qemu-timer.c

   1 /*
   2  * QEMU System Emulator
   3  *
   4  * Copyright (c) 2003-2008 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/main-loop.h"
  26 #include "qemu/timer.h"
  27
  28 #ifdef CONFIG_POSIX
  29 #include <pthread.h>
  30 #endif
  31
  32 #ifdef CONFIG_PPOLL
  33 #include <poll.h>
  34 #endif
  35
  36 #ifdef CONFIG_PRCTL_PR_SET_TIMERSLACK
  37 #include <sys/prctl.h>
  38 #endif
  39
  40 /***********************************************************/
  41 /* timers */
  42
  43 typedef struct QEMUClock {
  44     /* We rely on BQL to protect the timerlists */
  45     QLIST_HEAD(, QEMUTimerList) timerlists;
  46
  47     NotifierList reset_notifiers;
  48     int64_t last;
  49
  50     QEMUClockType type;
  51     bool enabled;
  52 } QEMUClock;
  53
  54 QEMUTimerListGroup main_loop_tlg;
  55 static QEMUClock qemu_clocks[QEMU_CLOCK_MAX];
  56
  57 /* A QEMUTimerList is a list of timers attached to a clock. More
  58  * than one QEMUTimerList can be attached to each clock, for instance
  59  * used by different AioContexts / threads. Each clock also has
  60  * a list of the QEMUTimerLists associated with it, in order that
  61  * reenabling the clock can call all the notifiers.
  62  */
  63
  64 struct QEMUTimerList {
  65     QEMUClock *clock;
  66     QemuMutex active_timers_lock;
  67     QEMUTimer *active_timers;
  68     QLIST_ENTRY(QEMUTimerList) list;
  69     QEMUTimerListNotifyCB *notify_cb;
  70     void *notify_opaque;
  71
  72     /* lightweight method to mark the end of timerlist's running */
  73     QemuEvent timers_done_ev;
  74 };
  75
  76 /**
  77  * qemu_clock_ptr:
  78  * @type: type of clock
  79  *
  80  * Translate a clock type into a pointer to QEMUClock object.
  81  *
  82  * Returns: a pointer to the QEMUClock object
  83  */
  84 static inline QEMUClock *qemu_clock_ptr(QEMUClockType type)
  85 {
  86     return &qemu_clocks[type];
  87 }
  88
  89 static bool timer_expired_ns(QEMUTimer *timer_head, int64_t current_time)
  90 {
  91     return timer_head && (timer_head->expire_time <= current_time);
  92 }
  93
  94 QEMUTimerList *timerlist_new(QEMUClockType type,
  95                              QEMUTimerListNotifyCB *cb,
  96                              void *opaque)
  97 {
  98     QEMUTimerList *timer_list;
  99     QEMUClock *clock = qemu_clock_ptr(type);
 100
 101     timer_list = g_malloc0(sizeof(QEMUTimerList));
 102     qemu_event_init(&timer_list->timers_done_ev, true);
 103     timer_list->clock = clock;
 104     timer_list->notify_cb = cb;
 105     timer_list->notify_opaque = opaque;
 106     qemu_mutex_init(&timer_list->active_timers_lock);
 107     QLIST_INSERT_HEAD(&clock->timerlists, timer_list, list);
 108     return timer_list;
 109 }
 110
 111 void timerlist_free(QEMUTimerList *timer_list)
 112 {
 113     assert(!timerlist_has_timers(timer_list));
 114     if (timer_list->clock) {
 115         QLIST_REMOVE(timer_list, list);
 116     }
 117     qemu_mutex_destroy(&timer_list->active_timers_lock);
 118     g_free(timer_list);
 119 }
 120
 121 static void qemu_clock_init(QEMUClockType type)
 122 {
 123     QEMUClock *clock = qemu_clock_ptr(type);
 124
 125     /* Assert that the clock of type TYPE has not been initialized yet. */
 126     assert(main_loop_tlg.tl[type] == NULL);
 127
 128     clock->type = type;
 129     clock->enabled = true;
 130     clock->last = INT64_MIN;
 131     QLIST_INIT(&clock->timerlists);
 132     notifier_list_init(&clock->reset_notifiers);
 133     main_loop_tlg.tl[type] = timerlist_new(type, NULL, NULL);
 134 }
 135
 136 bool qemu_clock_use_for_deadline(QEMUClockType type)
 137 {
 138     return !(use_icount && (type == QEMU_CLOCK_VIRTUAL));
 139 }
 140
 141 void qemu_clock_notify(QEMUClockType type)
 142 {
 143     QEMUTimerList *timer_list;
 144     QEMUClock *clock = qemu_clock_ptr(type);
 145     QLIST_FOREACH(timer_list, &clock->timerlists, list) {
 146         timerlist_notify(timer_list);
 147     }
 148 }
 149
 150 /* Disabling the clock will wait for related timerlists to stop
 151  * executing qemu_run_timers.  Thus, this functions should not
 152  * be used from the callback of a timer that is based on @clock.
