Re: [PATCH v4 1/1] staging: iio: adc: ad7280a: use devm_* APIs

[Jonathan Cameron <jic23@kernel.org>]

On Mon, 29 Oct 2018 17:52:41 +0100
Slawomir Stepien <sst@poczta.fm> wrote:

> devm_* APIs are device managed and make code simpler.
> 
> Signed-off-by: Slawomir Stepien <sst@poczta.fm>
Very nearly perfect (I think).

But there is one path where we don't quite manage to clean everything up.

> ---
Also, I should be seeing a version log here to avoid me having to look back
at previous versions (potentially) to remind me what needed changing.

Thanks,

Jonathan

>  drivers/staging/iio/adc/ad7280a.c | 95 +++++++++++++------------------
>  1 file changed, 39 insertions(+), 56 deletions(-)
> 
> diff --git a/drivers/staging/iio/adc/ad7280a.c b/drivers/staging/iio/adc/ad7280a.c
> index b736275c10f5..1263b70693ed 100644
> --- a/drivers/staging/iio/adc/ad7280a.c
> +++ b/drivers/staging/iio/adc/ad7280a.c
> @@ -342,6 +342,14 @@ static int ad7280_read_all_channels(struct ad7280_state *st, unsigned int cnt,
>  	return sum;
>  }
>  
> +static void ad7280_sw_power_down(void *data)
> +{
> +	struct ad7280_state *st = data;
> +
> +	ad7280_write(st, AD7280A_DEVADDR_MASTER, AD7280A_CONTROL_HB, 1,
> +		     AD7280A_CTRL_HB_PWRDN_SW | st->ctrl_hb);
> +}
> +
>  static int ad7280_chain_setup(struct ad7280_state *st)
>  {
>  	unsigned int val, n;
> @@ -492,8 +500,8 @@ static int ad7280_channel_init(struct ad7280_state *st)
>  {
>  	int dev, ch, cnt;
>  
> -	st->channels = kcalloc((st->slave_num + 1) * 12 + 2,
> -			       sizeof(*st->channels), GFP_KERNEL);
> +	st->channels = devm_kcalloc(&st->spi->dev, (st->slave_num + 1) * 12 + 2,
> +				    sizeof(*st->channels), GFP_KERNEL);
>  	if (!st->channels)
>  		return -ENOMEM;
>  
> @@ -552,16 +560,18 @@ static int ad7280_channel_init(struct ad7280_state *st)
>  static int ad7280_attr_init(struct ad7280_state *st)
>  {
>  	int dev, ch, cnt;
> +	unsigned int index;
>  
> -	st->iio_attr = kcalloc(2, sizeof(*st->iio_attr) *
> -			       (st->slave_num + 1) * AD7280A_CELLS_PER_DEV,
> -			       GFP_KERNEL);
> +	st->iio_attr = devm_kcalloc(&st->spi->dev, 2, sizeof(*st->iio_attr) *
> +				    (st->slave_num + 1) * AD7280A_CELLS_PER_DEV,
> +				    GFP_KERNEL);
>  	if (!st->iio_attr)
>  		return -ENOMEM;
>  
>  	for (dev = 0, cnt = 0; dev <= st->slave_num; dev++)
>  		for (ch = AD7280A_CELL_VOLTAGE_1; ch <= AD7280A_CELL_VOLTAGE_6;
>  			ch++, cnt++) {
> +			index = dev * AD7280A_CELLS_PER_DEV + ch;
>  			st->iio_attr[cnt].address =
>  				ad7280a_devaddr(dev) << 8 | ch;
>  			st->iio_attr[cnt].dev_attr.attr.mode =
> @@ -571,10 +581,9 @@ static int ad7280_attr_init(struct ad7280_state *st)
>  			st->iio_attr[cnt].dev_attr.store =
>  				ad7280_store_balance_sw;
>  			st->iio_attr[cnt].dev_attr.attr.name =
> -				kasprintf(GFP_KERNEL,
> -					  "in%d-in%d_balance_switch_en",
> -					  dev * AD7280A_CELLS_PER_DEV + ch,
> -					  dev * AD7280A_CELLS_PER_DEV + ch + 1);
> +				devm_kasprintf(&st->spi->dev, GFP_KERNEL,
> +					       "in%d-in%d_balance_switch_en",
> +					       index, index + 1);
>  			ad7280_attributes[cnt] =
>  				&st->iio_attr[cnt].dev_attr.attr;
>  			cnt++;
> @@ -588,10 +597,9 @@ static int ad7280_attr_init(struct ad7280_state *st)
>  			st->iio_attr[cnt].dev_attr.store =
>  				ad7280_store_balance_timer;
>  			st->iio_attr[cnt].dev_attr.attr.name =
> -				kasprintf(GFP_KERNEL,
> -					  "in%d-in%d_balance_timer",
> -					  dev * AD7280A_CELLS_PER_DEV + ch,
> -					  dev * AD7280A_CELLS_PER_DEV + ch + 1);
> +				devm_kasprintf(&st->spi->dev, GFP_KERNEL,
> +					       "in%d-in%d_balance_timer",
> +					       index, index + 1);
>  			ad7280_attributes[cnt] =
>  				&st->iio_attr[cnt].dev_attr.attr;
>  		}
> @@ -909,65 +917,41 @@ static int ad7280_probe(struct spi_device *spi)
>  
>  	ret = ad7280_attr_init(st);
>  	if (ret < 0)
> -		goto error_free_channels;
> +		return ret;
>  
> -	ret = iio_device_register(indio_dev);
> +	ret = devm_add_action(&spi->dev, ad7280_sw_power_down, st);
>  	if (ret)
What state are we left in if the devm_add_action fails?

