schedule_hrtimeout — sleep until timeout
| int __sched schedule_hrtimeout ( | ktime_t * expires, | 
| const enum hrtimer_mode mode ); | 
   Make the current task sleep until the given expiry time has
   elapsed. The routine will return immediately unless
   the current task state has been set (see set_current_state).
   
You can set the task state as follows -
   TASK_UNINTERRUPTIBLE - at least timeout time is guaranteed to
   pass before the routine returns.
   
   TASK_INTERRUPTIBLE - the routine may return early if a signal is
   delivered to the current task.
   
The current task state is guaranteed to be TASK_RUNNING when this routine returns.
Returns 0 when the timer has expired otherwise -EINTR