Commit b2a06aec authored by Sakari Ailus's avatar Sakari Ailus Committed by Mauro Carvalho Chehab
Browse files

[media] v4l: Only get module if it's different than the driver for v4l2_dev 



When the sub-device is registered, increment the use count of the sub-device
owner only if it's different from the owner of the driver for the media
device. This avoids increasing the use count by the module itself and thus
making it possible to unload it when it's not in use.

Signed-off-by: default avatarSakari Ailus <sakari.ailus@linux.intel.com>
Acked-by: default avatarLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: default avatarMauro Carvalho Chehab <m.chehab@samsung.com>
parent 85de721c

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

+15 −3
Original line number Diff line number Diff line
@@ -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;
@@ -192,6 +202,7 @@ error_unregister: 
	if (sd->internal_ops && sd->internal_ops->unregistered)

		sd->internal_ops->unregistered(sd);

error_module:

	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);

	if (!sd->owner_v4l2_dev)

		module_put(sd->owner);

}

EXPORT_SYMBOL_GPL(v4l2_device_unregister_subdev);

include/media/v4l2-subdev.h

+1 −0
Original line number Diff line number Diff line
@@ -584,6 +584,7 @@ struct v4l2_subdev { 
#endif

	struct list_head list;

	struct module *owner;

	bool owner_v4l2_dev;

	u32 flags;

	struct v4l2_device *v4l2_dev;

	const struct v4l2_subdev_ops *ops;

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