fix th .no_wait callback called multi times issue. - #209
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mitchellh
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Feb 27, 2026
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We need a test to validate this. I also like your more detailed comment in your commit:
Fix use-after-free in kqueue no_wait mode
When tick() is called with wait=0 (no_wait mode), it would exit
immediately after processing events without submitting pending
EV_DELETE changes to kqueue. This caused a use-after-free bug:
1. Events complete and callbacks return .disarm
2. DELETEs are queued in local events[] array
3. Completions are marked .dead and recycled
4. tick() exits with wait==0 before submitting DELETEs
5. kqueue still has stale registrations with dead udata pointers
6. Later events (like EOF) arrive with corrupted pointers
Fix: Only exit early if both wait==0 AND changes==0. This ensures
we loop back to submit pending DELETEs via kevent_syscall with
zero timeout before exiting, properly cleaning up kqueue state.
bryanjeal added a commit
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Jun 27, 2026
…xt in submit Bug mitchellh#209: kqueue tick(0) EV_DELETE flush - Changed early exit condition from 'if (wait == 0) break' to 'if (wait == 0 and changes == 0) break' so pending EV_DELETE kevent changes from the event-processing loop are flushed before tick(0) returns. Bug mitchellh#170: rearm state correction - When a non-kqueue completion (close, shutdown, threadpool fallback) returns .rearm, set flags.state to .adding before pushing to the submissions queue. Previously .dead state caused submit() to route through stop_completion (cancel) instead of start() (resubmit). Issue mitchellh#169: defensive next-pointer clear in submit() - Explicitly clear c.next before push to completions queue when processing kevent-returned events in submit(). This prevents an assertion failure if a completion is present in multiple queues concurrently (race condition).
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