__unregister_chrdev_region
kfree(__unregister_chrdev_region(MAJOR(n), MINOR(n), next - n));
kfree(__unregister_chrdev_region(cd->major, baseminor, count));
kfree(__unregister_chrdev_region(MAJOR(n), MINOR(n), next - n));
cd = __unregister_chrdev_region(major, baseminor, count);