diff mbox

[v2,net-next] net-gro: Prepare GRO stack for the upcoming tunneling support

Message ID 1386788641-16200-1-git-send-email-hkchu@google.com
State Changes Requested, archived
Delegated to: David Miller
Headers show

Commit Message

Jerry Chu Dec. 11, 2013, 7:04 p.m. UTC 
From: Jerry Chu <hkchu@google.com>

This patch modifies the GRO stack to avoid the use of "network_header"
and associated macros like ip_hdr() and ipv6_hdr() in order to allow
an arbitary number of IP hdrs (v4 or v6) to be used in the
encapsulation chain. This lays the foundation for various IP
tunneling support (IP-in-IP, GRE, VXLAN, SIT,...) to be added later.

With this patch, the GRO stack traversing now is mostly based on
skb_gro_offset rather than special hdr offsets saved in skb (e.g.,
skb->network_header). As a result all but the top layer (i.e., the
the transport layer) must have hdrs of the same length in order for
a pkt to be considered for aggregation. Therefore when adding a new
encap layer (e.g., for tunneling), one must check and skip flows
(e.g., by setting NAPI_GRO_CB(p)->same_flow to 0) that have a
different hdr length.

Note that unlike the network header, the transport header can and
will continue to be set by the GRO code since there will be at
most one "transport layer" in the encap chain.

Signed-off-by: H.K. Jerry Chu <hkchu@google.com>
Suggested-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
---
 include/linux/netdevice.h |  2 +-
 include/net/tcp.h         |  1 +
 net/core/dev.c            | 76 ++++++++++++++++-------------------------------
 net/ipv4/af_inet.c        | 26 +++++++++++-----
 net/ipv4/tcp_offload.c    | 28 ++++++++++-------
 net/ipv6/ip6_offload.c    | 64 +++++++++++++++++++++++++++++----------
 net/ipv6/tcpv6_offload.c  | 10 +++----
 7 files changed, 117 insertions(+), 90 deletions(-)

Comments

Eric Dumazet Dec. 11, 2013, 7:37 p.m. UTC | #1 
On Wed, 2013-12-11 at 11:04 -0800, H.K. Jerry Chu wrote:

> -int tcp_gro_complete(struct sk_buff *skb)
> +int __tcp_gro_complete(struct sk_buff *skb, struct tcphdr *th)
>  {
> -	struct tcphdr *th = tcp_hdr(skb);
> -
> -	skb->csum_start = skb_transport_header(skb) - skb->head;
> +	skb->csum_start = (unsigned char *)th - skb->head;
>  	skb->csum_offset = offsetof(struct tcphdr, check);
>  	skb->ip_summed = CHECKSUM_PARTIAL;
>  
> @@ -251,6 +250,12 @@ int tcp_gro_complete(struct sk_buff *skb)
>  
>  	return 0;
>  }
> +EXPORT_SYMBOL(__tcp_gro_complete);
> +
> +int tcp_gro_complete(struct sk_buff *skb)
> +{
> +	return __tcp_gro_complete(skb,  tcp_hdr(skb));
> +}


I have no idea why you kept this change.

As we said, the transport offset is set, so it looks like a lot of your
changes can be removed to ease the review

tcp_gro_receive() sets the transport header, so the xxx_complete()
handlers can rely on it.

The only part that you could keep is the following optim :

- skb->csum_start = skb_transport_header(skb) - skb->head;
+ skb->csum_start = (unsigned char *)th - skb->head;



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Jerry Chu Dec. 12, 2013, 3:45 a.m. UTC | #2 
On Thu, Dec 12, 2013 at 3:37 AM, Eric Dumazet <eric.dumazet@gmail.com> wrote:
> On Wed, 2013-12-11 at 11:04 -0800, H.K. Jerry Chu wrote:
>
>> -int tcp_gro_complete(struct sk_buff *skb)
>> +int __tcp_gro_complete(struct sk_buff *skb, struct tcphdr *th)
>>  {
>> -     struct tcphdr *th = tcp_hdr(skb);
>> -
>> -     skb->csum_start = skb_transport_header(skb) - skb->head;
>> +     skb->csum_start = (unsigned char *)th - skb->head;
>>       skb->csum_offset = offsetof(struct tcphdr, check);
>>       skb->ip_summed = CHECKSUM_PARTIAL;
>>
>> @@ -251,6 +250,12 @@ int tcp_gro_complete(struct sk_buff *skb)
>>
>>       return 0;
>>  }
>> +EXPORT_SYMBOL(__tcp_gro_complete);
>> +
>> +int tcp_gro_complete(struct sk_buff *skb)
>> +{
>> +     return __tcp_gro_complete(skb,  tcp_hdr(skb));
>> +}
>
>
> I have no idea why you kept this change.
>
> As we said, the transport offset is set, so it looks like a lot of your
> changes can be removed to ease the review

