Re: [PATCH 1/5] iio: core: move to cleanup.h magic

[Jonathan Cameron <jic23@kernel.org>]

On Wed, 21 Feb 2024 14:26:52 +0100
Nuno Sa via B4 Relay <devnull+nuno.sa.analog.com@kernel.org> wrote:

> From: Nuno Sa <nuno.sa@analog.com>
> 
> Use the new cleanup magic for handling mutexes in IIO. This allows us to
> greatly simplify some code paths.
> 
> Note that we keep the plain mutex calls in the
> iio_device_release|acquire() APIs since in there the macros would likely
> not help much (as we want to keep the lock acquired when he leave the
> APIs).
> 
> Signed-off-by: Nuno Sa <nuno.sa@analog.com>
> ---
>  drivers/iio/industrialio-core.c | 52 +++++++++++++++--------------------------
>  1 file changed, 19 insertions(+), 33 deletions(-)
> 
> diff --git a/drivers/iio/industrialio-core.c b/drivers/iio/industrialio-core.c
> index 9b2877fe8689..7e6497828364 100644
> --- a/drivers/iio/industrialio-core.c
> +++ b/drivers/iio/industrialio-core.c
> @@ -11,6 +11,7 @@



> @@ -1806,31 +1803,22 @@ static long iio_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
>  	struct iio_dev *indio_dev = ib->indio_dev;
>  	struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
>  	struct iio_ioctl_handler *h;
> -	int ret = -ENODEV;
> -
> -	mutex_lock(&iio_dev_opaque->info_exist_lock);
>  
> +	guard(mutex)(&iio_dev_opaque->info_exist_lock);
>  	/*
>  	 * The NULL check here is required to prevent crashing when a device
>  	 * is being removed while userspace would still have open file handles
>  	 * to try to access this device.
>  	 */
>  	if (!indio_dev->info)
> -		goto out_unlock;
> +		return -ENODEV;
>  
>  	list_for_each_entry(h, &iio_dev_opaque->ioctl_handlers, entry) {
> -		ret = h->ioctl(indio_dev, filp, cmd, arg);
> -		if (ret != IIO_IOCTL_UNHANDLED)
> -			break;
> +		if (h->ioctl(indio_dev, filp, cmd, arg) != IIO_IOCTL_UNHANDLED)
> +			return 0;

Changes the return value if ret returns something other than IIO_IOCTL_UNHANDLED
which it can I think...

>  	}
>  
> -	if (ret == IIO_IOCTL_UNHANDLED)
> -		ret = -ENODEV;
> -
> -out_unlock:
> -	mutex_unlock(&iio_dev_opaque->info_exist_lock);
> -
> -	return ret;
> +	return -ENODEV;
>  }