linux-kernel - Re: [RFC PATCH] freezer: allow killing of frozen tasks

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Date:	Tue, 20 Aug 2013 14:23:32 +0200
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>
Cc:	Pavel Machek <pavel@....cz>, linux-pm@...r.kernel.org,
	Kyungmin Park <kyungmin.park@...sung.com>,
	Tejun Heo <tj@...nel.org>, LKML <linux-kernel@...r.kernel.org>,
	Colin Cross <ccross@...roid.com>
Subject: Re: [RFC PATCH] freezer: allow killing of frozen tasks

On Tuesday, August 20, 2013 01:20:03 PM Bartlomiej Zolnierkiewicz wrote:
> Change __refrigerator() to allow SIGKILL signal handling during
> the frozen state (by setting task to a TASK_KILLABLE state instead
> of TASK_UNINTERRUPTIBLE one before entering sleep) and make tasks
> leave __refrigerator() upon receiving such signal.
> 
> These changes allow frozen tasks to be killed immediately without
> the need to thaw them first.
> 
> Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>
> Signed-off-by: Kyungmin Park <kyungmin.park@...sung.com>

Well, it doesn't sound like an entirely bad idea to me, but I'd like to know
what Colin and Tejun (CCed now) think about it.

Thanks,
Rafael


> ---
>  kernel/freezer.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/kernel/freezer.c b/kernel/freezer.c
> index b462fa1..0c05a7a 100644
> --- a/kernel/freezer.c
> +++ b/kernel/freezer.c
> @@ -57,12 +57,13 @@ bool __refrigerator(bool check_kthr_stop)
>  	pr_debug("%s entered refrigerator\n", current->comm);
>  
>  	for (;;) {
> -		set_current_state(TASK_UNINTERRUPTIBLE);
> +		set_current_state(TASK_KILLABLE);
>  
>  		spin_lock_irq(&freezer_lock);
>  		current->flags |= PF_FROZEN;
>  		if (!freezing(current) ||
> -		    (check_kthr_stop && kthread_should_stop()))
> +		    (check_kthr_stop && kthread_should_stop()) ||
> +		    fatal_signal_pending(current))
>  			current->flags &= ~PF_FROZEN;
>  		spin_unlock_irq(&freezer_lock);
>  
> 
-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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