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Subject: Re: [patch 2.6.15-mm4] sem2mutex: drivers/input/, #2
From: Arjan van de Ven <arjan@infradead.org>
To: Dmitry Torokhov <dtor_core@ameritech.net>
Cc: Faidon Liambotis <faidon@cube.gr>, Ingo Molnar <mingo@elte.hu>,
       linux-kernel@vger.kernel.org
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References: <20060114160253.GA1073@elte.hu> <43C92502.30307@cube.gr>
	 <200601141143.05112.dtor_core@ameritech.net>
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Date: Sat, 14 Jan 2006 17:53:48 +0100
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On Sat, 2006-01-14 at 11:43 -0500, Dmitry Torokhov wrote:
> On Saturday 14 January 2006 11:21, Faidon Liambotis wrote:
> > Ingo Molnar wrote:
> > > @@ -1371,11 +1373,11 @@ static ssize_t psmouse_attr_set_protocol
> > >  			return -EIO;
> > >  		}
> > >  
> > > -		up(&psmouse_sem);
> > > +		mutex_unlock(&psmouse_mutex);
> > >  		serio_unpin_driver(serio);
> > >  		serio_unregister_child_port(serio);
> > >  		serio_pin_driver_uninterruptible(serio);
> > > -		down(&psmouse_sem);
> > > +		mutex_lock(&psmouse_mutex);
> > Isn't that supposed to be the other way around?
> > 
> 
> No, that's correct. We temporarily dropping the lock to let the serio core
> do its job and then reaqcuire it again to finish what we were doing. 

are you REALLY sure? It looks to me as if this function is called from
sysfs.. so you don't know that you have the lock...