[patch 20/20] rcu: Make CPU_DYING_IDLE an explicit call

[Thomas Gleixner]

Make the RCU CPU_DYING_IDLE callback an explicit function call, so it gets
invoked at the proper place.

Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
---
 include/linux/cpu.h      |    4 +---
 include/linux/notifier.h |    2 ++
 include/linux/rcupdate.h |    4 +---
 kernel/cpu.c             |    1 +
 kernel/rcu/tree.c        |   26 +++++++++++++++-----------
 kernel/sched/idle.c      |    2 --
 6 files changed, 20 insertions(+), 19 deletions(-)

Index: b/include/linux/cpu.h
===================================================================
--- a/include/linux/cpu.h
+++ b/include/linux/cpu.h
@@ -101,9 +101,7 @@ enum {
 					* Called on the new cpu, just before
 					* enabling interrupts. Must not sleep,
 					* must not fail */
-#define CPU_DYING_IDLE		0x000B /* CPU (unsigned)v dying, reached
-					* idle loop. */
-#define CPU_BROKEN		0x000C /* CPU (unsigned)v did not die properly,
+#define CPU_BROKEN		0x000B /* CPU (unsigned)v did not die properly,
 					* perhaps due to preemption. */
 
 /* Used for CPU hotplug events occurring while tasks are frozen due to a suspend
Index: b/include/linux/notifier.h
===================================================================
--- a/include/linux/notifier.h
+++ b/include/linux/notifier.h
@@ -47,6 +47,8 @@
  * runtime initialization.
  */
 
+struct notifier_block;
+
 typedef	int (*notifier_fn_t)(struct notifier_block *nb,
 			unsigned long action, void *data);
 
Index: b/include/linux/rcupdate.h
===================================================================
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -332,9 +332,7 @@ void rcu_init(void);
 void rcu_sched_qs(void);
 void rcu_bh_qs(void);
 void rcu_check_callbacks(int user);
-struct notifier_block;
-int rcu_cpu_notify(struct notifier_block *self,
-		   unsigned long action, void *hcpu);
+void rcu_report_dead(unsigned int cpu);
 
 #ifndef CONFIG_TINY_RCU
 void rcu_end_inkernel_boot(void);
Index: b/kernel/cpu.c
===================================================================
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -762,6 +762,7 @@ void cpuhp_report_idle_dead(void)
 	BUG_ON(st->state != CPUHP_AP_OFFLINE);
 	st->state = CPUHP_AP_IDLE_DEAD;
 	complete(&st->done);
+	rcu_report_dead(smp_processor_id());
 }
 
 #else
Index: b/kernel/rcu/tree.c
===================================================================
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -4247,6 +4247,21 @@ static void rcu_prepare_cpu(int cpu)
 		rcu_init_percpu_data(cpu, rsp);
 }
 
+#ifdef CONFIG_HOTPLUG_CPU
+void rcu_report_dead(unsigned int cpu)
+{
+	struct rcu_state *rsp;
+
+	/* QS for any half-done expedited RCU-sched GP. */
+	preempt_disable();
+	rcu_report_exp_rdp(&rcu_sched_state,
+			   this_cpu_ptr(rcu_sched_state.rda), true);
+	preempt_enable();
+	for_each_rcu_flavor(rsp)
+		rcu_cleanup_dying_idle_cpu(cpu, rsp);
+}
+#endif
+
 /*
  * Handle CPU online/offline notification events.
  */
@@ -4278,17 +4293,6 @@ int rcu_cpu_notify(struct notifier_block
 		for_each_rcu_flavor(rsp)
 			rcu_cleanup_dying_cpu(rsp);
 		break;
-	case CPU_DYING_IDLE:
-		/* QS for any half-done expedited RCU-sched GP. */
-		preempt_disable();
-		rcu_report_exp_rdp(&rcu_sched_state,
-				   this_cpu_ptr(rcu_sched_state.rda), true);
-		preempt_enable();
-
-		for_each_rcu_flavor(rsp) {
-			rcu_cleanup_dying_idle_cpu(cpu, rsp);
-		}
-		break;
 	case CPU_DEAD:
 	case CPU_DEAD_FROZEN:
 	case CPU_UP_CANCELED:
Index: b/kernel/sched/idle.c
===================================================================
--- a/kernel/sched/idle.c
+++ b/kernel/sched/idle.c
@@ -220,8 +220,6 @@ static void cpu_idle_loop(void)
 			rmb();
 
 			if (cpu_is_offline(smp_processor_id())) {
-				rcu_cpu_notify(NULL, CPU_DYING_IDLE,
-					       (void *)(long)smp_processor_id());
 				cpuhp_report_idle_dead();
 				arch_cpu_idle_dead();
 			}