diff --git a/neutron/db/_resource_extend.py b/neutron/db/_resource_extend.py
index a5456d19129..0f04acbd7b3 100644
--- a/neutron/db/_resource_extend.py
+++ b/neutron/db/_resource_extend.py
@@ -15,6 +15,9 @@ NOTE: This module shall not be used by external projects. It will be moved
       to neutron-lib in due course, and then it can be used from there.
 """
 
+import collections
+import inspect
+
 from neutron.common import utils
 
 # This dictionary will store methods for extending API resources.
@@ -25,6 +28,10 @@ _resource_extend_functions = {
     # ...
 }
 
+# This dictionary will store @extends decorated methods with a list of
+# resources that each method will extend on class initialization.
+_DECORATED_EXTEND_METHODS = collections.defaultdict(list)
+
 
 def register_funcs(resource, funcs):
     """Add functions to extend a resource.
@@ -59,3 +66,65 @@ def get_funcs(resource):
 
     """
     return _resource_extend_functions.get(resource, [])
+
+
+def extends(resources):
+    """Use to decorate methods on classes before initialization.
+
+    Any classes that use this must themselves be decorated with the
+    @has_resource_extenders decorator to setup the __new__ method to
+    actually register the instance methods after initialization.
+
+    :param resources: Resource collection names. The decorated method will
+                      be registered with each resource as an extend function.
+    :type resources: list of str
+
+    """
+    def decorator(method):
+        _DECORATED_EXTEND_METHODS[method].extend(resources)
+        return method
+    return decorator
+
+
+def has_resource_extenders(klass):
+    """Decorator to setup __new__ method in classes to extend resources.
+
+    Any method decorated with @extends above is an unbound method on a class.
+    This decorator sets up the class __new__ method to add the bound
+    method to _resource_extend_functions after object instantiation.
+    """
+    orig_new = klass.__new__
+    new_inherited = '__new__' not in klass.__dict__
+
+    @staticmethod
+    def replacement_new(cls, *args, **kwargs):
+        if new_inherited:
+            # class didn't define __new__ so we need to call inherited __new__
+            super_new = super(klass, cls).__new__
+            if super_new is object.__new__:
+                # object.__new__ doesn't accept args nor kwargs
+                instance = super_new(cls)
+            else:
+                instance = super_new(cls, *args, **kwargs)
+        else:
+            instance = orig_new(cls, *args, **kwargs)
+        if getattr(instance, '_DECORATED_METHODS_REGISTERED', False):
+            # Avoid running this logic twice for classes inheriting other
+            # classes with this same decorator. Only one needs to execute
+            # to subscribe all decorated methods.
+            return instance
+        for name, unbound_method in inspect.getmembers(cls):
+            if (not inspect.ismethod(unbound_method) and
+                    not inspect.isfunction(unbound_method)):
+                continue
+            # Handle py27/py34 difference
+            method = getattr(unbound_method, 'im_func', unbound_method)
+            if method not in _DECORATED_EXTEND_METHODS:
+                continue
+            for resource in _DECORATED_EXTEND_METHODS[method]:
+                # Register the bound method for the resourse
+                register_funcs(resource, [method])
+        setattr(instance, '_DECORATED_METHODS_REGISTERED', True)
+        return instance
+    klass.__new__ = replacement_new
+    return klass
diff --git a/neutron/db/address_scope_db.py b/neutron/db/address_scope_db.py
index 3ff6461a21e..5becc826595 100644
--- a/neutron/db/address_scope_db.py
+++ b/neutron/db/address_scope_db.py
@@ -26,6 +26,7 @@ from neutron.objects import base as base_obj
 from neutron.objects import subnetpool as subnetpool_obj
 
 
+@resource_extend.has_resource_extenders
 class AddressScopeDbMixin(ext_address_scope.AddressScopePluginBase):
     """Mixin class to add address scope to db_base_plugin_v2."""
 
@@ -117,7 +118,9 @@ class AddressScopeDbMixin(ext_address_scope.AddressScopePluginBase):
             address_scope = self._get_address_scope(context, id)
             address_scope.delete()
 
-    def _extend_network_dict_address_scope(self, network_res, network_db):
+    @staticmethod
+    @resource_extend.extends([attr.NETWORKS])
+    def _extend_network_dict_address_scope(network_res, network_db):
         network_res[ext_address_scope.IPV4_ADDRESS_SCOPE] = None
         network_res[ext_address_scope.IPV6_ADDRESS_SCOPE] = None
         subnetpools = {subnet.subnetpool for subnet in network_db.subnets
@@ -132,6 +135,3 @@ class AddressScopeDbMixin(ext_address_scope.AddressScopePluginBase):
             if subnetpool['ip_version'] == constants.IP_VERSION_6:
                 network_res[ext_address_scope.IPV6_ADDRESS_SCOPE] = as_id
         return network_res
-
-    resource_extend.register_funcs(
-        attr.NETWORKS, ['_extend_network_dict_address_scope'])
diff --git a/neutron/db/allowedaddresspairs_db.py b/neutron/db/allowedaddresspairs_db.py
index ac123b88f6b..114b01142dd 100644
--- a/neutron/db/allowedaddresspairs_db.py
+++ b/neutron/db/allowedaddresspairs_db.py
@@ -26,6 +26,7 @@ from neutron.objects.port.extensions import (allowedaddresspairs
     as obj_addr_pair)
 
 
+@resource_extend.has_resource_extenders
 class AllowedAddressPairsMixin(object):
     """Mixin class for allowed address pairs."""
 
@@ -63,19 +64,19 @@ class AllowedAddressPairsMixin(object):
         return [self._make_allowed_address_pairs_dict(pair.db_obj)
                 for pair in pairs]
 
-    def _extend_port_dict_allowed_address_pairs(self, port_res, port_db):
+    @staticmethod
+    @resource_extend.extends([attr.PORTS])
+    def _extend_port_dict_allowed_address_pairs(port_res, port_db):
         # If port_db is provided, allowed address pairs will be accessed via
         # sqlalchemy models. As they're loaded together with ports this
         # will not cause an extra query.
         allowed_address_pairs = [
-            self._make_allowed_address_pairs_dict(address_pair) for
+            AllowedAddressPairsMixin._make_allowed_address_pairs_dict(
+                address_pair) for
             address_pair in port_db.allowed_address_pairs]
         port_res[addr_pair.ADDRESS_PAIRS] = allowed_address_pairs
         return port_res
 
-    resource_extend.register_funcs(
-        attr.PORTS, ['_extend_port_dict_allowed_address_pairs'])
-
     def _delete_allowed_address_pairs(self, context, id):
         obj_addr_pair.AllowedAddressPair.delete_objects(
             context, port_id=id)
diff --git a/neutron/db/availability_zone/network.py b/neutron/db/availability_zone/network.py
index 422ed2ca7b3..6e9fccf0dcd 100644
--- a/neutron/db/availability_zone/network.py
+++ b/neutron/db/availability_zone/network.py
@@ -11,20 +11,23 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
+from neutron_lib.plugins import directory
+
 from neutron.api.v2 import attributes
 from neutron.db import _resource_extend as resource_extend
 from neutron.extensions import availability_zone as az_ext
 from neutron.extensions import network_availability_zone as net_az
 
 
+@resource_extend.has_resource_extenders
 class NetworkAvailabilityZoneMixin(net_az.NetworkAvailabilityZonePluginBase):
     """Mixin class to enable network's availability zone attributes."""
 
