Add a monitor_destroyed global to check if monitor_cleanup() has been
already called. In this case, don't insert the new monitor in the
list, but free it instead.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
---
 monitor.c | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/monitor.c b/monitor.c
index c175cf6f0d..90b7867ed4 100644
--- a/monitor.c
+++ b/monitor.c
@@ -262,10 +262,11 @@ typedef struct QMPRequest QMPRequest;
 /* QMP checker flags */
 #define QMP_ACCEPT_UNKNOWNS 1
 
-/* Protects mon_list, monitor_qapi_event_state.  */
+/* Protects mon_list, monitor_qapi_event_state, monitor_destroyed.  */
 static QemuMutex monitor_lock;
 static GHashTable *monitor_qapi_event_state;
 static QTAILQ_HEAD(mon_list, Monitor) mon_list;
+static bool monitor_destroyed;
 
 /* Protects mon_fdsets */
 static QemuMutex mon_fdsets_lock;
@@ -4526,8 +4527,16 @@ void error_vprintf_unless_qmp(const char *fmt, va_list ap)
 static void monitor_list_append(Monitor *mon)
 {
     qemu_mutex_lock(&monitor_lock);
-    QTAILQ_INSERT_HEAD(&mon_list, mon, entry);
+    if (!monitor_destroyed) {
+        QTAILQ_INSERT_HEAD(&mon_list, mon, entry);
+        mon = NULL;
+    }
     qemu_mutex_unlock(&monitor_lock);
+
+    if (mon) {
+        monitor_data_destroy(mon);
+        g_free(mon);
+    }
 }
 
 static void monitor_qmp_setup_handlers_bh(void *opaque)
@@ -4620,6 +4629,7 @@ void monitor_cleanup(void)
 
     /* Flush output buffers and destroy monitors */
     qemu_mutex_lock(&monitor_lock);
+    monitor_destroyed = true;
     QTAILQ_FOREACH_SAFE(mon, &mon_list, entry, next) {
         QTAILQ_REMOVE(&mon_list, mon, entry);
         monitor_flush(mon);
-- 
2.19.0.271.gfe8321ec05