[PATCH v1 1/1] iio: dac: ad5770r: Put fwnode in error case during ->probe()

[PATCH v1 1/1] iio: dac: ad5770r: Put fwnode in error case during ->probe()

[Andy Shevchenko]

device_for_each_child_node() bumps a reference counting of a returned variable.
We have to balance it whenever we return to the caller.

Fixes: cbbb819837f6 ("iio: dac: ad5770r: Add AD5770R support")
Cc: Alexandru Tachici <alexandru.tachici@analog.com>
Signed-off-by: Andy Shevchenko <andy.shevchenko@gmail.com>
---
 drivers/iio/dac/ad5770r.c | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/drivers/iio/dac/ad5770r.c b/drivers/iio/dac/ad5770r.c
index 7ab2ccf90863..8107f7bbbe3c 100644
--- a/drivers/iio/dac/ad5770r.c
+++ b/drivers/iio/dac/ad5770r.c
@@ -524,23 +524,29 @@ static int ad5770r_channel_config(struct ad5770r_state *st)
 	device_for_each_child_node(&st->spi->dev, child) {
 		ret = fwnode_property_read_u32(child, "num", &num);
 		if (ret)
-			return ret;
-		if (num >= AD5770R_MAX_CHANNELS)
-			return -EINVAL;
+			goto err_child_out;
+		if (num >= AD5770R_MAX_CHANNELS) {
+			ret = -EINVAL;
+			goto err_child_out;
+		}
 
 		ret = fwnode_property_read_u32_array(child,
 						     "adi,range-microamp",
 						     tmp, 2);
 		if (ret)
-			return ret;
+			goto err_child_out;
 
 		min = tmp[0] / 1000;
 		max = tmp[1] / 1000;
 		ret = ad5770r_store_output_range(st, min, max, num);
 		if (ret)
-			return ret;
+			goto err_child_out;
 	}
 
+	return 0;
+
+err_child_out:
+	fwnode_handle_put(child);
 	return ret;
 }
 
-- 
2.31.1

Re: [PATCH v1 1/1] iio: dac: ad5770r: Put fwnode in error case during ->probe()

[Alexandru Ardelean]

On Mon, May 10, 2021 at 12:59 PM Andy Shevchenko
<andy.shevchenko@gmail.com> wrote:
>
> device_for_each_child_node() bumps a reference counting of a returned variable.
> We have to balance it whenever we return to the caller.

This feels like the device_for_each_child_node() [and the of_node
variant] iterator[s] need[s] some re-design to account for how easy it
is to slip stuff by.
But that's something quite out of this scope.

Reviewed-by: Alexandru Ardelean <ardeleanalex@gmail.com>

>
> Fixes: cbbb819837f6 ("iio: dac: ad5770r: Add AD5770R support")
> Cc: Alexandru Tachici <alexandru.tachici@analog.com>
> Signed-off-by: Andy Shevchenko <andy.shevchenko@gmail.com>
> ---
>  drivers/iio/dac/ad5770r.c | 16 +++++++++++-----
>  1 file changed, 11 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/iio/dac/ad5770r.c b/drivers/iio/dac/ad5770r.c
> index 7ab2ccf90863..8107f7bbbe3c 100644
> --- a/drivers/iio/dac/ad5770r.c
> +++ b/drivers/iio/dac/ad5770r.c
> @@ -524,23 +524,29 @@ static int ad5770r_channel_config(struct ad5770r_state *st)
>         device_for_each_child_node(&st->spi->dev, child) {
>                 ret = fwnode_property_read_u32(child, "num", &num);
>                 if (ret)
> -                       return ret;
> -               if (num >= AD5770R_MAX_CHANNELS)
> -                       return -EINVAL;
> +                       goto err_child_out;
> +               if (num >= AD5770R_MAX_CHANNELS) {
> +                       ret = -EINVAL;
> +                       goto err_child_out;
> +               }
>
>                 ret = fwnode_property_read_u32_array(child,
>                                                      "adi,range-microamp",
>                                                      tmp, 2);
>                 if (ret)
> -                       return ret;
> +                       goto err_child_out;
>
>                 min = tmp[0] / 1000;
>                 max = tmp[1] / 1000;
>                 ret = ad5770r_store_output_range(st, min, max, num);
>                 if (ret)
> -                       return ret;
> +                       goto err_child_out;
>         }
>
> +       return 0;
> +
> +err_child_out:
> +       fwnode_handle_put(child);
>         return ret;
>  }
>
> --
> 2.31.1
>

