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

[Stefan Hajnoczi]

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.

(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.

Stefan