[RFT][PATCH 5/5] ALSA: firewire: use nonatomic PCM operation

[Takashi Sakamoto]

In the former commits, the callback of isochronous context runs on work
process. In the case, ALSA PCM device has a flag, nonatomic, to acquire
mutex lock instead of spin lock for PCM substream group.

This commit uses the flag. It has an advantage in the case that ALSA PCM
application uses the large size of intermediate buffer, since it takes
too long time even in tasklet softIRQ to process many of isochronous
packets. It could result in the delay of system event due to disabled
IRQ so long.

Signed-off-by: Takashi Sakamoto <o-takashi@xxxxxxxxxxxxx>
---
 sound/firewire/amdtp-stream.c            | 9 ++++++++-
 sound/firewire/bebob/bebob_pcm.c         | 1 +
 sound/firewire/dice/dice-pcm.c           | 1 +
 sound/firewire/digi00x/digi00x-pcm.c     | 1 +
 sound/firewire/fireface/ff-pcm.c         | 1 +
 sound/firewire/fireworks/fireworks_pcm.c | 1 +
 sound/firewire/isight.c                  | 1 +
 sound/firewire/motu/motu-pcm.c           | 1 +
 sound/firewire/oxfw/oxfw-pcm.c           | 1 +
 sound/firewire/tascam/tascam-pcm.c       | 1 +
 10 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/sound/firewire/amdtp-stream.c b/sound/firewire/amdtp-stream.c
index c827d7d8d800..7e97ad133874 100644
--- a/sound/firewire/amdtp-stream.c
+++ b/sound/firewire/amdtp-stream.c
@@ -1055,8 +1055,15 @@ static void generate_rx_packet_descs(struct amdtp_stream *s, struct pkt_desc *de
 
 static inline void cancel_stream(struct amdtp_stream *s)
 {
+	struct work_struct *work = current_work();
+
 	s->packet_index = -1;
-	if (in_softirq())
+
+	// Detect work items for any isochronous context. The work item for pcm_period_work()
+	// should be avoided since the call of snd_pcm_period_elapsed() can reach via
+	// snd_pcm_ops.pointer() under acquiring PCM stream(group) lock and causes dead lock at
+	// snd_pcm_stop_xrun().
+	if (work && work != &s->period_work)
 		amdtp_stream_pcm_abort(s);
 	WRITE_ONCE(s->pcm_buffer_pointer, SNDRV_PCM_POS_XRUN);
 }
diff --git a/sound/firewire/bebob/bebob_pcm.c b/sound/firewire/bebob/bebob_pcm.c
index ce49eef0fcba..360ebf3c4ca2 100644
--- a/sound/firewire/bebob/bebob_pcm.c
+++ b/sound/firewire/bebob/bebob_pcm.c
@@ -367,6 +367,7 @@ int snd_bebob_create_pcm_devices(struct snd_bebob *bebob)
 		goto end;
 
 	pcm->private_data = bebob;
+	pcm->nonatomic = true;
 	snprintf(pcm->name, sizeof(pcm->name),
 		 "%s PCM", bebob->card->shortname);
 	snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_PLAYBACK, &playback_ops);
diff --git a/sound/firewire/dice/dice-pcm.c b/sound/firewire/dice/dice-pcm.c
index d64366217d57..2cf2adb48f2a 100644
--- a/sound/firewire/dice/dice-pcm.c
+++ b/sound/firewire/dice/dice-pcm.c
@@ -441,6 +441,7 @@ int snd_dice_create_pcm(struct snd_dice *dice)
 		if (err < 0)
 			return err;
 		pcm->private_data = dice;
+		pcm->nonatomic = true;
 		strcpy(pcm->name, dice->card->shortname);
 
 		if (capture > 0)
diff --git a/sound/firewire/digi00x/digi00x-pcm.c b/sound/firewire/digi00x/digi00x-pcm.c
index 3bd1575c9d9c..85e65cbc00c4 100644
--- a/sound/firewire/digi00x/digi00x-pcm.c
+++ b/sound/firewire/digi00x/digi00x-pcm.c
@@ -350,6 +350,7 @@ int snd_dg00x_create_pcm_devices(struct snd_dg00x *dg00x)
 		return err;
 
