gre: Set inner mac header in gro complete

Set the inner mac header to point to the GRE payload when doing GRO. This is needed if we proceed to send the packet through GRE GSO which now uses the inner mac header instead of inner network header to determine the length of encapsulation headers.

---
 net/ipv4/gre_offload.c | 3 +++
 1 file changed, 3 insertions(+)

index bb5947b..51973dd 100644
@@ -247,6 +247,9 @@ static int gre_gro_complete(struct sk_buff *skb, int nhoff)
 		err = ptype->callbacks.gro_complete(skb, nhoff + grehlen);
 
 	rcu_read_unlock();
+
+	skb_set_inner_mac_header(skb, nhoff + grehlen);
+
 	return err;
 }
 

2.2.0.rc0.207.ga3a616c