Re: [PATCH] staging: iio: impedance-analyzer: ad5933: use guard(mutex) in ad5933_show()

[Andy Shevchenko]

On Sun, Oct 18, 2026 at 08:01:27PM +0000, Nithishvelan M wrote:
> Use guard(mutex) to automatically manage the state lock in
> ad5933_show(). This simplifies the function by allowing direct returns
> from each switch case, eliminating the mutable return variables and
> manual mutex_unlock() calls.

...

>  	switch ((u32)this_attr->address) {
>  	case AD5933_OUT_RANGE:
> -		len = sysfs_emit(buf, "%u\n",
> -				 st->range_avail[(st->ctrl_hb >> 1) & 0x3]);
> -		break;
> +		return sysfs_emit(buf, "%u\n",
> +				  st->range_avail[(st->ctrl_hb >> 1) & 0x3]);

Keep it on a single (not so long) line.

		return sysfs_emit(buf, "%u\n", st->range_avail[(st->ctrl_hb >> 1) & 0x3]);

Most likely Sashiko might warn of use ctrl_hb variable as an index without
checking. So it might make sense to be prepared for that by adding a local
variable:

		unsigned int ridx = (st->ctrl_hb >> 1) & 0x03;

		return sysfs_emit(buf, "%u\n", st->range_avail[ridx]);


>  	case AD5933_OUT_RANGE_AVAIL:
> -		len = sysfs_emit(buf, "%u %u %u %u\n", st->range_avail[0],
> -				 st->range_avail[3], st->range_avail[2],
> -				 st->range_avail[1]);
> -		break;
> +		return sysfs_emit(buf, "%u %u %u %u\n", st->range_avail[0],
> +				  st->range_avail[3], st->range_avail[2],
> +				  st->range_avail[1]);

Split logically

		return sysfs_emit(buf, "%u %u %u %u\n",
				  st->range_avail[0], st->range_avail[3],
				  st->range_avail[2], st->range_avail[1]);

>  	case AD5933_OUT_SETTLING_CYCLES:
> -		len = sysfs_emit(buf, "%d\n", st->settling_cycles);
> -		break;
> +		return sysfs_emit(buf, "%d\n", st->settling_cycles);
>  	case AD5933_IN_PGA_GAIN:
> -		len = sysfs_emit(buf, "%s\n",
> -				 (st->ctrl_hb & AD5933_CTRL_PGA_GAIN_1) ?
> -				 "1" : "0.2");
> -		break;
> +		return sysfs_emit(buf, "%s\n",

> +				  (st->ctrl_hb & AD5933_CTRL_PGA_GAIN_1) ?
> +				  "1" : "0.2");

A single line

				  (st->ctrl_hb & AD5933_CTRL_PGA_GAIN_1) ?  "1" : "0.2");

and, IIRC the operator precedences, the parentheses can be dropped.

>  	case AD5933_IN_PGA_GAIN_AVAIL:
> -		len = sysfs_emit(buf, "1 0.2\n");
> -		break;
> +		return sysfs_emit(buf, "1 0.2\n");
>  	case AD5933_FREQ_POINTS:
> -		len = sysfs_emit(buf, "%d\n", st->freq_points);
> -		break;
> +		return sysfs_emit(buf, "%d\n", st->freq_points);
>  	default:
> -		ret = -EINVAL;
> +		return -EINVAL;
>  	}

-- 
With Best Regards,
Andy Shevchenko