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-rw-r--r--kernel/timer.c110
1 files changed, 73 insertions, 37 deletions
diff --git a/kernel/timer.c b/kernel/timer.c
index 13dd64fe143d..9b77fc9a9ac8 100644
--- a/kernel/timer.c
+++ b/kernel/timer.c
@@ -589,11 +589,14 @@ static struct tvec_base *lock_timer_base(struct timer_list *timer,
589 } 589 }
590} 590}
591 591
592int __mod_timer(struct timer_list *timer, unsigned long expires) 592static inline int
593__mod_timer(struct timer_list *timer, unsigned long expires, bool pending_only)
593{ 594{
594 struct tvec_base *base, *new_base; 595 struct tvec_base *base, *new_base;
595 unsigned long flags; 596 unsigned long flags;
596 int ret = 0; 597 int ret;
598
599 ret = 0;
597 600
598 timer_stats_timer_set_start_info(timer); 601 timer_stats_timer_set_start_info(timer);
599 BUG_ON(!timer->function); 602 BUG_ON(!timer->function);
@@ -603,6 +606,9 @@ int __mod_timer(struct timer_list *timer, unsigned long expires)
603 if (timer_pending(timer)) { 606 if (timer_pending(timer)) {
604 detach_timer(timer, 0); 607 detach_timer(timer, 0);
605 ret = 1; 608 ret = 1;
609 } else {
610 if (pending_only)
611 goto out_unlock;
606 } 612 }
607 613
608 debug_timer_activate(timer); 614 debug_timer_activate(timer);
@@ -629,42 +635,28 @@ int __mod_timer(struct timer_list *timer, unsigned long expires)
629 635
630 timer->expires = expires; 636 timer->expires = expires;
631 internal_add_timer(base, timer); 637 internal_add_timer(base, timer);
638
639out_unlock:
632 spin_unlock_irqrestore(&base->lock, flags); 640 spin_unlock_irqrestore(&base->lock, flags);
633 641
634 return ret; 642 return ret;
635} 643}
636 644
637EXPORT_SYMBOL(__mod_timer);
638
639/** 645/**
640 * add_timer_on - start a timer on a particular CPU 646 * mod_timer_pending - modify a pending timer's timeout
641 * @timer: the timer to be added 647 * @timer: the pending timer to be modified
642 * @cpu: the CPU to start it on 648 * @expires: new timeout in jiffies
643 * 649 *
644 * This is not very scalable on SMP. Double adds are not possible. 650 * mod_timer_pending() is the same for pending timers as mod_timer(),
651 * but will not re-activate and modify already deleted timers.
652 *
653 * It is useful for unserialized use of timers.
645 */ 654 */
646void add_timer_on(struct timer_list *timer, int cpu) 655int mod_timer_pending(struct timer_list *timer, unsigned long expires)
647{ 656{
648 struct tvec_base *base = per_cpu(tvec_bases, cpu); 657 return __mod_timer(timer, expires, true);
649 unsigned long flags;
650
651 timer_stats_timer_set_start_info(timer);
652 BUG_ON(timer_pending(timer) || !timer->function);
653 spin_lock_irqsave(&base->lock, flags);
654 timer_set_base(timer, base);
655 debug_timer_activate(timer);
656 internal_add_timer(base, timer);
657 /*
658 * Check whether the other CPU is idle and needs to be
659 * triggered to reevaluate the timer wheel when nohz is
660 * active. We are protected against the other CPU fiddling
661 * with the timer by holding the timer base lock. This also
662 * makes sure that a CPU on the way to idle can not evaluate
663 * the timer wheel.
