On 02/03/2012 06:27 PM, Paolo Bonzini wrote:
On 02/03/2012 03:27 PM, Anthony Liguori wrote:
On 02/02/2012 10:45 AM, Paolo Bonzini wrote:
The reference that is returned by qdev_device_add is never given
back, so that device_del does not cause the refcount to go to zero
(and thus does nothing).
Signed-off-by: Paolo Bonzini<pbonz...@redhat.com>
This isn't needed in qom-upstream.14. Here's why:
object_init does not increase the reference count
object_property_add_child increases the reference count
object_new increases the reference count
object_delete decrements the reference count
object_property_del_child decreases the reference count
object_delete calls object_property_del_child(obj->parent, obj)
qdev_device_add calls object_new and object_property_add_child
-> ref == 2
qdev_device_del calls object_delete
-> ref -= 2
In qom-upstream.13, object_delete wasn't calling
object_property_del_child which is why you saw the behavior you did.
This problem would still exist with a composed device so dropping the
reference here isn't enough.
I trust you for now. :)
It really seems like my patch is obviously correct so, if it's not needed
anymore there may be another bug elsewhere that masks it.
There's no object_ref() in qdev_device_add(). The 2 references come from adding
a child link to /peripheral and via object_new().
object_free() drops a reference (it's called in qdev_device_del()) and in the
process of calling object_free(), it also calls object_unparent() which will
drop the reference from the parent.
I'm not thrilled about the way reference counting is done now. Perhaps we
should do a gobject style floating reference...
Regards,
Anthony Liguori
Paolo
