[patch] Patch against 6.1-RELEASE fixing the deadlock (but racing at unmount time)

kernel-fix-devfs-deadlock.patch (text/plain), 4.49 KB, created by Alex Unleashed on 2006-09-04 09:37:09 UTC

diff -Naur devfs/devfs.h devfsb/devfs.h
--- devfs/devfs.h	2006-08-18 17:23:00 +0000
+++ devfsb/devfs.h	2006-09-03 19:34:57 +0000
@@ -163,7 +163,7 @@
 void devfs_rules_apply(struct devfs_mount *dm, struct devfs_dirent *de);
 void devfs_rules_cleanup (struct devfs_mount *dm);
 int devfs_rules_ioctl(struct devfs_mount *dm, u_long cmd, caddr_t data, struct thread *td);
-int devfs_allocv (struct devfs_dirent *de, struct mount *mp, struct vnode **vpp, struct thread *td);
+int devfs_allocv (struct devfs_dirent *de, struct mount *mp, struct vnode **vpp, int *dm_unlock, struct thread *td);
 struct cdev **devfs_itod (int inode);
 struct devfs_dirent **devfs_itode (struct devfs_mount *dm, int inode);
 void devfs_delete(struct devfs_mount *dm, struct devfs_dirent *de);
diff -Naur devfs/devfs_vfsops.c devfsb/devfs_vfsops.c
--- devfs/devfs_vfsops.c	2006-08-18 17:23:00 +0000
+++ devfsb/devfs_vfsops.c	2006-09-03 19:34:57 +0000
@@ -139,9 +139,11 @@
 	int error;
 	struct vnode *vp;
 	struct devfs_mount *dmp;
+	int dm_unlock;
 
 	dmp = VFSTODEVFS(mp);
-	error = devfs_allocv(dmp->dm_rootdir, mp, &vp, td);
+	dm_unlock = 0;
+	error = devfs_allocv(dmp->dm_rootdir, mp, &vp, &dm_unlock, td);
 	if (error)
 		return (error);
 	vp->v_vflag |= VV_ROOT;
diff -Naur devfs/devfs_vnops.c devfsb/devfs_vnops.c
--- devfs/devfs_vnops.c	2006-08-18 17:23:00 +0000
+++ devfsb/devfs_vnops.c	2006-09-03 19:34:57 +0000
@@ -124,16 +124,23 @@
 }
 
 int
-devfs_allocv(struct devfs_dirent *de, struct mount *mp, struct vnode **vpp, struct thread *td)
+devfs_allocv(struct devfs_dirent *de, struct mount *mp, struct vnode **vpp,
+	int *dm_unlock, struct thread *td)
 {
 	int error;
 	struct vnode *vp;
 	struct cdev *dev;
+	struct devfs_mount *dmp;
 
 	KASSERT(td == curthread, ("devfs_allocv: td != curthread"));
+	dmp = VFSTODEVFS(mp);
 loop:
 	vp = de->de_vnode;
 	if (vp != NULL) {
+		if (*dm_unlock) {
+			sx_xunlock(&dmp->dm_lock);
+			*dm_unlock = 0;
+		}
 		if (vget(vp, LK_EXCLUSIVE, td))
 			goto loop;
 		*vpp = vp;
@@ -173,6 +180,10 @@
 	}
 	vp->v_data = de;
 	de->de_vnode = vp;
+	if (*dm_unlock) {
+		sx_xunlock(&dmp->dm_lock);
+		*dm_unlock = 0;
+	}
 	vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td);
 #ifdef MAC
 	mac_associate_vnode_devfs(mp, de, vp);
@@ -453,7 +464,7 @@
 }
 
 static int
-devfs_lookupx(struct vop_lookup_args *ap)
+devfs_lookupx(struct vop_lookup_args *ap, int *dm_unlock)
 {
 	struct componentname *cnp;
 	struct vnode *dvp, **vpp;
@@ -504,7 +515,7 @@
 		de = TAILQ_FIRST(&dd->de_dlist);	/* "." */
 		de = TAILQ_NEXT(de, de_list);		/* ".." */
 		de = de->de_dir;
-		error = devfs_allocv(de, dvp->v_mount, vpp, td);
+		error = devfs_allocv(de, dvp->v_mount, vpp, dm_unlock, td);
 		vn_lock(dvp, LK_EXCLUSIVE | LK_RETRY, td);
 		return (error);
 	}
@@ -561,7 +572,7 @@
 			return (0);
 		}
 	}
-	error = devfs_allocv(de, dvp->v_mount, vpp, td);
+	error = devfs_allocv(de, dvp->v_mount, vpp, dm_unlock, td);
 	return (error);
 }
 
@@ -570,11 +581,14 @@
 {
 	int j;
 	struct devfs_mount *dmp;
+	int dm_unlock;
 
 	dmp = VFSTODEVFS(ap->a_dvp->v_mount);
+	dm_unlock = 1;
 	sx_xlock(&dmp->dm_lock);
-	j = devfs_lookupx(ap);
-	sx_xunlock(&dmp->dm_lock);
+	j = devfs_lookupx(ap, &dm_unlock);
+	if (dm_unlock == 1)
+		sx_xunlock(&dmp->dm_lock);
 	return (j);
 }
 
@@ -586,6 +600,7 @@
 	struct thread *td;
 	struct devfs_dirent *dd, *de;
 	struct devfs_mount *dmp;
+	int dm_unlock;
 	int error;
 
 	/*
@@ -597,6 +612,7 @@
 	dvp = ap->a_dvp;
 	dmp = VFSTODEVFS(dvp->v_mount);
 	sx_xlock(&dmp->dm_lock);
+	dm_unlock = 1;
 
 	cnp = ap->a_cnp;
 	vpp = ap->a_vpp;
@@ -617,9 +633,10 @@
 	if (de == NULL)
 		goto notfound;
 	de->de_flags &= ~DE_WHITEOUT;
-	error = devfs_allocv(de, dvp->v_mount, vpp, td);
+	error = devfs_allocv(de, dvp->v_mount, vpp, &dm_unlock, td);
 notfound:
-	sx_xunlock(&dmp->dm_lock);
+	if (dm_unlock == 1)
+		sx_xunlock(&dmp->dm_lock);
 	return (error);
 }
 
@@ -1101,6 +1118,7 @@
 	struct devfs_dirent *de;
 	struct devfs_mount *dmp;
 	struct thread *td;
+	int dm_unlock;
 
 	td = ap->a_cnp->cn_thread;
 	KASSERT(td == curthread, ("devfs_symlink: td != curthread"));
@@ -1119,12 +1137,14 @@
 	de->de_symlink = malloc(i, M_DEVFS, M_WAITOK);
 	bcopy(ap->a_target, de->de_symlink, i);
 	sx_xlock(&dmp->dm_lock);
+	dm_unlock = 1;
 #ifdef MAC
 	mac_create_devfs_symlink(ap->a_cnp->cn_cred, dmp->dm_mount, dd, de);
 #endif
 	TAILQ_INSERT_TAIL(&dd->de_dlist, de, de_list);
-	devfs_allocv(de, ap->a_dvp->v_mount, ap->a_vpp, td);
-	sx_xunlock(&dmp->dm_lock);
+	devfs_allocv(de, ap->a_dvp->v_mount, ap->a_vpp, &dm_unlock, td);
+	if (dm_unlock == 1)
+		sx_xunlock(&dmp->dm_lock);
 	return (0);
 }