In the Linux kernel, the following vulnerability has been resolved: schhtb: make htbqlennotify() idempotent htbqlennotify() always deactivates the HTB class and in fact could trigger a warning if it is already deactivated. Therefore, it is not idempotent and not friendly to its callers, like fqcodeldequeue(). Let's make it idempotent to ease qdisctreereducebacklog() callers' life.