tcp6: Add GRO support

This patch adds GRO support for TCP over IPv6.  The code is exactly
the same as the IPv4 version except for the pseudo-header checksum
computation.

Note that I've removed the unused tcphdr argument from tcp_v6_check
rather than invent a bogus value for GRO.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv4/tcp.c

@@ -2542,6 +2542,7 @@ struct sk_buff **tcp_gro_receive(struct sk_buff **head, struct sk_buff *skb)
 
 	return pp;
 }
+EXPORT_SYMBOL(tcp_gro_receive);
 
 int tcp_gro_complete(struct sk_buff *skb)
 {
@@ -2558,6 +2559,7 @@ int tcp_gro_complete(struct sk_buff *skb)
 
 	return 0;
 }
+EXPORT_SYMBOL(tcp_gro_complete);
 
 #ifdef CONFIG_TCP_MD5SIG
 static unsigned long tcp_md5sig_users;

net/ipv6/tcp_ipv6.c

@@ -101,7 +101,7 @@ static void tcp_v6_hash(struct sock *sk)
 	}
 }
 
-static __inline__ __sum16 tcp_v6_check(struct tcphdr *th, int len,
+static __inline__ __sum16 tcp_v6_check(int len,
 				   struct in6_addr *saddr,
 				   struct in6_addr *daddr,
 				   __wsum base)
@@ -501,7 +501,7 @@ static int tcp_v6_send_synack(struct sock *sk, struct request_sock *req)
 	if (skb) {
 		struct tcphdr *th = tcp_hdr(skb);
 
-		th->check = tcp_v6_check(th, skb->len,
+		th->check = tcp_v6_check(skb->len,
 					 &treq->loc_addr, &treq->rmt_addr,
 					 csum_partial(th, skb->len, skb->csum));
 
@@ -942,6 +942,41 @@ static int tcp_v6_gso_send_check(struct sk_buff *skb)
 	return 0;
 }
 
+struct sk_buff **tcp6_gro_receive(struct sk_buff **head, struct sk_buff *skb)
+{
+	struct ipv6hdr *iph = ipv6_hdr(skb);
+
+	switch (skb->ip_summed) {
+	case CHECKSUM_COMPLETE:
+		if (!tcp_v6_check(skb->len, &iph->saddr, &iph->daddr,
+				  skb->csum)) {
+			skb->ip_summed = CHECKSUM_UNNECESSARY;
+			break;
+		}
+
+		/* fall through */
+	case CHECKSUM_NONE:
+		NAPI_GRO_CB(skb)->flush = 1;
+		return NULL;
+	}
+
+	return tcp_gro_receive(head, skb);
+}
+EXPORT_SYMBOL(tcp6_gro_receive);
+
+int tcp6_gro_complete(struct sk_buff *skb)
+{
+	struct ipv6hdr *iph = ipv6_hdr(skb);
+	struct tcphdr *th = tcp_hdr(skb);
+
+	th->check = ~tcp_v6_check(skb->len - skb_transport_offset(skb),
+				  &iph->saddr, &iph->daddr, 0);
+	skb_shinfo(skb)->gso_type = SKB_GSO_TCPV6;
+
+	return tcp_gro_complete(skb);
+}
+EXPORT_SYMBOL(tcp6_gro_complete);
+
 static void tcp_v6_send_response(struct sk_buff *skb, u32 seq, u32 ack, u32 win,
 				 u32 ts, struct tcp_md5sig_key *key, int rst)
 {
@@ -1429,14 +1464,14 @@ static struct sock * tcp_v6_syn_recv_sock(struct sock *sk, struct sk_buff *skb,
 static __sum16 tcp_v6_checksum_init(struct sk_buff *skb)
 {
 	if (skb->ip_summed == CHECKSUM_COMPLETE) {
-		if (!tcp_v6_check(tcp_hdr(skb), skb->len, &ipv6_hdr(skb)->saddr,
+		if (!tcp_v6_check(skb->len, &ipv6_hdr(skb)->saddr,
 				  &ipv6_hdr(skb)->daddr, skb->csum)) {
 			skb->ip_summed = CHECKSUM_UNNECESSARY;
 			return 0;
 		}
 	}
 
-	skb->csum = ~csum_unfold(tcp_v6_check(tcp_hdr(skb), skb->len,
+	skb->csum = ~csum_unfold(tcp_v6_check(skb->len,
 					      &ipv6_hdr(skb)->saddr,
 					      &ipv6_hdr(skb)->daddr, 0));
 
@@ -2062,6 +2097,8 @@ static struct inet6_protocol tcpv6_protocol = {
 	.err_handler	=	tcp_v6_err,
 	.gso_send_check	=	tcp_v6_gso_send_check,
 	.gso_segment	=	tcp_tso_segment,
+	.gro_receive	=	tcp6_gro_receive,
+	.gro_complete	=	tcp6_gro_complete,
 	.flags		=	INET6_PROTO_NOPOLICY|INET6_PROTO_FINAL,
 };