-static void gre_build_header(struct sk_buff *skb,
- const struct vport *vport,
- const struct tnl_mutable_config *mutable)
+static struct sk_buff *gre_build_header(struct sk_buff *skb,
+ const struct vport *vport,
+ const struct tnl_mutable_config *mutable,
+ struct dst_entry *dst)