Re: [PATCH v3] iio: magnetometer: bmc150_magn: Used guard() for mutex protection

[Jonathan Cameron <jic23@kernel.org>]

On Tue,  3 Feb 2026 21:12:41 -0500
Neel Bullywon <neelb2403@gmail.com> wrote:

> Replaced the manual mutex lock/unlock calls using guard() to simplify
> the error handling and reduce goto statement usage.
> 
> By using RAII-style cleanup, it ensures the mutex is always released
> when exiting the function, regardless of the return path taken.
> 
> Signed-off-by: Neel Bullywon <neelb2403@gmail.com>
> Reviewed-by: David Lechner <dlechner@baylibre.com>
> Reviewed-by: Andy Shevchenko <andriy.shevchenko@intel.com>
Looks like this needs to have 
#include <linux/cleanup.h>
as first use of this stuff in this particular file.

From a quick look it seems to me that there might be other potential
similar cases in this file that would make sense to include as part of this
patch.  Perhaps you could take a look at those?

In some places it is in a switch statement so you'd have to
add {} to define the scope, or use scoped_guard() as appropriate.

Thanks,

Jonathan

> ---
>  drivers/iio/magnetometer/bmc150_magn.c | 21 +++++++--------------
>  1 file changed, 7 insertions(+), 14 deletions(-)
> 
> diff --git a/drivers/iio/magnetometer/bmc150_magn.c b/drivers/iio/magnetometer/bmc150_magn.c
> index 6a73f6e2f1f0..bd2706c2078d 100644
> --- a/drivers/iio/magnetometer/bmc150_magn.c
> +++ b/drivers/iio/magnetometer/bmc150_magn.c
> @@ -794,32 +794,25 @@ static int bmc150_magn_data_rdy_trigger_set_state(struct iio_trigger *trig,
>  {
>  	struct iio_dev *indio_dev = iio_trigger_get_drvdata(trig);
>  	struct bmc150_magn_data *data = iio_priv(indio_dev);
> -	int ret = 0;
> +	int ret;
> +
> +	guard(mutex)(&data->mutex);
>  
> -	mutex_lock(&data->mutex);
>  	if (state == data->dready_trigger_on)
> -		goto err_unlock;
> +		return 0;
>  
>  	ret = regmap_update_bits(data->regmap, BMC150_MAGN_REG_INT_DRDY,
>  				 BMC150_MAGN_MASK_DRDY_EN,
>  				 state << BMC150_MAGN_SHIFT_DRDY_EN);
>  	if (ret < 0)
> -		goto err_unlock;
> +		return ret;
>  
>  	data->dready_trigger_on = state;
>  
> -	if (state) {
> -		ret = bmc150_magn_reset_intr(data);
> -		if (ret < 0)
> -			goto err_unlock;
> -	}
> -	mutex_unlock(&data->mutex);
> +	if (state)
> +		return bmc150_magn_reset_intr(data);
>  
>  	return 0;
> -
> -err_unlock:
> -	mutex_unlock(&data->mutex);
> -	return ret;
>  }
>  
>  static const struct iio_trigger_ops bmc150_magn_trigger_ops = {