diff options
| -rw-r--r-- | monitor.c | 201 |
1 files changed, 178 insertions, 23 deletions
@@ -172,6 +172,13 @@ typedef struct { */ QmpCommandList *commands; bool qmp_caps[QMP_CAPABILITY__MAX]; + /* + * Protects qmp request/response queue. Please take monitor_lock + * first when used together. + */ + QemuMutex qmp_queue_lock; + /* Input queue that holds all the parsed QMP requests */ + GQueue *qmp_requests; } MonitorQMP; /* @@ -218,6 +225,8 @@ struct Monitor { /* Let's add monitor global variables to this struct. */ static struct { IOThread *mon_iothread; + /* Bottom half to dispatch the requests received from IO thread */ + QEMUBH *qmp_dispatcher_bh; } mon_global; /* QMP checker flags */ @@ -600,11 +609,13 @@ static void monitor_data_init(Monitor *mon, bool skip_flush, { memset(mon, 0, sizeof(Monitor)); qemu_mutex_init(&mon->out_lock); + qemu_mutex_init(&mon->qmp.qmp_queue_lock); mon->outbuf = qstring_new(); /* Use *mon_cmds by default. */ mon->cmd_table = mon_cmds; mon->skip_flush = skip_flush; mon->use_io_thr = use_io_thr; + mon->qmp.qmp_requests = g_queue_new(); } static void monitor_data_destroy(Monitor *mon) @@ -617,6 +628,8 @@ static void monitor_data_destroy(Monitor *mon) readline_free(mon->rs); QDECREF(mon->outbuf); qemu_mutex_destroy(&mon->out_lock); + qemu_mutex_destroy(&mon->qmp.qmp_queue_lock); + g_queue_free(mon->qmp.qmp_requests); } char *qmp_human_monitor_command(const char *command_line, bool has_cpu_index, @@ -1059,6 +1072,16 @@ static void monitor_init_qmp_commands(void) qmp_marshal_qmp_capabilities, QCO_NO_OPTIONS); } +static bool qmp_cap_enabled(Monitor *mon, QMPCapability cap) +{ + return mon->qmp.qmp_caps[cap]; +} + +static bool qmp_oob_enabled(Monitor *mon) +{ + return qmp_cap_enabled(mon, QMP_CAPABILITY_OOB); +} + static void qmp_caps_check(Monitor *mon, QMPCapabilityList *list, Error **errp) { @@ -3869,30 +3892,39 @@ static void monitor_qmp_respond(Monitor *mon, QObject *rsp, qobject_decref(rsp); } -static void handle_qmp_command(JSONMessageParser *parser, GQueue *tokens) +struct QMPRequest { + /* Owner of the request */ + Monitor *mon; + /* "id" field of the request */ + QObject *id; + /* Request object to be handled */ + QObject *req; + /* + * Whether we need to resume the monitor afterward. This flag is + * used to emulate the old QMP server behavior that the current + * command must be completed before execution of the next one. + */ + bool need_resume; +}; +typedef struct QMPRequest QMPRequest; + +/* + * Dispatch one single QMP request. The function will free the req_obj + * and objects inside it before return. + */ +static void monitor_qmp_dispatch_one(QMPRequest *req_obj) { - QObject *req, *rsp = NULL, *id = NULL; + Monitor *mon, *old_mon; + QObject *req, *rsp = NULL, *id; QDict *qdict = NULL; - MonitorQMP *mon_qmp = container_of(parser, MonitorQMP, parser); - Monitor *old_mon, *mon = container_of(mon_qmp, Monitor, qmp); - - Error *err = NULL; + bool need_resume; - req = json_parser_parse_err(tokens, NULL, &err); - if (!req && !err) { - /* json_parser_parse_err() sucks: can fail without setting @err */ - error_setg(&err, QERR_JSON_PARSING); - } - if (err) { - goto err_out; - } + req = req_obj->req; + mon = req_obj->mon; + id = req_obj->id; + need_resume = req_obj->need_resume; - qdict = qobject_to(QDict, req); - if (qdict) { - id = qdict_get(qdict, "id"); - qobject_incref(id); - qdict_del(qdict, "id"); - } /* else will fail qmp_dispatch() */ + g_free(req_obj); if (trace_event_get_state_backends(TRACE_HANDLE_QMP_COMMAND)) { QString *req_json = qobject_to_json(req); @@ -3903,7 +3935,7 @@ static void handle_qmp_command(JSONMessageParser *parser, GQueue *tokens) old_mon = cur_mon; cur_mon = mon; - rsp = qmp_dispatch(cur_mon->qmp.commands, req); + rsp = qmp_dispatch(mon->qmp.commands, req); cur_mon = old_mon; @@ -3919,12 +3951,122 @@ static void handle_qmp_command(JSONMessageParser *parser, GQueue *tokens) } } -err_out: - monitor_qmp_respond(mon, rsp, err, id); + /* Respond if necessary */ + monitor_qmp_respond(mon, rsp, NULL, id); + + /* This pairs with the monitor_suspend() in handle_qmp_command(). */ + if (need_resume) { + monitor_resume(mon); + } qobject_decref(req); } +/* + * Pop one QMP request from monitor queues, return NULL if not found. + * We are using round-robin fashion to pop the request, to avoid + * processing commands only on a very busy monitor. To achieve that, + * when we process one request on a specific monitor, we put that + * monitor to the end of mon_list queue. + */ +static QMPRequest *monitor_qmp_requests_pop_one(void) +{ + QMPRequest *req_obj = NULL; + Monitor *mon; + + qemu_mutex_lock(&monitor_lock); + + QTAILQ_FOREACH(mon, &mon_list, entry) { + qemu_mutex_lock(&mon->qmp.qmp_queue_lock); + req_obj = g_queue_pop_head(mon->qmp.qmp_requests); + qemu_mutex_unlock(&mon->qmp.qmp_queue_lock); + if (req_obj) { + break; + } + } + + if (req_obj) { + /* + * We found one request on the monitor. Degrade this monitor's + * priority to lowest by re-inserting it to end of queue. + */ + QTAILQ_REMOVE(&mon_list, mon, entry); + QTAILQ_INSERT_TAIL(&mon_list, mon, entry); + } + + qemu_mutex_unlock(&monitor_lock); + + return req_obj; +} + +static void monitor_qmp_bh_dispatcher(void *data) +{ + QMPRequest *req_obj = monitor_qmp_requests_pop_one(); + + if (req_obj) { + monitor_qmp_dispatch_one(req_obj); + /* Reschedule instead of looping so the main loop stays responsive */ + qemu_bh_schedule(mon_global.qmp_dispatcher_bh); + } +} + +static void handle_qmp_command(JSONMessageParser *parser, GQueue *tokens) +{ + QObject *req, *id = NULL; + QDict *qdict = NULL; + MonitorQMP *mon_qmp = container_of(parser, MonitorQMP, parser); + Monitor *mon = container_of(mon_qmp, Monitor, qmp); + Error *err = NULL; + QMPRequest *req_obj; + + req = json_parser_parse_err(tokens, NULL, &err); + if (!req && !err) { + /* json_parser_parse_err() sucks: can fail without setting @err */ + error_setg(&err, QERR_JSON_PARSING); + } + if (err) { + monitor_qmp_respond(mon, NULL, err, NULL); + qobject_decref(req); + return; + } + + qdict = qobject_to(QDict, req); + if (qdict) { + id = qdict_get(qdict, "id"); + qobject_incref(id); + qdict_del(qdict, "id"); + } /* else will fail qmp_dispatch() */ + + req_obj = g_new0(QMPRequest, 1); + req_obj->mon = mon; + req_obj->id = id; + req_obj->req = req; + req_obj->need_resume = false; + + /* + * If OOB is not enabled on the current monitor, we'll emulate the + * old behavior that we won't process the current monitor any more + * until it has responded. This helps make sure that as long as + * OOB is not enabled, the server will never drop any command. + */ + if (!qmp_oob_enabled(mon)) { + monitor_suspend(mon); + req_obj->need_resume = true; + } + + /* + * Put the request to the end of queue so that requests will be + * handled in time order. Ownership for req_obj, req, id, + * etc. will be delivered to the handler side. + */ + qemu_mutex_lock(&mon->qmp.qmp_queue_lock); + g_queue_push_tail(mon->qmp.qmp_requests, req_obj); + qemu_mutex_unlock(&mon->qmp.qmp_queue_lock); + + /* Kick the dispatcher routine */ + qemu_bh_schedule(mon_global.qmp_dispatcher_bh); +} + static void monitor_qmp_read(void *opaque, const uint8_t *buf, int size) { Monitor *mon = opaque; @@ -4137,6 +4279,15 @@ static void monitor_iothread_init(void) { mon_global.mon_iothread = iothread_create("mon_iothread", &error_abort); + + /* + * This MUST be on main loop thread since we have commands that + * have assumption to be run on main loop thread. It would be + * nice that one day we can remove this assumption in the future. + */ + mon_global.qmp_dispatcher_bh = aio_bh_new(qemu_get_aio_context(), + monitor_qmp_bh_dispatcher, + NULL); } void monitor_init_globals(void) @@ -4288,6 +4439,10 @@ void monitor_cleanup(void) } qemu_mutex_unlock(&monitor_lock); + /* QEMUBHs needs to be deleted before destroying the IOThread. */ + qemu_bh_delete(mon_global.qmp_dispatcher_bh); + mon_global.qmp_dispatcher_bh = NULL; + iothread_destroy(mon_global.mon_iothread); mon_global.mon_iothread = NULL; } |