Simulate bug 1969496

As If9ab424cc7375a1f0d41b03f01c4a823216b3eb8 stated there is a way for
the pci_device table to become inconsistent. Parent PF can be in
'available' state while children VFs are still in 'unavailable' state.
In this situation the PF is schedulable but the PCI claim will fail to
when try to mark the dependent VFs unavailable.

This patch adds a test case that shows the error.

Related-Bug: #1969496

Change-Id: I7b432d7a32aeb1ab765d1f731691c7841a8f1440
(cherry picked from commit 9ee5d2c)

Author: gibizer

nova/tests/unit/pci/test_manager.py

@@ -21,6 +21,7 @@
 
 from nova.compute import vm_states
 from nova import context
+from nova import exception
 from nova import objects
 from nova.objects import fields
 from nova.pci import manager
@@ -478,6 +479,61 @@ def test_set_hvdevs_unavailable_pf_removed(self):
         self.assertEqual('allocated', dev4_vf.status)
         self.assertEqual(uuidsentinel.instance1, dev4_vf.instance_uuid)
 
+    def test_claim_available_pf_while_child_vf_is_unavailable(self):
+        # NOTE(gibi): this is bug 1969496. The state created here is
+        # inconsistent and should not happen. But it did happen in some cases
+        # where we were not able to track down the way how it happened.
+
+        # We start with a PF parent and a VF child. The PF is available and
+        # the VF is unavailable.
+        pf = copy.deepcopy(fake_db_dev_3)
+        vf = copy.deepcopy(fake_db_dev_4)
+        vf['status'] = fields.PciDeviceStatus.UNAVAILABLE
+        self._create_tracker([pf, vf])
+
+        pf_dev = self._get_device_by_address(pf['address'])
+        self.assertEqual('available', pf_dev.status)
+        vf_dev = self._get_device_by_address(vf['address'])
+        self.assertEqual('unavailable', vf_dev.status)
+
+        pci_requests_obj = self._create_pci_requests_object(
+            [
+                {
+                    'count': 1,
+                    'spec': [{'dev_type': fields.PciDeviceType.SRIOV_PF}]
+                }
+            ],
+            instance_uuid=uuidsentinel.instance1,
+        )
+        # now try to claim and allocate the PF. It should work as it is
+        # available
+        # This is bug 1969496 as the claim fails with exception
+        ex = self.assertRaises(
+            exception.PciDevicePoolEmpty,
+            self.tracker.claim_instance,
+            mock.sentinel.context,
+            pci_requests_obj,
+            None
+        )
+        self.assertIn(
+            'Attempt to consume PCI device 1:0000:00:02.1 from empty pool',
+            str(ex)
+        )
+        pf_dev = self._get_device_by_address(pf['address'])
+        self.assertEqual('available', pf_dev.status)
+        vf_dev = self._get_device_by_address(vf['address'])
+        self.assertEqual('unavailable', vf_dev.status)
+
+        # This should work when the bug is fixed
+        # self.tracker.claim_instance(
+        #     mock.sentinel.context, pci_requests_obj, None)
+        # self.tracker.allocate_instance({'uuid': uuidsentinel.instance1})
+
+        # pf_dev = self._get_device_by_address(pf['address'])
+        # self.assertEqual('allocated', pf_dev.status)
+        # vf_dev = self._get_device_by_address(vf['address'])
+        # self.assertEqual('unavailable', vf_dev.status)
+
     def test_update_pci_for_instance_active(self):
         pci_requests_obj = self._create_pci_requests_object(fake_pci_requests)
         self.tracker.claim_instance(mock.sentinel.context,