[Qemu-devel] [PATCH 5/8] quorum: fix quorum_aio_cancel()

[Liu Yuan <namei.unix@gmail.com>]

For a fifo read pattern, we only have one running aio (possible other cases that
has less number than num_children in the future), so we need to check if
.acb is NULL against bdrv_aio_cancel() to avoid segfault.

Cc: Eric Blake <eblake@redhat.com>
Cc: Benoit Canet <benoit@irqsave.net>
Cc: Kevin Wolf <kwolf@redhat.com>
Cc: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Liu Yuan <namei.unix@gmail.com>
---
 block/quorum.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/block/quorum.c b/block/quorum.c
index 9e056d6..b9eeda3 100644
--- a/block/quorum.c
+++ b/block/quorum.c
@@ -144,7 +144,9 @@ static void quorum_aio_cancel(BlockDriverAIOCB *blockacb)
 
     /* cancel all callbacks */
     for (i = 0; i < s->num_children; i++) {
-        bdrv_aio_cancel(acb->qcrs[i].aiocb);
+        if (acb->qcrs[i].aiocb) {
+            bdrv_aio_cancel(acb->qcrs[i].aiocb);
+        }
     }
 
     quorum_aio_release(acb);
-- 
1.9.1