[PATCH alsa-lib v2 3/3] pcm: direct: Check xrun/suspend before the slave hwptr update

[Takashi Iwai]

The xrun/suspend may happen at any time and we should check it right
after the slave hwptr update (but before the actual sync_ptr update in
direct pcm side).  Otherwise the hwptr value may be screwed and get
unexpected large read/write.

Reported-by: S.J. Wang <shengjiu.wang at nxp.com>
Signed-off-by: Takashi Iwai <tiwai at suse.de>
---
 src/pcm/pcm_dmix.c   | 8 +++++---
 src/pcm/pcm_dshare.c | 8 +++++---
 src/pcm/pcm_dsnoop.c | 6 +++---
 3 files changed, 13 insertions(+), 9 deletions(-)

diff --git a/src/pcm/pcm_dmix.c b/src/pcm/pcm_dmix.c
index d00d53bef604..c6cb47f0f840 100644
--- a/src/pcm/pcm_dmix.c
+++ b/src/pcm/pcm_dmix.c
@@ -424,15 +424,17 @@ static int snd_pcm_dmix_sync_ptr0(snd_pcm_t *pcm, snd_pcm_uframes_t slave_hw_ptr
 static int snd_pcm_dmix_sync_ptr(snd_pcm_t *pcm)
 {
 	snd_pcm_direct_t *dmix = pcm->private_data;
+	snd_pcm_uframes_t slave_hw_ptr;
 	int err;
 
+	if (dmix->slowptr)
+		snd_pcm_hwsync(dmix->spcm);
+	slave_hw_ptr = *dmix->spcm->hw.ptr;
 	err = snd_pcm_direct_check_xrun(dmix, pcm);
 	if (err < 0)
 		return err;
-	if (dmix->slowptr)
-		snd_pcm_hwsync(dmix->spcm);
 
-	return snd_pcm_dmix_sync_ptr0(pcm, *dmix->spcm->hw.ptr);
+	return snd_pcm_dmix_sync_ptr0(pcm, slave_hw_ptr);
 }
 
 /*
diff --git a/src/pcm/pcm_dshare.c b/src/pcm/pcm_dshare.c
index 0ff43a90d270..461adafc77f8 100644
--- a/src/pcm/pcm_dshare.c
+++ b/src/pcm/pcm_dshare.c
@@ -199,15 +199,17 @@ static int snd_pcm_dshare_sync_ptr0(snd_pcm_t *pcm, snd_pcm_uframes_t slave_hw_p
 static int snd_pcm_dshare_sync_ptr(snd_pcm_t *pcm)
 {
 	snd_pcm_direct_t *dshare = pcm->private_data;
+	snd_pcm_uframes_t slave_hw_ptr;
 	int err;
 
+	if (dshare->slowptr)
+		snd_pcm_hwsync(dshare->spcm);
+	slave_hw_ptr = *dshare->spcm->hw.ptr;
 	err = snd_pcm_direct_check_xrun(dshare, pcm);
 	if (err < 0)
 		return err;
-	if (dshare->slowptr)
-		snd_pcm_hwsync(dshare->spcm);
 
-	return snd_pcm_dshare_sync_ptr0(pcm, *dshare->spcm->hw.ptr);
+	return snd_pcm_dshare_sync_ptr0(pcm, slave_hw_ptr);
 }
 
 /*
diff --git a/src/pcm/pcm_dsnoop.c b/src/pcm/pcm_dsnoop.c
index 729ff447b41f..9abbbef2c1b6 100644
--- a/src/pcm/pcm_dsnoop.c
+++ b/src/pcm/pcm_dsnoop.c
@@ -134,14 +134,14 @@ static int snd_pcm_dsnoop_sync_ptr(snd_pcm_t *pcm)
 	snd_pcm_sframes_t diff;
 	int err;
 
-	err = snd_pcm_direct_check_xrun(dsnoop, pcm);
-	if (err < 0)
-		return err;
 	if (dsnoop->slowptr)
 		snd_pcm_hwsync(dsnoop->spcm);
 	old_slave_hw_ptr = dsnoop->slave_hw_ptr;
 	snoop_timestamp(pcm);
 	slave_hw_ptr = dsnoop->slave_hw_ptr;
+	err = snd_pcm_direct_check_xrun(dsnoop, pcm);
+	if (err < 0)
+		return err;
 	diff = pcm_frame_diff(slave_hw_ptr, old_slave_hw_ptr, dsnoop->slave_boundary);
 	if (diff == 0)		/* fast path */
 		return 0;
-- 
2.34.1