static void destruct_tty_driver(struct kref *kref)
{
	struct tty_driver *driver = container_of(kref, struct tty_driver, kref);
	int i;
	struct ktermios *tp;

	if (driver->flags & TTY_DRIVER_INSTALLED) {
		/*
		 * Free the termios and termios_locked structures because
		 * we don't want to get memory leaks when modular tty
		 * drivers are removed from the kernel.
		 */
		for (i = 0; i < driver->num; i++) {
			tp = driver->termios[i];
			if (tp) {
				driver->termios[i] = NULL;
				kfree(tp);
			}
			if (!(driver->flags & TTY_DRIVER_DYNAMIC_DEV))
				tty_unregister_device(driver, i);
		}
		proc_tty_unregister_driver(driver);
		if (driver->flags & TTY_DRIVER_DYNAMIC_ALLOC)
			cdev_del(driver->cdevs[0]);
	}
	kfree(driver->cdevs);
	kfree(driver->ports);
	kfree(driver->termios);
	kfree(driver->ttys);
	kfree(driver);
}

The product contains a concurrent code sequence that requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence operating concurrently.