[SK_BUFF]: Introduce skb_transport_offset()

For the quite common 'skb->h.raw - skb->data' sequence.

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/e1000/e1000_main.c b/drivers/net/e1000/e1000_main.c
index a3d9986..78cf417 100644
--- a/drivers/net/e1000/e1000_main.c
+++ b/drivers/net/e1000/e1000_main.c
@@ -2887,7 +2887,7 @@
 				return err;
 		}
 
-		hdr_len = ((skb->h.raw - skb->data) + (skb->h.th->doff << 2));
+		hdr_len = (skb_transport_offset(skb) + (skb->h.th->doff << 2));
 		mss = skb_shinfo(skb)->gso_size;
 		if (skb->protocol == htons(ETH_P_IP)) {
 			struct iphdr *iph = ip_hdr(skb);
@@ -2897,7 +2897,7 @@
 							      iph->daddr, 0,
 							      IPPROTO_TCP, 0);
 			cmd_length = E1000_TXD_CMD_IP;
-			ipcse = skb->h.raw - skb->data - 1;
+			ipcse = skb_transport_offset(skb) - 1;
 		} else if (skb->protocol == htons(ETH_P_IPV6)) {
 			ipv6_hdr(skb)->payload_len = 0;
 			skb->h.th->check =
@@ -2908,7 +2908,7 @@
 		}
 		ipcss = skb_network_offset(skb);
 		ipcso = (void *)&(ip_hdr(skb)->check) - (void *)skb->data;
-		tucss = skb->h.raw - skb->data;
+		tucss = skb_transport_offset(skb);
 		tucso = (void *)&(skb->h.th->check) - (void *)skb->data;
 		tucse = 0;
 
@@ -2950,7 +2950,7 @@
 	uint8_t css;
 
 	if (likely(skb->ip_summed == CHECKSUM_PARTIAL)) {
-		css = skb->h.raw - skb->data;
+		css = skb_transport_offset(skb);
 
 		i = tx_ring->next_to_use;
 		buffer_info = &tx_ring->buffer_info[i];
@@ -3292,7 +3292,7 @@
 		/* TSO Workaround for 82571/2/3 Controllers -- if skb->data
 		* points to just header, pull a few bytes of payload from
 		* frags into skb->data */
-		hdr_len = ((skb->h.raw - skb->data) + (skb->h.th->doff << 2));
+		hdr_len = (skb_transport_offset(skb) + (skb->h.th->doff << 2));
 		if (skb->data_len && (hdr_len == (skb->len - skb->data_len))) {
 			switch (adapter->hw.mac_type) {
 				unsigned int pull_size;