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Bug 1618622

Summary: Detaching ('virsh detach-device-alias') shmem returns failure while actually succeeds in dumpxml of VM
Product: Red Hat Enterprise Linux 7 Reporter: jiyan <jiyan>
Component: libvirtAssignee: Peter Krempa <pkrempa>
Status: CLOSED ERRATA QA Contact: Luyao Huang <lhuang>
Severity: medium Docs Contact:
Priority: medium    
Version: 7.6CC: dyuan, fjin, hhan, jinqi, jiyan, lmen, meili, pkrempa, tburke, xuzhang, yalzhang
Target Milestone: rc   
Target Release: ---   
Hardware: x86_64   
OS: Linux   
Whiteboard:
Fixed In Version: libvirt-4.5.0-7.el7 Doc Type: If docs needed, set a value
Doc Text:
Story Points: ---
Clone Of:
: 1618680 (view as bug list) Environment:
Last Closed: 2018-10-30 09:58:28 UTC Type: Bug
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:
Bug Depends On:    
Bug Blocks: 1618680    

Description jiyan 2018-08-17 05:57:23 UTC 
Description of problem:
Detaching ('virsh detach-device-alias') shmem returns failure while actually succeeds in dumpxml of  VM

Version-Release number of selected component (if applicable):
qemu-kvm-rhev-2.12.0-10.el7.x86_64
kernel-3.10.0-933.el7.x86_64
libvirt-4.5.0-6.el7.x86_64

How reproducible:
100%

Steps to Reproduce:
1. Prepare a shutdown VM without shmem conf and shmem.xml file
# virsh domstate test7.6
shut off

# virsh dumpxml test7.6 --inactive |grep shmem
No output

# cat shmem.xml 
    <shmem name='my_shmem0'>
      <model type='ivshmem-plain'/>
      <size unit='M'>4</size>
      <alias name='ua-8a97238f-0eb4-4e94-87bf-3e878b138749'/>
    </shmem>

2. Start VM and hot-plug shmem.xml to VM
# virsh start test7.6
Domain test7.6 started

# virsh attach-device test7.6 shmem.xml 
Device attached successfully

# virsh dumpxml test7.6 |grep shmem -A6
    <shmem name='my_shmem0'>
      <model type='ivshmem-plain'/>
      <size unit='M'>4</size>
      <alias name='ua-8a97238f-0eb4-4e94-87bf-3e878b138749'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x08' function='0x0'/>
    </shmem>

3. Detach shmem from VM
# virsh detach-device-alias test7.6 ua-8a97238f-0eb4-4e94-87bf-3e878b138749
error: Failed to detach device with alias ua-8a97238f-0eb4-4e94-87bf-3e878b138749
error: internal error: unable to execute QEMU command 'object-del': object 'shmmem-ua-8a97238f-0eb4-4e94-87bf-3e878b138749' is in use, can not be deleted

# virsh dumpxml test7.6 |grep shmem -A6
No output

Actual result:
As step-3 shows

Expected result:
Once the virsh cmd returns failure, shmem xml conf should not disappear in dumpxml of VM

Additional info:
>>>>>>>> In Step-3, the qmp info is as following:
 96.073 > 0x7f721c018720 {"execute":"device_del","arguments":{"id":"ua-8a97238f-0eb4-4e94-87bf-3e878b138749"},"id":"libvirt-24"}
 96.076 < 0x7f721c018720 {"return": {}, "id": "libvirt-24"}
 96.076 > 0x7f721c018720 {"execute":"object-del","arguments":{"id":"shmmem-ua-8a97238f-0eb4-4e94-87bf-3e878b138749"},"id":"libvirt-25"}
 96.079 < 0x7f721c018720 {"id": "libvirt-25", "error": {"class": "GenericError", "desc": "object 'shmmem-ua-8a97238f-0eb4-4e94-87bf-3e878b138749' is in use, can not be deleted"}} (libvirt receives the event from qemu.)
 96.092 ! 0x7f721c018720 {"timestamp": {"seconds": 1534483936, "microseconds": 767944}, "event": "DEVICE_DELETED", "data": {"device": "ua-8a97238f-0eb4-4e94-87bf-3e878b138749", "path": "/machine/peripheral/ua-8a97238f-0eb4-4e94-87bf-3e878b138749"}}
 96.093 > 0x7f721c018720 {"execute":"object-del","arguments":{"id":"shmmem-ua-8a97238f-0eb4-4e94-87bf-3e878b138749"},"id":"libvirt-26"}
 96.096 < 0x7f721c018720 {"return": {}, "id": "libvirt-26"}

>>>>>>>> In Step-3, detaching the shmem device by 'virsh detach-device' can succeed
# virsh detach-device test7.6 shmem.xml 
Device detached successfully

# virsh dumpxml test7.6 |grep "<shmem" -A6
No output
Comment 2 Peter Krempa 2018-08-17 07:19:31 UTC 
Fix:

https://www.redhat.com/archives/libvir-list/2018-August/msg01079.html
Comment 3 Peter Krempa 2018-08-17 10:02:50 UTC 
Fixed upstream:

commit 69c20e1090059d8b359fdd435e8ba50db7269be1
Author: Peter Krempa <pkrempa>
Date:   Fri Aug 17 09:11:34 2018 +0200

    qemu: hotplug: Fix asynchronous unplug of 'shmem'
    
    commit 5c81c342a7 forgot to skip the detaching of the shmem backend
    when async unplug is requested which meant that we've tried to unplug
    the backend prior to delivery of the DEVICE_DELETED event.
Comment 6 Luyao Huang 2018-08-29 09:23:03 UTC 
Verify this bug with libvirt-4.5.0-7.el7.x86_64:

1. prepare a running vm:

# virsh list --all
 Id    Name                           State
----------------------------------------------------
 31    vm1                            running

2. attach shmem device:

# virsh attach-device vm1 shmem.xml
Device attached successfully

3. detach it use detach-device-alias:

# virsh detach-device-alias vm1 ua-123
Device detach request sent successfully

4. recheck xml and cannot find device

# virsh dumpxml vm1 |grep ua-123
Comment 8 errata-xmlrpc 2018-10-30 09:58:28 UTC 
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://access.redhat.com/errata/RHSA-2018:3113