-    def _extend_availability_zone(self, net_res, net_db):
+    @staticmethod
+    @resource_extend.extends([attributes.NETWORKS])
+    def _extend_availability_zone(net_res, net_db):
         net_res[az_ext.AZ_HINTS] = az_ext.convert_az_string_to_list(
             net_db[az_ext.AZ_HINTS])
+        plugin = directory.get_plugin()
         net_res[az_ext.AVAILABILITY_ZONES] = (
-            self.get_network_availability_zones(net_db))
-
-    resource_extend.register_funcs(
-        attributes.NETWORKS, ['_extend_availability_zone'])
+            plugin.get_network_availability_zones(net_db))
diff --git a/neutron/db/availability_zone/router.py b/neutron/db/availability_zone/router.py
index 681ef699da0..6a5d0966f0c 100644
--- a/neutron/db/availability_zone/router.py
+++ b/neutron/db/availability_zone/router.py
@@ -11,32 +11,33 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
+from neutron_lib import constants
+from neutron_lib.plugins import directory
+
 from neutron.callbacks import events
 from neutron.callbacks import registry
 from neutron.callbacks import resources
 from neutron.common import utils
-from neutron.db import db_base_plugin_v2
+from neutron.db import _resource_extend as resource_extend
 from neutron.db import l3_attrs_db
 from neutron.extensions import availability_zone as az_ext
 from neutron.extensions import l3
 
 
+@resource_extend.has_resource_extenders
 @registry.has_registry_receivers
 class RouterAvailabilityZoneMixin(l3_attrs_db.ExtraAttributesMixin):
     """Mixin class to enable router's availability zone attributes."""
 
-    def __new__(cls, *args, **kwargs):
-        inst = super(RouterAvailabilityZoneMixin, cls).__new__(
-            cls, *args, **kwargs)
-        db_base_plugin_v2.NeutronDbPluginV2.register_dict_extend_funcs(
-            l3.ROUTERS, [inst._add_az_to_response])
-        return inst
-
-    def _add_az_to_response(self, plugin, router_res, router_db):
-        if not utils.is_extension_supported(self, 'router_availability_zone'):
+    @staticmethod
+    @resource_extend.extends([l3.ROUTERS])
+    def _add_az_to_response(router_res, router_db):
+        l3_plugin = directory.get_plugin(constants.L3)
+        if not utils.is_extension_supported(l3_plugin,
+                                            'router_availability_zone'):
             return
         router_res['availability_zones'] = (
-            self.get_router_availability_zones(router_db))
+            l3_plugin.get_router_availability_zones(router_db))
 
     @registry.receives(resources.ROUTER, [events.PRECOMMIT_CREATE])
     def _process_az_request(self, resource, event, trigger, context,
diff --git a/neutron/db/common_db_mixin.py b/neutron/db/common_db_mixin.py
index c52427a8c53..bc20d05657c 100644
--- a/neutron/db/common_db_mixin.py
+++ b/neutron/db/common_db_mixin.py
@@ -17,7 +17,6 @@ import weakref
 
 from neutron_lib.db import utils as db_utils
 from oslo_db.sqlalchemy import utils as sa_utils
-import six
 from sqlalchemy import and_
 from sqlalchemy.ext import associationproxy
 from sqlalchemy import or_
@@ -36,6 +35,13 @@ model_query = ndb_utils.model_query
 resource_fields = ndb_utils.resource_fields
 
 
+def _resolve_ref(ref):
+    """Handles dereference of weakref."""
+    if isinstance(ref, weakref.ref):
+        ref = ref()
+    return ref
+
+
 class CommonDbMixin(object):
     """Common methods used in core and service plugins."""
 
@@ -85,11 +91,11 @@ class CommonDbMixin(object):
                 query_filter = (model.tenant_id == context.tenant_id)
         # Execute query hooks registered from mixins and plugins
         for hook in _model_query.get_hooks(model):
-            query_hook = self._resolve_ref(hook.get('query'))
+            query_hook = _resolve_ref(hook.get('query'))
             if query_hook:
                 query = query_hook(context, model, query)
 
-            filter_hook = self._resolve_ref(hook.get('filter'))
+            filter_hook = _resolve_ref(hook.get('filter'))
             if filter_hook:
                 query_filter = filter_hook(context, model, query_filter)
 
@@ -164,31 +170,19 @@ class CommonDbMixin(object):
                         query = query.outerjoin(model.rbac_entries)
                     query = query.filter(is_shared)
             for hook in _model_query.get_hooks(model):
-                result_filter = self._resolve_ref(
-                    hook.get('result_filters', None))
+                result_filter = _resolve_ref(hook.get('result_filters', None))
 
                 if result_filter:
                     query = result_filter(query, filters)
         return query
 
-    def _resolve_ref(self, ref):
-        """Finds string ref functions, handles dereference of weakref."""
-        if isinstance(ref, six.string_types):
-            ref = getattr(self, ref, None)
-        if isinstance(ref, weakref.ref):
-            ref = ref()
-        return ref
-
-    def _apply_dict_extend_functions(self, resource_type,
+    @staticmethod
+    def _apply_dict_extend_functions(resource_type,
                                      response, db_object):
         for func in _resource_extend.get_funcs(resource_type):
-            args = (response, db_object)
-            if not isinstance(func, six.string_types):
-                # must call unbound method - use self as 1st argument
-                args = (self,) + args
-            func = self._resolve_ref(func)
-            if func:
-                func(*args)
+            resolved_func = _resolve_ref(func)
+            if resolved_func:
+                resolved_func(response, db_object)
 
     def _get_collection_query(self, context, model, filters=None,
                               sorts=None, limit=None, marker_obj=None,
diff --git a/neutron/db/data_plane_status_db.py b/neutron/db/data_plane_status_db.py
index 4e5c23aefc2..92a87aa9b58 100644
--- a/neutron/db/data_plane_status_db.py
+++ b/neutron/db/data_plane_status_db.py
@@ -40,7 +40,8 @@ class DataPlaneStatusMixin(object):
         else:
             self._process_create_port_data_plane_status(context, data, res)
 
-    def _extend_port_data_plane_status(self, port_res, port_db):
+    @staticmethod
+    def _extend_port_data_plane_status(port_res, port_db):
         port_res[dps_lib.DATA_PLANE_STATUS] = None
 
         if port_db.get(dps_lib.DATA_PLANE_STATUS):
diff --git a/neutron/db/dns_db.py b/neutron/db/dns_db.py
index f71d2a4a74c..652284500ff 100644
--- a/neutron/db/dns_db.py
+++ b/neutron/db/dns_db.py
@@ -41,6 +41,7 @@ class DNSActionsData(object):
         self.previous_dns_domain = previous_dns_domain
 
 
+@resource_extend.has_resource_extenders
 class DNSDbMixin(object):
     """Mixin class to add DNS methods to db_base_plugin_v2."""
 
