Remove exception `IpAddressAllocationNotFound`

This patch removes the ``IpAddressAllocationNotFound`` exception. This
exception was raised when a IPAM register was called to be deleted
but not found.

As reported in the LP bug, this IPAM register deletion can be called
several times if a port fails during the creation. The IPAM register
deletion calls the DB deletion but doesn't raise any exception if the
register does not exist. The code ensures the IPAM register is
deleted and there is no need to fail if it is not present anymore.

This patch also removes the exception catch and try in "update_port",
that was added in [0] as a fix for [1]. That was added because the
subnet deletion code involved a port update call [2] during the
IP allocation deletion, if any port was still present in the subnet.
Since [3], this code is not needed because the subnet deletion does
not call a port update anymore.

[0]https://review.opendev.org/c/openstack/neutron/+/373536
[1]https://bugs.launchpad.net/neutron/+bug/1622616
[2]https://github.com/openstack/neutron/blob/pike-em/neutron/db/db_base_plugin_v2.py#L1017-L1018
[3]https://review.opendev.org/c/openstack/neutron/+/713045

Closes-Bug: #1965807
Related-Bug: #1954763
Related-Bug: #1622616

Change-Id: I5b96b3a91aacffe118ddbb91a75c4892818ba97a

neutron/db/db_base_plugin_v2.py

@@ -1524,13 +1524,6 @@ class NeutronDbPluginV2(db_base_plugin_common.DbBasePluginCommon,
                     old_port_db=db_port,
                     old_port=self._make_port_dict(db_port),
                     new_port=new_port)
-            except ipam_exc.IpAddressAllocationNotFound as e:
-                # If a port update and a subnet delete interleave, there is a
-                # chance that the IPAM update operation raises this exception.
-                # Rather than throwing that up to the user under some sort of
-                # conflict, bubble up a retry instead that should bring things
-                # back to sanity.
-                raise os_db_exc.RetryRequest(e)
             except ipam_exc.IPAddressChangeNotAllowed as e:
                 raise exc.BadRequest(resource='ports', msg=e)
         return self._make_port_dict(db_port)

neutron/ipam/drivers/neutrondb_ipam/driver.py

@@ -281,14 +281,8 @@ class NeutronDbSubnet(ipam_base.Subnet):
     def deallocate(self, address):
         # This is almost a no-op because the Neutron DB IPAM driver does not
         # delete IPAllocation objects at every deallocation. The only
-        # operation it performs is to delete an IPRequest entry.
-        count = self.subnet_manager.delete_allocation(
-            self._context, address)
-        # count can hardly be greater than 1, but it can be 0...
-        if not count:
-            raise ipam_exc.IpAddressAllocationNotFound(
-                subnet_id=self.subnet_manager.neutron_id,
-                ip_address=address)
+        # operation it performs is to delete an IPAMAllocation entry.
+        self.subnet_manager.delete_allocation(self._context, address)
 
     def _no_pool_changes(self, context, pools):
         """Check if pool updates in db are required."""

neutron/ipam/exceptions.py

@@ -31,11 +31,6 @@ class InvalidAddressType(exceptions.NeutronException):
     message = _("Unknown address type %(address_type)s")
 
 
-class IpAddressAllocationNotFound(exceptions.NeutronException):
-    message = _("Unable to find IP address %(ip_address)s on subnet "
-                "%(subnet_id)s")
-
-
 class IpAddressAlreadyAllocated(exceptions.Conflict):
     message = _("IP address %(ip)s already allocated in subnet %(subnet_id)s")
 

neutron/tests/unit/db/test_db_base_plugin_v2.py

@@ -1498,22 +1498,6 @@ fixed_ips=ip_address%%3D%s&fixed_ips=ip_address%%3D%s&fixed_ips=subnet_id%%3D%s
             res = req.get_response(self.api)
             self.assertEqual(webob.exc.HTTPNotFound.code, res.status_int)
 
-    def test_port_update_with_ipam_error(self):
-        with self.network() as network,\
-                self.subnet(), self.subnet(),\
-                self.port(network=network) as port,\
-                mock.patch('neutron.ipam.drivers.neutrondb_ipam.'
-                           'driver.NeutronDbSubnet.deallocate') as f:
-            f.side_effect = [
-                ipam_exc.IpAddressAllocationNotFound(
-                    ip_address='foo_i', subnet_id='foo_s'),
-                None,
-            ]
-            data = {'port': {'name': 'fool-me'}}
-            req = self.new_update_request('ports', data, port['port']['id'])
-            res = self.deserialize(self.fmt, req.get_response(self.api))
-            self.assertEqual('fool-me', res['port']['name'])
-
     def test_update_port(self):
         with self.port() as port:
             data = {'port': {'admin_state_up': False}}

neutron/tests/unit/ipam/drivers/neutrondb_ipam/test_driver.py

@@ -423,12 +423,6 @@ class TestNeutronDbIpamSubnet(testlib_api.SqlTestCase,
         # future proofing in case v6-specific logic will be added.
         self._test_deallocate_address('fde3:abcd:4321:1::/64', 6)
 
-    def test_allocate_unallocated_address_fails(self):
-        ipam_subnet = self._create_and_allocate_ipam_subnet(
-            '10.0.0.0/24', ip_version=constants.IP_VERSION_4)[0]
-        self.assertRaises(ipam_exc.IpAddressAllocationNotFound,
-                          ipam_subnet.deallocate, '10.0.0.2')
-
     def test_allocate_all_pool_addresses_triggers_range_recalculation(self):
         # This test instead might be made to pass, but for the wrong reasons!
         pass