linux-kernel - Re: [PATCH 3/8] platform: x86: dell-laptop: no need to check return value of debugfs

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Message-ID: <20190612122105.miyyfkmae24kddwt@pali>
Date:   Wed, 12 Jun 2019 14:21:05 +0200
From:   Pali Rohár <pali.rohar@...il.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     dvhart@...radead.org, andy@...radead.org,
        Matthew Garrett <mjg59@...f.ucam.org>,
        platform-driver-x86@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/8] platform: x86: dell-laptop: no need to check return
 value of debugfs_create functions

On Wednesday 12 June 2019 14:12:53 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: Matthew Garrett <mjg59@...f.ucam.org>
> Cc: "Pali Rohár" <pali.rohar@...il.com>
> Cc: Darren Hart <dvhart@...radead.org>
> Cc: Andy Shevchenko <andy@...radead.org>
> Cc: platform-driver-x86@...r.kernel.org
> Cc: linux-kernel@...r.kernel.org
> Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
> ---
>  drivers/platform/x86/dell-laptop.c | 5 ++---
>  1 file changed, 2 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/platform/x86/dell-laptop.c b/drivers/platform/x86/dell-laptop.c
> index a561f653cf13..94a2f259031c 100644
> --- a/drivers/platform/x86/dell-laptop.c
> +++ b/drivers/platform/x86/dell-laptop.c
> @@ -2176,9 +2176,8 @@ static int __init dell_init(void)
>  	kbd_led_init(&platform_device->dev);
>  
>  	dell_laptop_dir = debugfs_create_dir("dell_laptop", NULL);
> -	if (dell_laptop_dir != NULL)
> -		debugfs_create_file("rfkill", 0444, dell_laptop_dir, NULL,
> -				    &dell_debugfs_fops);
> +	debugfs_create_file("rfkill", 0444, dell_laptop_dir, NULL,
> +			    &dell_debugfs_fops);

Hi!

So... debugfs_create_dir() can return NULL, right?

And it is then OK to call
debugfs_create_file("rfkill", 0444, dell_laptop_dir, ...) with
dell_laptop_dir = NULL?

Where would be that "rfkill" file created?

>  
>  	dell_laptop_register_notifier(&dell_laptop_notifier);
>  

-- 
Pali Rohár
pali.rohar@...il.com