linux-kernel - Re: [PATCH v2] gpiolib: return 0 or 1 in gpiod_get

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CAJAp7OhsnS_ysO9W4Ordm+UTjvcoyYht1zR9yLqgcdto8C175A@mail.gmail.com>
Date:	Mon, 30 Nov 2015 12:05:49 -0800
From:	Bjorn Andersson <bjorn@...o.se>
To:	Jose Diaz de Grenu de Pedro <Jose.DiazdeGrenudePedro@...i.com>
Cc:	"linux-gpio@...r.kernel.org" <linux-gpio@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Linus Walleij <linus.walleij@...aro.org>,
	Alexandre Courbot <gnurou@...il.com>, hector.palacios@...i.com
Subject: Re: [PATCH v2] gpiolib: return 0 or 1 in gpiod_get_value*() functions

On Mon, Nov 30, 2015 at 9:30 AM, Jose Diaz de Grenu de Pedro
<Jose.DiazdeGrenudePedro@...i.com> wrote:
> Commit 79a9becda894 moved the awareness of active low state
> into the gpiod_get_value*() functions, but it only inverts the
> GPIO's raw value when it is active low. If the GPIO is active
> high, the gpiod_get_value*() functions return the raw value of
> the register, which can be any positive value.
>
> This patch does a double inversion when the GPIO is active high
> to make sure either 0 or 1 is returned by these functions.
>
> Signed-off-by: Jose Diaz de Grenu de Pedro <Jose.DiazdeGrenudePedro@...i.com>
> Signed-off-by: Hector Palacios <hector.palacios@...i.com>
> ---
> change in v2:
>  - add missing semicolon
> ---
>  drivers/gpio/gpiolib.c | 12 ++++++------
>  1 file changed, 6 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
> index 50c4922fe53a..bd96f0457ba8 100644
> --- a/drivers/gpio/gpiolib.c
> +++ b/drivers/gpio/gpiolib.c
> @@ -1981,9 +1981,9 @@ int gpiod_get_value(const struct gpio_desc *desc)
>
>         value = _gpiod_get_raw_value(desc);
>         if (test_bit(FLAG_ACTIVE_LOW, &desc->flags))
> -               value = !value;
> -
> -       return value;
> +               return !value;
> +       else
> +               return !!value;
>  }
>  EXPORT_SYMBOL_GPL(gpiod_get_value);

On linux-next (at least) _gpiod_get_raw_value() returns the following value:

value = value < 0 ? value : !!value;

So this should already be negative errno, 0 or 1.

Regards,
Bjorn
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/