On Mon, 28 Aug 2023 23:02:07 +0800
Zhang Shurong <zhang_shurong@xxxxxxxxxxx> wrote:
> 在 2023年7月17日星期一 CST 上午12:08:21，Jonathan Cameron 写道：
> > On Sat, 15 Jul 2023 23:55:50 +0800
> >
> > Zhang Shurong <zhang_shurong@xxxxxxxxxxx> wrote:
> > > of_match_device() may fail and returns a NULL pointer.
> > >
> > > Fix this by checking the return value of of_match_device().
> > >
> > > Fixes: 64ad7f6438f3 ("iio: adc: stm32: introduce compatible data cfg")
> > > Signed-off-by: Zhang Shurong <zhang_shurong@xxxxxxxxxxx>
> >
> > Hi Zhang,
> >
> > I'm not sure we can actually make this bug happen. Do you have
> > a way of triggering it? The driver is only probed on devices where
> > that match will work.
> >
> > Also, assuming the match table is the same one associated with this probe
> > function, then us priv->cfg = of_device_get_match_data() and check the
> > output of that which is what we really care about.
> >
> > Jonathan
> >
> > > ---
> > >
> > > drivers/iio/adc/stm32-adc-core.c | 9 +++++++--
> > > 1 file changed, 7 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/drivers/iio/adc/stm32-adc-core.c
> > > b/drivers/iio/adc/stm32-adc-core.c index 48f02dcc81c1..70011fdbf5f6
> > > 100644
> > > --- a/drivers/iio/adc/stm32-adc-core.c
> > > +++ b/drivers/iio/adc/stm32-adc-core.c
> > > @@ -706,6 +706,8 @@ static int stm32_adc_probe(struct platform_device
> > > *pdev)>
> > > struct stm32_adc_priv *priv;
> > > struct device *dev = &pdev->dev;
> > > struct device_node *np = pdev->dev.of_node;
> > >
> > > + const struct of_device_id *of_id;
> > > +
> > >
> > > struct resource *res;
> > > u32 max_rate;
> > > int ret;
> > >
> > > @@ -718,8 +720,11 @@ static int stm32_adc_probe(struct platform_device
> > > *pdev)>
> > > return -ENOMEM;
> > >
> > > platform_set_drvdata(pdev, &priv->common);
> > >
> > > - priv->cfg = (const struct stm32_adc_priv_cfg *)
> > > - of_match_device(dev->driver->of_match_table, dev)->data;
> > > + of_id = of_match_device(dev->driver->of_match_table, dev);
> > > + if (!of_id)
> > > + return -ENODEV;
> > > +
> > > + priv->cfg = (const struct stm32_adc_priv_cfg *)of_id->data;
> > >
> > > priv->nb_adc_max = priv->cfg->num_adcs;
> > > spin_lock_init(&priv->common.lock);
> Hello Jonathan,
>
> I think we can make it happen by designing the platform device in a way that
> its name aligns with that of the driver. In such a scenario, when the driver
> is probed, the of_match_device function will return null. You can verify this
> functionality by reviewing the following function:
>
> static int platform_match(struct device *dev, struct device_driver *drv)
I don't think we care about that case. If there is a real example of
why someone would do this then that would be a different matter.
Jonathan
>
> Best regards,
> Shurong
>
>
>
