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Reviewed:  https://review.opendev.org/c/openstack/nova/+/785682
Committed: https://opendev.org/openstack/nova/commit/0a7d3794c6dc39976b4cbfe12b1688230ac895a8
Submitter: "Zuul (22348)"
Branch:    master

commit 0a7d3794c6dc39976b4cbfe12b1688230ac895a8
Author: Lee Yarwood <lyarwood@xxxxxxxxxx>
Date:   Fri Apr 9 15:37:23 2021 +0100

    libvirt: Ignore device already in the process of unplug errors
    
    At present QEMU will raise an error to libvirt when a device_del request
    is made for a device that has already partially detached through a
    previous request. This is outlined in more detail in the following
    downstream Red Hat QEMU bug report:
    
    Get libvirtError "Device XX is already in the process of unplug" [..]
    https://bugzilla.redhat.com/show_bug.cgi?id=1878659
    
    Within Nova we can actually ignore this error and allow our existing
    retry logic to attempt again after a short wait, hopefully allowing the
    original request to complete removing the device from the domain.
    
    This change does this and should result in one of the following
    device_del requests raising a VIR_ERR_DEVICE_MISSING error from libvirt.
    _try_detach_device should then translate that libvirt error into a
    DeviceNotFound exception which is itself then ignored by all
    detach_device_with_retry callers and taken to mean that the device has
    detached successfully.
    
    Closes-Bug: #1923206
    Change-Id: I0e068043d8267ab91535413d950a3e154c2234f7


** Changed in: nova
       Status: In Progress => Fix Released

** Bug watch added: Red Hat Bugzilla #1878659
   https://bugzilla.redhat.com/show_bug.cgi?id=1878659

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https://bugs.launchpad.net/bugs/1923206

Title:
  libvirt.libvirtError: internal error: unable to execute QEMU command
  'device_del': Device $device is already in the process of unplug

Status in OpenStack Compute (nova):
  Fix Released

Bug description:
  Description
  ===========
  This was initially reported downstream against QEMU in the following bug:

  Get libvirtError "Device XX is already in the process of unplug" when detach device in OSP env
  https://bugzilla.redhat.com/show_bug.cgi?id=1878659

  I first saw the error crop up while testing q35 in TripleO in the
  following job:

  https://c6b36562677324bf8249-804f3f4695b3063292bbb3235f424ae0.ssl.cf1.rackcdn.com/785027/5/check
  /tripleo-ci-
  centos-8-standalone/6860050/logs/undercloud/var/log/containers/nova
  /nova-compute.log

  2021-04-09 11:09:53.702 8 DEBUG nova.virt.libvirt.guest [req-4d0b64d5-a2cf-4a6e-a2f7-f6cc7ced4df1 7e2b737ed8f04b3ca819841a41be66c1 d4d933c7b10c462c8141820b0e70822b - default default] Attempting initial detach for device vdb detach_device_with_retry /usr/lib/python3.6/site-packages/nova/virt/libvirt/guest.py:455
  [..]
  2021-04-09 11:09:58.721 8 DEBUG nova.virt.libvirt.guest [req-4d0b64d5-a2cf-4a6e-a2f7-f6cc7ced4df1 7e2b737ed8f04b3ca819841a41be66c1 d4d933c7b10c462c8141820b0e70822b - default default] Start retrying detach until device vdb is gone. detach_device_with_retry /usr/lib/python3.6/site-packages/nova/virt/libvirt/guest.py:471
  [..]
  2021-04-09 11:09:58.729 8 ERROR oslo.service.loopingcall libvirt.libvirtError: internal error: unable to execute QEMU command 'device_del': Device virtio-disk1 is already in the process of unplug

  
  Steps to reproduce
  ==================
  Unclear at present, it looks like a genuine QEMU bug that causes it to fail when a repeat request to device_del a device comes in instead of ignore the request as would previously happen. I've asked for clarification in the downstream QEMU bug.

  Expected result
  ===============
  Repeat calls to device_del are ignored or the failure while raised is ignored by Nova.

  Actual result
  =============
  Repeat calls to device_del lead to an error being raised to Nova via libvirt that causes the detach to fail while it still succeeds asynchronously within QEMU. 

  Environment
  ===========
  1. Exact version of OpenStack you are running. See the following
    list for all releases: http://docs.openstack.org/releases/

     master

  2. Which hypervisor did you use?
     (For example: Libvirt + KVM, Libvirt + XEN, Hyper-V, PowerKVM, ...)
     What's the version of that?

     libvirt + QEMU/KVM

  2. Which storage type did you use?
     (For example: Ceph, LVM, GPFS, ...)
     What's the version of that?

     N/A

  3. Which networking type did you use?
     (For example: nova-network, Neutron with OpenVSwitch, ...)

     N/A

  Logs & Configs
  ==============
  See above.

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