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, 40 insertions, 8 deletions

diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index 1da999f5e74..0f0d4704ddd 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -985,6 +985,11 @@ __setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new)
 
 		/* add new interrupt at end of irq queue */
 		do {
+			/*
+			 * Or all existing action->thread_mask bits,
+			 * so we can find the next zero bit for this
+			 * new action.
+			 */
 			thread_mask |= old->thread_mask;
 			old_ptr = &old->next;
 			old = *old_ptr;
@@ -993,14 +998,41 @@ __setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new)
 	}
 
 	/*
-	 * Setup the thread mask for this irqaction. Unlikely to have
-	 * 32 resp 64 irqs sharing one line, but who knows.
+	 * Setup the thread mask for this irqaction for ONESHOT. For
+	 * !ONESHOT irqs the thread mask is 0 so we can avoid a
+	 * conditional in irq_wake_thread().
 	 */
-	if (new->flags & IRQF_ONESHOT && thread_mask == ~0UL) {
-		ret = -EBUSY;
-		goto out_mask;
+	if (new->flags & IRQF_ONESHOT) {
+		/*
+		 * Unlikely to have 32 resp 64 irqs sharing one line,
+		 * but who knows.
+		 */
+		if (thread_mask == ~0UL) {
+			ret = -EBUSY;
+			goto out_mask;
+		}
+		/*
+		 * The thread_mask for the action is or'ed to
+		 * desc->thread_active to indicate that the
+		 * IRQF_ONESHOT thread handler has been woken, but not
+		 * yet finished. The bit is cleared when a thread
+		 * completes. When all threads of a shared interrupt
+		 * line have completed desc->threads_active becomes
+		 * zero and the interrupt line is unmasked. See
+		 * handle.c:irq_wake_thread() for further information.
+		 *
+		 * If no thread is woken by primary (hard irq context)
+		 * interrupt handlers, then desc->threads_active is
+		 * also checked for zero to unmask the irq line in the
+		 * affected hard irq flow handlers
+		 * (handle_[fasteoi|level]_irq).
+		 *
+		 * The new action gets the first zero bit of
+		 * thread_mask assigned. See the loop above which or's
+		 * all existing action->thread_mask bits.
+		 */
+		new->thread_mask = 1 << ffz(thread_mask);
 	}
-	new->thread_mask = 1 << ffz(thread_mask);
 
 	if (!shared) {
 		init_waitqueue_head(&desc->wait_for_threads);
@@ -1027,7 +1059,7 @@ __setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new)
 			desc->istate |= IRQS_ONESHOT;
 
 		if (irq_settings_can_autoenable(desc))
-			irq_startup(desc);
+			irq_startup(desc, true);
 		else
 			/* Undo nested disables: */
 			desc->depth = 1;
@@ -1292,7 +1324,7 @@ EXPORT_SYMBOL(free_irq);
  *	and to set up the interrupt handler in the right order.
  *
  *	If you want to set up a threaded irq handler for your device
- *	then you need to supply @handler and @thread_fn. @handler ist
+ *	then you need to supply @handler and @thread_fn. @handler is
  *	still called in hard interrupt context and has to check
  *	whether the interrupt originates from the device. If yes it
  *	needs to disable the interrupt on the device and return