linux-kernel - Re: [PATCH 0/1] poweroff: change orderly_poweroff() to use schedule

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Message-ID: <CAMOw1v5P1=wayBOWmt8MHjH4cnqjkR1WPCWBoKpK1Jj5_3LJdQ@mail.gmail.com>
Date:	Wed, 13 Mar 2013 20:35:38 -0300
From:	Lucas De Marchi <lucas.demarchi@...fusion.mobi>
To:	Oleg Nesterov <oleg@...hat.com>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andi Kleen <andi@...stfloor.org>,
	Lucas De Marchi <lucas.de.marchi@...il.com>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Paul Mackerras <paulus@...ba.org>, david@...son.dropbear.id.au,
	Kees Cook <keescook@...omium.org>,
	Serge Hallyn <serge.hallyn@...onical.com>,
	"Rafael J. Wysocki" <rjw@...k.pl>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Feng Hong <hongfeng@...vell.com>
Subject: Re: [PATCH 0/1] poweroff: change orderly_poweroff() to use schedule_work()

Hi Oleg,

On Wed, Mar 13, 2013 at 2:46 PM, Oleg Nesterov <oleg@...hat.com> wrote:
> On 03/12, Oleg Nesterov wrote:
>>
>> On 03/12, Linus Torvalds wrote:
>> >
>> > So yeah, I guess
>> > everything could just go into a workqueue.
>>
>> OK, I'll try to make the patch tomorrow. Should be trivial but it is
>> not clear how we should pass "bool force" without allocating the
>> work_struct which would be nice to avoid.
>
> Yes, it would be nice to keep it simple and use a single work/arg.
>
> Could you review? The change is trivial but
>
>         - orderly_poweroff() always return 0.
>
>         - the patch assumes that orderly_poweroff(false) after
>           orderly_poweroff(true) acts as "force = true". Only xen
>           uses "false", I hope this is fine.
>
>           In fact I think we can change poweroff_force argument
>           unconditionally, this "if (force)" check is mostly
>           documentation.

I'm not so familiar with this code, but for me it looks reasonable to
let orderly_poweroff(true) win even if there's an
orderly_poweroff(false) later.

>
>           But we can add the locking or even allocate work_struct
>           every time if this is wrong (or just looks wrong).
>
>         - The patch assumes that orderly_poweroff() doesn't need
>           the keventd_up() check, I hope this is correct...
>
>
> Lucas, Andrew, sorry. If this patch will be applied, then
>
>         kernel-sysc-use-the-simpler-call_usermodehelper.patch

No problem for me... your patch already does what this one is doing.

Lucas De Marchi
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