	if (sysctl_mptcp_ndiffports > iter &&
+	    sysctl_mptcp_ndiffports > mpcb->cnt_subflows) {
+		if (meta_sk->sk_family == AF_INET ||
+		    mptcp_v6_is_v4_mapped(meta_sk)) {
+			mptcp_init4_subsockets(meta_sk, &mpcb->locaddr4[0],
+					       &mpcb->remaddr4[0]);
+		} else {
+#if IS_ENABLED(CONFIG_IPV6)
+			mptcp_init6_subsockets(meta_sk, &mpcb->locaddr6[0],
+					       &mpcb->remaddr6[0]);
+#endif
+		}
+		goto next_subflow;
+	}
+	if (sysctl_mptcp_ndiffports > 1 &&
+	    sysctl_mptcp_ndiffports == mpcb->cnt_subflows)
+		goto exit;
+
+	mptcp_for_each_bit_set(mpcb->rem4_bits, i) {
+		struct mptcp_rem4 *rem;
+		u8 remaining_bits;
+
+		rem = &mpcb->remaddr4[i];
+		remaining_bits = ~(rem->bitfield) & mpcb->loc4_bits;
+
+		/* Are there still combinations to handle? */
+		if (remaining_bits) {
+			int i = mptcp_find_free_index(~remaining_bits);
+			/* If a route is not yet available then retry once */
+			if (mptcp_init4_subsockets(meta_sk, &mpcb->locaddr4[i],
+						   rem) == -ENETUNREACH)
+				retry = rem->retry_bitfield |=
+					(1 << mpcb->locaddr4[i].id);
+			goto next_subflow;
+		}
+	}
+
+#if IS_ENABLED(CONFIG_IPV6)
+	mptcp_for_each_bit_set(mpcb->rem6_bits, i) {
+		struct mptcp_rem6 *rem;
+		u8 remaining_bits;
+
+		rem = &mpcb->remaddr6[i];
+		remaining_bits = ~(rem->bitfield) & mpcb->loc6_bits;
+
+		/* Are there still combinations to handle? */
+		if (remaining_bits) {
+			int i = mptcp_find_free_index(~remaining_bits);
+			/* If a route is not yet available then retry once */
+			if (mptcp_init6_subsockets(meta_sk, &mpcb->locaddr6[i],
+						   rem) == -ENETUNREACH)
+				retry = rem->retry_bitfield |=
+					(1 << mpcb->locaddr6[i].id);
+			goto next_subflow;
+		}
+	}
+#endif
+
+	if (retry && !delayed_work_pending(&mpcb->subflow_retry_work)) {
+		sock_hold(meta_sk);
+		queue_delayed_work(mptcp_wq, &mpcb->subflow_retry_work,
+				   msecs_to_jiffies(MPTCP_SUBFLOW_RETRY_DELAY));
+	}
+
+exit:
+	release_sock(meta_sk);
+	mutex_unlock(&mpcb->mutex);
+	sock_put(meta_sk);
+}
+
+void mptcp_create_subflows(struct sock *meta_sk)
+{
+	struct mptcp_cb *mpcb = tcp_sk(meta_sk)->mpcb;
+
+	if ((mpcb->master_sk &&
+	     !tcp_sk(mpcb->master_sk)->mptcp->fully_established) ||
+	    mpcb->infinite_mapping_snd || mpcb->infinite_mapping_rcv ||
+	    mpcb->send_infinite_mapping ||
+	    mpcb->server_side || sock_flag(meta_sk, SOCK_DEAD))
+		return;
+
+	if (!work_pending(&mpcb->subflow_work)) {
+		sock_hold(meta_sk);
+		queue_work(mptcp_wq, &mpcb->subflow_work);
+	}
+}
+
+void mptcp_address_worker(struct work_struct *work)
+{
+	struct mptcp_cb *mpcb = container_of(work, struct mptcp_cb, address_work);
+	struct sock *meta_sk = mpcb->meta_sk, *sk, *tmpsk;
+	struct net *netns = sock_net(meta_sk);
+	struct net_device *dev;
+	int i;
+
+	mutex_lock(&mpcb->mutex);
+	lock_sock(meta_sk);
+
+	if (sock_flag(meta_sk, SOCK_DEAD))
+		goto exit;
+
+	/* The following is meant to run with bh disabled */
+	local_bh_disable();
+
+	/* First, we iterate over the interfaces to find addresses not yet
+	 * in our local list.
