[SK_BUFF]: Introduce skb_reset_transport_header(skb)

For the common, open coded 'skb->h.raw = skb->data' operation, so that we can
later turn skb->h.raw into a offset, reducing the size of struct sk_buff in
64bit land while possibly keeping it as a pointer on 32bit.

This one touches just the most simple cases:

skb->h.raw = skb->data;
skb->h.raw = {skb_push|[__]skb_pull}()

The next ones will handle the slightly more "complex" cases.

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c
index e7720c7..f011390 100644
--- a/net/ipv4/af_inet.c
+++ b/net/ipv4/af_inet.c
@@ -1120,7 +1120,8 @@
 	if (unlikely(!pskb_may_pull(skb, ihl)))
 		goto out;
 
-	skb->h.raw = __skb_pull(skb, ihl);
+	__skb_pull(skb, ihl);
+	skb_reset_transport_header(skb);
 	iph = ip_hdr(skb);
 	proto = iph->protocol & (MAX_INET_PROTOS - 1);
 	err = -EPROTONOSUPPORT;
@@ -1163,7 +1164,8 @@
 	if (unlikely(!pskb_may_pull(skb, ihl)))
 		goto out;
 
-	skb->h.raw = __skb_pull(skb, ihl);
+	__skb_pull(skb, ihl);
+	skb_reset_transport_header(skb);
 	iph = ip_hdr(skb);
 	id = ntohs(iph->id);
 	proto = iph->protocol & (MAX_INET_PROTOS - 1);