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fix: don't clear wait_set triggered flag without holding condition_mutex #1

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Merged
karmanyaahm merged 1 commit into from
Aug 11, 2026
Merged

fix: don't clear wait_set triggered flag without holding condition_mutex #1

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13 changes: 9 additions & 4 deletions rmw_zenoh_cpp/src/rmw_zenoh.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -2110,10 +2110,15 @@ check_and_attach_condition(
}
}

// No conditions are available. Set the triggered flag of the wait_set to false.
// Note that wait_set_data->condition_mutex has been locked before calling
// check_and_attach_condition. So it's safe to modify the wait_set_data triggered flag.
wait_set_data->triggered = false;
// No conditions are available.
//
// Do NOT clear wait_set_data->triggered here. Since #1005/#1015, rmw_wait() no longer
// holds condition_mutex while calling check_and_attach_condition(), so this write races
// with the notifier paths (e.g. SubscriptionData::add_new_message()) which set
// triggered = true under that mutex. Losing such a wakeup parks rmw_wait() forever.
//
// The reset is also redundant: rmw_wait() sets triggered = false under condition_mutex
// immediately before calling this function.

return false;
}
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