Re: [PATCH v2 1/5] iio: core: move to cleanup.h magic

From: Jonathan Cameron <jic23@kernel.org>
To: Nuno Sa <nuno.sa@analog.com>
Cc: <linux-iio@vger.kernel.org>, Lars-Peter Clausen <lars@metafoo.de>
Subject: Re: [PATCH v2 1/5] iio: core: move to cleanup.h magic
Date: Sun, 25 Feb 2024 12:36:00 +0000	[thread overview]
Message-ID: <20240225123600.301758b0@jic23-huawei> (raw)
In-Reply-To: <20240223-iio-use-cleanup-magic-v2-1-f6b4848c1f34@analog.com>

On Fri, 23 Feb 2024 13:43:44 +0100
Nuno Sa <nuno.sa@analog.com> wrote:

> 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>
> ---

> @@ -1808,29 +1805,22 @@ static long iio_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
>  	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 ret;

return -ENODEV; and drop initialisation above.

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