/* timers */
typedef struct QEMUClock {
+ /* We rely on BQL to protect the timerlists */
QLIST_HEAD(, QEMUTimerList) timerlists;
NotifierList reset_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;
};
/**
QEMUClock *clock = qemu_clock_ptr(type);
timer_list = g_malloc0(sizeof(QEMUTimerList));
+ qemu_event_init(&timer_list->timers_done_ev, false);
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;
}
if (timer_list->clock) {
QLIST_REMOVE(timer_list, list);
}
+ qemu_mutex_destroy(&timer_list->active_timers_lock);
g_free(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_expired(QEMUTimerList *timer_list)
{
- return (timer_list->active_timers &&
- timer_list->active_timers->expire_time <
- qemu_clock_get_ns(timer_list->clock->type));
+ int64_t expire_time;
+
+ qemu_mutex_lock(&timer_list->active_timers_lock);
+ if (!timer_list->active_timers) {
+ qemu_mutex_unlock(&timer_list->active_timers_lock);
+ return false;
+ }
+ expire_time = timer_list->active_timers->expire_time;
+ qemu_mutex_unlock(&timer_list->active_timers_lock);
+
+ return expire_time < qemu_clock_get_ns(timer_list->clock->type);
}
bool qemu_clock_expired(QEMUClockType type)
int64_t timerlist_deadline_ns(QEMUTimerList *timer_list)
{
int64_t delta;
+ int64_t expire_time;
- if (!timer_list->clock->enabled || !timer_list->active_timers) {
+ if (!timer_list->clock->enabled) {
return -1;
}
- delta = timer_list->active_timers->expire_time -
- qemu_clock_get_ns(timer_list->clock->type);
+ /* 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.
+ */
+ qemu_mutex_lock(&timer_list->active_timers_lock);
+ if (!timer_list->active_timers) {
+ qemu_mutex_unlock(&timer_list->active_timers_lock);
+ return -1;
+ }
+ expire_time = timer_list->active_timers->expire_time;
+ qemu_mutex_unlock(&timer_list->active_timers_lock);
+
+ delta = expire_time - qemu_clock_get_ns(timer_list->clock->type);
if (delta <= 0) {
return 0;
ts->cb = cb;
ts->opaque = opaque;
ts->scale = scale;
+ ts->expire_time = -1;
}
void timer_free(QEMUTimer *ts)
g_free(ts);
}
-/* stop a timer, but do not dealloc it */
-void timer_del(QEMUTimer *ts)
+static void timer_del_locked(QEMUTimerList *timer_list, QEMUTimer *ts)
{
QEMUTimer **pt, *t;
- /* NOTE: this code must be signal safe because
- timer_expired() can be called from a signal. */
- pt = &ts->timer_list->active_timers;
+ ts->expire_time = -1;
+ pt = &timer_list->active_timers;
for(;;) {
t = *pt;
if (!t)
}
}
-/* 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)
+static bool timer_mod_ns_locked(QEMUTimerList *timer_list,
+ QEMUTimer *ts, int64_t expire_time)
{
QEMUTimer **pt, *t;
- timer_del(ts);
-
/* add the timer in the sorted list */
- /* NOTE: this code must be signal safe because
- timer_expired() can be called from a signal. */
- pt = &ts->timer_list->active_timers;
- for(;;) {
+ pt = &timer_list->active_timers;
+ for (;;) {
t = *pt;
if (!timer_expired_ns(t, expire_time)) {
break;
}
pt = &t->next;
}
- ts->expire_time = expire_time;
+ ts->expire_time = MAX(expire_time, 0);
ts->next = *pt;
*pt = ts;
- /* Rearm if necessary */
- if (pt == &ts->timer_list->active_timers) {
- /* Interrupt execution to force deadline recalculation. */
- qemu_clock_warp(ts->timer_list->clock->type);
- timerlist_notify(ts->timer_list);
+ return pt == &timer_list->active_timers;
+}
+
+static void timerlist_rearm(QEMUTimerList *timer_list)
+{
+ /* Interrupt execution to force deadline recalculation. */
+ qemu_clock_warp(timer_list->clock->type);
+ timerlist_notify(timer_list);
+}
+
+/* stop a timer, but do not dealloc it */
+void timer_del(QEMUTimer *ts)
+{
+ QEMUTimerList *timer_list = ts->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;
+
+ qemu_mutex_lock(&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;
+ }
+ qemu_mutex_unlock(&timer_list->active_timers_lock);
+
+ if (rearm) {
+ timerlist_rearm(timer_list);
}
}
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)
{
- QEMUTimer *t;
- for (t = ts->timer_list->active_timers; t != NULL; t = t->next) {
- if (t == ts) {
- return true;
- }
- }
- return false;
+ return ts->expire_time >= 0;
}
bool timer_expired(QEMUTimer *timer_head, int64_t current_time)
QEMUTimer *ts;
int64_t current_time;
bool progress = false;
-
+ QEMUTimerCB *cb;
+ void *opaque;
+
+ qemu_event_reset(&timer_list->timers_done_ev);
if (!timer_list->clock->enabled) {
- return progress;
+ goto out;
}
current_time = qemu_clock_get_ns(timer_list->clock->type);
for(;;) {
+ qemu_mutex_lock(&timer_list->active_timers_lock);
ts = timer_list->active_timers;
if (!timer_expired_ns(ts, current_time)) {
+ qemu_mutex_unlock(&timer_list->active_timers_lock);
break;
}
+
/* 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;
+ qemu_mutex_unlock(&timer_list->active_timers_lock);
/* run the callback (the timer list can be modified) */
- ts->cb(ts->opaque);
+ cb(opaque);
progress = true;
}
+
+out:
+ qemu_event_set(&timer_list->timers_done_ev);
return progress;
}
projects / qemu.git / blobdiff