 153  * Doing so would cause a deadlock.
 154  *
 155  * Caller should hold BQL.
 156  */
 157 void qemu_clock_enable(QEMUClockType type, bool enabled)
 158 {
 159     QEMUClock *clock = qemu_clock_ptr(type);
 160     QEMUTimerList *tl;
 161     bool old = clock->enabled;
 162     clock->enabled = enabled;
 163     if (enabled && !old) {
 164         qemu_clock_notify(type);
 165     } else if (!enabled && old) {
 166         QLIST_FOREACH(tl, &clock->timerlists, list) {
 167             qemu_event_wait(&tl->timers_done_ev);
 168         }
 169     }
 170 }
 171
 172 bool timerlist_has_timers(QEMUTimerList *timer_list)
 173 {
 174     return !!timer_list->active_timers;
 175 }
 176
 177 bool qemu_clock_has_timers(QEMUClockType type)
 178 {
 179     return timerlist_has_timers(
 180         main_loop_tlg.tl[type]);
 181 }
 182
 183 bool timerlist_expired(QEMUTimerList *timer_list)
 184 {
 185     int64_t expire_time;
 186
 187     qemu_mutex_lock(&timer_list->active_timers_lock);
 188     if (!timer_list->active_timers) {
 189         qemu_mutex_unlock(&timer_list->active_timers_lock);
 190         return false;
 191     }
 192     expire_time = timer_list->active_timers->expire_time;
 193     qemu_mutex_unlock(&timer_list->active_timers_lock);
 194
 195     return expire_time < qemu_clock_get_ns(timer_list->clock->type);
 196 }
 197
 198 bool qemu_clock_expired(QEMUClockType type)
 199 {
 200     return timerlist_expired(
 201         main_loop_tlg.tl[type]);
 202 }
 203
 204 /*
 205  * As above, but return -1 for no deadline, and do not cap to 2^32
 206  * as we know the result is always positive.
 207  */
 208
 209 int64_t timerlist_deadline_ns(QEMUTimerList *timer_list)
 210 {
 211     int64_t delta;
 212     int64_t expire_time;
 213
 214     if (!timer_list->clock->enabled) {
 215         return -1;
 216     }
 217
 218     /* The active timers list may be modified before the caller uses our return
 219      * value but ->notify_cb() is called when the deadline changes.  Therefore
 220      * the caller should notice the change and there is no race condition.
 221      */
 222     qemu_mutex_lock(&timer_list->active_timers_lock);
 223     if (!timer_list->active_timers) {
 224         qemu_mutex_unlock(&timer_list->active_timers_lock);
 225         return -1;
 226     }
 227     expire_time = timer_list->active_timers->expire_time;
 228     qemu_mutex_unlock(&timer_list->active_timers_lock);
 229
 230     delta = expire_time - qemu_clock_get_ns(timer_list->clock->type);
 231
 232     if (delta <= 0) {
 233         return 0;
 234     }
 235
 236     return delta;
 237 }
 238
 239 /* Calculate the soonest deadline across all timerlists attached
 240  * to the clock. This is used for the icount timeout so we
 241  * ignore whether or not the clock should be used in deadline
 242  * calculations.
