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timeout: fix outdated time in alarm scheduler 

If we add an absolute timeout to the back-end alarm-scheduler we must first
call 'handle' at the scheduler to update its internal time value.
Otherwise, it might happen that we add a timeout who's deadline is so big that
it normally belongs to the next time-counter period but the scheduler thinks
that it belongs to the current period as its time is older than the one used
to calculate the deadline.

Ref #2490
This commit is contained in:
Martin Stein 2017-09-12 14:26:45 +02:00 committed by Christian Helmuth
parent 2633ff8661
commit 8fd914c6ab
1 changed files with 9 additions and 3 deletions
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12
repos/os/src/lib/timeout/timeout.cc
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@ -102,9 +102,13 @@ void Alarm_timeout_scheduler::_enable()
void Alarm_timeout_scheduler::_schedule_one_shot(Timeout &timeout,
Microseconds duration)
{
_alarm_scheduler.schedule_absolute(
&timeout._alarm,
_time_source.curr_time().trunc_to_plain_us().value + duration.value);
unsigned long const curr_time_us =
_time_source.curr_time().trunc_to_plain_us().value;
/* ensure that the schedulers time is up-to-date before adding a timeout */
_alarm_scheduler.handle(curr_time_us);
_alarm_scheduler.schedule_absolute(&timeout._alarm,
curr_time_us + duration.value);
if (_alarm_scheduler.head_timeout(&timeout._alarm)) {
_time_source.schedule_timeout(Microseconds(0), *this); }
@ -114,8 +118,10 @@ void Alarm_timeout_scheduler::_schedule_one_shot(Timeout &timeout,
void Alarm_timeout_scheduler::_schedule_periodic(Timeout &timeout,
Microseconds duration)
{
/* ensure that the schedulers time is up-to-date before adding a timeout */
_alarm_scheduler.handle(_time_source.curr_time().trunc_to_plain_us().value);
_alarm_scheduler.schedule(&timeout._alarm, duration.value);
if (_alarm_scheduler.head_timeout(&timeout._alarm)) {
_time_source.schedule_timeout(Microseconds(0), *this); }
}