tcp: add one more quick ack after after ECN events
[ Upstream commitpull/10/head15ecbe94a4
] 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:522040ea5f
("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>
parent
1f04d750f6
commit
0a2f672511
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@ -261,7 +261,7 @@ static void __tcp_ecn_check_ce(struct sock *sk, const struct sk_buff *skb)
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* it is probably a retransmit.
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*/
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if (tp->ecn_flags & TCP_ECN_SEEN)
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tcp_enter_quickack_mode(sk, 1);
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tcp_enter_quickack_mode(sk, 2);
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break;
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case INET_ECN_CE:
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if (tcp_ca_needs_ecn(sk))
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@ -269,7 +269,7 @@ static void __tcp_ecn_check_ce(struct sock *sk, const struct sk_buff *skb)
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if (!(tp->ecn_flags & TCP_ECN_DEMAND_CWR)) {
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/* Better not delay acks, sender can have a very low cwnd */
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tcp_enter_quickack_mode(sk, 1);
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tcp_enter_quickack_mode(sk, 2);
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tp->ecn_flags |= TCP_ECN_DEMAND_CWR;
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}
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tp->ecn_flags |= TCP_ECN_SEEN;
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