linux-kernel - Re: [PATCH] lib: dynamic_debug: no need to check return value of debugfs

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Message-ID: <20190613174105.GA9415@kroah.com>
Date:   Thu, 13 Jun 2019 19:41:05 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     Jason Baron <jbaron@...mai.com>
Cc:     linux-kernel@...r.kernel.org
Subject: Re: [PATCH] lib: dynamic_debug: no need to check return value of
 debugfs_create functions

On Thu, Jun 13, 2019 at 12:09:00PM -0400, Jason Baron wrote:
> 
> 
> On 6/13/19 11:59 AM, Greg Kroah-Hartman wrote:
> > On Thu, Jun 13, 2019 at 10:33:23AM -0400, Jason Baron wrote:
> >> On 6/12/19 11:35 AM, 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.
> >>>
> >>> Cc: Jason Baron <jbaron@...mai.com>
> >>> Cc: linux-kernel@...r.kernel.org
> >>> Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
> >>> ---
> >>>  lib/dynamic_debug.c | 12 +++---------
> >>>  1 file changed, 3 insertions(+), 9 deletions(-)
> >>>
> >>> diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
> >>> index 8a16c2d498e9..c60409138e13 100644
> >>> --- a/lib/dynamic_debug.c
> >>> +++ b/lib/dynamic_debug.c
> >>> @@ -993,20 +993,14 @@ static __initdata int ddebug_init_success;
> >>>  
> >>>  static int __init dynamic_debug_init_debugfs(void)
> >>>  {
> >>> -	struct dentry *dir, *file;
> >>> +	struct dentry *dir;
> >>>  
> >>>  	if (!ddebug_init_success)
> >>>  		return -ENODEV;
> >>>  
> >>>  	dir = debugfs_create_dir("dynamic_debug", NULL);
> >>> -	if (!dir)
> >>> -		return -ENOMEM;
> >>> -	file = debugfs_create_file("control", 0644, dir, NULL,
> >>> -					&ddebug_proc_fops);
> >>> -	if (!file) {
> >>> -		debugfs_remove(dir);
> >>> -		return -ENOMEM;
> >>> -	}
> >>> +	debugfs_create_file("control", 0644, dir, NULL, &ddebug_proc_fops);
> >>> +
> >>>  	return 0;
> >>>  }
> >>>  
> >>>
> >>
> >> Looks like debugfs_create_dir() can return NULL,
> > 
> > No it can not.
> >
> 
> Ok, I looked at the wrong definition for failed_creating() :(

Yeah, tracefs should also probably change, it makes users of their api
easier...

> In that case:
> 
> Acked-by: Jason Baron <jbaron@...mai.com>

Wonderful, thanks for the review.

greg k-h