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

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Message-ID: <eee025e7-be05-92cb-854c-ece82eb23552@redhat.com>
Date:   Sat, 18 Feb 2023 11:43:11 +0100
From:   Hans de Goede <hdegoede@...hat.com>
To:     Armin Wolf <W_Armin@....de>, markgross@...nel.org
Cc:     jdelvare@...e.com, linux@...ck-us.net,
        platform-driver-x86@...r.kernel.org, linux-hwmon@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] platform/x86: dell-ddv: Fix cache invalidation on
 resume

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@....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
>