From fef371a425d603e184f22d3b630b2c3bd27c7cae Mon Sep 17 00:00:00 2001
From: Balazs Gibizer <balazs.gibizer@est.tech>
Date: Tue, 23 Feb 2021 15:02:06 +0100
Subject: [PATCH] Follow up for QoS interface attach

This patch fixes minor comments from
Id4684093e8bdf3b61667490443e3d2f6ed65f4b3

Change-Id: I6e70e24d837b6f194972386a32ad757ce25dcee0
Blueprint: support-interface-attach-with-qos-ports
---
 nova/compute/manager.py               |  7 +++++++
 nova/scheduler/client/report.py       |  4 +++-
 nova/tests/functional/test_servers.py | 16 +++++++++++++---
 3 files changed, 23 insertions(+), 4 deletions(-)

diff --git a/nova/compute/manager.py b/nova/compute/manager.py
index a78bbdfc450c..0beedeea9de7 100644
--- a/nova/compute/manager.py
+++ b/nova/compute/manager.py
@@ -7602,6 +7602,13 @@ class ComputeManager(manager.Manager):
         if not request_groups:
             return None, None
 
+        # NOTE(gibi): we assume a single RequestGroup here as:
+        # 1) there can only be a single port per interface attach request
+        # 2) a single port can only request resources in a single RequestGroup
+        #    as per the current neutron API.
+        # #2) might change in the future so both
+        # nova.network.neutron.API.create_resource_requests() and this function
+        # takes a list of groups
         request_group = request_groups[0]
 
         # restrict the resource request to the current compute node. The
diff --git a/nova/scheduler/client/report.py b/nova/scheduler/client/report.py
index da195bdc112e..95682e2d2061 100644
--- a/nova/scheduler/client/report.py
+++ b/nova/scheduler/client/report.py
@@ -1755,7 +1755,9 @@ class SchedulerReportClient(object):
                 context, consumer_uuid, resources):
             error_reason = _("Cannot remove resources %s from the allocation "
                              "due to multiple successive generation conflicts "
-                             "in placement.")
+                             "in placement. To clean up the leaked resource "
+                             "allocation you can use nova-manage placement "
+                             "audit.")
             raise exception.AllocationUpdateFailed(
                 consumer_uuid=consumer_uuid,
                 error=error_reason % resources)
diff --git a/nova/tests/functional/test_servers.py b/nova/tests/functional/test_servers.py
index 2371af771a92..b3b155ff3400 100644
--- a/nova/tests/functional/test_servers.py
+++ b/nova/tests/functional/test_servers.py
@@ -6406,13 +6406,23 @@ class PortResourceRequestBasedSchedulingTest(
         self.assertComputeAllocationMatchesFlavor(
             allocations, self.compute1_rp_uuid, self.flavor)
 
-        sriov_allocations = allocations[
-            self.sriov_dev_rp_per_host[
-                self.compute1_rp_uuid][self.PF2]]['resources']
+        sriov_dev_rp = self.sriov_dev_rp_per_host[
+            self.compute1_rp_uuid][self.PF2]
+        sriov_allocations = allocations[sriov_dev_rp]['resources']
 
         # this is the leaked allocation in placement
         self.assertPortMatchesAllocation(sriov_port, sriov_allocations)
 
+        allocations[sriov_dev_rp].pop('generation')
+        leaked_allocation = {sriov_dev_rp: allocations[sriov_dev_rp]}
+        self.assertIn(
+            f'Failed to update allocations for consumer {server["id"]}. '
+            f'Error: Cannot remove resources {leaked_allocation} from the '
+            f'allocation due to multiple successive generation conflicts in '
+            f'placement. To clean up the leaked resource allocation you can '
+            f'use nova-manage placement audit.',
+            self.stdlog.logger.output)
+
         # We expect that the port binding is not updated with any RP uuid as
         # the attach failed.
         sriov_binding = sriov_port['binding:profile']