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authorJiada Wang <jiada_wang@mentor.com>2017-12-07 22:15:38 -0800
committerMark Brown <broonie@kernel.org>2017-12-08 18:51:32 +0000
commit33f801366bdf3f8b67dfe325b84f4051a090d01e (patch)
tree0f322e9b274164c3bd6e3726cb93ec438deaa493 /sound/soc/sh/rcar
parenta91d7fb97092d6b840af5899ded3b389603fd7f1 (diff)
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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>
Diffstat (limited to 'sound/soc/sh/rcar')
-rw-r--r--sound/soc/sh/rcar/ssi.c16
1 files 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;
}