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Date: Sat, 3 Mar 2007 02:33:37 +0300
From: Oleg Nesterov <oleg@tv-sign.ru>
To: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>, Anton Blanchard <anton@samba.org>,
       Andrew Morton <akpm@osdl.org>, Pavel Machek <pavel@ucw.cz>,
       LKML <linux-kernel@vger.kernel.org>,
       Aneesh Kumar <aneesh.kumar@gmail.com>,
       Srivatsa Vaddagiri <vatsa@in.ibm.com>,
       Gautham R Shenoy <ego@in.ibm.com>
Subject: Re: [PATCH -mm 3/7] Freezer: Remove PF_NOFREEZE from rcutorture thread
Message-ID: <20070302233337.GA267@tv-sign.ru>
References: <200702260800.49603.rjw@sisk.pl> <200703011609.43804.rjw@sisk.pl> <20070301193826.GA14587@kryten> <200703012054.26940.rjw@sisk.pl> <20070302213549.GC2373@linux.vnet.ibm.com>
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On 03/02, Paul E. McKenney wrote:
>
> One way to embed try_to_freeze() into kthread_should_stop() might be
> as follows:
> 
> 	int kthread_should_stop(void)
> 	{
> 		if (kthread_stop_info.k == current)
> 			return 1;
> 		try_to_freeze();
> 		return 0;
> 	}

I think this is dangerous. For example, worker_thread() will probably
need some special actions after return from refrigerator. Also, a kernel
thread may check kthread_should_stop() in the place where try_to_freeze()
is not safe.

Perhaps we should introduce a new helper which does this.

Oleg.