Re: [PATCH v1 1/1] iio: Fix iio_multiply_value use in iio_read_channel_processed_scale

[Jonathan Cameron <jic23@kernel.org>]

On Thu, 16 Apr 2026 14:31:00 +0200
Hans de Goede <hansg@kernel.org> wrote:

> Hi,
> 
> On 16-Apr-26 13:14, Svyatoslav Ryhel wrote:
> > The function iio_multiply_value returns IIO_VAL_INT (1) on success or a
> > negative error number on failure, while iio_read_channel_processed_scale
> > should return an error code or 0. This creates a situation where the
> > expected result is treated as an error. Fix this by checking the
> > iio_multiply_value result separately, instead of passing it as a return
> > value.
> > 
> > Fixes: 05f958d003c9 ("iio: Improve iio_read_channel_processed_scale() precision")
> > Signed-off-by: Svyatoslav Ryhel <clamor95@gmail.com>  
> 
> Thank you, good catch:
Indeed and 'ouch'.

Anyhow, applied to the fixes-togreg branch of iio.git and marked
for stable.

Thanks,

Jonathan

> 
> Reviewed-by: Hans de Goede <johannes.goede@oss.qualcomm.com>
> 
> Regards,
> 
> Hans
> 
> 
> 
> > ---
> >  drivers/iio/inkern.c | 6 +++++-
> >  1 file changed, 5 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/iio/inkern.c b/drivers/iio/inkern.c
> > index 0df0ab3de270..9ce20cb05a9b 100644
> > --- a/drivers/iio/inkern.c
> > +++ b/drivers/iio/inkern.c
> > @@ -738,7 +738,11 @@ int iio_read_channel_processed_scale(struct iio_channel *chan, int *val,
> >  		if (ret < 0)
> >  			return ret;
> >  
> > -		return iio_multiply_value(val, scale, ret, pval, pval2);
> > +		ret = iio_multiply_value(val, scale, ret, pval, pval2);
> > +		if (ret < 0)
> > +			return ret;
> > +
> > +		return 0;
> >  	} else {
> >  		ret = iio_channel_read(chan, val, NULL, IIO_CHAN_INFO_RAW);
> >  		if (ret < 0)  
> 
>