+	vlan_priority = (skb->vlan_tci & VLAN_PRIO_MASK) >> VLAN_PRIO_SHIFT;
+	if (vlan_priority > 0)
+		return vlan_priority;

Is this really correct? For once, checking vlan_priority for non-zero
seems weird since that ought to be a valid value -- is there no other
way to determine that the value is valid?

Also, this gives you a 2-bit value, while the return value should be a
3-bit value, maybe you need to shift this up by one to spread into the
correct buckets?

johannes