netfilter: conntrack: remove unused init_net hook

since adf05168 ("netfilter: remove ip_conntrack* sysctl compat code")
the only user (ipv4 tracker) sets this to an empty stub function.

After this change nf_ct_l3proto_pernet_register() is also empty,
but this will change in a followup patch to add conditional register
of the hooks.
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

include/net/netfilter/nf_conntrack_l3proto.h

@@ -63,9 +63,6 @@ struct nf_conntrack_l3proto {
 
 	size_t nla_size;
 
-	/* Init l3proto pernet data */
-	int (*init_net)(struct net *net);
-
 	/* Module (if any) which this is connected to. */
 	struct module *me;
 };

net/ipv4/netfilter/nf_conntrack_l3proto_ipv4.c

@@ -307,11 +307,6 @@ static struct nf_sockopt_ops so_getorigdst = {
 	.owner		= THIS_MODULE,
 };
 
-static int ipv4_init_net(struct net *net)
-{
-	return 0;
-}
-
 struct nf_conntrack_l3proto nf_conntrack_l3proto_ipv4 __read_mostly = {
 	.l3proto	 = PF_INET,
 	.name		 = "ipv4",
@@ -325,7 +320,6 @@ struct nf_conntrack_l3proto nf_conntrack_l3proto_ipv4 __read_mostly = {
 	.nlattr_to_tuple = ipv4_nlattr_to_tuple,
 	.nla_policy	 = ipv4_nla_policy,
 #endif
-	.init_net	 = ipv4_init_net,
 	.me		 = THIS_MODULE,
 };
 

net/netfilter/nf_conntrack_proto.c

@@ -193,14 +193,6 @@ EXPORT_SYMBOL_GPL(nf_ct_l3proto_register);
 int nf_ct_l3proto_pernet_register(struct net *net,
 				  struct nf_conntrack_l3proto *proto)
 {
-	int ret;
-
-	if (proto->init_net) {
-		ret = proto->init_net(net);
-		if (ret < 0)
-			return ret;
-	}
-
 	return 0;
 }
 EXPORT_SYMBOL_GPL(nf_ct_l3proto_pernet_register);