ASoC: rsnd: ssi: fix race condition in rsnd_ssi_pointer_update (33f80136) · Commits · 戴 / test

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

+10 −6

Original line number	Diff line number	Diff line
		@@ -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;
		}

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