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From:   "Fabio M. De Francesco" <fmdefrancesco@gmail.com>
To:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        dan.carpenter@oracle.com
Cc:     David Kershner <david.kershner@unisys.com>,
        sparmaintainer@unisys.com, linux-staging@lists.linux.dev,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH] staging: unisys: Properly test debugfs_create_dir() return values
Date:   Tue, 29 Mar 2022 19:00:49 +0200
Message-ID: <2030244.KlZ2vcFHjT@leap>
In-Reply-To: <20220322083858.16887-1-fmdefrancesco@gmail.com>
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On marted=EC 22 marzo 2022 09:38:58 CEST Fabio M. De Francesco wrote:
> debugfs_create_dir() returns a pointers to a dentry objects. On failures
> it returns errors. Currently the values returned to visornic_probe()
> seem to be tested for being equal to NULL in case of failures.
>=20
> Properly test with "if (IS_ERR())" and then assign the correct error=20
> value to the "err" variable.
>=20
> Signed-off-by: Fabio M. De Francesco <fmdefrancesco@gmail.com>
> ---
>  drivers/staging/unisys/visornic/visornic_main.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>=20
> diff --git a/drivers/staging/unisys/visornic/visornic_main.c b/drivers/st=
aging/unisys/visornic/visornic_main.c
> index 643432458105..58d03f3d3173 100644
> --- a/drivers/staging/unisys/visornic/visornic_main.c
> +++ b/drivers/staging/unisys/visornic/visornic_main.c
> @@ -1922,11 +1922,11 @@ static int visornic_probe(struct visor_device *de=
v)
>  	/* create debug/sysfs directories */
>  	devdata->eth_debugfs_dir =3D debugfs_create_dir(netdev->name,
>  						      visornic_debugfs_dir);
> -	if (!devdata->eth_debugfs_dir) {
> +	if (IS_ERR(devdata->eth_debugfs_dir)) {
>  		dev_err(&dev->device,
>  			"%s debugfs_create_dir %s failed\n",
>  			__func__, netdev->name);
> -		err =3D -ENOMEM;
> +		err =3D PTR_ERR(devdata->eth_debugfs_dir);
>  		goto cleanup_register_netdev;
>  	}
> =20
> --=20
> 2.34.1
>=20
Hi Greg, Dan,

Now I have time to rework this patch but, if I'm not misunderstanding, you=
=20
asked for two contrasting works to do here...

Dan wrote that "[in] this case you can delete the whole devdata->eth_debugf=
s_dir=20
and the related code.".

Greg wrote that "We really shouldn't be checking this value at all.  There'=
s=20
no reason to check the return value of a debugfs_* call. Can you fix up the=
 code to
do that instead?".

I'm confused because they look like two incompatible requests. What should =
I do?

Thanks,

=46abio M. De Francesco