From mboxrd@z Thu Jan  1 00:00:00 1970
From: Oleg Nesterov <oleg@redhat.com>
Subject: Re: [PATCH 1/1] thinkpad-acpi: kill hotkey_thread_mutex
Date: Tue, 26 Mar 2013 14:09:19 +0100
Message-ID: <20130326130918.GA29941@redhat.com>
References: <201303042055.38040.maciej.rutecki@gmail.com> <20130307175305.GA15631@redhat.com> <20130307175359.GB15631@redhat.com> <3714515.nbfe9U9zSg@vostro.rjw.lan>
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To: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Henrique de Moraes Holschuh <hmh@hmh.eng.br>, Mandeep Singh Baines <msb@chromium.org>, Linux Kernel Mailing List <linux-kernel@vger.kernel.org>, linux-acpi@vger.kernel.org, ibm-acpi@hmh.eng.br, ibm-acpi-devel@lists.sourceforge.net, platform-driver-x86@vger.kernel.org, Aaron Lu <aaron.lu@intel.com>, Tejun Heo <tj@kernel.org>, Andrew Morton <akpm@linux-foundation.org>, Artem Savkov <artem.savkov@gmail.com>
List-Id: linux-acpi@vger.kernel.org

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@gmail.com>
> > Reported-by: Maciej Rutecki <maciej.rutecki@gmail.com>
> > Signed-off-by: Oleg Nesterov <oleg@redhat.com>
>
> I wonder if anyone is taking care of this patch?

IIRC, it is already in -mm tree.





> Rafael
> 
> 
> > --- 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
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> > More majordomo info at  http://vger.kernel.org/majordomo-info.html
> -- 
> I speak only for myself.
> Rafael J. Wysocki, Intel Open Source Technology Center.