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[NET]: Fix CHECKSUM_HW GSO problems.

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Fix checksum problems in the GSO code path for CHECKSUM_HW packets.

The ipv4 TCP pseudo header checksum has to be adjusted for GSO
segmented packets.

The adjustment is needed because the length field in the pseudo-header
changes.  However, because we have the inequality oldlen > newlen, we
know that delta = (u16)~oldlen + newlen is still a 16-bit quantity.
This also means that htonl(delta) + th->check still fits in 32 bits.
Therefore we don't have to use csum_add on this operations.

This is based on a patch by Michael Chan <mchan@broadcom.com>.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Acked-by: Michael Chan <mchan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Herbert Xu 2006-06-25 23:55:46 -07:00 committed by David S. Miller
parent 3ba07e65b2
commit 0718bcc09b
1 changed files with 11 additions and 11 deletions
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22
net/ipv4/tcp.c
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@ -2166,7 +2166,7 @@ struct sk_buff *tcp_tso_segment(struct sk_buff *skb, int sg)
if (!pskb_may_pull(skb, thlen))
goto out;
oldlen = ~htonl(skb->len);
oldlen = (u16)~skb->len;
__skb_pull(skb, thlen);
segs = skb_segment(skb, sg);
@ -2174,7 +2174,7 @@ struct sk_buff *tcp_tso_segment(struct sk_buff *skb, int sg)
goto out;
len = skb_shinfo(skb)->gso_size;
delta = csum_add(oldlen, htonl(thlen + len));
delta = htonl(oldlen + (thlen + len));
skb = segs;
th = skb->h.th;
@ -2183,10 +2183,10 @@ struct sk_buff *tcp_tso_segment(struct sk_buff *skb, int sg)
do {
th->fin = th->psh = 0;
if (skb->ip_summed == CHECKSUM_NONE) {
th->check = csum_fold(csum_partial(
skb->h.raw, thlen, csum_add(skb->csum, delta)));
}
th->check = ~csum_fold(th->check + delta);
if (skb->ip_summed != CHECKSUM_HW)
th->check = csum_fold(csum_partial(skb->h.raw, thlen,
skb->csum));
seq += len;
skb = skb->next;
@ -2196,11 +2196,11 @@ struct sk_buff *tcp_tso_segment(struct sk_buff *skb, int sg)
th->cwr = 0;
} while (skb->next);
if (skb->ip_summed == CHECKSUM_NONE) {
delta = csum_add(oldlen, htonl(skb->tail - skb->h.raw));
th->check = csum_fold(csum_partial(
skb->h.raw, thlen, csum_add(skb->csum, delta)));
}
delta = htonl(oldlen + (skb->tail - skb->h.raw) + skb->data_len);
th->check = ~csum_fold(th->check + delta);
if (skb->ip_summed != CHECKSUM_HW)
th->check = csum_fold(csum_partial(skb->h.raw, thlen,
skb->csum));
out:
return segs;