Commit 0718bcc0 authored by Herbert Xu's avatar Herbert Xu Committed by David S. Miller
Browse files

[NET]: Fix CHECKSUM_HW GSO problems. 



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: default avatarHerbert Xu <herbert@gondor.apana.org.au>
Acked-by: default avatarMichael Chan <mchan@broadcom.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 3ba07e65

net/ipv4/tcp.c

+11 −11
Original line number Diff line number Diff line
@@ -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;