From: Jarek Poplawski <jarkao2@o2.pl>
Date: Wed, 24 Jan 2007 06:07:12 +0000 (-0800)
Subject: [TCP]: rare bad TCP checksum with 2.6.19
X-Git-Tag: v3.12-rc1~31878^2~3
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=52d570aabe921663a987b2e4bae2bdc411cee480;p=kernel%2Fkernel-generic.git

[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>
---

diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 32c1a97..23e32c8 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -1650,7 +1650,8 @@ 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);