RDS: TCP: Simplify reconnect to avoid duelling reconnnect attempts

When reconnecting, the peer with the smaller IP address will initiate
the reconnect, to avoid needless duelling SYN issues.

Acked-by: Santosh Shilimkar <santosh.shilimkar@oracle.com>
Signed-off-by: Sowmini Varadhan <sowmini.varadhan@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/rds/connection.c

@@ -355,9 +355,7 @@ void rds_conn_shutdown(struct rds_conn_path *cp)
 	rcu_read_lock();
 	if (!hlist_unhashed(&conn->c_hash_node)) {
 		rcu_read_unlock();
-		if (conn->c_trans->t_type != RDS_TRANS_TCP ||
-		    cp->cp_outgoing == 1)
-			rds_queue_reconnect(cp);
+		rds_queue_reconnect(cp);
 	} else {
 		rcu_read_unlock();
 	}

net/rds/threads.c

@@ -125,6 +125,11 @@ void rds_queue_reconnect(struct rds_conn_path *cp)
 	  conn, &conn->c_laddr, &conn->c_faddr,
 	  cp->cp_reconnect_jiffies);
 
+	/* let peer with smaller addr initiate reconnect, to avoid duels */
+	if (conn->c_trans->t_type == RDS_TRANS_TCP &&
+	    conn->c_laddr > conn->c_faddr)
+		return;
+
 	set_bit(RDS_RECONNECT_PENDING, &cp->cp_flags);
 	if (cp->cp_reconnect_jiffies == 0) {
 		cp->cp_reconnect_jiffies = rds_sysctl_reconnect_min_jiffies;