Re: [PATCH 6/9] thermal/core: Protect hwmon accesses to thermal operations with thermal zone mutex

[Rafael J. Wysocki]

On Mon, Oct 17, 2022 at 3:09 PM Guenter Roeck <linux@xxxxxxxxxxxx> wrote:
>
> In preparation to protecting access to thermal operations against thermal
> zone device removal, protect hwmon accesses to thermal zone operations
> with the thermal zone mutex. After acquiring the mutex, ensure that the
> thermal zone device is registered before proceeding.
>
> Signed-off-by: Guenter Roeck <linux@xxxxxxxxxxxx>
> ---
>  drivers/thermal/thermal_hwmon.c | 14 +++++++++++---
>  1 file changed, 11 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/thermal/thermal_hwmon.c b/drivers/thermal/thermal_hwmon.c
> index f53f4ceb6a5d..33bfbaed4236 100644
> --- a/drivers/thermal/thermal_hwmon.c
> +++ b/drivers/thermal/thermal_hwmon.c
> @@ -77,11 +77,19 @@ temp_crit_show(struct device *dev, struct device_attribute *attr, char *buf)
>         int temperature;
>         int ret;
>
> +       mutex_lock(&tz->lock);
> +
> +       if (!device_is_registered(&tz->device)) {
> +               ret = -ENODEV;
> +               goto unlock;
> +       }
> +
>         ret = tz->ops->get_crit_temp(tz, &temperature);

Again, I would do it this way:

        if (device_is_registered(&tz->device))
                ret = tz->ops->get_crit_temp(tz, &temperature);
        else
                ret = -ENODEV;

And I wouldn't change the code below (the ternary operator is out of
fashion in particular).

> -       if (ret)
> -               return ret;
>
> -       return sprintf(buf, "%d\n", temperature);
> +unlock:
> +       mutex_unlock(&tz->lock);
> +
> +       return ret ? ret : sprintf(buf, "%d\n", temperature);
>  }
>
>
> --