Re: [PATCH 2/5] staging: iio: ad9832: convert to guard(mutex)

[Marcelo Schmitt <marcelo.schmitt1@gmail.com>]

On 12/15, Tomas Borquez wrote:
> Use guard(mutex) for cleaner lock handling and simpler error paths.
> 
> Signed-off-by: Tomas Borquez <tomasborquez13@gmail.com>
> ---
>  drivers/staging/iio/frequency/ad9832.c | 28 +++++++++++---------------
>  1 file changed, 12 insertions(+), 16 deletions(-)
> 
> diff --git a/drivers/staging/iio/frequency/ad9832.c b/drivers/staging/iio/frequency/ad9832.c
> index 00813dab7c..f9ef3aede4 100644
> --- a/drivers/staging/iio/frequency/ad9832.c
> +++ b/drivers/staging/iio/frequency/ad9832.c
> @@ -9,6 +9,7 @@
>  
...
> -	mutex_lock(&st->lock);
> +	guard(mutex)(&st->lock);
>  	switch ((u32)this_attr->address) {
>  	case AD9832_FREQ0HM:
>  	case AD9832_FREQ1HM:
> @@ -203,22 +205,18 @@ static ssize_t ad9832_write(struct device *dev, struct device_attribute *attr,
>  		ret = spi_sync(st->spi, &st->msg);
>  		break;
>  	case AD9832_FREQ_SYM:
> -		if (val == 1 || val == 0) {
> -			st->ctrl_fp &= ~AD9832_FREQ;
> -			st->ctrl_fp |= FIELD_PREP(AD9832_FREQ, val ? 1 : 0);
> -		} else {
> -			ret = -EINVAL;
> -			break;
> -		}
> +		if (val != 1 && val != 0)
> +			return -EINVAL;
> +
> +		st->ctrl_fp &= ~AD9832_FREQ;
> +		st->ctrl_fp |= FIELD_PREP(AD9832_FREQ, val ? 1 : 0);
>  		st->data = cpu_to_be16(FIELD_PREP(AD9832_CMD_MSK, AD9832_CMD_FPSELECT) |
>  						  st->ctrl_fp);
>  		ret = spi_sync(st->spi, &st->msg);
>  		break;
Since we now have the mutex unlock handled by guard, why not returning directly
from each case?
E.g.
	case AD9832_FREQ1HM:
-		ret = ad9832_write_frequency(st, this_attr->address, val);
-		break;
+		return ad9832_write_frequency(st, this_attr->address, val);
I think the last return (outside the default clause) won't be needed anymore.


And, since you are touching the lock, you may also update to use
devm_mutex_init() (that would probably be best appreciated as a separate patch).

>  	case AD9832_PHASE_SYM:
> -		if (val > 3) {
> -			ret = -EINVAL;
> -			break;
> -		}
> +		if (val > 3)
> +			return -EINVAL;