Hello,
On Wed, Feb 13, 2013 at 04:03:00PM +0900, Alexandre Courbot wrote:
> From: Alexandre Courbot <[email protected]>
>
> Constify descriptor parameter of gpiod_* functions for those that
> should obviously not modify it. This includes value or direction get,
> cansleep, and IRQ number query.
>
> Signed-off-by: Alexandre Courbot <[email protected]>
This patch is applied as def634338d3ffb32fbe9b0a2d70cc24ef909cd4f since
v3.9-rc2.
> drivers/gpio/gpiolib.c | 29 ++++++++++++++++-------------
> 1 file changed, 16 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
> index 8a2cf9c..ad6df6b 100644
> --- a/drivers/gpio/gpiolib.c
> +++ b/drivers/gpio/gpiolib.c
> @@ -207,7 +208,7 @@ static int gpiochip_find_base(int ngpio)
> }
>
> /* caller ensures gpio is valid and requested, chip->get_direction may sleep
> */
> -static int gpiod_get_direction(struct gpio_desc *desc)
> +static int gpiod_get_direction(const struct gpio_desc *desc)
> {
> struct gpio_chip *chip;
> unsigned offset;
> @@ -223,11 +224,13 @@ static int gpiod_get_direction(struct gpio_desc *desc)
> if (status > 0) {
> /* GPIOF_DIR_IN, or other positive */
> status = 1;
> - clear_bit(FLAG_IS_OUT, &desc->flags);
> + /* FLAG_IS_OUT is just a cache of the result of get_direction(),
> + * so it does not affect constness per se */
> + clear_bit(FLAG_IS_OUT, &((struct gpio_desc *)desc)->flags);
I think this is worse than not having gpiod_get_direction take a const
descriptor.
I don't know an example for this particular case where this could break,
but usually casting away a const is bad and can break in various ways.
Maybe even drop the public function gpiod_get_direction completely.
As of next-20141114 there are only two users of this function (apart
from drivers/gpio/gpiolib*) and both are wrong (as discussed in
http://thread.gmane.org/gmane.linux.serial/16808/focus=4783).
Best regards
Uwe
--
Pengutronix e.K. | Uwe Kleine-König |
Industrial Linux Solutions | http://www.pengutronix.de/ |
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