Merge "Build socket list right before select call"

ironic_python_agent/netutils.py

@@ -162,13 +162,12 @@ def _get_lldp_info(interfaces):
     if not interfaces:
         return {}
 
-    socks = [interface[1] for interface in interfaces]
-
     while interfaces:
         LOG.info('Waiting on LLDP info for interfaces: %(interfaces)s, '
                  'timeout: %(timeout)s', {'interfaces': interfaces,
                                           'timeout': CONF.lldp_timeout})
 
+        socks = [interface[1] for interface in interfaces]
         # rlist is a list of sockets ready for reading
         rlist, _, _ = select.select(socks, [], [], CONF.lldp_timeout)
         if not rlist:

ironic_python_agent/tests/unit/test_netutils.py

@@ -113,7 +113,8 @@ class TestNetutils(test_base.BaseTestCase):
         sock_mock.side_effect = [sock1, sock2]
 
         select_mock.side_effect = [
-            ([sock1, sock2], [], []),
+            ([sock1], [], []),
+            ([sock2], [], []),
         ]
 
         lldp_info = netutils.get_lldp_info(interface_names)
@@ -131,6 +132,12 @@ class TestNetutils(test_base.BaseTestCase):
         # 2 interfaces, 2 calls to enter promiscuous mode, 1 to leave
         self.assertEqual(6, fcntl_mock.call_count)
 
+        expected_calls = [
+            mock.call([sock1, sock2], [], [], cfg.CONF.lldp_timeout),
+            mock.call([sock2], [], [], cfg.CONF.lldp_timeout),
+        ]
+        self.assertEqual(expected_calls, select_mock.call_args_list)
+
     @mock.patch('fcntl.ioctl')
     @mock.patch('select.select')
     @mock.patch('socket.socket')

releasenotes/notes/lldp-loop-fdfa584caf33d847.yaml

@@ -0,0 +1,4 @@
+---
+fixes:
+  - Fixed incorrect invocation of "select" which could cause LLDP collection
+    to hang under certain conditions.