def _vm_port_updated(self, ovs_port):
        lport_id = ovs_port.get_iface_id()
        lport = self._get_lport(lport_id)
        if lport is None:
            LOG.warning(_LW("No logical port found for ovs port: %s")
                        % str(ovs_port))
            return
        topic = lport.get_topic()
        self._add_to_topic_subscribed(topic, lport_id)

        # update lport, notify apps
        ovs_port_id = ovs_port.get_id()
        self.ovs_to_lport_mapping[ovs_port_id] = {'lport_id': lport_id,
                                                  'topic': topic}
        LOG.info(str(lport) % _LI("A local logical port(%s) is online"))

        try:
            self.controller.logical_port_updated(lport)
        except Exception:
            LOG.exception(_LE('Failed to process logical port online '
                              'event: %s') % str(lport))
dataset/ETHPy150Open openstack/dragonflow/dragonflow/controller/topology.py/Topology._vm_port_updated/swapped operands of `%`