@@ -63,7 +64,9 @@ class DNSDbMixin(object):
             raise dns.ExternalDNSDriverNotFound(
                 driver=cfg.CONF.external_dns_driver)
 
-    def _extend_floatingip_dict_dns(self, floatingip_res, floatingip_db):
+    @staticmethod
+    @resource_extend.extends([l3.FLOATINGIPS])
+    def _extend_floatingip_dict_dns(floatingip_res, floatingip_db):
         floatingip_res['dns_domain'] = ''
         floatingip_res['dns_name'] = ''
         if floatingip_db.dns:
@@ -71,9 +74,6 @@ class DNSDbMixin(object):
             floatingip_res['dns_name'] = floatingip_db.dns['dns_name']
         return floatingip_res
 
-    resource_extend.register_funcs(
-        l3.FLOATINGIPS, ['_extend_floatingip_dict_dns'])
-
     def _process_dns_floatingip_create_precommit(self, context,
                                                  floatingip_data, req_data):
         # expects to be called within a plugin's session
diff --git a/neutron/db/external_net_db.py b/neutron/db/external_net_db.py
index bed831228b6..d399821d8af 100644
--- a/neutron/db/external_net_db.py
+++ b/neutron/db/external_net_db.py
@@ -64,6 +64,7 @@ def _network_result_filter_hook(query, filters):
     return query.filter(~models_v2.Network.external.has())
 
 
+@resource_extend.has_resource_extenders
 @registry.has_registry_receivers
 class External_net_db_mixin(object):
     """Mixin class to add external network methods to db_base_plugin_v2."""
@@ -81,14 +82,13 @@ class External_net_db_mixin(object):
         return net_obj.ExternalNetwork.objects_exist(
             context, network_id=net_id)
 
-    def _extend_network_dict_l3(self, network_res, network_db):
+    @staticmethod
+    @resource_extend.extends([attributes.NETWORKS])
+    def _extend_network_dict_l3(network_res, network_db):
         # Comparing with None for converting uuid into bool
         network_res[external_net.EXTERNAL] = network_db.external is not None
         return network_res
 
-    resource_extend.register_funcs(
-        attributes.NETWORKS, ['_extend_network_dict_l3'])
-
     def _process_l3_create(self, context, net_data, req_data):
         external = req_data.get(external_net.EXTERNAL)
         external_set = validators.is_attr_set(external)
diff --git a/neutron/db/extradhcpopt_db.py b/neutron/db/extradhcpopt_db.py
index 409fed60ef8..beceb54d793 100644
--- a/neutron/db/extradhcpopt_db.py
+++ b/neutron/db/extradhcpopt_db.py
@@ -20,6 +20,7 @@ from neutron.extensions import extra_dhcp_opt as edo_ext
 from neutron.objects.port.extensions import extra_dhcp_opt as obj_extra_dhcp
 
 
+@resource_extend.has_resource_extenders
 class ExtraDhcpOptMixin(object):
     """Mixin class to add extra options to the DHCP opts file
     and associate them to a port.
@@ -114,12 +115,11 @@ class ExtraDhcpOptMixin(object):
 
         return bool(dopts)
 
-    def _extend_port_dict_extra_dhcp_opt(self, res, port):
+    @staticmethod
+    @resource_extend.extends([attributes.PORTS])
+    def _extend_port_dict_extra_dhcp_opt(res, port):
         res[edo_ext.EXTRADHCPOPTS] = [{'opt_name': dho.opt_name,
                                        'opt_value': dho.opt_value,
                                        'ip_version': dho.ip_version}
                                       for dho in port.dhcp_opts]
         return res
-
-    resource_extend.register_funcs(
-        attributes.PORTS, ['_extend_port_dict_extra_dhcp_opt'])
diff --git a/neutron/db/extraroute_db.py b/neutron/db/extraroute_db.py
index 4a781e2cea8..d18597a79d5 100644
--- a/neutron/db/extraroute_db.py
+++ b/neutron/db/extraroute_db.py
@@ -39,18 +39,18 @@ extra_route_opts = [
 cfg.CONF.register_opts(extra_route_opts)
 
 
+@resource_extend.has_resource_extenders
 class ExtraRoute_dbonly_mixin(l3_db.L3_NAT_dbonly_mixin):
     """Mixin class to support extra route configuration on router."""
 
-    def _extend_router_dict_extraroute(self, router_res, router_db):
+    @staticmethod
+    @resource_extend.extends([l3.ROUTERS])
+    def _extend_router_dict_extraroute(router_res, router_db):
         router_res['routes'] = (ExtraRoute_dbonly_mixin.
                                 _make_extra_route_list(
                                     router_db['route_list']
                                 ))
 
-    resource_extend.register_funcs(
-        l3.ROUTERS, ['_extend_router_dict_extraroute'])
-
     def update_router(self, context, id, router):
         r = router['router']
         if 'routes' in r:
diff --git a/neutron/db/l3_attrs_db.py b/neutron/db/l3_attrs_db.py
index 5d8b0efa92a..ec3bae78eef 100644
--- a/neutron/db/l3_attrs_db.py
+++ b/neutron/db/l3_attrs_db.py
@@ -33,10 +33,13 @@ def get_attr_info():
             }
 
 
+@resource_extend.has_resource_extenders
 class ExtraAttributesMixin(object):
     """Mixin class to enable router's extra attributes."""
 
-    def _extend_extra_router_dict(self, router_res, router_db):
+    @staticmethod
+    @resource_extend.extends([l3.ROUTERS])
+    def _extend_extra_router_dict(router_res, router_db):
         extra_attrs = router_db['extra_attributes'] or {}
         for name, info in get_attr_info().items():
             from_db = info.get('transform_from_db', lambda x: x)
@@ -61,6 +64,3 @@ class ExtraAttributesMixin(object):
                 return
             raise RuntimeError(_("Tried to set a key '%s' that doesn't exist "
                                  "in the extra attributes table.") % key)
-
-    resource_extend.register_funcs(
-        l3.ROUTERS, ['_extend_extra_router_dict'])
diff --git a/neutron/db/l3_gwmode_db.py b/neutron/db/l3_gwmode_db.py
index ff44c29e424..8987dd133ba 100644
--- a/neutron/db/l3_gwmode_db.py
+++ b/neutron/db/l3_gwmode_db.py
@@ -38,13 +38,13 @@ setattr(l3_models.Router, 'enable_snat',
                   nullable=False))
 
 
+@resource_extend.has_resource_extenders
 class L3_NAT_dbonly_mixin(l3_db.L3_NAT_dbonly_mixin):
     """Mixin class to add configurable gateway modes."""
 
-    resource_extend.register_funcs(
-        l3.ROUTERS, ['_extend_router_dict_gw_mode'])
-
-    def _extend_router_dict_gw_mode(self, router_res, router_db):
+    @staticmethod
+    @resource_extend.extends([l3.ROUTERS])
+    def _extend_router_dict_gw_mode(router_res, router_db):
         if router_db.gw_port_id:
             nw_id = router_db.gw_port['network_id']
             router_res[EXTERNAL_GW_INFO] = {
diff --git a/neutron/db/portbindings_base.py b/neutron/db/portbindings_base.py
index c9b51a7fc96..d580029ea04 100644
--- a/neutron/db/portbindings_base.py
+++ b/neutron/db/portbindings_base.py
@@ -13,11 +13,16 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
+from neutron_lib.plugins import directory
+
 from neutron.api.v2 import attributes
 from neutron.db import _resource_extend as resource_extend
 
 
+@resource_extend.has_resource_extenders
 class PortBindingBaseMixin(object):
+
+    # Initialized by core plugin or ml2 mechanism driver(s)
     base_binding_dict = None
 
     def _process_portbindings_create_and_update(self, context, port_data,
@@ -28,13 +33,10 @@ class PortBindingBaseMixin(object):
         if self.base_binding_dict:
             port_res.update(self.base_binding_dict)
 
