ip: factor out protocol delivery helper

So that we can re-use it at the UDP level in a later patch

rfc v3 -> v1
 - add the helper declaration into the ip header
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/ip.h

@@ -155,6 +155,7 @@ int ip_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *pt,
 void ip_list_rcv(struct list_head *head, struct packet_type *pt,
 		 struct net_device *orig_dev);
 int ip_local_deliver(struct sk_buff *skb);
+void ip_protocol_deliver_rcu(struct net *net, struct sk_buff *skb, int proto);
 int ip_mr_input(struct sk_buff *skb);
 int ip_output(struct net *net, struct sock *sk, struct sk_buff *skb);
 int ip_mc_output(struct net *net, struct sock *sk, struct sk_buff *skb);

net/ipv4/ip_input.c

@@ -188,27 +188,20 @@ bool ip_call_ra_chain(struct sk_buff *skb)
 	return false;
 }
 
-static int ip_local_deliver_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
+void ip_protocol_deliver_rcu(struct net *net, struct sk_buff *skb, int protocol)
 {
-	__skb_pull(skb, skb_network_header_len(skb));
-
-	rcu_read_lock();
-	{
-		int protocol = ip_hdr(skb)->protocol;
 	const struct net_protocol *ipprot;
-		int raw;
+	int raw, ret;
 
-	resubmit:
+resubmit:
 	raw = raw_local_deliver(skb, protocol);
 
 	ipprot = rcu_dereference(inet_protos[protocol]);
 	if (ipprot) {
-			int ret;
-
 		if (!ipprot->no_policy) {
 			if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
 				kfree_skb(skb);
-					goto out;
+				return;
 			}
 			nf_reset(skb);
 		}
@@ -231,8 +224,14 @@ static int ip_local_deliver_finish(struct net *net, struct sock *sk, struct sk_b
 			consume_skb(skb);
 		}
 	}
-	}
- out:
+}
+
+static int ip_local_deliver_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
+{
+	__skb_pull(skb, skb_network_header_len(skb));
+
+	rcu_read_lock();
+	ip_protocol_deliver_rcu(net, skb, ip_hdr(skb)->protocol);
 	rcu_read_unlock();
 
 	return 0;