+	 */
+
+	rcu_read_lock();
+	read_lock_bh(&dev_base_lock);
+
+	for_each_netdev(netns, dev) {
+		struct in_device *in_dev = __in_dev_get_rcu(dev);
+		struct in_ifaddr *ifa;
+#if IS_ENABLED(CONFIG_IPV6)
+		struct inet6_dev *in6_dev = __in6_dev_get(dev);
+		struct inet6_ifaddr *ifa6;
+#endif
+
+		if (dev->flags & (IFF_LOOPBACK | IFF_NOMULTIPATH))
+			continue;
+
+		if (!in_dev)
+			goto cont_ipv6;
+
+		for (ifa = in_dev->ifa_list; ifa; ifa = ifa->ifa_next) {
+			unsigned long event;
+
+			if (!netif_running(in_dev->dev)) {
+				event = NETDEV_DOWN;
+			} else {
+				/* If it's up, it may have been changed or came up.
+				 * We set NETDEV_CHANGE, to take the good
+				 * code-path in mptcp_pm_addr4_event_handler
+				 */
+				event = NETDEV_CHANGE;
+			}
+
+			mptcp_pm_addr4_event_handler(ifa, event, mpcb);
+		}
+cont_ipv6:
+; /* This ; is necessary to fix build-errors when IPv6 is disabled */
+#if IS_ENABLED(CONFIG_IPV6)
+		if (!in6_dev)
+			continue;
+
+		read_lock(&in6_dev->lock);
+		list_for_each_entry(ifa6, &in6_dev->addr_list, if_list) {
+			unsigned long event;
+
+			if (!netif_running(in_dev->dev)) {
+				event = NETDEV_DOWN;
+			} else {
+				/* If it's up, it may have been changed or came up.
+				 * We set NETDEV_CHANGE, to take the good
+				 * code-path in mptcp_pm_addr4_event_handler
+				 */
+				event = NETDEV_CHANGE;
+			}
+
+			mptcp_pm_addr6_event_handler(ifa6, event, mpcb);
+		}
+		read_unlock(&in6_dev->lock);
+#endif
+	}
+
+	/* Second, we iterate over our local addresses and check if they
+	 * still exist in the interface-list.
+	 */
+
+	/* MPCB-Local IPv4 Addresses */
+	mptcp_for_each_bit_set(mpcb->loc4_bits, i) {
+		int j;
+
+		for_each_netdev(netns, dev) {
+			struct in_device *in_dev = __in_dev_get_rcu(dev);
+			struct in_ifaddr *ifa;
+
+			if (dev->flags & (IFF_LOOPBACK | IFF_NOMULTIPATH) ||
+			    !in_dev)
+				continue;
+
+			for (ifa = in_dev->ifa_list; ifa; ifa = ifa->ifa_next) {
+				if (ifa->ifa_address == mpcb->locaddr4[i].addr.s_addr &&
+				    netif_running(dev))
+					goto next_loc_addr;
+			}
+		}
+
+		/* We did not find the address or the interface became NOMULTIPATH.
+		 * We thus have to remove it.
+		 */
+
+		/* Look for the socket and remove him */
+		mptcp_for_each_sk_safe(mpcb, sk, tmpsk) {
+			if (sk->sk_family != AF_INET ||
+			    inet_sk(sk)->inet_saddr != mpcb->locaddr4[i].addr.s_addr)
+				continue;
+
+			mptcp_reinject_data(sk, 0);
+			mptcp_sub_force_close(sk);
+		}
+
+		/* Now, remove the address from the local ones */
+		mpcb->loc4_bits &= ~(1 << i);
+
+		mpcb->remove_addrs |= (1 << mpcb->locaddr4[i].id);
+		sk = mptcp_select_ack_sock(meta_sk, 0);
+		if (sk)
+			tcp_send_ack(sk);
+
+		mptcp_for_each_bit_set(mpcb->rem4_bits, j)
+			mpcb->remaddr4[j].bitfield &= mpcb->loc4_bits;
+
+next_loc_addr:
+		continue; /* necessary here due to the previous label */
+	}
+
+#if IS_ENABLED(CONFIG_IPV6)
+	/* MPCB-Local IPv6 Addresses */
+	mptcp_for_each_bit_set(mpcb->loc6_bits, i) {
+		int j;
+
+		for_each_netdev(netns, dev) {
+			struct inet6_dev *in6_dev = __in6_dev_get(dev);
+			struct inet6_ifaddr *ifa6;
+
+			if (dev->flags & (IFF_LOOPBACK | IFF_NOMULTIPATH) ||
+			    !in6_dev)
+				continue;
+
+			read_lock(&in6_dev->lock);
+			list_for_each_entry(ifa6, &in6_dev->addr_list, if_list) {
+				if (ipv6_addr_equal(&mpcb->locaddr6[i].addr, &ifa6->addr) &&
+				    netif_running(dev)) {
+					read_unlock(&in6_dev->lock);
+					goto next_loc6_addr;
+				}
+			}
+			read_unlock(&in6_dev->lock);
+		}
+
+		/* We did not find the address or the interface became NOMULTIPATH.
+		 * We thus have to remove it.
