quorum: fix quorum_aio_cancel()

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>
Signed-off-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

diff --git a/block/quorum.c b/block/quorum.c
index 093382e8f50e65a70633a0d56de499bfb05b5ec3..41c4249547d9c8dd2789b85fd766b00fc98180f8 100644 (file)
--- a/block/quorum.c
+++ b/block/quorum.c
@@ -138,7 +138,9 @@ 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);
+        }
     }
 
     g_free(acb->qcrs);