spin_lock_thread
err = pthread_create(&thread_id[i], NULL, &spin_lock_thread, &prog_fd);
&spin_lock_thread, &prog_fd)))
err = pthread_create(&thread_id[i], NULL, &spin_lock_thread, &prog_fd);
err = pthread_create(&thread_id[i], NULL, &spin_lock_thread, &prog_fd);
&spin_lock_thread, &prog_fd);