linux-kernel - Re: [RFC PATCH] freezer: revert 27920651fe "PM / Freezer: Make fake_signal_wake_up() wake TASK

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Message-ID: <20111102151354.GA28527@redhat.com>
Date:	Wed, 2 Nov 2011 16:13:54 +0100
From:	Oleg Nesterov <oleg@...hat.com>
To:	Jeff Layton <jlayton@...hat.com>
Cc:	Tejun Heo <tj@...nel.org>, "Rafael J. Wysocki" <rjw@...k.pl>,
	Steve French <sfrench@...ba.org>, linux-kernel@...r.kernel.org,
	linux-pm@...r.kernel.org, linux-cifs@...r.kernel.org,
	"J. Bruce Fields" <bfields@...ldses.org>,
	Neil Brown <neilb@...e.de>, trond.myklebust@...app.com,
	linux-nfs@...r.kernel.org
Subject: Re: [RFC PATCH] freezer: revert 27920651fe "PM / Freezer: Make
	fake_signal_wake_up() wake TASK_KILLABLE tasks too"

On 11/02, Jeff Layton wrote:
>
> On Tue, 1 Nov 2011 14:57:10 -0700
> Tejun Heo <tj@...nel.org> wrote:
>
> > For now, let's go with the count/dont_count.  Can you please write up
> > a patch for that?  Jeff, does this seem okay to you?
> >
>
> Let me make sure I understand since I don't have a great grasp of the
> freezer internals...
>
> This will set the PF_FREEZER_SKIP flag on the task, which prevents
> try_to_freeze_tasks from incrementing the "todo" var for this process
> and should let the suspend proceed.
>
> So this really makes try_to_freeze_tasks set PF_FREEZING on the task,
> but not get upset that it doesn't actually call try_to_freeze().

Yes. PF_FREEZER_SKIP means, "please count me as frozen". This task can
do nothing except refrigerator() after wakeup.

> Is that sufficient for a process that's just sleeping here?

I think this should work... but this is the question to you ;)

Oleg.

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