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hwmon: (gpd-fan): fix race condition between device removal and sysfs access

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Replace the manual gpd_fan_remove() callback with a devres-managed
action using devm_add_action_or_reset(). The original remove hook
resets the fan to AUTOMATIC mode, but the hwmon sysfs interface
(registered with devm_hwmon_device_register_with_info()) remains
active until after the remove callback completes. This creates a
race window where a concurrent userspace sysfs access can interleave
with the EC I/O sequence, potentially corrupting EC registers.

Using devm_add_action_or_reset() registers the reset function as a
devres action. Due to the LIFO release order of devres, the hwmon
device is unregistered (sysfs removed) before the reset action
executes, eliminating the race condition.

Fixes: 0ab88e2394 ("hwmon: add GPD devices sensor driver")
Signed-off-by: Pei Xiao <xiaopei01@kylinos.cn>
Link: https://lore.kernel.org/r/4400828422cf3a88adad4db224d9efccdb1049d2.1781055639.git.xiaopei01@kylinos.cn
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
This commit is contained in:
Pei Xiao 2026-06-10 09:49:12 +08:00 committed by Guenter Roeck
parent 046e6e1a02
commit 1fb4397509
1 changed files with 16 additions and 11 deletions
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27
drivers/hwmon/gpd-fan.c
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@ -609,6 +609,16 @@ static void gpd_init_ec(struct gpd_fan_data *data)
gpd_win4_init_ec(data);
}
static void gpd_fan_reset_hardware(void *pdata)
{
struct gpd_fan_data *data = pdata;
if (data) {
data->pwm_enable = AUTOMATIC;
gpd_set_pwm_enable(data, AUTOMATIC);
}
}
static int gpd_fan_probe(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
@ -617,6 +627,7 @@ static int gpd_fan_probe(struct platform_device *pdev)
struct device *hwdev;
struct gpd_fan_data *data;
const struct gpd_fan_drvdata *match;
int ret;
res = platform_get_resource(pdev, IORESOURCE_IO, 0);
if (!res)
@ -644,6 +655,11 @@ static int gpd_fan_probe(struct platform_device *pdev)
dev_set_drvdata(dev, data);
gpd_init_ec(data);
ret = devm_add_action_or_reset(dev, gpd_fan_reset_hardware, data);
if (ret)
return ret;
hwdev = devm_hwmon_device_register_with_info(dev,
DRIVER_NAME,
data,
@ -655,19 +671,8 @@ static int gpd_fan_probe(struct platform_device *pdev)
return 0;
}
static void gpd_fan_remove(struct platform_device *pdev)
{
struct gpd_fan_data *data = dev_get_drvdata(&pdev->dev);
if (data) {
data->pwm_enable = AUTOMATIC;
gpd_set_pwm_enable(data, AUTOMATIC);
}
}
static struct platform_driver gpd_fan_driver = {
.probe = gpd_fan_probe,
.remove = gpd_fan_remove,
.driver = {
.name = KBUILD_MODNAME,
},