fou: Add GRO support

Implement fou_gro_receive and fou_gro_complete, and populate these
in the correponsing udp_offloads for the socket. Added ipproto to
udp_offloads and pass this from UDP to the fou GRO routine in proto
field of napi_gro_cb structure.

Signed-off-by: Tom Herbert <therbert@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv4/udp_offload.c

@@ -276,6 +276,7 @@ unflush:
 
 	skb_gro_pull(skb, sizeof(struct udphdr)); /* pull encapsulating udp header */
 	skb_gro_postpull_rcsum(skb, uh, sizeof(struct udphdr));
+	NAPI_GRO_CB(skb)->proto = uo_priv->offload->ipproto;
 	pp = uo_priv->offload->callbacks.gro_receive(head, skb);
 
 out_unlock:
@@ -329,8 +330,10 @@ int udp_gro_complete(struct sk_buff *skb, int nhoff)
 			break;
 	}
 
-	if (uo_priv != NULL)
+	if (uo_priv != NULL) {
+		NAPI_GRO_CB(skb)->proto = uo_priv->offload->ipproto;
 		err = uo_priv->offload->callbacks.gro_complete(skb, nhoff + sizeof(struct udphdr));
+	}
 
 	rcu_read_unlock();
 	return err;