+		 */
+
+		/* Look for the socket and remove him */
+		mptcp_for_each_sk_safe(mpcb, sk, tmpsk) {
+			if (sk->sk_family != AF_INET6 ||
+			    !ipv6_addr_equal(&inet6_sk(sk)->saddr, &mpcb->locaddr6[i].addr))
+				continue;
+
+			mptcp_reinject_data(sk, 0);
+			mptcp_sub_force_close(sk);
+		}
+
+		/* Now, remove the address from the local ones */
+		mpcb->loc6_bits &= ~(1 << i);
+
+		/* Force sending directly the REMOVE_ADDR option */
+		mpcb->remove_addrs |= (1 << mpcb->locaddr6[i].id);
+		sk = mptcp_select_ack_sock(meta_sk, 0);
+		if (sk)
+			tcp_send_ack(sk);
+
+		mptcp_for_each_bit_set(mpcb->rem6_bits, j)
+			mpcb->remaddr6[j].bitfield &= mpcb->loc6_bits;
+
+next_loc6_addr:
+		continue; /* necessary here due to the previous label */
+	}
+#endif
+
+	read_unlock_bh(&dev_base_lock);
+	rcu_read_unlock();
+
+	local_bh_enable();
+exit:
+	release_sock(meta_sk);
+	mutex_unlock(&mpcb->mutex);
+	sock_put(meta_sk);
+}
+
+static void mptcp_address_create_worker(struct mptcp_cb *mpcb)
+{
+	if (!work_pending(&mpcb->address_work)) {
+		sock_hold(mpcb->meta_sk);
+		queue_work(mptcp_wq, &mpcb->address_work);
+	}
+}
+
+/**
+ * React on IPv4+IPv6-addr add/rem-events
+ */
+int mptcp_pm_addr_event_handler(unsigned long event, void *ptr, int family)
+{
+	struct tcp_sock *meta_tp;
+	int i;
+
+	if (!(event == NETDEV_UP || event == NETDEV_DOWN ||
+	      event == NETDEV_CHANGE))
+		return NOTIFY_DONE;
+
+	if (sysctl_mptcp_ndiffports > 1)
+		return NOTIFY_DONE;
+
+	/* Now we iterate over the mpcb's */
+	for (i = 0; i < MPTCP_HASH_SIZE; i++) {
+		struct hlist_nulls_node *node;
+		rcu_read_lock_bh();
+		hlist_nulls_for_each_entry_rcu(meta_tp, node, &tk_hashtable[i],
+					       tk_table) {
+			struct mptcp_cb *mpcb = meta_tp->mpcb;
+			struct sock *meta_sk = (struct sock *)meta_tp;
+
+			if (unlikely(!atomic_inc_not_zero(&meta_sk->sk_refcnt)))
+				continue;
+
+			if (!meta_tp->mpc || !is_meta_sk(meta_sk) ||
+			    mpcb->infinite_mapping_snd ||
+			    mpcb->infinite_mapping_rcv ||
+			    mpcb->send_infinite_mapping) {
+				sock_put(meta_sk);
+				continue;
+			}
+
+			bh_lock_sock(meta_sk);
+			if (sock_owned_by_user(meta_sk)) {
+				mptcp_address_create_worker(mpcb);
+			} else {
+				if (family == AF_INET)
+					mptcp_pm_addr4_event_handler(
+							(struct in_ifaddr *)ptr, event, mpcb);
+#if IS_ENABLED(CONFIG_IPV6)
+				else
+					mptcp_pm_addr6_event_handler(
+							(struct inet6_ifaddr *)ptr, event, mpcb);
+#endif
+			}
+
+			bh_unlock_sock(meta_sk);
+			sock_put(meta_sk);
+		}
+		rcu_read_unlock_bh();
+	}
+	return NOTIFY_DONE;
+}
+
+#ifdef CONFIG_PROC_FS
+
+/* Output /proc/net/mptcp */
+static int mptcp_pm_seq_show(struct seq_file *seq, void *v)
+{
+	struct tcp_sock *meta_tp;
+	struct net *net = seq->private;
+	int i, n = 0;
+
+	seq_printf(seq, "  sl  loc_tok  rem_tok  v6 "
+		   "local_address                         "
+		   "remote_address                        "
+		   "st ns tx_queue rx_queue inode");
+	seq_putc(seq, '\n');
+
+	for (i = 0; i < MPTCP_HASH_SIZE; i++) {
+		struct hlist_nulls_node *node;
+		rcu_read_lock_bh();
+		hlist_nulls_for_each_entry_rcu(meta_tp, node,
+					       &tk_hashtable[i], tk_table) {
+			struct mptcp_cb *mpcb = meta_tp->mpcb;
