diff mbox

Bug in snd_pcm_ioplug_avail_update()?

Message ID dw77emr2k1eug4.fsf@tesla.com (mailing list archive)
State New, archived
Headers show

Commit Message

Rob Duncan July 17, 2018, 3:46 p.m. UTC 
At 22:04 on Mon, Jul 16 2018, Takashi wrote:

> The code change is similar as what I had in my mind, but...

Version 2!

Thanks,

Rob.

From 8890fbf81c27ed5fded12349b274c7c008c53249 Mon Sep 17 00:00:00 2001
From: Rob Duncan <rduncan@teslamotors.com>
Date: Mon, 16 Jul 2018 16:35:23 -0700
Subject: [PATCH] pcm: ioplug: Transfer all available data

The snd_pcm_mmap_begin() call returns the amount of contiguous data,
which is less than the total available if it wraps around the buffer
boundary.

If we don't handle this split we leave stale data in the buffer that
should have been overwritten, as well as unread data in the io_plugin
that gets transferred on a subsequent call at the wrong offset.

Signed-off-by: Rob Duncan <rduncan@teslamotors.com>
---
 src/pcm/pcm_ioplug.c | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

Comments

Takashi Iwai July 17, 2018, 3:54 p.m. UTC | #1 
On Tue, 17 Jul 2018 17:46:35 +0200,
Rob Duncan wrote:
> 
> At 22:04 on Mon, Jul 16 2018, Takashi wrote:
> 
> > The code change is similar as what I had in my mind, but...
> 
> Version 2!

Applied, thanks!


Takashi
diff mbox

Patch

diff --git a/src/pcm/pcm_ioplug.c b/src/pcm/pcm_ioplug.c
index 6d52c27b..881a1a85 100644
--- a/src/pcm/pcm_ioplug.c
+++ b/src/pcm/pcm_ioplug.c
@@ -716,6 +716,8 @@  static snd_pcm_sframes_t snd_pcm_ioplug_avail_update(snd_pcm_t *pcm)
 	snd_pcm_ioplug_hw_ptr_update(pcm);
 	if (io->data->state == SND_PCM_STATE_XRUN)
 		return -EPIPE;
+
+	avail = snd_pcm_mmap_avail(pcm);
 	if (pcm->stream == SND_PCM_STREAM_CAPTURE &&
 	    pcm->access != SND_PCM_ACCESS_RW_INTERLEAVED &&
 	    pcm->access != SND_PCM_ACCESS_RW_NONINTERLEAVED) {
@@ -728,9 +730,19 @@  static snd_pcm_sframes_t snd_pcm_ioplug_avail_update(snd_pcm_t *pcm)
 			result = io->data->callback->transfer(io->data, areas, offset, size);
 			if (result < 0)
 				return result;
+
+			/* If the available data doesn't fit in the
+			   contiguous area at the end of the mmap we
+			   must transfer the remaining data to the
+			   beginning of the mmap. */
+			if (size < avail) {
+				result = io->data->callback->transfer(io->data, areas,
+								      0, avail - size);
+				if (result < 0)
+					return result;
+			}
 		}
 	}
-	avail = snd_pcm_mmap_avail(pcm);
 	if (avail > io->avail_max)
 		io->avail_max = avail;
 	return (snd_pcm_sframes_t)avail;