FileNotFound when offlining a core due to a privsep context missing

[Sylvain Bauza]

When we created the CPU power interface, we forgot to add a specific privsep decorator for the set_offline() method :
https://review.opendev.org/c/openstack/nova/+/868236/5/nova/virt/libvirt/cpu/core.py#63

As a result, we have a FileNotFound due to a permission error when restarting the nova-compute service :

Jun 05 16:18:49 sbauza-dev2 nova-compute[76374]: ERROR oslo_service.service Traceback (most recent call last):
Jun 05 16:18:49 sbauza-dev2 nova-compute[76374]: ERROR oslo_service.service File "/opt/stack/nova/nova/filesystem.py", line 56, in write_sys
Jun 05 16:18:49 sbauza-dev2 nova-compute[76374]: ERROR oslo_service.service with open(os.path.join(SYS, path), mode='w') as fd:
Jun 05 16:18:49 sbauza-dev2 nova-compute[76374]: ERROR oslo_service.service PermissionError: [Errno 13] Permission denied: '/sys/devices/system/cpu/cpu1/online'
Jun 05 16:18:49 sbauza-dev2 nova-compute[76374]: ERROR oslo_service.service
Jun 05 16:18:49 sbauza-dev2 nova-compute[76374]: ERROR oslo_service.service The above exception was the direct cause of the following exception:
Jun 05 16:18:49 sbauza-dev2 nova-compute[76374]: ERROR oslo_service.service
Jun 05 16:18:49 sbauza-dev2 nova-compute[76374]: ERROR oslo_service.service Traceback (most recent call last):
Jun 05 16:18:49 sbauza-dev2 nova-compute[76374]: ERROR oslo_service.service File "/usr/local/lib/python3.10/dist-packages/oslo_service/service.py", line 806, in run_service
Jun 05 16:18:49 sbauza-dev2 nova-compute[76374]: ERROR oslo_service.service service.start()
Jun 05 16:18:49 sbauza-dev2 nova-compute[76374]: ERROR oslo_service.service File "/opt/stack/nova/nova/service.py", line 162, in start
Jun 05 16:18:49 sbauza-dev2 nova-compute[76374]: ERROR oslo_service.service self.manager.init_host(self.service_ref)
Jun 05 16:18:49 sbauza-dev2 nova-compute[76374]: ERROR oslo_service.service File "/opt/stack/nova/nova/compute/manager.py", line 1608, in init_host
Jun 05 16:18:49 sbauza-dev2 nova-compute[76374]: ERROR oslo_service.service self.driver.init_host(host=self.host)
Jun 05 16:18:49 sbauza-dev2 nova-compute[76374]: ERROR oslo_service.service File "/opt/stack/nova/nova/virt/libvirt/driver.py", line 831, in init_host
Jun 05 16:18:49 sbauza-dev2 nova-compute[76374]: ERROR oslo_service.service libvirt_cpu.power_down_all_dedicated_cpus()
Jun 05 16:18:49 sbauza-dev2 nova-compute[76374]: ERROR oslo_service.service File "/opt/stack/nova/nova/virt/libvirt/cpu/api.py", line 128, in power_down_all_dedicated_cpus
Jun 05 16:18:49 sbauza-dev2 nova-compute[76374]: ERROR oslo_service.service pcpu.online = False
Jun 05 16:18:49 sbauza-dev2 nova-compute[76374]: ERROR oslo_service.service File "/opt/stack/nova/nova/virt/libvirt/cpu/api.py", line 50, in online
Jun 05 16:18:49 sbauza-dev2 nova-compute[76374]: ERROR oslo_service.service core.set_offline(self.ident)
Jun 05 16:18:49 sbauza-dev2 nova-compute[76374]: ERROR oslo_service.service File "/opt/stack/nova/nova/virt/libvirt/cpu/core.py", line 64, in set_offline
Jun 05 16:18:49 sbauza-dev2 nova-compute[76374]: ERROR oslo_service.service filesystem.write_sys(os.path.join(gen_cpu_path(core), 'online'), data='0')
Jun 05 16:18:49 sbauza-dev2 nova-compute[76374]: ERROR oslo_service.service File "/opt/stack/nova/nova/filesystem.py", line 59, in write_sys
Jun 05 16:18:49 sbauza-dev2 nova-compute[76374]: ERROR oslo_service.service raise exception.FileNotFound(file_path=path) from exc
Jun 05 16:18:49 sbauza-dev2 nova-compute[76374]: ERROR oslo_service.service nova.exception.FileNotFound: File /sys/devices/system/cpu/cpu1/online could not be found.
Jun 05 16:18:49 sbauza-dev2 nova-compute[76374]: ERROR oslo_service.service

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.opendev.org/c/openstack/nova/+/885293

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/c/openstack/nova/+/885293
Committed: https://opendev.org/openstack/nova/commit/3fab43786bbdc01087004b973bb0912505150864
Submitter: "Zuul (22348)"
Branch: master

commit 3fab43786bbdc01087004b973bb0912505150864
Author: Sylvain Bauza <email address hidden>
Date: Mon Jun 5 18:22:09 2023 +0200

    cpu: fix the privsep issue when offlining the cpu

    In Icb913ed9be8d508de35e755a9c650ba25e45aca2 we forgot to add a privsep
    decorator for the set_offline() method.

    Change-Id: I769d35907ab9466fe65b942295fd7567a757087a
    Closes-Bug: #2022955

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/nova 28.0.0.0rc1 release candidate.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: stable/2023.1
Review: https://review.opendev.org/c/openstack/nova/+/905675

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/nova 27.3.0 release.