/* Preventing Circular Wait by acquiring locks in order */
void *do_work_one(void *param) {
    pthread_mutex_lock(&first_mutex); // 1
    pthread_mutex_lock(&second_mutex); // 5
    /* Do work */
    pthread_mutex_unlock(&second_mutex);
    pthread_mutex_unlock(&first_mutex);
    pthread_exit(0);
}

void *do_work_two(void *param) {
    /* MUST acquire in the same order (1 then 5) to prevent deadlock */
    pthread_mutex_lock(&first_mutex); // 1
    pthread_mutex_lock(&second_mutex); // 5
    /* Do work */
    pthread_mutex_unlock(&second_mutex);
    pthread_mutex_unlock(&first_mutex);
    pthread_exit(0);
}