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authorEric Dumazet <edumazet@google.com>2018-06-27 08:47:21 -0700
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2018-08-03 07:50:45 +0200
commit0a2f6725115dc17b97294403a5afca830c64e48a (patch)
tree74f4d2d5d6dcf5504379d8175423627761edea98
parent1f04d750f6688c0fe0cc13fd05d5744d1e7b50c3 (diff)
tcp: add one more quick ack after after ECN events
[ Upstream commit 15ecbe94a45ef88491ca459b26efdd02f91edb6d ] Larry Brakmo proposal ( https://patchwork.ozlabs.org/patch/935233/ tcp: force cwnd at least 2 in tcp_cwnd_reduction) made us rethink about our recent patch removing ~16 quick acks after ECN events. tcp_enter_quickack_mode(sk, 1) makes sure one immediate ack is sent, but in the case the sender cwnd was lowered to 1, we do not want to have a delayed ack for the next packet we will receive. Fixes: 522040ea5fdd ("tcp: do not aggressively quick ack after ECN events") Signed-off-by: Eric Dumazet <edumazet@google.com> Reported-by: Neal Cardwell <ncardwell@google.com> Cc: Lawrence Brakmo <brakmo@fb.com> Acked-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--net/ipv4/tcp_input.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 124be1636efe..bdabd748f4bc 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -261,7 +261,7 @@ static void __tcp_ecn_check_ce(struct sock *sk, const struct sk_buff *skb)
* it is probably a retransmit.
*/
if (tp->ecn_flags & TCP_ECN_SEEN)
- tcp_enter_quickack_mode(sk, 1);
+ tcp_enter_quickack_mode(sk, 2);
break;
case INET_ECN_CE:
if (tcp_ca_needs_ecn(sk))
@@ -269,7 +269,7 @@ static void __tcp_ecn_check_ce(struct sock *sk, const struct sk_buff *skb)
if (!(tp->ecn_flags & TCP_ECN_DEMAND_CWR)) {
/* Better not delay acks, sender can have a very low cwnd */
- tcp_enter_quickack_mode(sk, 1);
+ tcp_enter_quickack_mode(sk, 2);
tp->ecn_flags |= TCP_ECN_DEMAND_CWR;
}
tp->ecn_flags |= TCP_ECN_SEEN;