Commit 8887516f authored by Li Zhong's avatar Li Zhong Committed by Guenter Roeck
Browse files

hwmon: (adm9240) fix data race in adm9240_fan_read 



In
adm9240_read()
  adm9240_fan_read()
    adm9240_write_fan_div(),

it assumes that the caller of adm9240_write_fan_div() must hold
data->update_lock. Otherwise, it may cause data races when data is
updated by other threads.

Signed-off-by: default avatarLi Zhong <floridsleeves@gmail.com>
Link: https://lore.kernel.org/r/20220924001751.1726369-1-floridsleeves@gmail.com


Signed-off-by: default avatarGuenter Roeck <linux@roeck-us.net>
parent f9c0cf8f

drivers/hwmon/adm9240.c

+8 −2
Original line number Diff line number Diff line
@@ -501,17 +501,23 @@ static int adm9240_fan_read(struct device *dev, u32 attr, int channel, long *val 


	switch (attr) {

	case hwmon_fan_input:

		mutex_lock(&data->update_lock);

		err = regmap_read(data->regmap, ADM9240_REG_FAN(channel), &regval);

		if (err < 0)

		if (err < 0) {

			mutex_unlock(&data->update_lock);

			return err;

		}

		if (regval == 255 && data->fan_div[channel] < 3) {

			/* adjust fan clock divider on overflow */

			err = adm9240_write_fan_div(data, channel,

						    ++data->fan_div[channel]);

			if (err)

			if (err) {

				mutex_unlock(&data->update_lock);

				return err;

			}

		}

		*val = FAN_FROM_REG(regval, BIT(data->fan_div[channel]));

		mutex_unlock(&data->update_lock);

		break;

	case hwmon_fan_div:

		*val = BIT(data->fan_div[channel]);