qemu

qemu-timer.c (18809B)

---

 /*
  * QEMU System Emulator
  *
  * Copyright (c) 2003-2008 Fabrice Bellard
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal
  * in the Software without restriction, including without limitation the rights
  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  * copies of the Software, and to permit persons to whom the Software is
  * furnished to do so, subject to the following conditions:
  *
  * The above copyright notice and this permission notice shall be included in
  * all copies or substantial portions of the Software.
  *
  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  * THE SOFTWARE.
  */
 
 #include "qemu/osdep.h"
 #include "qemu/main-loop.h"
 #include "qemu/timer.h"
 #include "qemu/lockable.h"
 #include "sysemu/cpu-timers.h"
 #include "sysemu/replay.h"
 #include "sysemu/cpus.h"
 
 #ifdef CONFIG_POSIX
 #include <pthread.h>
 #endif
 
 #ifdef CONFIG_PPOLL
 #include <poll.h>
 #endif
 
 #ifdef CONFIG_PRCTL_PR_SET_TIMERSLACK
 #include <sys/prctl.h>
 #endif
 
 /***********************************************************/
 /* timers */
 
 typedef struct QEMUClock {
     /* We rely on BQL to protect the timerlists */
     QLIST_HEAD(, QEMUTimerList) timerlists;
 
     QEMUClockType type;
     bool enabled;
 } QEMUClock;
 
 QEMUTimerListGroup main_loop_tlg;
 static QEMUClock qemu_clocks[QEMU_CLOCK_MAX];
 
 /* A QEMUTimerList is a list of timers attached to a clock. More
  * than one QEMUTimerList can be attached to each clock, for instance
  * used by different AioContexts / threads. Each clock also has
  * a list of the QEMUTimerLists associated with it, in order that
  * reenabling the clock can call all the notifiers.
  */
 
 struct QEMUTimerList {
     QEMUClock *clock;
     QemuMutex active_timers_lock;
     QEMUTimer *active_timers;
     QLIST_ENTRY(QEMUTimerList) list;
     QEMUTimerListNotifyCB *notify_cb;
     void *notify_opaque;
 
     /* lightweight method to mark the end of timerlist's running */
     QemuEvent timers_done_ev;
 };
 
 /**
  * qemu_clock_ptr:
  * @type: type of clock
  *
  * Translate a clock type into a pointer to QEMUClock object.
  *
  * Returns: a pointer to the QEMUClock object
  */
 static inline QEMUClock *qemu_clock_ptr(QEMUClockType type)
 {
     return &qemu_clocks[type];
 }
 
 static bool timer_expired_ns(QEMUTimer *timer_head, int64_t current_time)
 {
     return timer_head && (timer_head->expire_time <= current_time);
 }
 
 QEMUTimerList *timerlist_new(QEMUClockType type,
                              QEMUTimerListNotifyCB *cb,
                              void *opaque)
 {
     QEMUTimerList *timer_list;
     QEMUClock *clock = qemu_clock_ptr(type);
 
     timer_list = g_new0(QEMUTimerList, 1);
     qemu_event_init(&timer_list->timers_done_ev, true);
     timer_list->clock = clock;
     timer_list->notify_cb = cb;
     timer_list->notify_opaque = opaque;
     qemu_mutex_init(&timer_list->active_timers_lock);
     QLIST_INSERT_HEAD(&clock->timerlists, timer_list, list);
     return timer_list;
 }
 
 void timerlist_free(QEMUTimerList *timer_list)
 {
     assert(!timerlist_has_timers(timer_list));
     if (timer_list->clock) {
         QLIST_REMOVE(timer_list, list);
     }
     qemu_mutex_destroy(&timer_list->active_timers_lock);
     g_free(timer_list);
 }
 
 static void qemu_clock_init(QEMUClockType type, QEMUTimerListNotifyCB *notify_cb)
 {
     QEMUClock *clock = qemu_clock_ptr(type);
 
