Re: [Qemu-devel] [PATCH v8 2/3] qom: pass original path to unparent method

[Paolo Bonzini <pbonzini@redhat.com>]

Il 18/03/2013 15:24, Anthony Liguori ha scritto:
> "Michael S. Tsirkin" <mst@redhat.com> writes:
> 
>> We need to know the original path since unparenting loses this state.
>>
>> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
>> ---
>>  hw/qdev.c            | 4 ++--
>>  include/qom/object.h | 3 ++-
>>  qom/object.c         | 4 +++-
>>  3 files changed, 7 insertions(+), 4 deletions(-)
>>
>> diff --git a/hw/qdev.c b/hw/qdev.c
>> index 741af96..64546cf 100644
>> --- a/hw/qdev.c
>> +++ b/hw/qdev.c
>> @@ -436,7 +436,7 @@ static void qbus_realize(BusState *bus, DeviceState *parent, const char *name)
>>      }
>>  }
>>  
>> -static void bus_unparent(Object *obj)
>> +static void bus_unparent(Object *obj, const char *path)
>>  {
>>      BusState *bus = BUS(obj);
>>      BusChild *kid;
>> @@ -756,7 +756,7 @@ static void device_class_base_init(ObjectClass *class, void *data)
>>      klass->props = NULL;
>>  }
>>  
>> -static void device_unparent(Object *obj)
>> +static void device_unparent(Object *obj, const char *path)
>>  {
>>      DeviceState *dev = DEVICE(obj);
>>      DeviceClass *dc = DEVICE_GET_CLASS(dev);
>> diff --git a/include/qom/object.h b/include/qom/object.h
>> index cf094e7..f0790d4 100644
>> --- a/include/qom/object.h
>> +++ b/include/qom/object.h
>> @@ -330,11 +330,12 @@ typedef struct ObjectProperty
>>  /**
>>   * ObjectUnparent:
>>   * @obj: the object that is being removed from the composition tree
>> + * @path: canonical path that object had if any
>>   *
>>   * Called when an object is being removed from the QOM composition tree.
>>   * The function should remove any backlinks from children objects to @obj.
>>   */
>> -typedef void (ObjectUnparent)(Object *obj);
>> +typedef void (ObjectUnparent)(Object *obj, const char *path);
>>  
>>  /**
>>   * ObjectFree:
>> diff --git a/qom/object.c b/qom/object.c
>> index 3d638ff..21c9da4 100644
>> --- a/qom/object.c
>> +++ b/qom/object.c
>> @@ -362,14 +362,16 @@ static void object_property_del_child(Object *obj, Object *child, Error **errp)
>>  
>>  void object_unparent(Object *obj)
>>  {
>> +    gchar *path = object_get_canonical_path(obj);
>>      object_ref(obj);
>>      if (obj->parent) {
>>          object_property_del_child(obj->parent, obj, NULL);
>>      }
>>      if (obj->class->unparent) {
>> -        (obj->class->unparent)(obj);
>> +        (obj->class->unparent)(obj, path);
>>      }
> 
> I think you should actually just move this call above
> if (obj->parent) { object_parent_del_child(...); }.
> 
> There's no harm AFAICT in doing this and it seems more logical to me to
> have destruction flow start with the subclass and move up to the base
> class.
> 
> This avoids needing a hack like this because the object is still in a
> reasonable state when unparent is called.
> 
> Paolo, do you see anything wrong with this?  I looked at the commit you
> added this in and it doesn't look like it would be a problem.

Yes, seems okay.  Especially if you think of object_property_del_child
as the base class's implementation of unparent.

Paolo