[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/include/linux/skbuff.h b/include/linux/skbuff.h
index 43ab6cb..dff81af 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -960,6 +960,16 @@
 	skb->tail += len;
 }
 
+static inline unsigned char *skb_mac_header(const struct sk_buff *skb)
+{
+	return skb->mac.raw;
+}
+
+static inline int skb_mac_header_was_set(const struct sk_buff *skb)
+{
+	return skb->mac.raw != NULL;
+}
+
 static inline void skb_reset_mac_header(struct sk_buff *skb)
 {
 	skb->mac.raw = skb->data;