     /* Assert that the clock of type TYPE has not been initialized yet. */
     assert(main_loop_tlg.tl[type] == NULL);
 
     clock->type = type;
     clock->enabled = (type == QEMU_CLOCK_VIRTUAL ? false : true);
     QLIST_INIT(&clock->timerlists);
     main_loop_tlg.tl[type] = timerlist_new(type, notify_cb, NULL);
 }
 
 bool qemu_clock_use_for_deadline(QEMUClockType type)
 {
     return !(icount_enabled() && (type == QEMU_CLOCK_VIRTUAL));
 }
 
 void qemu_clock_notify(QEMUClockType type)
 {
     QEMUTimerList *timer_list;
     QEMUClock *clock = qemu_clock_ptr(type);
     QLIST_FOREACH(timer_list, &clock->timerlists, list) {
         timerlist_notify(timer_list);
     }
 }
 
 /* Disabling the clock will wait for related timerlists to stop
  * executing qemu_run_timers.  Thus, this functions should not
  * be used from the callback of a timer that is based on @clock.
  * Doing so would cause a deadlock.
  *
  * Caller should hold BQL.
  */
 void qemu_clock_enable(QEMUClockType type, bool enabled)
 {
     QEMUClock *clock = qemu_clock_ptr(type);
     QEMUTimerList *tl;
     bool old = clock->enabled;
     clock->enabled = enabled;
     if (enabled && !old) {
         qemu_clock_notify(type);
     } else if (!enabled && old) {
         QLIST_FOREACH(tl, &clock->timerlists, list) {
             qemu_event_wait(&tl->timers_done_ev);
         }
     }
 }
 
 bool timerlist_has_timers(QEMUTimerList *timer_list)
 {
     return !!qatomic_read(&timer_list->active_timers);
 }
 
 bool qemu_clock_has_timers(QEMUClockType type)
 {
     return timerlist_has_timers(
         main_loop_tlg.tl[type]);
 }
 
 bool timerlist_expired(QEMUTimerList *timer_list)
 {
     int64_t expire_time;
 
     if (!qatomic_read(&timer_list->active_timers)) {
         return false;
     }
 
     WITH_QEMU_LOCK_GUARD(&timer_list->active_timers_lock) {
         if (!timer_list->active_timers) {
             return false;
         }
         expire_time = timer_list->active_timers->expire_time;
     }
 
     return expire_time <= qemu_clock_get_ns(timer_list->clock->type);
 }
 
 bool qemu_clock_expired(QEMUClockType type)
 {
     return timerlist_expired(
         main_loop_tlg.tl[type]);
 }
 
 /*
  * As above, but return -1 for no deadline, and do not cap to 2^32
  * as we know the result is always positive.
  */
 
 int64_t timerlist_deadline_ns(QEMUTimerList *timer_list)
 {
     int64_t delta;
     int64_t expire_time;
 
     if (!qatomic_read(&timer_list->active_timers)) {
         return -1;
     }
 
     if (!timer_list->clock->enabled) {
         return -1;
     }
 
     /* The active timers list may be modified before the caller uses our return
      * value but ->notify_cb() is called when the deadline changes.  Therefore
      * the caller should notice the change and there is no race condition.
      */
     WITH_QEMU_LOCK_GUARD(&timer_list->active_timers_lock) {
         if (!timer_list->active_timers) {
             return -1;
         }
         expire_time = timer_list->active_timers->expire_time;
     }
 
     delta = expire_time - qemu_clock_get_ns(timer_list->clock->type);
 
     if (delta <= 0) {
         return 0;
     }
 
     return delta;
 }
 
 /* Calculate the soonest deadline across all timerlists attached
  * to the clock. This is used for the icount timeout so we
  * ignore whether or not the clock should be used in deadline
  * calculations.
  */
 int64_t qemu_clock_deadline_ns_all(QEMUClockType type, int attr_mask)
 {
     int64_t deadline = -1;
     int64_t delta;
     int64_t expire_time;
     QEMUTimer *ts;
     QEMUTimerList *timer_list;
     QEMUClock *clock = qemu_clock_ptr(type);
 
     if (!clock->enabled) {
         return -1;
     }
 
     QLIST_FOREACH(timer_list, &clock->timerlists, list) {
         if (!qatomic_read(&timer_list->active_timers)) {
             continue;
         }
         qemu_mutex_lock(&timer_list->active_timers_lock);
         ts = timer_list->active_timers;
         /* Skip all external timers */
         while (ts && (ts->attributes & ~attr_mask)) {
             ts = ts->next;
         }
         if (!ts) {
             qemu_mutex_unlock(&timer_list->active_timers_lock);
             continue;
         }
         expire_time = ts->expire_time;
         qemu_mutex_unlock(&timer_list->active_timers_lock);
 
         delta = expire_time - qemu_clock_get_ns(type);
         if (delta <= 0) {
             delta = 0;
         }
         deadline = qemu_soonest_timeout(deadline, delta);
     }
     return deadline;
 }
 