-
-def _extend_port_dict_binding(plugin, port_res, port_db):
-    if not isinstance(plugin, PortBindingBaseMixin):
-        return
-    plugin.extend_port_dict_binding(port_res, port_db)
-
-
-def register_port_dict_function():
-    resource_extend.register_funcs(
-        attributes.PORTS, [_extend_port_dict_binding])
+    @staticmethod
+    @resource_extend.extends([attributes.PORTS])
+    def _extend_port_dict_binding(port_res, port_db):
+        plugin = directory.get_plugin()
+        if not isinstance(plugin, PortBindingBaseMixin):
+            return
+        plugin.extend_port_dict_binding(port_res, port_db)
diff --git a/neutron/db/portbindings_db.py b/neutron/db/portbindings_db.py
index 65832f633a3..4de5b2ad7ba 100644
--- a/neutron/db/portbindings_db.py
+++ b/neutron/db/portbindings_db.py
@@ -15,6 +15,7 @@
 
 from neutron_lib.api.definitions import portbindings
 from neutron_lib.api import validators
+from neutron_lib.plugins import directory
 
 from neutron.api.v2 import attributes
 from neutron.db import _model_query as model_query
@@ -40,8 +41,8 @@ def _port_result_filter_hook(query, filters):
     return query
 
 
+@resource_extend.has_resource_extenders
 class PortBindingMixin(portbindings_base.PortBindingBaseMixin):
-    extra_binding_dict = None
 
     def __new__(cls, *args, **kwargs):
         model_query.register_hook(
@@ -101,11 +102,10 @@ class PortBindingMixin(portbindings_base.PortBindingBaseMixin):
         host = port_db.portbinding.host if port_db.portbinding else None
         self._extend_port_dict_binding_host(port_res, host)
 
-
-def _extend_port_dict_binding(plugin, port_res, port_db):
-    if not isinstance(plugin, PortBindingMixin):
-        return
-    plugin.extend_port_dict_binding(port_res, port_db)
-
-
-resource_extend.register_funcs(attributes.PORTS, [_extend_port_dict_binding])
+    @staticmethod
+    @resource_extend.extends([attributes.PORTS])
+    def _extend_port_dict_binding(port_res, port_db):
+        plugin = directory.get_plugin()
+        if not isinstance(plugin, PortBindingMixin):
+            return
+        plugin.extend_port_dict_binding(port_res, port_db)
diff --git a/neutron/db/portsecurity_db.py b/neutron/db/portsecurity_db.py
index bd551270bbf..0129b8573e1 100644
--- a/neutron/db/portsecurity_db.py
+++ b/neutron/db/portsecurity_db.py
@@ -13,6 +13,7 @@
 #    under the License.
 
 from neutron_lib.api import validators
+from neutron_lib.plugins import directory
 
 from neutron.api.v2 import attributes as attrs
 from neutron.common import utils
@@ -21,16 +22,16 @@ from neutron.db import portsecurity_db_common
 from neutron.extensions import portsecurity as psec
 
 
+@resource_extend.has_resource_extenders
 class PortSecurityDbMixin(portsecurity_db_common.PortSecurityDbCommon):
-    resource_extend.register_funcs(
-        attrs.NETWORKS, ['_extend_port_security_dict'])
-    resource_extend.register_funcs(
-        attrs.PORTS, ['_extend_port_security_dict'])
 
-    def _extend_port_security_dict(self, response_data, db_data):
+    @staticmethod
+    @resource_extend.extends([attrs.NETWORKS, attrs.PORTS])
+    def _extend_port_security_dict(response_data, db_data):
+        plugin = directory.get_plugin()
         if ('port-security' in
-            getattr(self, 'supported_extension_aliases', [])):
-            super(PortSecurityDbMixin, self)._extend_port_security_dict(
+                getattr(plugin, 'supported_extension_aliases', [])):
+            super(PortSecurityDbMixin, plugin)._extend_port_security_dict(
                 response_data, db_data)
 
     def _determine_port_security_and_has_ip(self, context, port):
diff --git a/neutron/db/portsecurity_db_common.py b/neutron/db/portsecurity_db_common.py
index 9e319f35893..566f254be6c 100644
--- a/neutron/db/portsecurity_db_common.py
+++ b/neutron/db/portsecurity_db_common.py
@@ -21,7 +21,8 @@ from neutron.objects.port.extensions import port_security as p_ps
 class PortSecurityDbCommon(object):
     """Mixin class to add port security."""
 
-    def _extend_port_security_dict(self, response_data, db_data):
+    @staticmethod
+    def _extend_port_security_dict(response_data, db_data):
         if db_data.get('port_security') is None:
             response_data[psec.PORTSECURITY] = psec.DEFAULT_PORT_SECURITY
         else:
diff --git a/neutron/db/securitygroups_db.py b/neutron/db/securitygroups_db.py
index ad89b6cb7c2..95f679f0bcb 100644
--- a/neutron/db/securitygroups_db.py
+++ b/neutron/db/securitygroups_db.py
@@ -35,6 +35,7 @@ from neutron.db.models import securitygroup as sg_models
 from neutron.extensions import securitygroup as ext_sg
 
 
+@resource_extend.has_resource_extenders
 @registry.has_registry_receivers
 class SecurityGroupDbMixin(ext_sg.SecurityGroupPluginBase):
     """Mixin class to add security group to db_base_plugin_v2."""
@@ -662,7 +663,9 @@ class SecurityGroupDbMixin(ext_sg.SecurityGroupPluginBase):
             resources.SECURITY_GROUP_RULE, events.AFTER_DELETE, self,
             **kwargs)
 
-    def _extend_port_dict_security_group(self, port_res, port_db):
+    @staticmethod
+    @resource_extend.extends([attributes.PORTS])
+    def _extend_port_dict_security_group(port_res, port_db):
         # Security group bindings will be retrieved from the SQLAlchemy
         # model. As they're loaded eagerly with ports because of the
         # joined load they will not cause an extra query.
@@ -671,9 +674,6 @@ class SecurityGroupDbMixin(ext_sg.SecurityGroupPluginBase):
         port_res[ext_sg.SECURITYGROUPS] = security_group_ids
         return port_res
 
-    resource_extend.register_funcs(
-        attributes.PORTS, ['_extend_port_dict_security_group'])
-
     def _process_port_create_security_group(self, context, port,
                                             security_group_ids):
         if validators.is_attr_set(security_group_ids):
diff --git a/neutron/db/standardattrdescription_db.py b/neutron/db/standardattrdescription_db.py
index 98548ece5b4..f2294dea933 100644
--- a/neutron/db/standardattrdescription_db.py
+++ b/neutron/db/standardattrdescription_db.py
@@ -16,17 +16,14 @@ from neutron.db import _resource_extend as resource_extend
 from neutron.db import standard_attr
 
 
+@resource_extend.has_resource_extenders
 class StandardAttrDescriptionMixin(object):
     supported_extension_aliases = ['standard-attr-description']
 
