When unregistering a V4L2 device node, make sure any filehandles
that are waiting for an event are woken up.
Add v4l2_event_wake_all() to v4l2-event.c and call it from
video_unregister_device().
Otherwise userspace might never know that a device node was removed.
Signed-off-by: Hans Verkuil <hverkuil-cisco@xxxxxxxxx>
---
drivers/media/v4l2-core/v4l2-dev.c | 3 +++
drivers/media/v4l2-core/v4l2-event.c | 17 +++++++++++++++++
include/media/v4l2-event.h | 13 +++++++++++--
3 files changed, 31 insertions(+), 2 deletions(-)
diff --git a/drivers/media/v4l2-core/v4l2-dev.c b/drivers/media/v4l2-core/v4l2-dev.c
index a593ea0598b5..0ddc3554f1a4 100644
--- a/drivers/media/v4l2-core/v4l2-dev.c
+++ b/drivers/media/v4l2-core/v4l2-dev.c
@@ -28,6 +28,7 @@
#include <media/v4l2-common.h>
#include <media/v4l2-device.h>
#include <media/v4l2-ioctl.h>
+#include <media/v4l2-event.h>
#define VIDEO_NUM_DEVICES 256
#define VIDEO_NAME "video4linux"
@@ -1086,6 +1087,8 @@ void video_unregister_device(struct video_device *vdev)
*/
clear_bit(V4L2_FL_REGISTERED, &vdev->flags);
mutex_unlock(&videodev_lock);
+ if (test_bit(V4L2_FL_USES_V4L2_FH, &vdev->flags))
+ v4l2_event_wake_all(vdev);
device_unregister(&vdev->dev);
}
EXPORT_SYMBOL(video_unregister_device);
diff --git a/drivers/media/v4l2-core/v4l2-event.c b/drivers/media/v4l2-core/v4l2-event.c
index 290c6b213179..207a9ad80ea2 100644
--- a/drivers/media/v4l2-core/v4l2-event.c
+++ b/drivers/media/v4l2-core/v4l2-event.c
@@ -187,6 +187,23 @@ int v4l2_event_pending(struct v4l2_fh *fh)
}
EXPORT_SYMBOL_GPL(v4l2_event_pending);
+void v4l2_event_wake_all(struct video_device *vdev)
+{
+ struct v4l2_fh *fh;
+ unsigned long flags;
+
+ if (vdev == NULL)
+ return;
+
+ spin_lock_irqsave(&vdev->fh_lock, flags);
+
+ list_for_each_entry(fh, &vdev->fh_list, list)
+ wake_up_all(&fh->wait);
+
+ spin_unlock_irqrestore(&vdev->fh_lock, flags);
+}
+EXPORT_SYMBOL_GPL(v4l2_event_wake_all);
+
static void __v4l2_event_unsubscribe(struct v4l2_subscribed_event *sev)
{
struct v4l2_fh *fh = sev->fh;
diff --git a/include/media/v4l2-event.h b/include/media/v4l2-event.h
index 3f0281d06ec7..4ffa914ade3a 100644
--- a/include/media/v4l2-event.h
+++ b/include/media/v4l2-event.h
@@ -101,7 +101,7 @@ int v4l2_event_dequeue(struct v4l2_fh *fh, struct v4l2_event *event,
*
* .. note::
* The driver's only responsibility is to fill in the type and the data
- * fields.The other fields will be filled in by V4L2.
+ * fields. The other fields will be filled in by V4L2.
*/
void v4l2_event_queue(struct video_device *vdev, const struct v4l2_event *ev);
@@ -116,10 +116,19 @@ void v4l2_event_queue(struct video_device *vdev, const struct v4l2_event *ev);
*
* .. note::
* The driver's only responsibility is to fill in the type and the data
- * fields.The other fields will be filled in by V4L2.
+ * fields. The other fields will be filled in by V4L2.
*/
void v4l2_event_queue_fh(struct v4l2_fh *fh, const struct v4l2_event *ev);
+/**
+ * v4l2_event_wake_all - Wake all filehandles.
+ *
+ * Used when unregistering a video device.
+ *
+ * @vdev: pointer to &struct video_device
+ */
+void v4l2_event_wake_all(struct video_device *vdev);
+
/**
* v4l2_event_pending - Check if an event is available
*
--
2.29.2