 QEMUClockType timerlist_get_clock(QEMUTimerList *timer_list)
 {
     return timer_list->clock->type;
 }
 
 QEMUTimerList *qemu_clock_get_main_loop_timerlist(QEMUClockType type)
 {
     return main_loop_tlg.tl[type];
 }
 
 void timerlist_notify(QEMUTimerList *timer_list)
 {
     if (timer_list->notify_cb) {
         timer_list->notify_cb(timer_list->notify_opaque, timer_list->clock->type);
     } else {
         qemu_notify_event();
     }
 }
 
 /* Transition function to convert a nanosecond timeout to ms
  * This is used where a system does not support ppoll
  */
 int qemu_timeout_ns_to_ms(int64_t ns)
 {
     int64_t ms;
     if (ns < 0) {
         return -1;
     }
 
     if (!ns) {
         return 0;
     }
 
     /* Always round up, because it's better to wait too long than to wait too
      * little and effectively busy-wait
      */
     ms = DIV_ROUND_UP(ns, SCALE_MS);
 
     /* To avoid overflow problems, limit this to 2^31, i.e. approx 25 days */
     return MIN(ms, INT32_MAX);
 }
 
 
 /* qemu implementation of g_poll which uses a nanosecond timeout but is
  * otherwise identical to g_poll
  */
 int qemu_poll_ns(GPollFD *fds, guint nfds, int64_t timeout)
 {
 #ifdef CONFIG_PPOLL
     if (timeout < 0) {
         return ppoll((struct pollfd *)fds, nfds, NULL, NULL);
     } else {
         struct timespec ts;
         int64_t tvsec = timeout / 1000000000LL;
         /* Avoid possibly overflowing and specifying a negative number of
          * seconds, which would turn a very long timeout into a busy-wait.
          */
         if (tvsec > (int64_t)INT32_MAX) {
             tvsec = INT32_MAX;
         }
         ts.tv_sec = tvsec;
         ts.tv_nsec = timeout % 1000000000LL;
         return ppoll((struct pollfd *)fds, nfds, &ts, NULL);
     }
 #else
     return g_poll(fds, nfds, qemu_timeout_ns_to_ms(timeout));
 #endif
 }
 
 
 void timer_init_full(QEMUTimer *ts,
                      QEMUTimerListGroup *timer_list_group, QEMUClockType type,
                      int scale, int attributes,
                      QEMUTimerCB *cb, void *opaque)
 {
     if (!timer_list_group) {
         timer_list_group = &main_loop_tlg;
     }
     ts->timer_list = timer_list_group->tl[type];
     ts->cb = cb;
     ts->opaque = opaque;
     ts->scale = scale;
     ts->attributes = attributes;
     ts->expire_time = -1;
 }
 
 void timer_deinit(QEMUTimer *ts)
 {
     assert(ts->expire_time == -1);
     ts->timer_list = NULL;
 }
 
 static void timer_del_locked(QEMUTimerList *timer_list, QEMUTimer *ts)
 {
     QEMUTimer **pt, *t;
 
     ts->expire_time = -1;
     pt = &timer_list->active_timers;
     for(;;) {
         t = *pt;
         if (!t)
             break;
         if (t == ts) {
             qatomic_set(pt, t->next);
             break;
         }
         pt = &t->next;
     }
 }
 
 static bool timer_mod_ns_locked(QEMUTimerList *timer_list,
                                 QEMUTimer *ts, int64_t expire_time)
 {
     QEMUTimer **pt, *t;
 
     /* add the timer in the sorted list */
     pt = &timer_list->active_timers;
     for (;;) {
         t = *pt;
         if (!timer_expired_ns(t, expire_time)) {
             break;
         }
         pt = &t->next;
     }
     ts->expire_time = MAX(expire_time, 0);
     ts->next = *pt;
     qatomic_set(pt, ts);
 
     return pt == &timer_list->active_timers;
 }
 
 static void timerlist_rearm(QEMUTimerList *timer_list)
 {
     /* Interrupt execution to force deadline recalculation.  */
     if (icount_enabled() && timer_list->clock->type == QEMU_CLOCK_VIRTUAL) {
         icount_start_warp_timer();
     }
     timerlist_notify(timer_list);
 }
 
