timer: Remove reset notifiers

[thirdparty/qemu.git] / util / qemu-timer.c

diff --git a/util/qemu-timer.c b/util/qemu-timer.c
index 86bfe84037ac400f0ea17a839c7d6bfd18090d3f..1ac831434dec6ce736cb8116608b386148d70896 100644 (file)
--- a/util/qemu-timer.c
+++ b/util/qemu-timer.c
@@ -26,7 +26,6 @@
 #include "qemu/main-loop.h"
 #include "qemu/timer.h"
 #include "sysemu/replay.h"
-#include "sysemu/sysemu.h"
 #include "sysemu/cpus.h"
 
 #ifdef CONFIG_POSIX
@@ -48,7 +47,6 @@ typedef struct QEMUClock {
     /* We rely on BQL to protect the timerlists */
     QLIST_HEAD(, QEMUTimerList) timerlists;
 
-    NotifierList reset_notifiers;
     int64_t last;
 
     QEMUClockType type;
@@ -133,7 +131,6 @@ static void qemu_clock_init(QEMUClockType type, QEMUTimerListNotifyCB *notify_cb
     clock->enabled = (type == QEMU_CLOCK_VIRTUAL ? false : true);
     clock->last = INT64_MIN;
     QLIST_INIT(&clock->timerlists);
-    notifier_list_init(&clock->reset_notifiers);
     main_loop_tlg.tl[type] = timerlist_new(type, notify_cb, NULL);
 }
 
@@ -339,14 +336,19 @@ int qemu_poll_ns(GPollFD *fds, guint nfds, int64_t timeout)
 }
 
 
-void timer_init_tl(QEMUTimer *ts,
-                   QEMUTimerList *timer_list, int scale,
-                   QEMUTimerCB *cb, void *opaque)
+void timer_init_full(QEMUTimer *ts,
+                     QEMUTimerListGroup *timer_list_group, QEMUClockType type,
+                     int scale, int attributes,
+                     QEMUTimerCB *cb, void *opaque)
 {
-    ts->timer_list = timer_list;
+    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;
 }
 
@@ -484,6 +486,7 @@ bool timerlist_run_timers(QEMUTimerList *timer_list)
     bool progress = false;
     QEMUTimerCB *cb;
     void *opaque;
+    bool need_replay_checkpoint = false;
 
     if (!atomic_read(&timer_list->active_timers)) {
         return false;
@@ -499,8 +502,15 @@ bool timerlist_run_timers(QEMUTimerList *timer_list)
         break;
     default:
     case QEMU_CLOCK_VIRTUAL:
-        if (!replay_checkpoint(CHECKPOINT_CLOCK_VIRTUAL)) {
-            goto out;
+        if (replay_mode != REPLAY_MODE_NONE) {
+            /* 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.
+             * Since it has conditional dependence on specific timers, it is
+             * subject to race conditions and requires special handling.
+             * See below.
+             */
+            need_replay_checkpoint = true;
         }
         break;
     case QEMU_CLOCK_HOST:
@@ -515,14 +525,39 @@ bool timerlist_run_timers(QEMUTimerList *timer_list)
         break;
     }
 
+    /*
+     * Extract expired timers from active timers list and 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);
-    for(;;) {
-        qemu_mutex_lock(&timer_list->active_timers_lock);
-        ts = timer_list->active_timers;
+    qemu_mutex_lock(&timer_list->active_timers_lock);
+    while ((ts = timer_list->active_timers)) {
         if (!timer_expired_ns(ts, current_time)) {
-            qemu_mutex_unlock(&timer_list->active_timers_lock);
+            /* No expired timers left.  The checkpoint can be skipped
+             * if no timers fired or they were all external.
+             */
             break;
         }
+        if (need_replay_checkpoint
+                && !(ts->attributes & QEMU_TIMER_ATTR_EXTERNAL)) {
+            /* once we got here, checkpoint clock only once */
+            need_replay_checkpoint = false;
+            qemu_mutex_unlock(&timer_list->active_timers_lock);
+            if (!replay_checkpoint(CHECKPOINT_CLOCK_VIRTUAL)) {
+                goto out;
+            }
+            qemu_mutex_lock(&timer_list->active_timers_lock);
+            /* The lock was released; start over again in case the list was
+             * modified.
+             */
+            continue;
+        }
 
         /* remove timer from the list before calling the callback */
         timer_list->active_timers = ts->next;
@@ -530,12 +565,15 @@ bool timerlist_run_timers(QEMUTimerList *timer_list)
         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) */
+        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);
@@ -589,7 +627,7 @@ int64_t timerlistgroup_deadline_ns(QEMUTimerListGroup *tlg)
 
 int64_t qemu_clock_get_ns(QEMUClockType type)
 {
-    int64_t now, last;
+    int64_t now;
     QEMUClock *clock = qemu_clock_ptr(type);
 
     switch (type) {
@@ -604,11 +642,7 @@ int64_t qemu_clock_get_ns(QEMUClockType type)
         }
     case QEMU_CLOCK_HOST:
         now = REPLAY_CLOCK(REPLAY_CLOCK_HOST, get_clock_realtime());
-        last = clock->last;
         clock->last = now;
-        if (now < last || now > (last + get_max_clock_jump())) {
-            notifier_list_notify(&clock->reset_notifiers, &now);
-        }
         return now;
     case QEMU_CLOCK_VIRTUAL_RT:
         return REPLAY_CLOCK(REPLAY_CLOCK_VIRTUAL_RT, cpu_get_clock());
@@ -627,19 +661,6 @@ void qemu_clock_set_last(QEMUClockType type, uint64_t last)
     clock->last = last;
 }
 
-void qemu_clock_register_reset_notifier(QEMUClockType type,
-                                        Notifier *notifier)
-{
-    QEMUClock *clock = qemu_clock_ptr(type);
-    notifier_list_add(&clock->reset_notifiers, notifier);
-}
-
-void qemu_clock_unregister_reset_notifier(QEMUClockType type,
-                                          Notifier *notifier)
-{
-    notifier_remove(notifier);
-}
-
 void init_clocks(QEMUTimerListNotifyCB *notify_cb)
 {
     QEMUClockType type;