From: Anthony Liguori <anthony@codemonkey.ws>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: Jan Kiszka <jan.kiszka@siemens.com>,
Liu Ping Fan <pingfank@linux.vnet.ibm.com>,
qemu-devel <qemu-devel@nongnu.org>
Subject: Re: [Qemu-devel] [PATCH] qom: Use atomics for object refcounting
Date: Tue, 02 Jul 2013 11:36:01 -0500 [thread overview]
Message-ID: <8761wsc426.fsf@codemonkey.ws> (raw)
In-Reply-To: <51D2F2D5.90801@redhat.com>
Paolo Bonzini <pbonzini@redhat.com> writes:
> Il 02/07/2013 16:47, Anthony Liguori ha scritto:
>> Jan Kiszka <jan.kiszka@siemens.com> writes:
>>
>>> Objects can soon be referenced/dereference outside the BQL. So we need
>>> to use atomics in object_ref/unref.
>>>
>>> Based on patch by Liu Ping Fan.
>>>
>>> Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
>>> ---
>>> qom/object.c | 5 ++---
>>> 1 files changed, 2 insertions(+), 3 deletions(-)
>>>
>>> diff --git a/qom/object.c b/qom/object.c
>>> index 803b94b..a76a30b 100644
>>> --- a/qom/object.c
>>> +++ b/qom/object.c
>>> @@ -683,16 +683,15 @@ GSList *object_class_get_list(const char *implements_type,
>>>
>>> void object_ref(Object *obj)
>>> {
>>> - obj->ref++;
>>> + __sync_fetch_and_add(&obj->ref, 1);
>>> }
>>>
>>> void object_unref(Object *obj)
>>> {
>>> g_assert(obj->ref > 0);
>>> - obj->ref--;
>>>
>>> /* parent always holds a reference to its children */
>>> - if (obj->ref == 0) {
>>> + if (__sync_sub_and_fetch(&obj->ref, 1) == 0) {
>>> object_finalize(obj);
>>> }
>>> }
>>
>> Should we introduce something akin to kref now that referencing counting
>> has gotten fancy?
>
> I'm not a big fan of kref (it seems _too_ thin a wrapper to me, i.e. it
> doesn't really wrap enough to be useful), but I wouldn't oppose it if
> someone else does it.
I had honestly hoped Object was light enough to be used for this
purpose. What do you think?
Regards,
Anthony Liguori
>
> Paolo
next prev parent reply other threads:[~2013-07-02 16:36 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-07-02 9:36 [Qemu-devel] [PATCH] qom: Use atomics for object refcounting Jan Kiszka
2013-07-02 11:15 ` Andreas Färber
2013-07-02 11:28 ` Paolo Bonzini
2013-07-02 11:44 ` Jan Kiszka
2013-07-02 11:49 ` Paolo Bonzini
2013-07-02 11:52 ` Jan Kiszka
2013-07-02 12:00 ` Paolo Bonzini
2013-07-02 14:47 ` Anthony Liguori
2013-07-02 15:33 ` Paolo Bonzini
2013-07-02 16:36 ` Anthony Liguori [this message]
2013-07-03 1:23 ` liu ping fan
2013-07-03 16:36 ` Andreas Färber
2013-07-04 4:46 ` liu ping fan
2013-07-04 5:43 ` Andreas Färber
2013-07-04 7:21 ` liu ping fan
2013-07-04 7:59 ` Paolo Bonzini
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