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Date: Wed, 11 Jun 2014 13:28:11 +0200
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Subject: Re: [Qemu-devel] [PATCH qom v1 1/1] qom: object: remove parent
 pointer when unparenting
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To: Peter Crosthwaite <peter.crosthwaite@xilinx.com>
Cc: Kevin Wolf <kwolf@redhat.com>, Paolo Bonzini <pbonzini@redhat.com>, "qemu-devel@nongnu.org Developers" <qemu-devel@nongnu.org>, Stefan Hajnoczi <stefanha@redhat.com>

Am 11.06.2014 12:19, schrieb Peter Crosthwaite:
> On Wed, Jun 11, 2014 at 6:13 PM, Andreas F=C3=A4rber <afaerber@suse.de>=
 wrote:
>> Am 27.05.2014 02:39, schrieb Peter Crosthwaite:
>>> Certain parts of the QOM framework test this pointer to determine if
>>> an object is parented. Nuke it when the object is unparented to allow
>>> for reuse of an object after unparenting.
>>>
>>> Signed-off-by: Peter Crosthwaite <peter.crosthwaite@xilinx.com>
>>> ---
>>>
>>>  qom/object.c | 1 +
>>>  1 file changed, 1 insertion(+)
>>>
>>> diff --git a/qom/object.c b/qom/object.c
>>> index e42b254..8319e89 100644
>>> --- a/qom/object.c
>>> +++ b/qom/object.c
>>> @@ -402,6 +402,7 @@ void object_unparent(Object *obj)
>>>      if (obj->parent) {
>>>          object_property_del_child(obj->parent, obj, NULL);
>>>      }
>>> +    obj->parent =3D NULL;
>>>      object_unref(obj);
>>>  }
>>>
>>
>> This looks okay to me, and it might also help the segfault on hot-unpl=
ug
>> Stefan and Kevin reported before I went on travels.
>>
>=20
> Welcome back.
>=20
>> Any objection to moving this one line up into the if?
>>
>=20
> No problem. Will respin.

I've done so myself, but now I wonder why we are checking obj->parent at
all there after we already return if !obj->parent? Is this to guard
against ObjectClass::unparent() changing Object::parent? Either way, the
two variants you posted and I suggested should be fine.

Regards,
Andreas

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