monitor/monitor.c

   1 /*
   2  * QEMU monitor
   3  *
   4  * Copyright (c) 2003-2004 Fabrice Bellard
   5  *
   6  * Permission is hereby granted, free of charge, to any person obtaining a copy
   7  * of this software and associated documentation files (the "Software"), to deal
   8  * in the Software without restriction, including without limitation the rights
   9  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  10  * copies of the Software, and to permit persons to whom the Software is
  11  * furnished to do so, subject to the following conditions:
  12  *
  13  * The above copyright notice and this permission notice shall be included in
  14  * all copies or substantial portions of the Software.
  15  *
  16  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  17  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  18  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
  19  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  20  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  21  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  22  * THE SOFTWARE.
  23  */
  24
  25 #include "qemu/osdep.h"
  26 #include "monitor-internal.h"
  27 #include "qapi/error.h"
  28 #include "qapi/opts-visitor.h"
  29 #include "qapi/qapi-emit-events.h"
  30 #include "qapi/qapi-visit-control.h"
  31 #include "qapi/qmp/qdict.h"
  32 #include "qemu/error-report.h"
  33 #include "qemu/option.h"
  34 #include "sysemu/qtest.h"
  35 #include "trace.h"
  36
  37 /*
  38  * To prevent flooding clients, events can be throttled. The
  39  * throttling is calculated globally, rather than per-Monitor
  40  * instance.
  41  */
  42 typedef struct MonitorQAPIEventState {
  43     QAPIEvent event;    /* Throttling state for this event type and... */
  44     QDict *data;        /* ... data, see qapi_event_throttle_equal() */
  45     QEMUTimer *timer;   /* Timer for handling delayed events */
  46     QDict *qdict;       /* Delayed event (if any) */
  47 } MonitorQAPIEventState;
  48
  49 typedef struct {
  50     int64_t rate;       /* Minimum time (in ns) between two events */
  51 } MonitorQAPIEventConf;
  52
  53 /* Shared monitor I/O thread */
  54 IOThread *mon_iothread;
  55
  56 /* Coroutine to dispatch the requests received from I/O thread */
  57 Coroutine *qmp_dispatcher_co;
  58
  59 /*
  60  * Set to true when the dispatcher coroutine should terminate.  Protected
  61  * by monitor_lock.
  62  */
  63 bool qmp_dispatcher_co_shutdown;
  64
  65 /*
  66  * Protects mon_list, monitor_qapi_event_state, coroutine_mon,
  67  * monitor_destroyed.
  68  */
  69 QemuMutex monitor_lock;
  70 static GHashTable *monitor_qapi_event_state;
  71 static GHashTable *coroutine_mon; /* Maps Coroutine* to Monitor* */
  72
  73 MonitorList mon_list;
  74 int mon_refcount;
  75 static bool monitor_destroyed;
  76
  77 Monitor *monitor_cur(void)
  78 {
  79     Monitor *mon;
  80
  81     qemu_mutex_lock(&monitor_lock);
  82     mon = g_hash_table_lookup(coroutine_mon, qemu_coroutine_self());
  83     qemu_mutex_unlock(&monitor_lock);
  84
  85     return mon;
  86 }
  87
  88 /**
  89  * Sets a new current monitor and returns the old one.
  90  *
  91  * If a non-NULL monitor is set for a coroutine, another call
  92  * resetting it to NULL is required before the coroutine terminates,
  93  * otherwise a stale entry would remain in the hash table.
  94  */
  95 Monitor *monitor_set_cur(Coroutine *co, Monitor *mon)
  96 {
  97     Monitor *old_monitor = monitor_cur();
  98
  99     qemu_mutex_lock(&monitor_lock);
 100     if (mon) {
 101         g_hash_table_replace(coroutine_mon, co, mon);
 102     } else {
 103         g_hash_table_remove(coroutine_mon, co);
 104     }
 105     qemu_mutex_unlock(&monitor_lock);
 106
 107     return old_monitor;
 108 }
 109
 110 /**
 111  * Is the current monitor, if any, a QMP monitor?
 112  */
 113 bool monitor_cur_is_qmp(void)
 114 {
 115     Monitor *cur_mon = monitor_cur();
 116
 117     return cur_mon && monitor_is_qmp(cur_mon);
 118 }
 119
 120 /**
 121  * Is @mon is using readline?