Yes I know but you were the one who suggested not setting the
transport header a while back, and seemed to prefer avoiding the use
of saved headers in skb.

Then you discovered the transport header must be set by the GRO
stack. That leaves the question should I still try to avoid using headers
saved in skb in case you may attempt to get rid of all the header setting
in GRO completely in the future. I decided last night to use the new
way (nhoff). But obviously the other way (to simply use
skb_transport_header to the extent possible) can be easily done and
will avoid much of the code change too. I'll send out v3 soon.

>
> tcp_gro_receive() sets the transport header, so the xxx_complete()
> handlers can rely on it.
>
> The only part that you could keep is the following optim :
>
> - skb->csum_start = skb_transport_header(skb) - skb->head;
> + skb->csum_start = (unsigned char *)th - skb->head;
>
>
>
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diff mbox

Patch

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 9d55e51..ba321f1b 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -1673,7 +1673,7 @@  struct offload_callbacks {
 	int			(*gso_send_check)(struct sk_buff *skb);
 	struct sk_buff		**(*gro_receive)(struct sk_buff **head,
 					       struct sk_buff *skb);
-	int			(*gro_complete)(struct sk_buff *skb);
+	int			(*gro_complete)(struct sk_buff *skb, int nhoff);
 };
 
 struct packet_offload {
diff --git a/include/net/tcp.h b/include/net/tcp.h
index f7e1ab2..bcd73ff 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -1549,6 +1549,7 @@  void tcp_v4_destroy_sock(struct sock *sk);
 struct sk_buff *tcp_gso_segment(struct sk_buff *skb,
 				netdev_features_t features);
 struct sk_buff **tcp_gro_receive(struct sk_buff **head, struct sk_buff *skb);
+int __tcp_gro_complete(struct sk_buff *skb, struct tcphdr *th);
 int tcp_gro_complete(struct sk_buff *skb);
 
 void __tcp_v4_send_check(struct sk_buff *skb, __be32 saddr, __be32 daddr);
diff --git a/net/core/dev.c b/net/core/dev.c
index 6cc98dd..bd71bec 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -3767,7 +3767,7 @@  static int napi_gro_complete(struct sk_buff *skb)
 		if (ptype->type != type || !ptype->callbacks.gro_complete)
 			continue;
 
-		err = ptype->callbacks.gro_complete(skb);
+		err = ptype->callbacks.gro_complete(skb, 0);
 		break;
 	}
 	rcu_read_unlock();
@@ -3833,6 +3833,23 @@  static void gro_list_prepare(struct napi_struct *napi, struct sk_buff *skb)
 	}
 }
 
+static void skb_gro_reset_offset(struct sk_buff *skb)
+{
+	const struct skb_shared_info *pinfo = skb_shinfo(skb);
+	const skb_frag_t *frag0 = &pinfo->frags[0];
+
+	NAPI_GRO_CB(skb)->data_offset = 0;
+	NAPI_GRO_CB(skb)->frag0 = NULL;
+	NAPI_GRO_CB(skb)->frag0_len = 0;
+
+	if (skb_mac_header(skb) == skb_tail_pointer(skb) &&
+	    pinfo->nr_frags &&
+	    !PageHighMem(skb_frag_page(frag0))) {
+		NAPI_GRO_CB(skb)->frag0 = skb_frag_address(frag0);
+		NAPI_GRO_CB(skb)->frag0_len = skb_frag_size(frag0);
+	}
+}
+
 static enum gro_result dev_gro_receive(struct napi_struct *napi, struct sk_buff *skb)
 {
 	struct sk_buff **pp = NULL;
@@ -3848,6 +3865,7 @@  static enum gro_result dev_gro_receive(struct napi_struct *napi, struct sk_buff
 	if (skb_is_gso(skb) || skb_has_frag_list(skb))
 		goto normal;
 