-    def _extend_standard_attr_description(self, res, db_object):
+    @staticmethod
+    @resource_extend.extends(
+        list(standard_attr.get_standard_attr_resource_model_map()))
+    def _extend_standard_attr_description(res, db_object):
         if not hasattr(db_object, 'description'):
             return
         res['description'] = db_object.description
-
-    def __new__(cls, *args, **kwargs):
-        for resource in standard_attr.get_standard_attr_resource_model_map():
-            resource_extend.register_funcs(
-                resource, ['_extend_standard_attr_description'])
-        return super(StandardAttrDescriptionMixin, cls).__new__(cls, *args,
-                                                                **kwargs)
diff --git a/neutron/db/subnet_service_type_db_models.py b/neutron/db/subnet_service_type_db_models.py
index 60f2be95a69..22e77d89998 100644
--- a/neutron/db/subnet_service_type_db_models.py
+++ b/neutron/db/subnet_service_type_db_models.py
@@ -20,13 +20,13 @@ from neutron.api.v2 import attributes
 from neutron.db import _resource_extend as resource_extend
 
 
+@resource_extend.has_resource_extenders
 class SubnetServiceTypeMixin(object):
     """Mixin class to extend subnet with service type attribute"""
 
-    def _extend_subnet_service_types(self, subnet_res, subnet_db):
+    @staticmethod
+    @resource_extend.extends([attributes.SUBNETS])
+    def _extend_subnet_service_types(subnet_res, subnet_db):
         subnet_res['service_types'] = [service_type['service_type'] for
                                        service_type in
                                        subnet_db.service_types]
-
-    resource_extend.register_funcs(
-        attributes.SUBNETS, [_extend_subnet_service_types])
diff --git a/neutron/db/vlantransparent_db.py b/neutron/db/vlantransparent_db.py
index 1af6ad4bbf1..33f76748077 100644
--- a/neutron/db/vlantransparent_db.py
+++ b/neutron/db/vlantransparent_db.py
@@ -17,13 +17,13 @@ from neutron.db import _resource_extend as resource_extend
 from neutron.extensions import vlantransparent
 
 
+@resource_extend.has_resource_extenders
 class Vlantransparent_db_mixin(object):
     """Mixin class to add vlan transparent methods to db_base_plugin_v2."""
 
-    def _extend_network_dict_vlan_transparent(self, network_res, network_db):
+    @staticmethod
+    @resource_extend.extends([attributes.NETWORKS])
+    def _extend_network_dict_vlan_transparent(network_res, network_db):
         network_res[vlantransparent.VLANTRANSPARENT] = (
             network_db.vlan_transparent)
         return network_res
-
-    resource_extend.register_funcs(
-        attributes.NETWORKS, ['_extend_network_dict_vlan_transparent'])
diff --git a/neutron/plugins/ml2/plugin.py b/neutron/plugins/ml2/plugin.py
index d18a9cf6eef..9d64d924735 100644
--- a/neutron/plugins/ml2/plugin.py
+++ b/neutron/plugins/ml2/plugin.py
@@ -109,6 +109,7 @@ def _ml2_port_result_filter_hook(query, filters):
     return query.filter(models_v2.Port.port_binding.has(bind_criteria))
 
 
+@resource_extend.has_resource_extenders
 @registry.has_registry_receivers
 class Ml2Plugin(db_base_plugin_v2.NeutronDbPluginV2,
                 dvr_mac_db.DVRDbMixin,
@@ -602,34 +603,37 @@ class Ml2Plugin(db_base_plugin_v2.NeutronDbPluginV2,
                            'port': binding.port_id})
         return {}
 
-    def _ml2_extend_port_dict_binding(self, port_res, port_db):
+    @staticmethod
+    @resource_extend.extends([attributes.PORTS])
+    def _ml2_extend_port_dict_binding(port_res, port_db):
+        plugin = directory.get_plugin()
         # None when called during unit tests for other plugins.
         if port_db.port_binding:
-            self._update_port_dict_binding(port_res, port_db.port_binding)
-
-    resource_extend.register_funcs(
-        attributes.PORTS, ['_ml2_extend_port_dict_binding'])
+            plugin._update_port_dict_binding(port_res, port_db.port_binding)
 
     # ML2's resource extend functions allow extension drivers that extend
     # attributes for the resources to add those attributes to the result.
-    resource_extend.register_funcs(
-               attributes.NETWORKS, ['_ml2_md_extend_network_dict'])
-    resource_extend.register_funcs(
-               attributes.PORTS, ['_ml2_md_extend_port_dict'])
-    resource_extend.register_funcs(
-               attributes.SUBNETS, ['_ml2_md_extend_subnet_dict'])
 
-    def _ml2_md_extend_network_dict(self, result, netdb):
-        session = self._object_session_or_new_session(netdb)
-        self.extension_manager.extend_network_dict(session, netdb, result)
+    @staticmethod
+    @resource_extend.extends([attributes.NETWORKS])
+    def _ml2_md_extend_network_dict(result, netdb):
+        plugin = directory.get_plugin()
+        session = plugin._object_session_or_new_session(netdb)
+        plugin.extension_manager.extend_network_dict(session, netdb, result)
 
-    def _ml2_md_extend_port_dict(self, result, portdb):
-        session = self._object_session_or_new_session(portdb)
-        self.extension_manager.extend_port_dict(session, portdb, result)
+    @staticmethod
+    @resource_extend.extends([attributes.PORTS])
+    def _ml2_md_extend_port_dict(result, portdb):
+        plugin = directory.get_plugin()
+        session = plugin._object_session_or_new_session(portdb)
+        plugin.extension_manager.extend_port_dict(session, portdb, result)
 
-    def _ml2_md_extend_subnet_dict(self, result, subnetdb):
-        session = self._object_session_or_new_session(subnetdb)
-        self.extension_manager.extend_subnet_dict(session, subnetdb, result)
+    @staticmethod
+    @resource_extend.extends([attributes.SUBNETS])
+    def _ml2_md_extend_subnet_dict(result, subnetdb):
+        plugin = directory.get_plugin()
+        session = plugin._object_session_or_new_session(subnetdb)
+        plugin.extension_manager.extend_subnet_dict(session, subnetdb, result)
 
     @staticmethod
     def _object_session_or_new_session(sql_obj):
diff --git a/neutron/services/auto_allocate/db.py b/neutron/services/auto_allocate/db.py
index 40f6942be67..099544f9ae3 100644
--- a/neutron/services/auto_allocate/db.py
+++ b/neutron/services/auto_allocate/db.py
@@ -42,13 +42,6 @@ IS_DEFAULT = 'is_default'
 CHECK_REQUIREMENTS = 'dry-run'
 
 
-def _extend_external_network_default(core_plugin, net_res, net_db):
-    """Add is_default field to 'show' response."""
-    if net_db.external is not None:
-        net_res[IS_DEFAULT] = net_db.external.is_default
-    return net_res
-
-
 @db_api.retry_if_session_inactive()
 def _ensure_external_network_default_value_callback(
     resource, event, trigger, context, request, network, **kwargs):
@@ -78,11 +71,9 @@ def _ensure_external_network_default_value_callback(
         obj.update()
 
 
+@resource_extend.has_resource_extenders
 class AutoAllocatedTopologyMixin(common_db_mixin.CommonDbMixin):
 
-    resource_extend.register_funcs(
-        attributes.NETWORKS, [_extend_external_network_default])
-
     def __new__(cls, *args, **kwargs):
         # NOTE(kevinbenton): we subscribe on object construction because
         # the tests blow away the callback manager for each run
@@ -116,6 +107,14 @@ class AutoAllocatedTopologyMixin(common_db_mixin.CommonDbMixin):
             self._l3_plugin = directory.get_plugin(constants.L3)
         return self._l3_plugin
 