 122  * Note: not all HMP monitors use readline, e.g., gdbserver has a
 123  * non-interactive HMP monitor, so readline is not used there.
 124  */
 125 static inline bool monitor_uses_readline(const MonitorHMP *mon)
 126 {
 127     return mon->use_readline;
 128 }
 129
 130 static inline bool monitor_is_hmp_non_interactive(const Monitor *mon)
 131 {
 132     if (monitor_is_qmp(mon)) {
 133         return false;
 134     }
 135
 136     return !monitor_uses_readline(container_of(mon, MonitorHMP, common));
 137 }
 138
 139 static gboolean monitor_unblocked(void *do_not_use, GIOCondition cond,
 140                                   void *opaque)
 141 {
 142     Monitor *mon = opaque;
 143
 144     QEMU_LOCK_GUARD(&mon->mon_lock);
 145     mon->out_watch = 0;
 146     monitor_flush_locked(mon);
 147     return G_SOURCE_REMOVE;
 148 }
 149
 150 /* Caller must hold mon->mon_lock */
 151 void monitor_flush_locked(Monitor *mon)
 152 {
 153     int rc;
 154     size_t len;
 155     const char *buf;
 156
 157     if (mon->skip_flush) {
 158         return;
 159     }
 160
 161     buf = mon->outbuf->str;
 162     len = mon->outbuf->len;
 163
 164     if (len && !mon->mux_out) {
 165         rc = qemu_chr_fe_write(&mon->chr, (const uint8_t *) buf, len);
 166         if ((rc < 0 && errno != EAGAIN) || (rc == len)) {
 167             /* all flushed or error */
 168             g_string_truncate(mon->outbuf, 0);
 169             return;
 170         }
 171         if (rc > 0) {
 172             /* partial write */
 173             g_string_erase(mon->outbuf, 0, rc);
 174         }
 175         if (mon->out_watch == 0) {
 176             mon->out_watch =
 177                 qemu_chr_fe_add_watch(&mon->chr, G_IO_OUT | G_IO_HUP,
 178                                       monitor_unblocked, mon);
 179         }
 180     }
 181 }
 182
 183 void monitor_flush(Monitor *mon)
 184 {
 185     QEMU_LOCK_GUARD(&mon->mon_lock);
 186     monitor_flush_locked(mon);
 187 }
 188
 189 /* flush at every end of line */
 190 int monitor_puts_locked(Monitor *mon, const char *str)
 191 {
 192     int i;
 193     char c;
 194
 195     for (i = 0; str[i]; i++) {
 196         c = str[i];
 197         if (c == '\n') {
 198             g_string_append_c(mon->outbuf, '\r');
 199         }
 200         g_string_append_c(mon->outbuf, c);
 201         if (c == '\n') {
 202             monitor_flush_locked(mon);
 203         }
 204     }
 205
 206     return i;
 207 }
 208
 209 int monitor_puts(Monitor *mon, const char *str)
 210 {
 211     QEMU_LOCK_GUARD(&mon->mon_lock);
 212     return monitor_puts_locked(mon, str);
 213 }
 214
 215 int monitor_vprintf(Monitor *mon, const char *fmt, va_list ap)
 216 {
 217     char *buf;
 218     int n;
 219
 220     if (!mon) {
 221         return -1;
 222     }
 223
 224     if (monitor_is_qmp(mon)) {
 225         return -1;
 226     }
 227
 228     buf = g_strdup_vprintf(fmt, ap);
 229     n = monitor_puts(mon, buf);
 230     g_free(buf);
 231     return n;
 232 }
 233
 234 int monitor_printf(Monitor *mon, const char *fmt, ...)
