net/vlan: introduce __vlan_hwaccel_copy_tag() helper

Signed-off-by: Michał Mirosław <mirq-linux@rere.qmqm.pl>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/if_vlan.h

@@ -472,6 +472,19 @@ static inline void __vlan_hwaccel_clear_tag(struct sk_buff *skb)
 	skb->vlan_tci = 0;
 }
 
+/**
+ * __vlan_hwaccel_copy_tag - copy hardware accelerated VLAN info from another skb
+ * @dst: skbuff to copy to
+ * @src: skbuff to copy from
+ *
+ * Copies VLAN information from @src to @dst (for branchless code)
+ */
+static inline void __vlan_hwaccel_copy_tag(struct sk_buff *dst, const struct sk_buff *src)
+{
+	dst->vlan_proto = src->vlan_proto;
+	dst->vlan_tci = src->vlan_tci;
+}
+
 /*
  * __vlan_hwaccel_push_inside - pushes vlan tag to the payload
  * @skb: skbuff to tag