Re: [PATCH 12/13] iio: dac: ltc2688: Use __free(fwnode_handle) to replace fwnode_handle_put() calls

Nuno Sá
2024-01-15T10:23:15Z

On Sun, 2024-01-14 at 17:20 +0000, Jonathan Cameron wrote:
> From: Jonathan Cameron <Jonathan.Cameron@huawei.com>
>
> This use of the new cleanup.h scope based freeing infrastructure allows
> us to exit directly from error conditions within the
> device_for_each_child_node(dev, child) loop. On normal exit from that
> loop no fwnode_handle reference will be held and the child pointer
> will be NULL thus making the automatically run fwnode_handle_put() a
> noop.
>
> Cc: Nuno Sá <nuno.sa@analog.com>
> Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
> ---

Just one minor comment on my side. With that:

Reviewed-by: Nuno Sa <nuno.sa@analog.com>

I might be able to give this a quick test. Let's see if I can find the time for
it :)

>  drivers/iio/dac/ltc2688.c | 23 ++++++-----------------
>  1 file changed, 6 insertions(+), 17 deletions(-)
>
> diff --git a/drivers/iio/dac/ltc2688.c b/drivers/iio/dac/ltc2688.c
> index fc8eb53c65be..e8add3636af9 100644
> --- a/drivers/iio/dac/ltc2688.c
> +++ b/drivers/iio/dac/ltc2688.c
> @@ -746,7 +746,7 @@ static int ltc2688_span_lookup(const struct ltc2688_state
> *st, int min, int max)
>  static int ltc2688_channel_config(struct ltc2688_state *st)
>  {
>   struct device *dev = &st->spi->dev;
> - struct fwnode_handle *child;
> + struct fwnode_handle *child __free(fwnode_handle) = NULL;
>   u32 reg, clk_input, val, tmp[2];
>   int ret, span;
>
> @@ -754,18 +754,14 @@ static int ltc2688_channel_config(struct ltc2688_state
> *st)
>   struct ltc2688_chan *chan;
>
>   ret = fwnode_property_read_u32(child, "reg", &reg);
> - if (ret) {
> - fwnode_handle_put(child);
> + if (ret)
>   return dev_err_probe(dev, ret,
>        "Failed to get reg property\n");
> - }
>
> - if (reg >= LTC2688_DAC_CHANNELS) {
> - fwnode_handle_put(child);
> + if (reg >= LTC2688_DAC_CHANNELS)
>   return dev_err_probe(dev, -EINVAL,
>        "reg bigger than: %d\n",
>        LTC2688_DAC_CHANNELS);
> - }
>
>   val = 0;
>   chan = &st->channels[reg];
> @@ -786,12 +782,10 @@ static int ltc2688_channel_config(struct ltc2688_state
> *st)
>   if (!ret) {
>   span = ltc2688_span_lookup(st, (int)tmp[0] / 1000,
>      tmp[1] / 1000);
> - if (span < 0) {
> - fwnode_handle_put(child);
> + if (span < 0)
>   return dev_err_probe(dev, -EINVAL,
>        "output range not
> valid:[%d %d]\n",
>        tmp[0], tmp[1]);
> - }
>
>   val |= FIELD_PREP(LTC2688_CH_SPAN_MSK, span);
>   }
> @@ -800,17 +794,14 @@ static int ltc2688_channel_config(struct ltc2688_state
> *st)
>          &clk_input);
>   if (!ret) {
>   if (clk_input >= LTC2688_CH_TGP_MAX) {

We can now remove the brackets...

> - fwnode_handle_put(child);
>   return dev_err_probe(dev, -EINVAL,
>        "toggle-dither-input inv
> value(%d)\n",
>        clk_input);
>   }
>
>   ret = ltc2688_tgp_clk_setup(st, chan, child,
> clk_input);
> - if (ret) {
> - fwnode_handle_put(child);
> + if (ret)
>   return ret;
> - }
>
>   /*
>   * 0 means software toggle which is the default mode.
> @@ -844,11 +835,9 @@ static int ltc2688_channel_config(struct ltc2688_state
> *st)
>
>   ret = regmap_write(st->regmap, LTC2688_CMD_CH_SETTING(reg),
>      val);
> - if (ret) {
> - fwnode_handle_put(child);
> + if (ret)
>   return dev_err_probe(dev, -EINVAL,
>        "failed to set chan
> settings\n");
> - }
>   }
>
>   return 0;