On Sat, 24 Jul 2021 16:48:40 +0100
Jonathan Cameron <jic23@xxxxxxxxxx> wrote:
> On Mon, 19 Jul 2021 19:53:11 +0000
> Yizhuo <yzhai003@xxxxxxx> wrote:
>
> > Inside function stm32_dfsdm_irq(), the variable "status", "int_en"
> > could be uninitialized if the regmap_read() fails and returns an error
> > code. However, they are directly used in the later context to decide
> > the control flow, which is potentially unsafe.
> >
> > Fixes: e2e6771c64625 ("IIO: ADC: add STM32 DFSDM sigma delta ADC support")
> >
> > Signed-off-by: Yizhuo <yzhai003@xxxxxxx>
>
> Hi Yizhou
>
> I want to get some review of this from people familiar with the
> hardware as there is a small possibility your reordering might have
> introduced a problem.
To stm32 people, can someone take a look at this?
Thanks,
Jonathan
>
> > ---
> > drivers/iio/adc/stm32-dfsdm-adc.c | 9 +++++++--
> > 1 file changed, 7 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/iio/adc/stm32-dfsdm-adc.c b/drivers/iio/adc/stm32-dfsdm-adc.c
> > index 1cfefb3b5e56..d8b78aead942 100644
> > --- a/drivers/iio/adc/stm32-dfsdm-adc.c
> > +++ b/drivers/iio/adc/stm32-dfsdm-adc.c
> > @@ -1292,9 +1292,11 @@ static irqreturn_t stm32_dfsdm_irq(int irq, void *arg)
> > struct stm32_dfsdm_adc *adc = iio_priv(indio_dev);
> > struct regmap *regmap = adc->dfsdm->regmap;
> > unsigned int status, int_en;
> > + int ret;
> >
> > - regmap_read(regmap, DFSDM_ISR(adc->fl_id), &status);
> > - regmap_read(regmap, DFSDM_CR2(adc->fl_id), &int_en);
>
> Moving this later is only valid if there aren't any side effects.
> The current ordering is strange enough it makes me wonder if there might be!
>
> Jonathan
>
> > + ret = regmap_read(regmap, DFSDM_ISR(adc->fl_id), &status);
> > + if (ret)
> > + return IRQ_HANDLED;
> >
> > if (status & DFSDM_ISR_REOCF_MASK) {
> > /* Read the data register clean the IRQ status */
> > @@ -1303,6 +1305,9 @@ static irqreturn_t stm32_dfsdm_irq(int irq, void *arg)
> > }
> >
> > if (status & DFSDM_ISR_ROVRF_MASK) {
> > + ret = regmap_read(regmap, DFSDM_CR2(adc->fl_id), &int_en);
> > + if (ret)
> > + return IRQ_HANDLED;
> > if (int_en & DFSDM_CR2_ROVRIE_MASK)
> > dev_warn(&indio_dev->dev, "Overrun detected\n");
> > regmap_update_bits(regmap, DFSDM_ICR(adc->fl_id),
>
