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

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Message-ID: <20200917122550.GA5053@pendragon.ideasonboard.com>
Date:   Thu, 17 Sep 2020 15:25:50 +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,

On Wed, Aug 19, 2020 at 02:47:19AM +0300, Laurent Pinchart wrote:
> 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.

Could yous share your opinion about this ?

> > 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