On 06/24/2016 09:47 PM, Guenter Roeck wrote:
> The result of an integer divide by an unsigned is undefined.
> This causes unexpected results when writing negative values
> into the limit registers.
>
> Maintain the shunt_resistors variables as signed integer to avoid
> the problem. Also, for simplicity and ease of use, clamp shunt
> resistor value on writes instead of rejecting bad values.
>
> Cc: Andrew F. Davis <afd@xxxxxx>
> Signed-off-by: Guenter Roeck <linux@xxxxxxxxxxxx>
> ---
Acked-by: Andrew F. Davis <afd@xxxxxx>
> drivers/hwmon/ina3221.c | 13 ++++++-------
> 1 file changed, 6 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/hwmon/ina3221.c b/drivers/hwmon/ina3221.c
> index d055b6a2266b..e6b49500c52a 100644
> --- a/drivers/hwmon/ina3221.c
> +++ b/drivers/hwmon/ina3221.c
> @@ -95,7 +95,7 @@ static const unsigned int register_channel[] = {
> struct ina3221_data {
> struct regmap *regmap;
> struct regmap_field *fields[F_MAX_FIELDS];
> - unsigned int shunt_resistors[INA3221_NUM_CHANNELS];
> + int shunt_resistors[INA3221_NUM_CHANNELS];
> };
>
> static int ina3221_read_value(struct ina3221_data *ina, unsigned int reg,
> @@ -155,7 +155,7 @@ static ssize_t ina3221_show_current(struct device *dev,
> struct ina3221_data *ina = dev_get_drvdata(dev);
> unsigned int reg = sd_attr->index;
> unsigned int channel = register_channel[reg];
> - unsigned int resistance_uo = ina->shunt_resistors[channel];
> + int resistance_uo = ina->shunt_resistors[channel];
> int val, current_ma, voltage_nv, ret;
>
> ret = ina3221_read_value(ina, reg, &val);
> @@ -176,7 +176,7 @@ static ssize_t ina3221_set_current(struct device *dev,
> struct ina3221_data *ina = dev_get_drvdata(dev);
> unsigned int reg = sd_attr->index;
> unsigned int channel = register_channel[reg];
> - unsigned int resistance_uo = ina->shunt_resistors[channel];
> + int resistance_uo = ina->shunt_resistors[channel];
> int val, current_ma, voltage_uv, ret;
>
> ret = kstrtoint(buf, 0, ¤t_ma);
> @@ -223,15 +223,14 @@ static ssize_t ina3221_set_shunt(struct device *dev,
> struct sensor_device_attribute *sd_attr = to_sensor_dev_attr(attr);
> struct ina3221_data *ina = dev_get_drvdata(dev);
> unsigned int channel = sd_attr->index;
> - unsigned int val;
> + int val;
> int ret;
>
> - ret = kstrtouint(buf, 0, &val);
> + ret = kstrtoint(buf, 0, &val);
> if (ret)
> return ret;
>
> - if (val == 0)
> - return -EINVAL;
> + val = clamp_val(val, 1, INT_MAX);
>
> ina->shunt_resistors[channel] = val;
>
>
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