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Commit 37810659 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
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hrtimer: removing all ur callback modes, fix hotplug



Impact: fix hrtimer locking (reported by lockdep) in the CPU hotplug case

This addition fixes the hotplug locking issue on my machine

Signed-off-by: default avatarPeter Zijlstra <peterz@infradead.org>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent ca109491
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+37 −28
Original line number Diff line number Diff line
@@ -1496,7 +1496,7 @@ static void __cpuinit init_hrtimers_cpu(int cpu)
#ifdef CONFIG_HOTPLUG_CPU

static void migrate_hrtimer_list(struct hrtimer_clock_base *old_base,
				 struct hrtimer_clock_base *new_base, int dcpu)
				struct hrtimer_clock_base *new_base)
{
	struct hrtimer *timer;
	struct rb_node *node;
@@ -1514,40 +1514,34 @@ static void migrate_hrtimer_list(struct hrtimer_clock_base *old_base,
		__remove_hrtimer(timer, old_base, HRTIMER_STATE_MIGRATE, 0);
		timer->base = new_base;
		/*
		 * Enqueue the timer. Allow reprogramming of the event device
		 * Enqueue the timers on the new cpu, but do not reprogram 
		 * the timer as that would enable a deadlock between
		 * hrtimer_enqueue_reprogramm() running the timer and us still
		 * holding a nested base lock.
		 *
		 * Instead we tickle the hrtimer interrupt after the migration
		 * is done, which will run all expired timers and re-programm
		 * the timer device.
		 */
		enqueue_hrtimer(timer, new_base, 1);
		enqueue_hrtimer(timer, new_base, 0);

#ifdef CONFIG_HIGH_RES_TIMERS
		/*
		 * Happens with high res enabled when the timer was
		 * already expired and the callback mode is
		 * HRTIMER_CB_IRQSAFE_UNLOCKED (hrtimer_sleeper). The
		 * enqueue code does not move them to the soft irq
		 * pending list for performance/latency reasons, but
		 * in the migration state, we need to do that
		 * otherwise we end up with a stale timer.
		 */
		if (timer->state == HRTIMER_STATE_MIGRATE) {
			/* XXX: running on offline cpu */
			__run_hrtimer(timer);
		}
#endif
		/* Clear the migration state bit */
		timer->state &= ~HRTIMER_STATE_MIGRATE;
	}
}

static void migrate_hrtimers(int cpu)
static int migrate_hrtimers(int scpu)
{
	struct hrtimer_cpu_base *old_base, *new_base;
	int i;
	int dcpu, i;

	BUG_ON(cpu_online(cpu));
	old_base = &per_cpu(hrtimer_bases, cpu);
	BUG_ON(cpu_online(scpu));
	old_base = &per_cpu(hrtimer_bases, scpu);
	new_base = &get_cpu_var(hrtimer_bases);

	tick_cancel_sched_timer(cpu);
	dcpu = smp_processor_id();

	tick_cancel_sched_timer(scpu);
	/*
	 * The caller is globally serialized and nobody else
	 * takes two locks at once, deadlock is not possible.
@@ -1557,32 +1551,47 @@ static void migrate_hrtimers(int cpu)

	for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++) {
		migrate_hrtimer_list(&old_base->clock_base[i],
				     &new_base->clock_base[i], cpu);
				     &new_base->clock_base[i]);
	}

	spin_unlock(&old_base->lock);
	spin_unlock_irq(&new_base->lock);
	put_cpu_var(hrtimer_bases);

	return dcpu;
}

static void tickle_timers(void *arg)
{
	hrtimer_peek_ahead_timers();
}

#endif /* CONFIG_HOTPLUG_CPU */

static int __cpuinit hrtimer_cpu_notify(struct notifier_block *self,
					unsigned long action, void *hcpu)
{
	unsigned int cpu = (long)hcpu;
	int dcpu = -1, scpu = (long)hcpu;

	switch (action) {

	case CPU_UP_PREPARE:
	case CPU_UP_PREPARE_FROZEN:
		init_hrtimers_cpu(cpu);
		init_hrtimers_cpu(scpu);
		break;

#ifdef CONFIG_HOTPLUG_CPU
	case CPU_DEAD:
	case CPU_DEAD_FROZEN:
		clockevents_notify(CLOCK_EVT_NOTIFY_CPU_DEAD, &cpu);
		migrate_hrtimers(cpu);
		clockevents_notify(CLOCK_EVT_NOTIFY_CPU_DEAD, &scpu);
		dcpu = migrate_hrtimers(scpu);
		break;

	case CPU_POST_DEAD:
		if (dcpu == -1)
			break;

		smp_call_function_single(dcpu, tickle_timers, NULL, 0);
		break;
#endif