net: Add ndo_gso_check

Add ndo_gso_check which a device can define to indicate whether is
is capable of doing GSO on a packet. This funciton would be called from
the stack to determine whether software GSO is needed to be done. A
driver should populate this function if it advertises GSO types for
which there are combinations that it wouldn't be able to handle. For
instance a device that performs UDP tunneling might only implement
support for transparent Ethernet bridging type of inner packets
or might have limitations on lengths of inner headers.

Signed-off-by: Tom Herbert <therbert@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/xen-netfront.c b/drivers/net/xen-netfront.c
index ca82f54..3c0b375 100644
--- a/drivers/net/xen-netfront.c
+++ b/drivers/net/xen-netfront.c
@@ -638,7 +638,7 @@
 
 	if (unlikely(!netif_carrier_ok(dev) ||
 		     (slots > 1 && !xennet_can_sg(dev)) ||
-		     netif_needs_gso(skb, netif_skb_features(skb)))) {
+		     netif_needs_gso(dev, skb, netif_skb_features(skb)))) {
 		spin_unlock_irqrestore(&queue->tx_lock, flags);
 		goto drop;
 	}