 	pcm->private_data = dg00x;
+	pcm->nonatomic = true;
 	snprintf(pcm->name, sizeof(pcm->name),
 		 "%s PCM", dg00x->card->shortname);
 	snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_PLAYBACK, &playback_ops);
diff --git a/sound/firewire/fireface/ff-pcm.c b/sound/firewire/fireface/ff-pcm.c
index ec915671a79b..63457d24a288 100644
--- a/sound/firewire/fireface/ff-pcm.c
+++ b/sound/firewire/fireface/ff-pcm.c
@@ -390,6 +390,7 @@ int snd_ff_create_pcm_devices(struct snd_ff *ff)
 		return err;
 
 	pcm->private_data = ff;
+	pcm->nonatomic = true;
 	snprintf(pcm->name, sizeof(pcm->name),
 		 "%s PCM", ff->card->shortname);
 	snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_PLAYBACK, &pcm_playback_ops);
diff --git a/sound/firewire/fireworks/fireworks_pcm.c b/sound/firewire/fireworks/fireworks_pcm.c
index c3c21860b245..eaf7778211de 100644
--- a/sound/firewire/fireworks/fireworks_pcm.c
+++ b/sound/firewire/fireworks/fireworks_pcm.c
@@ -397,6 +397,7 @@ int snd_efw_create_pcm_devices(struct snd_efw *efw)
 		goto end;
 
 	pcm->private_data = efw;
+	pcm->nonatomic = true;
 	snprintf(pcm->name, sizeof(pcm->name), "%s PCM", efw->card->shortname);
 	snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_PLAYBACK, &playback_ops);
 	snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_CAPTURE, &capture_ops);
diff --git a/sound/firewire/isight.c b/sound/firewire/isight.c
index 806f82c9ceee..b1e059f0d473 100644
--- a/sound/firewire/isight.c
+++ b/sound/firewire/isight.c
@@ -454,6 +454,7 @@ static int isight_create_pcm(struct isight *isight)
 	if (err < 0)
 		return err;
 	pcm->private_data = isight;
+	pcm->nonatomic = true;
 	strcpy(pcm->name, "iSight");
 	isight->pcm = pcm->streams[SNDRV_PCM_STREAM_CAPTURE].substream;
 	isight->pcm->ops = &ops;
diff --git a/sound/firewire/motu/motu-pcm.c b/sound/firewire/motu/motu-pcm.c
index d410c2efbde5..f3b48495acae 100644
--- a/sound/firewire/motu/motu-pcm.c
+++ b/sound/firewire/motu/motu-pcm.c
@@ -360,6 +360,7 @@ int snd_motu_create_pcm_devices(struct snd_motu *motu)
 	if (err < 0)
 		return err;
 	pcm->private_data = motu;
+	pcm->nonatomic = true;
 	strcpy(pcm->name, motu->card->shortname);
 
 	snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_CAPTURE, &capture_ops);
diff --git a/sound/firewire/oxfw/oxfw-pcm.c b/sound/firewire/oxfw/oxfw-pcm.c
index 5f43a0b826d2..8ca9dde54ec6 100644
--- a/sound/firewire/oxfw/oxfw-pcm.c
+++ b/sound/firewire/oxfw/oxfw-pcm.c
@@ -440,6 +440,7 @@ int snd_oxfw_create_pcm(struct snd_oxfw *oxfw)
 		return err;
 
 	pcm->private_data = oxfw;
+	pcm->nonatomic = true;
 	strcpy(pcm->name, oxfw->card->shortname);
 	snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_PLAYBACK, &playback_ops);
 	if (cap > 0)
diff --git a/sound/firewire/tascam/tascam-pcm.c b/sound/firewire/tascam/tascam-pcm.c
index f6da571707ac..a73003ac11e6 100644
--- a/sound/firewire/tascam/tascam-pcm.c
+++ b/sound/firewire/tascam/tascam-pcm.c
@@ -279,6 +279,7 @@ int snd_tscm_create_pcm_devices(struct snd_tscm *tscm)
 		return err;
 
 	pcm->private_data = tscm;
+	pcm->nonatomic = true;
 	snprintf(pcm->name, sizeof(pcm->name),
 		 "%s PCM", tscm->card->shortname);
 	snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_PLAYBACK, &playback_ops);
-- 
2.43.0