RDS: check for congestion updates during rds_send_xmit

Ensure we don't keep sending the data if the link is congested.

Reviewed-by: Ajaykumar Hotchandani <ajaykumar.hotchandani@oracle.com>
Signed-off-by: Santosh Shilimkar <ssantosh@kernel.org>
Signed-off-by: Santosh Shilimkar <santosh.shilimkar@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/rds/send.c

@@ -411,7 +411,8 @@ over_batch:
 	 */
 	if (ret == 0) {
 		smp_mb();
-		if (!list_empty(&conn->c_send_queue) &&
+		if ((test_bit(0, &conn->c_map_queued) ||
+		     !list_empty(&conn->c_send_queue)) &&
 		    send_gen == conn->c_send_gen) {
 			rds_stats_inc(s_send_lock_queue_raced);
 			goto restart;