[TCP]: Fix quick-ack decrementing with TSO.

On each packet output, we call tcp_dec_quickack_mode()
if the ACK flag is set.  It drops tp->ack.quick until
it hits zero, at which time we deflate the ATO value.

When doing TSO, we are emitting multiple packets with
ACK set, so we should decrement tp->ack.quick that many
segments.

Note that, unlike this case, tcp_enter_cwr() should not
take the tcp_skb_pcount(skb) into consideration.  That
function, one time, readjusts tp->snd_cwnd and moves
into TCP_CA_CWR state.

Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 0e17c24..389deeb 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -140,11 +140,11 @@
 		tp->ack.pingpong = 1;
 }
 
-static __inline__ void tcp_event_ack_sent(struct sock *sk)
+static __inline__ void tcp_event_ack_sent(struct sock *sk, unsigned int pkts)
 {
 	struct tcp_sock *tp = tcp_sk(sk);
 
-	tcp_dec_quickack_mode(tp);
+	tcp_dec_quickack_mode(tp, pkts);
 	tcp_clear_xmit_timer(sk, TCP_TIME_DACK);
 }
 
@@ -355,7 +355,7 @@
 		tp->af_specific->send_check(sk, th, skb->len, skb);
 
 		if (tcb->flags & TCPCB_FLAG_ACK)
-			tcp_event_ack_sent(sk);
+			tcp_event_ack_sent(sk, tcp_skb_pcount(skb));
 
 		if (skb->len != tcp_header_size)
 			tcp_event_data_sent(tp, skb, sk);