 243  */
 244 int64_t qemu_clock_deadline_ns_all(QEMUClockType type)
 245 {
 246     int64_t deadline = -1;
 247     QEMUTimerList *timer_list;
 248     QEMUClock *clock = qemu_clock_ptr(type);
 249     QLIST_FOREACH(timer_list, &clock->timerlists, list) {
 250         deadline = qemu_soonest_timeout(deadline,
 251                                         timerlist_deadline_ns(timer_list));
 252     }
 253     return deadline;
 254 }
 255
 256 QEMUClockType timerlist_get_clock(QEMUTimerList *timer_list)
 257 {
 258     return timer_list->clock->type;
 259 }
 260
 261 QEMUTimerList *qemu_clock_get_main_loop_timerlist(QEMUClockType type)
 262 {
 263     return main_loop_tlg.tl[type];
 264 }
 265
 266 void timerlist_notify(QEMUTimerList *timer_list)
 267 {
 268     if (timer_list->notify_cb) {
 269         timer_list->notify_cb(timer_list->notify_opaque);
 270     } else {
 271         qemu_notify_event();
 272     }
 273 }
 274
 275 /* Transition function to convert a nanosecond timeout to ms
 276  * This is used where a system does not support ppoll
 277  */
 278 int qemu_timeout_ns_to_ms(int64_t ns)
 279 {
 280     int64_t ms;
 281     if (ns < 0) {
 282         return -1;
 283     }
 284
 285     if (!ns) {
 286         return 0;
 287     }
 288
 289     /* Always round up, because it's better to wait too long than to wait too
 290      * little and effectively busy-wait
 291      */
 292     ms = (ns + SCALE_MS - 1) / SCALE_MS;
 293
 294     /* To avoid overflow problems, limit this to 2^31, i.e. approx 25 days */
 295     if (ms > (int64_t) INT32_MAX) {
 296         ms = INT32_MAX;
 297     }
 298
 299     return (int) ms;
 300 }
 301
 302
 303 /* qemu implementation of g_poll which uses a nanosecond timeout but is
 304  * otherwise identical to g_poll
 305  */
 306 int qemu_poll_ns(GPollFD *fds, guint nfds, int64_t timeout)
 307 {
 308 #ifdef CONFIG_PPOLL
 309     if (timeout < 0) {
 310         return ppoll((struct pollfd *)fds, nfds, NULL, NULL);
 311     } else {
 312         struct timespec ts;
 313         int64_t tvsec = timeout / 1000000000LL;
 314         /* Avoid possibly overflowing and specifying a negative number of
 315          * seconds, which would turn a very long timeout into a busy-wait.
 316          */
 317         if (tvsec > (int64_t)INT32_MAX) {
 318             tvsec = INT32_MAX;
 319         }
 320         ts.tv_sec = tvsec;
 321         ts.tv_nsec = timeout % 1000000000LL;
 322         return ppoll((struct pollfd *)fds, nfds, &ts, NULL);
 323     }
 324 #else
 325     return g_poll(fds, nfds, qemu_timeout_ns_to_ms(timeout));
 326 #endif
 327 }
 328
 329
 330 void timer_init_tl(QEMUTimer *ts,
 331                    QEMUTimerList *timer_list, int scale,
 332                    QEMUTimerCB *cb, void *opaque)
 333 {
 334     ts->timer_list = timer_list;
 335     ts->cb = cb;
 336     ts->opaque = opaque;
 337     ts->scale = scale;
 338     ts->expire_time = -1;
 339 }
 340
 341 void timer_deinit(QEMUTimer *ts)
 342 {
 343     assert(ts->expire_time == -1);
 344     ts->timer_list = NULL;
 345 }
 346
 347 void timer_free(QEMUTimer *ts)
 348 {
 349     g_free(ts);
 350 }
 351
 352 static void timer_del_locked(QEMUTimerList *timer_list, QEMUTimer *ts)
 353 {
 354     QEMUTimer **pt, *t;
 355
 356     ts->expire_time = -1;
 357     pt = &timer_list->active_timers;
 358     for(;;) {
 359         t = *pt;
 360         if (!t)
 361             break;
 362         if (t == ts) {
 363             *pt = t->next;
 364             break;
 365         }
 366         pt = &t->next;
 367     }
 368 }
 369
 370 static bool timer_mod_ns_locked(QEMUTimerList *timer_list,
 371                                 QEMUTimer *ts, int64_t expire_time)
 372 {
 373     QEMUTimer **pt, *t;
 374
 375     /* add the timer in the sorted list */
 376     pt = &timer_list->active_timers;
