[deliverable/linux.git] / net / ipv4 / tcp_offload.c

/*
 *	IPV4 GSO/GRO offload support
 *	Linux INET implementation
 *
 *	This program is free software; you can redistribute it and/or
 *	modify it under the terms of the GNU General Public License
 *	as published by the Free Software Foundation; either version
 *	2 of the License, or (at your option) any later version.
 *
 *	TCPv4 GSO/GRO support
 */

#include <linux/skbuff.h>
#include <net/tcp.h>
#include <net/protocol.h>

static void tcp_gso_tstamp(struct sk_buff *skb, unsigned int ts_seq,
			   unsigned int seq, unsigned int mss)
{
	while (skb) {
		if (before(ts_seq, seq + mss)) {
			skb_shinfo(skb)->tx_flags |= SKBTX_SW_TSTAMP;
			skb_shinfo(skb)->tskey = ts_seq;
			return;
		}

		skb = skb->next;
		seq += mss;
	}
}

struct sk_buff *tcp_gso_segment(struct sk_buff *skb,
				netdev_features_t features)
{
	struct sk_buff *segs = ERR_PTR(-EINVAL);
	unsigned int sum_truesize = 0;
	struct tcphdr *th;
	unsigned int thlen;
	unsigned int seq;
	__be32 delta;
	unsigned int oldlen;
	unsigned int mss;
	struct sk_buff *gso_skb = skb;
	__sum16 newcheck;
	bool ooo_okay, copy_destructor;

	if (!pskb_may_pull(skb, sizeof(*th)))
		goto out;

	th = tcp_hdr(skb);
	thlen = th->doff * 4;
	if (thlen < sizeof(*th))
		goto out;

	if (!pskb_may_pull(skb, thlen))
		goto out;

	oldlen = (u16)~skb->len;
	__skb_pull(skb, thlen);

	mss = tcp_skb_mss(skb);
	if (unlikely(skb->len <= mss))
		goto out;

	if (skb_gso_ok(skb, features | NETIF_F_GSO_ROBUST)) {
		/* Packet is from an untrusted source, reset gso_segs. */
		int type = skb_shinfo(skb)->gso_type;

		if (unlikely(type &
			     ~(SKB_GSO_TCPV4 |
			       SKB_GSO_DODGY |
			       SKB_GSO_TCP_ECN |
			       SKB_GSO_TCPV6 |
			       SKB_GSO_GRE |
			       SKB_GSO_GRE_CSUM |
			       SKB_GSO_IPIP |
			       SKB_GSO_SIT |
			       SKB_GSO_MPLS |
			       SKB_GSO_UDP_TUNNEL |
			       SKB_GSO_UDP_TUNNEL_CSUM |
			       0) ||
			     !(type & (SKB_GSO_TCPV4 | SKB_GSO_TCPV6))))
			goto out;

		skb_shinfo(skb)->gso_segs = DIV_ROUND_UP(skb->len, mss);

		segs = NULL;
		goto out;
	}

	copy_destructor = gso_skb->destructor == tcp_wfree;
	ooo_okay = gso_skb->ooo_okay;
	/* All segments but the first should have ooo_okay cleared */
	skb->ooo_okay = 0;

	segs = skb_segment(skb, features);
	if (IS_ERR(segs))
		goto out;

	/* Only first segment might have ooo_okay set */
	segs->ooo_okay = ooo_okay;

	delta = htonl(oldlen + (thlen + mss));

	skb = segs;
	th = tcp_hdr(skb);
	seq = ntohl(th->seq);

	if (unlikely(skb_shinfo(gso_skb)->tx_flags & SKBTX_SW_TSTAMP))
		tcp_gso_tstamp(segs, skb_shinfo(gso_skb)->tskey, seq, mss);

	newcheck = ~csum_fold((__force __wsum)((__force u32)th->check +
					       (__force u32)delta));

	do {
		th->fin = th->psh = 0;
		th->check = newcheck;

		if (skb->ip_summed != CHECKSUM_PARTIAL)
			th->check = gso_make_checksum(skb, ~th->check);

		seq += mss;
		if (copy_destructor) {
			skb->destructor = gso_skb->destructor;
			skb->sk = gso_skb->sk;
			sum_truesize += skb->truesize;
		}
		skb = skb->next;
		th = tcp_hdr(skb);

		th->seq = htonl(seq);
		th->cwr = 0;
	} while (skb->next);