+    @staticmethod
+    @resource_extend.extends([attributes.NETWORKS])
+    def _extend_external_network_default(net_res, net_db):
+        """Add is_default field to 'show' response."""
+        if net_db.external is not None:
+            net_res[IS_DEFAULT] = net_db.external.is_default
+        return net_res
+
     def get_auto_allocated_topology(self, context, tenant_id, fields=None):
         """Return tenant's network associated to auto-allocated topology.
 
diff --git a/neutron/services/l3_router/l3_router_plugin.py b/neutron/services/l3_router/l3_router_plugin.py
index c2ab0a69a71..cbf893aff33 100644
--- a/neutron/services/l3_router/l3_router_plugin.py
+++ b/neutron/services/l3_router/l3_router_plugin.py
@@ -51,6 +51,7 @@ def disable_dvr_extension_by_config(aliases):
             aliases.remove('dvr')
 
 
+@resource_extend.has_resource_extenders
 class L3RouterPlugin(service_base.ServicePluginBase,
                      common_db_mixin.CommonDbMixin,
                      extraroute_db.ExtraRoute_db_mixin,
@@ -141,10 +142,7 @@ class L3RouterPlugin(service_base.ServicePluginBase,
             context, floatingip,
             initial_status=n_const.FLOATINGIP_STATUS_DOWN)
 
-
-def add_flavor_id(plugin, router_res, router_db):
-    router_res['flavor_id'] = router_db['flavor_id']
-
-
-resource_extend.register_funcs(
-    l3.ROUTERS, [add_flavor_id])
+    @staticmethod
+    @resource_extend.extends([l3.ROUTERS])
+    def add_flavor_id(router_res, router_db):
+        router_res['flavor_id'] = router_db['flavor_id']
diff --git a/neutron/services/revisions/revision_plugin.py b/neutron/services/revisions/revision_plugin.py
index 8a3bda06d8f..4aa9fa358b0 100644
--- a/neutron/services/revisions/revision_plugin.py
+++ b/neutron/services/revisions/revision_plugin.py
@@ -25,6 +25,7 @@ from neutron.db import standard_attr
 LOG = logging.getLogger(__name__)
 
 
+@resource_extend.has_resource_extenders
 class RevisionPlugin(service_base.ServicePluginBase):
     """Plugin to populate revision numbers into standard attr resources."""
 
@@ -32,9 +33,6 @@ class RevisionPlugin(service_base.ServicePluginBase):
 
     def __init__(self):
         super(RevisionPlugin, self).__init__()
-        for resource in standard_attr.get_standard_attr_resource_model_map():
-            resource_extend.register_funcs(
-                resource, [self.extend_resource_dict_revision])
         db_api.sqla_listen(se.Session, 'before_flush', self.bump_revisions)
 
     def bump_revisions(self, session, context, instances):
@@ -76,7 +74,10 @@ class RevisionPlugin(service_base.ServicePluginBase):
     def get_plugin_description(self):
         return "Adds revision numbers to resources."
 
-    def extend_resource_dict_revision(self, plugin, resource_res, resource_db):
+    @staticmethod
+    @resource_extend.extends(
+        list(standard_attr.get_standard_attr_resource_model_map()))
+    def extend_resource_dict_revision(resource_res, resource_db):
         resource_res['revision_number'] = resource_db.revision_number
 
     def _find_related_obj(self, session, obj, relationship_col):
diff --git a/neutron/services/segments/plugin.py b/neutron/services/segments/plugin.py
index b4167553c11..4734225dd15 100644
--- a/neutron/services/segments/plugin.py
+++ b/neutron/services/segments/plugin.py
@@ -49,30 +49,7 @@ SEGMENT_NAME_STUB = 'Neutron segment id %s'
 MAX_INVENTORY_UPDATE_RETRIES = 10
 
 
-def _extend_network_dict_binding(plugin, network_res, network_db):
-    if not directory.get_plugin('segments'):
-        return
-
-    # TODO(carl_baldwin) Make this work with service subnets when it's a thing.
-    is_adjacent = (not network_db.subnets
-                   or not network_db.subnets[0].segment_id)
-    network_res[l2_adjacency.L2_ADJACENCY] = is_adjacent
-
-
-def _extend_subnet_dict_binding(plugin, subnet_res, subnet_db):
-    subnet_res['segment_id'] = subnet_db.get('segment_id')
-
-
-def _extend_port_dict_binding(plugin, port_res, port_db):
-    if not directory.get_plugin('segments'):
-        return
-
-    value = ip_allocation.IP_ALLOCATION_IMMEDIATE
-    if port_db.get('ip_allocation'):
-        value = port_db.get('ip_allocation')
-    port_res[ip_allocation.IP_ALLOCATION] = value
-
-
+@resource_extend.has_resource_extenders
 @registry.has_registry_receivers
 class Plugin(db.SegmentDbMixin, segment.SegmentPluginBase):
 
@@ -81,14 +58,36 @@ class Plugin(db.SegmentDbMixin, segment.SegmentPluginBase):
     supported_extension_aliases = ["segment", "ip_allocation", "l2_adjacency"]
 
     def __init__(self):
-        resource_extend.register_funcs(
-            attributes.NETWORKS, [_extend_network_dict_binding])
-        resource_extend.register_funcs(
-            attributes.SUBNETS, [_extend_subnet_dict_binding])
-        resource_extend.register_funcs(
-            attributes.PORTS, [_extend_port_dict_binding])
         self.nova_updater = NovaSegmentNotifier()
 
+    @staticmethod
+    @resource_extend.extends([attributes.NETWORKS])
+    def _extend_network_dict_binding(network_res, network_db):
+        if not directory.get_plugin('segments'):
+            return
+
+        # TODO(carl_baldwin) Make this work with service subnets when
+        #                    it's a thing.
+        is_adjacent = (not network_db.subnets
+                       or not network_db.subnets[0].segment_id)
+        network_res[l2_adjacency.L2_ADJACENCY] = is_adjacent
+
+    @staticmethod
+    @resource_extend.extends([attributes.SUBNETS])
+    def _extend_subnet_dict_binding(subnet_res, subnet_db):
+        subnet_res['segment_id'] = subnet_db.get('segment_id')
+
+    @staticmethod
+    @resource_extend.extends([attributes.PORTS])
+    def _extend_port_dict_binding(port_res, port_db):
+        if not directory.get_plugin('segments'):
+            return
+
+        value = ip_allocation.IP_ALLOCATION_IMMEDIATE
+        if port_db.get('ip_allocation'):
+            value = port_db.get('ip_allocation')
+        port_res[ip_allocation.IP_ALLOCATION] = value
+
     @classmethod
     def get_instance(cls):
         if cls._instance is None:
diff --git a/neutron/services/tag/tag_plugin.py b/neutron/services/tag/tag_plugin.py
index b7978e717d1..b81e1331e94 100644
--- a/neutron/services/tag/tag_plugin.py
+++ b/neutron/services/tag/tag_plugin.py
@@ -44,13 +44,7 @@ resource_model_map = {
 }
 
 
-def _extend_tags_dict(plugin, response_data, db_data):
-    if not directory.get_plugin(tag_ext.TAG_PLUGIN_TYPE):
-        return
-    tags = [tag_db.tag for tag_db in db_data.standard_attr.tags]
-    response_data['tags'] = tags
-
-
+@resource_extend.has_resource_extenders
 class TagPlugin(common_db_mixin.CommonDbMixin, tag_ext.TagPluginBase):
     """Implementation of the Neutron Tag Service Plugin."""
 
