From: Jarek Poplawski <jarkao2@o2.pl>
Date: Fri, 2 Feb 2007 21:15:00 +0000 (-0800)
Subject: [PATCH] TCP: rare bad TCP checksum with 2.6.19
X-Git-Tag: v2.6.19.3~7
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=26cc0cab4c76d353c8f72fe3fe3e822d738f5c13;p=thirdparty%2Fkernel%2Fstable.git

[PATCH] TCP: rare bad TCP checksum with 2.6.19

The patch "Replace CHECKSUM_HW by CHECKSUM_PARTIAL/CHECKSUM_COMPLETE"
changed to unconditional copying of ip_summed field from collapsed
skb. This patch reverts this change.

The majority of substantial work including heavy testing
and diagnosing by: Michael Tokarev <mjt@tls.msk.ru>
Possible reasons pointed by: Herbert Xu and Patrick McHardy.

Signed-off-by: Jarek Poplawski <jarkao2@o2.pl>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>
---

diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index ca406157724c5..8b8334c836f58 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -1590,7 +1590,8 @@ static void tcp_retrans_try_collapse(struct sock *sk, struct sk_buff *skb, int m
 
 		memcpy(skb_put(skb, next_skb_size), next_skb->data, next_skb_size);
 
-		skb->ip_summed = next_skb->ip_summed;
+		if (next_skb->ip_summed == CHECKSUM_PARTIAL)
+			skb->ip_summed = CHECKSUM_PARTIAL;
 
 		if (skb->ip_summed != CHECKSUM_PARTIAL)
 			skb->csum = csum_block_add(skb->csum, next_skb->csum, skb_size);