Answer: Everything is unwound except the thing we were adding the action
for.  So you need to call ad7280_sw_power_down in the error path here.

> -		goto error_free_attr;
> +		return ret;
> +
> +	ret = devm_iio_device_register(&spi->dev, indio_dev);
> +	if (ret)
> +		return ret;
>  
>  	if (spi->irq > 0) {
>  		ret = ad7280_write(st, AD7280A_DEVADDR_MASTER,
>  				   AD7280A_ALERT, 1,
>  				   AD7280A_ALERT_RELAY_SIG_CHAIN_DOWN);
>  		if (ret)
> -			goto error_unregister;
> +			return ret;
>  
>  		ret = ad7280_write(st, ad7280a_devaddr(st->slave_num),
>  				   AD7280A_ALERT, 0,
>  				   AD7280A_ALERT_GEN_STATIC_HIGH |
>  				   (pdata->chain_last_alert_ignore & 0xF));
>  		if (ret)
> -			goto error_unregister;
> -
> -		ret = request_threaded_irq(spi->irq,
> -					   NULL,
> -					   ad7280_event_handler,
> -					   IRQF_TRIGGER_FALLING |
> -					   IRQF_ONESHOT,
> -					   indio_dev->name,
> -					   indio_dev);
> +			return ret;
> +
> +		ret = devm_request_threaded_irq(&spi->dev, spi->irq,
> +						NULL,
> +						ad7280_event_handler,
> +						IRQF_TRIGGER_FALLING |
> +						IRQF_ONESHOT,
> +						indio_dev->name,
> +						indio_dev);
>  		if (ret)
> -			goto error_unregister;
> +			return ret;
>  	}
>  
> -	return 0;
> -error_unregister:
> -	iio_device_unregister(indio_dev);
> -
> -error_free_attr:
> -	kfree(st->iio_attr);
> -
> -error_free_channels:
> -	kfree(st->channels);
> -
> -	return ret;
> -}
> -
> -static int ad7280_remove(struct spi_device *spi)
> -{
> -	struct iio_dev *indio_dev = spi_get_drvdata(spi);
> -	struct ad7280_state *st = iio_priv(indio_dev);
> -
> -	if (spi->irq > 0)
> -		free_irq(spi->irq, indio_dev);
> -	iio_device_unregister(indio_dev);
> -
> -	ad7280_write(st, AD7280A_DEVADDR_MASTER, AD7280A_CONTROL_HB, 1,
> -		     AD7280A_CTRL_HB_PWRDN_SW | st->ctrl_hb);
> -
> -	kfree(st->channels);
> -	kfree(st->iio_attr);
> -
>  	return 0;
>  }
>  
> @@ -982,7 +966,6 @@ static struct spi_driver ad7280_driver = {
>  		.name	= "ad7280",
>  	},
>  	.probe		= ad7280_probe,
> -	.remove		= ad7280_remove,
>  	.id_table	= ad7280_id,
>  };
>  module_spi_driver(ad7280_driver);