	/* Following permits TCP Small Queues to work well with GSO :
	 * The callback to TCP stack will be called at the time last frag
	 * is freed at TX completion, and not right now when gso_skb
	 * is freed by GSO engine
	 */
	if (copy_destructor) {
		swap(gso_skb->sk, skb->sk);
		swap(gso_skb->destructor, skb->destructor);
		sum_truesize += skb->truesize;
		atomic_add(sum_truesize - gso_skb->truesize,
			   &skb->sk->sk_wmem_alloc);
	}

	delta = htonl(oldlen + (skb_tail_pointer(skb) -
				skb_transport_header(skb)) +
		      skb->data_len);
	th->check = ~csum_fold((__force __wsum)((__force u32)th->check +
				(__force u32)delta));
	if (skb->ip_summed != CHECKSUM_PARTIAL)
		th->check = gso_make_checksum(skb, ~th->check);
out:
	return segs;
}

struct sk_buff **tcp_gro_receive(struct sk_buff **head, struct sk_buff *skb)
{
	struct sk_buff **pp = NULL;
	struct sk_buff *p;
	struct tcphdr *th;
	struct tcphdr *th2;
	unsigned int len;
	unsigned int thlen;
	__be32 flags;
	unsigned int mss = 1;
	unsigned int hlen;
	unsigned int off;
	int flush = 1;
	int i;

	off = skb_gro_offset(skb);
	hlen = off + sizeof(*th);
	th = skb_gro_header_fast(skb, off);
	if (skb_gro_header_hard(skb, hlen)) {
		th = skb_gro_header_slow(skb, hlen, off);
		if (unlikely(!th))
			goto out;
	}

	thlen = th->doff * 4;
	if (thlen < sizeof(*th))
		goto out;

	hlen = off + thlen;
	if (skb_gro_header_hard(skb, hlen)) {
		th = skb_gro_header_slow(skb, hlen, off);
		if (unlikely(!th))
			goto out;
	}

	skb_gro_pull(skb, thlen);

	len = skb_gro_len(skb);
	flags = tcp_flag_word(th);

	for (; (p = *head); head = &p->next) {
		if (!NAPI_GRO_CB(p)->same_flow)
			continue;

		th2 = tcp_hdr(p);

		if (*(u32 *)&th->source ^ *(u32 *)&th2->source) {
			NAPI_GRO_CB(p)->same_flow = 0;
			continue;
		}

		goto found;
	}

	goto out_check_final;

found:
	/* Include the IP ID check below from the inner most IP hdr */
	flush = NAPI_GRO_CB(p)->flush | NAPI_GRO_CB(p)->flush_id;
	flush |= (__force int)(flags & TCP_FLAG_CWR);
	flush |= (__force int)((flags ^ tcp_flag_word(th2)) &
		  ~(TCP_FLAG_CWR | TCP_FLAG_FIN | TCP_FLAG_PSH));
	flush |= (__force int)(th->ack_seq ^ th2->ack_seq);
	for (i = sizeof(*th); i < thlen; i += 4)
		flush |= *(u32 *)((u8 *)th + i) ^
			 *(u32 *)((u8 *)th2 + i);

	mss = tcp_skb_mss(p);

	flush |= (len - 1) >= mss;
	flush |= (ntohl(th2->seq) + skb_gro_len(p)) ^ ntohl(th->seq);

	if (flush || skb_gro_receive(head, skb)) {
		mss = 1;
		goto out_check_final;
	}

	p = *head;
	th2 = tcp_hdr(p);
	tcp_flag_word(th2) |= flags & (TCP_FLAG_FIN | TCP_FLAG_PSH);

out_check_final:
	flush = len < mss;
	flush |= (__force int)(flags & (TCP_FLAG_URG | TCP_FLAG_PSH |
					TCP_FLAG_RST | TCP_FLAG_SYN |
					TCP_FLAG_FIN));

	if (p && (!NAPI_GRO_CB(skb)->same_flow || flush))
		pp = head;

out:
	NAPI_GRO_CB(skb)->flush |= (flush != 0);

	return pp;
}

int tcp_gro_complete(struct sk_buff *skb)
{
	struct tcphdr *th = tcp_hdr(skb);

	skb->csum_start = (unsigned char *)th - skb->head;
	skb->csum_offset = offsetof(struct tcphdr, check);
	skb->ip_summed = CHECKSUM_PARTIAL;

