[SK_BUFF]: Introduce ip_hdr(), remove skb->nh.iph

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/xfrm4_tunnel.c b/net/ipv4/xfrm4_tunnel.c
index 3eef064..5685103 100644
--- a/net/ipv4/xfrm4_tunnel.c
+++ b/net/ipv4/xfrm4_tunnel.c
@@ -12,9 +12,8 @@
 
 static int ipip_output(struct xfrm_state *x, struct sk_buff *skb)
 {
-	struct iphdr *iph;
+	struct iphdr *iph = ip_hdr(skb);
 
-	iph = skb->nh.iph;
 	iph->tot_len = htons(skb->len);
 	ip_send_check(iph);