[SK_BUFF]: Introduce skb_mac_header()

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

This one also converts some more cases to skb_reset_mac_header() that my
regex missed as it had no spaces before nor after '=', ugh.

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index 6f8c72d..73cb2d3 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -284,7 +284,7 @@
 	 *	Incoming packets have ll header pulled,
 	 *	push it back.
 	 *
-	 *	For outgoing ones skb->data == skb->mac.raw
+	 *	For outgoing ones skb->data == skb_mac_header(skb)
 	 *	so that this procedure is noop.
 	 */
 
@@ -303,7 +303,7 @@
 
 	spkt = &PACKET_SKB_CB(skb)->sa.pkt;
 
-	skb_push(skb, skb->data-skb->mac.raw);
+	skb_push(skb, skb->data - skb_mac_header(skb));
 
 	/*
 	 *	The SOCK_PACKET socket receives _all_ frames.
@@ -488,7 +488,7 @@
 		   never delivered to user.
 		 */
 		if (sk->sk_type != SOCK_DGRAM)
-			skb_push(skb, skb->data - skb->mac.raw);
+			skb_push(skb, skb->data - skb_mac_header(skb));
 		else if (skb->pkt_type == PACKET_OUTGOING) {
 			/* Special case: outgoing packets have ll header at head */
 			skb_pull(skb, skb->nh.raw - skb->data);
@@ -592,7 +592,7 @@
 
 	if (dev->hard_header) {
 		if (sk->sk_type != SOCK_DGRAM)
-			skb_push(skb, skb->data - skb->mac.raw);
+			skb_push(skb, skb->data - skb_mac_header(skb));
 		else if (skb->pkt_type == PACKET_OUTGOING) {
 			/* Special case: outgoing packets have ll header at head */
 			skb_pull(skb, skb->nh.raw - skb->data);