- /* Adds 'netdev' as a new port in 'dpif'. If successful, sets '*port_no'
- * to the new port's port number. */
+ /* Adds 'netdev' as a new port in 'dpif'. If '*port_no' is not
+ * UINT16_MAX, attempts to use that as the port's port number.
+ *
+ * If port is successfully added, sets '*port_no' to the new port's
+ * port number. Returns EBUSY if caller attempted to choose a port
+ * number, and it was in use. */