media: v4l: async: Return async sub-devices to subnotifier list

When an async notifier is unregistered, the async sub-devices in the
notifier's done list will disappear with the notifier. However this is
currently also done to the sub-notifiers that remain registered. Their
sub-devices only need to be unbound while the async sub-devices themselves
need to be returned to the sub-notifier's waiting list. Do this now.

Fixes: 2cab00bb ("media: v4l: async: Allow binding notifiers to sub-devices")
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>

drivers/media/v4l2-core/v4l2-async.c

@@ -416,7 +416,8 @@ static void v4l2_async_cleanup(struct v4l2_subdev *sd)
 
 /* Unbind all sub-devices in the notifier tree. */
 static void
-v4l2_async_nf_unbind_all_subdevs(struct v4l2_async_notifier *notifier)
+v4l2_async_nf_unbind_all_subdevs(struct v4l2_async_notifier *notifier,
+				 bool readd)
 {
 	struct v4l2_subdev *sd, *tmp;
 
@@ -425,9 +426,11 @@ v4l2_async_nf_unbind_all_subdevs(struct v4l2_async_notifier *notifier)
 			v4l2_async_find_subdev_notifier(sd);
 
 		if (subdev_notifier)
-			v4l2_async_nf_unbind_all_subdevs(subdev_notifier);
+			v4l2_async_nf_unbind_all_subdevs(subdev_notifier, true);
 
 		v4l2_async_nf_call_unbind(notifier, sd, sd->asd);
+		if (readd)
+			list_add_tail(&sd->asd->list, &notifier->waiting);
 		v4l2_async_cleanup(sd);
 
 		list_move(&sd->async_list, &subdev_list);
@@ -559,7 +562,7 @@ static int __v4l2_async_nf_register(struct v4l2_async_notifier *notifier)
 	/*
 	 * On failure, unbind all sub-devices registered through this notifier.
 	 */
-	v4l2_async_nf_unbind_all_subdevs(notifier);
+	v4l2_async_nf_unbind_all_subdevs(notifier, false);
 
 err_unlock:
 	mutex_unlock(&list_lock);
@@ -609,7 +612,7 @@ __v4l2_async_nf_unregister(struct v4l2_async_notifier *notifier)
 	if (!notifier || (!notifier->v4l2_dev && !notifier->sd))
 		return;
 
-	v4l2_async_nf_unbind_all_subdevs(notifier);
+	v4l2_async_nf_unbind_all_subdevs(notifier, false);
 
 	notifier->sd = NULL;
 	notifier->v4l2_dev = NULL;
@@ -807,7 +810,7 @@ int v4l2_async_register_subdev(struct v4l2_subdev *sd)
 	 */
 	subdev_notifier = v4l2_async_find_subdev_notifier(sd);
 	if (subdev_notifier)
-		v4l2_async_nf_unbind_all_subdevs(subdev_notifier);
+		v4l2_async_nf_unbind_all_subdevs(subdev_notifier, false);
 
 	if (sd->asd)
 		v4l2_async_nf_call_unbind(notifier, sd, sd->asd);