-For a non-VLAN PIF, the datapath name is the bridge name.
-For a VLAN PIF, the datapath name is the bridge name for the PIF's VLAN slave.
+A non-VLAN PIF is its own datapath PIF, except that a bridgeless PIF has
+no datapath PIF at all.
+A VLAN PIF's datapath PIF is its VLAN slave's datapath PIF.