Re: [alsa-devel] Applied "ASoC: rsnd: ssi: fix race condition in rsnd_ssi_pointer_update" to the asoc tree

Hi Mark,

On Dec 9 2017 03:52, Mark Brown wrote:

The patch

ASoC: rsnd: ssi: fix race condition in rsnd_ssi_pointer_update

has been applied to the asoc tree at

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

The applied patches are in v1 patchset, but we have v2 patchset already: http://mailman.alsa-project.org/pipermail/alsa-devel/2017-December/128970.ht...

Would you please replace the applied patches with the renewed ones? There're slight differences between them.

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 to this mail.

Thanks, Mark

...

From 33f801366bdf3f8b67dfe325b84f4051a090d01e Mon Sep 17 00:00:00 2001

From: Jiada Wang jiada_wang@mentor.com Date: Thu, 7 Dec 2017 22:15:38 -0800 Subject: [PATCH] ASoC: rsnd: ssi: fix race condition in rsnd_ssi_pointer_update

Currently there is race condition between set of byte_pos and wrap it around when new buffer starts. If .pointer is called in-between it will result in inconsistent pointer position be returned from .pointer callback.

This patch increments buffer pointer atomically to avoid this issue.

Signed-off-by: Jiada Wang jiada_wang@mentor.com Reviewed-by: Takashi Sakamoto takashi.sakamoto@miraclelinux.com Acked-by: Kuninori Morimoto kuninori.morimoto.gx@renesas.com Signed-off-by: Mark Brown broonie@kernel.org

---

sound/soc/sh/rcar/ssi.c | 16 ++++++++++------ 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/sound/soc/sh/rcar/ssi.c b/sound/soc/sh/rcar/ssi.c index fece1e5f582f..cbf3bf312d23 100644 --- a/sound/soc/sh/rcar/ssi.c +++ b/sound/soc/sh/rcar/ssi.c @@ -446,25 +446,29 @@ static bool rsnd_ssi_pointer_update(struct rsnd_mod *mod, int byte) { struct rsnd_ssi *ssi = rsnd_mod_to_ssi(mod);

• bool ret = false;
• int byte_pos;

• ssi->byte_pos += byte;

• byte_pos = ssi->byte_pos + byte;

• if (ssi->byte_pos >= ssi->next_period_byte) {

• if (byte_pos >= ssi->next_period_byte) { struct snd_pcm_runtime *runtime = rsnd_io_to_runtime(io);

  ssi->period_pos++; ssi->next_period_byte += ssi->byte_per_period;

  if (ssi->period_pos >= runtime->periods) {

• 	ssi->byte_pos = 0;
  

• 	byte_pos = 0;
  ssi->period_pos = 0;
  ssi->next_period_byte = ssi->byte_per_period;
  

  }

• return true;
  

• ret = true;
  

  }

• return false;

• WRITE_ONCE(ssi->byte_pos, byte_pos);

• return ret; }

  /*

@@ -838,7 +842,7 @@ static int rsnd_ssi_pointer(struct rsnd_mod *mod, struct rsnd_ssi *ssi = rsnd_mod_to_ssi(mod); struct snd_pcm_runtime *runtime = rsnd_io_to_runtime(io);

• *pointer = bytes_to_frames(runtime, ssi->byte_pos);

• *pointer = bytes_to_frames(runtime, READ_ONCE(ssi->byte_pos));

  return 0; }

Thanks

Takashi Sakamoto