+	skb_gro_reset_offset(skb);
 	gro_list_prepare(napi, skb);
 
 	rcu_read_lock();
@@ -3953,27 +3971,8 @@  static gro_result_t napi_skb_finish(gro_result_t ret, struct sk_buff *skb)
 	return ret;
 }
 
-static void skb_gro_reset_offset(struct sk_buff *skb)
-{
-	const struct skb_shared_info *pinfo = skb_shinfo(skb);
-	const skb_frag_t *frag0 = &pinfo->frags[0];
-
-	NAPI_GRO_CB(skb)->data_offset = 0;
-	NAPI_GRO_CB(skb)->frag0 = NULL;
-	NAPI_GRO_CB(skb)->frag0_len = 0;
-
-	if (skb_mac_header(skb) == skb_tail_pointer(skb) &&
-	    pinfo->nr_frags &&
-	    !PageHighMem(skb_frag_page(frag0))) {
-		NAPI_GRO_CB(skb)->frag0 = skb_frag_address(frag0);
-		NAPI_GRO_CB(skb)->frag0_len = skb_frag_size(frag0);
-	}
-}
-
 gro_result_t napi_gro_receive(struct napi_struct *napi, struct sk_buff *skb)
 {
-	skb_gro_reset_offset(skb);
-
 	return napi_skb_finish(dev_gro_receive(napi, skb), skb);
 }
 EXPORT_SYMBOL(napi_gro_receive);
@@ -4007,12 +4006,7 @@  static gro_result_t napi_frags_finish(struct napi_struct *napi, struct sk_buff *
 {
 	switch (ret) {
 	case GRO_NORMAL:
-	case GRO_HELD:
-		skb->protocol = eth_type_trans(skb, skb->dev);
-
-		if (ret == GRO_HELD)
-			skb_gro_pull(skb, -ETH_HLEN);
-		else if (netif_receive_skb(skb))
+		if (netif_receive_skb(skb))
 			ret = GRO_DROP;
 		break;
 
@@ -4021,6 +4015,7 @@  static gro_result_t napi_frags_finish(struct napi_struct *napi, struct sk_buff *
 		napi_reuse_skb(napi, skb);
 		break;
 
+	case GRO_HELD:
 	case GRO_MERGED:
 		break;
 	}
@@ -4031,36 +4026,15 @@  static gro_result_t napi_frags_finish(struct napi_struct *napi, struct sk_buff *
 static struct sk_buff *napi_frags_skb(struct napi_struct *napi)
 {
 	struct sk_buff *skb = napi->skb;
-	struct ethhdr *eth;
-	unsigned int hlen;
-	unsigned int off;
 
 	napi->skb = NULL;
 
-	skb_reset_mac_header(skb);
-	skb_gro_reset_offset(skb);
-
-	off = skb_gro_offset(skb);
-	hlen = off + sizeof(*eth);
-	eth = skb_gro_header_fast(skb, off);
-	if (skb_gro_header_hard(skb, hlen)) {
-		eth = skb_gro_header_slow(skb, hlen, off);
-		if (unlikely(!eth)) {
-			napi_reuse_skb(napi, skb);
-			skb = NULL;
-			goto out;
-		}
+	if (unlikely(!pskb_may_pull(skb, sizeof(struct ethhdr)))) {
+		napi_reuse_skb(napi, skb);
+		return NULL;
 	}
+	skb->protocol = eth_type_trans(skb, skb->dev);
 
-	skb_gro_pull(skb, sizeof(*eth));
-
-	/*
-	 * This works because the only protocols we care about don't require
-	 * special handling.  We'll fix it up properly at the end.
-	 */
-	skb->protocol = eth->h_proto;
-
-out:
 	return skb;
 }
 
diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c
index 70011e0..cb406e9 100644
--- a/net/ipv4/af_inet.c
+++ b/net/ipv4/af_inet.c
@@ -1377,8 +1377,12 @@  static struct sk_buff **inet_gro_receive(struct sk_buff **head,
 		if (!NAPI_GRO_CB(p)->same_flow)
 			continue;
 
