From: Eric Dumazet <edumazet@google.com>
Date: Wed, 23 May 2012 17:51:37 +0000 (+0000)
Subject: tcp: take care of overlaps in tcp_try_coalesce()
X-Git-Tag: v3.5-rc1~101^2
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=1ca7ee30630e1022dbcf1b51be20580815ffab73;p=pandora-kernel.git

tcp: take care of overlaps in tcp_try_coalesce()

Sergio Correia reported following warning :

WARNING: at net/ipv4/tcp.c:1301 tcp_cleanup_rbuf+0x4f/0x110()

WARN(skb && !before(tp->copied_seq, TCP_SKB_CB(skb)->end_seq),
     "cleanup rbuf bug: copied %X seq %X rcvnxt %X\n",
     tp->copied_seq, TCP_SKB_CB(skb)->end_seq, tp->rcv_nxt);

It appears TCP coalescing, and more specifically commit b081f85c297
(net: implement tcp coalescing in tcp_queue_rcv()) should take care of
possible segment overlaps in receive queue. This was properly done in
the case of out_or_order_queue by the caller.

For example, segment at tail of queue have sequence 1000-2000, and we
add a segment with sequence 1500-2500.
This can happen in case of retransmits.

In this case, just don't do the coalescing.

Reported-by: Sergio Correia <lists@uece.net>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Tested-by: Sergio Correia <lists@uece.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
---

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