linux-kernel - Re: [PATCH 1/1] thinkpad-acpi: kill hotkey_thread

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Message-ID: <7586645.G956EhhFvW@vostro.rjw.lan>
Date:	Tue, 26 Mar 2013 14:50:46 +0100
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Oleg Nesterov <oleg@...hat.com>
Cc:	Henrique de Moraes Holschuh <hmh@....eng.br>,
	Mandeep Singh Baines <msb@...omium.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	linux-acpi@...r.kernel.org, ibm-acpi@....eng.br,
	ibm-acpi-devel@...ts.sourceforge.net,
	platform-driver-x86@...r.kernel.org, Aaron Lu <aaron.lu@...el.com>,
	Tejun Heo <tj@...nel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Artem Savkov <artem.savkov@...il.com>
Subject: Re: [PATCH 1/1] thinkpad-acpi: kill hotkey_thread_mutex

On Tuesday, March 26, 2013 02:09:19 PM Oleg Nesterov wrote:
> On 03/26, Rafael J. Wysocki wrote:
> >
> > On Thursday, March 07, 2013 06:53:59 PM Oleg Nesterov wrote:
> > > hotkey_kthread() does try_to_freeze() under hotkey_thread_mutex.
> > >
> > > We can simply kill this mutex, hotkey_poll_stop_sync() does not need
> > > to serialize with hotkey_kthread(). When kthread_stop() returns the
> > > thread is already dead, it called do_exit()->complete_vfork_done().
> > >
> > > Reported-by: Artem Savkov <artem.savkov@...il.com>
> > > Reported-by: Maciej Rutecki <maciej.rutecki@...il.com>
> > > Signed-off-by: Oleg Nesterov <oleg@...hat.com>
> >
> > I wonder if anyone is taking care of this patch?
> 
> IIRC, it is already in -mm tree.

OK, thanks for letting me know.


> > > --- x/drivers/platform/x86/thinkpad_acpi.c
> > > +++ x/drivers/platform/x86/thinkpad_acpi.c
> > > @@ -1965,9 +1965,6 @@ struct tp_nvram_state {
> > >  /* kthread for the hotkey poller */
> > >  static struct task_struct *tpacpi_hotkey_task;
> > >  
> > > -/* Acquired while the poller kthread is running, use to sync start/stop */
> > > -static struct mutex hotkey_thread_mutex;
> > > -
> > >  /*
> > >   * Acquire mutex to write poller control variables as an
> > >   * atomic block.
> > > @@ -2463,8 +2460,6 @@ static int hotkey_kthread(void *data)
> > >  	unsigned int poll_freq;
> > >  	bool was_frozen;
> > >  
> > > -	mutex_lock(&hotkey_thread_mutex);
> > > -
> > >  	if (tpacpi_lifecycle == TPACPI_LIFE_EXITING)
> > >  		goto exit;
> > >  
> > > @@ -2524,7 +2519,6 @@ static int hotkey_kthread(void *data)
> > >  	}
> > >  
> > >  exit:
> > > -	mutex_unlock(&hotkey_thread_mutex);
> > >  	return 0;
> > >  }
> > >  
> > > @@ -2534,9 +2528,6 @@ static void hotkey_poll_stop_sync(void)
> > >  	if (tpacpi_hotkey_task) {
> > >  		kthread_stop(tpacpi_hotkey_task);
> > >  		tpacpi_hotkey_task = NULL;
> > > -		mutex_lock(&hotkey_thread_mutex);
> > > -		/* at this point, the thread did exit */
> > > -		mutex_unlock(&hotkey_thread_mutex);
> > >  	}
> > >  }
> > >  
> > > @@ -3235,7 +3226,6 @@ static int __init hotkey_init(struct ibm
> > >  	mutex_init(&hotkey_mutex);
> > >  
> > >  #ifdef CONFIG_THINKPAD_ACPI_HOTKEY_POLL
> > > -	mutex_init(&hotkey_thread_mutex);
> > >  	mutex_init(&hotkey_thread_data_mutex);
> > >  #endif
> > >  
> > > 
> > > --
> > > To unsubscribe from this list: send the line "unsubscribe linux-acpi" in
> > > the body of a message to majordomo@...r.kernel.org
> > > More majordomo info at  http://vger.kernel.org/majordomo-info.html
> 
-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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