@@ -59,8 +53,7 @@ class TagPlugin(common_db_mixin.CommonDbMixin, tag_ext.TagPluginBase):
     def __new__(cls, *args, **kwargs):
         inst = super(TagPlugin, cls).__new__(cls, *args, **kwargs)
         inst._filter_methods = []  # prevent GC of our partial functions
-        for resource, model in resource_model_map.items():
-            resource_extend.register_funcs(resource, [_extend_tags_dict])
+        for model in resource_model_map.values():
             method = functools.partial(tag_methods.apply_tag_filters, model)
             inst._filter_methods.append(method)
             model_query.register_hook(model, "tag",
@@ -69,6 +62,14 @@ class TagPlugin(common_db_mixin.CommonDbMixin, tag_ext.TagPluginBase):
                                       result_filters=method)
         return inst
 
+    @staticmethod
+    @resource_extend.extends(list(resource_model_map))
+    def _extend_tags_dict(response_data, db_data):
+        if not directory.get_plugin(tag_ext.TAG_PLUGIN_TYPE):
+            return
+        tags = [tag_db.tag for tag_db in db_data.standard_attr.tags]
+        response_data['tags'] = tags
+
     def _get_resource(self, context, resource, resource_id):
         model = resource_model_map[resource]
         try:
diff --git a/neutron/services/timestamp/timestamp_db.py b/neutron/services/timestamp/timestamp_db.py
index fc93768f3a8..d1602939807 100644
--- a/neutron/services/timestamp/timestamp_db.py
+++ b/neutron/services/timestamp/timestamp_db.py
@@ -70,12 +70,6 @@ def _format_timestamp(resource_db, result):
                             strftime(TIME_FORMAT_WHOLE_SECONDS)) + 'Z'
 
 
-def _extend_resource_dict_timestamp(plugin_obj, resource_res, resource_db):
-    if (resource_db and resource_db.created_at and
-            resource_db.updated_at):
-        _format_timestamp(resource_db, resource_res)
-
-
 def _add_timestamp(mapper, _conn, target):
     if not target.created_at and not target.updated_at:
         time = timeutils.utcnow()
@@ -84,14 +78,13 @@ def _add_timestamp(mapper, _conn, target):
     return target
 
 
+@resource_extend.has_resource_extenders
 class TimeStamp_db_mixin(object):
     """Mixin class to add Time Stamp methods."""
 
     def __new__(cls, *args, **kwargs):
         rs_model_maps = standard_attr.get_standard_attr_resource_model_map()
-        for rsmap, model in rs_model_maps.items():
-            resource_extend.register_funcs(
-                rsmap, [_extend_resource_dict_timestamp])
+        for model in rs_model_maps.values():
             model_query.register_hook(
                 model,
                 "change_since_query",
@@ -105,3 +98,11 @@ class TimeStamp_db_mixin(object):
         listen(standard_attr.StandardAttribute, 'before_insert',
                _add_timestamp)
         listen(se.Session, 'before_flush', _update_timestamp)
+
+    @staticmethod
+    @resource_extend.extends(
+        list(standard_attr.get_standard_attr_resource_model_map()))
+    def _extend_resource_dict_timestamp(resource_res, resource_db):
+        if (resource_db and resource_db.created_at and
+                resource_db.updated_at):
+            _format_timestamp(resource_db, resource_res)
diff --git a/neutron/services/trunk/plugin.py b/neutron/services/trunk/plugin.py
index 75e57eef0e9..8710e862c85 100644
--- a/neutron/services/trunk/plugin.py
+++ b/neutron/services/trunk/plugin.py
@@ -16,6 +16,7 @@ import copy
 
 from neutron_lib.api.definitions import portbindings
 from neutron_lib import context
+from neutron_lib.plugins import directory
 from neutron_lib.services import base as service_base
 from oslo_log import log as logging
 from oslo_utils import uuidutils
@@ -40,26 +41,7 @@ from neutron.services.trunk.seg_types import validators
 LOG = logging.getLogger(__name__)
 
 
-def _extend_port_trunk_details(core_plugin, port_res, port_db):
-    """Add trunk details to a port."""
-    if port_db.trunk_port:
-        subports = {
-            x.port_id: {'segmentation_id': x.segmentation_id,
-                        'segmentation_type': x.segmentation_type,
-                        'port_id': x.port_id}
-            for x in port_db.trunk_port.sub_ports
-        }
-        ports = core_plugin.get_ports(
-            context.get_admin_context(), filters={'id': subports})
-        for port in ports:
-            subports[port['id']]['mac_address'] = port['mac_address']
-        trunk_details = {'trunk_id': port_db.trunk_port.id,
-                         'sub_ports': [x for x in subports.values()]}
-        port_res['trunk_details'] = trunk_details
-
-    return port_res
-
-
+@resource_extend.has_resource_extenders
 @registry.has_registry_receivers
 class TrunkPlugin(service_base.ServicePluginBase,
                   common_db_mixin.CommonDbMixin):
@@ -70,8 +52,6 @@ class TrunkPlugin(service_base.ServicePluginBase,
     __native_sorting_support = True
 
     def __init__(self):
-        resource_extend.register_funcs(
-            attributes.PORTS, [_extend_port_trunk_details])
         self._rpc_backend = None
         self._drivers = []
         self._segmentation_types = {}
@@ -85,6 +65,28 @@ class TrunkPlugin(service_base.ServicePluginBase,
             LOG.debug('Trunk plugin loaded with driver %s', driver.name)
         self.check_compatibility()
 
+    @staticmethod
+    @resource_extend.extends([attributes.PORTS])
+    def _extend_port_trunk_details(port_res, port_db):
+        """Add trunk details to a port."""
+        if port_db.trunk_port:
+            subports = {
+                x.port_id: {'segmentation_id': x.segmentation_id,
+                            'segmentation_type': x.segmentation_type,
+                            'port_id': x.port_id}
+                for x in port_db.trunk_port.sub_ports
+            }
+            core_plugin = directory.get_plugin()
+            ports = core_plugin.get_ports(
+                context.get_admin_context(), filters={'id': subports})
+            for port in ports:
+                subports[port['id']]['mac_address'] = port['mac_address']
+            trunk_details = {'trunk_id': port_db.trunk_port.id,
+                             'sub_ports': [x for x in subports.values()]}
+            port_res['trunk_details'] = trunk_details
+
+        return port_res
+
     def check_compatibility(self):
         """Verify the plugin can load correctly and fail otherwise."""
         self.check_driver_compatibility()
diff --git a/neutron/tests/base.py b/neutron/tests/base.py
index 944c4fc66f5..4a4afcb3665 100644
--- a/neutron/tests/base.py
+++ b/neutron/tests/base.py
@@ -46,6 +46,7 @@ from neutron.callbacks import manager as registry_manager
 from neutron.common import config
 from neutron.common import rpc as n_rpc
 from neutron.db import _model_query as model_query
+from neutron.db import _resource_extend as resource_extend
 from neutron.db import agentschedulers_db
 from neutron.db import api as db_api
 from neutron import manager
@@ -167,6 +168,7 @@ class DietTestCase(base.BaseTestCase):
         self.addCleanup(mock.patch.stopall)
 
         self.addCleanup(self.reset_model_query_hooks)
+        self.addCleanup(self.reset_resource_extend_functions)
 
         self.addOnException(self.check_for_systemexit)
         self.orig_pid = os.getpid()
@@ -177,6 +179,10 @@ class DietTestCase(base.BaseTestCase):
     def reset_model_query_hooks():
         model_query._model_query_hooks = {}
 
