Re: [PATCH v1 1/3] gpiolib: sysfs: Move sysfs_emit() calls outside of the mutex lock

[Bartosz Golaszewski]

On Wed, Feb 9, 2022 at 12:31 PM Andy Shevchenko
<andriy.shevchenko@xxxxxxxxxxxxxxx> wrote:
>
> In a few places we perform sysfs_emit() operations under mutex that
> do not require any locking. Move them outside of the mutex locks.
>
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
> ---
>  drivers/gpio/gpiolib-sysfs.c | 29 ++++++++++++++---------------
>  1 file changed, 14 insertions(+), 15 deletions(-)
>
> diff --git a/drivers/gpio/gpiolib-sysfs.c b/drivers/gpio/gpiolib-sysfs.c
> index 78ca7dee8b64..57d8ecab53b7 100644
> --- a/drivers/gpio/gpiolib-sysfs.c
> +++ b/drivers/gpio/gpiolib-sysfs.c
> @@ -61,17 +61,16 @@ static ssize_t direction_show(struct device *dev,
>  {
>         struct gpiod_data *data = dev_get_drvdata(dev);
>         struct gpio_desc *desc = data->desc;
> -       ssize_t                 status;
> +       int value;
>
>         mutex_lock(&data->mutex);
>
>         gpiod_get_direction(desc);
> -       status = sysfs_emit(buf, "%s\n",
> -                           test_bit(FLAG_IS_OUT, &desc->flags) ? "out" : "in");
> +       value = !!test_bit(FLAG_IS_OUT, &desc->flags);
>
>         mutex_unlock(&data->mutex);
>
> -       return status;
> +       return sysfs_emit(buf, "%s\n", value ? "out" : "in");
>  }
>
>  static ssize_t direction_store(struct device *dev,
> @@ -108,12 +107,13 @@ static ssize_t value_show(struct device *dev,
>         mutex_lock(&data->mutex);
>
>         status = gpiod_get_value_cansleep(desc);
> -       if (status >= 0)
> -               status = sysfs_emit(buf, "%zd\n", status);
>
>         mutex_unlock(&data->mutex);
>
> -       return status;
> +       if (status < 0)
> +               return status;
> +
> +       return sysfs_emit(buf, "%zd\n", status);
>  }
>
>  static ssize_t value_store(struct device *dev,
> @@ -238,7 +238,6 @@ static ssize_t edge_show(struct device *dev,
>                 struct device_attribute *attr, char *buf)
>  {
>         struct gpiod_data *data = dev_get_drvdata(dev);
> -       ssize_t status = 0;
>         int i;
>
>         mutex_lock(&data->mutex);
> @@ -247,12 +246,13 @@ static ssize_t edge_show(struct device *dev,
>                 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);
>
> -       return status;
> +       if (i >= ARRAY_SIZE(trigger_types))
> +               return 0;
> +
> +       return sysfs_emit(buf, "%s\n", trigger_types[i].name);
>  }
>
>  static ssize_t edge_store(struct device *dev,
> @@ -324,16 +324,15 @@ static ssize_t active_low_show(struct device *dev,
>  {
>         struct gpiod_data *data = dev_get_drvdata(dev);
>         struct gpio_desc *desc = data->desc;
> -       ssize_t                 status;
> +       int value;
>
>         mutex_lock(&data->mutex);
>
> -       status = sysfs_emit(buf, "%d\n",
> -                           !!test_bit(FLAG_ACTIVE_LOW, &desc->flags));
> +       value = !!test_bit(FLAG_ACTIVE_LOW, &desc->flags);
>
>         mutex_unlock(&data->mutex);
>
> -       return status;
> +       return sysfs_emit(buf, "%d\n", value);
>  }
>
>  static ssize_t active_low_store(struct device *dev,
> --
> 2.34.1
>

Applied all three, thanks Andy!

Bart