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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: Li Zhong <floridsleeves@gmail.com>
Link: https://lore.kernel.org/r/20220924001751.1726369-1-floridsleeves@gmail.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
This commit is contained in:
Li Zhong 2022-09-23 17:17:51 -07:00 committed by Guenter Roeck
parent f9c0cf8f26
commit 8887516f01
1 changed files with 8 additions and 2 deletions
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10
drivers/hwmon/adm9240.c
View File

@ -501,17 +501,23 @@ static int adm9240_fan_read(struct device *dev, u32 attr, int channel, long *val
switch (attr) { switch (attr) {
case hwmon_fan_input: case hwmon_fan_input:
mutex_lock(&data->update_lock);
err = regmap_read(data->regmap, ADM9240_REG_FAN(channel), &regval); err = regmap_read(data->regmap, ADM9240_REG_FAN(channel), &regval);
if (err < 0) if (err < 0) {
mutex_unlock(&data->update_lock);
return err; return err;
}
if (regval == 255 && data->fan_div[channel] < 3) { if (regval == 255 && data->fan_div[channel] < 3) {
/* adjust fan clock divider on overflow */ /* adjust fan clock divider on overflow */
err = adm9240_write_fan_div(data, channel, err = adm9240_write_fan_div(data, channel,
++data->fan_div[channel]); ++data->fan_div[channel]);
if (err) if (err) {
mutex_unlock(&data->update_lock);
return err; return err;
} }
}
*val = FAN_FROM_REG(regval, BIT(data->fan_div[channel])); *val = FAN_FROM_REG(regval, BIT(data->fan_div[channel]));
mutex_unlock(&data->update_lock);
break; break;
case hwmon_fan_div: case hwmon_fan_div:
*val = BIT(data->fan_div[channel]); *val = BIT(data->fan_div[channel]);