On 08.06.2018 11:03, Igor Mammedov wrote:
> On Fri, 8 Jun 2018 09:40:04 +0200
> David Hildenbrand <da...@redhat.com> wrote:
>
>> On 08.06.2018 09:27, Christian Borntraeger wrote:
>>>
>>>
>>> On 06/08/2018 09:25 AM, Cornelia Huck wrote:
>>>> On Thu, 7 Jun 2018 18:52:18 +0200
>>>> David Hildenbrand <da...@redhat.com> wrote:
>>>>
>>>>> Let's introduce and use local error variables in the hotplug handler
>>>>> functions.
>>>>>
>>>>> Signed-off-by: David Hildenbrand <da...@redhat.com>
>>>>> ---
>>>>> hw/s390x/s390-virtio-ccw.c | 11 ++++++++---
>>>>> 1 file changed, 8 insertions(+), 3 deletions(-)
>>>>>
>>>>> diff --git a/hw/s390x/s390-virtio-ccw.c b/hw/s390x/s390-virtio-ccw.c
>>>>> index 7ae5fb38dd..29ea50a177 100644
>>>>> --- a/hw/s390x/s390-virtio-ccw.c
>>>>> +++ b/hw/s390x/s390-virtio-ccw.c
>>>>> @@ -434,18 +434,23 @@ static void s390_machine_reset(void)
>>>>> static void s390_machine_device_plug(HotplugHandler *hotplug_dev,
>>>>> DeviceState *dev, Error **errp)
>>>>> {
>>>>> + Error *local_err = NULL;
>>>>> +
>>>>> if (object_dynamic_cast(OBJECT(dev), TYPE_CPU)) {
>>>>> - s390_cpu_plug(hotplug_dev, dev, errp);
>>>>> + s390_cpu_plug(hotplug_dev, dev, &local_err);
>>>>> }
>>>>> + error_propagate(errp, local_err);
>>>>> }
>>>>>
>>>>> static void s390_machine_device_unplug_request(HotplugHandler
>>>>> *hotplug_dev,
>>>>> DeviceState *dev, Error
>>>>> **errp)
>>>>> {
>>>>> + Error *local_err = NULL;
>>>>> +
>>>>> if (object_dynamic_cast(OBJECT(dev), TYPE_CPU)) {
>>>>> - error_setg(errp, "CPU hot unplug not supported on this machine");
>>>>> - return;
>>>>> + error_setg(&local_err, "CPU hot unplug not supported on this
>>>>> machine");
>>>>> }
>>>>> + error_propagate(errp, local_err);
>>>>> }
>>>>>
>>>>> static CpuInstanceProperties s390_cpu_index_to_props(MachineState *ms,
>>>>
>>>> Just seeing this patch by itself, it does not really make much sense.
>>>> Even if this is a split out clean-up series, I'd prefer this to go
>>>> together with a patch that actually adds something more to the
>>>> plug/unplug functions.
>>>
>>> +1. It is hard to see the "why". Maybe a better patch description could
>>> help here?
>>>
>>
>> When checking for an error (*errp) we should make sure that we don't
>> dereference the NULL pointer. I will be doing that in the future (memory
>> devices), but as you both don't seem to like this patch, I'll drop it
>> for now.
> hotplug handlers aren't called with NULL errp, so it not really necessary.
> To be on the safe side we can ensure that errp is not NULL doing something
> like:
They are, but not on s390x :) But we should never life with such
assumptions - calling code may change. Passing NULL results right now
not in a crash, but the "return" value in case of a failure cannot be
indicated.
Maybe we should even change all users of NULL for errp to use &error_abort.
For now I dropped these "local_err" patches and kept only the spapr
cleanups.
>
> diff --git a/hw/core/hotplug.c b/hw/core/hotplug.c
> index 17ac986..dc9e4bf 100644
> --- a/hw/core/hotplug.c
> +++ b/hw/core/hotplug.c
> @@ -52,6 +52,7 @@ void hotplug_handler_unplug(HotplugHandler *plug_handler,
> {
> HotplugHandlerClass *hdc = HOTPLUG_HANDLER_GET_CLASS(plug_handler);
>
> + g_assert(errp);
> if (hdc->unplug) {
> hdc->unplug(plug_handler, plugged_dev, errp);
> }
>
> and do it for all similar wrappers in this file
>
>
--
Thanks,
David / dhildenb
