linux-kernel - Re: [PATCH v1] drivers:bus:Fix the NULL vs IS_ERR() bug for debugfs_create

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Message-ID: <babb0086-2299-4905-89dd-59e30e1f3c36@lunn.ch>
Date: Wed, 21 Aug 2024 14:31:15 +0200
From: Andrew Lunn <andrew@...n.ch>
To: Yang Ruibin <11162571@...o.com>
Cc: Sebastian Hesselbarth <sebastian.hesselbarth@...il.com>,
	Gregory Clement <gregory.clement@...tlin.com>,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	opensource.kernel@...o.com
Subject: Re: [PATCH v1] drivers:bus:Fix the NULL vs IS_ERR() bug for
 debugfs_create_dir()

On Wed, Aug 21, 2024 at 07:21:30AM -0400, Yang Ruibin wrote:
> The debugfs_create_dir() function returns error pointers.
> It never returns NULL. So use IS_ERR() to check it.
> 
> Signed-off-by: Yang Ruibin <11162571@...o.com>
> ---
>  drivers/bus/mvebu-mbus.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/bus/mvebu-mbus.c b/drivers/bus/mvebu-mbus.c
> index 3c99d72087eb..42621838ba75 100644
> --- a/drivers/bus/mvebu-mbus.c
> +++ b/drivers/bus/mvebu-mbus.c
> @@ -995,13 +995,13 @@ static __init int mvebu_mbus_debugfs_init(void)
>  	s->debugfs_root = debugfs_create_dir("mvebu-mbus", NULL);
>  	if(IS_ERR(s->debugfs_root))
>  		return PTR_ERR(s->debugfs_root);
> +

You are not supposed to check error codes from debugfs, since it is
optional. The code should just keep going, independent of failure or
success.

>  	s->debugfs_sdram = debugfs_create_file("sdram", S_IRUGO,
>  							s->debugfs_root, NULL,
>  							&mvebu_sdram_debug_fops);
>  	s->debugfs_devs = debugfs_create_file("devices", S_IRUGO,
>  							s->debugfs_root, NULL,
>  							&mvebu_devs_debug_fops);
> -	}

I'm surprised this code compiles without this close braces!

	Andrew