Fix update of network's segmentation id

In patch [1] there was added usage of context parameter in method
get_vif_type in openvswitch mech_driver.
This exposed that previously "wrong" context was passed to this method
in _update_segmentation_id() method in ml2 plugin and that caused
raising AttributeError as "Context" object didn't have attribute
'current'.

This patch adds new method "get_supported_vif_type" to mechanism
drivers and this method don't need context to return what vif_types
are supported regarding agent type.

[1] https://review.opendev.org/#/c/658784/

Change-Id: Ic6c738db28208e5009f78bb52598eb3c141f639f
Related-Bug: #1832985

neutron/plugins/ml2/drivers/mech_agent.py

@@ -279,6 +279,10 @@ class SimpleAgentMechanismDriverBase(AgentMechanismDriverBase):
     def get_vif_details(self, context, agent, segment):
         return self.vif_details
 
+    def get_supported_vif_type(self, agent):
+        """Return supported vif type appropriate for the agent."""
+        return self.vif_type
+
     def get_vif_type(self, context, agent, segment):
         """Return the vif type appropriate for the agent and segment."""
         return self.vif_type

neutron/plugins/ml2/drivers/openvswitch/mech_driver/mech_openvswitch.py

@@ -132,11 +132,7 @@ class OpenvswitchMechanismDriver(mech_agent.SimpleAgentMechanismDriverBase):
             return
         super(OpenvswitchMechanismDriver, self).bind_port(context)
 
-    def get_vif_type(self, context, agent, segment):
-        if (context.current.get(portbindings.VNIC_TYPE) ==
-                portbindings.VNIC_DIRECT):
-            return portbindings.VIF_TYPE_OVS
-
+    def get_supported_vif_type(self, agent):
         caps = agent['configurations'].get('ovs_capabilities', {})
         if (any(x in caps.get('iface_types', []) for x
                 in [a_const.OVS_DPDK_VHOST_USER,
@@ -146,6 +142,12 @@ class OpenvswitchMechanismDriver(mech_agent.SimpleAgentMechanismDriverBase):
             return portbindings.VIF_TYPE_VHOST_USER
         return self.vif_type
 
+    def get_vif_type(self, context, agent, segment):
+        if (context.current.get(portbindings.VNIC_TYPE) ==
+                portbindings.VNIC_DIRECT):
+            return portbindings.VIF_TYPE_OVS
+        return self.get_supported_vif_type(agent)
+
     def get_vhost_mode(self, iface_types):
         # NOTE(sean-k-mooney): this function converts the ovs vhost user
         # driver mode into the qemu vhost user mode. If OVS is the server,

neutron/plugins/ml2/plugin.py

@@ -846,8 +846,8 @@ class Ml2Plugin(db_base_plugin_v2.NeutronDbPluginV2,
                 agents = self.get_agents(
                     context, filters={'agent_type': [agent_type]})
                 for agent in agents:
-                    vif_types.append(mech_driver.obj.get_vif_type(
-                        context, agent, segments[0]))
+                    vif_types.append(
+                        mech_driver.obj.get_supported_vif_type(agent))
 
         filter_obj = obj_utils.NotIn(vif_types)
         filters = {portbindings.VIF_TYPE:

neutron/tests/unit/plugins/ml2/drivers/mechanism_test.py

@@ -277,6 +277,9 @@ class TestMechanismDriverWithAgent(mech_agent.AgentMechanismDriverBase,
         self.bound_ports = set()
         self._agent_type = 'test_mechanism_driver_agent'
 
+    def get_supported_vif_type(self, agent):
+        return VIF_TYPE_TEST
+
     def get_vif_type(self, context, agent, segment):
         return VIF_TYPE_TEST