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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

kernel/hrtimer.c

+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