Re: [Qemu-devel] [PATCH 2/2] qapi: convert device_del

[Luiz Capitulino <lcapitulino@redhat.com>]

On Thu, 29 Mar 2012 08:08:51 +0100
Stefan Hajnoczi <stefanha@gmail.com> wrote:

> On Wed, Mar 28, 2012 at 05:50:54PM -0300, Luiz Capitulino wrote:
> >      ret = qdev_unplug(dev, &local_err);
> >      if (error_is_set(&local_err)) {
> > -        qerror_report_err(local_err);
> > -        error_free(local_err);
> > +        error_propagate(errp, local_err);
> > +    } else if (ret) {
> > +        error_set(errp, QERR_UNDEFINED_ERROR);
> 
> Can we make qdev_unplug() void?  I can find no case in QEMU where we
> return != 0 without setting error.  If we fix the function prototype
> this invalid state can be eliminated forever.

Good point, I'll change it.

> 
> (Other functions that take Error **errp are usually void.)
> 
> > diff --git a/qapi-schema.json b/qapi-schema.json
> > index 0d11d6e..ace55f3 100644
> > --- a/qapi-schema.json
> > +++ b/qapi-schema.json
> > @@ -1701,3 +1701,23 @@
> >  # Since: 1.1
> >  ##
> >  { 'command': 'xen-save-devices-state', 'data': {'filename': 'str'} }
> > +
> > +##
> > +# @device_del:
> > +#
> > +# Remove a device from a guest
> > +#
> > +# @id: the name of the device
> > +#
> > +# Returns: Nothing on success
> > +#          If @id is not a valid device, DeviceNotFound
> > +#          If the device does not support unplug, BusNoHotplug
> > +#
> > +# Notes: When this command completes, the device may not be removed from the
> > +#        guest.  Hot removal is an operation that requires guest cooperation.
> > +#        This command merely requests that the guest begin the hot removal
> > +#        process.
> 
> I have not peeked at the implementation in QEMU or libvirt, but is there
> a QMP event for actual removal or would the user need to poll?  This bit
> of information would be useful in the documentation.

There's no event, I'll document it. Is there any preferred method for
polling? query-pci?