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Commit 5b2d3e6d authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge branch 'timers-fixes-for-linus' of... 

Merge branch 'timers-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

* 'timers-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  hrtimer: prevent negative expiry value after clock_was_set()
  hrtimers: allow the hot-unplugging of all cpus
  hrtimers: increase clock min delta threshold while interrupt hanging
parents f6490438 b0a9b511

include/linux/clockchips.h

+1 −0
Original line number Diff line number Diff line
@@ -36,6 +36,7 @@ enum clock_event_nofitiers { 
	CLOCK_EVT_NOTIFY_BROADCAST_EXIT,

	CLOCK_EVT_NOTIFY_SUSPEND,

	CLOCK_EVT_NOTIFY_RESUME,

	CLOCK_EVT_NOTIFY_CPU_DYING,

	CLOCK_EVT_NOTIFY_CPU_DEAD,

};

kernel/hrtimer.c

+40 −1
Original line number Diff line number Diff line
@@ -501,6 +501,13 @@ static void hrtimer_force_reprogram(struct hrtimer_cpu_base *cpu_base) 
			continue;

		timer = rb_entry(base->first, struct hrtimer, node);

		expires = ktime_sub(hrtimer_get_expires(timer), base->offset);

		/*

		 * clock_was_set() has changed base->offset so the

		 * result might be negative. Fix it up to prevent a

		 * false positive in clockevents_program_event()

		 */

		if (expires.tv64 < 0)

			expires.tv64 = 0;

		if (expires.tv64 < cpu_base->expires_next.tv64)

			cpu_base->expires_next = expires;

	}
@@ -1158,6 +1165,29 @@ static void __run_hrtimer(struct hrtimer *timer) 


#ifdef CONFIG_HIGH_RES_TIMERS



static int force_clock_reprogram;



/*

 * After 5 iteration's attempts, we consider that hrtimer_interrupt()

 * is hanging, which could happen with something that slows the interrupt

 * such as the tracing. Then we force the clock reprogramming for each future

 * hrtimer interrupts to avoid infinite loops and use the min_delta_ns

 * threshold that we will overwrite.

 * The next tick event will be scheduled to 3 times we currently spend on

 * hrtimer_interrupt(). This gives a good compromise, the cpus will spend

 * 1/4 of their time to process the hrtimer interrupts. This is enough to

 * let it running without serious starvation.

 */



static inline void

hrtimer_interrupt_hanging(struct clock_event_device *dev,

			ktime_t try_time)

{

	force_clock_reprogram = 1;

	dev->min_delta_ns = (unsigned long)try_time.tv64 * 3;

	printk(KERN_WARNING "hrtimer: interrupt too slow, "

		"forcing clock min delta to %lu ns\n", dev->min_delta_ns);

}

/*

 * High resolution timer interrupt

 * Called with interrupts disabled
@@ -1167,6 +1197,7 @@ void hrtimer_interrupt(struct clock_event_device *dev) 
	struct hrtimer_cpu_base *cpu_base = &__get_cpu_var(hrtimer_bases);

	struct hrtimer_clock_base *base;

	ktime_t expires_next, now;

	int nr_retries = 0;

	int i;



	BUG_ON(!cpu_base->hres_active);
@@ -1174,6 +1205,10 @@ void hrtimer_interrupt(struct clock_event_device *dev) 
	dev->next_event.tv64 = KTIME_MAX;



 retry:

	/* 5 retries is enough to notice a hang */

	if (!(++nr_retries % 5))

		hrtimer_interrupt_hanging(dev, ktime_sub(ktime_get(), now));



	now = ktime_get();



	expires_next.tv64 = KTIME_MAX;
@@ -1226,7 +1261,7 @@ void hrtimer_interrupt(struct clock_event_device *dev) 


	/* Reprogramming necessary ? */

	if (expires_next.tv64 != KTIME_MAX) {

		if (tick_program_event(expires_next, 0))

		if (tick_program_event(expires_next, force_clock_reprogram))

			goto retry;

	}

}
@@ -1580,6 +1615,10 @@ static int __cpuinit hrtimer_cpu_notify(struct notifier_block *self, 
		break;



#ifdef CONFIG_HOTPLUG_CPU

	case CPU_DYING:

	case CPU_DYING_FROZEN:

		clockevents_notify(CLOCK_EVT_NOTIFY_CPU_DYING, &scpu);

		break;

	case CPU_DEAD:

	case CPU_DEAD_FROZEN:

	{

kernel/time/tick-common.c

+19 −7
Original line number Diff line number Diff line
@@ -273,6 +273,21 @@ static int tick_check_new_device(struct clock_event_device *newdev) 
	return ret;

}



/*

 * Transfer the do_timer job away from a dying cpu.

 *

 * Called with interrupts disabled.

 */

static void tick_handover_do_timer(int *cpup)

{

	if (*cpup == tick_do_timer_cpu) {

		int cpu = cpumask_first(cpu_online_mask);



		tick_do_timer_cpu = (cpu < nr_cpu_ids) ? cpu :

			TICK_DO_TIMER_NONE;

	}

}



/*

 * Shutdown an event device on a given cpu:

 *
@@ -297,13 +312,6 @@ static void tick_shutdown(unsigned int *cpup) 
		clockevents_exchange_device(dev, NULL);

		td->evtdev = NULL;

	}

	/* Transfer the do_timer job away from this cpu */

	if (*cpup == tick_do_timer_cpu) {

		int cpu = cpumask_first(cpu_online_mask);



		tick_do_timer_cpu = (cpu < nr_cpu_ids) ? cpu :

			TICK_DO_TIMER_NONE;

	}

	spin_unlock_irqrestore(&tick_device_lock, flags);

}
@@ -357,6 +365,10 @@ static int tick_notify(struct notifier_block *nb, unsigned long reason, 
		tick_broadcast_oneshot_control(reason);

		break;



	case CLOCK_EVT_NOTIFY_CPU_DYING:

		tick_handover_do_timer(dev);

		break;



	case CLOCK_EVT_NOTIFY_CPU_DEAD:

		tick_shutdown_broadcast_oneshot(dev);

		tick_shutdown_broadcast(dev);