[tip:smp/hotplug] rcu: Make CPU_DYING_IDLE an explicit call

[tip-bot for Thomas Gleixner]

Commit-ID:  27d50c7eeb0f03c3d3ca72aac4d2dd487ca1f3f0
Gitweb:     http://git.kernel.org/tip/27d50c7eeb0f03c3d3ca72aac4d2dd487ca1f3f0
Author:     Thomas Gleixner <tglx@xxxxxxxxxxxxx>
AuthorDate: Fri, 26 Feb 2016 18:43:44 +0000
Committer:  Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitDate: Tue, 1 Mar 2016 20:36:58 +0100

rcu: Make CPU_DYING_IDLE an explicit call

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>
Cc: linux-arch@xxxxxxxxxxxxxxx
Cc: Rik van Riel <riel@xxxxxxxxxx>
Cc: Rafael Wysocki <rafael.j.wysocki@xxxxxxxxx>
Cc: "Srivatsa S. Bhat" <srivatsa@xxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Arjan van de Ven <arjan@xxxxxxxxxxxxxxx>
Cc: Sebastian Siewior <bigeasy@xxxxxxxxxxxxx>
Cc: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
Cc: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: Tejun Heo <tj@xxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Paul McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Paul Turner <pjt@xxxxxxxxxx>
Link: http://lkml.kernel.org/r/20160226182341.870167933@xxxxxxxxxxxxx
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        | 70 +++++++++++++++++++++++++-----------------------
 kernel/sched/idle.c      |  2 --
 6 files changed, 42 insertions(+), 41 deletions(-)

diff --git a/include/linux/cpu.h b/include/linux/cpu.h
index 91a48d1..f9b1fab 100644
--- 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
diff --git a/include/linux/notifier.h b/include/linux/notifier.h
index d14a4c3..4149868 100644
--- 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);
 
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index 14e6f47..fc46fe3 100644
--- 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);
diff --git a/kernel/cpu.c b/kernel/cpu.c
index 0e8c07f..ff8059b 100644
--- 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
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index e41dd41..85b4134 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -2607,28 +2607,6 @@ static void rcu_cleanup_dead_rnp(struct rcu_node *rnp_leaf)
 }
 
 /*
- * The CPU is exiting the idle loop into the arch_cpu_idle_dead()
- * function.  We now remove it from the rcu_node tree's ->qsmaskinit
- * bit masks.
- */
-static void rcu_cleanup_dying_idle_cpu(int cpu, struct rcu_state *rsp)
-{
-	unsigned long flags;
-	unsigned long mask;
-	struct rcu_data *rdp = per_cpu_ptr(rsp->rda, cpu);
-	struct rcu_node *rnp = rdp->mynode;  /* Outgoing CPU's rdp & rnp. */
-
-	if (!IS_ENABLED(CONFIG_HOTPLUG_CPU))
-		return;
-
-	/* Remove outgoing CPU from mask in the leaf rcu_node structure. */
-	mask = rdp->grpmask;
-	raw_spin_lock_irqsave_rcu_node(rnp, flags); /* Enforce GP memory-order guarantee. */
-	rnp->qsmaskinitnext &= ~mask;
-	raw_spin_unlock_irqrestore(&rnp->lock, flags);
-}
-
-/*
  * The CPU has been completely removed, and some other CPU is reporting
  * this fact from process context.  Do the remainder of the cleanup,
  * including orphaning the outgoing CPU's RCU callbacks, and also
@@ -4247,6 +4225,43 @@ static void rcu_prepare_cpu(int cpu)
 		rcu_init_percpu_data(cpu, rsp);
 }
 
+#ifdef CONFIG_HOTPLUG_CPU
+/*
+ * The CPU is exiting the idle loop into the arch_cpu_idle_dead()
+ * function.  We now remove it from the rcu_node tree's ->qsmaskinit
+ * bit masks.
+ */
+static void rcu_cleanup_dying_idle_cpu(int cpu, struct rcu_state *rsp)
+{
+	unsigned long flags;
+	unsigned long mask;
+	struct rcu_data *rdp = per_cpu_ptr(rsp->rda, cpu);
+	struct rcu_node *rnp = rdp->mynode;  /* Outgoing CPU's rdp & rnp. */
+
+	if (!IS_ENABLED(CONFIG_HOTPLUG_CPU))
+		return;
+
+	/* Remove outgoing CPU from mask in the leaf rcu_node structure. */
+	mask = rdp->grpmask;
+	raw_spin_lock_irqsave_rcu_node(rnp, flags); /* Enforce GP memory-order guarantee. */
+	rnp->qsmaskinitnext &= ~mask;
+	raw_spin_unlock_irqrestore(&rnp->lock, flags);
+}
+
+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 *self,
 		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:
diff --git a/kernel/sched/idle.c b/kernel/sched/idle.c
index 8abbe89..bd12c6c 100644
--- 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();
 			}