From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Mon, 23 May 2011 11:02:42 +0000 (+0000)
Subject: sch_sfq: avoid giving spurious NET_XMIT_CN signals
X-Git-Tag: v2.6.39.1~102
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=9df49f2bfe862573911a080c75a6d81113c5c81d;p=pandora-kernel.git

sch_sfq: avoid giving spurious NET_XMIT_CN signals

[ Upstream commit 8efa885406359af300d46910642b50ca82c0fe47 ]

While chasing a possible net_sched bug, I found that IP fragments have
litle chance to pass a congestioned SFQ qdisc :

- Say SFQ qdisc is full because one flow is non responsive.
- ip_fragment() wants to send two fragments belonging to an idle flow.
- sfq_enqueue() queues first packet, but see queue limit reached :
- sfq_enqueue() drops one packet from 'big consumer', and returns
NET_XMIT_CN.
- ip_fragment() cancel remaining fragments.

This patch restores fairness, making sure we return NET_XMIT_CN only if
we dropped a packet from the same flow.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
CC: Patrick McHardy <kaber@trash.net>
CC: Jarek Poplawski <jarkao2@gmail.com>
CC: Jamal Hadi Salim <hadi@cyberus.ca>
CC: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---

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