Merge tag 'v3.16-rc5' into next/fixes-non-critical

Linux 3.16-rc5

1 files changed, 15 insertions, 3 deletions

diff --git a/drivers/media/v4l2-core/v4l2-device.c b/drivers/media/v4l2-core/v4l2-device.c
index 02d1b632711..015f92aab44 100644
--- a/drivers/media/v4l2-core/v4l2-device.c
+++ b/drivers/media/v4l2-core/v4l2-device.c
@@ -158,7 +158,17 @@ int v4l2_device_register_subdev(struct v4l2_device *v4l2_dev,
 	/* Warn if we apparently re-register a subdev */
 	WARN_ON(sd->v4l2_dev != NULL);
 
-	if (!try_module_get(sd->owner))
+	/*
+	 * The reason to acquire the module here is to avoid unloading
+	 * a module of sub-device which is registered to a media
+	 * device. To make it possible to unload modules for media
+	 * devices that also register sub-devices, do not
+	 * try_module_get() such sub-device owners.
+	 */
+	sd->owner_v4l2_dev = v4l2_dev->dev && v4l2_dev->dev->driver &&
+		sd->owner == v4l2_dev->dev->driver->owner;
+
+	if (!sd->owner_v4l2_dev && !try_module_get(sd->owner))
 		return -ENODEV;
 
 	sd->v4l2_dev = v4l2_dev;
@@ -192,7 +202,8 @@ error_unregister:
 	if (sd->internal_ops && sd->internal_ops->unregistered)
 		sd->internal_ops->unregistered(sd);
 error_module:
-	module_put(sd->owner);
+	if (!sd->owner_v4l2_dev)
+		module_put(sd->owner);
 	sd->v4l2_dev = NULL;
 	return err;
 }
@@ -280,6 +291,7 @@ void v4l2_device_unregister_subdev(struct v4l2_subdev *sd)
 	}
 #endif
 	video_unregister_device(sd->devnode);
-	module_put(sd->owner);
+	if (!sd->owner_v4l2_dev)
+		module_put(sd->owner);
 }
 EXPORT_SYMBOL_GPL(v4l2_device_unregister_subdev);