linux-kernel - Re: [PATCH 1/2] iio: adc: ad7298: convert probe to device-managed functions

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Date:   Sat, 28 Nov 2020 13:04:33 +0000
From:   Jonathan Cameron <jic23@...nel.org>
To:     Alexandru Ardelean <alexandru.ardelean@...log.com>
Cc:     <linux-iio@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <colin.king@...onical.com>
Subject: Re: [PATCH 1/2] iio: adc: ad7298: convert probe to device-managed
 functions

On Fri, 27 Nov 2020 11:40:37 +0200
Alexandru Ardelean <alexandru.ardelean@...log.com> wrote:

> This change converts the probe of this driver to use device-managed
> register functions, and a devm_add_action_or_reset() for the regulator
> disable.
> 
> With this, the exit & error paths can be removed.
> Another side-effect is that this should avoid some static-analyzer's check
> with respect to a potential null dereference of the regulator. The null
> dereference isn't likely to happen (under normal operation), so there isn't
> a requirement to have this fixed/backported in other releases.
> 
> As a note: this is removing spi_set_drvdata() since there is no other
> spi_get_drvdata() (or dev_get_drvdata()) call that need it.
> 
> Cc: Colin Ian King <colin.king@...onical.com>
> Signed-off-by: Alexandru Ardelean <alexandru.ardelean@...log.com>
Series applied to the togreg branch of iio.git and pushed out as testing
for the autobuilders to work their magic.

Thanks,

Jonathan

> ---
>  drivers/iio/adc/ad7298.c | 46 +++++++++++++---------------------------
>  1 file changed, 15 insertions(+), 31 deletions(-)
> 
> diff --git a/drivers/iio/adc/ad7298.c b/drivers/iio/adc/ad7298.c
> index fa1047f74a1f..ecdb01bd5b2f 100644
> --- a/drivers/iio/adc/ad7298.c
> +++ b/drivers/iio/adc/ad7298.c
> @@ -279,6 +279,13 @@ static const struct iio_info ad7298_info = {
>  	.update_scan_mode = ad7298_update_scan_mode,
>  };
>  
> +static void ad7298_reg_disable(void *data)
> +{
> +	struct regulator *reg = data;
> +
> +	regulator_disable(reg);
> +}
> +
>  static int ad7298_probe(struct spi_device *spi)
>  {
>  	struct ad7298_state *st;
> @@ -306,9 +313,12 @@ static int ad7298_probe(struct spi_device *spi)
>  		ret = regulator_enable(st->reg);
>  		if (ret)
>  			return ret;
> -	}
>  
> -	spi_set_drvdata(spi, indio_dev);
> +		ret = devm_add_action_or_reset(&spi->dev, ad7298_reg_disable,
> +					       st->reg);
> +		if (ret)
> +			return ret;
> +	}
>  
>  	st->spi = spi;
>  
> @@ -334,37 +344,12 @@ static int ad7298_probe(struct spi_device *spi)
>  	spi_message_add_tail(&st->scan_single_xfer[1], &st->scan_single_msg);
>  	spi_message_add_tail(&st->scan_single_xfer[2], &st->scan_single_msg);
>  
> -	ret = iio_triggered_buffer_setup(indio_dev, NULL,
> +	ret = devm_iio_triggered_buffer_setup(&spi->dev, indio_dev, NULL,
>  			&ad7298_trigger_handler, NULL);
>  	if (ret)
> -		goto error_disable_reg;
> -
> -	ret = iio_device_register(indio_dev);
> -	if (ret)
> -		goto error_cleanup_ring;
> -
> -	return 0;
> -
> -error_cleanup_ring:
> -	iio_triggered_buffer_cleanup(indio_dev);
> -error_disable_reg:
> -	if (st->ext_ref)
> -		regulator_disable(st->reg);
> -
> -	return ret;
> -}
> -
> -static int ad7298_remove(struct spi_device *spi)
> -{
> -	struct iio_dev *indio_dev = spi_get_drvdata(spi);
> -	struct ad7298_state *st = iio_priv(indio_dev);
> -
> -	iio_device_unregister(indio_dev);
> -	iio_triggered_buffer_cleanup(indio_dev);
> -	if (st->ext_ref)
> -		regulator_disable(st->reg);
> +		return ret;
>  
> -	return 0;
> +	return devm_iio_device_register(&spi->dev, indio_dev);
>  }
>  
>  static const struct spi_device_id ad7298_id[] = {
> @@ -378,7 +363,6 @@ static struct spi_driver ad7298_driver = {
>  		.name	= "ad7298",
>  	},
>  	.probe		= ad7298_probe,
> -	.remove		= ad7298_remove,
>  	.id_table	= ad7298_id,
>  };
>  module_spi_driver(ad7298_driver);