linux-kernel - Re: [PATCH v1 1/1] gpiolib: Use sysfs

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Date:   Fri, 21 May 2021 14:55:30 +0200
From:   Bartosz Golaszewski <bgolaszewski@...libre.com>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc:     linux-gpio <linux-gpio@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Linus Walleij <linus.walleij@...aro.org>
Subject: Re: [PATCH v1 1/1] gpiolib: Use sysfs_emit() in "show" functions

On Tue, May 18, 2021 at 2:09 PM Andy Shevchenko
<andriy.shevchenko@...ux.intel.com> wrote:
>
> The sysfs_emit() function was introduced to make it less ambiguous
> which function is preferred when writing to the output buffer in
> a "show" callback [1].
>
> Convert the GPIO library sysfs interface from sprintf() to sysfs_emit()
> accordingly, as the latter is aware of the PAGE_SIZE buffer and correctly
> returns the number of bytes written into the buffer.
>
> No functional change intended.
>
> [1] Documentation/filesystems/sysfs.rst
>
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
> ---
>  drivers/gpio/gpiolib-sysfs.c | 27 ++++++++++-----------------
>  1 file changed, 10 insertions(+), 17 deletions(-)
>
> diff --git a/drivers/gpio/gpiolib-sysfs.c b/drivers/gpio/gpiolib-sysfs.c
> index 7c5afd999210..d836aba91d3c 100644
> --- a/drivers/gpio/gpiolib-sysfs.c
> +++ b/drivers/gpio/gpiolib-sysfs.c
> @@ -66,9 +66,7 @@ static ssize_t direction_show(struct device *dev,
>         mutex_lock(&data->mutex);
>
>         gpiod_get_direction(desc);
> -       status = sprintf(buf, "%s\n",
> -                       test_bit(FLAG_IS_OUT, &desc->flags)
> -                               ? "out" : "in");
> +       status = sysfs_emit(buf, "%s\n", test_bit(FLAG_IS_OUT, &desc->flags) ? "out" : "in");
>
>         mutex_unlock(&data->mutex);
>
> @@ -109,13 +107,9 @@ static ssize_t value_show(struct device *dev,
>         mutex_lock(&data->mutex);
>
>         status = gpiod_get_value_cansleep(desc);
> -       if (status < 0)
> -               goto err;
> +       if (status >= 0)
> +               status = sysfs_emit(buf, "%zd\n", status);
>
> -       buf[0] = '0' + status;
> -       buf[1] = '\n';
> -       status = 2;
> -err:
>         mutex_unlock(&data->mutex);
>
>         return status;
> @@ -249,11 +243,11 @@ static ssize_t edge_show(struct device *dev,
>         mutex_lock(&data->mutex);
>
>         for (i = 0; i < ARRAY_SIZE(trigger_types); i++) {
> -               if (data->irq_flags == trigger_types[i].flags) {
> -                       status = sprintf(buf, "%s\n", trigger_types[i].name);
> +               if (data->irq_flags == trigger_types[i].flags)
>                         break;
> -               }
>         }
> +       if (i < ARRAY_SIZE(trigger_types))
> +               status = sysfs_emit(buf, "%s\n", trigger_types[i].name);
>
>         mutex_unlock(&data->mutex);
>
> @@ -333,8 +327,7 @@ static ssize_t active_low_show(struct device *dev,
>
>         mutex_lock(&data->mutex);
>
> -       status = sprintf(buf, "%d\n",
> -                               !!test_bit(FLAG_ACTIVE_LOW, &desc->flags));
> +       status = sysfs_emit(buf, "%d\n", !!test_bit(FLAG_ACTIVE_LOW, &desc->flags));
>
>         mutex_unlock(&data->mutex);
>
> @@ -412,7 +405,7 @@ static ssize_t base_show(struct device *dev,
>  {
>         const struct gpio_chip  *chip = dev_get_drvdata(dev);
>
> -       return sprintf(buf, "%d\n", chip->base);
> +       return sysfs_emit(buf, "%d\n", chip->base);
>  }
>  static DEVICE_ATTR_RO(base);
>
> @@ -421,7 +414,7 @@ static ssize_t label_show(struct device *dev,
>  {
>         const struct gpio_chip  *chip = dev_get_drvdata(dev);
>
> -       return sprintf(buf, "%s\n", chip->label ? : "");
> +       return sysfs_emit(buf, "%s\n", chip->label ?: "");
>  }
>  static DEVICE_ATTR_RO(label);
>
> @@ -430,7 +423,7 @@ static ssize_t ngpio_show(struct device *dev,
>  {
>         const struct gpio_chip  *chip = dev_get_drvdata(dev);
>
> -       return sprintf(buf, "%u\n", chip->ngpio);
> +       return sysfs_emit(buf, "%u\n", chip->ngpio);
>  }
>  static DEVICE_ATTR_RO(ngpio);
>
> --
> 2.30.2
>

Applied, thanks!

Bartosz