From 645ad410dcbd32d2566ada0dd1eb65abfcfa3b9d Mon Sep 17 00:00:00 2001 From: Jiada Wang Date: Thu, 7 Dec 2017 22:15:38 -0800 Subject: [PATCH] ASoC: rsnd: ssi: fix race condition in rsnd_ssi_pointer_update [ Upstream commit 33f801366bdf3f8b67dfe325b84f4051a090d01e ] 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 Reviewed-by: Takashi Sakamoto Acked-by: Kuninori Morimoto Signed-off-by: Mark Brown Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- 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 2aef7c00cca1..f0fb85fda42d 100644 --- a/sound/soc/sh/rcar/ssi.c +++ b/sound/soc/sh/rcar/ssi.c @@ -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; }