 235 {
 236     int ret;
 237
 238     va_list ap;
 239     va_start(ap, fmt);
 240     ret = monitor_vprintf(mon, fmt, ap);
 241     va_end(ap);
 242     return ret;
 243 }
 244
 245 void monitor_printc(Monitor *mon, int c)
 246 {
 247     monitor_printf(mon, "'");
 248     switch(c) {
 249     case '\'':
 250         monitor_printf(mon, "\\'");
 251         break;
 252     case '\\':
 253         monitor_printf(mon, "\\\\");
 254         break;
 255     case '\n':
 256         monitor_printf(mon, "\\n");
 257         break;
 258     case '\r':
 259         monitor_printf(mon, "\\r");
 260         break;
 261     default:
 262         if (c >= 32 && c <= 126) {
 263             monitor_printf(mon, "%c", c);
 264         } else {
 265             monitor_printf(mon, "\\x%02x", c);
 266         }
 267         break;
 268     }
 269     monitor_printf(mon, "'");
 270 }
 271
 272 /*
 273  * Print to current monitor if we have one, else to stderr.
 274  */
 275 int error_vprintf(const char *fmt, va_list ap)
 276 {
 277     Monitor *cur_mon = monitor_cur();
 278
 279     if (cur_mon && !monitor_cur_is_qmp()) {
 280         return monitor_vprintf(cur_mon, fmt, ap);
 281     }
 282     return vfprintf(stderr, fmt, ap);
 283 }
 284
 285 int error_vprintf_unless_qmp(const char *fmt, va_list ap)
 286 {
 287     Monitor *cur_mon = monitor_cur();
 288
 289     if (!cur_mon) {
 290         return vfprintf(stderr, fmt, ap);
 291     }
 292     if (!monitor_cur_is_qmp()) {
 293         return monitor_vprintf(cur_mon, fmt, ap);
 294     }
 295     return -1;
 296 }
 297
 298 int error_printf_unless_qmp(const char *fmt, ...)
 299 {
 300     va_list ap;
 301     int ret;
 302
 303     va_start(ap, fmt);
 304     ret = error_vprintf_unless_qmp(fmt, ap);
 305     va_end(ap);
 306     return ret;
 307 }
 308
 309 static MonitorQAPIEventConf monitor_qapi_event_conf[QAPI_EVENT__MAX] = {
 310     /* Limit guest-triggerable events to 1 per second */
 311     [QAPI_EVENT_RTC_CHANGE]        = { 1000 * SCALE_MS },
 312     [QAPI_EVENT_WATCHDOG]          = { 1000 * SCALE_MS },
 313     [QAPI_EVENT_BALLOON_CHANGE]    = { 1000 * SCALE_MS },
 314     [QAPI_EVENT_QUORUM_REPORT_BAD] = { 1000 * SCALE_MS },
 315     [QAPI_EVENT_QUORUM_FAILURE]    = { 1000 * SCALE_MS },
 316     [QAPI_EVENT_VSERPORT_CHANGE]   = { 1000 * SCALE_MS },
 317     [QAPI_EVENT_MEMORY_DEVICE_SIZE_CHANGE] = { 1000 * SCALE_MS },
 318 };
 319
 320 /*
 321  * Return the clock to use for recording an event's time.
 322  * It's QEMU_CLOCK_REALTIME, except for qtests it's
 323  * QEMU_CLOCK_VIRTUAL, to support testing rate limits.
 324  * Beware: result is invalid before configure_accelerator().
 325  */
 326 static inline QEMUClockType monitor_get_event_clock(void)
 327 {
 328     return qtest_enabled() ? QEMU_CLOCK_VIRTUAL : QEMU_CLOCK_REALTIME;
 329 }
 330
 331 /*
 332  * Broadcast an event to all monitors.
 333  * @qdict is the event object.  Its member "event" must match @event.
 334  * Caller must hold monitor_lock.
 335  */
 336 static void monitor_qapi_event_emit(QAPIEvent event, QDict *qdict)
 337 {
 338     Monitor *mon;
 339     MonitorQMP *qmp_mon;
 340
 341     trace_monitor_protocol_event_emit(event, qdict);
 342     QTAILQ_FOREACH(mon, &mon_list, entry) {
 343         if (!monitor_is_qmp(mon)) {
 344             continue;
 345         }
 346
 347         qmp_mon = container_of(mon, MonitorQMP, common);
 348         if (qmp_mon->commands != &qmp_cap_negotiation_commands) {
 349             qmp_send_response(qmp_mon, qdict);
 350         }
 351     }
 352 }
 353
 354 static void monitor_qapi_event_handler(void *opaque);
 355
 356 /*
 357  * Queue a new event for emission to Monitor instances,
 358  * applying any rate limiting if required.
