Man page 9 : schedule_timeout

schedule_timeout - sleep until timeout

signed long __sched schedule_timeout(signed long  timeout );

timeout
    timeout value in jiffies

Make the current task sleep until timeout jiffies have 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 jiffies are guaranteed to pass before the routine returns. The routine will return 0

TASK_INTERRUPTIBLE - the routine may return early if a signal is delivered to the current task. In this case the remaining time in jiffies will be returned, or 0 if the timer expired in time

The current task state is guaranteed to be TASK_RUNNING when this routine returns.

Specifying a timeout value of MAX_SCHEDULE_TIMEOUT will schedule the CPU away without a bound on the timeout. In this case the return value will be MAX_SCHEDULE_TIMEOUT.

In all cases the return value is guaranteed to be non-negative.