From f5c092787c48296633c2dd7240752f88fa9710fc Mon Sep 17 00:00:00 2001 From: Gabor Juhos Date: Sun, 1 Feb 2026 21:35:06 +0100 Subject: [PATCH] hwmon: (gpio-fan) Fix set_rpm() return value The set_rpm function is used as a 'store' callback of a device attribute, and as such it should return with the number of bytes consumed. However since commit 0d01110e6356 ("hwmon: (gpio-fan) Add regulator support"), the function returns with zero on success. Due to this, the function gets called again and again whenever the user tries to change the FAN speed by writing the desired RPM value into the 'fan1_target' sysfs attribute. The broken behaviour can be reproduced easily. For example, the following command never returns unless it gets terminated: $ echo 500 > /sys/class/hwmon/hwmon1/fan1_target ^C $ Change the code to return with the same value as the 'count' parameter on success to indicate that all bytes from the input buffer are consumed. The function behaved the same way prior to the offending change. Cc: stable@vger.kernel.org Fixes: 0d01110e6356 ("hwmon: (gpio-fan) Add regulator support") Signed-off-by: Gabor Juhos Link: https://lore.kernel.org/r/20260201-gpio-fan-set_rpm-retval-fix-v1-1-dc39bc7693ca@gmail.com Signed-off-by: Guenter Roeck --- drivers/hwmon/gpio-fan.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/hwmon/gpio-fan.c b/drivers/hwmon/gpio-fan.c index 516c34bb61c9c..d7fa021f376e3 100644 --- a/drivers/hwmon/gpio-fan.c +++ b/drivers/hwmon/gpio-fan.c @@ -291,7 +291,7 @@ static ssize_t set_rpm(struct device *dev, struct device_attribute *attr, { struct gpio_fan_data *fan_data = dev_get_drvdata(dev); unsigned long rpm; - int ret = count; + int ret; if (kstrtoul(buf, 10, &rpm)) return -EINVAL; @@ -308,7 +308,7 @@ static ssize_t set_rpm(struct device *dev, struct device_attribute *attr, exit_unlock: mutex_unlock(&fan_data->lock); - return ret; + return ret ? ret : count; } static DEVICE_ATTR_RW(pwm1); -- 2.47.3