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From: KAMEZAWA Hiroyuki on 10 May 2010 02:20
On Sun, 9 May 2010 03:10:22 +0300
"Kirill A. Shutemov" <kirill(a)shutemov.name> 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(a)shutemov.name>

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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From: KAMEZAWA Hiroyuki on 10 May 2010 02:40
On Mon, 10 May 2010 15:08:15 +0900
KAMEZAWA Hiroyuki <kamezawa.hiroyu(a)jp.fujitsu.com> wrote:

> On Sun, 9 May 2010 03:10:22 +0300
> "Kirill A. Shutemov" <kirill(a)shutemov.name> 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(a)shutemov.name>
>
> 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
>
Ah, sorry my eyes were wrong.

The fix seems to work.

Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu(a)jp.fujitsu.com>

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