linux-kernel - Re: [PATCH v1] lib:Fix an NULL vs IS_ERR() bug for debugfs_create_dir() in err_inject

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Message-ID: <2023071202-varsity-evasion-580b@gregkh>
Date:   Wed, 12 Jul 2023 18:34:48 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     Wang Ming <machel@...o.com>
Cc:     David Hildenbrand <david@...hat.com>,
        Akinobu Mita <akinobu.mita@...il.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        linux-kernel@...r.kernel.org, opensource.kernel@...o.com
Subject: Re: [PATCH v1] lib:Fix an NULL vs IS_ERR() bug for
 debugfs_create_dir() in err_inject_init()

On Wed, Jul 12, 2023 at 09:52:11PM +0800, Wang Ming wrote:
> The debugfs_create_dir() function returns error pointers.
> It never returns NULL. Most incorrect error checks were fixed,
> but the one in err_inject_init() was forgotten.
> 
> Fix the remaining error check.
> 
> Signed-off-by: Wang Ming <machel@...o.com>
> ---
>  lib/notifier-error-inject.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/lib/notifier-error-inject.c b/lib/notifier-error-inject.c
> index 2b24ea6c9497..c49354c23802 100644
> --- a/lib/notifier-error-inject.c
> +++ b/lib/notifier-error-inject.c
> @@ -83,7 +83,7 @@ static int __init err_inject_init(void)
>  	notifier_err_inject_dir =
>  		debugfs_create_dir("notifier-error-inject", NULL);
>  
> -	if (!notifier_err_inject_dir)
> +	if (IS_ERR(notifier_err_inject_dir))
>  		return -ENOMEM;

Please do not do any different codepath if a debugfs_*() call fails or
succeeds.

Why do you need to check this at all?

And why are you creating this directory at the root of debugfs?

thanks,

greg k-h