 /* stop a timer, but do not dealloc it */
 void timer_del(QEMUTimer *ts)
 {
     QEMUTimerList *timer_list = ts->timer_list;
 
     if (timer_list) {
         qemu_mutex_lock(&timer_list->active_timers_lock);
         timer_del_locked(timer_list, ts);
         qemu_mutex_unlock(&timer_list->active_timers_lock);
     }
 }
 
 /* modify the current timer so that it will be fired when current_time
    >= expire_time. The corresponding callback will be called. */
 void timer_mod_ns(QEMUTimer *ts, int64_t expire_time)
 {
     QEMUTimerList *timer_list = ts->timer_list;
     bool rearm;
 
     qemu_mutex_lock(&timer_list->active_timers_lock);
     timer_del_locked(timer_list, ts);
     rearm = timer_mod_ns_locked(timer_list, ts, expire_time);
     qemu_mutex_unlock(&timer_list->active_timers_lock);
 
     if (rearm) {
         timerlist_rearm(timer_list);
     }
 }
 
 /* modify the current timer so that it will be fired when current_time
    >= expire_time or the current deadline, whichever comes earlier.
    The corresponding callback will be called. */
 void timer_mod_anticipate_ns(QEMUTimer *ts, int64_t expire_time)
 {
     QEMUTimerList *timer_list = ts->timer_list;
     bool rearm;
 
     WITH_QEMU_LOCK_GUARD(&timer_list->active_timers_lock) {
         if (ts->expire_time == -1 || ts->expire_time > expire_time) {
             if (ts->expire_time != -1) {
                 timer_del_locked(timer_list, ts);
             }
             rearm = timer_mod_ns_locked(timer_list, ts, expire_time);
         } else {
             rearm = false;
         }
     }
     if (rearm) {
         timerlist_rearm(timer_list);
     }
 }
 
 void timer_mod(QEMUTimer *ts, int64_t expire_time)
 {
     timer_mod_ns(ts, expire_time * ts->scale);
 }
 
 void timer_mod_anticipate(QEMUTimer *ts, int64_t expire_time)
 {
     timer_mod_anticipate_ns(ts, expire_time * ts->scale);
 }
 
 bool timer_pending(QEMUTimer *ts)
 {
     return ts->expire_time >= 0;
 }
 
 bool timer_expired(QEMUTimer *timer_head, int64_t current_time)
 {
     return timer_expired_ns(timer_head, current_time * timer_head->scale);
 }
 
 bool timerlist_run_timers(QEMUTimerList *timer_list)
 {
     QEMUTimer *ts;
     int64_t current_time;
     bool progress = false;
     QEMUTimerCB *cb;
     void *opaque;
 
     if (!qatomic_read(&timer_list->active_timers)) {
         return false;
     }
 
     qemu_event_reset(&timer_list->timers_done_ev);
     if (!timer_list->clock->enabled) {
         goto out;
     }
 
     switch (timer_list->clock->type) {
     case QEMU_CLOCK_REALTIME:
         break;
     default:
     case QEMU_CLOCK_VIRTUAL:
         break;
     case QEMU_CLOCK_HOST:
         if (!replay_checkpoint(CHECKPOINT_CLOCK_HOST)) {
             goto out;
         }
         break;
     case QEMU_CLOCK_VIRTUAL_RT:
         if (!replay_checkpoint(CHECKPOINT_CLOCK_VIRTUAL_RT)) {
             goto out;
         }
         break;
     }
 
     /*
      * Extract expired timers from active timers list and process them.
      *
      * In rr mode we need "filtered" checkpointing for virtual clock.  The
      * checkpoint must be recorded/replayed before processing any non-EXTERNAL timer,
      * and that must only be done once since the clock value stays the same. Because
      * non-EXTERNAL timers may appear in the timers list while it being processed,
      * the checkpoint can be issued at a time until no timers are left and we are
      * done".
      */
     current_time = qemu_clock_get_ns(timer_list->clock->type);
     qemu_mutex_lock(&timer_list->active_timers_lock);
     while ((ts = timer_list->active_timers)) {
         if (!timer_expired_ns(ts, current_time)) {
             /* No expired timers left.  The checkpoint can be skipped
              * if no timers fired or they were all external.
              */
             break;
         }
         /* Checkpoint for virtual clock is redundant in cases where
          * it's being triggered with only non-EXTERNAL timers, because
          * these timers don't change guest state directly.
          */
         if (replay_mode != REPLAY_MODE_NONE
             && timer_list->clock->type == QEMU_CLOCK_VIRTUAL
             && !(ts->attributes & QEMU_TIMER_ATTR_EXTERNAL)
             && !replay_checkpoint(CHECKPOINT_CLOCK_VIRTUAL)) {
             qemu_mutex_unlock(&timer_list->active_timers_lock);
             goto out;
         }
 
