linux-kernel - Re: [PATCH 09/10] gpiolib: use gpiochip_dup_line_label() in for

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Date:   Wed, 29 Nov 2023 15:43:32 +0100
From:   Bartosz Golaszewski <brgl@...ev.pl>
To:     Linus Walleij <linus.walleij@...aro.org>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc:     linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org,
        Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
Subject: Re: [PATCH 09/10] gpiolib: use gpiochip_dup_line_label() in for_each helpers

On Wed, Nov 29, 2023 at 3:24 PM Bartosz Golaszewski <brgl@...ev.pl> wrote:
>
> From: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
>
> Rework for_each_requested_gpio_in_range() to use the new helper to
> retrieve a dynamically allocated copy of the descriptor label and free
> it at the end of each iteration.
>
> Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
> ---
>  include/linux/gpio/driver.h | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/include/linux/gpio/driver.h b/include/linux/gpio/driver.h
> index 9796a34e2fee..6405f6d454af 100644
> --- a/include/linux/gpio/driver.h
> +++ b/include/linux/gpio/driver.h
> @@ -543,8 +543,10 @@ char *gpiochip_dup_line_label(struct gpio_chip *gc, unsigned int offset);
>   * @label:     label of current GPIO
>   */
>  #define for_each_requested_gpio_in_range(chip, i, base, size, label)                   \
> -       for (i = 0; i < size; i++)                                                      \
> -               if ((label = gpiochip_is_requested(chip, base + i)) == NULL) {} else
> +       for (i = 0; i < size; i++, kfree(label))                                        \
> +               if ((label = gpiochip_dup_line_label(chip, base + i)) == NULL) {}       \
> +               else if (IS_ERR(label)) {}                                              \
> +               else
>

Ah, cr*p, it will leak if we break out of the loop, why did I think it
was correct?

Any ideas how to handle this one? I was thinking something like:

    for (i = 0, char *p __free(kfree) = label; i < size; i++)

would work but it doesn't.

Bart

>  /* Iterates over all requested GPIO of the given @chip */
>  #define for_each_requested_gpio(chip, i, label)                                                \
> --
> 2.40.1
>