	skb_shinfo(skb)->gso_segs = NAPI_GRO_CB(skb)->count;

	if (th->cwr)
		skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_ECN;

	return 0;
}
EXPORT_SYMBOL(tcp_gro_complete);

static int tcp_v4_gso_send_check(struct sk_buff *skb)
{
	const struct iphdr *iph;
	struct tcphdr *th;

	if (!pskb_may_pull(skb, sizeof(*th)))
		return -EINVAL;

	iph = ip_hdr(skb);
	th = tcp_hdr(skb);

	th->check = 0;
	skb->ip_summed = CHECKSUM_PARTIAL;
	__tcp_v4_send_check(skb, iph->saddr, iph->daddr);
	return 0;
}

static struct sk_buff **tcp4_gro_receive(struct sk_buff **head, struct sk_buff *skb)
{
	/* Use the IP hdr immediately proceeding for this transport */
	const struct iphdr *iph = skb_gro_network_header(skb);
	__wsum wsum;

	/* Don't bother verifying checksum if we're going to flush anyway. */
	if (NAPI_GRO_CB(skb)->flush)
		goto skip_csum;

	wsum = NAPI_GRO_CB(skb)->csum;

	switch (skb->ip_summed) {
	case CHECKSUM_NONE:
		wsum = skb_checksum(skb, skb_gro_offset(skb), skb_gro_len(skb),
				    0);

		/* fall through */

	case CHECKSUM_COMPLETE:
		if (!tcp_v4_check(skb_gro_len(skb), iph->saddr, iph->daddr,
				  wsum)) {
			skb->ip_summed = CHECKSUM_UNNECESSARY;
			break;
		}

		NAPI_GRO_CB(skb)->flush = 1;
		return NULL;
	}

skip_csum:
	return tcp_gro_receive(head, skb);
}

static int tcp4_gro_complete(struct sk_buff *skb, int thoff)
{
	const struct iphdr *iph = ip_hdr(skb);
	struct tcphdr *th = tcp_hdr(skb);

	th->check = ~tcp_v4_check(skb->len - thoff, iph->saddr,
				  iph->daddr, 0);
	skb_shinfo(skb)->gso_type |= SKB_GSO_TCPV4;

	return tcp_gro_complete(skb);
}

static const struct net_offload tcpv4_offload = {
	.callbacks = {
		.gso_send_check	=	tcp_v4_gso_send_check,
		.gso_segment	=	tcp_gso_segment,
		.gro_receive	=	tcp4_gro_receive,
		.gro_complete	=	tcp4_gro_complete,
	},
};

