[PATCH v2] hwmon: (lm80) fix a missing check of the status of SMBus read

[Kangjie Lu]

If lm80_read_value() fails, it returns a negative number instead of the
correct read data. Therefore, we should avoid using the data if it
fails.

The fix checks if lm80_read_value() fails, and if so, returns with the
error number.

Signed-off-by: Kangjie Lu <k...@umn.edu>
---
 drivers/hwmon/lm80.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/hwmon/lm80.c b/drivers/hwmon/lm80.c
index 08e3945a6fbf..d91333557f04 100644
--- a/drivers/hwmon/lm80.c
+++ b/drivers/hwmon/lm80.c
@@ -360,6 +360,7 @@ static ssize_t set_fan_div(struct device *dev, struct 
device_attribute *attr,
        struct i2c_client *client = data->client;
        unsigned long min, val;
        u8 reg;
+       int rv;
        int err = kstrtoul(buf, 10, &val);
        if (err < 0)
                return err;
@@ -390,8 +391,11 @@ static ssize_t set_fan_div(struct device *dev, struct 
device_attribute *attr,
                return -EINVAL;
        }
 
-       reg = (lm80_read_value(client, LM80_REG_FANDIV) &
-              ~(3 << (2 * (nr + 1)))) | (data->fan_div[nr] << (2 * (nr + 1)));
+       rv = lm80_read_value(client, LM80_REG_FANDIV);
+       if (rv < 0)
+               return rv;
+       reg = (rv & ~(3 << (2 * (nr + 1))))
+           | (data->fan_div[nr] << (2 * (nr + 1)));
        lm80_write_value(client, LM80_REG_FANDIV, reg);
 
        /* Restore fan_min */
-- 
2.17.1