This is a note to let you know that I've just added the patch titled
ASoC: rsnd: ssi: fix race condition in rsnd_ssi_pointer_update
to the 4.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
asoc-rsnd-ssi-fix-race-condition-in-rsnd_ssi_pointer_update.patch
and it can be found in the queue-4.14 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From foo@baz Fri Feb 23 11:45:09 CET 2018
From: Jiada Wang <jiada_wang@xxxxxxxxxx>
Date: Thu, 7 Dec 2017 22:15:38 -0800
Subject: ASoC: rsnd: ssi: fix race condition in rsnd_ssi_pointer_update
From: Jiada Wang <jiada_wang@xxxxxxxxxx>
[ 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 <jiada_wang@xxxxxxxxxx>
Reviewed-by: Takashi Sakamoto <takashi.sakamoto@xxxxxxxxxxxxxxxx>
Acked-by: Kuninori Morimoto <kuninori.morimoto.gx@xxxxxxxxxxx>
Signed-off-by: Mark Brown <broonie@xxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
sound/soc/sh/rcar/ssi.c | 16 ++++++++++------
1 file changed, 10 insertions(+), 6 deletions(-)
--- a/sound/soc/sh/rcar/ssi.c
+++ b/sound/soc/sh/rcar/ssi.c
@@ -449,25 +449,29 @@ static bool rsnd_ssi_pointer_update(stru
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_
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;
}
Patches currently in stable-queue which might be from jiada_wang@xxxxxxxxxx are
queue-4.14/asoc-rsnd-ssi-fix-race-condition-in-rsnd_ssi_pointer_update.patch