int __init tcpv4_offload_init(void)
{
	return inet_add_offload(&tcpv4_offload, IPPROTO_TCP);
}
Commit	Line	Data
28850dc7 DB	1	/*
	2	* IPV4 GSO/GRO offload support
	3	* Linux INET implementation
	4	*
	5	* This program is free software; you can redistribute it and/or
	6	* modify it under the terms of the GNU General Public License
	7	* as published by the Free Software Foundation; either version
	8	* 2 of the License, or (at your option) any later version.
	9	*
	10	* TCPv4 GSO/GRO support
	11	*/
	12
	13	#include <linux/skbuff.h>
	14	#include <net/tcp.h>
	15	#include <net/protocol.h>
	16
f066e2b0 WB	17	static void tcp_gso_tstamp(struct sk_buff *skb, unsigned int ts_seq,
f066e2b0 WB	18	unsigned int seq, unsigned int mss)
4ed2d765 WB	19	{
4ed2d765 WB	20	while (skb) {
f066e2b0 WB	21	if (before(ts_seq, seq + mss)) {
f066e2b0 WB	22	skb_shinfo(skb)->tx_flags \|= SKBTX_SW_TSTAMP;
4ed2d765 WB	23	skb_shinfo(skb)->tskey = ts_seq;
	24	return;
	25	}
	26
	27	skb = skb->next;
	28	seq += mss;
	29	}
	30	}
	31
28be6e07	32	struct sk_buff tcp_gso_segment(struct sk_buff skb,
28850dc7 DB	33	netdev_features_t features)
	34	{
	35	struct sk_buff *segs = ERR_PTR(-EINVAL);
0d08c42c	36	unsigned int sum_truesize = 0;
28850dc7 DB	37	struct tcphdr *th;
	38	unsigned int thlen;
	39	unsigned int seq;
	40	__be32 delta;
	41	unsigned int oldlen;
	42	unsigned int mss;
	43	struct sk_buff *gso_skb = skb;
	44	__sum16 newcheck;
	45	bool ooo_okay, copy_destructor;
	46
	47	if (!pskb_may_pull(skb, sizeof(*th)))
	48	goto out;
	49
	50	th = tcp_hdr(skb);
	51	thlen = th->doff * 4;
	52	if (thlen < sizeof(*th))
	53	goto out;
	54
	55	if (!pskb_may_pull(skb, thlen))
	56	goto out;
	57
	58	oldlen = (u16)~skb->len;
	59	__skb_pull(skb, thlen);
	60
	61	mss = tcp_skb_mss(skb);
	62	if (unlikely(skb->len <= mss))
	63	goto out;
	64
	65	if (skb_gso_ok(skb, features \| NETIF_F_GSO_ROBUST)) {
	66	/* Packet is from an untrusted source, reset gso_segs. */
	67	int type = skb_shinfo(skb)->gso_type;
	68
	69	if (unlikely(type &
	70	~(SKB_GSO_TCPV4 \|
	71	SKB_GSO_DODGY \|
	72	SKB_GSO_TCP_ECN \|
	73	SKB_GSO_TCPV6 \|
	74	SKB_GSO_GRE \|
4749c09c	75	SKB_GSO_GRE_CSUM \|
cb32f511	76	SKB_GSO_IPIP \|
61c1db7f	77	SKB_GSO_SIT \|
28850dc7 DB	78	SKB_GSO_MPLS \|
28850dc7 DB	79	SKB_GSO_UDP_TUNNEL \|
0f4f4ffa	80	SKB_GSO_UDP_TUNNEL_CSUM \|
28850dc7 DB	81	0) \|\|
	82	!(type & (SKB_GSO_TCPV4 \| SKB_GSO_TCPV6))))
	83	goto out;
	84
	85	skb_shinfo(skb)->gso_segs = DIV_ROUND_UP(skb->len, mss);
	86
	87	segs = NULL;
	88	goto out;
	89	}
	90
	91	copy_destructor = gso_skb->destructor == tcp_wfree;
	92	ooo_okay = gso_skb->ooo_okay;
	93	/* All segments but the first should have ooo_okay cleared */
	94	skb->ooo_okay = 0;
	95
	96	segs = skb_segment(skb, features);
	97	if (IS_ERR(segs))
	98	goto out;
	99
	100	/* Only first segment might have ooo_okay set */
	101	segs->ooo_okay = ooo_okay;
	102
	103	delta = htonl(oldlen + (thlen + mss));
	104
	105	skb = segs;
	106	th = tcp_hdr(skb);
	107	seq = ntohl(th->seq);
	108
4ed2d765 WB	109	if (unlikely(skb_shinfo(gso_skb)->tx_flags & SKBTX_SW_TSTAMP))
	110	tcp_gso_tstamp(segs, skb_shinfo(gso_skb)->tskey, seq, mss);
	111
28850dc7 DB	112	newcheck = ~csum_fold((__force __wsum)((__force u32)th->check +
	113	(__force u32)delta));
	114
	115	do {
	116	th->fin = th->psh = 0;
	117	th->check = newcheck;
