Make VirtualBox-4.1.16 kernel modules work again on kernels 3.5rc0+
(after Al Viro removed do_mmap()/do_munmap() from public view).

Manuel Lauss, 20120603

diff -Naurp vboxdrv.old/r0drv/linux/memobj-r0drv-linux.c vboxdrv/r0drv/linux/memobj-r0drv-linux.c
--- vboxdrv.old/r0drv/linux/memobj-r0drv-linux.c	2012-01-19 13:37:00.000000000 +0100
+++ vboxdrv/r0drv/linux/memobj-r0drv-linux.c	2012-06-03 09:17:16.417650091 +0200
@@ -491,9 +491,7 @@ DECLHIDDEN(int) rtR0MemObjNativeFree(RTR
                 Assert(pTask);
                 if (pTask && pTask->mm)
                 {
-                    down_write(&pTask->mm->mmap_sem);
                     MY_DO_MUNMAP(pTask->mm, (unsigned long)pMemLnx->Core.pv, pMemLnx->Core.cb);
-                    up_write(&pTask->mm->mmap_sem);
                 }
             }
             else
@@ -516,9 +514,7 @@ DECLHIDDEN(int) rtR0MemObjNativeFree(RTR
                 Assert(pTask);
                 if (pTask && pTask->mm)
                 {
-                    down_write(&pTask->mm->mmap_sem);
                     MY_DO_MUNMAP(pTask->mm, (unsigned long)pMemLnx->Core.pv, pMemLnx->Core.cb);
-                    up_write(&pTask->mm->mmap_sem);
                 }
             }
             else
@@ -1147,10 +1143,10 @@ static void *rtR0MemObjLinuxDoMmap(RTR3P
     }
 
     if (R3PtrFixed != (RTR3PTR)-1)
-        ulAddr = do_mmap(NULL, R3PtrFixed, cb, fLnxProt, MAP_SHARED | MAP_ANONYMOUS | MAP_FIXED, 0);
+        ulAddr = MY_DO_MMAP(NULL, R3PtrFixed, cb, fLnxProt, MAP_SHARED | MAP_ANONYMOUS | MAP_FIXED, 0);
     else
     {
-        ulAddr = do_mmap(NULL, 0, cb, fLnxProt, MAP_SHARED | MAP_ANONYMOUS, 0);
+        ulAddr = MY_DO_MMAP(NULL, 0, cb, fLnxProt, MAP_SHARED | MAP_ANONYMOUS, 0);
         if (    !(ulAddr & ~PAGE_MASK)
             &&  (ulAddr & (uAlignment - 1)))
         {
@@ -1192,9 +1188,7 @@ DECLHIDDEN(int) rtR0MemObjNativeReserveU
     pMemLnx = (PRTR0MEMOBJLNX)rtR0MemObjNew(sizeof(*pMemLnx), RTR0MEMOBJTYPE_RES_VIRT, pv, cb);
     if (!pMemLnx)
     {
-        down_write(&pTask->mm->mmap_sem);
         MY_DO_MUNMAP(pTask->mm, (unsigned long)pv, cb);
-        up_write(&pTask->mm->mmap_sem);
         return VERR_NO_MEMORY;
     }
 
@@ -1381,7 +1375,9 @@ DECLHIDDEN(int) rtR0MemObjNativeMapUser(
          * Allocate user space mapping.
          */
         void *pv;
+#ifndef LINUX_NO_DOMMAP
         down_write(&pTask->mm->mmap_sem);
+#endif
         pv = rtR0MemObjLinuxDoMmap(R3PtrFixed, pMemLnxToMap->Core.cb, uAlignment, pTask, fProt);
         if (pv != (void *)-1)
         {
@@ -1394,6 +1390,9 @@ DECLHIDDEN(int) rtR0MemObjNativeMapUser(
             const size_t    cPages = pMemLnxToMap->Core.cb >> PAGE_SHIFT;
             size_t          iPage;
 
+#ifdef LINUX_NO_DOMMAP
+	    down_write(&pTask->mm->mmap_sem);
+#endif
             rc = 0;
             if (pMemLnxToMap->cPages)
             {
@@ -1428,6 +1427,9 @@ DECLHIDDEN(int) rtR0MemObjNativeMapUser(
                     if (rc)
                     {
                         rc = VERR_NO_MEMORY;
+#ifdef LINUX_NO_DOMMAP
+			up_write(&pTask->mm->mmap_sem);
+#endif
                         break;
                     }
                 }
@@ -1471,6 +1473,9 @@ DECLHIDDEN(int) rtR0MemObjNativeMapUser(
                         if (rc)
                         {
                             rc = VERR_NO_MEMORY;
+#ifdef LINUX_NO_DOMMAP
+                            up_write(&pTask->mm->mmap_sem);
+#endif
                             break;
                         }
                     }
@@ -1489,14 +1494,20 @@ DECLHIDDEN(int) rtR0MemObjNativeMapUser(
                 return VINF_SUCCESS;
             }
 
+            up_write(&pTask->mm->mmap_sem);
             /*
              * Bail out.
              */
             MY_DO_MUNMAP(pTask->mm, (unsigned long)pv, pMemLnxToMap->Core.cb);
+#ifndef LINUX_NO_DOMMAP
+            down_write(&pTask->mm->mmap_sem);
+#endif
         }
-        up_write(&pTask->mm->mmap_sem);
         rtR0MemObjDelete(&pMemLnx->Core);
     }
+#ifndef LINUX_NO_DOMMAP
+    up_write(&pTask->mm->mmap_sem);
+#endif
 #ifdef VBOX_USE_PAE_HACK
     __free_page(pDummyPage);
 #endif
diff -Naurp vboxdrv.old/r0drv/linux/the-linux-kernel.h vboxdrv/r0drv/linux/the-linux-kernel.h
--- vboxdrv.old/r0drv/linux/the-linux-kernel.h	2012-01-31 15:17:37.000000000 +0100
+++ vboxdrv/r0drv/linux/the-linux-kernel.h	2012-06-03 09:20:33.996406929 +0200
@@ -269,6 +269,24 @@ DECLINLINE(unsigned long) msecs_to_jiffi
 # endif  /* !RT_ARCH_AMD64 */
 #endif /* !NO_REDHAT_HACKS */
 
+/* 3.5rc0 gets rid of do_mmap() and do_munmap().
+ * need to change vm locking a bit since the vm_*() calls take mmap_sem internally
+ */
+#ifndef do_mmap
+# define LINUX_NO_DOMMAP
+# define MY_DO_MMAP(a,b,c,d,e,f) vm_mmap(a, b, c, d, e, (f) >> PAGE_SHIFT)
+# define MY_DO_MUNMAP(a,b,c) vm_munmap(b, c)
+#else
+# undef LINUX_NO_DOMMAP
+# define MY_DO_MMAP(a,b,c,d,e,f) do_mmap(a, b, c, d, e, f)
+# define MY_DO_MUNMAP(a,b,c)					\
+	{							\
+		down_write(&(a)->mmap_sem);			\
+		do_munmap(a, b, c);				\
+		up_write(&(a)->mmap_sem);			\
+	}
+#endif
+
 #ifndef MY_DO_MUNMAP
 # define MY_DO_MUNMAP(a,b,c) do_munmap(a, b, c)
 #endif