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

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Date:   Wed, 12 May 2021 20:33:09 +0300
From:   Alexandru Ardelean <ardeleanalex@...il.com>
To:     Andy Shevchenko <andy.shevchenko@...il.com>
Cc:     Jonathan Cameron <Jonathan.Cameron@...wei.com>,
        linux-iio <linux-iio@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Michael Hennerich <Michael.Hennerich@...log.com>,
        Jonathan Cameron <jic23@...nel.org>,
        Alexandru Tachici <alexandru.tachici@...log.com>
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
<andy.shevchenko@...il.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@...il.com>

>
> Fixes: cbbb819837f6 ("iio: dac: ad5770r: Add AD5770R support")
> Cc: Alexandru Tachici <alexandru.tachici@...log.com>
> Signed-off-by: Andy Shevchenko <andy.shevchenko@...il.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
>