At some point in the past, the OPEN event was changed to be issued from a bottom half. This creates a small window whereas a data callback registered in init may be invoked before the OPEN event has been issued.
This is reproducible with: echo "{'execute': 'qmp_capabilities'}" | qemu-system-x86_64 -M none -qmp stdio We can fix this for the monitor by moving the parser initialization to init. The remaining state that is set in OPEN appears harmless. Reported-by: Daniel Berrange <berra...@redhat.com> Signed-off-by: Anthony Liguori <aligu...@us.ibm.com> --- monitor.c | 4 +++- 1 files changed, 3 insertions(+), 1 deletions(-) diff --git a/monitor.c b/monitor.c index 480f583..b188582 100644 --- a/monitor.c +++ b/monitor.c @@ -4832,7 +4832,6 @@ static void monitor_control_event(void *opaque, int event) switch (event) { case CHR_EVENT_OPENED: mon->mc->command_mode = 0; - json_message_parser_init(&mon->mc->parser, handle_qmp_command); data = get_qmp_greeting(); monitor_json_emitter(mon, data); qobject_decref(data); @@ -4840,6 +4839,7 @@ static void monitor_control_event(void *opaque, int event) break; case CHR_EVENT_CLOSED: json_message_parser_destroy(&mon->mc->parser); + json_message_parser_init(&mon->mc->parser, handle_qmp_command); mon_refcount--; monitor_fdsets_cleanup(); break; @@ -4951,6 +4951,8 @@ void monitor_init(CharDriverState *chr, int flags) monitor_event, mon); } + json_message_parser_init(&mon->mc->parser, handle_qmp_command); + QLIST_INSERT_HEAD(&mon_list, mon, entry); if (!default_mon || (flags & MONITOR_IS_DEFAULT)) default_mon = mon; -- 1.7.5.4