Re: [PATCH v5] iio: adc: ad7280a: replace mutex_lock() with guard(mutex)

[Andy Shevchenko]

On Tue, Apr 21, 2026 at 04:08:55PM -0300, Matheus Giarola wrote:
> Use guard(mutex) instead of mutex_lock()/mutex_unlock(),
> ensuring the mutex is released automatically when leaving
> the function scope. The change improves error handling and
> avoids issues such as missing unlocks. It also simplifies the
> code by removing 'err_unlock' label and several mutex_unlock()
> calls.
> 
> As suggested, in ad7280_read_raw(), wrap the IIO_CHAN_INFO_RAW
> case in braces, providing a scope for the implicit variable
> declared by guard(mutex).
> 
> Also, limit guard(mutex) scope in ad7280_show_balance_timer()
> to keep it locked just when necessary.
> 
> In ad7280a_write_thresh(), replace break with return on error.

...

> static ssize_t ad7280_show_balance_timer(struct iio_dev *indio_dev,

>  	unsigned int msecs;
>  	int ret;
>  
> -	mutex_lock(&st->lock);
> -	ret = ad7280_read_reg(st, chan->address >> 8,
> +	scoped_guard(mutex, &st->lock) {
> +		ret = ad7280_read_reg(st, chan->address >> 8,
>  			      (chan->address & 0xFF) + AD7280A_CB1_TIMER_REG);
> -	mutex_unlock(&st->lock);
> +	}

Not sure if we need {} here (as it's one statement body), but the indentation
now got broken of the second line there.

What about

	u8 devaddr = chan->address >> 8;
	u8 addr = chan->address;
	// ...or use existing names in the driver for the same things

	scoped_guard(mutex, &st->lock)
		ret = ad7280_read_reg(st, devaddr, addr + AD7280A_CB1_TIMER_REG);

?

-- 
With Best Regards,
Andy Shevchenko