net: allow multiple dev per napi with GRO

GRO assumes that there is a one-to-one relationship between NAPI
structure and network device. Some devices like sky2 share multiple
devices on a single interrupt so only have one NAPI handler. Rather than
split GRO from NAPI, just have GRO assume if device changes that
it is a different flow.
Signed-off-by: NStephen Hemminger <shemminger@vyatta.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/core/dev.c

@@ -2472,8 +2472,9 @@ static int __napi_gro_receive(struct napi_struct *napi, struct sk_buff *skb)
 		return GRO_NORMAL;
 
 	for (p = napi->gro_list; p; p = p->next) {
-		NAPI_GRO_CB(p)->same_flow = !compare_ether_header(
-			skb_mac_header(p), skb_gro_mac_header(skb));
+		NAPI_GRO_CB(p)->same_flow = (p->dev == skb->dev)
+			&& !compare_ether_header(skb_mac_header(p),
+						 skb_gro_mac_header(skb));
 		NAPI_GRO_CB(p)->flush = 0;
 	}