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From:   "Fabio M. De Francesco" <fmdefrancesco@gmail.com>
To:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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:   Thu, 24 Mar 2022 10:20:15 +0100
Message-ID: <3480204.R56niFO833@leap>
In-Reply-To: <YjmNIX4RsbG8LpyF@kroah.com>
References: <20220322083858.16887-1-fmdefrancesco@gmail.com> <YjmNIX4RsbG8LpyF@kroah.com>
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On marted? 22 marzo 2022 09:47:29 CET Greg Kroah-Hartman wrote:
> On Tue, Mar 22, 2022 at 09:38:58AM +0100, 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.
> > 
> > Properly test with "if (IS_ERR())" and then assign the correct error 
> > value to the "err" variable.
> > 
> > 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(-)
> > 
> > diff --git a/drivers/staging/unisys/visornic/visornic_main.c b/drivers/staging/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 *dev)
> >  	/* create debug/sysfs directories */
> >  	devdata->eth_debugfs_dir = debugfs_create_dir(netdev->name,
> >  						      visornic_debugfs_dir);
> > -	if (!devdata->eth_debugfs_dir) {
> > +	if (IS_ERR(devdata->eth_debugfs_dir)) {
> 
> We really shouldn't be checking this value at all.  There's no reason to
> check the return value of a debugfs_* call.  Can you fix up the code to
> do that instead?
> 
> thanks,
> 
> greg k-h
> 

Yes I'll do the work that you requested by this weekend, notwithstanding 
what I replied to Dan. 

While I reiterate all my considerations, it seems that, if not the people 
from Unisys, someone else still cares about this driver :)

Thanks,

Fabio