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Date: Mon, 27 Aug 2012 13:46:05 +0200
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Subject: Re: [Qemu-devel] [RFC PATCH 0/9] qom: improve reference counting
 and hotplug
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To: Anthony Liguori <anthony@codemonkey.ws>
Cc: Paolo Bonzini <pbonzini@redhat.com>, Liu Ping Fan <pingfank@linux.vnet.ibm.com>, liu ping fan <qemulist@gmail.com>, qemu-devel@nongnu.org

Am 27.08.2012 09:22, schrieb liu ping fan:
> On Sun, Aug 26, 2012 at 11:51 PM, Anthony Liguori <aliguori@us.ibm.com>=
 wrote:
>> Right now, you need to pair up object_new with object_delete.  This is
>> impractical when using reference counting because we would like to ens=
ure that
>> object_unref() also frees memory when needed.
>>
>> The first few patches fix this problem by introducing a release callba=
ck so
>> that objects that need special release behavior (i.e. g_free) can do t=
hat.
>>
>> Since link and child properties all hold references, in order to actua=
lly free
>> an object, we need to break those links.  User created devices end up =
as
>> children of a container.  But child properties cannot be removed which=
 means
>> there's no obvious way to remove the reference and ultimately free the=
 object.
>>
> Why? Since we call _add_child() in qdev_device_add(), why can not we
> call object_property_del_child() for qmp_device_del(). Could you
> explain it more detail?

Seconded. If we hot-unplug a device, we should surely remove its child<>
property from /machine/unassigned or parent bus or whatever.
Why is it that child<> properties cannot be removed?

Andreas

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