Re: [Qemu-devel] [PATCH] qdev: Fix bus dependency of DeviceState::hotpluggable getter

[Andreas Färber]

Am 09.03.2014 17:40, schrieb Michael S. Tsirkin:
> On Fri, Mar 07, 2014 at 07:13:18PM +0100, Andreas Färber wrote:
>> Commit 1a37eca107cece3ed454bae29eef0bd1fac4a244 (qdev: add
>> "hotpluggable" property to Device) added a property "hotpluggable" to
>> each device, with its getter accessing parent_bus->allow_hotplug.
>>
>> Add a NULL check.
>>
>> Cc: Igor Mammedov <address@hidden>
>> Signed-off-by: Andreas Färber <address@hidden>
> 
> Fair enough but I'm guessing we should
> assume devices without a parent are not
> hotpluggable, should we not?
> 
> Without a bus what handles hotplug?

The device has to, in its realize function.

>> ---
>>  hw/core/qdev.c | 3 ++-
>>  1 file changed, 2 insertions(+), 1 deletion(-)
>>
>> diff --git a/hw/core/qdev.c b/hw/core/qdev.c
>> index 749c83a..cb07863 100644
>> --- a/hw/core/qdev.c
>> +++ b/hw/core/qdev.c
>> @@ -735,7 +735,8 @@ static bool device_get_hotpluggable(Object *obj, Error 
>> **err)
>>      DeviceClass *dc = DEVICE_GET_CLASS(obj);
>>      DeviceState *dev = DEVICE(obj);
>>  
>> -    return dc->hotpluggable && dev->parent_bus->allow_hotplug;
>> +    return dc->hotpluggable && (dev->parent_bus == NULL ||
>> +                                dev->parent_bus->allow_hotplug);
> 
> So maybe this should be:
>>     return dc->hotpluggable && dev->parent_bus &&
>>                                dev->parent_bus->allow_hotplug;
> 
> ?

Hmm... that would render non-x86 CPUs non-hotpluggable. I guess we need
to check dc->bus_type for a NULL value and if non-NULL use your variant
and otherwise mine. I'll give it some more thought.

Thanks,
Andreas

> 
>>  }
>>  
>>  static void device_initfn(Object *obj)
>> -- 
>> 1.8.4.5

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