linux_add_to_sleepqueue
ret = linux_add_to_sleepqueue(wchan, task, "woken",
ret = linux_add_to_sleepqueue(task, task, "wevent", timeout,
ret = linux_add_to_sleepqueue(task, task, "sched", timeout,
ret = linux_add_to_sleepqueue(wchan, task, "wbit", timeout,
ret = linux_add_to_sleepqueue(wchan, task, "watomic", 0, state);