1 files changed, 80 insertions, 17 deletions

diff --git a/qemu-timer.c b/qemu-timer.c
index 6b62e88669..e15ce477cc 100644
--- a/qemu-timer.c
+++ b/qemu-timer.c
@@ -45,6 +45,7 @@
 /* timers */
 
 typedef struct QEMUClock {
+    /* We rely on BQL to protect the timerlists */
     QLIST_HEAD(, QEMUTimerList) timerlists;
 
     NotifierList reset_notifiers;
@@ -71,6 +72,9 @@ struct QEMUTimerList {
     QLIST_ENTRY(QEMUTimerList) list;
     QEMUTimerListNotifyCB *notify_cb;
     void *notify_opaque;
+
+    /* lightweight method to mark the end of timerlist's running */
+    QemuEvent timers_done_ev;
 };
 
 /**
@@ -99,6 +103,7 @@ QEMUTimerList *timerlist_new(QEMUClockType type,
     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;
@@ -143,13 +148,25 @@ void qemu_clock_notify(QEMUClockType type)
     }
 }
 
+/* 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);
+        }
     }
 }
 
@@ -338,6 +355,34 @@ static void timer_del_locked(QEMUTimerList *timer_list, QEMUTimer *ts)
     }
 }
 
+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;
+    *pt = ts;
+
+    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)
 {
@@ -353,30 +398,39 @@ void timer_del(QEMUTimer *ts)
 void timer_mod_ns(QEMUTimer *ts, int64_t expire_time)
 {
     QEMUTimerList *timer_list = ts->timer_list;
-    QEMUTimer **pt, *t;
+    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);
 
-    /* add the timer in the sorted list */
-    pt = &timer_list->active_timers;
-    for(;;) {
-        t = *pt;
-        if (!timer_expired_ns(t, expire_time)) {
-            break;
+    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);
         }
-        pt = &t->next;
+        rearm = timer_mod_ns_locked(timer_list, ts, expire_time);
+    } else {
+        rearm = false;
     }
-    ts->expire_time = MAX(expire_time, 0);
-    ts->next = *pt;
-    *pt = ts;
     qemu_mutex_unlock(&timer_list->active_timers_lock);
 
-    /* Rearm if necessary  */
-    if (pt == &timer_list->active_timers) {
-        /* Interrupt execution to force deadline recalculation.  */
-        qemu_clock_warp(timer_list->clock->type);
-        timerlist_notify(timer_list);
+    if (rearm) {
+        timerlist_rearm(timer_list);
     }
 }
 
@@ -385,6 +439,11 @@ 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;
@@ -403,8 +462,9 @@ bool timerlist_run_timers(QEMUTimerList *timer_list)
     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);
@@ -428,6 +488,9 @@ bool timerlist_run_timers(QEMUTimerList *timer_list)
         cb(opaque);
         progress = true;
     }
+
+out:
+    qemu_event_set(&timer_list->timers_done_ev);
     return progress;
 }