From: Eric Dumazet <edumazet@google.com>
Date: Fri, 19 Apr 2013 07:19:48 +0000 (+0000)
Subject: tcp: call tcp_replace_ts_recent() from tcp_ack()
X-Git-Tag: v3.2.45~22
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=60986f51c3db46081a9cb9fd469ad65cd1ccb833;p=pandora-kernel.git

tcp: call tcp_replace_ts_recent() from tcp_ack()

[ Upstream commit 12fb3dd9dc3c64ba7d64cec977cca9b5fb7b1d4e ]

commit bd090dfc634d (tcp: tcp_replace_ts_recent() should not be called
from tcp_validate_incoming()) introduced a TS ecr bug in slow path
processing.

1 A > B P. 1:10001(10000) ack 1 <nop,nop,TS val 1001 ecr 200>
2 B < A . 1:1(0) ack 1 win 257 <sack 9001:10001,TS val 300 ecr 1001>
3 A > B . 1:1001(1000) ack 1 win 227 <nop,nop,TS val 1002 ecr 200>
4 A > B . 1001:2001(1000) ack 1 win 227 <nop,nop,TS val 1002 ecr 200>

(ecr 200 should be ecr 300 in packets 3 & 4)

Problem is tcp_ack() can trigger send of new packets (retransmits),
reflecting the prior TSval, instead of the TSval contained in the
currently processed incoming packet.

Fix this by calling tcp_replace_ts_recent() from tcp_ack() after the
checks, but before the actions.

Reported-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Neal Cardwell <ncardwell@google.com>
Acked-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
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