migrate_timers: add comment, use spinlock_irq()

	new_base = &get_cpu_var(hrtimer_bases);

	tick_cancel_sched_timer(cpu);

	local_irq_disable();

	spin_lock(&new_base->lock);

	/*

	 * The caller is globally serialized and nobody else

	 * takes two locks at once, deadlock is not possible.

	 */

	spin_lock_irq(&new_base->lock);

	spin_lock_nested(&old_base->lock, SINGLE_DEPTH_NESTING);

	for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++) {

	}

	spin_unlock(&old_base->lock);

	spin_unlock(&new_base->lock);

	local_irq_enable();

	spin_unlock_irq(&new_base->lock);

	put_cpu_var(hrtimer_bases);

}

#endif /* CONFIG_HOTPLUG_CPU */

	BUG_ON(cpu_online(cpu));

	old_base = per_cpu(tvec_bases, cpu);

	new_base = get_cpu_var(tvec_bases);

	local_irq_disable();

	spin_lock(&new_base->lock);

	/*

	 * The caller is globally serialized and nobody else

	 * takes two locks at once, deadlock is not possible.

	 */

	spin_lock_irq(&new_base->lock);

	spin_lock_nested(&old_base->lock, SINGLE_DEPTH_NESTING);

	BUG_ON(old_base->running_timer);

	}

	spin_unlock(&old_base->lock);

	spin_unlock(&new_base->lock);

	local_irq_enable();

	spin_unlock_irq(&new_base->lock);

	put_cpu_var(tvec_bases);

}

#endif /* CONFIG_HOTPLUG_CPU */