Merge branch 'staging/for_v3.4' into v4l_for_linus

* staging/for_v3.4: (10117 commits)
  [media] update CARDLIST.em28xx
  [media] partially reverts changeset fa5527c
  [media] stb0899: fix the limits for signal strength values
  [media] em28xx: support for 2304:0242 PCTV QuatroStick (510e)
  [media] em28xx: support for 2013:0251 PCTV QuatroStick nano (520e)
  [media] -EINVAL -> -ENOTTY
  [media] gspca - sn9c20x: Cleanup source
  [media] gspca - sn9c20x: Simplify register write for capture start/stop
  [media] gspca - sn9c20x: Add automatic JPEG compression mechanism
  [media] gspca - sn9c20x: Greater delay in case of sensor no response
  [media] gspca - sn9c20x: Optimize the code of write sequences
  [media] gspca - sn9c20x: Add the JPEG compression quality control
  [media] gspca - sn9c20x: Add a delay after Omnivision sensor reset
  [media] gspca - sn9c20x: Propagate USB errors to higher level
  [media] gspca - sn9c20x: Use the new video control mechanism
  [media] gspca - sn9c20x: Fix loss of frame start
  [media] gspca - zc3xx: Lack of register 08 value for sensor cs2102k
  [media] gspca - ov534_9: Add brightness to OmniVision 5621 sensor
  [media] gspca - zc3xx: Add V4L2_CID_JPEG_COMPRESSION_QUALITY control support
  [media] pvrusb2: fix 7MHz & 8MHz DVB-T tuner support for HVR1900 rev D1F5
  ...

1 files changed, 19 insertions, 10 deletions

diff --git a/mm/backing-dev.c b/mm/backing-dev.c
index 71034f41a2ba..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;
 
@@ -600,14 +602,15 @@ 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. Force
-	 * unfreeze of the thread before calling kthread_stop(), otherwise
-	 * it would never exet if it is currently stuck in the refrigerator.
+	 * safe anymore, since the bdi is gone from visibility.
 	 */
-	if (bdi->wb.task) {
-		thaw_process(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);
 }
 
 /*
@@ -627,7 +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);
@@ -636,8 +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);