1 files changed, 19 insertions, 18 deletions

diff --git a/kernel/cpu.c b/kernel/cpu.c
index b03a32595cfe..ab860453841d 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -271,11 +271,25 @@ void cpu_hotplug_enable(void)
 EXPORT_SYMBOL_GPL(cpu_hotplug_enable);
 #endif	/* CONFIG_HOTPLUG_CPU */
 
+static void __cpuhp_kick_ap_work(struct cpuhp_cpu_state *st);
+
 static int bringup_wait_for_ap(unsigned int cpu)
 {
 	struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
 
+	/* Wait for the CPU to reach CPUHP_AP_ONLINE_IDLE */
 	wait_for_completion(&st->done);
+	BUG_ON(!cpu_online(cpu));
+
+	/* Unpark the stopper thread and the hotplug thread of the target cpu */
+	stop_machine_unpark(cpu);
+	kthread_unpark(st->thread);
+
+	/* Should we go further up ? */
+	if (st->target > CPUHP_AP_ONLINE_IDLE) {
+		__cpuhp_kick_ap_work(st);
+		wait_for_completion(&st->done);
+	}
 	return st->result;
 }
 
@@ -296,9 +310,7 @@ static int bringup_cpu(unsigned int cpu)
 	irq_unlock_sparse();
 	if (ret)
 		return ret;
-	ret = bringup_wait_for_ap(cpu);
-	BUG_ON(!cpu_online(cpu));
-	return ret;
+	return bringup_wait_for_ap(cpu);
 }
 
 /*
@@ -767,31 +779,20 @@ void notify_cpu_starting(unsigned int cpu)
 }
 
 /*
- * Called from the idle task. We need to set active here, so we can kick off
- * the stopper thread and unpark the smpboot threads. If the target state is
- * beyond CPUHP_AP_ONLINE_IDLE we kick cpuhp thread and let it bring up the
- * cpu further.
+ * Called from the idle task. Wake up the controlling task which brings the
+ * stopper and the hotplug thread of the upcoming CPU up and then delegates
+ * the rest of the online bringup to the hotplug thread.
  */
 void cpuhp_online_idle(enum cpuhp_state state)
 {
 	struct cpuhp_cpu_state *st = this_cpu_ptr(&cpuhp_state);
-	unsigned int cpu = smp_processor_id();
 
 	/* Happens for the boot cpu */
 	if (state != CPUHP_AP_ONLINE_IDLE)
 		return;
 
 	st->state = CPUHP_AP_ONLINE_IDLE;
-
-	/* Unpark the stopper thread and the hotplug thread of this cpu */
-	stop_machine_unpark(cpu);
-	kthread_unpark(st->thread);
-
-	/* Should we go further up ? */
-	if (st->target > CPUHP_AP_ONLINE_IDLE)
-		__cpuhp_kick_ap_work(st);
-	else
-		complete(&st->done);
+	complete(&st->done);
 }
 
 /* Requires cpu_add_remove_lock to be held */