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From: Pavel Machek <pavel@ucw.cz>
To: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>,
	Oleg Nesterov <oleg@tv-sign.ru>,
	Anton Blanchard <anton@samba.org>, Andrew Morton <akpm@osdl.org>,
	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] kthread_should_stop_check_freeze (was: Re: [PATCH -mm 3/7] Freezer: Remove PF_NOFREEZE from rcutorture thread)
Date: Mon, 12 Mar 2007 09:14:59 +0100	[thread overview]
Message-ID: <20070312081459.GI5242@elf.ucw.cz> (raw)
In-Reply-To: <20070312043854.GA4124@linux.vnet.ibm.com>

Hi!

> > > I personally think we should do the opposite, add kthread_should_stop_check_freeze()
> > > or something. kthread_should_stop() is like signal_pending(), we can use
> > > it under spin_lock (and it is probably used this way by some out-of-tree
> > > driver). The new helper is obviously "might_sleep()".
> > 
> > Something like this, perhaps:
> 
> Looks good to me!  The other kthread_should_stop() calls in
> rcutorture.c should also become kthread_should_top_check_freeze().
> 
> Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
> 
> >  include/linux/kthread.h |    1 +
> >  kernel/kthread.c        |   16 ++++++++++++++++
> >  kernel/rcutorture.c     |    5 ++---
> >  3 files changed, 19 insertions(+), 3 deletions(-)
> > 
> > Index: linux-2.6.21-rc3-mm2/kernel/kthread.c
> > ===================================================================
> > --- linux-2.6.21-rc3-mm2.orig/kernel/kthread.c	2007-03-08 21:58:48.000000000 +0100
> > +++ linux-2.6.21-rc3-mm2/kernel/kthread.c	2007-03-11 18:32:59.000000000 +0100
> > @@ -13,6 +13,7 @@
> >  #include <linux/file.h>
> >  #include <linux/module.h>
> >  #include <linux/mutex.h>
> > +#include <linux/freezer.h>
> >  #include <asm/semaphore.h>
> > 
> >  /*
> > @@ -60,6 +61,21 @@ int kthread_should_stop(void)
> >  }
> >  EXPORT_SYMBOL(kthread_should_stop);
> > 
> > +/**
> > + * kthread_should_stop_check_freeze - check if the thread should return now and
> > + * if not, check if there is a freezing request pending for it.
> > + */
> > +int kthread_should_stop_check_freeze(void)
> > +{
> > +	might_sleep();
> > +	if (kthread_stop_info.k == current)
> > +		return 1;
> > +
> > +	try_to_freeze();
> > +	return 0;
> > +}

Can we get better name for this function?

Why is it useful? Caller can do "try_to_freeze()" as well, no?

> >  		}
> >  		rcu_torture_current_version++;
> >  		oldbatch = cur_ops->completed();
> > -		try_to_freeze();
> > -	} while (!kthread_should_stop() && !fullstop);
> > +	} while (!kthread_should_stop_check_freeze() && !fullstop);
> >  	VERBOSE_PRINTK_STRING("rcu_torture_writer task stopping");
> > -	while (!kthread_should_stop())
> > +	while (!kthread_should_stop_check_freeze())
> >  		schedule_timeout_uninterruptible(1);
> >  	return 0;

Aha, I see, here it probably becomes handy.

Actually, no... I do not see it. Why don't you simply move first
try_to_freeze() to beggining of the loop and do

-   while (!kthread_should_stop()) {
             schedule_timeout_uninterruptible(1);
	     try_to_freeze()
}
									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

  reply	other threads:[~2007-03-12  8:16 UTC|newest]

