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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20190122160759.mx3h7gjc23zmrvxc@linutronix.de>
Date:   Tue, 22 Jan 2019 17:07:59 +0100
From:   Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     linux-kernel@...r.kernel.org,
        Andrew Morton <akpm@...ux-foundation.org>,
        Anders Roxell <anders.roxell@...aro.org>,
        Arnd Bergmann <arnd@...db.de>, Michal Hocko <mhocko@...e.com>,
        linux-mm@...ck.org
Subject: Re: [PATCH] backing-dev: no need to check return value of
 debugfs_create functions

On 2019-01-22 16:21:07 [+0100], Greg Kroah-Hartman wrote:
> diff --git a/mm/backing-dev.c b/mm/backing-dev.c
> index 8a8bb8796c6c..85ef344a9c67 100644
> --- a/mm/backing-dev.c
> +++ b/mm/backing-dev.c
> @@ -102,39 +102,25 @@ static int bdi_debug_stats_show(struct seq_file *m, void *v)
>  }
>  DEFINE_SHOW_ATTRIBUTE(bdi_debug_stats);
>  
> -static int bdi_debug_register(struct backing_dev_info *bdi, const char *name)
> +static void bdi_debug_register(struct backing_dev_info *bdi, const char *name)
>  {
> -	if (!bdi_debug_root)
> -		return -ENOMEM;
> -
>  	bdi->debug_dir = debugfs_create_dir(name, bdi_debug_root);

If this fails then ->debug_dir is NULL 

> -	if (!bdi->debug_dir)
> -		return -ENOMEM;
> -
> -	bdi->debug_stats = debugfs_create_file("stats", 0444, bdi->debug_dir,
> -					       bdi, &bdi_debug_stats_fops);
> -	if (!bdi->debug_stats) {
> -		debugfs_remove(bdi->debug_dir);
> -		bdi->debug_dir = NULL;
> -		return -ENOMEM;
> -	}
>  
> -	return 0;
> +	debugfs_create_file("stats", 0444, bdi->debug_dir, bdi,
> +			    &bdi_debug_stats_fops);

then this creates the stats file in the root folder and

>  }
>  
>  static void bdi_debug_unregister(struct backing_dev_info *bdi)
>  {
> -	debugfs_remove(bdi->debug_stats);
> -	debugfs_remove(bdi->debug_dir);
> +	debugfs_remove_recursive(bdi->debug_dir);

this won't remove it.

If you return for "debug_dir == NULL" then it is a nice cleanup.

Sebastian