 359  */
 360 static void
 361 monitor_qapi_event_queue_no_reenter(QAPIEvent event, QDict *qdict)
 362 {
 363     MonitorQAPIEventConf *evconf;
 364     MonitorQAPIEventState *evstate;
 365
 366     assert(event < QAPI_EVENT__MAX);
 367     evconf = &monitor_qapi_event_conf[event];
 368     trace_monitor_protocol_event_queue(event, qdict, evconf->rate);
 369
 370     QEMU_LOCK_GUARD(&monitor_lock);
 371
 372     if (!evconf->rate) {
 373         /* Unthrottled event */
 374         monitor_qapi_event_emit(event, qdict);
 375     } else {
 376         QDict *data = qobject_to(QDict, qdict_get(qdict, "data"));
 377         MonitorQAPIEventState key = { .event = event, .data = data };
 378
 379         evstate = g_hash_table_lookup(monitor_qapi_event_state, &key);
 380         assert(!evstate || timer_pending(evstate->timer));
 381
 382         if (evstate) {
 383             /*
 384              * Timer is pending for (at least) evconf->rate ns after
 385              * last send.  Store event for sending when timer fires,
 386              * replacing a prior stored event if any.
 387              */
 388             qobject_unref(evstate->qdict);
 389             evstate->qdict = qobject_ref(qdict);
 390         } else {
 391             /*
 392              * Last send was (at least) evconf->rate ns ago.
 393              * Send immediately, and arm the timer to call
 394              * monitor_qapi_event_handler() in evconf->rate ns.  Any
 395              * events arriving before then will be delayed until then.
 396              */
 397             int64_t now = qemu_clock_get_ns(monitor_get_event_clock());
 398
 399             monitor_qapi_event_emit(event, qdict);
 400
 401             evstate = g_new(MonitorQAPIEventState, 1);
 402             evstate->event = event;
 403             evstate->data = qobject_ref(data);
 404             evstate->qdict = NULL;
 405             evstate->timer = timer_new_ns(monitor_get_event_clock(),
 406                                           monitor_qapi_event_handler,
 407                                           evstate);
 408             g_hash_table_add(monitor_qapi_event_state, evstate);
 409             timer_mod_ns(evstate->timer, now + evconf->rate);
 410         }
 411     }
 412 }
 413
 414 void qapi_event_emit(QAPIEvent event, QDict *qdict)
 415 {
 416     /*
 417      * monitor_qapi_event_queue_no_reenter() is not reentrant: it
 418      * would deadlock on monitor_lock.  Work around by queueing
 419      * events in thread-local storage.
 420      * TODO: remove this, make it re-enter safe.
 421      */
 422     typedef struct MonitorQapiEvent {
 423         QAPIEvent event;
 424         QDict *qdict;
 425         QSIMPLEQ_ENTRY(MonitorQapiEvent) entry;
 426     } MonitorQapiEvent;
 427     static __thread QSIMPLEQ_HEAD(, MonitorQapiEvent) event_queue;
 428     static __thread bool reentered;
 429     MonitorQapiEvent *ev;
 430
 431     if (!reentered) {
 432         QSIMPLEQ_INIT(&event_queue);
 433     }
 434
 435     ev = g_new(MonitorQapiEvent, 1);
 436     ev->qdict = qobject_ref(qdict);
 437     ev->event = event;
 438     QSIMPLEQ_INSERT_TAIL(&event_queue, ev, entry);
 439     if (reentered) {
 440         return;
 441     }
 442
 443     reentered = true;
 444
 445     while ((ev = QSIMPLEQ_FIRST(&event_queue)) != NULL) {
 446         QSIMPLEQ_REMOVE_HEAD(&event_queue, entry);
 447         monitor_qapi_event_queue_no_reenter(ev->event, ev->qdict);
 448         qobject_unref(ev->qdict);
 449         g_free(ev);
 450     }
 451
 452     reentered = false;
 453 }
 454
 455 /*
 456  * This function runs evconf->rate ns after sending a throttled
 457  * event.
 458  * If another event has since been stored, send it.
