From mboxrd@z Thu Jan  1 00:00:00 1970
From: David Miller <davem@davemloft.net>
Subject: Re: [PATCH] tcp: ECN blackhole should not force quickack mode
Date: Tue, 27 Sep 2011 00:59:05 -0400 (EDT)
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From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Fri, 23 Sep 2011 08:02:19 +0200

> While playing with a new ADSL box at home, I discovered that ECN
> blackhole can trigger suboptimal quickack mode on linux : We send one
> ACK for each incoming data frame, without any delay and eventual
> piggyback.
> 
> This is because TCP_ECN_check_ce() considers that if no ECT is seen on a
> segment, this is because this segment was a retransmit.
> 
> Refine this heuristic and apply it only if we seen ECT in a previous
> segment, to detect ECN blackhole at IP level.
> 
> Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>

Applied to net-next, thanks Eric.