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

[KAMEZAWA Hiroyuki]

On Mon, 10 May 2010 15:08:15 +0900
KAMEZAWA Hiroyuki <kamezawa.hiroyu at jp.fujitsu.com> wrote:

> On Sun,  9 May 2010 03:10:22 +0300
> "Kirill A. Shutemov" <kirill at 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 at 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 at jp.fujitsu.com>

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