This is a note to let you know that I've just added the patch titled
ALSA: dmaengine: increment buffer pointer atomically
to the 4.19-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:
alsa-dmaengine-increment-buffer-pointer-atomically.patch
and it can be found in the queue-4.19 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 332864df7b33b479a3a4a18d4269ecac575c8f67
Author: Andreas Pape <apape@xxxxxxxxxxxxxx>
Date: Mon Sep 26 18:58:13 2022 +0200
ALSA: dmaengine: increment buffer pointer atomically
[ Upstream commit d1c442019594692c64a70a86ad88eb5b6db92216 ]
Setting pointer and afterwards checking for wraparound leads
to the possibility of returning the inconsistent pointer position.
This patch increments buffer pointer atomically to avoid this issue.
Fixes: e7f73a1613567a ("ASoC: Add dmaengine PCM helper functions")
Signed-off-by: Andreas Pape <apape@xxxxxxxxxxxxxx>
Signed-off-by: Eugeniu Rosca <erosca@xxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/1664211493-11789-1-git-send-email-erosca@xxxxxxxxxxxxxx
Signed-off-by: Takashi Iwai <tiwai@xxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/sound/core/pcm_dmaengine.c b/sound/core/pcm_dmaengine.c
index 8eb58c709b14..6f6da1128edc 100644
--- a/sound/core/pcm_dmaengine.c
+++ b/sound/core/pcm_dmaengine.c
@@ -139,12 +139,14 @@ EXPORT_SYMBOL_GPL(snd_dmaengine_pcm_set_config_from_dai_data);
static void dmaengine_pcm_dma_complete(void *arg)
{
+ unsigned int new_pos;
struct snd_pcm_substream *substream = arg;
struct dmaengine_pcm_runtime_data *prtd = substream_to_prtd(substream);
- prtd->pos += snd_pcm_lib_period_bytes(substream);
- if (prtd->pos >= snd_pcm_lib_buffer_bytes(substream))
- prtd->pos = 0;
+ new_pos = prtd->pos + snd_pcm_lib_period_bytes(substream);
+ if (new_pos >= snd_pcm_lib_buffer_bytes(substream))
+ new_pos = 0;
+ prtd->pos = new_pos;
snd_pcm_period_elapsed(substream);
}