 377     for (;;) {
 378         t = *pt;
 379         if (!timer_expired_ns(t, expire_time)) {
 380             break;
 381         }
 382         pt = &t->next;
 383     }
 384     ts->expire_time = MAX(expire_time, 0);
 385     ts->next = *pt;
 386     *pt = ts;
 387
 388     return pt == &timer_list->active_timers;
 389 }
 390
 391 static void timerlist_rearm(QEMUTimerList *timer_list)
 392 {
 393     /* Interrupt execution to force deadline recalculation.  */
 394     qemu_clock_warp(timer_list->clock->type);
 395     timerlist_notify(timer_list);
 396 }
 397
 398 /* stop a timer, but do not dealloc it */
 399 void timer_del(QEMUTimer *ts)
 400 {
 401     QEMUTimerList *timer_list = ts->timer_list;
 402
 403     if (timer_list) {
 404         qemu_mutex_lock(&timer_list->active_timers_lock);
 405         timer_del_locked(timer_list, ts);
 406         qemu_mutex_unlock(&timer_list->active_timers_lock);
 407     }
 408 }
 409
 410 /* modify the current timer so that it will be fired when current_time
 411    >= expire_time. The corresponding callback will be called. */
 412 void timer_mod_ns(QEMUTimer *ts, int64_t expire_time)
 413 {
 414     QEMUTimerList *timer_list = ts->timer_list;
 415     bool rearm;
 416
 417     qemu_mutex_lock(&timer_list->active_timers_lock);
 418     timer_del_locked(timer_list, ts);
 419     rearm = timer_mod_ns_locked(timer_list, ts, expire_time);
 420     qemu_mutex_unlock(&timer_list->active_timers_lock);
 421
 422     if (rearm) {
 423         timerlist_rearm(timer_list);
 424     }
 425 }
 426
 427 /* modify the current timer so that it will be fired when current_time
 428    >= expire_time or the current deadline, whichever comes earlier.
 429    The corresponding callback will be called. */
 430 void timer_mod_anticipate_ns(QEMUTimer *ts, int64_t expire_time)
 431 {
 432     QEMUTimerList *timer_list = ts->timer_list;
 433     bool rearm;
 434
 435     qemu_mutex_lock(&timer_list->active_timers_lock);
 436     if (ts->expire_time == -1 || ts->expire_time > expire_time) {
 437         if (ts->expire_time != -1) {
 438             timer_del_locked(timer_list, ts);
 439         }
 440         rearm = timer_mod_ns_locked(timer_list, ts, expire_time);
 441     } else {
 442         rearm = false;
 443     }
 444     qemu_mutex_unlock(&timer_list->active_timers_lock);
 445
 446     if (rearm) {
 447         timerlist_rearm(timer_list);
 448     }
 449 }
 450
 451 void timer_mod(QEMUTimer *ts, int64_t expire_time)
 452 {
 453     timer_mod_ns(ts, expire_time * ts->scale);
 454 }
 455
 456 void timer_mod_anticipate(QEMUTimer *ts, int64_t expire_time)
 457 {
 458     timer_mod_anticipate_ns(ts, expire_time * ts->scale);
 459 }
 460
 461 bool timer_pending(QEMUTimer *ts)
 462 {
 463     return ts->expire_time >= 0;
 464 }
 465
 466 bool timer_expired(QEMUTimer *timer_head, int64_t current_time)
 467 {
 468     return timer_expired_ns(timer_head, current_time * timer_head->scale);
 469 }
 470
 471 bool timerlist_run_timers(QEMUTimerList *timer_list)
 472 {
 473     QEMUTimer *ts;
 474     int64_t current_time;
 475     bool progress = false;
 476     QEMUTimerCB *cb;
 477     void *opaque;
 478
 479     qemu_event_reset(&timer_list->timers_done_ev);
 480     if (!timer_list->clock->enabled) {
 481         goto out;
 482     }
 483
 484     current_time = qemu_clock_get_ns(timer_list->clock->type);
 485     for(;;) {
 486         qemu_mutex_lock(&timer_list->active_timers_lock);
 487         ts = timer_list->active_timers;
 488         if (!timer_expired_ns(ts, current_time)) {
 489             qemu_mutex_unlock(&timer_list->active_timers_lock);
 490             break;
 491         }
 492
 493         /* remove timer from the list before calling the callback */
 494         timer_list->active_timers = ts->next;
 495         ts->next = NULL;
 496         ts->expire_time = -1;
