void
recursive_lock_release(pTHX_ recursive_lock_t *lock)
{
    MUTEX_LOCK(&lock->mutex);
    if (lock->owner == aTHX) {
        if (--lock->locks == 0) {
            lock->owner = NULL;
            COND_SIGNAL(&lock->cond);
        }
    }
    MUTEX_UNLOCK(&lock->mutex);
}