Thread overview: 46+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-02-26  7:00 [PATCH -mm 0/6] Freezer changes Rafael J. Wysocki
2007-02-26  7:02 ` [PATCH -mm 1/6] Freezer: Read PF_BORROWED_MM in a nonracy way Rafael J. Wysocki
2007-02-26  7:05 ` [PATCH -mm 2/6] Freezer: Fix memory ordering in refrigerator Rafael J. Wysocki
2007-02-26 11:32   ` Oleg Nesterov
2007-02-26  7:06 ` [PATCH -mm 3/6] Freezer: Close theoretical race between refrigerator and thaw_tasks Rafael J. Wysocki
2007-02-26  7:08 ` [PATCH -mm 4/6] Freezer: Remove PF_NOFREEZE from rcutorture thread Rafael J. Wysocki
2007-02-26  7:11 ` [PATCH -mm 5/6] Freezer: Remove PF_NOFREEZE from bluetooth threads Rafael J. Wysocki
2007-02-26  7:13 ` [PATCH -mm 6/6] Freezer: Add try_to_freeze calls to all kernel threads Rafael J. Wysocki
2007-03-01 15:05 ` [PATCH -mm 0/7] Freezer changes (take 2) Rafael J. Wysocki
2007-03-01 15:06   ` [PATCH -mm 1/7] Freezer: Read PF_BORROWED_MM in a nonracy way Rafael J. Wysocki
2007-03-01 15:08   ` [PATCH -mm 2/7] Freezer: Close theoretical race between refrigerator and thaw_tasks Rafael J. Wysocki
2007-03-01 16:39     ` Pavel Machek
2007-03-01 15:09   ` [PATCH -mm 3/7] Freezer: Remove PF_NOFREEZE from rcutorture thread Rafael J. Wysocki
2007-03-01 19:38     ` Anton Blanchard
2007-03-01 19:54       ` Rafael J. Wysocki
2007-03-02 21:35         ` Paul E. McKenney
2007-03-02 22:16           ` Anton Blanchard
2007-03-02 23:33           ` Oleg Nesterov
2007-03-03  0:58             ` Paul E. McKenney
2007-03-03 17:32               ` Oleg Nesterov
2007-03-04  4:34                 ` Srivatsa Vaddagiri
2007-03-11 17:49                 ` [PATCH] kthread_should_stop_check_freeze (was: Re: [PATCH -mm 3/7] Freezer: Remove PF_NOFREEZE from rcutorture thread) Rafael J. Wysocki
2007-03-12  4:38                   ` Paul E. McKenney
2007-03-12  8:14                     ` Pavel Machek [this message]
2007-03-12 11:19                       ` Rafael J. Wysocki
2007-03-12 12:23                         ` Oleg Nesterov
2007-03-12 13:24                           ` [PATCH] kthread_should_stop_check_freeze Cedric Le Goater
2007-03-12 18:25                             ` Rafael J. Wysocki
2007-03-12 22:39                         ` [PATCH] kthread_should_stop_check_freeze (was: Re: [PATCH -mm 3/7] Freezer: Remove PF_NOFREEZE from rcutorture thread) Pavel Machek
2007-03-12 22:45                           ` Anton Blanchard
2007-03-13  3:14                             ` Srivatsa Vaddagiri
2007-03-13  9:16                               ` Christoph Hellwig
2007-03-13  9:58                                 ` Srivatsa Vaddagiri
2007-03-13 10:20                                   ` Christoph Hellwig
2007-03-20 18:08                             ` Pavel Machek
2007-03-13  0:58                           ` Paul E. McKenney
2007-03-20 18:10                             ` Pavel Machek
2007-03-13  5:27                   ` Gautham R Shenoy
2007-03-13  5:42                     ` Srivatsa Vaddagiri
2007-03-03  1:03             ` [PATCH -mm 3/7] Freezer: Remove PF_NOFREEZE from rcutorture thread Rafael J. Wysocki
2007-03-02  6:57     ` Gautham R Shenoy
2007-03-02 21:46       ` Paul E. McKenney
2007-03-01 15:10   ` [PATCH -mm 4/7] Freezer: Remove PF_NOFREEZE from bluetooth threads Rafael J. Wysocki
2007-03-01 15:12   ` [PATCH -mm 5/7] Freezer: Add try_to_freeze calls to all kernel threads Rafael J. Wysocki
2007-03-01 15:15   ` [PATCH -mm 6/7] Freezer: Fix vfork problem Rafael J. Wysocki
2007-03-01 15:17   ` [PATCH -mm 7/7] Freezer: Take kernel_execve into consideration Rafael J. Wysocki

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