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[Qemu-devel] [PULL 05/11] qemu-timer: do not take the lock in timer_pend
From: |
Stefan Hajnoczi |
Subject: |
[Qemu-devel] [PULL 05/11] qemu-timer: do not take the lock in timer_pending |
Date: |
Fri, 20 Sep 2013 19:42:05 +0200 |
From: Paolo Bonzini <address@hidden>
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 <address@hidden>
Signed-off-by: Stefan Hajnoczi <address@hidden>
---
qemu-timer.c | 19 +++++--------------
1 file changed, 5 insertions(+), 14 deletions(-)
diff --git a/qemu-timer.c b/qemu-timer.c
index e504747..6b62e88 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);
--
1.8.3.1
- [Qemu-devel] [PULL 00/11] Block patches, Stefan Hajnoczi, 2013/09/20
- [Qemu-devel] [PULL 01/11] libcacard: link against qemu-error.o for error_report(), Stefan Hajnoczi, 2013/09/20
- [Qemu-devel] [PULL 02/11] osdep: warn if open(O_DIRECT) on fails with EINVAL, Stefan Hajnoczi, 2013/09/20
- [Qemu-devel] [PULL 03/11] qemu-timer: drop outdated signal safety comments, Stefan Hajnoczi, 2013/09/20
- [Qemu-devel] [PULL 04/11] qemu-timer: make qemu_timer_mod_ns() and qemu_timer_del() thread-safe, Stefan Hajnoczi, 2013/09/20
- [Qemu-devel] [PULL 05/11] qemu-timer: do not take the lock in timer_pending,
Stefan Hajnoczi <=
- [Qemu-devel] [PULL 06/11] coroutine: add qemu_coroutine_yield benchmark, Stefan Hajnoczi, 2013/09/20
- [Qemu-devel] [PULL 07/11] coroutine: fix /perf/nesting coroutine benchmark, Stefan Hajnoczi, 2013/09/20
- [Qemu-devel] [PULL 08/11] qcow2: Correct snapshots size for overlap check, Stefan Hajnoczi, 2013/09/20
- [Qemu-devel] [PULL 09/11] block: don't lose data from last incomplete sector, Stefan Hajnoczi, 2013/09/20
- [Qemu-devel] [PULL 10/11] blockdev: do not default cache.no-flush to true, Stefan Hajnoczi, 2013/09/20
- [Qemu-devel] [PULL 11/11] virtio-blk: do not relay a previous driver's WCE configuration to the current, Stefan Hajnoczi, 2013/09/20