linux-kernel - Re: [PATCH AUTOSEL 5.4 192/350] iio: dln2-adc: fix iio_triggered_buffer

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Date:   Sun, 15 Dec 2019 15:58:46 +0000
From:   Jonathan Cameron <jic23@...nel.org>
To:     Sasha Levin <sashal@...nel.org>
Cc:     linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        Alexandru Ardelean <alexandru.ardelean@...log.com>,
        Jonathan Cameron <Jonathan.Cameron@...wei.com>,
        linux-iio@...r.kernel.org
Subject: Re: [PATCH AUTOSEL 5.4 192/350] iio: dln2-adc: fix
 iio_triggered_buffer_postenable() position

On Tue, 10 Dec 2019 16:04:57 -0500
Sasha Levin <sashal@...nel.org> wrote:

> From: Alexandru Ardelean <alexandru.ardelean@...log.com>
> 
> [ Upstream commit a7bddfe2dfce1d8859422124abe1964e0ecd386e ]
> 
> The iio_triggered_buffer_postenable() hook should be called first to
> attach the poll function. The iio_triggered_buffer_predisable() hook is
> called last (as is it should).
> 
> This change moves iio_triggered_buffer_postenable() to be called first. It
> adds iio_triggered_buffer_predisable() on the error paths of the postenable
> hook.
> For the predisable hook, some code-paths have been changed to make sure
> that the iio_triggered_buffer_predisable() hook gets called in case there
> is an error before it.

Again, fixing logic to allow a more generic rework rather than actual bug.

I didn't do a very good job of adding notes to all of these to indicate
they weren't stable material. Sorry about that.

Note I am fairly careful about tagging fixes that should go to stable...

Jonathan

> 
> Signed-off-by: Alexandru Ardelean <alexandru.ardelean@...log.com>
> Signed-off-by: Jonathan Cameron <Jonathan.Cameron@...wei.com>
> Signed-off-by: Sasha Levin <sashal@...nel.org>
> ---
>  drivers/iio/adc/dln2-adc.c | 20 ++++++++++++++------
>  1 file changed, 14 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/iio/adc/dln2-adc.c b/drivers/iio/adc/dln2-adc.c
> index 5fa78c273a258..65c7c9329b1c3 100644
> --- a/drivers/iio/adc/dln2-adc.c
> +++ b/drivers/iio/adc/dln2-adc.c
> @@ -524,6 +524,10 @@ static int dln2_adc_triggered_buffer_postenable(struct iio_dev *indio_dev)
>  	u16 conflict;
>  	unsigned int trigger_chan;
>  
> +	ret = iio_triggered_buffer_postenable(indio_dev);
> +	if (ret)
> +		return ret;
> +
>  	mutex_lock(&dln2->mutex);
>  
>  	/* Enable ADC */
> @@ -537,6 +541,7 @@ static int dln2_adc_triggered_buffer_postenable(struct iio_dev *indio_dev)
>  				(int)conflict);
>  			ret = -EBUSY;
>  		}
> +		iio_triggered_buffer_predisable(indio_dev);
>  		return ret;
>  	}
>  
> @@ -550,6 +555,7 @@ static int dln2_adc_triggered_buffer_postenable(struct iio_dev *indio_dev)
>  		mutex_unlock(&dln2->mutex);
>  		if (ret < 0) {
>  			dev_dbg(&dln2->pdev->dev, "Problem in %s\n", __func__);
> +			iio_triggered_buffer_predisable(indio_dev);
>  			return ret;
>  		}
>  	} else {
> @@ -557,12 +563,12 @@ static int dln2_adc_triggered_buffer_postenable(struct iio_dev *indio_dev)
>  		mutex_unlock(&dln2->mutex);
>  	}
>  
> -	return iio_triggered_buffer_postenable(indio_dev);
> +	return 0;
>  }
>  
>  static int dln2_adc_triggered_buffer_predisable(struct iio_dev *indio_dev)
>  {
> -	int ret;
> +	int ret, ret2;
>  	struct dln2_adc *dln2 = iio_priv(indio_dev);
>  
>  	mutex_lock(&dln2->mutex);
> @@ -577,12 +583,14 @@ static int dln2_adc_triggered_buffer_predisable(struct iio_dev *indio_dev)
>  	ret = dln2_adc_set_port_enabled(dln2, false, NULL);
>  
>  	mutex_unlock(&dln2->mutex);
> -	if (ret < 0) {
> +	if (ret < 0)
>  		dev_dbg(&dln2->pdev->dev, "Problem in %s\n", __func__);
> -		return ret;
> -	}
>  
> -	return iio_triggered_buffer_predisable(indio_dev);
> +	ret2 = iio_triggered_buffer_predisable(indio_dev);
> +	if (ret == 0)
> +		ret = ret2;
> +
> +	return ret;
>  }
>  
>  static const struct iio_buffer_setup_ops dln2_adc_buffer_setup_ops = {