	118
	119	if (skb->ip_summed != CHECKSUM_PARTIAL)
e9c3a24b	120	th->check = gso_make_checksum(skb, ~th->check);
28850dc7 DB	121
	122	seq += mss;
	123	if (copy_destructor) {
	124	skb->destructor = gso_skb->destructor;
	125	skb->sk = gso_skb->sk;
0d08c42c	126	sum_truesize += skb->truesize;
28850dc7 DB	127	}
	128	skb = skb->next;
	129	th = tcp_hdr(skb);
	130
	131	th->seq = htonl(seq);
	132	th->cwr = 0;
	133	} while (skb->next);
	134
	135	/* Following permits TCP Small Queues to work well with GSO :
	136	* The callback to TCP stack will be called at the time last frag
	137	* is freed at TX completion, and not right now when gso_skb
	138	* is freed by GSO engine
	139	*/
	140	if (copy_destructor) {
	141	swap(gso_skb->sk, skb->sk);
	142	swap(gso_skb->destructor, skb->destructor);
0d08c42c ED	143	sum_truesize += skb->truesize;
	144	atomic_add(sum_truesize - gso_skb->truesize,
	145	&skb->sk->sk_wmem_alloc);
28850dc7 DB	146	}
	147
	148	delta = htonl(oldlen + (skb_tail_pointer(skb) -
	149	skb_transport_header(skb)) +
	150	skb->data_len);
	151	th->check = ~csum_fold((__force __wsum)((__force u32)th->check +
	152	(__force u32)delta));
	153	if (skb->ip_summed != CHECKSUM_PARTIAL)
e9c3a24b	154	th->check = gso_make_checksum(skb, ~th->check);
28850dc7 DB	155	out:
	156	return segs;
	157	}
28850dc7 DB	158
	159	struct sk_buff tcp_gro_receive(struct sk_buff head, struct sk_buff *skb)
	160	{
	161	struct sk_buff **pp = NULL;
	162	struct sk_buff *p;
	163	struct tcphdr *th;
	164	struct tcphdr *th2;
	165	unsigned int len;
	166	unsigned int thlen;
	167	__be32 flags;
	168	unsigned int mss = 1;
	169	unsigned int hlen;
	170	unsigned int off;
	171	int flush = 1;
	172	int i;
	173
	174	off = skb_gro_offset(skb);
	175	hlen = off + sizeof(*th);
	176	th = skb_gro_header_fast(skb, off);
	177	if (skb_gro_header_hard(skb, hlen)) {
	178	th = skb_gro_header_slow(skb, hlen, off);
	179	if (unlikely(!th))
	180	goto out;
	181	}
	182
	183	thlen = th->doff * 4;
	184	if (thlen < sizeof(*th))
	185	goto out;
	186
	187	hlen = off + thlen;
	188	if (skb_gro_header_hard(skb, hlen)) {
	189	th = skb_gro_header_slow(skb, hlen, off);
	190	if (unlikely(!th))
	191	goto out;
	192	}
	193
	194	skb_gro_pull(skb, thlen);
	195
	196	len = skb_gro_len(skb);
	197	flags = tcp_flag_word(th);
	198
	199	for (; (p = *head); head = &p->next) {
	200	if (!NAPI_GRO_CB(p)->same_flow)
	201	continue;
	202
	203	th2 = tcp_hdr(p);
	204
	205	if ((u32 )&th->source ^ (u32 )&th2->source) {
	206	NAPI_GRO_CB(p)->same_flow = 0;
	207	continue;
	208	}
	209
	210	goto found;
	211	}
	212
	213	goto out_check_final;
	214
	215	found:
bf5a755f JC	216	/* Include the IP ID check below from the inner most IP hdr */
bf5a755f JC	217	flush = NAPI_GRO_CB(p)->flush \| NAPI_GRO_CB(p)->flush_id;
28850dc7 DB	218	flush \|= (__force int)(flags & TCP_FLAG_CWR);
	219	flush \|= (__force int)((flags ^ tcp_flag_word(th2)) &
	220	~(TCP_FLAG_CWR \| TCP_FLAG_FIN \| TCP_FLAG_PSH));
	221	flush \|= (__force int)(th->ack_seq ^ th2->ack_seq);
	222	for (i = sizeof(*th); i < thlen; i += 4)
	223	flush \|= (u32 )((u8 *)th + i) ^
	224	(u32 )((u8 *)th2 + i);
	225
	226	mss = tcp_skb_mss(p);
	227
	228	flush \|= (len - 1) >= mss;
	229	flush \|= (ntohl(th2->seq) + skb_gro_len(p)) ^ ntohl(th->seq);
	230
	231	if (flush \|\| skb_gro_receive(head, skb)) {
	232	mss = 1;
