[PATCH 2/3] migration/rdma: Post initial receive before accepting

[Yanfei Xu]

The source return-path thread can send READY before the destination has
posted its initial receive.  Since RNR retries default to zero, the send
can fail and abort migration.

Post the initial receive before rdma_accept() to close this window.

Fixes: 55cc1b5937a8 ("migration: create a dedicated connection for rdma return 
path")
Signed-off-by: Yanfei Xu <yanfei...@bytedance.com>
---
 migration/rdma.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/migration/rdma.c b/migration/rdma.c
index e17ace62b0..6e8436ccc1 100644
--- a/migration/rdma.c
+++ b/migration/rdma.c
@@ -3263,6 +3263,12 @@ static int qemu_rdma_accept(RDMAContext *rdma)
         }
     }
 
+    ret = qemu_rdma_post_recv_control(rdma, RDMA_WRID_READY, &err);
+    if (ret < 0) {
+        error_report_err(err);
+        goto err_rdma_dest_wait;
+    }
+
     /* Accept the second connection request for return path */
     if ((migrate_postcopy() || migrate_return_path())
         && !rdma->is_return_path) {
@@ -3295,12 +3301,6 @@ static int qemu_rdma_accept(RDMAContext *rdma)
     rdma_ack_cm_event(cm_event);
     rdma->connected = true;
 
-    ret = qemu_rdma_post_recv_control(rdma, RDMA_WRID_READY, &err);
-    if (ret < 0) {
-        error_report_err(err);
-        goto err_rdma_dest_wait;
-    }
-
     qemu_rdma_dump_gid("dest_connect", rdma->cm_id);
 
     return 0;
-- 
2.20.1