Reset MAC on unbinding direct-physical port

direct-physical ports inherit MAC address of physical device
when binding happens (VM created). When VM is deleted this
MAC has to be cleared so other ports may be bound to same device
without conflicts.

Change-Id: I9dc8562546e9a7365d18492678f7fc1cb3553622
Closes-Bug: #1830383

neutron/plugins/ml2/plugin.py

@@ -367,6 +367,18 @@ def _check_mac_update_allowed(self, orig_port, port, binding):
                                 new_mac=port['mac_address'])
         return mac_change
 
+    def _reset_mac_for_direct_physical(self, orig_port, port, binding):
+        # when unbinding direct-physical port we need to free
+        # physical device MAC address so that other ports may reuse it
+        if (binding.vnic_type == portbindings.VNIC_DIRECT_PHYSICAL and
+                port.get('device_id') == '' and
+                port.get('device_owner') == '' and
+                orig_port['device_id'] != ''):
+            port['mac_address'] = self._generate_macs()[0]
+            return True
+        else:
+            return False
+
     @registry.receives(resources.AGENT, [events.AFTER_UPDATE])
     def _retry_binding_revived_agents(self, resource, event, trigger,
                                       payload=None):
@@ -1629,6 +1641,8 @@ def update_port(self, context, id, port):
                 raise exc.PortNotFound(port_id=id)
             mac_address_updated = self._check_mac_update_allowed(
                 port_db, attrs, binding)
+            mac_address_updated |= self._reset_mac_for_direct_physical(
+                port_db, attrs, binding)
             need_port_update_notify |= mac_address_updated
             original_port = self._make_port_dict(port_db)
             updated_port = super(Ml2Plugin, self).update_port(context, id,

neutron/tests/unit/plugins/ml2/test_plugin.py

@@ -1790,6 +1790,37 @@ def test_check_mac_update_allowed_unless_bound(self):
         with testtools.ExpectedException(exc.PortBound):
             self._test_check_mac_update_allowed(portbindings.VIF_TYPE_OVS)
 
+    def _test_reset_mac_for_direct_physical(self, direct_physical=True,
+                                            unbinding=True):
+        plugin = directory.get_plugin()
+        port = {'device_id': '123', 'device_owner': 'compute:nova'}
+        new_attrs = ({'device_id': '', 'device_owner': ''} if unbinding else
+            {'name': 'new'})
+        binding = mock.Mock()
+        binding.vnic_type = (
+            portbindings.VNIC_DIRECT_PHYSICAL if direct_physical else
+            portbindings.VNIC_NORMAL)
+        new_mac = plugin._reset_mac_for_direct_physical(
+            port, new_attrs, binding)
+        if direct_physical and unbinding:
+            self.assertTrue(new_mac)
+            self.assertIsNotNone(new_attrs.get('mac_address'))
+        else:
+            self.assertFalse(new_mac)
+            self.assertIsNone(new_attrs.get('mac_address'))
+
+    def test_reset_mac_for_direct_physical(self):
+        self._test_reset_mac_for_direct_physical()
+
+    def test_reset_mac_for_direct_physical_not_physycal(self):
+        self._test_reset_mac_for_direct_physical(False, True)
+
+    def test_reset_mac_for_direct_physical_no_unbinding(self):
+        self._test_reset_mac_for_direct_physical(True, False)
+
+    def test_reset_mac_for_direct_physical_no_unbinding_not_physical(self):
+        self._test_reset_mac_for_direct_physical(False, False)
+
     def test__device_to_port_id_prefix_names(self):
         input_output = [('sg-abcdefg', 'abcdefg'),
                         ('tap123456', '123456'),