Date: Tue, 12 Dec 2017 17:29:35 +0000 (UTC) From: Mark Johnston <markj@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r326798 - head/sys/geom/mirror Message-ID: <201712121729.vBCHTZdV075014@repo.freebsd.org>
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Author: markj Date: Tue Dec 12 17:29:34 2017 New Revision: 326798 URL: https://svnweb.freebsd.org/changeset/base/326798 Log: Address a possible lost wakeup for gmirror events. g_mirror_event_send() acquires the I/O queue lock to deliver a wakeup to the worker thread, and this is done after enqueuing the event. So it's sufficient to check the event queue before atomically releasing the queue lock and going to sleep. MFC after: 1 week Sponsored by: Dell EMC Isilon Modified: head/sys/geom/mirror/g_mirror.c Modified: head/sys/geom/mirror/g_mirror.c ============================================================================== --- head/sys/geom/mirror/g_mirror.c Tue Dec 12 17:25:25 2017 (r326797) +++ head/sys/geom/mirror/g_mirror.c Tue Dec 12 17:29:34 2017 (r326798) @@ -1945,16 +1945,9 @@ g_mirror_worker(void *arg) continue; } } + if (g_mirror_event_first(sc) != NULL) + continue; sx_xunlock(&sc->sc_lock); - /* - * XXX: We can miss an event here, because an event - * can be added without sx-device-lock and without - * mtx-queue-lock. Maybe I should just stop using - * dedicated mutex for events synchronization and - * stick with the queue lock? - * The event will hang here until next I/O request - * or next event is received. - */ MSLEEP(sc, &sc->sc_queue_mtx, PRIBIO | PDROP, "m:w1", timeout * hz); sx_xlock(&sc->sc_lock);
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