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kernel/event_queue: Only set B_EVENT_INVALID with the lock held.

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The dequeue routine expects that if B_EVENT_INVALID is set,
it is free to delete the object. So we must only set it with
the lock held, so that by the time the dequeue routine sees it,
we will be done with the event.
This commit is contained in:
Augustin Cavalier
2023-08-04 15:19:41 -04:00
parent 45e0c33d4f
commit d8365e0f0f
1 changed files with 4 additions and 2 deletions
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src/system/kernel/events/event_queue.cpp
+4 -2
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@@ -341,7 +341,7 @@ EventQueue::_Notify(select_event* event, uint16 events)
if ((events & event->selected_events) == 0)
return;
const int32 previousEvents = atomic_or(&event->events, events);
const int32 previousEvents = atomic_or(&event->events, (events & ~B_EVENT_INVALID));
// If the event is already being deleted, we should ignore this notification.
if ((previousEvents & B_EVENT_DELETING) != 0)
@@ -362,8 +362,10 @@ EventQueue::_Notify(select_event* event, uint16 events)
// If we get B_EVENT_INVALID it means the object we were monitoring was
// deleted. The object's ID may now be reused, so we must remove it
// from the event tree.
if ((events & B_EVENT_INVALID) != 0)
if ((events & B_EVENT_INVALID) != 0) {
atomic_or(&event->events, B_EVENT_INVALID);
fEventTree.Remove(event);
}
// If it's not already queued, it's our responsibility to queue it.
if ((atomic_or(&event->events, B_EVENT_QUEUED) & B_EVENT_QUEUED) == 0) {