Commit ee80d1eb authored by Willem de Bruijn's avatar Willem de Bruijn Committed by David S. Miller
Browse files

udp: add udp gso 



Implement generic segmentation offload support for udp datagrams. A
follow-up patch adds support to the protocol stack to generate such
packets.

UDP GSO is not UFO. UFO fragments a single large datagram. GSO splits
a large payload into a number of discrete UDP datagrams.

The implementation adds a GSO type SKB_UDP_GSO_L4 to differentiate it
from UFO (SKB_UDP_GSO).

IPPROTO_UDPLITE is excluded, as that protocol has no gso handler
registered.

[ Export __udp_gso_segment for ipv6. -DaveM ]

Signed-off-by: default avatarWillem de Bruijn <willemb@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 1cd7884d

include/linux/skbuff.h

+2 −0
Original line number Diff line number Diff line
@@ -573,6 +573,8 @@ enum { 
	SKB_GSO_ESP = 1 << 15,



	SKB_GSO_UDP = 1 << 16,



	SKB_GSO_UDP_L4 = 1 << 17,

};



#if BITS_PER_LONG > 32

include/net/udp.h

+4 −0
Original line number Diff line number Diff line
@@ -174,6 +174,10 @@ struct sk_buff **udp_gro_receive(struct sk_buff **head, struct sk_buff *skb, 
				 struct udphdr *uh, udp_lookup_t lookup);

int udp_gro_complete(struct sk_buff *skb, int nhoff, udp_lookup_t lookup);



struct sk_buff *__udp_gso_segment(struct sk_buff *gso_skb,

				  netdev_features_t features,

				  unsigned int mss, __sum16 check);



static inline struct udphdr *udp_gro_udphdr(struct sk_buff *skb)

{

	struct udphdr *uh;

net/core/skbuff.c

+2 −0
Original line number Diff line number Diff line
@@ -4940,6 +4940,8 @@ static unsigned int skb_gso_transport_seglen(const struct sk_buff *skb) 
		thlen = tcp_hdrlen(skb);

	} else if (unlikely(skb_is_gso_sctp(skb))) {

		thlen = sizeof(struct sctphdr);

	} else if (shinfo->gso_type & SKB_GSO_UDP_L4) {

		thlen = sizeof(struct udphdr);

	}

	/* UFO sets gso_size to the size of the fragmentation

	 * payload, i.e. the size of the L4 (UDP) header is already

net/ipv4/udp_offload.c

+52 −1
Original line number Diff line number Diff line
@@ -187,6 +187,54 @@ out_unlock: 
}

EXPORT_SYMBOL(skb_udp_tunnel_segment);



struct sk_buff *__udp_gso_segment(struct sk_buff *gso_skb,

				  netdev_features_t features,

				  unsigned int mss, __sum16 check)

{

	struct sk_buff *segs, *seg;

	unsigned int hdrlen;

	struct udphdr *uh;



	if (gso_skb->len <= sizeof(*uh) + mss)

		return ERR_PTR(-EINVAL);



	hdrlen = gso_skb->data - skb_mac_header(gso_skb);

	skb_pull(gso_skb, sizeof(*uh));



	segs = skb_segment(gso_skb, features);

	if (unlikely(IS_ERR_OR_NULL(segs)))

		return segs;



	for (seg = segs; seg; seg = seg->next) {

		uh = udp_hdr(seg);

		uh->len = htons(seg->len - hdrlen);

		uh->check = check;



		/* last packet can be partial gso_size */

		if (!seg->next)

			csum_replace2(&uh->check, htons(mss),

				      htons(seg->len - hdrlen - sizeof(*uh)));

	}



	return segs;

}

EXPORT_SYMBOL_GPL(__udp_gso_segment);



static struct sk_buff *__udp4_gso_segment(struct sk_buff *gso_skb,

					  netdev_features_t features)

{

	const struct iphdr *iph = ip_hdr(gso_skb);

	unsigned int mss = skb_shinfo(gso_skb)->gso_size;



	if (!can_checksum_protocol(features, htons(ETH_P_IP)))

		return ERR_PTR(-EIO);



	return __udp_gso_segment(gso_skb, features, mss,

				 udp_v4_check(sizeof(struct udphdr) + mss,

					      iph->saddr, iph->daddr, 0));

}

EXPORT_SYMBOL_GPL(__udp4_gso_segment);



static struct sk_buff *udp4_ufo_fragment(struct sk_buff *skb,

					 netdev_features_t features)

{
@@ -203,12 +251,15 @@ static struct sk_buff *udp4_ufo_fragment(struct sk_buff *skb, 
		goto out;

	}



	if (!(skb_shinfo(skb)->gso_type & SKB_GSO_UDP))

	if (!(skb_shinfo(skb)->gso_type & (SKB_GSO_UDP | SKB_GSO_UDP_L4)))

		goto out;



	if (!pskb_may_pull(skb, sizeof(struct udphdr)))

		goto out;



	if (skb_shinfo(skb)->gso_type & SKB_GSO_UDP_L4)

		return __udp4_gso_segment(skb, features);



	mss = skb_shinfo(skb)->gso_size;

	if (unlikely(skb->len <= mss))

		goto out;

net/ipv6/ip6_offload.c

+4 −2
Original line number Diff line number Diff line
@@ -88,9 +88,11 @@ static struct sk_buff *ipv6_gso_segment(struct sk_buff *skb, 


	if (skb->encapsulation &&

	    skb_shinfo(skb)->gso_type & (SKB_GSO_IPXIP4 | SKB_GSO_IPXIP6))

		udpfrag = proto == IPPROTO_UDP && encap;

		udpfrag = proto == IPPROTO_UDP && encap &&

			  (skb_shinfo(skb)->gso_type & SKB_GSO_UDP);

	else

		udpfrag = proto == IPPROTO_UDP && !skb->encapsulation;

		udpfrag = proto == IPPROTO_UDP && !skb->encapsulation &&

			  (skb_shinfo(skb)->gso_type & SKB_GSO_UDP);



	ops = rcu_dereference(inet6_offloads[proto]);

	if (likely(ops && ops->callbacks.gso_segment)) {

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