[libvirt] Qemu capability probes lifecycle should be tied to libvirtd

[Christian Ehrhardt]

Hi,
on libvirt 3.10 I see a set of qemu processes used for capability
probing [1] (in my case 8x x86_64 and 3xi386 which seems a lot, but
ok).
But when stopping the service those still stay around [2].

That is correct for guests that were started by libvirt as their
lifecycle isn't tied to the libvirtd service. But those probes are
IMHO tied to the service.

At first this might seem non-relevant, but e.g. when users want to
uninstall they might think on stopping their guests, but I'd assume no
one will clean up the capability probes before the hard removal.
But then on the removal scripts will run into issues e.g. failing to
remove users as they are still in use by those qemu processes.

Right now Distro's have to be aware to clean those up at least at
times where packaging would expect them to be gone, but I wanted to
ask if there would be a consensus that it would be "correct" to stop
the processes on a libvirtd stop?

[1]: http://paste.ubuntu.com/26208661/
[2]: http://paste.ubuntu.com/26208664/

P.S. I discussed this on IRC last Friday, but other than Michael
confirming the current state there was no further traction on the
discussion yet.

-- 
Christian Ehrhardt
Software Engineer, Ubuntu Server
Canonical Ltd