Re: [PATCH] pwm: Avoid deadlock warning when removing PWM device

["Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>]

On Tue, Mar 12, 2019 at 10:49:59AM +0100, Geert Uytterhoeven wrote:
> Hi Uwe,
> 
> On Tue, Mar 12, 2019 at 10:23 AM Uwe Kleine-König
> <u.kleine-koenig@pengutronix.de> wrote:
> > On Tue, Mar 12, 2019 at 12:16:34PM +0900, Yoshihiro Shimoda wrote:
> > > diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c
> > > index 1581f6a..2fdd6611 100644
> > > --- a/drivers/pwm/core.c
> > > +++ b/drivers/pwm/core.c
> 
> > > @@ -368,10 +370,12 @@ int pwmchip_remove(struct pwm_chip *chip)
> > >
> > >       free_pwms(chip);
> > >
> > > -     pwmchip_sysfs_unexport(chip);
> > > -
> > >  out:
> > >       mutex_unlock(&pwm_lock);
> > > +
> > > +     if (!ret)
> > > +             pwmchip_sysfs_unexport(chip);
> > > +
> >
> > I wonder if this needs to be done before free_pwms is called. Otherwise
> > the pwmchip is already gone and then something is requested via sysfs.
> 
> The chip itself is not freed, only the pwms array inside, which is not needed
> for matching in pwmchip_sysfs_unexport(), right?

OK, then make this:

I wonder if pwmchip_sysfs_unexport needs to be done before free_pwms is
called. Otherwise the PWMs's representation is already gone and then
something might be requested via sysfs.
 
Best regards
Uwe

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Pengutronix e.K.                           | Uwe Kleine-König            |
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