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Commit 645ad410 authored by Jiada Wang's avatar Jiada Wang Committed by Greg Kroah-Hartman
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ASoC: rsnd: ssi: fix race condition in rsnd_ssi_pointer_update 




[ Upstream commit 33f80136 ]

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: default avatarJiada Wang <jiada_wang@mentor.com>
Reviewed-by: default avatarTakashi Sakamoto <takashi.sakamoto@miraclelinux.com>
Acked-by: default avatarKuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: default avatarMark Brown <broonie@kernel.org>
Signed-off-by: default avatarSasha Levin <alexander.levin@verizon.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 06078bd6

sound/soc/sh/rcar/ssi.c

+10 −6
Original line number Diff line number Diff line
@@ -449,25 +449,29 @@ 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;

}