ipv6: Add new offload registration infrastructure.

Create a new data structure for IPv6 protocols that holds GRO/GSO
callbacks and a new array to track the protocols that register GRO/GSO.

Signed-off-by: Vlad Yasevich <vyasevic@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv6/protocol.c b/net/ipv6/protocol.c
index 053082d..f7c53a7 100644
--- a/net/ipv6/protocol.c
+++ b/net/ipv6/protocol.c
@@ -26,6 +26,7 @@
 #include <net/protocol.h>
 
 const struct inet6_protocol __rcu *inet6_protos[MAX_INET_PROTOS] __read_mostly;
+const struct net_offload __rcu *inet6_offloads[MAX_INET_PROTOS] __read_mostly;
 
 int inet6_add_protocol(const struct inet6_protocol *prot, unsigned char protocol)
 {
@@ -34,6 +35,13 @@
 }
 EXPORT_SYMBOL(inet6_add_protocol);
 
+int inet6_add_offload(const struct net_offload *prot, unsigned char protocol)
+{
+	return !cmpxchg((const struct net_offload **)&inet6_offloads[protocol],
+			NULL, prot) ? 0 : -1;
+}
+EXPORT_SYMBOL(inet6_add_offload);
+
 /*
  *	Remove a protocol from the hash tables.
  */
@@ -50,3 +58,16 @@
 	return ret;
 }
 EXPORT_SYMBOL(inet6_del_protocol);
+
+int inet6_del_offload(const struct net_offload *prot, unsigned char protocol)
+{
+	int ret;
+
+	ret = (cmpxchg((const struct net_offload **)&inet6_offloads[protocol],
+		       prot, NULL) == prot) ? 0 : -1;
+
+	synchronize_net();
+
+	return ret;
+}
+EXPORT_SYMBOL(inet6_del_offload);