[Linux-stm32] [PATCH v3] iio: adc: stmpe-adc: Fix wait_for_completion_timeout return value check

[Jonathan Cameron]

On Tue, 12 Apr 2022 08:52:13 +0000
Philippe Schenker <philippe.schenker at toradex.com> wrote:

> On Tue, 2022-04-12 at 06:51 +0000, Miaoqian Lin wrote:
> > wait_for_completion_timeout() returns unsigned long not long.
> > it returns 0 if timed out, and positive if completed.
> > The check for <= 0 is ambiguous and should be == 0 here
> > indicating timeout which is the only error case
> > 
> > Fixes: e813dde6f833 ("iio: stmpe-adc: Use
> > wait_for_completion_timeout")
> > Signed-off-by: Miaoqian Lin <linmq006 at gmail.com>  
> 
> Reviewed-by: Philippe Schenker <philippe.schenker at toradex.com>
Applied to the togreg branch of iio.git and pushed out as testing
to see if 0-day can find any problems we missed.

I'm not pushing this back to stable however because the
current code isn't strictly speaking buggy it's just odd
/ misleading.

Jonathan

> 
> > ---
> > changes in v2:
> > - Fix same issue in stmpe_read_temp.
> > ---
> > changes in v3:
> > - update the patch subject.
> > ---
> >  drivers/iio/adc/stmpe-adc.c | 8 ++++----
> >  1 file changed, 4 insertions(+), 4 deletions(-)
> > 
> > diff --git a/drivers/iio/adc/stmpe-adc.c b/drivers/iio/adc/stmpe-adc.c
> > index d2d405388499..83e0ac4467ca 100644
> > --- a/drivers/iio/adc/stmpe-adc.c
> > +++ b/drivers/iio/adc/stmpe-adc.c
> > @@ -61,7 +61,7 @@ struct stmpe_adc {
> >  static int stmpe_read_voltage(struct stmpe_adc *info,
> >                 struct iio_chan_spec const *chan, int *val)
> >  {
> > -       long ret;
> > +       unsigned long ret;
> >  
> >         mutex_lock(&info->lock);
> >  
> > @@ -79,7 +79,7 @@ static int stmpe_read_voltage(struct stmpe_adc
> > *info,
> >  
> >         ret = wait_for_completion_timeout(&info->completion,
> > STMPE_ADC_TIMEOUT);
> >  
> > -       if (ret <= 0) {
> > +       if (ret == 0) {
> >                 stmpe_reg_write(info->stmpe, STMPE_REG_ADC_INT_STA,
> >                                 STMPE_ADC_CH(info->channel));
> >                 mutex_unlock(&info->lock);
> > @@ -96,7 +96,7 @@ static int stmpe_read_voltage(struct stmpe_adc
> > *info,
> >  static int stmpe_read_temp(struct stmpe_adc *info,
> >                 struct iio_chan_spec const *chan, int *val)
> >  {
> > -       long ret;
> > +       unsigned long ret;
> >  
> >         mutex_lock(&info->lock);
> >  
> > @@ -114,7 +114,7 @@ static int stmpe_read_temp(struct stmpe_adc *info,
> >  
> >         ret = wait_for_completion_timeout(&info->completion,
> > STMPE_ADC_TIMEOUT);
> >  
> > -       if (ret <= 0) {
> > +       if (ret == 0) {
> >                 mutex_unlock(&info->lock);
> >                 return -ETIMEDOUT;
> >         }  
>