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* [lm-sensors] [PATCH v3] hwmon: (lm92) Prevent overflow problem when writing large limits
@ 2014-08-05  2:08 Axel Lin
  2014-08-05  2:40 ` Guenter Roeck
  2014-08-05  2:43 ` Axel Lin
  0 siblings, 2 replies; 3+ messages in thread
From: Axel Lin @ 2014-08-05  2:08 UTC (permalink / raw)
  To: lm-sensors

On platforms with sizeof(int) < sizeof(long), writing a temperature
limit larger than MAXINT will result in unpredictable limit values
written to the chip. Avoid auto-conversion from long to int to fix
the problem.

The hysteresis temperature range depends on the value of
data->temp[attr->index], since val is subtracted from it.
Use a wider clamp, [-120000, 220000] should do to cover the
possible range.

Also uses clamp_val to simplify the code a bit.

Signed-off-by: Axel Lin <axel.lin@ingics.com>
---
 drivers/hwmon/lm92.c | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/drivers/hwmon/lm92.c b/drivers/hwmon/lm92.c
index d2060e2..08a261d 100644
--- a/drivers/hwmon/lm92.c
+++ b/drivers/hwmon/lm92.c
@@ -74,12 +74,9 @@ static inline int TEMP_FROM_REG(s16 reg)
 	return reg / 8 * 625 / 10;
 }
 
-static inline s16 TEMP_TO_REG(int val)
+static inline s16 TEMP_TO_REG(long val)
 {
-	if (val <= -60000)
-		return -60000 * 10 / 625 * 8;
-	if (val >= 160000)
-		return 160000 * 10 / 625 * 8;
+	val = clamp_val(val, -60000, 160000);
 	return val * 10 / 625 * 8;
 }
 
@@ -206,8 +203,10 @@ static ssize_t set_temp_hyst(struct device *dev,
 	if (err)
 		return err;
 
+	val = clamp_val(val, -120000, 220000);
 	mutex_lock(&data->update_lock);
-	data->temp[t_hyst] = TEMP_FROM_REG(data->temp[attr->index]) - val;
+	 data->temp[t_hyst] +		TEMP_TO_REG(TEMP_FROM_REG(data->temp[attr->index]) - val);
 	i2c_smbus_write_word_swapped(client, LM92_REG_TEMP_HYST,
 				     TEMP_TO_REG(data->temp[t_hyst]));
 	mutex_unlock(&data->update_lock);
-- 
1.9.1




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^ permalink raw reply related	[flat|nested] 3+ messages in thread
* Re: [lm-sensors] [PATCH v3] hwmon: (lm92) Prevent overflow problem when writing large limits
  2014-08-05  2:08 [lm-sensors] [PATCH v3] hwmon: (lm92) Prevent overflow problem when writing large limits Axel Lin
@ 2014-08-05  2:40 ` Guenter Roeck
  2014-08-05  2:43 ` Axel Lin
  1 sibling, 0 replies; 3+ messages in thread
From: Guenter Roeck @ 2014-08-05  2:40 UTC (permalink / raw)
  To: lm-sensors

On Tue, Aug 05, 2014 at 10:08:31AM +0800, Axel Lin wrote:
> On platforms with sizeof(int) < sizeof(long), writing a temperature
> limit larger than MAXINT will result in unpredictable limit values
> written to the chip. Avoid auto-conversion from long to int to fix
> the problem.
> 
> The hysteresis temperature range depends on the value of
> data->temp[attr->index], since val is subtracted from it.
> Use a wider clamp, [-120000, 220000] should do to cover the
> possible range.
> 
> Also uses clamp_val to simplify the code a bit.
> 
> Signed-off-by: Axel Lin <axel.lin@ingics.com>
> ---
>  drivers/hwmon/lm92.c | 11 +++++------
>  1 file changed, 5 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/hwmon/lm92.c b/drivers/hwmon/lm92.c
> index d2060e2..08a261d 100644
> --- a/drivers/hwmon/lm92.c
> +++ b/drivers/hwmon/lm92.c
> @@ -74,12 +74,9 @@ static inline int TEMP_FROM_REG(s16 reg)
>  	return reg / 8 * 625 / 10;
>  }
>  
> -static inline s16 TEMP_TO_REG(int val)
> +static inline s16 TEMP_TO_REG(long val)
>  {
> -	if (val <= -60000)
> -		return -60000 * 10 / 625 * 8;
> -	if (val >= 160000)
> -		return 160000 * 10 / 625 * 8;
> +	val = clamp_val(val, -60000, 160000);
>  	return val * 10 / 625 * 8;
>  }
>  
> @@ -206,8 +203,10 @@ static ssize_t set_temp_hyst(struct device *dev,
>  	if (err)
>  		return err;
>  
> +	val = clamp_val(val, -120000, 220000);
>  	mutex_lock(&data->update_lock);
> -	data->temp[t_hyst] = TEMP_FROM_REG(data->temp[attr->index]) - val;
> +	 data->temp[t_hyst] > +		TEMP_TO_REG(TEMP_FROM_REG(data->temp[attr->index]) - val);
>  	i2c_smbus_write_word_swapped(client, LM92_REG_TEMP_HYST,
>  				     TEMP_TO_REG(data->temp[t_hyst]));

