[6/8] V4L: Events: Count event queue length

Commit Message

Sakari Ailus Feb. 6, 2010, 6:02 p.m. UTC

None

Patch

diff --git a/drivers/media/video/v4l2-event.c b/drivers/media/video/v4l2-event.c
index 7ae763f..b921229 100644
--- a/drivers/media/video/v4l2-event.c
+++ b/drivers/media/video/v4l2-event.c
@@ -107,6 +107,8 @@  int v4l2_event_init(struct v4l2_fh *fh, unsigned int n)
 	INIT_LIST_HEAD(&fh->events->available);
 	INIT_LIST_HEAD(&fh->events->subscribed);
 
+	atomic_set(&fh->events->navailable, 0);
+
 	ret = v4l2_event_alloc(fh, n);
 	if (ret < 0)
 		v4l2_event_exit(fh);
@@ -128,10 +130,12 @@  int v4l2_event_dequeue(struct v4l2_fh *fh, struct v4l2_event *event)
 		return -ENOENT;
 	}
 
+	BUG_ON(&events->navailable == 0);
+
 	kev = list_first_entry(&events->available, struct v4l2_kevent, list);
 	list_del(&kev->list);
 
-	kev->event.count = !list_empty(&events->available);
+	kev->event.count = atomic_dec_return(&events->navailable);
 
 	spin_unlock_irqrestore(&fh->lock, flags);
 
@@ -225,6 +229,8 @@  void v4l2_event_queue(struct video_device *vdev, struct v4l2_event *ev)
 		list_add_tail(&kev->list, &events->available);
 		spin_unlock_irqrestore(&fh->lock, flags);
 
+		atomic_inc(&events->navailable);
+
 		wake_up_all(&events->wait);
 
 		spin_lock_irqsave(&vdev->fhs.lock, flags);
@@ -240,15 +246,7 @@  EXPORT_SYMBOL_GPL(v4l2_event_queue);
 
 int v4l2_event_pending(struct v4l2_fh *fh)
 {
-	struct v4l2_events *events = fh->events;
-	unsigned long flags;
-	int ret;
-
-	spin_lock_irqsave(&fh->lock, flags);
-	ret = !list_empty(&events->available);
-	spin_unlock_irqrestore(&fh->lock, flags);
-
-	return ret;
+	return atomic_read(&fh->events->navailable);
 }
 EXPORT_SYMBOL_GPL(v4l2_event_pending);
 
diff --git a/include/media/v4l2-event.h b/include/media/v4l2-event.h
index 580c9d4..282d215 100644
--- a/include/media/v4l2-event.h
+++ b/include/media/v4l2-event.h
@@ -28,6 +28,8 @@ 
 #include <linux/types.h>
 #include <linux/videodev2.h>
 
+#include <asm/atomic.h>
+
 struct v4l2_fh;
 struct video_device;
 
@@ -45,6 +47,7 @@  struct v4l2_events {
 	wait_queue_head_t	wait;
 	struct list_head	subscribed; /* Subscribed events */
 	struct list_head	available; /* Dequeueable event */
+	atomic_t                navailable;
 	struct list_head	free; /* Events ready for use */
 };