[patch 53/59] TCP: rare bad TCP checksum with 2.6.19

Chris Wright
2007-02-03T02:45:18Z

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-stable review patch. If anyone has any objections, please let us know.
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From: Jarek Poplawski <jarkao2@o2.pl>

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>
---
net/ipv4/tcp_output.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

--- linux-2.6.19.2.orig/net/ipv4/tcp_output.c
+++ linux-2.6.19.2/net/ipv4/tcp_output.c
@@ -1590,7 +1590,8 @@ static void tcp_retrans_try_collapse(str

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);

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