netfilter: nf_ct_icmpv6: add icmpv6_kmemdup_sysctl_table function

Split sysctl function into smaller chucks to cleanup code and prepare
patches to reduce ifdef pollution.
Signed-off-by: NGao feng <gaofeng@cn.fujitsu.com>
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>

net/ipv6/netfilter/nf_conntrack_proto_icmpv6.c

@@ -333,22 +333,31 @@ static struct ctl_table icmpv6_sysctl_table[] = {
 };
 #endif /* CONFIG_SYSCTL */
 
-static int icmpv6_init_net(struct net *net, u_int16_t proto)
+static int icmpv6_kmemdup_sysctl_table(struct nf_proto_net *pn,
+				       struct nf_icmp_net *in)
 {
-	struct nf_icmp_net *in = icmpv6_pernet(net);
-	struct nf_proto_net *pn = (struct nf_proto_net *)in;
-	in->timeout = nf_ct_icmpv6_timeout;
 #ifdef CONFIG_SYSCTL
 	pn->ctl_table = kmemdup(icmpv6_sysctl_table,
 				sizeof(icmpv6_sysctl_table),
 				GFP_KERNEL);
 	if (!pn->ctl_table)
 		return -ENOMEM;
+
 	pn->ctl_table[0].data = &in->timeout;
 #endif
 	return 0;
 }
 
+static int icmpv6_init_net(struct net *net, u_int16_t proto)
+{
+	struct nf_icmp_net *in = icmpv6_pernet(net);
+	struct nf_proto_net *pn = &in->pn;
+
+	in->timeout = nf_ct_icmpv6_timeout;
+
+	return icmpv6_kmemdup_sysctl_table(pn, in);
+}
+
 struct nf_conntrack_l4proto nf_conntrack_l4proto_icmpv6 __read_mostly =
 {
 	.l3proto		= PF_INET6,