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From: Denis CIOCCA <denis.ciocca@st.com>
To: Jonathan Cameron <jic23@jic23.retrosnub.co.uk>,
	Alexandru Ardelean <alexandru.ardelean@analog.com>
Cc: "linux-iio@vger.kernel.org" <linux-iio@vger.kernel.org>,
	Lorenzo Bianconi <lorenzo.bianconi83@gmail.com>
Subject: RE: [PATCH][V2] iio: st_accel: fix iio_triggered_buffer_{pre,post}enable positions
Date: Mon, 10 Jun 2019 21:20:20 +0000
Message-ID: <8501c7c92ca04a46a327681ad1384cc0@SFHDAG2NODE1.st.com> (raw)
In-Reply-To: <20190608150944.5764158f@archlinux>

Hi Jonathan, Alexandru,

I agree with you about the predisable but I am not convinced regarding the postenable.
Few modifications have been made on magn driver and never replicated on accel. I think should be done in the same way magn is implemented.
During postenable kmalloc should be called first because iio_triggered_buffer_postenable function it enables irq and if an interrupt arrives before the memory is allocated (wrong interrupt or failure of switching sensor off from previous disable) it could generate a null pointer exception. Make sense to you?

Thanks & Br,
Denis



-----Original Message-----
From: Jonathan Cameron <jic23@jic23.retrosnub.co.uk> 
Sent: Saturday, June 8, 2019 7:10 AM
To: Alexandru Ardelean <alexandru.ardelean@analog.com>
Cc: linux-iio@vger.kernel.org; Denis CIOCCA <denis.ciocca@st.com>; Lorenzo Bianconi <lorenzo.bianconi83@gmail.com>
Subject: Re: [PATCH][V2] iio: st_accel: fix iio_triggered_buffer_{pre,post}enable positions

On Wed, 29 May 2019 16:58:48 +0300
Alexandru Ardelean <alexandru.ardelean@analog.com> wrote:

> 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@analog.com>
I think this is fine, but I'd like an ack from Lorenzo / Denis.

Note to those who have missed the background on this, the aim is to both tidy up drivers, but long term to allow for simpler reworking of the core by ensuring consistency of ordering and what is done in each of these hooks.

Thanks,

Jonathan

> ---
> Changelog v1 -> v2:
> * record the first error in st_accel_buffer_predisable() and return 
> that
> 
>  drivers/iio/accel/st_accel_buffer.c | 21 ++++++++++++---------
>  1 file changed, 12 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/iio/accel/st_accel_buffer.c 
> b/drivers/iio/accel/st_accel_buffer.c
> index 7fddc137e91e..711ecd9bc898 100644
> --- a/drivers/iio/accel/st_accel_buffer.c
> +++ b/drivers/iio/accel/st_accel_buffer.c
> @@ -40,6 +40,10 @@ static int st_accel_buffer_postenable(struct iio_dev *indio_dev)
>  	int err;
>  	struct st_sensor_data *adata = iio_priv(indio_dev);
>  
> +	err = iio_triggered_buffer_postenable(indio_dev);
> +	if (err < 0)
> +		return err;
> +
>  	adata->buffer_data = kmalloc(indio_dev->scan_bytes, GFP_KERNEL);
>  	if (adata->buffer_data == NULL) {
>  		err = -ENOMEM;
> @@ -51,34 +55,33 @@ static int st_accel_buffer_postenable(struct iio_dev *indio_dev)
>  	if (err < 0)
>  		goto st_accel_buffer_postenable_error;
>  
> -	err = iio_triggered_buffer_postenable(indio_dev);
> -	if (err < 0)
> -		goto st_accel_buffer_postenable_error;
> -
>  	return err;
>  
>  st_accel_buffer_postenable_error:
>  	kfree(adata->buffer_data);
>  allocate_memory_error:
> +	iio_triggered_buffer_predisable(indio_dev);
>  	return err;
>  }
>  
>  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;
>  }


  reply index

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-29 13:01 [PATCH] " Alexandru Ardelean
2019-05-29 13:58 ` [PATCH][V2] " Alexandru Ardelean
2019-06-08 14:09   ` Jonathan Cameron
2019-06-10 21:20     ` Denis CIOCCA [this message]
2019-06-14 10:36       ` Ardelean, Alexandru
2019-06-14 10:47   ` [PATCH][V3] " Alexandru Ardelean
2019-06-17 22:12     ` Denis CIOCCA
2019-06-22  8:28       ` Jonathan Cameron

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