linux-kernel - RE: [PATCH] gpio: mpc8xxx: resolve coverity warnings

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Message-ID: <DB6PR0401MB243884BFCB97E719642385FA8FF20@DB6PR0401MB2438.eurprd04.prod.outlook.com>
Date:   Thu, 3 Dec 2020 08:07:17 +0000
From:   "Biwen Li (OSS)" <biwen.li@....nxp.com>
To:     Bartosz Golaszewski <bgolaszewski@...libre.com>,
        "Biwen Li (OSS)" <biwen.li@....nxp.com>
CC:     Leo Li <leoyang.li@....com>, Aisheng Dong <aisheng.dong@....com>,
        LKML <linux-kernel@...r.kernel.org>,
        Jiafei Pan <jiafei.pan@....com>,
        linux-gpio <linux-gpio@...r.kernel.org>
Subject: RE: [PATCH] gpio: mpc8xxx: resolve coverity warnings

> On Thu, Dec 3, 2020 at 8:31 AM Biwen Li <biwen.li@....nxp.com> wrote:
> >
> > From: Biwen Li <biwen.li@....com>
> >
> > Resolve coverity warnings as follows,
> >     cond_at_most: Checking gpio >= 28U implies that gpio may be up
> >     to 27 on the false branch.
> >     overrun-call: Overrunning callees array of size 3 by passing
> >     argument gpio (which evaluates to 27)
> >     in call to *mpc8xxx_gc->direction_output
> >
> >     cond_at_least: Checking gpio <= 3U implies that gpio is at least 4 on
> >     the false branch.
> >     overrun-call: Overrunning callee's array of size 3 by passing argument
> >     gpio (which evaluates to 4) in call to
> > *mpc8xxx_gc->direction_output
> >
> > Signed-off-by: Biwen Li <biwen.li@....com>
> > ---
> >  drivers/gpio/gpio-mpc8xxx.c | 5 +++--
> >  1 file changed, 3 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/gpio/gpio-mpc8xxx.c b/drivers/gpio/gpio-mpc8xxx.c
> > index a6c2bbdcaa10..12c9a91d87b7 100644
> > --- a/drivers/gpio/gpio-mpc8xxx.c
> > +++ b/drivers/gpio/gpio-mpc8xxx.c
> > @@ -3,6 +3,7 @@
> >   *
> >   * Copyright (C) 2008 Peter Korsgaard <jacmet@...site.dk>
> >   * Copyright (C) 2016 Freescale Semiconductor Inc.
> > + * Copyright 2020 NXP
> 
> A copyright notice on a two-line change is a bit too much, don't you think?
Okay, got it. Will remove it in v2.
> 
> >   *
> >   * This file is licensed under the terms of the GNU General Public License
> >   * version 2.  This program is licensed "as is" without any warranty
> > of any @@ -80,7 +81,7 @@ static int mpc5121_gpio_dir_out(struct
> > gpio_chip *gc,  {
> >         struct mpc8xxx_gpio_chip *mpc8xxx_gc = gpiochip_get_data(gc);
> >         /* GPIO 28..31 are input only on MPC5121 */
> > -       if (gpio >= 28)
> > +       if (gpio >= 28U)
> >                 return -EINVAL;
> 
> I don't really understand the commit message but looking at the code is even
> more confusing. What are you fixing here actually?
Try to fix code warning that generated by coverity scan tool(static code analysis tool)
> 
> Bartosz
> 
> >
> >         return mpc8xxx_gc->direction_output(gc, gpio, val); @@ -91,7
> > +92,7 @@ static int mpc5125_gpio_dir_out(struct gpio_chip *gc,  {
> >         struct mpc8xxx_gpio_chip *mpc8xxx_gc = gpiochip_get_data(gc);
> >         /* GPIO 0..3 are input only on MPC5125 */
> > -       if (gpio <= 3)
> > +       if (gpio <= 3U)
> >                 return -EINVAL;
> >
> >         return mpc8xxx_gc->direction_output(gc, gpio, val);
> > --
> > 2.17.1
> >