linux-kernel - Re: [PATCH] can: mpc5xxx_can: check of

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Message-ID: <20180709193157.GB17865@osadl.at>
Date:   Mon, 9 Jul 2018 19:31:57 +0000
From:   Nicholas Mc Guire <der.herr@...r.at>
To:     Fabio Estevam <festevam@...il.com>
Cc:     Nicholas Mc Guire <hofrat@...dl.org>,
        Wolfram Sang <w.sang@...gutronix.de>,
        Wolfgang Grandegger <wg@...ndegger.com>,
        Marc Kleine-Budde <mkl@...gutronix.de>,
        "David S. Miller" <davem@...emloft.net>, linux-can@...r.kernel.org,
        netdev <netdev@...r.kernel.org>,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] can: mpc5xxx_can: check of_iomap return before use

On Mon, Jul 09, 2018 at 04:28:41PM -0300, Fabio Estevam wrote:
> On Mon, Jul 9, 2018 at 4:16 PM, Nicholas Mc Guire <hofrat@...dl.org> wrote:
> >  of_iompa() can return NULL so that return needs to be checked and NULL
> 
> s/of_iompa/of_iomap/

sorry -  thats a stupid one.

> 
> > treated as failure. While at it also take care of the missing
> > of_node_put() in the error path.
> >
> > Signed-off-by: Nicholas Mc Guire <hofrat@...dl.org>
> > Fixes: commit afa17a500a36 ("net/can: add driver for mscan family & mpc52xx_mscan")
> > ---
> >
> > Problem was found by an experimental coccinelle script
> >
> > Patch was compiletested with: mpc5200_defconfig + CONFIG_CAN=y,
> > CONFIG_CAN_MSCAN=y, CONFIG_CAN_MPC5XXX=y
> > (with a number of sparse warnings not related to the proposed change)
> >
> > Patch is against 4.18-rc3 (localversion-next is next-20180706)
> >
> >  drivers/net/can/mscan/mpc5xxx_can.c | 5 +++++
> >  1 file changed, 5 insertions(+)
> >
> > diff --git a/drivers/net/can/mscan/mpc5xxx_can.c b/drivers/net/can/mscan/mpc5xxx_can.c
> > index c7427bd..2949a38 100644
> > --- a/drivers/net/can/mscan/mpc5xxx_can.c
> > +++ b/drivers/net/can/mscan/mpc5xxx_can.c
> > @@ -86,6 +86,11 @@ static u32 mpc52xx_can_get_clock(struct platform_device *ofdev,
> >                 return 0;
> >         }
> >         cdm = of_iomap(np_cdm, 0);
> > +       if (!cdm) {
> > +               of_node_put(np_cdm);
> > +               dev_err(&ofdev->dev, "can't map clock node!\n");
> > +               return 0;
> 
> I think you should return an error code here. -ENOMEM maybe?

I don´t think so the code above this part return 0 on error and a
valid frequency on success so returning -ENOMEM would probably be
mistaken as a frequency !

thx!
hofrat