[IPV6]: Added GSO support for TCPv6

This patch adds GSO support for IPv6 and TCPv6.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/protocol.h

@@ -50,11 +50,17 @@ struct inet6_protocol
 			       struct inet6_skb_parm *opt,
 			       int type, int code, int offset,
 			       __u32 info);
+
+	struct sk_buff *(*gso_segment)(struct sk_buff *skb,
+				       int features);
+
 	unsigned int	flags;	/* INET6_PROTO_xxx */
 };
 
 #define INET6_PROTO_NOPOLICY	0x1
 #define INET6_PROTO_FINAL	0x2
+/* This should be set for any extension header which is compatible with GSO. */
+#define INET6_PROTO_GSO_EXTHDR	0x4
 #endif
 
 /* This is used to register socket interfaces for IP protocols.  */

net/ipv4/tcp.c

@@ -2215,6 +2215,7 @@ struct sk_buff *tcp_tso_segment(struct sk_buff *skb, int features)
 out:
 	return segs;
 }
+EXPORT_SYMBOL(tcp_tso_segment);
 
 extern void __skb_cb_too_small_for_tcp(int, int);
 extern struct tcp_congestion_ops tcp_reno;

net/ipv6/exthdrs.c

@@ -179,7 +179,7 @@ static int ipv6_destopt_rcv(struct sk_buff **skbp)
 
 static struct inet6_protocol destopt_protocol = {
 	.handler	=	ipv6_destopt_rcv,
-	.flags		=	INET6_PROTO_NOPOLICY,
+	.flags		=	INET6_PROTO_NOPOLICY | INET6_PROTO_GSO_EXTHDR,
 };
 
 void __init ipv6_destopt_init(void)
@@ -340,7 +340,7 @@ static int ipv6_rthdr_rcv(struct sk_buff **skbp)
 
 static struct inet6_protocol rthdr_protocol = {
 	.handler	=	ipv6_rthdr_rcv,
-	.flags		=	INET6_PROTO_NOPOLICY,
+	.flags		=	INET6_PROTO_NOPOLICY | INET6_PROTO_GSO_EXTHDR,
 };
 
 void __init ipv6_rthdr_init(void)

net/ipv6/ipv6_sockglue.c

@@ -58,9 +58,71 @@
 
 DEFINE_SNMP_STAT(struct ipstats_mib, ipv6_statistics) __read_mostly;
 
+static struct sk_buff *ipv6_gso_segment(struct sk_buff *skb, int features)
+{
+	struct sk_buff *segs = ERR_PTR(-EINVAL);
+	struct ipv6hdr *ipv6h;
+	struct inet6_protocol *ops;
+	int proto;
+
+	if (unlikely(!pskb_may_pull(skb, sizeof(*ipv6h))))
+		goto out;
+
+	ipv6h = skb->nh.ipv6h;
+	proto = ipv6h->nexthdr;
+	__skb_pull(skb, sizeof(*ipv6h));
+
+	rcu_read_lock();
+	for (;;) {
+		struct ipv6_opt_hdr *opth;
+		int len;
+
+		if (proto != NEXTHDR_HOP) {
+			ops = rcu_dereference(inet6_protos[proto]);
+
+			if (unlikely(!ops))
+				goto unlock;
+
+			if (!(ops->flags & INET6_PROTO_GSO_EXTHDR))
+				break;
+		}
+
+		if (unlikely(!pskb_may_pull(skb, 8)))
+			goto unlock;
+
+		opth = (void *)skb->data;
+		len = opth->hdrlen * 8 + 8;
+
+		if (unlikely(!pskb_may_pull(skb, len)))
+			goto unlock;
+
+		proto = opth->nexthdr;
+		__skb_pull(skb, len);
+	}
+
+	skb->h.raw = skb->data;
+	if (likely(ops->gso_segment))
+		segs = ops->gso_segment(skb, features);
+
+unlock:
+	rcu_read_unlock();
+
+	if (unlikely(IS_ERR(segs)))
+		goto out;
+
+	for (skb = segs; skb; skb = skb->next) {
+		ipv6h = skb->nh.ipv6h;
+		ipv6h->payload_len = htons(skb->len - skb->mac_len);
+	}
+
+out:
+	return segs;
+}
+
 static struct packet_type ipv6_packet_type = {
 	.type = __constant_htons(ETH_P_IPV6), 
 	.func = ipv6_rcv,
+	.gso_segment = ipv6_gso_segment,
 };
 
 struct ip6_ra_chain *ip6_ra_chain;

net/ipv6/tcp_ipv6.c

@@ -1606,6 +1606,7 @@ struct proto tcpv6_prot = {
 static struct inet6_protocol tcpv6_protocol = {
 	.handler	=	tcp_v6_rcv,
 	.err_handler	=	tcp_v6_err,
+	.gso_segment	=	tcp_tso_segment,
 	.flags		=	INET6_PROTO_NOPOLICY|INET6_PROTO_FINAL,
 };