Re: [PATCH 1/2] platform/x86: dell-ddv: Fix cache invalidation on resume

Hans de Goede
2023-02-18T10:44:09Z

Hi Armin,

On 2/13/23 19:22, Armin Wolf wrote:
> If one or both sensor buffers could not be initialized, either
> due to missing hardware support or due to some error during probing,
> the resume handler will encounter undefined behaviour when
> attempting to lock buffers then protected by an uninitialized or
> destroyed mutex.
> Fix this by introducing a "active" flag which is set during probe,
> and only invalidate buffers which where flaged as "active".
>
> Tested on a Dell Inspiron 3505.
>
> Fixes: 3b7eeff93d29 ("platform/x86: dell-ddv: Add hwmon support")
> Signed-off-by: Armin Wolf <W_Armin@gmx.de>

Can you move the "if (...active)" check to inside
dell_wmi_ddv_hwmon_cache_invalidate() please ?

Otherwise this patch as well as patch 2/2 look good to me.

Regards,

Hans

> ---
> drivers/platform/x86/dell/dell-wmi-ddv.c | 12 +++++++++---
> 1 file changed, 9 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/platform/x86/dell/dell-wmi-ddv.c b/drivers/platform/x86/dell/dell-wmi-ddv.c
> index d547c9d09725..58f996b3b374 100644
> --- a/drivers/platform/x86/dell/dell-wmi-ddv.c
> +++ b/drivers/platform/x86/dell/dell-wmi-ddv.c
> @@ -96,6 +96,7 @@ struct combined_chip_info {
> };
>
> struct dell_wmi_ddv_sensors {
> + bool active;
> struct mutex lock; /* protect caching */
> unsigned long timestamp;
> union acpi_object *obj;
> @@ -530,6 +531,7 @@ static void dell_wmi_ddv_hwmon_cache_destroy(void *data)
> {
> struct dell_wmi_ddv_sensors *sensors = data;
>
> + sensors->active = false;
> mutex_destroy(&sensors->lock);
> kfree(sensors->obj);
> }
> @@ -549,6 +551,7 @@ static struct hwmon_channel_info *dell_wmi_ddv_channel_init(struct wmi_device *w
> return ERR_PTR(ret);
>
> mutex_init(&sensors->lock);
> + sensors->active = true;
>
> ret = devm_add_action_or_reset(&wdev->dev, dell_wmi_ddv_hwmon_cache_destroy, sensors);
> if (ret < 0)
> @@ -852,9 +855,12 @@ static int dell_wmi_ddv_resume(struct device *dev)
> {
> struct dell_wmi_ddv_data *data = dev_get_drvdata(dev);
>
> - /* Force re-reading of all sensors */
> - dell_wmi_ddv_hwmon_cache_invalidate(&data->fans);
> - dell_wmi_ddv_hwmon_cache_invalidate(&data->temps);
> + /* Force re-reading of all active sensors */
> + if (data->fans.active)
> + dell_wmi_ddv_hwmon_cache_invalidate(&data->fans);
> +
> + if (data->temps.active)
> + dell_wmi_ddv_hwmon_cache_invalidate(&data->temps);
>
> return 0;
> }
> --
> 2.30.2
>