 459  */
 460 static void monitor_qapi_event_handler(void *opaque)
 461 {
 462     MonitorQAPIEventState *evstate = opaque;
 463     MonitorQAPIEventConf *evconf = &monitor_qapi_event_conf[evstate->event];
 464
 465     trace_monitor_protocol_event_handler(evstate->event, evstate->qdict);
 466     QEMU_LOCK_GUARD(&monitor_lock);
 467
 468     if (evstate->qdict) {
 469         int64_t now = qemu_clock_get_ns(monitor_get_event_clock());
 470
 471         monitor_qapi_event_emit(evstate->event, evstate->qdict);
 472         qobject_unref(evstate->qdict);
 473         evstate->qdict = NULL;
 474         timer_mod_ns(evstate->timer, now + evconf->rate);
 475     } else {
 476         g_hash_table_remove(monitor_qapi_event_state, evstate);
 477         qobject_unref(evstate->data);
 478         timer_free(evstate->timer);
 479         g_free(evstate);
 480     }
 481 }
 482
 483 static unsigned int qapi_event_throttle_hash(const void *key)
 484 {
 485     const MonitorQAPIEventState *evstate = key;
 486     unsigned int hash = evstate->event * 255;
 487
 488     if (evstate->event == QAPI_EVENT_VSERPORT_CHANGE) {
 489         hash += g_str_hash(qdict_get_str(evstate->data, "id"));
 490     }
 491
 492     if (evstate->event == QAPI_EVENT_QUORUM_REPORT_BAD) {
 493         hash += g_str_hash(qdict_get_str(evstate->data, "node-name"));
 494     }
 495
 496     if (evstate->event == QAPI_EVENT_MEMORY_DEVICE_SIZE_CHANGE) {
 497         hash += g_str_hash(qdict_get_str(evstate->data, "qom-path"));
 498     }
 499
 500     return hash;
 501 }
 502
 503 static gboolean qapi_event_throttle_equal(const void *a, const void *b)
 504 {
 505     const MonitorQAPIEventState *eva = a;
 506     const MonitorQAPIEventState *evb = b;
 507
 508     if (eva->event != evb->event) {
 509         return FALSE;
 510     }
 511
 512     if (eva->event == QAPI_EVENT_VSERPORT_CHANGE) {
 513         return !strcmp(qdict_get_str(eva->data, "id"),
 514                        qdict_get_str(evb->data, "id"));
 515     }
 516
 517     if (eva->event == QAPI_EVENT_QUORUM_REPORT_BAD) {
 518         return !strcmp(qdict_get_str(eva->data, "node-name"),
 519                        qdict_get_str(evb->data, "node-name"));
 520     }
 521
 522     if (eva->event == QAPI_EVENT_MEMORY_DEVICE_SIZE_CHANGE) {
 523         return !strcmp(qdict_get_str(eva->data, "qom-path"),
 524                        qdict_get_str(evb->data, "qom-path"));
 525     }
 526
 527     return TRUE;
 528 }
 529
 530 int monitor_suspend(Monitor *mon)
 531 {
 532     if (monitor_is_hmp_non_interactive(mon)) {
 533         return -ENOTTY;
 534     }
 535
 536     qatomic_inc(&mon->suspend_cnt);
 537
 538     if (mon->use_io_thread) {
 539         /*
 540          * Kick I/O thread to make sure this takes effect.  It'll be
 541          * evaluated again in prepare() of the watch object.