+			struct sock *meta_sk = (struct sock *)meta_tp;
+			struct inet_sock *isk = inet_sk(meta_sk);
+
+			if (!meta_tp->mpc || !net_eq(net, sock_net(meta_sk)))
+				continue;
+
+			seq_printf(seq, "%4d: %04X %04X ", n++,
+				   mpcb->mptcp_loc_token,
+				   mpcb->mptcp_rem_token);
+			if (meta_sk->sk_family == AF_INET ||
+			    mptcp_v6_is_v4_mapped(meta_sk)) {
+				seq_printf(seq, " 0 %08X:%04X                         %08X:%04X                        ",
+					   isk->inet_saddr,
+					   ntohs(isk->inet_sport),
+					   isk->inet_daddr,
+					   ntohs(isk->inet_dport));
+#if IS_ENABLED(CONFIG_IPV6)
+			} else if (meta_sk->sk_family == AF_INET6) {
+				struct in6_addr *src = &isk->pinet6->saddr;
+				struct in6_addr *dst = &isk->pinet6->daddr;
+				seq_printf(seq, " 1 %08X%08X%08X%08X:%04X %08X%08X%08X%08X:%04X",
+					   src->s6_addr32[0], src->s6_addr32[1],
+					   src->s6_addr32[2], src->s6_addr32[3],
+					   ntohs(isk->inet_sport),
+					   dst->s6_addr32[0], dst->s6_addr32[1],
+					   dst->s6_addr32[2], dst->s6_addr32[3],
+					   ntohs(isk->inet_dport));
+#endif
+			}
+			seq_printf(seq, " %02X %02X %08X:%08X %lu",
+				   meta_sk->sk_state, mpcb->cnt_subflows,
+				   meta_tp->write_seq - meta_tp->snd_una,
+				   max_t(int, meta_tp->rcv_nxt -
+					 meta_tp->copied_seq, 0),
+				   sock_i_ino(meta_sk));
+			seq_putc(seq, '\n');
+		}
+		rcu_read_unlock_bh();
+	}
+
+	return 0;
+}
+
+static int mptcp_pm_seq_open(struct inode *inode, struct file *file)
+{
+	return single_open_net(inode, file, mptcp_pm_seq_show);
+}
+
+static const struct file_operations mptcp_pm_seq_fops = {
+	.owner = THIS_MODULE,
+	.open = mptcp_pm_seq_open,
+	.read = seq_read,
+	.llseek = seq_lseek,
+	.release = single_release_net,
+};
+
+static int mptcp_pm_proc_init_net(struct net *net)
+{
+	if (!proc_create("mptcp", S_IRUGO, net->proc_net, &mptcp_pm_seq_fops))
+		return -ENOMEM;
+
+	return 0;
+}
+
+static void mptcp_pm_proc_exit_net(struct net *net)
+{
+	remove_proc_entry("mptcp", net->proc_net);
+}
+
+static struct pernet_operations mptcp_pm_proc_ops = {
+	.init = mptcp_pm_proc_init_net,
+	.exit = mptcp_pm_proc_exit_net,
+};
+#endif
+
+/* General initialization of MPTCP_PM */
+int mptcp_pm_init(void)
+{
+	int i, ret;
+	for (i = 0; i < MPTCP_HASH_SIZE; i++) {
+		INIT_HLIST_NULLS_HEAD(&tk_hashtable[i], i);
+		INIT_LIST_HEAD(&mptcp_reqsk_htb[i]);
+		INIT_HLIST_NULLS_HEAD(&mptcp_reqsk_tk_htb[i], i);
+	}
+
+	spin_lock_init(&mptcp_reqsk_hlock);
+	spin_lock_init(&mptcp_tk_hashlock);
+
+#ifdef CONFIG_PROC_FS
+	ret = register_pernet_subsys(&mptcp_pm_proc_ops);
+	if (ret)
+		goto out;
+#endif
+
+#if IS_ENABLED(CONFIG_IPV6)
+	ret = mptcp_pm_v6_init();
+	if (ret)
+		goto mptcp_pm_v6_failed;
+#endif
+	ret = mptcp_pm_v4_init();
+	if (ret)
+		goto mptcp_pm_v4_failed;
+
+out:
+	return ret;
+
+mptcp_pm_v4_failed:
+#if IS_ENABLED(CONFIG_IPV6)
+	mptcp_pm_v6_undo();
+
+mptcp_pm_v6_failed:
+#endif
+#ifdef CONFIG_PROC_FS
+	unregister_pernet_subsys(&mptcp_pm_proc_ops);
+#endif
+	goto out;
+}
+
+void mptcp_pm_undo(void)
+{
+#if IS_ENABLED(CONFIG_IPV6)
+	mptcp_pm_v6_undo();
+#endif
+	mptcp_pm_v4_undo();
+#ifdef CONFIG_PROC_FS
+	unregister_pernet_subsys(&mptcp_pm_proc_ops);
+#endif
+}