netfilter: nf_conntrack: refactor l4proto support for netns

Move the code that register/unregister l4proto to the
module_init/exit context.

Given that we have to modify some interfaces to accomodate
these changes, it is a good time to use shorter function names
for this using the nf_ct_* prefix instead of nf_conntrack_*,
that is:

nf_ct_l4proto_register
nf_ct_l4proto_pernet_register
nf_ct_l4proto_unregister
nf_ct_l4proto_pernet_unregister

We same many line breaks with it.

Signed-off-by: Gao feng <gaofeng@cn.fujitsu.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
diff --git a/net/netfilter/nf_conntrack_proto_gre.c b/net/netfilter/nf_conntrack_proto_gre.c
index b09b7af..bd7d01d 100644
--- a/net/netfilter/nf_conntrack_proto_gre.c
+++ b/net/netfilter/nf_conntrack_proto_gre.c
@@ -397,15 +397,15 @@
 static int proto_gre_net_init(struct net *net)
 {
 	int ret = 0;
-	ret = nf_conntrack_l4proto_register(net, &nf_conntrack_l4proto_gre4);
+	ret = nf_ct_l4proto_pernet_register(net, &nf_conntrack_l4proto_gre4);
 	if (ret < 0)
-		pr_err("nf_conntrack_l4proto_gre4 :protocol register failed.\n");
+		pr_err("nf_conntrack_gre4: pernet registration failed.\n");
 	return ret;
 }
 
 static void proto_gre_net_exit(struct net *net)
 {
-	nf_conntrack_l4proto_unregister(net, &nf_conntrack_l4proto_gre4);
+	nf_ct_l4proto_pernet_unregister(net, &nf_conntrack_l4proto_gre4);
 	nf_ct_gre_keymap_flush(net);
 }
 
@@ -418,11 +418,26 @@
 
 static int __init nf_ct_proto_gre_init(void)
 {
-	return register_pernet_subsys(&proto_gre_net_ops);
+	int ret;
+
+	ret = nf_ct_l4proto_register(&nf_conntrack_l4proto_gre4);
+	if (ret < 0)
+		goto out_gre4;
+
+	ret = register_pernet_subsys(&proto_gre_net_ops);
+	if (ret < 0)
+		goto out_pernet;
+
+	return 0;
+out_pernet:
+	nf_ct_l4proto_unregister(&nf_conntrack_l4proto_gre4);
+out_gre4:
+	return ret;
 }
 
 static void __exit nf_ct_proto_gre_fini(void)
 {
+	nf_ct_l4proto_unregister(&nf_conntrack_l4proto_gre4);
 	unregister_pernet_subsys(&proto_gre_net_ops);
 }