monitor: protect event emission
Event emission must be protected by a mutex because of access to the shared rate-limiting state, and to guard against concurrent monitor "hot-plug" by means of human-monitor-command. Reviewed-by: Luiz Capitulino <lcapitulino@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
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monitor.c
16
monitor.c
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@ -217,6 +217,9 @@ struct Monitor {
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/* QMP checker flags */
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#define QMP_ACCEPT_UNKNOWNS 1
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/* Protects mon_list, monitor_event_state. */
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static QemuMutex monitor_lock;
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static QLIST_HEAD(mon_list, Monitor) mon_list;
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static QLIST_HEAD(mon_fdsets, MonFdset) mon_fdsets;
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static int mon_refcount;
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@ -465,6 +468,7 @@ static MonitorQAPIEventState monitor_qapi_event_state[QAPI_EVENT_MAX];
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/*
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* Emits the event to every monitor instance, @event is only used for trace
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* Called with monitor_lock held.
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*/
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static void monitor_qapi_event_emit(QAPIEvent event, QObject *data)
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{
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@ -497,6 +501,7 @@ monitor_qapi_event_queue(QAPIEvent event, QDict *data, Error **errp)
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now);
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/* Rate limit of 0 indicates no throttling */
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qemu_mutex_lock(&monitor_lock);
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if (!evstate->rate) {
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monitor_qapi_event_emit(event, QOBJECT(data));
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evstate->last = now;
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@ -521,6 +526,7 @@ monitor_qapi_event_queue(QAPIEvent event, QDict *data, Error **errp)
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evstate->last = now;
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}
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}
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qemu_mutex_unlock(&monitor_lock);
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}
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/*
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@ -536,12 +542,14 @@ static void monitor_qapi_event_handler(void *opaque)
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evstate->data,
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evstate->last,
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now);
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qemu_mutex_lock(&monitor_lock);
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if (evstate->data) {
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monitor_qapi_event_emit(evstate->event, evstate->data);
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qobject_decref(evstate->data);
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evstate->data = NULL;
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}
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evstate->last = now;
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qemu_mutex_unlock(&monitor_lock);
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}
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/*
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@ -5292,6 +5300,11 @@ static void monitor_readline_flush(void *opaque)
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monitor_flush(opaque);
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}
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static void __attribute__((constructor)) monitor_lock_init(void)
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{
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qemu_mutex_init(&monitor_lock);
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}
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void monitor_init(CharDriverState *chr, int flags)
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{
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static int is_first_init = 1;
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@ -5329,7 +5342,10 @@ void monitor_init(CharDriverState *chr, int flags)
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monitor_event, mon);
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}
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qemu_mutex_lock(&monitor_lock);
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QLIST_INSERT_HEAD(&mon_list, mon, entry);
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qemu_mutex_unlock(&monitor_lock);
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if (!default_mon || (flags & MONITOR_IS_DEFAULT))
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default_mon = mon;
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}
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