[SK_BUFF]: Introduce skb_network_header()

For the places where we need a pointer to the network header, it is still legal
to touch skb->nh.raw directly if just adding to, subtracting from or setting it
to another layer header.

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/ip_sockglue.c b/net/ipv4/ip_sockglue.c
index f8ab654..70888e1 100644
--- a/net/ipv4/ip_sockglue.c
+++ b/net/ipv4/ip_sockglue.c
@@ -273,7 +273,8 @@
 	serr->ee.ee_pad = 0;
 	serr->ee.ee_info = info;
 	serr->ee.ee_data = 0;
-	serr->addr_offset = (u8*)&(((struct iphdr*)(skb->h.icmph+1))->daddr) - skb->nh.raw;
+	serr->addr_offset = (u8 *)&(((struct iphdr *)(skb->h.icmph + 1))->daddr) -
+				   skb_network_header(skb);
 	serr->port = port;
 
 	skb->h.raw = payload;
@@ -309,7 +310,7 @@
 	serr->ee.ee_pad = 0;
 	serr->ee.ee_info = info;
 	serr->ee.ee_data = 0;
-	serr->addr_offset = (u8*)&iph->daddr - skb->nh.raw;
+	serr->addr_offset = (u8 *)&iph->daddr - skb_network_header(skb);
 	serr->port = port;
 
 	skb->h.raw = skb->tail;
@@ -355,7 +356,8 @@
 	sin = (struct sockaddr_in *)msg->msg_name;
 	if (sin) {
 		sin->sin_family = AF_INET;
-		sin->sin_addr.s_addr = *(__be32*)(skb->nh.raw + serr->addr_offset);
+		sin->sin_addr.s_addr = *(__be32 *)(skb_network_header(skb) +
+						   serr->addr_offset);
 		sin->sin_port = serr->port;
 		memset(&sin->sin_zero, 0, sizeof(sin->sin_zero));
 	}