linux-kernel - Re: [PATCH v7 4/4] gpiolib: Implement fast processing path in get/set array

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Date:   Thu, 20 Sep 2018 21:05:29 +0300
From:   Dan Carpenter <dan.carpenter@...cle.com>
To:     Janusz Krzysztofik <jmkrzyszt@...il.com>
Cc:     Marek Szyprowski <m.szyprowski@...sung.com>,
        Andrew Lunn <andrew@...n.ch>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        linux-doc@...r.kernel.org, linux-iio@...r.kernel.org,
        Linus Walleij <linus.walleij@...aro.org>,
        Dominik Brodowski <linux@...inikbrodowski.net>,
        Peter Rosin <peda@...ntia.se>, netdev@...r.kernel.org,
        linux-i2c@...r.kernel.org,
        Peter Meerwald-Stadler <pmeerw@...erw.net>,
        devel@...verdev.osuosl.org,
        Florian Fainelli <f.fainelli@...il.com>,
        Jonathan Corbet <corbet@....net>,
        Krzysztof Kozlowski <krzk@...nel.org>,
        Kishon Vijay Abraham I <kishon@...com>,
        Tony Lindgren <tony@...mide.com>,
        Lukas Wunner <lukas@...ner.de>,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        linux-serial@...r.kernel.org, Jiri Slaby <jslaby@...e.com>,
        Michael Hennerich <Michael.Hennerich@...log.com>,
        Uwe Kleine-König 
        <u.kleine-koenig@...gutronix.de>, linux-gpio@...r.kernel.org,
        Russell King <rmk+kernel@...linux.org.uk>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Yegor Yefremov <yegorslists@...glemail.com>,
        Sebastien Bourdelin <sebastien.bourdelin@...oirfairelinux.com>,
        "'Linux Samsung SOC'" <linux-samsung-soc@...r.kernel.org>,
        Rojhalat Ibrahim <imr@...chenk.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-mmc@...r.kernel.org, linux-kernel@...r.kernel.org,
        Willy Tarreau <w@....eu>,
        Miguel Ojeda Sandonis <miguel.ojeda.sandonis@...il.com>,
        Peter Korsgaard <peter.korsgaard@...co.com>,
        Hartmut Knaack <knaack.h@....de>,
        "David S. Miller" <davem@...emloft.net>,
        Jonathan Cameron <jic23@...nel.org>
Subject: Re: [PATCH v7 4/4] gpiolib: Implement fast processing path in
 get/set array

On Thu, Sep 20, 2018 at 05:48:22PM +0200, Janusz Krzysztofik wrote:
> diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
> index a53d17745d21..5bc3447949c9 100644
> --- a/drivers/gpio/gpiolib.c
> +++ b/drivers/gpio/gpiolib.c
> @@ -2880,7 +2880,7 @@ int gpiod_get_array_value_complex(bool raw, bool can_sleep,
>  			__set_bit(hwgpio, mask);
>  
>  			if (array_info)
> -				find_next_zero_bit(array_info->get_mask,
> +				i = find_next_zero_bit(array_info->get_mask,
>  						   array_size, i);

We could mark find_next_zero_bit() and friends as a __must_check
functions so we avoid this bug in the future.  I have a more complicated
idea how to detect these bugs in a generic way using Smatch but it will
take longer to implement.

regards,
dan carpenter