 542          */
 543         aio_notify(iothread_get_aio_context(mon_iothread));
 544     }
 545
 546     trace_monitor_suspend(mon, 1);
 547     return 0;
 548 }
 549
 550 static void monitor_accept_input(void *opaque)
 551 {
 552     Monitor *mon = opaque;
 553
 554     qemu_mutex_lock(&mon->mon_lock);
 555     if (!monitor_is_qmp(mon) && mon->reset_seen) {
 556         MonitorHMP *hmp_mon = container_of(mon, MonitorHMP, common);
 557         assert(hmp_mon->rs);
 558         readline_restart(hmp_mon->rs);
 559         qemu_mutex_unlock(&mon->mon_lock);
 560         readline_show_prompt(hmp_mon->rs);
 561     } else {
 562         qemu_mutex_unlock(&mon->mon_lock);
 563     }
 564
 565     qemu_chr_fe_accept_input(&mon->chr);
 566 }
 567
 568 void monitor_resume(Monitor *mon)
 569 {
 570     if (monitor_is_hmp_non_interactive(mon)) {
 571         return;
 572     }
 573
 574     if (qatomic_dec_fetch(&mon->suspend_cnt) == 0) {
 575         AioContext *ctx;
 576
 577         if (mon->use_io_thread) {
 578             ctx = iothread_get_aio_context(mon_iothread);
 579         } else {
 580             ctx = qemu_get_aio_context();
 581         }
 582
 583         aio_bh_schedule_oneshot(ctx, monitor_accept_input, mon);
 584     }
 585
 586     trace_monitor_suspend(mon, -1);
 587 }
 588
 589 int monitor_can_read(void *opaque)
 590 {
 591     Monitor *mon = opaque;
 592
 593     return !qatomic_read(&mon->suspend_cnt);
 594 }
 595
 596 void monitor_list_append(Monitor *mon)
 597 {
 598     qemu_mutex_lock(&monitor_lock);
 599     /*
 600      * This prevents inserting new monitors during monitor_cleanup().
 601      * A cleaner solution would involve the main thread telling other
 602      * threads to terminate, waiting for their termination.
 603      */
 604     if (!monitor_destroyed) {
 605         QTAILQ_INSERT_HEAD(&mon_list, mon, entry);
 606         mon = NULL;
 607     }
 608     qemu_mutex_unlock(&monitor_lock);
 609
 610     if (mon) {
 611         monitor_data_destroy(mon);
 612         g_free(mon);
 613     }
 614 }
 615
 616 static void monitor_iothread_init(void)
 617 {
 618     mon_iothread = iothread_create("mon_iothread", &error_abort);
 619 }
 620
 621 void monitor_data_init(Monitor *mon, bool is_qmp, bool skip_flush,
 622                        bool use_io_thread)
 623 {
 624     if (use_io_thread && !mon_iothread) {
 625         monitor_iothread_init();
 626     }
 627     qemu_mutex_init(&mon->mon_lock);
 628     mon->is_qmp = is_qmp;
 629     mon->outbuf = g_string_new(NULL);
 630     mon->skip_flush = skip_flush;
 631     mon->use_io_thread = use_io_thread;
 632 }
 633
 634 void monitor_data_destroy(Monitor *mon)
 635 {
 636     g_free(mon->mon_cpu_path);
 637     qemu_chr_fe_deinit(&mon->chr, false);
 638     if (monitor_is_qmp(mon)) {
 639         monitor_data_destroy_qmp(container_of(mon, MonitorQMP, common));
 640     } else {
 641         readline_free(container_of(mon, MonitorHMP, common)->rs);
 642     }
 643     g_string_free(mon->outbuf, true);
 644     qemu_mutex_destroy(&mon->mon_lock);
 645 }
 646
 647 void monitor_cleanup(void)
 648 {
 649     /*
 650      * The dispatcher needs to stop before destroying the monitor and
 651      * the I/O thread.
 652      *
 653      * We need to poll both qemu_aio_context and iohandler_ctx to make
 654      * sure that the dispatcher coroutine keeps making progress and
 655      * eventually terminates.  qemu_aio_context is automatically
 656      * polled by calling AIO_WAIT_WHILE_UNLOCKED on it, but we must poll
 657      * iohandler_ctx manually.
 658      *
 659      * Letting the iothread continue while shutting down the dispatcher
 660      * means that new requests may still be coming in. This is okay,
 661      * we'll just leave them in the queue without sending a response
 662      * and monitor_data_destroy() will free them.
