Commit c22bdca9 authored Jan 28, 2015 by Neal Cardwell Committed by David S. Miller Jan 28, 2015

tcp: fix stretch ACK bugs in Reno



Change Reno to properly handle stretch ACKs in additive increase mode
by passing in the count of ACKed packets to tcp_cong_avoid_ai().

In addition, if snd_cwnd crosses snd_ssthresh during slow start
processing, and we then exit slow start mode, we need to carry over
any remaining "credit" for packets ACKed and apply that to additive
increase by passing this remaining "acked" count to
tcp_cong_avoid_ai().

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

parent 814d488c

net/ipv4/tcp_cong.c

+6 −4

Original line number	Diff line number	Diff line
		@@ -335,11 +335,13 @@ void tcp_reno_cong_avoid(struct sock *sk, u32 ack, u32 acked)
		return;

		/* In "safe" area, increase. */
		if (tp->snd_cwnd <= tp->snd_ssthresh)
		tcp_slow_start(tp, acked);
		if (tp->snd_cwnd <= tp->snd_ssthresh) {
		acked = tcp_slow_start(tp, acked);
		if (!acked)
		return;
		}
		/* In dangerous area, increase slowly. */
		else
		tcp_cong_avoid_ai(tp, tp->snd_cwnd, 1);
		tcp_cong_avoid_ai(tp, tp->snd_cwnd, acked);
		}
		EXPORT_SYMBOL_GPL(tcp_reno_cong_avoid);

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