         /* remove timer from the list before calling the callback */
         timer_list->active_timers = ts->next;
         ts->next = NULL;
         ts->expire_time = -1;
         cb = ts->cb;
         opaque = ts->opaque;
 
         /* run the callback (the timer list can be modified) */
         qemu_mutex_unlock(&timer_list->active_timers_lock);
         cb(opaque);
         qemu_mutex_lock(&timer_list->active_timers_lock);
 
         progress = true;
     }
     qemu_mutex_unlock(&timer_list->active_timers_lock);
 
 out:
     qemu_event_set(&timer_list->timers_done_ev);
     return progress;
 }
 
 bool qemu_clock_run_timers(QEMUClockType type)
 {
     return timerlist_run_timers(main_loop_tlg.tl[type]);
 }
 
 void timerlistgroup_init(QEMUTimerListGroup *tlg,
                          QEMUTimerListNotifyCB *cb, void *opaque)
 {
     QEMUClockType type;
     for (type = 0; type < QEMU_CLOCK_MAX; type++) {
         tlg->tl[type] = timerlist_new(type, cb, opaque);
     }
 }
 
 void timerlistgroup_deinit(QEMUTimerListGroup *tlg)
 {
     QEMUClockType type;
     for (type = 0; type < QEMU_CLOCK_MAX; type++) {
         timerlist_free(tlg->tl[type]);
     }
 }
 
 bool timerlistgroup_run_timers(QEMUTimerListGroup *tlg)
 {
     QEMUClockType type;
     bool progress = false;
     for (type = 0; type < QEMU_CLOCK_MAX; type++) {
         progress |= timerlist_run_timers(tlg->tl[type]);
     }
     return progress;
 }
 
 int64_t timerlistgroup_deadline_ns(QEMUTimerListGroup *tlg)
 {
     int64_t deadline = -1;
     QEMUClockType type;
     for (type = 0; type < QEMU_CLOCK_MAX; type++) {
         if (qemu_clock_use_for_deadline(type)) {
             deadline = qemu_soonest_timeout(deadline,
                                             timerlist_deadline_ns(tlg->tl[type]));
         }
     }
     return deadline;
 }
 
 int64_t qemu_clock_get_ns(QEMUClockType type)
 {
     switch (type) {
     case QEMU_CLOCK_REALTIME:
         return get_clock();
     default:
     case QEMU_CLOCK_VIRTUAL:
         return cpus_get_virtual_clock();
     case QEMU_CLOCK_HOST:
         return REPLAY_CLOCK(REPLAY_CLOCK_HOST, get_clock_realtime());
     case QEMU_CLOCK_VIRTUAL_RT:
         return REPLAY_CLOCK(REPLAY_CLOCK_VIRTUAL_RT, cpu_get_clock());
     }
 }
 
 void init_clocks(QEMUTimerListNotifyCB *notify_cb)
 {
     QEMUClockType type;
     for (type = 0; type < QEMU_CLOCK_MAX; type++) {
         qemu_clock_init(type, notify_cb);
     }
 
 #ifdef CONFIG_PRCTL_PR_SET_TIMERSLACK
     prctl(PR_SET_TIMERSLACK, 1, 0, 0, 0);
 #endif
 }
 
 uint64_t timer_expire_time_ns(QEMUTimer *ts)
 {
     return timer_pending(ts) ? ts->expire_time : -1;
 }
 
 bool qemu_clock_run_all_timers(void)
 {
     bool progress = false;
     QEMUClockType type;
 
     for (type = 0; type < QEMU_CLOCK_MAX; type++) {
         if (qemu_clock_use_for_deadline(type)) {
             progress |= qemu_clock_run_timers(type);
         }
     }
 
     return progress;
 }