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ASoC: rsnd: ssi: fix race condition in rsnd_ssi_pointer_update 

[ Upstream commit 33f801366b ]

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>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Jiada Wang 2017-12-07 22:15:38 -08:00 committed by Greg Kroah-Hartman
parent 06078bd640
commit 645ad410dc
1 changed files with 10 additions and 6 deletions
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16
sound/soc/sh/rcar/ssi.c
View File

@ -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;
}