Re: [PATCH v1 1/1] iio: dac: ad5770r: Put fwnode in error case during ->probe()

[Jonathan Cameron]

On Thu, 13 May 2021 01:00:22 +0300
Andy Shevchenko <andy.shevchenko@gmail.com> wrote:

> On Wednesday, May 12, 2021, Alexandru Ardelean <ardeleanalex@gmail.com>
> wrote:
> 
> > On Mon, May 10, 2021 at 12:59 PM Andy Shevchenko
> > <andy.shevchenko@gmail.com> wrote:  
> > >
> > > device_for_each_child_node() bumps a reference counting of a returned  
> > variable.  
> > > We have to balance it whenever we return to the caller.  
> >
> > This feels like the device_for_each_child_node() [and the of_node
> > variant] iterator[s] need[s] some re-design to account for how easy it
> > is to slip stuff by.  
> 
> 
> I don’t know how you can do it differently if you wish to give a guarantee
> that object doesn’t suddenly disappear while you are iterating over it.
> 
> Look at the bus_find_device() and similar APIs, they basically do the
> similar.
> 
> 
> 
> > But that's something quite out of this scope.
> >
> > Reviewed-by: Alexandru Ardelean <ardeleanalex@gmail.com>
> >
> >  
> Thanks.
> 
Applied to the fixes-togreg branch of iio.git and marked for stable.

Thanks,

Joathan

> 
> > >
> > > Fixes: cbbb819837f6 ("iio: dac: ad5770r: Add AD5770R support")
> > > Cc: Alexandru Tachici <alexandru.tachici@analog.com>
> > > Signed-off-by: Andy Shevchenko <andy.shevchenko@gmail.com>
> > > ---
> > >  drivers/iio/dac/ad5770r.c | 16 +++++++++++-----
> > >  1 file changed, 11 insertions(+), 5 deletions(-)
> > >
> > > diff --git a/drivers/iio/dac/ad5770r.c b/drivers/iio/dac/ad5770r.c
> > > index 7ab2ccf90863..8107f7bbbe3c 100644
> > > --- a/drivers/iio/dac/ad5770r.c
> > > +++ b/drivers/iio/dac/ad5770r.c
> > > @@ -524,23 +524,29 @@ static int ad5770r_channel_config(struct  
> > ad5770r_state *st)  
> > >         device_for_each_child_node(&st->spi->dev, child) {
> > >                 ret = fwnode_property_read_u32(child, "num", &num);
> > >                 if (ret)
> > > -                       return ret;
> > > -               if (num >= AD5770R_MAX_CHANNELS)
> > > -                       return -EINVAL;
> > > +                       goto err_child_out;
> > > +               if (num >= AD5770R_MAX_CHANNELS) {
> > > +                       ret = -EINVAL;
> > > +                       goto err_child_out;
> > > +               }
> > >
> > >                 ret = fwnode_property_read_u32_array(child,
> > >  
> > "adi,range-microamp",  
> > >                                                      tmp, 2);
> > >                 if (ret)
> > > -                       return ret;
> > > +                       goto err_child_out;
> > >
> > >                 min = tmp[0] / 1000;
> > >                 max = tmp[1] / 1000;
> > >                 ret = ad5770r_store_output_range(st, min, max, num);
> > >                 if (ret)
> > > -                       return ret;
> > > +                       goto err_child_out;
> > >         }
> > >
> > > +       return 0;
> > > +
> > > +err_child_out:
> > > +       fwnode_handle_put(child);
> > >         return ret;
> > >  }
> > >
> > > --
> > > 2.31.1
> > >  
> >  
> 
>