Hi Axel,

Almost ... unfortunately, now you've got TEMP_TO_REG() on data->temp[t_hyst]
twice. No need to resend, I fixed it up myself.

Thanks,
Guenter

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^ permalink raw reply	[flat|nested] 3+ messages in thread
* Re: [lm-sensors] [PATCH v3] hwmon: (lm92) Prevent overflow problem when writing large limits
  2014-08-05  2:08 [lm-sensors] [PATCH v3] hwmon: (lm92) Prevent overflow problem when writing large limits Axel Lin
  2014-08-05  2:40 ` Guenter Roeck
@ 2014-08-05  2:43 ` Axel Lin
  1 sibling, 0 replies; 3+ messages in thread
From: Axel Lin @ 2014-08-05  2:43 UTC (permalink / raw)
  To: lm-sensors

2014-08-05 10:40 GMT+08:00 Guenter Roeck <linux@roeck-us.net>:
> On Tue, Aug 05, 2014 at 10:08:31AM +0800, Axel Lin wrote:
>> On platforms with sizeof(int) < sizeof(long), writing a temperature
>> limit larger than MAXINT will result in unpredictable limit values
>> written to the chip. Avoid auto-conversion from long to int to fix
>> the problem.
>>
>> The hysteresis temperature range depends on the value of
>> data->temp[attr->index], since val is subtracted from it.
>> Use a wider clamp, [-120000, 220000] should do to cover the
>> possible range.
>>
>> Also uses clamp_val to simplify the code a bit.
>>
>> Signed-off-by: Axel Lin <axel.lin@ingics.com>
>> ---
>>  drivers/hwmon/lm92.c | 11 +++++------
>>  1 file changed, 5 insertions(+), 6 deletions(-)
>>
>> diff --git a/drivers/hwmon/lm92.c b/drivers/hwmon/lm92.c
>> index d2060e2..08a261d 100644
>> --- a/drivers/hwmon/lm92.c
>> +++ b/drivers/hwmon/lm92.c
>> @@ -74,12 +74,9 @@ static inline int TEMP_FROM_REG(s16 reg)
>>       return reg / 8 * 625 / 10;
>>  }
>>
>> -static inline s16 TEMP_TO_REG(int val)
>> +static inline s16 TEMP_TO_REG(long val)
>>  {
>> -     if (val <= -60000)
>> -             return -60000 * 10 / 625 * 8;
>> -     if (val >= 160000)
>> -             return 160000 * 10 / 625 * 8;
>> +     val = clamp_val(val, -60000, 160000);
>>       return val * 10 / 625 * 8;
>>  }
>>
>> @@ -206,8 +203,10 @@ static ssize_t set_temp_hyst(struct device *dev,
>>       if (err)
>>               return err;
>>
>> +     val = clamp_val(val, -120000, 220000);
>>       mutex_lock(&data->update_lock);
>> -     data->temp[t_hyst] = TEMP_FROM_REG(data->temp[attr->index]) - val;
>> +      data->temp[t_hyst] >> +             TEMP_TO_REG(TEMP_FROM_REG(data->temp[attr->index]) - val);
>>       i2c_smbus_write_word_swapped(client, LM92_REG_TEMP_HYST,
>>                                    TEMP_TO_REG(data->temp[t_hyst]));
>
> Hi Axel,
>
> Almost ... unfortunately, now you've got TEMP_TO_REG() on data->temp[t_hyst]
> twice. No need to resend, I fixed it up myself.
Ah, thanks.

Axel

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lm-sensors@lm-sensors.org
http://lists.lm-sensors.org/mailman/listinfo/lm-sensors

^ permalink raw reply	[flat|nested] 3+ messages in thread
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2014-08-05  2:08 [lm-sensors] [PATCH v3] hwmon: (lm92) Prevent overflow problem when writing large limits Axel Lin
2014-08-05  2:40 ` Guenter Roeck
2014-08-05  2:43 ` Axel Lin

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