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net: core: don't account for udp header size when computing seglen

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In case of tcp, gso_size contains the tcpmss.

For UFO (udp fragmentation offloading) skbs, gso_size is the fragment
payload size, i.e. we must not account for udp header size.

Otherwise, when using virtio drivers, a to-be-forwarded UFO GSO packet
will be needlessly fragmented in the forward path, because we think its
individual segments are too large for the outgoing link.

Fixes: fe6cc55f3a ("net: ip, ipv6: handle gso skbs in forwarding path")
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Reported-by: Tobias Brunner <tobias@strongswan.org>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Florian Westphal 2014-04-09 10:28:50 +02:00 committed by David S. Miller
parent f34c4a35d8
commit 6d39d589bb
1 changed files with 7 additions and 5 deletions
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12
net/core/skbuff.c
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@ -3937,12 +3937,14 @@ EXPORT_SYMBOL_GPL(skb_scrub_packet);
unsigned int skb_gso_transport_seglen(const struct sk_buff *skb) unsigned int skb_gso_transport_seglen(const struct sk_buff *skb)
{ {
const struct skb_shared_info *shinfo = skb_shinfo(skb); const struct skb_shared_info *shinfo = skb_shinfo(skb);
unsigned int hdr_len;
if (likely(shinfo->gso_type & (SKB_GSO_TCPV4 | SKB_GSO_TCPV6))) if (likely(shinfo->gso_type & (SKB_GSO_TCPV4 | SKB_GSO_TCPV6)))
hdr_len = tcp_hdrlen(skb); return tcp_hdrlen(skb) + shinfo->gso_size;
else
hdr_len = sizeof(struct udphdr); /* UFO sets gso_size to the size of the fragmentation
return hdr_len + shinfo->gso_size; * payload, i.e. the size of the L4 (UDP) header is already
* accounted for.
*/
return shinfo->gso_size;
} }
EXPORT_SYMBOL_GPL(skb_gso_transport_seglen); EXPORT_SYMBOL_GPL(skb_gso_transport_seglen);