C++ CLOCK_DISPATCH函数代码示例

/*
 * This will restart clock_nanosleep. This is required only by
 * compat_clock_nanosleep_restart for now.
 */
long
clock_nanosleep_restart(struct restart_block *restart_block)
{
	clockid_t which_clock = restart_block->arg0;

	return CLOCK_DISPATCH(which_clock, nsleep_restart,
			      (restart_block));
}

SYSCALL_DEFINE2(clock_settime, const clockid_t, which_clock,
		const struct timespec __user *, tp)
{
	struct timespec new_tp;

	if (invalid_clockid(which_clock))
		return -EINVAL;
	if (copy_from_user(&new_tp, tp, sizeof (*tp)))
		return -EFAULT;

	return CLOCK_DISPATCH(which_clock, clock_set, (which_clock, &new_tp));
}

SYSCALL_DEFINE4(clock_nanosleep, const clockid_t, which_clock, int, flags,
		const struct timespec __user *, rqtp,
		struct timespec __user *, rmtp)
{
	struct timespec t;

	if (invalid_clockid(which_clock))
		return -EINVAL;

	if (copy_from_user(&t, rqtp, sizeof (struct timespec)))
		return -EFAULT;

	if (!timespec_valid(&t))
		return -EINVAL;

	return CLOCK_DISPATCH(which_clock, nsleep,
			      (which_clock, flags, &t, rmtp));
}

static inline int timer_delete_hook(struct k_itimer *timer)
{
	return CLOCK_DISPATCH(timer->it_clock, timer_del, (timer));
}

SYSCALL_DEFINE3(timer_create, const clockid_t, which_clock,
		struct sigevent __user *, timer_event_spec,
		timer_t __user *, created_timer_id)
{
	struct k_itimer *new_timer;
	int error, new_timer_id;
	sigevent_t event;
	int it_id_set = IT_ID_NOT_SET;

	if (invalid_clockid(which_clock))
		return -EINVAL;

	new_timer = alloc_posix_timer();
	if (unlikely(!new_timer))
		return -EAGAIN;

	spin_lock_init(&new_timer->it_lock);
 retry:
	if (unlikely(!idr_pre_get(&posix_timers_id, GFP_KERNEL))) {
		error = -EAGAIN;
		goto out;
	}
	spin_lock_irq(&idr_lock);
	error = idr_get_new(&posix_timers_id, new_timer, &new_timer_id);
	spin_unlock_irq(&idr_lock);
	if (error) {
		if (error == -EAGAIN)
			goto retry;
		/*
		 * Weird looking, but we return EAGAIN if the IDR is
		 * full (proper POSIX return value for this)
		 */
		error = -EAGAIN;
		goto out;
	}

	it_id_set = IT_ID_SET;
	new_timer->it_id = (timer_t) new_timer_id;
	new_timer->it_clock = which_clock;
	new_timer->it_overrun = -1;
	error = CLOCK_DISPATCH(which_clock, timer_create, (new_timer));
	if (error)
		goto out;

	/*
	 * return the timer_id now.  The next step is hard to
	 * back out if there is an error.
	 */
	if (copy_to_user(created_timer_id,
			 &new_timer_id, sizeof (new_timer_id))) {
		error = -EFAULT;
		goto out;
	}
	if (timer_event_spec) {
		if (copy_from_user(&event, timer_event_spec, sizeof (event))) {
			error = -EFAULT;
			goto out;
		}
		rcu_read_lock();
		new_timer->it_pid = get_pid(good_sigevent(&event));
		rcu_read_unlock();
		if (!new_timer->it_pid) {
			error = -EINVAL;
			goto out;
		}
	} else {
		event.sigev_notify = SIGEV_SIGNAL;
		event.sigev_signo = SIGALRM;
		event.sigev_value.sival_int = new_timer->it_id;
		new_timer->it_pid = get_pid(task_tgid(current));
	}

	new_timer->it_sigev_notify     = event.sigev_notify;
	new_timer->sigq->info.si_signo = event.sigev_signo;
	new_timer->sigq->info.si_value = event.sigev_value;
	new_timer->sigq->info.si_tid   = new_timer->it_id;
	new_timer->sigq->info.si_code  = SI_TIMER;

	spin_lock_irq(&current->sighand->siglock);
	new_timer->it_signal = current->signal;
	list_add(&new_timer->list, &current->signal->posix_timers);
	spin_unlock_irq(&current->sighand->siglock);

	return 0;
 	/*
	 * In the case of the timer belonging to another task, after
	 * the task is unlocked, the timer is owned by the other task
	 * and may cease to exist at any time.  Don't use or modify
	 * new_timer after the unlock call.
	 */
out:
	release_posix_timer(new_timer, it_id_set);
	return error;
}