net/rds: rds_sendmsg should not discard payload_len

Commit 3db6e0d172c9 ("rds: use RCU to synchronize work-enqueue with connection teardown") modifies rds_sendmsg to avoid enqueueing work while a tear down is in progress. However, it also changed the return value of rds_sendmsg to that of rds_send_xmit instead of the payload_len. This means the user may incorrectly receive errno values when it should have simply received a payload of 0 while the peer attempts a reconnections. So this patch corrects the teardown handling code to only use the out error path in that case, thus restoring the original payload_len return value.

---
Changes in v2:
- Rebased on net/main to fix apply failure in v1

Changes in v3:
- Rebase to updated net/main

---
 net/rds/send.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

index 6e96f108473e..a1039e422a38 100644
@@ -1431,9 +1431,11 @@ int rds_sendmsg(struct socket *sock, struct msghdr *msg, size_t payload_len)
 		else
 			queue_delayed_work(cpath->cp_wq, &cpath->cp_send_w, 1);
 		rcu_read_unlock();
+
+		if (ret)
+			goto out;
 	}
-	if (ret)
-		goto out;
+
 	rds_message_put(rm);
 
 	for (ind = 0; ind < vct.indx; ind++)

2.43.0