[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>

1 files changed, 9 insertions, 4 deletions

diff --git a/include/net/tcp.h b/include/net/tcp.h
index ec9e20c27179..afe41c5de2f2 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -721,11 +721,16 @@ static inline int tcp_ack_scheduled(struct tcp_sock *tp)
         return tp->ack.pending&TCP_ACK_SCHED;
 }
 
-static __inline__ void tcp_dec_quickack_mode(struct tcp_sock *tp)
+static __inline__ void tcp_dec_quickack_mode(struct tcp_sock *tp, unsigned int pkts)
 {
-        if (tp->ack.quick && --tp->ack.quick == 0) {
-                /* Leaving quickack mode we deflate ATO. */
-                tp->ack.ato = TCP_ATO_MIN;
+        if (tp->ack.quick) {
+                if (pkts >= tp->ack.quick) {
+                        tp->ack.quick = 0;
+
+                        /* Leaving quickack mode we deflate ATO. */
+                        tp->ack.ato = TCP_ATO_MIN;
+                } else
+                        tp->ack.quick -= pkts;
         }
 }