Fix fr_event_user_trigger so it works over multiple calls

diff --git a/src/lib/util/event.c b/src/lib/util/event.c
index 21252acfb9902b8ea03afc14212c538119506754..367a7bf2748c8e54491105e2935dbd2b155b4c5a 100644 (file)
--- a/src/lib/util/event.c
+++ b/src/lib/util/event.c
@@ -1928,7 +1928,17 @@ int fr_event_user_trigger(fr_event_user_t *ev)
 {
        struct kevent evset;
 
-       EV_SET(&evset, (uintptr_t)ev, EVFILT_USER, 0, NOTE_TRIGGER, 0, NULL);
+       /*
+        *      The event was registered with EV_DISPATCH, which makes
+        *      kqueue auto-disable it each time it fires.  A plain
+        *      NOTE_TRIGGER on a disabled event is accepted by the kernel
+        *      but not delivered to userspace until the event is
+        *      re-enabled, so we pass EV_ENABLE alongside the trigger to
+        *      re-arm it atomically.  Without this, the second and
+        *      subsequent trigger calls would silently never wake the
+        *      consumer.
+        */
+       EV_SET(&evset, (uintptr_t)ev, EVFILT_USER, EV_ENABLE, NOTE_TRIGGER, 0, NULL);
 
        if (unlikely(kevent(ev->el->kq, &evset, 1, NULL, 0, NULL) < 0)) {
                fr_strerror_printf("Failed triggering user event - kevent %s", fr_syserror(evset.flags));