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base: avoid deadlock and page fault

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Fixes #3830
This commit is contained in:
Alexander Boettcher 2020-07-24 13:12:02 +02:00 committed by Norman Feske
parent de7d4a5523
commit 60106ac2c8
3 changed files with 37 additions and 18 deletions
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3
repos/base/include/timer/timeout.h
View File

@ -171,7 +171,8 @@ class Genode::Timeout : private Noncopyable
Mutex _dispatch_mutex { };
Raw _raw { };
int _active { 0 };
short _active { 0 };
bool _delete { false };
Alarm *_next { nullptr };
Alarm_timeout_scheduler *_scheduler { nullptr };

4
repos/base/include/timer_session/connection.h
View File

@ -76,6 +76,8 @@ struct Timer::Periodic_timeout : private Genode::Noncopyable
{
_timeout.schedule_periodic(duration, _handler);
}
~Periodic_timeout() { _timeout.discard(); }
};
@ -121,6 +123,8 @@ class Timer::One_shot_timeout : private Genode::Noncopyable
Handler_method method)
: _timeout(timeout_scheduler), _handler(object, method) { }
~One_shot_timeout() { _timeout.discard(); }
void schedule(Microseconds duration) {
_timeout.schedule_one_shot(duration, _handler); }

48
repos/base/src/lib/timeout/timeout.cc
View File

@ -236,24 +236,30 @@ Timeout::Alarm *Alarm_timeout_scheduler::_alarm_get_pending_alarm()
{
Mutex::Guard mutex_guard(_mutex);
if (!_active_head || !_active_head->_raw.is_pending_at(_now, _now_period)) {
return nullptr; }
do {
if (!_active_head || !_active_head->_raw.is_pending_at(_now, _now_period)) {
return nullptr; }
/* remove alarm from head of the list */
Alarm *pending_alarm = _active_head;
_active_head = _active_head->_next;
/* remove alarm from head of the list */
Alarm *pending_alarm = _active_head;
_active_head = _active_head->_next;
/*
* Acquire dispatch mutex to defer destruction until the call of '_on_alarm'
* is finished
*/
pending_alarm->_dispatch_mutex.acquire();
/*
* Acquire dispatch mutex to defer destruction until the call of '_on_alarm'
* is finished
*/
pending_alarm->_dispatch_mutex.acquire();
/* reset alarm object */
pending_alarm->_next = nullptr;
pending_alarm->_active--;
/* reset alarm object */
pending_alarm->_next = nullptr;
pending_alarm->_active--;
return pending_alarm;
if (pending_alarm->_delete) {
pending_alarm->_dispatch_mutex.release();
continue;
}
return pending_alarm;
} while (true);
}
@ -399,11 +405,19 @@ void Alarm_timeout_scheduler::_alarm_discard(Alarm *alarm)
* is finished, '_alarm_get_pending_alarm' would proceed with operating on
* a dangling pointer.
*/
Mutex::Guard alarm_list_guard(_mutex);
if (alarm) {
{
/* inform that this object is going to be deleted */
Mutex::Guard alarm_guard(alarm->_dispatch_mutex);
alarm->_delete = true;
}
{
Mutex::Guard alarm_list_guard(_mutex);
_alarm_unsynchronized_dequeue(alarm);
}
/* get anyone using this out of '_alarm_get_pending_alarm'() finally */
Mutex::Guard alarm_guard(alarm->_dispatch_mutex);
_alarm_unsynchronized_dequeue(alarm);
}
}