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

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Message-ID: <20130313174641.GA28083@redhat.com>
Date:	Wed, 13 Mar 2013 18:46:41 +0100
From:	Oleg Nesterov <oleg@...hat.com>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	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>,
	Lucas De Marchi <lucas.demarchi@...fusion.mobi>
Subject: [PATCH 0/1] poweroff: change orderly_poweroff() to use
	schedule_work()

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.

	  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

should be dropped. Or I can redo this fix on top of -mm cleanup.

> And. It seems there is another problem. argv_split(poweroff_cmd) can
> obviously race with proc_dostring() ?

I'll send another patch...

Oleg.

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