-		iph2 = ip_hdr(p);
-
+		iph2 = (struct iphdr *)(p->data + off);
+		/* The above works because, with the exception of the top
+		 * (inner most) layer, we only aggregate pkts with the same
+		 * hdr length so all the hdrs we'll need to verify will start
+		 * at the same offset.
+		 */
 		if ((iph->protocol ^ iph2->protocol) |
 		    ((__force u32)iph->saddr ^ (__force u32)iph2->saddr) |
 		    ((__force u32)iph->daddr ^ (__force u32)iph2->daddr)) {
@@ -1397,8 +1401,12 @@  static struct sk_buff **inet_gro_receive(struct sk_buff **head,
 	}
 
 	NAPI_GRO_CB(skb)->flush |= flush;
+	skb_set_network_header(skb, off);
+	/* The above will be needed by the transport layer if there is one
+	 * immediately following this IP hdr.
+	 */
+
 	skb_gro_pull(skb, sizeof(*iph));
-	skb_set_transport_header(skb, skb_gro_offset(skb));
 
 	pp = ops->callbacks.gro_receive(head, skb);
 
@@ -1411,10 +1419,10 @@  out:
 	return pp;
 }
 
-static int inet_gro_complete(struct sk_buff *skb)
+static int inet_gro_complete(struct sk_buff *skb, int nhoff)
 {
-	__be16 newlen = htons(skb->len - skb_network_offset(skb));
-	struct iphdr *iph = ip_hdr(skb);
+	__be16 newlen = htons(skb->len - nhoff);
+	struct iphdr *iph = (struct iphdr *)(skb->data + nhoff);
 	const struct net_offload *ops;
 	int proto = iph->protocol;
 	int err = -ENOSYS;
@@ -1427,7 +1435,11 @@  static int inet_gro_complete(struct sk_buff *skb)
 	if (WARN_ON(!ops || !ops->callbacks.gro_complete))
 		goto out_unlock;
 
-	err = ops->callbacks.gro_complete(skb);
+	/* Only need to add sizeof(*iph) to get to the next hdr below
+	 * because any hdr with option will have been flushed in
+	 * inet_gro_receive().
+	 */
+	err = ops->callbacks.gro_complete(skb, nhoff + sizeof(*iph));
 
 out_unlock:
 	rcu_read_unlock();
diff --git a/net/ipv4/tcp_offload.c b/net/ipv4/tcp_offload.c
index 0560635..c67bb45 100644
--- a/net/ipv4/tcp_offload.c
+++ b/net/ipv4/tcp_offload.c
@@ -175,6 +175,7 @@  struct sk_buff **tcp_gro_receive(struct sk_buff **head, struct sk_buff *skb)
 			goto out;
 	}
 
+	skb_set_transport_header(skb, off);
 	skb_gro_pull(skb, thlen);
 
 	len = skb_gro_len(skb);
@@ -184,7 +185,7 @@  struct sk_buff **tcp_gro_receive(struct sk_buff **head, struct sk_buff *skb)
 		if (!NAPI_GRO_CB(p)->same_flow)
 			continue;
 
-		th2 = tcp_hdr(p);
+		th2 = (struct tcphdr *)(p->data + off);
 
 		if (*(u32 *)&th->source ^ *(u32 *)&th2->source) {
 			NAPI_GRO_CB(p)->same_flow = 0;
@@ -217,7 +218,7 @@  found:
 	}
 
 	p = *head;
-	th2 = tcp_hdr(p);
+	th2 = (struct tcphdr *)(p->data + off);
 	tcp_flag_word(th2) |= flags & (TCP_FLAG_FIN | TCP_FLAG_PSH);
 
 out_check_final:
@@ -236,11 +237,9 @@  out:
 }
 EXPORT_SYMBOL(tcp_gro_receive);
 
-int tcp_gro_complete(struct sk_buff *skb)
+int __tcp_gro_complete(struct sk_buff *skb, struct tcphdr *th)
 {
-	struct tcphdr *th = tcp_hdr(skb);
-
-	skb->csum_start = skb_transport_header(skb) - skb->head;
+	skb->csum_start = (unsigned char *)th - skb->head;
 	skb->csum_offset = offsetof(struct tcphdr, check);
 	skb->ip_summed = CHECKSUM_PARTIAL;
 
