[TIPC]: Skip connection flow control in connectionless sockets

This patch optimizes the receive path for SOCK_DGRAM and SOCK_RDM
messages by skipping over code that handles connection-based flow
control.
Signed-off-by: NAllan Stephens <allan.stephens@windriver.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/tipc/socket.c

@@ -919,7 +919,8 @@ static int recv_msg(struct kiocb *iocb, struct socket *sock,
 	/* Consume received message (optional) */
 
 	if (likely(!(flags & MSG_PEEK))) {
-		if (unlikely(++tsock->p->conn_unacked >= TIPC_FLOW_CONTROL_WIN))
+		if ((sock->state != SS_READY) &&
+		    (++tsock->p->conn_unacked >= TIPC_FLOW_CONTROL_WIN))
 			tipc_acknowledge(tsock->p->ref, tsock->p->conn_unacked);
 		advance_queue(tsock);
 	}