[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/ipv6/ipv6_sockglue.c b/net/ipv6/ipv6_sockglue.c
index d16e0fd..da930fa 100644
--- a/net/ipv6/ipv6_sockglue.c
+++ b/net/ipv6/ipv6_sockglue.c
@@ -108,7 +108,7 @@
 	rcu_read_lock();
 	ops = ipv6_gso_pull_exthdrs(skb, ipv6h->nexthdr);
 	if (likely(ops && ops->gso_send_check)) {
-		skb->h.raw = skb->data;
+		skb_reset_transport_header(skb);
 		err = ops->gso_send_check(skb);
 	}
 	rcu_read_unlock();
@@ -144,7 +144,7 @@
 	rcu_read_lock();
 	ops = ipv6_gso_pull_exthdrs(skb, ipv6h->nexthdr);
 	if (likely(ops && ops->gso_segment)) {
-		skb->h.raw = skb->data;
+		skb_reset_transport_header(skb);
 		segs = ops->gso_segment(skb, features);
 	}
 	rcu_read_unlock();