	233	goto out_check_final;
	234	}
	235
	236	p = *head;
	237	th2 = tcp_hdr(p);
	238	tcp_flag_word(th2) \|= flags & (TCP_FLAG_FIN \| TCP_FLAG_PSH);
	239
	240	out_check_final:
	241	flush = len < mss;
	242	flush \|= (__force int)(flags & (TCP_FLAG_URG \| TCP_FLAG_PSH \|
	243	TCP_FLAG_RST \| TCP_FLAG_SYN \|
	244	TCP_FLAG_FIN));
	245
	246	if (p && (!NAPI_GRO_CB(skb)->same_flow \|\| flush))
	247	pp = head;
	248
	249	out:
bf5a755f	250	NAPI_GRO_CB(skb)->flush \|= (flush != 0);
28850dc7 DB	251
	252	return pp;
	253	}
28850dc7 DB	254
	255	int tcp_gro_complete(struct sk_buff *skb)
	256	{
	257	struct tcphdr *th = tcp_hdr(skb);
	258
299603e8	259	skb->csum_start = (unsigned char *)th - skb->head;
28850dc7 DB	260	skb->csum_offset = offsetof(struct tcphdr, check);
	261	skb->ip_summed = CHECKSUM_PARTIAL;
	262
	263	skb_shinfo(skb)->gso_segs = NAPI_GRO_CB(skb)->count;
	264
	265	if (th->cwr)
	266	skb_shinfo(skb)->gso_type \|= SKB_GSO_TCP_ECN;
	267
	268	return 0;
	269	}
	270	EXPORT_SYMBOL(tcp_gro_complete);
	271
	272	static int tcp_v4_gso_send_check(struct sk_buff *skb)
	273	{
	274	const struct iphdr *iph;
	275	struct tcphdr *th;
	276
	277	if (!pskb_may_pull(skb, sizeof(*th)))
	278	return -EINVAL;
	279
	280	iph = ip_hdr(skb);
	281	th = tcp_hdr(skb);
	282
	283	th->check = 0;
	284	skb->ip_summed = CHECKSUM_PARTIAL;
	285	__tcp_v4_send_check(skb, iph->saddr, iph->daddr);
	286	return 0;
	287	}
	288
	289	static struct sk_buff tcp4_gro_receive(struct sk_buff head, struct sk_buff *skb)
	290	{
299603e8	291	/* Use the IP hdr immediately proceeding for this transport */
28850dc7 DB	292	const struct iphdr *iph = skb_gro_network_header(skb);
28850dc7 DB	293	__wsum wsum;
28850dc7	294
cc5c00bb HX	295	/* Don't bother verifying checksum if we're going to flush anyway. */
	296	if (NAPI_GRO_CB(skb)->flush)
	297	goto skip_csum;
	298
bf5a755f	299	wsum = NAPI_GRO_CB(skb)->csum;
b8ee93ba	300
28850dc7	301	switch (skb->ip_summed) {
b8ee93ba HX	302	case CHECKSUM_NONE:
	303	wsum = skb_checksum(skb, skb_gro_offset(skb), skb_gro_len(skb),
	304	0);
	305
	306	/* fall through */
	307
28850dc7 DB	308	case CHECKSUM_COMPLETE:
28850dc7 DB	309	if (!tcp_v4_check(skb_gro_len(skb), iph->saddr, iph->daddr,
b8ee93ba	310	wsum)) {
28850dc7 DB	311	skb->ip_summed = CHECKSUM_UNNECESSARY;
	312	break;
	313	}
b8ee93ba	314
28850dc7 DB	315	NAPI_GRO_CB(skb)->flush = 1;
28850dc7 DB	316	return NULL;
28850dc7 DB	317	}
28850dc7 DB	318
cc5c00bb	319	skip_csum:
28850dc7 DB	320	return tcp_gro_receive(head, skb);
	321	}
	322
299603e8	323	static int tcp4_gro_complete(struct sk_buff *skb, int thoff)
28850dc7 DB	324	{
	325	const struct iphdr *iph = ip_hdr(skb);
	326	struct tcphdr *th = tcp_hdr(skb);
	327
299603e8 JC	328	th->check = ~tcp_v4_check(skb->len - thoff, iph->saddr,
299603e8 JC	329	iph->daddr, 0);
c3caf119	330	skb_shinfo(skb)->gso_type \|= SKB_GSO_TCPV4;
28850dc7 DB	331
	332	return tcp_gro_complete(skb);
	333	}
	334
	335	static const struct net_offload tcpv4_offload = {
	336	.callbacks = {
	337	.gso_send_check = tcp_v4_gso_send_check,
28be6e07	338	.gso_segment = tcp_gso_segment,
28850dc7 DB	339	.gro_receive = tcp4_gro_receive,
	340	.gro_complete = tcp4_gro_complete,
	341	},
	342	};
	343
	344	int __init tcpv4_offload_init(void)
	345	{
	346	return inet_add_offload(&tcpv4_offload, IPPROTO_TCP);
	347	}