linux-kernel - Re: [PATCH AUTOSEL 4.4 17/35] iio: st_accel: fix iio_triggered_buffer

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Date:   Mon, 22 Jul 2019 06:47:47 +0000
From:   "Ardelean, Alexandru" <alexandru.Ardelean@...log.com>
To:     "sashal@...nel.org" <sashal@...nel.org>,
        "jic23@...nel.org" <jic23@...nel.org>
CC:     "stable@...r.kernel.org" <stable@...r.kernel.org>,
        "Jonathan.Cameron@...wei.com" <Jonathan.Cameron@...wei.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "denis.ciocca@...com" <denis.ciocca@...com>,
        "linux-iio@...r.kernel.org" <linux-iio@...r.kernel.org>
Subject: Re: [PATCH AUTOSEL 4.4 17/35] iio: st_accel: fix
 iio_triggered_buffer_{pre,post}enable positions

On Sun, 2019-07-21 at 18:23 +0100, Jonathan Cameron wrote:
> [External]
> 
> On Fri, 19 Jul 2019 00:14:05 -0400
> Sasha Levin <sashal@...nel.org> wrote:
> 
> > From: Alexandru Ardelean <alexandru.ardelean@...log.com>
> > 
> > [ Upstream commit 05b8bcc96278c9ef927a6f25a98e233e55de42e1 ]
> > 
> > The iio_triggered_buffer_{predisable,postenable} functions attach/detach
> > the poll functions.
> > 
> > For the predisable hook, the disable code should occur before detaching
> > the poll func, and for the postenable hook, the poll func should be
> > attached before the enable code.
> > 
> > Signed-off-by: Alexandru Ardelean <alexandru.ardelean@...log.com>
> > Acked-by: Denis Ciocca <denis.ciocca@...com>
> > Signed-off-by: Jonathan Cameron <Jonathan.Cameron@...wei.com>
> > Signed-off-by: Sasha Levin <sashal@...nel.org>
> Hi Sasha,
> 
> This should do any harm, but I deliberately didn't cc stable on
> this one.
> 
> Alex, my assumption on this one is that it was fixing a logical
> ordering problem, but one that had no visible impact.
> Whilst the pollfunc will be attached too early, the trigger
> will be disabled for the whole of this function anyway so
> it shouldn't cause any visible problem.  Is that a correct interpretation?

Yes.
That is correct.

Maybe I'll change the commit title format so that there is no confusion.
It's a fix, but not in the sense that something was broken.
Just something that is the realm of cleaning up.

Thanks
Alex

> There are going to be a few more similar fixes in the near future
> as Alex is trying to tidy up various paths so we can do a general
> bit of refactoring.
> 
> If I'm too late for this, then not a problem, just noise
> in the stable release.
> 
> Jonathan
> 
> 
> > ---
> >  drivers/iio/accel/st_accel_buffer.c | 22 +++++++++++++---------
> >  1 file changed, 13 insertions(+), 9 deletions(-)
> > 
> > diff --git a/drivers/iio/accel/st_accel_buffer.c b/drivers/iio/accel/st_accel_buffer.c
> > index a1e642ee13d6..4f838277184a 100644
> > --- a/drivers/iio/accel/st_accel_buffer.c
> > +++ b/drivers/iio/accel/st_accel_buffer.c
> > @@ -46,17 +46,19 @@ static int st_accel_buffer_postenable(struct iio_dev *indio_dev)
> >  		goto allocate_memory_error;
> >  	}
> >  
> > -	err = st_sensors_set_axis_enable(indio_dev,
> > -					(u8)indio_dev->active_scan_mask[0]);
> > +	err = iio_triggered_buffer_postenable(indio_dev);
> >  	if (err < 0)
> >  		goto st_accel_buffer_postenable_error;
> >  
> > -	err = iio_triggered_buffer_postenable(indio_dev);
> > +	err = st_sensors_set_axis_enable(indio_dev,
> > +					(u8)indio_dev->active_scan_mask[0]);
> >  	if (err < 0)
> > -		goto st_accel_buffer_postenable_error;
> > +		goto st_sensors_set_axis_enable_error;
> >  
> >  	return err;
> >  
> > +st_sensors_set_axis_enable_error:
> > +	iio_triggered_buffer_predisable(indio_dev);
> >  st_accel_buffer_postenable_error:
> >  	kfree(adata->buffer_data);
> >  allocate_memory_error:
> > @@ -65,20 +67,22 @@ static int st_accel_buffer_postenable(struct iio_dev *indio_dev)
> >  
> >  static int st_accel_buffer_predisable(struct iio_dev *indio_dev)
> >  {
> > -	int err;
> > +	int err, err2;
> >  	struct st_sensor_data *adata = iio_priv(indio_dev);
> >  
> > -	err = iio_triggered_buffer_predisable(indio_dev);
> > -	if (err < 0)
> > -		goto st_accel_buffer_predisable_error;
> > -
> >  	err = st_sensors_set_axis_enable(indio_dev, ST_SENSORS_ENABLE_ALL_AXIS);
> >  	if (err < 0)
> >  		goto st_accel_buffer_predisable_error;
> >  
> >  	err = st_sensors_set_enable(indio_dev, false);
> > +	if (err < 0)
> > +		goto st_accel_buffer_predisable_error;
> >  
> >  st_accel_buffer_predisable_error:
> > +	err2 = iio_triggered_buffer_predisable(indio_dev);
> > +	if (!err)
> > +		err = err2;
> > +
> >  	kfree(adata->buffer_data);
> >  	return err;
> >  }