i40e: Add support for ATR w/ IPv6 extension headers

BugLink: http://bugs.launchpad.net/bugs/1547674

This patch updates the code for determining the L4 protocol and L3 header
length so that when IPv6 extension headers are being used we can determine
the offset and type of the L4 protocol.
Signed-off-by: Alexander Duyck <aduyck@mirantis.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
(cherry picked from net-next commit ffcc55c0)
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>

drivers/net/ethernet/intel/i40e/i40e_txrx.c

@@ -2045,7 +2045,7 @@ static void i40e_atr(struct i40e_ring *tx_ring, struct sk_buff *skb,
 	struct tcphdr *th;
 	unsigned int hlen;
 	u32 flex_ptype, dtype_cmd;
-	u8 l4_proto;
+	int l4_proto;
 	u16 i;
 
 	/* make sure ATR is enabled */
@@ -2063,25 +2063,23 @@ static void i40e_atr(struct i40e_ring *tx_ring, struct sk_buff *skb,
 	if (!(tx_flags & (I40E_TX_FLAGS_IPV4 | I40E_TX_FLAGS_IPV6)))
 		return;
 
-	if (!(tx_flags & I40E_TX_FLAGS_UDP_TUNNEL)) {
 	/* snag network header to get L4 type and address */
-		hdr.network = skb_network_header(skb);
+	hdr.network = (tx_flags & I40E_TX_FLAGS_UDP_TUNNEL) ?
+		      skb_inner_network_header(skb) : skb_network_header(skb);
 
+	/* Note: tx_flags gets modified to reflect inner protocols in
+	 * tx_enable_csum function if encap is enabled.
+	 */
+	if (tx_flags & I40E_TX_FLAGS_IPV4) {
 		/* access ihl as u8 to avoid unaligned access on ia64 */
-		if (tx_flags & I40E_TX_FLAGS_IPV4)
 		hlen = (hdr.network[0] & 0x0F) << 2;
-		else
-			hlen = sizeof(struct ipv6hdr);
+		l4_proto = hdr.ipv4->protocol;
 	} else {
-		hdr.network = skb_inner_network_header(skb);
-		hlen = skb_inner_network_header_len(skb);
+		hlen = hdr.network - skb->data;
+		l4_proto = ipv6_find_hdr(skb, &hlen, IPPROTO_TCP, NULL, NULL);
+		hlen -= hdr.network - skb->data;
 	}
 
-	/* Note: tx_flags gets modified to reflect inner protocols in
-	 * tx_enable_csum function if encap is enabled.
-	 */
-	l4_proto = (tx_flags & I40E_TX_FLAGS_IPV4) ? hdr.ipv4->protocol :
-						     hdr.ipv6->nexthdr;
 	if (l4_proto != IPPROTO_TCP)
 		return;