ip_tunnel: Ops registration for secondary encap (fou, gue)

Instead of calling fou and gue functions directly from ip_tunnel
use ops for these that were previously registered. This patch adds the
logic to add and remove encapsulation operations for ip_tunnel,
and modified fou (and gue) to register with ip_tunnels.

This patch also addresses a circular dependency between ip_tunnel
and fou that was causing link errors when CONFIG_NET_IP_TUNNEL=y
and CONFIG_NET_FOU=m. References to fou an gue have been removed from
ip_tunnel.c

Reported-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Tom Herbert <therbert@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 16 insertions, 0 deletions

diff --git a/include/net/ip_tunnels.h b/include/net/ip_tunnels.h
index 5bc6edeb7143..25a59eb388a6 100644
--- a/include/net/ip_tunnels.h
+++ b/include/net/ip_tunnels.h
@@ -117,6 +117,22 @@ struct ip_tunnel_net {
         struct hlist_head tunnels[IP_TNL_HASH_SIZE];
 };
 
+struct ip_tunnel_encap_ops {
+        size_t (*encap_hlen)(struct ip_tunnel_encap *e);
+        int (*build_header)(struct sk_buff *skb, struct ip_tunnel_encap *e,
+                            u8 *protocol, struct flowi4 *fl4);
+};
+
+#define MAX_IPTUN_ENCAP_OPS 8
+
+extern const struct ip_tunnel_encap_ops __rcu *
+                iptun_encaps[MAX_IPTUN_ENCAP_OPS];
+
+int ip_tunnel_encap_add_ops(const struct ip_tunnel_encap_ops *op,
+                            unsigned int num);
+int ip_tunnel_encap_del_ops(const struct ip_tunnel_encap_ops *op,
+                            unsigned int num);
+
 #ifdef CONFIG_INET
 
 int ip_tunnel_init(struct net_device *dev);