linux-kernel - Re: [PATCH v1 2/4] hwmon: (acpi_power_meter) Fix update the power trip points on failure

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Message-ID: <7acbc41a-f822-4464-8bcb-b7379fa78a86@roeck-us.net>
Date: Mon, 25 Nov 2024 07:22:55 -0800
From: Guenter Roeck <linux@...ck-us.net>
To: Huisong Li <lihuisong@...wei.com>, linux-hwmon@...r.kernel.org,
 linux-kernel@...r.kernel.org
Cc: jdelvare@...e.com, liuyonglong@...wei.com, zhanjie9@...ilicon.com,
 zhenglifeng1@...wei.com
Subject: Re: [PATCH v1 2/4] hwmon: (acpi_power_meter) Fix update the power
 trip points on failure

On 11/25/24 01:34, Huisong Li wrote:
> The power trip points maintained in local should not be updated when '_PTP'
> method fails to evaluate.
> 
> Signed-off-by: Huisong Li <lihuisong@...wei.com>
> ---
>   drivers/hwmon/acpi_power_meter.c | 5 ++++-
>   1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/hwmon/acpi_power_meter.c b/drivers/hwmon/acpi_power_meter.c
> index 4c3314e35d30..95da73858a0b 100644
> --- a/drivers/hwmon/acpi_power_meter.c
> +++ b/drivers/hwmon/acpi_power_meter.c
> @@ -292,8 +292,8 @@ static ssize_t set_trip(struct device *dev, struct device_attribute *devattr,
>   	struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
>   	struct acpi_device *acpi_dev = to_acpi_device(dev);
>   	struct acpi_power_meter_resource *resource = acpi_dev->driver_data;
> +	unsigned long temp, trip_bk;
>   	int res;
> -	unsigned long temp;
>   
>   	res = kstrtoul(buf, 10, &temp);
>   	if (res)
> @@ -302,8 +302,11 @@ static ssize_t set_trip(struct device *dev, struct device_attribute *devattr,
>   	temp = DIV_ROUND_CLOSEST(temp, 1000);
>   
>   	mutex_lock(&resource->lock);
> +	trip_bk = resource->trip[attr->index - 7];
>   	resource->trip[attr->index - 7] = temp;
>   	res = set_acpi_trip(resource);
> +	if (!res)
> +		resource->trip[attr->index - 7] = trip_bk;

Unless I am missing something, this restores the old value if setting
the new value succeeded. Please explain.

Thanks,
Guenter

>   	mutex_unlock(&resource->lock);
>   
>   	if (res)