linux-kernel - Re: [PATCH 7/7] media: usb: uvc: no need to check return value of debugfs

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Message-ID: <20200818234719.GD2360@pendragon.ideasonboard.com>
Date:   Wed, 19 Aug 2020 02:47:19 +0300
From:   Laurent Pinchart <laurent.pinchart@...asonboard.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     linux-media@...r.kernel.org,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 7/7] media: usb: uvc: no need to check return value of
 debugfs_create functions

Hi Greg,

Thank you for the patch.

On Tue, Aug 18, 2020 at 03:36:08PM +0200, Greg Kroah-Hartman wrote:
> When calling debugfs functions, there is no need to ever check the
> return value.  The function can work or not, but the code logic should
> never do something different based on this.

Is there no value in warning the user that something went wrong ? Silent
failures are harder to debug.

> Cc: Laurent Pinchart <laurent.pinchart@...asonboard.com>
> Cc: Mauro Carvalho Chehab <mchehab@...nel.org>
> Cc: linux-media@...r.kernel.org
> Cc: linux-kernel@...r.kernel.org
> Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
> ---
>  drivers/media/usb/uvc/uvc_debugfs.c | 20 ++++----------------
>  1 file changed, 4 insertions(+), 16 deletions(-)
> 
> diff --git a/drivers/media/usb/uvc/uvc_debugfs.c b/drivers/media/usb/uvc/uvc_debugfs.c
> index 2b8af4b54117..1a1258d4ffca 100644
> --- a/drivers/media/usb/uvc/uvc_debugfs.c
> +++ b/drivers/media/usb/uvc/uvc_debugfs.c
> @@ -73,7 +73,6 @@ static struct dentry *uvc_debugfs_root_dir;
>  void uvc_debugfs_init_stream(struct uvc_streaming *stream)
>  {
>  	struct usb_device *udev = stream->dev->udev;
> -	struct dentry *dent;
>  	char dir_name[33];
>  
>  	if (uvc_debugfs_root_dir == NULL)
> @@ -82,22 +81,11 @@ void uvc_debugfs_init_stream(struct uvc_streaming *stream)
>  	snprintf(dir_name, sizeof(dir_name), "%u-%u-%u", udev->bus->busnum,
>  		 udev->devnum, stream->intfnum);
>  
> -	dent = debugfs_create_dir(dir_name, uvc_debugfs_root_dir);
> -	if (IS_ERR_OR_NULL(dent)) {
> -		uvc_printk(KERN_INFO, "Unable to create debugfs %s "
> -			   "directory.\n", dir_name);
> -		return;
> -	}
> -
> -	stream->debugfs_dir = dent;
> +	stream->debugfs_dir = debugfs_create_dir(dir_name,
> +						 uvc_debugfs_root_dir);
>  
> -	dent = debugfs_create_file("stats", 0444, stream->debugfs_dir,
> -				   stream, &uvc_debugfs_stats_fops);
> -	if (IS_ERR_OR_NULL(dent)) {
> -		uvc_printk(KERN_INFO, "Unable to create debugfs stats file.\n");
> -		uvc_debugfs_cleanup_stream(stream);
> -		return;
> -	}
> +	debugfs_create_file("stats", 0444, stream->debugfs_dir, stream,
> +			    &uvc_debugfs_stats_fops);
>  }
>  
>  void uvc_debugfs_cleanup_stream(struct uvc_streaming *stream)

-- 
Regards,

Laurent Pinchart