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authorPaolo Bonzini <pbonzini@redhat.com>2013-09-12 11:02:20 +0200
committerStefan Hajnoczi <stefanha@redhat.com>2013-09-18 15:48:33 +0200
commit3db1ee7c2af2fbbfe259712e3ce74158bc667ad3 (patch)
treee251ed3d3324e051c0ff37aa929f3b33dd5f9e3a
parent978f2205c791de0e02c8802a645bea657408abfd (diff)
qemu-timer: do not take the lock in timer_pending
We can deduce the result from expire_time, by making it always -1 if the timer is not in the active_timers list. We need to check against negative times passed to timer_mod_ns; clamping them to zero is not a problem because the only clock that has a zero value at VM startup is QEMU_CLOCK_VIRTUAL, and it is monotonic so it cannot be non-zero. QEMU_CLOCK_HOST, instead, is not monotonic but it cannot go to negative values unless the host time is seriously screwed up and points to the 1960s. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
-rw-r--r--qemu-timer.c19
1 files changed, 5 insertions, 14 deletions
diff --git a/qemu-timer.c b/qemu-timer.c
index e5047479f2..6b62e88669 100644
--- a/qemu-timer.c
+++ b/qemu-timer.c
@@ -312,6 +312,7 @@ void timer_init(QEMUTimer *ts,
ts->cb = cb;
ts->opaque = opaque;
ts->scale = scale;
+ ts->expire_time = -1;
}
void timer_free(QEMUTimer *ts)
@@ -323,6 +324,7 @@ 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;
@@ -365,7 +367,7 @@ void timer_mod_ns(QEMUTimer *ts, int64_t expire_time)
}
pt = &t->next;
}
- ts->expire_time = expire_time;
+ ts->expire_time = MAX(expire_time, 0);
ts->next = *pt;
*pt = ts;
qemu_mutex_unlock(&timer_list->active_timers_lock);
@@ -385,19 +387,7 @@ void timer_mod(QEMUTimer *ts, int64_t expire_time)
bool timer_pending(QEMUTimer *ts)
{
- QEMUTimerList *timer_list = ts->timer_list;
- QEMUTimer *t;
- bool found = false;
-
- qemu_mutex_lock(&timer_list->active_timers_lock);
- for (t = timer_list->active_timers; t != NULL; t = t->next) {
- if (t == ts) {
- found = true;
- break;
- }
- }
- qemu_mutex_unlock(&timer_list->active_timers_lock);
- return found;
+ return ts->expire_time >= 0;
}
bool timer_expired(QEMUTimer *timer_head, int64_t current_time)
@@ -429,6 +419,7 @@ bool timerlist_run_timers(QEMUTimerList *timer_list)
/* 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);