diff mbox series

ALSA: dmaengine: increment buffer pointer atomically

Message ID 1664211493-11789-1-git-send-email-erosca@de.adit-jv.com (mailing list archive)
State Accepted
Commit d1c442019594692c64a70a86ad88eb5b6db92216
Headers show
Series ALSA: dmaengine: increment buffer pointer atomically | expand

Commit Message

Eugeniu Rosca Sept. 26, 2022, 4:58 p.m. UTC 
From: Andreas Pape <apape@de.adit-jv.com>

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@de.adit-jv.com>
Signed-off-by: Eugeniu Rosca <erosca@de.adit-jv.com>
---
 sound/core/pcm_dmaengine.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

Comments

Takashi Iwai Sept. 27, 2022, 6:55 a.m. UTC | #1 
On Mon, 26 Sep 2022 18:58:13 +0200,
Eugeniu Rosca wrote:
> 
> From: Andreas Pape <apape@de.adit-jv.com>
> 
> 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@de.adit-jv.com>
> Signed-off-by: Eugeniu Rosca <erosca@de.adit-jv.com>

Thanks, applied.


Takashi
diff mbox series

Patch

diff --git a/sound/core/pcm_dmaengine.c b/sound/core/pcm_dmaengine.c
index 5b2ca028f5aa..494ec0c207fa 100644
--- a/sound/core/pcm_dmaengine.c
+++ b/sound/core/pcm_dmaengine.c
@@ -133,12 +133,14 @@  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);
 }