net: core: don't account for udp header size when computing seglen (6d39d589) · Commits · 戴 / test

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: ("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>

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);

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