Re: [PATCH v7 5/7] iio: dac: ad5686: read_raw/write_raw: use guard(mutex)()

[David Lechner <dlechner@baylibre.com>]

On 7/10/26 6:20 AM, Rodrigo Alencar via B4 Relay wrote:
> From: Rodrigo Alencar <rodrigo.alencar@analog.com>
> 
> Use guarded mutex lock to facilitate code review when adding new
> attributes. This will allow for early returns, avoiding error-prone
> locking and unlocking in error paths. This also adds missing include
> linux/cleanup.h. Gain-control support will allow the scale attribute
> to be configurable.
> 
> Reviewed-by: Maxwell Doose <m32285159@gmail.com>
> Reviewed-by: Joshua Crofts <joshua.crofts1@gmail.com>
> Signed-off-by: Rodrigo Alencar <rodrigo.alencar@analog.com>
> ---
>  drivers/iio/dac/ad5686.c | 19 ++++++++-----------
>  1 file changed, 8 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/iio/dac/ad5686.c b/drivers/iio/dac/ad5686.c
> index 316f9ccf54d9..df32f46db81e 100644
> --- a/drivers/iio/dac/ad5686.c
> +++ b/drivers/iio/dac/ad5686.c
> @@ -8,6 +8,7 @@
>  #include <linux/array_size.h>
>  #include <linux/bitfield.h>
>  #include <linux/bitops.h>
> +#include <linux/cleanup.h>
>  #include <linux/delay.h>
>  #include <linux/dev_printk.h>
>  #include <linux/errno.h>
> @@ -177,11 +178,11 @@ static int ad5686_read_raw(struct iio_dev *indio_dev,
>  	struct ad5686_state *st = iio_priv(indio_dev);
>  	int ret;
>  
> +	guard(mutex)(&st->lock);

The commit message should explain why the location we are taking the lock
has moved. Although, I don't see a reason to move it.

> +
>  	switch (m) {
>  	case IIO_CHAN_INFO_RAW:
> -		mutex_lock(&st->lock);
>  		ret = ad5686_read(st, chan->address);
> -		mutex_unlock(&st->lock);
>  		if (ret < 0)
>  			return ret;
>  		*val = (ret >> chan->scan_type.shift) &
> @@ -202,23 +203,19 @@ static int ad5686_write_raw(struct iio_dev *indio_dev,
>  			    long mask)
>  {
>  	struct ad5686_state *st = iio_priv(indio_dev);
> -	int ret;
> +
> +	guard(mutex)(&st->lock);
>  
>  	switch (mask) {
>  	case IIO_CHAN_INFO_RAW:
>  		if (val >= (1 << chan->scan_type.realbits) || val < 0)
>  			return -EINVAL;
>  
> -		mutex_lock(&st->lock);
> -		ret = ad5686_write(st, AD5686_CMD_WRITE_INPUT_N_UPDATE_N,
> -				   chan->address, val << chan->scan_type.shift);
> -		mutex_unlock(&st->lock);
> -		break;
> +		return ad5686_write(st, AD5686_CMD_WRITE_INPUT_N_UPDATE_N,
> +				    chan->address, val << chan->scan_type.shift);
>  	default:
> -		ret = -EINVAL;
> +		return -EINVAL;
>  	}
> -
> -	return ret;
>  }
>  
>  static const struct iio_info ad5686_info = {
>