Re: [PATCH v2] cgroups: make cftype.unregister_event()void-returning

From: KAMEZAWA Hiroyuki
Date: Mon May 10 2010 - 02:12:36 EST


On Sun, 9 May 2010 03:10:22 +0300
"Kirill A. Shutemov" <kirill@xxxxxxxxxxxxx> wrote:

> Since we unable to handle error returned by cftype.unregister_event()
> properly, let's make the callback void-returning.
>
> mem_cgroup_unregister_event() has been rewritten to be "never fail"
> function. On mem_cgroup_usage_register_event() we save old buffer
> for thresholds array and reuse it in mem_cgroup_usage_unregister_event()
> to avoid allocation.
>
> Signed-off-by: Kirill A. Shutemov <kirill@xxxxxxxxxxxxx>

Hmm, just reusing buffer isn't enough ?
as
tmp = memory->thresholds;
reduce entries on tmp
And what happens when

register
register
register
unregister (use preallocated buffer)
unregister ????
unregister

Thanks,
-Kame

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