commit 9a4d5ca60772e09d0cbac01f1b4778aa68e00eaa
author Jeff Cody <jcody@redhat.com> Wed Jul 23 17:22:57 2014 -0400
committer Kevin Wolf <kwolf@redhat.com> Fri Aug 15 15:07:14 2014 +0200
tree 2d42ce46e2fcc8a311d8ddc519494130b587b28e
parent 58803ce74f986785badfb2ef0f630e1cd97f52e5

block: allow bdrv_unref() to be passed NULL pointers

If bdrv_unref() is passed a NULL BDS pointer, it is safe to
exit with no operation.  This will allow cleanup code to blindly
call bdrv_unref() on a BDS that has been initialized to NULL.

Reviewed-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Jeff Cody <jcody@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

block.c

diff --git a/block.c b/block.c
index 6b29285..d7cb7d4 100644
--- a/block.c
+++ b/block.c
@@ -5381,6 +5381,9 @@
  * deleted. */
 void bdrv_unref(BlockDriverState *bs)
 {
+    if (!bs) {
+        return;
+    }
     assert(bs->refcnt > 0);
     if (--bs->refcnt == 0) {
         bdrv_delete(bs);