From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:57721) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VF1Ns-0003uP-24 for qemu-devel@nongnu.org; Thu, 29 Aug 2013 08:31:40 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1VF1Nj-0002Fq-MP for qemu-devel@nongnu.org; Thu, 29 Aug 2013 08:31:32 -0400 Received: from mail-ee0-x235.google.com ([2a00:1450:4013:c00::235]:42131) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VF1Nj-0002F0-7x for qemu-devel@nongnu.org; Thu, 29 Aug 2013 08:31:23 -0400 Received: by mail-ee0-f53.google.com with SMTP id b15so203599eek.26 for ; Thu, 29 Aug 2013 05:31:22 -0700 (PDT) Sender: Paolo Bonzini From: Paolo Bonzini Date: Thu, 29 Aug 2013 14:31:01 +0200 Message-Id: <1377779462-24383-4-git-send-email-pbonzini@redhat.com> In-Reply-To: <1377779462-24383-1-git-send-email-pbonzini@redhat.com> References: <1377779462-24383-1-git-send-email-pbonzini@redhat.com> Subject: [Qemu-devel] [RFC PATCH 3/3] qemu-timer: do not take the lock in timer_pending List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: qemulist@gmail.com, stefanha@redhat.com 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 --- qemu-timer.c | 19 +++++-------------- 1 file changed, 5 insertions(+), 14 deletions(-) diff --git a/qemu-timer.c b/qemu-timer.c index aa22801..807319a 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) @@ -324,6 +325,7 @@ 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; @@ -366,7 +368,7 @@ 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); @@ -386,19 +388,7 @@ 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) @@ -430,6 +420,7 @@ 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