VMware: fix bug for exceptions thrown in _wait_for_task

If the _call_method fails, for example a resource is not found,
then the same call will be invoked again due to the fact that the
polling task was not stopped.

Closes-Bug: #1246848

Change-Id: If4818e41aed5be03395ab22afc0edf9abb3c34e1
(cherry picked from commit 1c1570f)

nova/tests/virt/vmwareapi/test_vmwareapi.py

@@ -241,6 +241,32 @@ def _fake_login(_self):
         self.conn = driver.VMwareAPISession()
         self.assertEqual(self.attempts, 2)
 
+    def test_wait_for_task_exception(self):
+        self.flags(task_poll_interval=1, group='vmware')
+        self.login_session = vmwareapi_fake.FakeVim()._login()
+        self.stop_called = 0
+
+        def _fake_login(_self):
+            return self.login_session
+
+        self.stubs.Set(vmwareapi_fake.FakeVim, '_login', _fake_login)
+
+        def fake_poll_task(instance_uuid, task_ref, done):
+            done.send_exception(exception.NovaException('fake exception'))
+
+        def fake_stop_loop(loop):
+            self.stop_called += 1
+            return loop.stop()
+
+        self.conn = driver.VMwareAPISession()
+        self.stubs.Set(self.conn, "_poll_task",
+                       fake_poll_task)
+        self.stubs.Set(self.conn, "_stop_loop",
+                       fake_stop_loop)
+        self.assertRaises(exception.NovaException,
+                          self.conn._wait_for_task, 'fake-id', 'fake-ref')
+        self.assertEqual(self.stop_called, 1)
+
     def _create_instance_in_the_db(self, node=None, set_image_ref=True,
                                    uuid=None):
         if not node:

nova/virt/vmwareapi/driver.py

@@ -910,6 +910,9 @@ def _get_vim(self):
             self._create_session()
         return self.vim
 
+    def _stop_loop(self, loop):
+        loop.stop()
+
     def _wait_for_task(self, instance_uuid, task_ref):
         """
         Return a Deferred that will give the result of the given task.
@@ -920,8 +923,12 @@ def _wait_for_task(self, instance_uuid, task_ref):
                                                     instance_uuid,
                                                     task_ref, done)
         loop.start(CONF.vmware.task_poll_interval)
-        ret_val = done.wait()
-        loop.stop()
+        try:
+            ret_val = done.wait()
+        except Exception:
+            raise
+        finally:
+            self._stop_loop(loop)
         return ret_val
 
     def _poll_task(self, instance_uuid, task_ref, done):