commit 7e31f2ae41b4512afd2b3dd4fb72fcd16ef0a373
Author: Rodolfo Alonso Hernandez <ralonsoh@redhat.com>
Date:   Wed Oct 7 10:20:20 2020 +0000

    Do not load "qos-fip" if "qos" plugin is not loaded
    
    If QoS service plugin is not loaded, the L3 QoS extension in the OVN
    L3 plugin should not be loaded neither.
    
    Prior to this patch, the extension drivers were checked to find the
    QoS extension. Although it is a misconfiguration to have the QoS
    extension without loading the QoS driver, that is handled correctly
    by the Neutron server, disabling the extension silently.
    
    Closes-Bug: #1898842
    Related-Bug: #1877408
    
    Change-Id: Iea5ff76fe652ab1c04e23850b9259547c1d54365

diff --git a/neutron/services/ovn_l3/plugin.py b/neutron/services/ovn_l3/plugin.py
index cc38f1d..942b0e6 100644
--- a/neutron/services/ovn_l3/plugin.py
+++ b/neutron/services/ovn_l3/plugin.py
@@ -20,7 +20,6 @@ from neutron.quota import resource_registry
 from neutron_lib.api.definitions import external_net
 from neutron_lib.api.definitions import portbindings
 from neutron_lib.api.definitions import provider_net as pnet
-from neutron_lib.api.definitions import qos as qos_api
 from neutron_lib.callbacks import events
 from neutron_lib.callbacks import registry
 from neutron_lib.callbacks import resources
@@ -31,7 +30,6 @@ from neutron_lib.exceptions import availability_zone as az_exc
 from neutron_lib.plugins import constants as plugin_constants
 from neutron_lib.plugins import directory
 from neutron_lib.services import base as service_base
-from oslo_config import cfg
 from oslo_log import log
 from oslo_utils import excutils
 
@@ -96,8 +94,9 @@ class OVNL3RouterPlugin(service_base.ServicePluginBase,
 
     @staticmethod
     def disable_qos_fip_extension_by_extension_drivers(aliases):
-        if (qos_api.ALIAS not in cfg.CONF.ml2.extension_drivers and
-                qos_fip_api.FIP_QOS_ALIAS in aliases):
+        qos_service_plugin = directory.get_plugin(plugin_constants.QOS)
+        qos_aliases = qos_fip_api.FIP_QOS_ALIAS in aliases
+        if not qos_service_plugin and qos_aliases:
             aliases.remove(qos_fip_api.FIP_QOS_ALIAS)
 
     @property