Commit 99b4dd9f authored Jan 29, 2016 by Yuchung Cheng Committed by David S. Miller Jan 29, 2016

tcp: avoid cwnd undo after receiving ECN



RFC 4015 section 3.4 says the TCP sender MUST refrain from
reversing the congestion control state when the ACK signals
congestion through the ECN-Echo flag. Currently we may not
always do that when prior_ssthresh is reset upon receiving
ACKs with ECE marks. This patch fixes that.

Signed-off-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent 3d45296a

net/ipv4/tcp_input.c

+0 −2

Original line number	Diff line number	Diff line
		@@ -2366,8 +2366,6 @@ static void tcp_undo_cwnd_reduction(struct sock *sk, bool unmark_loss)
		tp->snd_ssthresh = tp->prior_ssthresh;
		tcp_ecn_withdraw_cwr(tp);
		}
		} else {
		tp->snd_cwnd = max(tp->snd_cwnd, tp->snd_ssthresh);
		}
		tp->snd_cwnd_stamp = tcp_time_stamp;
		tp->undo_marker = 0;

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