664 */
665 wake_up_idle_cpu(cpu);
666 spin_unlock_irqrestore(&base->lock, flags);
667} 658}
659EXPORT_SYMBOL(mod_timer_pending);
668 660
669/** 661/**
670 * mod_timer - modify a timer's timeout 662 * mod_timer - modify a timer's timeout
@@ -688,9 +680,6 @@ void add_timer_on(struct timer_list *timer, int cpu)
688 */ 680 */
689int mod_timer(struct timer_list *timer, unsigned long expires) 681int mod_timer(struct timer_list *timer, unsigned long expires)
690{ 682{
691 BUG_ON(!timer->function);
692
693 timer_stats_timer_set_start_info(timer);
694 /* 683 /*
695 * This is a common optimization triggered by the 684 * This is a common optimization triggered by the
696 * networking code - if the timer is re-modified 685 * networking code - if the timer is re-modified
@@ -699,12 +688,62 @@ int mod_timer(struct timer_list *timer, unsigned long expires)
699 if (timer->expires == expires && timer_pending(timer)) 688 if (timer->expires == expires && timer_pending(timer))
700 return 1; 689 return 1;
701 690
702 return __mod_timer(timer, expires); 691 return __mod_timer(timer, expires, false);
703} 692}
704
705EXPORT_SYMBOL(mod_timer); 693EXPORT_SYMBOL(mod_timer);
706 694
707/** 695/**
696 * add_timer - start a timer
697 * @timer: the timer to be added
698 *
699 * The kernel will do a ->function(->data) callback from the
700 * timer interrupt at the ->expires point in the future. The
701 * current time is 'jiffies'.
702 *
703 * The timer's ->expires, ->function (and if the handler uses it, ->data)
704 * fields must be set prior calling this function.
705 *
706 * Timers with an ->expires field in the past will be executed in the next
707 * timer tick.
708 */
709void add_timer(struct timer_list *timer)
710{
711 BUG_ON(timer_pending(timer));
712 mod_timer(timer, timer->expires);
713}
714EXPORT_SYMBOL(add_timer);
715
716/**
717 * add_timer_on - start a timer on a particular CPU
718 * @timer: the timer to be added
719 * @cpu: the CPU to start it on
720 *
721 * This is not very scalable on SMP. Double adds are not possible.
722 */
723void add_timer_on(struct timer_list *timer, int cpu)
724{
725 struct tvec_base *base = per_cpu(tvec_bases, cpu);
726 unsigned long flags;
727
728 timer_stats_timer_set_start_info(timer);
729 BUG_ON(timer_pending(timer) || !timer->function);
730 spin_lock_irqsave(&base->lock, flags);
731 timer_set_base(timer, base);
732 debug_timer_activate(timer);
733 internal_add_timer(base, timer);
734 /*
735 * Check whether the other CPU is idle and needs to be
736 * triggered to reevaluate the timer wheel when nohz is
737 * active. We are protected against the other CPU fiddling
738 * with the timer by holding the timer base lock. This also
739 * makes sure that a CPU on the way to idle can not evaluate
740 * the timer wheel.
741 */
742 wake_up_idle_cpu(cpu);
743 spin_unlock_irqrestore(&base->lock, flags);
744}
745
746/**
708 * del_timer - deactive a timer. 747 * del_timer - deactive a timer.
709 * @timer: the timer to be deactivated 748 * @timer: the timer to be deactivated
710 * 749 *
@@ -733,7 +772,6 @@ int del_timer(struct timer_list *timer)
733 772
734 return ret; 773 return ret;
735} 774}
736
737EXPORT_SYMBOL(del_timer); 775EXPORT_SYMBOL(del_timer);
738 776
739#ifdef CONFIG_SMP 777#ifdef CONFIG_SMP
@@ -767,7 +805,6 @@ out:
767 805
768 return ret; 806 return ret;
769} 807}
770
771EXPORT_SYMBOL(try_to_del_timer_sync); 808EXPORT_SYMBOL(try_to_del_timer_sync);
772 809
773/** 810/**
@@ -796,7 +833,6 @@ int del_timer_sync(struct timer_list *timer)
796 cpu_relax(); 833 cpu_relax();
797 } 834 }
798} 835}
799
800EXPORT_SYMBOL(del_timer_sync); 836EXPORT_SYMBOL(del_timer_sync);
801#endif 837#endif
802 838
@@ -1268,7 +1304,7 @@ signed long __sched schedule_timeout(signed long timeout)
1268 expire = timeout + jiffies; 1304 expire = timeout + jiffies;
1269 1305
1270 setup_timer_on_stack(&timer, process_timeout, (unsigned long)current); 1306 setup_timer_on_stack(&timer, process_timeout, (unsigned long)current);
1271 __mod_timer(&timer, expire); 1307 __mod_timer(&timer, expire, false);
1272 schedule(); 1308 schedule();
1273 del_singleshot_timer_sync(&timer); 1309 del_singleshot_timer_sync(&timer);
1274 1310