Re: [PATCH] media: mc: mark the media devnode as registered from the, start

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Hi Hans,

Thanks for the patch.

On Fri, Feb 23, 2024 at 09:46:19AM +0100, Hans Verkuil wrote:
> First the media device node was created, and if successful it was
> marked as 'registered'. This leaves a small race condition where
> an application can open the device node and get an error back
> because the 'registered' flag was not yet set.
> 
> Change the order: first set the 'registered' flag, then actually
> register the media device node. If that fails, then clear the flag.
> 
> Signed-off-by: Hans Verkuil <hverkuil-cisco@xxxxxxxxx>

Acked-by: Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx>

> ---
>  drivers/media/mc/mc-devnode.c | 5 ++---
>  1 file changed, 2 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/media/mc/mc-devnode.c b/drivers/media/mc/mc-devnode.c
> index 7f67825c8757..318e267e798e 100644
> --- a/drivers/media/mc/mc-devnode.c
> +++ b/drivers/media/mc/mc-devnode.c
> @@ -245,15 +245,14 @@ int __must_check media_devnode_register(struct media_device *mdev,
>  	kobject_set_name(&devnode->cdev.kobj, "media%d", devnode->minor);
> 
>  	/* Part 3: Add the media and char device */
> +	set_bit(MEDIA_FLAG_REGISTERED, &devnode->flags);
>  	ret = cdev_device_add(&devnode->cdev, &devnode->dev);
>  	if (ret < 0) {
> +		clear_bit(MEDIA_FLAG_REGISTERED, &devnode->flags);
>  		pr_err("%s: cdev_device_add failed\n", __func__);
>  		goto cdev_add_error;
>  	}
> 
> -	/* Part 4: Activate this minor. The char device can now be used. */
> -	set_bit(MEDIA_FLAG_REGISTERED, &devnode->flags);
> -
>  	return 0;
> 
>  cdev_add_error:

-- 
Kind regards,

Sakari Ailus




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