[PATCH v2] migration/rdma: Fix cm_event used before being initialized

[Li Zhijian]

A segmentation fault was triggered when i try to abort a postcopy + rdma
migration.

since rdma_ack_cm_event releases a uninitialized cm_event in these case.

like below:
2496     ret = rdma_get_cm_event(rdma->channel, &cm_event);
2497     if (ret) {
2498         perror("rdma_get_cm_event after rdma_connect");
2499         ERROR(errp, "connecting to destination!");
2500         rdma_ack_cm_event(cm_event); <<<< cause segmentation fault
2501         goto err_rdma_source_connect;
2502     }

Refer to the rdma_get_cm_event() code, cm_event will be
updated/changed only if rdma_get_cm_event() returns 0. So it's okey to
remove the ack in error patch.

Signed-off-by: Li Zhijian <lizhijian@cn.fujitsu.com>

---
V2: remove ack from the error patch (Dave)
---
 migration/rdma.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/migration/rdma.c b/migration/rdma.c
index 00eac34232..41726cc74a 100644
--- a/migration/rdma.c
+++ b/migration/rdma.c
@@ -2497,7 +2497,6 @@ static int qemu_rdma_connect(RDMAContext *rdma, Error 
**errp)
     if (ret) {
         perror("rdma_get_cm_event after rdma_connect");
         ERROR(errp, "connecting to destination!");
-        rdma_ack_cm_event(cm_event);
         goto err_rdma_source_connect;
     }
 
-- 
2.30.2