Re: [Qemu-devel] [libvirt] qapi DEVICE_DELETED event issued *before* instance_finalize?!

[Michal Privoznik]

On 02.09.2016 01:11, Alex Williamson wrote:
> Hey,
> 

> 
> It appears that DEVICE_DELETED only means the VM is done with the
> device but libvirt is interpreting it as QEMU is done with the device.
> Which is correct?  Do we need a new event or do we need to fix the
> ordering of this event?  An ordering fix would be more compatible with
> existing libvirt.  Thanks,

What an interesting race. I think the even should be sent only after
both guest and qemu are done with the device. Having two events looks
like too much granularity to me. I mean, even if libvirt learns that
guest has detached device, it still can't do anything until qemu clears
its internal state.

On the other hand, it is clearly documented that the DEVICE_DELETED
event is sent as soon as guest acknowledges completion of device
removal. So libvirt's buggy if we'd follow documentation strictly. But
then again, I don't see much information value in "guest has detached
device but qemu hasn't yet" event. Libvirt would ignore such event.

Michal