Merge tag 'asoc-3.4' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/sound into topic/asoc

This has been a very active release for ASoC, as well as the usual raft
of bugfixes and driver updates there's quite a few framework enhancements.
Most are either small or are laying the groundwork for user visible
features (especially dynamic PCM), the most directly visible change is
the dmaengine library.  There's also a bunch of regmap API enhancements
pulled into the tree so that either the framework or drivers can take
advantage of the new features.

Changes include:

- Support for widgets not associated with a CODEC, an important part of
  the dynamic PCM framework.

- A library factoring out the common code shared by dmaengine based DMA
  drivers contributed by Lars-Peter Clausen.  This will save a lot of
  code and make it much easier to deploy enhancements to dmaengine.

- Support for binary controls, used for providing runtime configuration
  of algorithm coefficients.

- A new DAPM widget type for regulator supplies allowing drivers for
  devices that can power down unused supplies while active to do without
  any per-driver code.

- DAPM widgets for DAIs, initially giving a speed boost for playback
  startup and shutdown and also the basis for CODEC<->CODEC DAI link
  support.

- Support for specifying the number of significant bits on audio
  interfaces, useful for allowing applications to know how much effort to
  put into generating data for a larger sample format.

- Conversion of the FSI driver used on some SH processors to DMAEngine.

- New CODEC drivers for Maxim MAX9768 and Wolfson Microelectronics WM2200.

1 files changed, 18 insertions, 5 deletions

diff --git a/mm/backing-dev.c b/mm/backing-dev.c
index 7ba8feae11b8..dd8e2aafb07e 100644
--- a/mm/backing-dev.c
+++ b/mm/backing-dev.c
@@ -318,7 +318,7 @@ static void wakeup_timer_fn(unsigned long data)
 	if (bdi->wb.task) {
 		trace_writeback_wake_thread(bdi);
 		wake_up_process(bdi->wb.task);
-	} else {
+	} else if (bdi->dev) {
 		/*
 		 * When bdi tasks are inactive for long time, they are killed.
 		 * In this case we have to wake-up the forker thread which
@@ -584,6 +584,8 @@ EXPORT_SYMBOL(bdi_register_dev);
  */
 static void bdi_wb_shutdown(struct backing_dev_info *bdi)
 {
+	struct task_struct *task;
+
 	if (!bdi_cap_writeback_dirty(bdi))
 		return;
 
@@ -602,8 +604,13 @@ static void bdi_wb_shutdown(struct backing_dev_info *bdi)
 	 * Finally, kill the kernel thread. We don't need to be RCU
 	 * safe anymore, since the bdi is gone from visibility.
 	 */
-	if (bdi->wb.task)
-		kthread_stop(bdi->wb.task);
+	spin_lock_bh(&bdi->wb_lock);
+	task = bdi->wb.task;
+	bdi->wb.task = NULL;
+	spin_unlock_bh(&bdi->wb_lock);
+
+	if (task)
+		kthread_stop(task);
 }
 
 /*
@@ -623,7 +630,9 @@ static void bdi_prune_sb(struct backing_dev_info *bdi)
 
 void bdi_unregister(struct backing_dev_info *bdi)
 {
-	if (bdi->dev) {
+	struct device *dev = bdi->dev;
+
+	if (dev) {
 		bdi_set_min_ratio(bdi, 0);
 		trace_writeback_bdi_unregister(bdi);
 		bdi_prune_sb(bdi);
@@ -632,8 +641,12 @@ void bdi_unregister(struct backing_dev_info *bdi)
 		if (!bdi_cap_flush_forker(bdi))
 			bdi_wb_shutdown(bdi);
 		bdi_debug_unregister(bdi);
-		device_unregister(bdi->dev);
+
+		spin_lock_bh(&bdi->wb_lock);
 		bdi->dev = NULL;
+		spin_unlock_bh(&bdi->wb_lock);
+
+		device_unregister(dev);
 	}
 }
 EXPORT_SYMBOL(bdi_unregister);