ASoC: audio-iio-aux: Use flex array to simplify code

Commit Message

Christophe JAILLET Sept. 24, 2023, 7:36 a.m. UTC

"io-channel-names" is expected to have few values, so there is no real
point to allocate audio_iio_aux_chan structure with a dedicate memory
allocation.

Using a flexible array for struct audio_iio_aux->chans avoids the
overhead of an additional, managed, memory allocation.

This also saves an indirection when the array is accessed.

Finally, __counted_by() can be used for run-time bounds checking if
configured and supported by the compiler.

Signed-off-by: Christophe JAILLET <[e-mail]>
---
 sound/soc/codecs/audio-iio-aux.c | 17 ++++++-----------
 1 file changed, 6 insertions(+), 11 deletions(-)

Comments

Mark Brown Sept. 25, 2023, 3:33 p.m. UTC | #1

On Sun, 24 Sep 2023 09:36:01 +0200, Christophe JAILLET wrote:
> "io-channel-names" is expected to have few values, so there is no real
> point to allocate audio_iio_aux_chan structure with a dedicate memory
> allocation.
> 
> Using a flexible array for struct audio_iio_aux->chans avoids the
> overhead of an additional, managed, memory allocation.
> 
> [...]

Applied to

   https://git.kernel.org/pub/scm/linux/kernel/git/broonie/sound.git for-next

Thanks!

[1/1] ASoC: audio-iio-aux: Use flex array to simplify code
      commit: c351835058419c1eb8791941a057c3f3e6068cb6

All being well this means that it will be integrated into the linux-next
tree (usually sometime in the next 24 hours) and sent to Linus during
the next merge window (or sooner if it is a bug fix), however if
problems are discovered then the patch may be dropped or reverted.

You may get further e-mails resulting from automated or manual testing
and review of the tree, please engage with people reporting problems and
send followup patches addressing any issues that are reported if needed.

If any updates are required or you are submitting further changes they
should be sent as incremental updates against current git, existing
patches will not be replaced.

Please add any relevant lists and maintainers to the CCs when replying
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Thanks,
Mark

Patch

diff --git a/sound/soc/codecs/audio-iio-aux.c b/sound/soc/codecs/audio-iio-aux.c
index a8bf14239bd7..1e8e1effc2af 100644
--- a/sound/soc/codecs/audio-iio-aux.c
+++ b/sound/soc/codecs/audio-iio-aux.c
@@ -26,8 +26,8 @@  struct audio_iio_aux_chan {
 
 struct audio_iio_aux {
 	struct device *dev;
-	struct audio_iio_aux_chan *chans;
 	unsigned int num_chans;
+	struct audio_iio_aux_chan chans[]  __counted_by(num_chans);
 };
 
 static int audio_iio_aux_info_volsw(struct snd_kcontrol *kcontrol,
@@ -250,23 +250,18 @@  static int audio_iio_aux_probe(struct platform_device *pdev)
 	int ret;
 	int i;
 
-	iio_aux = devm_kzalloc(dev, sizeof(*iio_aux), GFP_KERNEL);
+	count = device_property_string_array_count(dev, "io-channel-names");
+	if (count < 0)
+		return dev_err_probe(dev, count, "failed to count io-channel-names\n");
+
+	iio_aux = devm_kzalloc(dev, struct_size(iio_aux, chans, count), GFP_KERNEL);
 	if (!iio_aux)
 		return -ENOMEM;
 
 	iio_aux->dev = dev;
 
-	count = device_property_string_array_count(dev, "io-channel-names");
-	if (count < 0)
-		return dev_err_probe(dev, count, "failed to count io-channel-names\n");
-
 	iio_aux->num_chans = count;
 
-	iio_aux->chans = devm_kmalloc_array(dev, iio_aux->num_chans,
-					    sizeof(*iio_aux->chans), GFP_KERNEL);
-	if (!iio_aux->chans)
-		return -ENOMEM;
-
 	names = kcalloc(iio_aux->num_chans, sizeof(*names), GFP_KERNEL);
 	if (!names)
 		return -ENOMEM;