@@ -251,6 +250,12 @@  int tcp_gro_complete(struct sk_buff *skb)
 
 	return 0;
 }
+EXPORT_SYMBOL(__tcp_gro_complete);
+
+int tcp_gro_complete(struct sk_buff *skb)
+{
+	return __tcp_gro_complete(skb,  tcp_hdr(skb));
+}
 EXPORT_SYMBOL(tcp_gro_complete);
 
 static int tcp_v4_gso_send_check(struct sk_buff *skb)
@@ -272,6 +277,7 @@  static int tcp_v4_gso_send_check(struct sk_buff *skb)
 
 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;
 
@@ -303,16 +309,16 @@  skip_csum:
 	return tcp_gro_receive(head, skb);
 }
 
-static int tcp4_gro_complete(struct sk_buff *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);
+	struct tcphdr *th = (struct tcphdr *)(skb->data + thoff);
 
-	th->check = ~tcp_v4_check(skb->len - skb_transport_offset(skb),
-				  iph->saddr, iph->daddr, 0);
+	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);
+	return __tcp_gro_complete(skb, th);
 }
 
 static const struct net_offload tcpv4_offload = {
diff --git a/net/ipv6/ip6_offload.c b/net/ipv6/ip6_offload.c
index 4b85169..448d238 100644
--- a/net/ipv6/ip6_offload.c
+++ b/net/ipv6/ip6_offload.c
@@ -154,6 +154,35 @@  out:
 	return segs;
 }
 
+/* Return the total length of all the extension hdrs, following the same
+ * logic in ipv6_gso_pull_exthdrs() when parsing ext-hdrs.
+ */
+static int ipv6_exthdrs_len(struct ipv6hdr *iph,
+			    const struct net_offload **opps)
+{
+	struct ipv6_opt_hdr *opth = NULL;
+	int len = 0, proto, optlen;
+
+	proto = iph->nexthdr;
+	for (;;) {
+		if (proto != NEXTHDR_HOP) {
+			*opps = rcu_dereference(inet6_offloads[proto]);
+			if (unlikely(!(*opps)))
+				break;
+			if (!((*opps)->flags & INET6_PROTO_GSO_EXTHDR))
+				break;
+		}
+		if (opth == NULL)
+			opth = (void *)(iph+1);
+		else
+			opth = (void *)opth + optlen;
+		optlen = ipv6_optlen(opth);
+		len += optlen;
+		proto = opth->nexthdr;
+	}
+	return len;
+}
+
 static struct sk_buff **ipv6_gro_receive(struct sk_buff **head,
 					 struct sk_buff *skb)
 {
@@ -167,6 +196,7 @@  static struct sk_buff **ipv6_gro_receive(struct sk_buff **head,
 	int flush = 1;
 	int proto;
 	__wsum csum;
+	__u16	next_header;
 
 	off = skb_gro_offset(skb);
 	hlen = off + sizeof(*iph);
@@ -176,9 +206,9 @@  static struct sk_buff **ipv6_gro_receive(struct sk_buff **head,
 		if (unlikely(!iph))
 			goto out;
 	}
-
+	skb_set_network_header(skb, off);
 	skb_gro_pull(skb, sizeof(*iph));
-	skb_set_transport_header(skb, skb_gro_offset(skb));
+	next_header = skb->data - skb->head + skb_gro_offset(skb);
 
 	flush += ntohs(iph->payload_len) != skb_gro_len(skb);
 
