From f48adb004b1a9b929f540e85a2a55ab461f689aa Mon Sep 17 00:00:00 2001
From: Gary Kotton <gkotton@vmware.com>
Date: Sun, 18 Dec 2016 21:46:05 +0200
Subject: [PATCH] Directory: fix concurreny issue

If more than one thread would call _get_plugin_directory at the
same time and there was no plugin created then this may lead to
a race and each thread may have a different list of plugin data.

Change-Id: Id5d23f06e5f59fc07b660ef6c23cacf8cde1b999
---
 neutron_lib/plugins/directory.py | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/neutron_lib/plugins/directory.py b/neutron_lib/plugins/directory.py
index 22840b3..4ea743b 100644
--- a/neutron_lib/plugins/directory.py
+++ b/neutron_lib/plugins/directory.py
@@ -66,7 +66,8 @@ _PLUGIN_DIRECTORY = None
 @_synchronized("plugin-directory")
 def _create_plugin_directory():
     global _PLUGIN_DIRECTORY
-    _PLUGIN_DIRECTORY = _PluginDirectory()
+    if _PLUGIN_DIRECTORY is None:
+        _PLUGIN_DIRECTORY = _PluginDirectory()
     return _PLUGIN_DIRECTORY