Re: [libvirt] New libvirt-tck failure with libvirt 5.2.0
On 4/10/19 3:33 PM, Jim Fehlig wrote:
On 4/10/19 12:25 PM, Daniel Henrique Barboza wrote:
>
>
> On 4/10/19 3:08 PM, Jim Fehlig wrote:
>> I noticed libvirt-tck test domain/207-disk-media-change.t started
>> failing after updating to libvirt 5.2.0. A bisection fingered commit
>> f1d65853
>>
>> commit f1d6585300001c7b23b8796a0faa4411c3531996
>> Author: Daniel Henrique Barboza <danielhb413(a)gmail.com>
>> Date: Fri Mar 15 18:06:45 2019 -0300
>>
>> domain_conf: check device address before attach
>>
>> This commit prevents a media change on CDROM devices.
>
> Thanks for letting us know. I'll run libvirt-tck (any pointers are
> appreciated -
> first time I've heard about this test suite) and see if I can get a
> fix going.
It's easy to reproduce outside of libvirt-tck. Simply start a VM with
a cdrom device and then try to update the <source> element with 'virsh
attach-device ...'. E.g. with the VM running try to "eject" the cdrom
# cat update-empty-cdrom.xml
<disk type='file' device='cdrom'>
<target dev='hdc'/>
</disk>
# virsh attach-device test update-empty-cdrom.xml
error: Failed to attach device from update-empty-cdrom.xml
error: Requested operation is not valid: Domain already contains a
device with the same address
To give a background on this patch, this was intended to avoid a situation
where a hotplug of a device with the same ID would fall back to a cleanup
code that ended up unplugging the previous existing device in the guest.
This was happening when using the QEMU driver.
What I didn't expect is for a CD-ROM media to be changed using a
attach-device command. I think that the CD-ROM type has specific rules
of not
hot-unplugging itself (i.e. the driver) in the situation I described
above. What
I was expecting for CDROM change media was a VIR_DOMAIN_DEVICE_ACTION_UPDATE
action instead, so this usage completely went under the radar for that
patch.
In fact, there are "update-device" and "change-media" commands that,
according to the man page, are meant for the purpose of media change.
However, the same man page doesn't prohibit the use of attach-device
for media change either. I am not sure why have a change-media command
if attach-device is supposed to handle media change as well, but for
now let's fix the usage of attach-device with CDROM.
Thanks,
DHB
Regards,
Jim