monitor_cleanup() is one of the last things main() calls before it
returns. In the following patch, monitor_cleanup() will release the
monitor_lock during flushing. There may be pending commands to insert
new monitors, which would modify the mon_list during iteration, and
the clean-up could thus miss those new insertions.
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.lur...@redhat.com>
---
monitor.c | 19 +++++++++++++++++--
1 file changed, 17 insertions(+), 2 deletions(-)
diff --git a/monitor.c b/monitor.c
index 25cf4223e8..f0256bdec5 100644
--- a/monitor.c
+++ b/monitor.c
@@ -263,10 +263,11 @@ 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;
@@ -4538,8 +4539,21 @@ 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);
+ /*
+ * This prevents inserting new monitors during monitor_cleanup().
+ * A cleaner solution would involve the main thread telling other
+ * threads to terminate, waiting for their termination.
+ */
+ 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)
@@ -4635,6 +4649,7 @@ 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);
--
2.20.0.rc1