@@ -188,8 +218,8 @@  static struct sk_buff **ipv6_gro_receive(struct sk_buff **head,
 	if (!ops || !ops->callbacks.gro_receive) {
 		__pskb_pull(skb, skb_gro_offset(skb));
 		proto = ipv6_gso_pull_exthdrs(skb, proto);
-		skb_gro_pull(skb, -skb_transport_offset(skb));
-		skb_reset_transport_header(skb);
+		skb_gro_pull(skb, -(int)(skb->head + next_header - skb->data));
+		next_header = skb->data - skb->head;
 		__skb_push(skb, skb_gro_offset(skb));
 
 		ops = rcu_dereference(inet6_offloads[proto]);
@@ -202,7 +232,7 @@  static struct sk_buff **ipv6_gro_receive(struct sk_buff **head,
 	NAPI_GRO_CB(skb)->proto = proto;
 
 	flush--;
-	nlen = skb_network_header_len(skb);
+	nlen = next_header - skb->network_header;
 
 	for (p = *head; p; p = p->next) {
 		const struct ipv6hdr *iph2;
@@ -211,12 +241,16 @@  static struct sk_buff **ipv6_gro_receive(struct sk_buff **head,
 		if (!NAPI_GRO_CB(p)->same_flow)
 			continue;
 
-		iph2 = ipv6_hdr(p);
+		iph2 = (struct ipv6hdr *)(p->data + off);
 		first_word = *(__be32 *)iph ^ *(__be32 *)iph2 ;
 
-		/* All fields must match except length and Traffic Class. */
-		if (nlen != skb_network_header_len(p) ||
-		    (first_word & htonl(0xF00FFFFF)) ||
+		/* All fields must match except length and Traffic Class.
+		 * XXX skbs on the gro_list have all been parsed and pulled
+		 * already so we don't need to compare nlen
+		 * (nlen != (sizeof(*iph2) + ipv6_exthdrs_len(iph2, &ops)))
+		 * memcmp() alone below is suffcient, right?
+		 */
+		 if ((first_word & htonl(0xF00FFFFF)) ||
 		    memcmp(&iph->nexthdr, &iph2->nexthdr,
 			   nlen - offsetof(struct ipv6hdr, nexthdr))) {
 			NAPI_GRO_CB(p)->same_flow = 0;
@@ -245,21 +279,21 @@  out:
 	return pp;
 }
 
-static int ipv6_gro_complete(struct sk_buff *skb)
+static int ipv6_gro_complete(struct sk_buff *skb, int nhoff)
 {
 	const struct net_offload *ops;
-	struct ipv6hdr *iph = ipv6_hdr(skb);
+	struct ipv6hdr *iph = (struct ipv6hdr *)(skb->data + nhoff);
 	int err = -ENOSYS;
 
-	iph->payload_len = htons(skb->len - skb_network_offset(skb) -
-				 sizeof(*iph));
+	iph->payload_len = htons(skb->len - nhoff - sizeof(*iph));
 
 	rcu_read_lock();
-	ops = rcu_dereference(inet6_offloads[NAPI_GRO_CB(skb)->proto]);
+
+	nhoff += sizeof(*iph) + ipv6_exthdrs_len(iph, &ops);
 	if (WARN_ON(!ops || !ops->callbacks.gro_complete))
 		goto out_unlock;
 
-	err = ops->callbacks.gro_complete(skb);
+	err = ops->callbacks.gro_complete(skb, nhoff);
 
 out_unlock:
 	rcu_read_unlock();
diff --git a/net/ipv6/tcpv6_offload.c b/net/ipv6/tcpv6_offload.c
index 6d18157..7878ca2 100644
--- a/net/ipv6/tcpv6_offload.c
+++ b/net/ipv6/tcpv6_offload.c
@@ -66,16 +66,16 @@  skip_csum:
 	return tcp_gro_receive(head, skb);
 }
 
-static int tcp6_gro_complete(struct sk_buff *skb)
+static int tcp6_gro_complete(struct sk_buff *skb, int thoff)
 {
 	const struct ipv6hdr *iph = ipv6_hdr(skb);
-	struct tcphdr *th = tcp_hdr(skb);
+	struct tcphdr *th = (struct tcphdr *)(skb->data + thoff);
 
-	th->check = ~tcp_v6_check(skb->len - skb_transport_offset(skb),
-				  &iph->saddr, &iph->daddr, 0);
+	th->check = ~tcp_v6_check(skb->len - thoff, &iph->saddr,
+				  &iph->daddr, 0);
 	skb_shinfo(skb)->gso_type = SKB_GSO_TCPV6;
 
-	return tcp_gro_complete(skb);
+	return __tcp_gro_complete(skb, th);
 }
 
 static const struct net_offload tcpv6_offload = {