Re: ADT746X: logical-bitwise & confusion in set_max_duty_at_crit()

Roel Kluin
2008-03-10T10:00:05Z

Segher Boessenkool wrote:
>> diff --git a/drivers/hwmon/adt7473.c b/drivers/hwmon/adt7473.c
>> index 9587869..8ea7da2 100644
>> --- a/drivers/hwmon/adt7473.c
>> +++ b/drivers/hwmon/adt7473.c
>> @@ -570,7 +570,7 @@ static ssize_t set_max_duty_at_crit(struct device
>> *dev,
>> struct i2c_client *client = to_i2c_client(dev);
>> struct adt7473_data *data = i2c_get_clientdata(client);
>> int temp = simple_strtol(buf, NULL, 10);
>> - temp = temp && 0xFF;
>> + temp &= 0xFF;
>>
>> mutex_lock(&data->lock);
>> data->max_duty_at_overheat = temp;
>
> The & 0xff here is bogus anyway; temp is only ever used as an u8,
> so just declare it as that, or do proper overflow/underflow checking
> on it. The patch will need testing on hardware too, since it changes
> behaviour (it should be a bugfix, but who knows).

Maybe someone can test this?
---
logical-bitwise & confusion

Signed-off-by: Roel Kluin <12o3l@tiscali.nl>
---
diff --git a/drivers/hwmon/adt7473.c b/drivers/hwmon/adt7473.c
index 9587869..2a2de73 100644
--- a/drivers/hwmon/adt7473.c
+++ b/drivers/hwmon/adt7473.c
@@ -566,11 +566,11 @@ static ssize_t set_max_duty_at_crit(struct device *dev,
const char *buf,
size_t count)
{
- u8 reg;
+ u8 reg, temp;
struct i2c_client *client = to_i2c_client(dev);
struct adt7473_data *data = i2c_get_clientdata(client);
- int temp = simple_strtol(buf, NULL, 10);
- temp = temp && 0xFF;
+
+ temp = simple_strtol(buf, NULL, 10) & 0xFF;