2021-05-10 09:58:20

by Andy Shevchenko

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

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 <[email protected]>
Signed-off-by: Andy Shevchenko <[email protected]>
---
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

2021-05-12 19:38:08

by Alexandru Ardelean

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

On Mon, May 10, 2021 at 12:59 PM Andy Shevchenko
<[email protected]> 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 <[email protected]>

>
> Fixes: cbbb819837f6 ("iio: dac: ad5770r: Add AD5770R support")
> Cc: Alexandru Tachici <[email protected]>
> Signed-off-by: Andy Shevchenko <[email protected]>
> ---
> 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
>

2021-05-13 17:10:12

by Jonathan Cameron

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

On Thu, 13 May 2021 01:00:22 +0300
Andy Shevchenko <[email protected]> wrote:

> On Wednesday, May 12, 2021, Alexandru Ardelean <[email protected]>
> wrote:
>
> > On Mon, May 10, 2021 at 12:59 PM Andy Shevchenko
> > <[email protected]> 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 <[email protected]>
> >
> >
> 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 <[email protected]>
> > > Signed-off-by: Andy Shevchenko <[email protected]>
> > > ---
> > > 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
> > >
> >
>
>