From: Teemu Tuominen <teemux.tuominen@xxxxxxxxx>
Add check and return POLLERR from subdev_poll() in case of no events
subscribed and wakeup once the last event subscription is removed.
This change is essentially done to add possibility to wakeup polling
with concurrent unsubscribe.
Signed-off-by: Teemu Tuominen <teemux.tuominen@xxxxxxxxx>
Move the check after calling poll_wait(). Otherwise it's possible that we go
to sleep without getting notified if the subscription went away between the
two.
Signed-off-by: Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx>
Tested-by: Teemu Tuominen <teemux.tuominen@xxxxxxxxx>
---
drivers/media/v4l2-core/v4l2-event.c | 15 +++++++++++++++
drivers/media/v4l2-core/v4l2-subdev.c | 3 +++
include/media/v4l2-event.h | 1 +
3 files changed, 19 insertions(+)
diff --git a/drivers/media/v4l2-core/v4l2-event.c b/drivers/media/v4l2-core/v4l2-event.c
index 86dcb54..b53897e 100644
--- a/drivers/media/v4l2-core/v4l2-event.c
+++ b/drivers/media/v4l2-core/v4l2-event.c
@@ -107,6 +107,19 @@ static struct v4l2_subscribed_event *v4l2_event_subscribed(
return NULL;
}
+bool v4l2_event_has_subscribed(struct v4l2_fh *fh)
+{
+ unsigned long flags;
+ bool rval;
+
+ spin_lock_irqsave(&fh->vdev->fh_lock, flags);
+ rval = !list_empty(&fh->subscribed);
+ spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
+
+ return rval;
+}
+EXPORT_SYMBOL(v4l2_event_has_subscribed);
+
static void __v4l2_event_queue_fh(struct v4l2_fh *fh, const struct v4l2_event *ev,
const struct timespec *ts)
{
@@ -299,6 +312,8 @@ int v4l2_event_unsubscribe(struct v4l2_fh *fh,
fh->navailable--;
}
list_del(&sev->list);
+ if (list_empty(&fh->subscribed))
+ wake_up_all(&fh->wait);
}
spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
diff --git a/drivers/media/v4l2-core/v4l2-subdev.c b/drivers/media/v4l2-core/v4l2-subdev.c
index 996c248..7d72389 100644
--- a/drivers/media/v4l2-core/v4l2-subdev.c
+++ b/drivers/media/v4l2-core/v4l2-subdev.c
@@ -382,6 +382,9 @@ static unsigned int subdev_poll(struct file *file, poll_table *wait)
if (v4l2_event_pending(fh))
return POLLPRI;
+ if (!v4l2_event_has_subscribed(fh))
+ return POLLERR | POLLPRI;
+
return 0;
}
diff --git a/include/media/v4l2-event.h b/include/media/v4l2-event.h
index be05d01..a9ca2b5 100644
--- a/include/media/v4l2-event.h
+++ b/include/media/v4l2-event.h
@@ -121,6 +121,7 @@ struct v4l2_subscribed_event {
int v4l2_event_dequeue(struct v4l2_fh *fh, struct v4l2_event *event,
int nonblocking);
+bool v4l2_event_has_subscribed(struct v4l2_fh *fh);
void v4l2_event_queue(struct video_device *vdev, const struct v4l2_event *ev);
void v4l2_event_queue_fh(struct v4l2_fh *fh, const struct v4l2_event *ev);
int v4l2_event_pending(struct v4l2_fh *fh);
--
1.8.3.2
--
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