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Commit 6d39d589 authored by Florian Westphal's avatar Florian Westphal Committed by David S. Miller
Browse files

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



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: fe6cc55f ("net: ip, ipv6: handle gso skbs in forwarding path")
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Reported-by: default avatarTobias Brunner <tobias@strongswan.org>
Signed-off-by: default avatarFlorian Westphal <fw@strlen.de>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent f34c4a35

net/core/skbuff.c

+7 −5
Original line number Original line Diff line number Diff line
@@ -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);