sched: Make hrtick_notifier an explicit call

No need for an extra notifier. We don't need to handle all these states. It's
sufficient to kill the timer when the cpu dies.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/20160310120025.770528462@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

kernel/sched/core.c

@@ -249,29 +249,6 @@ void hrtick_start(struct rq *rq, u64 delay)
 	}
 }
 
-static int
-hotplug_hrtick(struct notifier_block *nfb, unsigned long action, void *hcpu)
-{
-	int cpu = (int)(long)hcpu;
-
-	switch (action) {
-	case CPU_UP_CANCELED:
-	case CPU_UP_CANCELED_FROZEN:
-	case CPU_DOWN_PREPARE:
-	case CPU_DOWN_PREPARE_FROZEN:
-	case CPU_DEAD:
-	case CPU_DEAD_FROZEN:
-		hrtick_clear(cpu_rq(cpu));
-		return NOTIFY_OK;
-	}
-
-	return NOTIFY_DONE;
-}
-
-static __init void init_hrtick(void)
-{
-	hotcpu_notifier(hotplug_hrtick, 0);
-}
 #else
 /*
  * Called to set the hrtick timer state.
@@ -288,10 +265,6 @@ void hrtick_start(struct rq *rq, u64 delay)
 	hrtimer_start(&rq->hrtick_timer, ns_to_ktime(delay),
 		      HRTIMER_MODE_REL_PINNED);
 }
-
-static inline void init_hrtick(void)
-{
-}
 #endif /* CONFIG_SMP */
 
 static void init_rq_hrtick(struct rq *rq)
@@ -315,10 +288,6 @@ static inline void hrtick_clear(struct rq *rq)
 static inline void init_rq_hrtick(struct rq *rq)
 {
 }
-
-static inline void init_hrtick(void)
-{
-}
 #endif	/* CONFIG_SCHED_HRTICK */
 
 /*
@@ -7132,6 +7101,7 @@ int sched_cpu_dying(unsigned int cpu)
 	calc_load_migrate(rq);
 	update_max_interval();
 	nohz_balance_exit_idle(cpu);
+	hrtick_clear(rq);
 	return 0;
 }
 #endif
@@ -7157,8 +7127,6 @@ void __init sched_init_smp(void)
 		cpumask_set_cpu(smp_processor_id(), non_isolated_cpus);
 	mutex_unlock(&sched_domains_mutex);
 
-	init_hrtick();
-
 	/* Move init over to a non-isolated CPU */
 	if (set_cpus_allowed_ptr(current, non_isolated_cpus) < 0)
 		BUG();