From: armando-migliaccio <amigliaccio@nicira.com>
Date: Sat, 28 Sep 2013 01:38:16 +0000 (-0700)
Subject: Avoid dhcp agent race condition on subnet and network delete
X-Git-Url: https://review.fuel-infra.org/gitweb?a=commitdiff_plain;h=ffa11a64706e898ba3ae45f84920d632b5947add;p=openstack-build%2Fneutron-build.git

Avoid dhcp agent race condition on subnet and network delete

This patch ensures that, when the dhcp agent queries the server
to retrieve and delete its DHCP port, it does so by selecting
for update. This has been done by introducing a new method
that combines the get and delete in one shot.

Closes-Bug:1197627

Change-Id: I1e8a87d7dc1a1cb9309aeefd41619e20f49f95a6
---

diff --git a/neutron/db/db_base_plugin_v2.py b/neutron/db/db_base_plugin_v2.py
index 52fc45389..f7b0442f0 100644
--- a/neutron/db/db_base_plugin_v2.py
+++ b/neutron/db/db_base_plugin_v2.py
@@ -1402,6 +1402,14 @@ class NeutronDbPluginV2(neutron_plugin_base_v2.NeutronPluginBaseV2,
         with context.session.begin(subtransactions=True):
             self._delete_port(context, id)
 
+    def delete_ports(self, context, filters):
+        with context.session.begin(subtransactions=True):
+            ports = self._get_ports_query(
+                context, filters=filters).with_lockmode('update')
+            if ports:
+                for port in ports:
+                    self.delete_port(context, port['id'])
+
     def _delete_port(self, context, id):
         port = self._get_port(context, id)
 
diff --git a/neutron/db/dhcp_rpc_base.py b/neutron/db/dhcp_rpc_base.py
index a8a2b4bf2..2eacbbff4 100644
--- a/neutron/db/dhcp_rpc_base.py
+++ b/neutron/db/dhcp_rpc_base.py
@@ -179,10 +179,7 @@ class DhcpRpcCallbackMixin(object):
                   {'network_id': network_id, 'host': host})
         plugin = manager.NeutronManager.get_plugin()
         filters = dict(network_id=[network_id], device_id=[device_id])
-        ports = plugin.get_ports(context, filters=filters)
-
-        if ports:
-            plugin.delete_port(context, ports[0]['id'])
+        plugin.delete_ports(context, filters=filters)
 
     def release_port_fixed_ip(self, context, **kwargs):
         """Release the fixed_ip associated the subnet on a port."""
diff --git a/neutron/tests/unit/test_db_rpc_base.py b/neutron/tests/unit/test_db_rpc_base.py
index 9be906529..e878f0936 100644
--- a/neutron/tests/unit/test_db_rpc_base.py
+++ b/neutron/tests/unit/test_db_rpc_base.py
@@ -131,9 +131,9 @@ class TestDhcpRpcCallackMixin(base.BaseTestCase):
                                          device_id='devid')
 
         self.plugin.assert_has_calls([
-            mock.call.get_ports(mock.ANY, filters=dict(network_id=['netid'],
-                                                       device_id=['devid'])),
-            mock.call.delete_port(mock.ANY, 'port_id')])
+            mock.call.delete_ports(mock.ANY,
+                                   filters=dict(network_id=['netid'],
+                                                device_id=['devid']))])
 
     def test_release_port_fixed_ip(self):
         port_retval = dict(id='port_id', fixed_ips=[dict(subnet_id='a')])