 663      */
 664     WITH_QEMU_LOCK_GUARD(&monitor_lock) {
 665         qmp_dispatcher_co_shutdown = true;
 666     }
 667     qmp_dispatcher_co_wake();
 668
 669     AIO_WAIT_WHILE_UNLOCKED(NULL,
 670                    (aio_poll(iohandler_get_aio_context(), false),
 671                     qatomic_read(&qmp_dispatcher_co)));
 672
 673     /*
 674      * We need to explicitly stop the I/O thread (but not destroy it),
 675      * clean up the monitor resources, then destroy the I/O thread since
 676      * we need to unregister from chardev below in
 677      * monitor_data_destroy(), and chardev is not thread-safe yet
 678      */
 679     if (mon_iothread) {
 680         iothread_stop(mon_iothread);
 681     }
 682
 683     /* Flush output buffers and destroy monitors */
 684     qemu_mutex_lock(&monitor_lock);
 685     monitor_destroyed = true;
 686     while (!QTAILQ_EMPTY(&mon_list)) {
 687         Monitor *mon = QTAILQ_FIRST(&mon_list);
 688         QTAILQ_REMOVE(&mon_list, mon, entry);
 689         /* Permit QAPI event emission from character frontend release */
 690         qemu_mutex_unlock(&monitor_lock);
 691         monitor_flush(mon);
 692         monitor_data_destroy(mon);
 693         qemu_mutex_lock(&monitor_lock);
 694         g_free(mon);
 695     }
 696     qemu_mutex_unlock(&monitor_lock);
 697
 698     if (mon_iothread) {
 699         iothread_destroy(mon_iothread);
 700         mon_iothread = NULL;
 701     }
 702 }
 703
 704 static void monitor_qapi_event_init(void)
 705 {
 706     monitor_qapi_event_state = g_hash_table_new(qapi_event_throttle_hash,
 707                                                 qapi_event_throttle_equal);
 708 }
 709
 710 void monitor_init_globals(void)
 711 {
 712     monitor_qapi_event_init();
 713     qemu_mutex_init(&monitor_lock);
 714     coroutine_mon = g_hash_table_new(NULL, NULL);
 715
 716     /*
 717      * The dispatcher BH must run in the main loop thread, since we
 718      * have commands assuming that context.  It would be nice to get
 719      * rid of those assumptions.
 720      */
 721     qmp_dispatcher_co = qemu_coroutine_create(monitor_qmp_dispatcher_co, NULL);
 722     aio_co_schedule(iohandler_get_aio_context(), qmp_dispatcher_co);
 723 }
 724
 725 int monitor_init(MonitorOptions *opts, bool allow_hmp, Error **errp)
 726 {
 727     ERRP_GUARD();
 728     Chardev *chr;
 729
 730     chr = qemu_chr_find(opts->chardev);
 731     if (chr == NULL) {
 732         error_setg(errp, "chardev \"%s\" not found", opts->chardev);
 733         return -1;
 734     }
 735
 736     if (!opts->has_mode) {
 737         opts->mode = allow_hmp ? MONITOR_MODE_READLINE : MONITOR_MODE_CONTROL;
 738     }
 739
 740     switch (opts->mode) {
 741     case MONITOR_MODE_CONTROL:
 742         monitor_init_qmp(chr, opts->pretty, errp);
 743         break;
 744     case MONITOR_MODE_READLINE:
 745         if (!allow_hmp) {
 746             error_setg(errp, "Only QMP is supported");
 747             return -1;
 748         }
 749         if (opts->pretty) {
 750             error_setg(errp, "'pretty' is not compatible with HMP monitors");
 751             return -1;
 752         }
 753         monitor_init_hmp(chr, true, errp);
 754         break;
 755     default:
 756         g_assert_not_reached();
 757     }
 758
 759     return *errp ? -1 : 0;
 760 }
 761
 762 int monitor_init_opts(QemuOpts *opts, Error **errp)
 763 {
 764     Visitor *v;
 765     MonitorOptions *options;
 766     int ret;
 767
 768     v = opts_visitor_new(opts);
 769     visit_type_MonitorOptions(v, NULL, &options, errp);
 770     visit_free(v);
 771     if (!options) {
 772         return -1;
 773     }
 774
 775     ret = monitor_init(options, true, errp);
 776     qapi_free_MonitorOptions(options);
 777     return ret;
 778 }
 779
 780 QemuOptsList qemu_mon_opts = {
 781     .name = "mon",
 782     .implied_opt_name = "chardev",
 783     .head = QTAILQ_HEAD_INITIALIZER(qemu_mon_opts.head),
 784     .desc = {
 785         {
 786             .name = "mode",
 787             .type = QEMU_OPT_STRING,
 788         },{
 789             .name = "chardev",
 790             .type = QEMU_OPT_STRING,
 791         },{
 792             .name = "pretty",
 793             .type = QEMU_OPT_BOOL,
 794         },
 795         { /* end of list */ }
 796     },
 797 };