[PATCH] iio: adc: ad_sigma_delta.c: Cleaning up uninitialized variables

[PATCH] iio: adc: ad_sigma_delta.c: Cleaning up uninitialized variables

[Rickard Strandqvist]

There is a risk that the variable will be used without being initialized.

This was largely found by using a static code analysis program called cppcheck.

Signed-off-by: Rickard Strandqvist <rickard_strandqvist@spectrumdigital.se>
---
 drivers/iio/adc/ad_sigma_delta.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/iio/adc/ad_sigma_delta.c b/drivers/iio/adc/ad_sigma_delta.c
index 9a4e0e3..d58fad9 100644
--- a/drivers/iio/adc/ad_sigma_delta.c
+++ b/drivers/iio/adc/ad_sigma_delta.c
@@ -248,7 +248,7 @@ int ad_sigma_delta_single_conversion(struct iio_dev *indio_dev,
 	const struct iio_chan_spec *chan, int *val)
 {
 	struct ad_sigma_delta *sigma_delta = iio_device_get_drvdata(indio_dev);
-	unsigned int sample, raw_sample;
+	unsigned int sample, raw_sample = 0;
 	int ret = 0;
 
 	if (iio_buffer_enabled(indio_dev))
-- 
1.7.10.4

Re: [PATCH] iio: adc: ad_sigma_delta.c: Cleaning up uninitialized variables

[Lars-Peter Clausen]

On 06/01/2014 01:11 AM, Rickard Strandqvist wrote:
> There is a risk that the variable will be used without being initialized.
>
> This was largely found by using a static code analysis program called cppcheck.

This looks like a false positive. And if it was not a false positive the 
correct fix certainly is not to initialize the variable to some random value 
to silence the warning.

- Lars

Re: [PATCH] iio: adc: ad_sigma_delta.c: Cleaning up uninitialized variables

[Rickard Strandqvist]

Hi

Believe it reacted to the code below.

If raw_sample = 0 is the correct starting value, I am not sure. But
leaving it uninitialized, I think is the worst choice.


    if (ret < 0)
        goto out;

    ret = ad_sd_read_reg(sigma_delta, AD_SD_REG_DATA,
        DIV_ROUND_UP(chan->scan_type.realbits + chan->scan_type.shift, 8),
        &raw_sample);
....
out:
....
    sample = raw_sample >> chan->scan_type.shift;


Best regards
Rickard Strandqvist


2014-06-01 11:15 GMT+02:00 Lars-Peter Clausen <lars@metafoo.de>:
> On 06/01/2014 01:11 AM, Rickard Strandqvist wrote:
>>
>> There is a risk that the variable will be used without being initialized.
>>
>> This was largely found by using a static code analysis program called
>> cppcheck.
>
>
> This looks like a false positive. And if it was not a false positive the
> correct fix certainly is not to initialize the variable to some random value
> to silence the warning.
>
> - Lars
>

Re: [PATCH] iio: adc: ad_sigma_delta.c: Cleaning up uninitialized variables

[Lars-Peter Clausen]

On 06/01/2014 01:51 PM, Rickard Strandqvist wrote:
> Hi
>
> Believe it reacted to the code below.
>
> If raw_sample = 0 is the correct starting value, I am not sure. But
> leaving it uninitialized, I think is the worst choice.
>
>
>      if (ret < 0)
>          goto out;
>
>      ret = ad_sd_read_reg(sigma_delta, AD_SD_REG_DATA,
>          DIV_ROUND_UP(chan->scan_type.realbits + chan->scan_type.shift, 8),
>          &raw_sample);
> ....
> out:
> ....

you skipped the:

     if (ret)
         return ret;

that is here.

>      sample = raw_sample >> chan->scan_type.shift;
>

The code is a bit confusing and it is understandable that a static checker 
might generate a false positive. The fix though is not to silence the false 
positive as this will hide actual problems if they should come up by future 
modifications of the code.

>
> Best regards
> Rickard Strandqvist
>
>
> 2014-06-01 11:15 GMT+02:00 Lars-Peter Clausen <lars@metafoo.de>:
>> On 06/01/2014 01:11 AM, Rickard Strandqvist wrote:
>>>
>>> There is a risk that the variable will be used without being initialized.
>>>
>>> This was largely found by using a static code analysis program called
>>> cppcheck.
>>
>>
>> This looks like a false positive. And if it was not a false positive the
>> correct fix certainly is not to initialize the variable to some random value
>> to silence the warning.
>>
>> - Lars
>>

Re: [PATCH] iio: adc: ad_sigma_delta.c: Cleaning up uninitialized variables

[Rickard Strandqvist]

Aaa, that is true!  Sorry my mistake :(


Best regards
Rickard Strandqvist


2014-06-01 14:03 GMT+02:00 Lars-Peter Clausen <lars@metafoo.de>:
> On 06/01/2014 01:51 PM, Rickard Strandqvist wrote:
>>
>> Hi
>>
>> Believe it reacted to the code below.
>>
>> If raw_sample = 0 is the correct starting value, I am not sure. But
>> leaving it uninitialized, I think is the worst choice.
>>
>>
>>      if (ret < 0)
>>          goto out;
>>
>>      ret = ad_sd_read_reg(sigma_delta, AD_SD_REG_DATA,
>>          DIV_ROUND_UP(chan->scan_type.realbits + chan->scan_type.shift,
>> 8),
>>          &raw_sample);
>> ....
>> out:
>> ....
>
>
> you skipped the:
>
>     if (ret)
>         return ret;
>
> that is here.
>
>
>>      sample = raw_sample >> chan->scan_type.shift;
>>
>
> The code is a bit confusing and it is understandable that a static checker
> might generate a false positive. The fix though is not to silence the false
> positive as this will hide actual problems if they should come up by future
> modifications of the code.
>
>
>>
>> Best regards
>> Rickard Strandqvist
>>
>>
>> 2014-06-01 11:15 GMT+02:00 Lars-Peter Clausen <lars@metafoo.de>:
>>>
>>> On 06/01/2014 01:11 AM, Rickard Strandqvist wrote:
>>>>
>>>>
>>>> There is a risk that the variable will be used without being
>>>> initialized.
>>>>
>>>> This was largely found by using a static code analysis program called
>>>> cppcheck.
>>>
>>>
>>>
>>> This looks like a false positive. And if it was not a false positive the
>>> correct fix certainly is not to initialize the variable to some random
>>> value
>>> to silence the warning.
>>>
>>> - Lars
>>>
>