From: Takashi Iwai <tiwai@suse.de>
Subject: ALSA: hda - Use own workqueue
Patch-mainline: 2.6.29-rc2
References: bnc#502733

snd-hda-intel driver used schedule_work() fot the delayed DMA pointer
updates, but this has several potential problems:
- it may block other eventsd works longer
- it may deadlock when probing fails and flush_scheduled_work() is
  called during probe callback (as probe callback itself could be
  invoked from eventd)

This patch adds an own workq for each driver instance to solve these
problems.

Signed-off-by: Takashi Iwai <tiwai@suse.de>

---
 sound/pci/hda/hda_beep.c  |    1 -
 sound/pci/hda/hda_codec.c |   24 ++++++++++++++++++------
 sound/pci/hda/hda_codec.h |    2 ++
 sound/pci/hda/hda_intel.c |    6 +++---
 4 files changed, 23 insertions(+), 10 deletions(-)

--- a/sound/pci/hda/hda_beep.c
+++ b/sound/pci/hda/hda_beep.c
@@ -134,7 +134,6 @@
 	struct hda_beep *beep = codec->beep;
 	if (beep) {
 		cancel_work_sync(&beep->beep_work);
-		flush_scheduled_work();
 
 		input_unregister_device(beep->dev);
 		kfree(beep);
--- a/sound/pci/hda/hda_codec.c
+++ b/sound/pci/hda/hda_codec.c
@@ -310,7 +310,7 @@
 	unsol->queue[wp] = res;
 	unsol->queue[wp + 1] = res_ex;
 
-	schedule_work(&unsol->work);
+	queue_work(bus->workq, &unsol->work);
 
 	return 0;
 }
@@ -373,15 +373,17 @@
 
 	if (!bus)
 		return 0;
-	if (bus->unsol) {
-		flush_scheduled_work();
+	if (bus->workq)
+		flush_workqueue(bus->workq);
+	if (bus->unsol)
 		kfree(bus->unsol);
-	}
 	list_for_each_entry_safe(codec, n, &bus->codec_list, list) {
 		snd_hda_codec_free(codec);
 	}
 	if (bus->ops.private_free)
 		bus->ops.private_free(bus);
+	if (bus->workq)
+		destroy_workqueue(bus->workq);
 	kfree(bus);
 	return 0;
 }
@@ -431,6 +433,16 @@
 	mutex_init(&bus->cmd_mutex);
 	INIT_LIST_HEAD(&bus->codec_list);
 
+	snprintf(bus->workq_name, sizeof(bus->workq_name),
+		 "hd-audio%d", card->number);
+	bus->workq = create_singlethread_workqueue(bus->workq_name);
+	if (!bus->workq) {
+		snd_printk(KERN_ERR "cannot create workqueue %s\n",
+			   bus->workq_name);
+		kfree(bus);
+		return -ENOMEM;
+	}
+
 	err = snd_device_new(card, SNDRV_DEV_BUS, bus, &dev_ops);
 	if (err < 0) {
 		snd_hda_bus_free(bus);
@@ -564,7 +576,7 @@
 		return;
 #ifdef CONFIG_SND_HDA_POWER_SAVE
 	cancel_delayed_work(&codec->power_work);
-	flush_scheduled_work();
+	flush_workqueue(codec->bus->workq);
 #endif
 	list_del(&codec->list);
 	codec->bus->caddr_tbl[codec->addr] = NULL;
@@ -2533,7 +2545,7 @@
 		return;
 	if (power_save) {
 		codec->power_transition = 1; /* avoid reentrance */
-		schedule_delayed_work(&codec->power_work,
+		queue_delayed_work(codec->bus->workq, &codec->power_work,
 				      msecs_to_jiffies(power_save * 1000));
 	}
 }
--- a/sound/pci/hda/hda_codec.h
+++ b/sound/pci/hda/hda_codec.h
@@ -580,6 +580,8 @@
 
 	/* unsolicited event queue */
 	struct hda_bus_unsolicited *unsol;
+	char workq_name[16];
+	struct workqueue_struct *workq;	/* common workqueue for codecs */
 
 	struct snd_info_entry *proc;
 
--- a/sound/pci/hda/hda_intel.c
+++ b/sound/pci/hda/hda_intel.c
@@ -986,10 +986,11 @@
 				spin_unlock(&chip->reg_lock);
 				snd_pcm_period_elapsed(azx_dev->substream);
 				spin_lock(&chip->reg_lock);
-			} else {
+			} else if (chip->bus && chip->bus->workq) {
 				/* bogus IRQ, process it later */
 				azx_dev->irq_pending = 1;
-				schedule_work(&chip->irq_pending_work);
+				queue_work(chip->bus->workq,
+					   &chip->irq_pending_work);
 			}
 		}
 	}
@@ -1708,7 +1709,6 @@
 	for (i = 0; i < chip->num_streams; i++)
 		chip->azx_dev[i].irq_pending = 0;
 	spin_unlock_irq(&chip->reg_lock);
-	flush_scheduled_work();
 }
 
 static struct snd_pcm_ops azx_pcm_ops = {