inet_hashtables: Add inet_lookup_skb helpers

To be able to use the cached socket reference in the skb during input
processing we add a new set of lookup functions that receive the skb on
their argument list.

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: KOVACS Krisztian <hidden@sch.bme.hu>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/dccp/ipv4.c b/net/dccp/ipv4.c
index 882c5c4..e3dfdda 100644
--- a/net/dccp/ipv4.c
+++ b/net/dccp/ipv4.c
@@ -811,9 +811,8 @@
 
 	/* Step 2:
 	 *	Look up flow ID in table and get corresponding socket */
-	sk = __inet_lookup(dev_net(skb->dst->dev), &dccp_hashinfo,
-			   iph->saddr, dh->dccph_sport,
-			   iph->daddr, dh->dccph_dport, inet_iif(skb));
+	sk = __inet_lookup_skb(&dccp_hashinfo, skb,
+			       dh->dccph_sport, dh->dccph_dport);
 	/*
 	 * Step 2:
 	 *	If no socket ...