 497         cb = ts->cb;
 498         opaque = ts->opaque;
 499         qemu_mutex_unlock(&timer_list->active_timers_lock);
 500
 501         /* run the callback (the timer list can be modified) */
 502         cb(opaque);
 503         progress = true;
 504     }
 505
 506 out:
 507     qemu_event_set(&timer_list->timers_done_ev);
 508     return progress;
 509 }
 510
 511 bool qemu_clock_run_timers(QEMUClockType type)
 512 {
 513     return timerlist_run_timers(main_loop_tlg.tl[type]);
 514 }
 515
 516 void timerlistgroup_init(QEMUTimerListGroup *tlg,
 517                          QEMUTimerListNotifyCB *cb, void *opaque)
 518 {
 519     QEMUClockType type;
 520     for (type = 0; type < QEMU_CLOCK_MAX; type++) {
 521         tlg->tl[type] = timerlist_new(type, cb, opaque);
 522     }
 523 }
 524
 525 void timerlistgroup_deinit(QEMUTimerListGroup *tlg)
 526 {
 527     QEMUClockType type;
 528     for (type = 0; type < QEMU_CLOCK_MAX; type++) {
 529         timerlist_free(tlg->tl[type]);
 530     }
 531 }
 532
 533 bool timerlistgroup_run_timers(QEMUTimerListGroup *tlg)
 534 {
 535     QEMUClockType type;
 536     bool progress = false;
 537     for (type = 0; type < QEMU_CLOCK_MAX; type++) {
 538         progress |= timerlist_run_timers(tlg->tl[type]);
 539     }
 540     return progress;
 541 }
 542
 543 int64_t timerlistgroup_deadline_ns(QEMUTimerListGroup *tlg)
 544 {
 545     int64_t deadline = -1;
 546     QEMUClockType type;
 547     for (type = 0; type < QEMU_CLOCK_MAX; type++) {
 548         if (qemu_clock_use_for_deadline(tlg->tl[type]->clock->type)) {
 549             deadline = qemu_soonest_timeout(deadline,
 550                                             timerlist_deadline_ns(
 551                                                 tlg->tl[type]));
 552         }
 553     }
 554     return deadline;
 555 }
 556
 557 int64_t qemu_clock_get_ns(QEMUClockType type)
 558 {
 559     int64_t now, last;
 560     QEMUClock *clock = qemu_clock_ptr(type);
 561
 562     switch (type) {
 563     case QEMU_CLOCK_REALTIME:
 564         return get_clock();
 565     default:
 566     case QEMU_CLOCK_VIRTUAL:
 567         if (use_icount) {
 568             return cpu_get_icount();
 569         } else {
 570             return cpu_get_clock();
 571         }
 572     case QEMU_CLOCK_HOST:
 573         now = get_clock_realtime();
 574         last = clock->last;
 575         clock->last = now;
 576         if (now < last || now > (last + get_max_clock_jump())) {
 577             notifier_list_notify(&clock->reset_notifiers, &now);
 578         }
 579         return now;
 580     case QEMU_CLOCK_VIRTUAL_RT:
 581         return cpu_get_clock();
 582     }
 583 }
 584
 585 void qemu_clock_register_reset_notifier(QEMUClockType type,
 586                                         Notifier *notifier)
 587 {
 588     QEMUClock *clock = qemu_clock_ptr(type);
 589     notifier_list_add(&clock->reset_notifiers, notifier);
 590 }
 591
 592 void qemu_clock_unregister_reset_notifier(QEMUClockType type,
 593                                           Notifier *notifier)
 594 {
 595     notifier_remove(notifier);
 596 }
 597
 598 void init_clocks(void)
 599 {
 600     QEMUClockType type;
 601     for (type = 0; type < QEMU_CLOCK_MAX; type++) {
 602         qemu_clock_init(type);
 603     }
 604
 605 #ifdef CONFIG_PRCTL_PR_SET_TIMERSLACK
 606     prctl(PR_SET_TIMERSLACK, 1, 0, 0, 0);
 607 #endif
 608 }
 609
 610 uint64_t timer_expire_time_ns(QEMUTimer *ts)
 611 {
 612     return timer_pending(ts) ? ts->expire_time : -1;
 613 }
 614
 615 bool qemu_clock_run_all_timers(void)
 616 {
 617     bool progress = false;
 618     QEMUClockType type;
 619
 620     for (type = 0; type < QEMU_CLOCK_MAX; type++) {
 621         progress |= qemu_clock_run_timers(type);
 622     }
 623
 624     return progress;
 625 }