+    @staticmethod
+    def reset_resource_extend_functions():
+        resource_extend._resource_extend_functions = {}
+
     def addOnException(self, handler):
 
         def safe_handler(*args, **kwargs):
diff --git a/neutron/tests/functional/scheduler/test_l3_agent_scheduler.py b/neutron/tests/functional/scheduler/test_l3_agent_scheduler.py
index 9231b8285cb..262ac8481f7 100644
--- a/neutron/tests/functional/scheduler/test_l3_agent_scheduler.py
+++ b/neutron/tests/functional/scheduler/test_l3_agent_scheduler.py
@@ -18,6 +18,7 @@ import random
 
 from neutron_lib import constants
 from neutron_lib import context
+from neutron_lib.plugins import directory
 from oslo_utils import uuidutils
 import testscenarios
 
@@ -45,6 +46,7 @@ class L3SchedulerBaseTest(test_db_base_plugin_v2.NeutronDbPluginV2TestCase):
         super(L3SchedulerBaseTest, self).setUp(PLUGIN_NAME)
 
         self.l3_plugin = l3_router_plugin.L3RouterPlugin()
+        directory.add_plugin(constants.L3, self.l3_plugin)
         self.adminContext = context.get_admin_context()
         self.adminContext.tenant_id = _uuid()
 
@@ -296,6 +298,7 @@ class L3AZSchedulerBaseTest(test_db_base_plugin_v2.NeutronDbPluginV2TestCase):
         super(L3AZSchedulerBaseTest, self).setUp(plugin='ml2')
 
         self.l3_plugin = l3_router_plugin.L3RouterPlugin()
+        directory.add_plugin(constants.L3, self.l3_plugin)
         self.l3_plugin.router_scheduler = None
         self.adminContext = context.get_admin_context()
         self.adminContext.tenant_id = '_func_test_tenant_'
diff --git a/neutron/tests/unit/db/test_l3_dvr_db.py b/neutron/tests/unit/db/test_l3_dvr_db.py
index 8d8a7b7b917..23461e2d4b6 100644
--- a/neutron/tests/unit/db/test_l3_dvr_db.py
+++ b/neutron/tests/unit/db/test_l3_dvr_db.py
@@ -48,6 +48,7 @@ class L3DvrTestCase(test_db_base_plugin_v2.NeutronDbPluginV2TestCase):
         self.core_plugin = directory.get_plugin()
         self.ctx = context.get_admin_context()
         self.mixin = FakeL3Plugin()
+        directory.add_plugin(const.L3, self.mixin)
 
     def _create_router(self, router):
         with self.ctx.session.begin(subtransactions=True):
diff --git a/neutron/tests/unit/db/test_portsecurity_db.py b/neutron/tests/unit/db/test_portsecurity_db.py
index 5ed483070f1..e164cc5be91 100644
--- a/neutron/tests/unit/db/test_portsecurity_db.py
+++ b/neutron/tests/unit/db/test_portsecurity_db.py
@@ -11,6 +11,8 @@
 #    under the License.
 
 import mock
+from neutron_lib import constants
+from neutron_lib.plugins import directory
 
 from neutron.db import portsecurity_db as pd
 from neutron.db import portsecurity_db_common as pdc
@@ -29,6 +31,7 @@ class PortSecurityDbMixinTestCase(base.BaseTestCase):
     def setUp(self):
         super(PortSecurityDbMixinTestCase, self).setUp()
         self.plugin = FakePlugin()
+        directory.add_plugin(constants.CORE, self.plugin)
 
     @mock.patch.object(common, '_extend_port_security_dict')
     def test__extend_port_security_dict_relies_on_common(self, extend):
diff --git a/neutron/tests/unit/extensions/test_data_plane_status.py b/neutron/tests/unit/extensions/test_data_plane_status.py
index 40ceb8ebcf4..edbc0a0fa3c 100644
--- a/neutron/tests/unit/extensions/test_data_plane_status.py
+++ b/neutron/tests/unit/extensions/test_data_plane_status.py
@@ -41,11 +41,18 @@ class DataPlaneStatusTestExtensionManager(object):
         return dps_ext.Data_plane_status.get_extended_resources(version)
 
 
+@resource_extend.has_resource_extenders
 class DataPlaneStatusExtensionTestPlugin(db_base_plugin_v2.NeutronDbPluginV2,
                                          dps_db.DataPlaneStatusMixin):
 
     supported_extension_aliases = ["data-plane-status"]
 
+    @staticmethod
+    @resource_extend.extends([attrs.PORTS])
+    def _extend_port_data_plane_status(port_res, port_db):
+        return dps_db.DataPlaneStatusMixin._extend_port_data_plane_status(
+            port_res, port_db)
+
     def update_port(self, context, id, port):
         with context.session.begin(subtransactions=True):
             ret_port = super(DataPlaneStatusExtensionTestPlugin,
@@ -56,9 +63,6 @@ class DataPlaneStatusExtensionTestPlugin(db_base_plugin_v2.NeutronDbPluginV2,
                                                             ret_port)
         return ret_port
 
-    resource_extend.register_funcs(attrs.PORTS,
-                                   ['_extend_port_data_plane_status'])
-
 
 class DataPlaneStatusExtensionTestCase(
     test_db_base_plugin_v2.NeutronDbPluginV2TestCase):
diff --git a/neutron/tests/unit/extensions/test_l3.py b/neutron/tests/unit/extensions/test_l3.py
index ca54850d665..b08d0544dae 100644
--- a/neutron/tests/unit/extensions/test_l3.py
+++ b/neutron/tests/unit/extensions/test_l3.py
@@ -571,6 +571,7 @@ class ExtraAttributesMixinTestCase(testlib_api.SqlTestCase):
     def setUp(self):
         super(ExtraAttributesMixinTestCase, self).setUp()
         self.mixin = l3_attrs_db.ExtraAttributesMixin()
+        directory.add_plugin(lib_constants.L3, self.mixin)
         self.ctx = context.get_admin_context()
         self.router = l3_models.Router()
         with self.ctx.session.begin():
diff --git a/neutron/tests/unit/extensions/test_subnet_service_types.py b/neutron/tests/unit/extensions/test_subnet_service_types.py
index 59e421ff33f..fd86c081b05 100644
--- a/neutron/tests/unit/extensions/test_subnet_service_types.py
+++ b/neutron/tests/unit/extensions/test_subnet_service_types.py
@@ -13,6 +13,7 @@
 import webob.exc
 
 from neutron.db import db_base_plugin_v2
+from neutron.db import subnet_service_type_db_models
 from neutron.extensions import subnet_service_types
 from neutron.tests.unit.db import test_db_base_plugin_v2
 
@@ -34,7 +35,8 @@ class SubnetServiceTypesExtensionManager(object):
 
 
 class SubnetServiceTypesExtensionTestPlugin(
-        db_base_plugin_v2.NeutronDbPluginV2):
+        db_base_plugin_v2.NeutronDbPluginV2,
+        subnet_service_type_db_models.SubnetServiceTypeMixin):
     """Test plugin to mixin the subnet service_types extension.
     """