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sys/event: fix race in event_wait_multi()

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We need to clear `event->next` while IRQs are still disabled to
avoid another thread from calling `event_cancel()` just in-between.
This commit is contained in:
Marian Buschsieweke 2024-12-16 20:05:19 +01:00
parent 4044c854f2
commit c5ff57c59c
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GPG Key ID: 758BD52517F79C41
1 changed files with 10 additions and 8 deletions
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18
sys/event/event.c
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@ -90,7 +90,7 @@ event_t *event_wait_multi(event_queue_t *queues, size_t n_queues)
assert(queues && n_queues);
event_t *result = NULL;
do {
while (1) {
unsigned state = irq_disable();
for (size_t i = 0; i < n_queues; i++) {
assert(queues[i].waiter);
@ -100,14 +100,16 @@ event_t *event_wait_multi(event_queue_t *queues, size_t n_queues)
break;
}
}
irq_restore(state);
if (result == NULL) {
thread_flags_wait_any(THREAD_FLAG_EVENT);
}
} while (result == NULL);
result->list_node.next = NULL;
return result;
if (result != NULL) {
result->list_node.next = NULL;
irq_restore(state);
return result;
}
irq_restore(state);
thread_flags_wait_any(THREAD_FLAG_EVENT);
}
}
#if IS_USED(MODULE_XTIMER) || IS_USED(MODULE_ZTIMER)