Re: [Qemu-ppc] [PATCH v1 8/8] s390x: local error handling in hotplug handler functions

[David Hildenbrand]

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 <address@hidden> wrote:
>>
>>> Let's introduce and use local error variables in the hotplug handler
>>> functions.
>>>
>>> Signed-off-by: David Hildenbrand <address@hidden>
>>> ---
>>>  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.

-- 

Thanks,

David / dhildenb