From c65e5f6dee0aa259058487e8f2902617b8d5ef5e Mon Sep 17 00:00:00 2001
From: "Paul E. McKenney" <paul.mckenney@linaro.org>
Date: Wed, 11 Jan 2012 16:33:17 -0800
Subject: [PATCH] --- yaml --- r: 288559 b: refs/heads/master c:
 768dfffdffbfcc07d6927bdd642c714c0dd64c99 h: refs/heads/master i:   288557:
 e23dcf5233a9009a43008a1bcc6976bbe9467563   288555:
 40e91c27a62e67bc3ee592e4ee051f577e4656f5   288551:
 a84900cbe3824567a32b280a45f71c6e124e1d43   288543:
 a48f994e674cb9f04ad792cc7bf1e47fbed87c7e v: v3

---
 [refs]                        |  2 +-
 trunk/include/linux/rcutiny.h |  4 ----
 trunk/kernel/rcutiny_plugin.h | 15 ++++++++++++---
 3 files changed, 13 insertions(+), 8 deletions(-)

diff --git a/[refs] b/[refs]
index 793a83ac0c1a..9912994e0394 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: afef20540f7cd1ea91bc1ac20be238389eee4003
+refs/heads/master: 768dfffdffbfcc07d6927bdd642c714c0dd64c99
diff --git a/trunk/include/linux/rcutiny.h b/trunk/include/linux/rcutiny.h
index 51bf29c81485..e93df77176d1 100644
--- a/trunk/include/linux/rcutiny.h
+++ b/trunk/include/linux/rcutiny.h
@@ -27,13 +27,9 @@
 
 #include <linux/cache.h>
 
-#ifdef CONFIG_RCU_BOOST
 static inline void rcu_init(void)
 {
 }
-#else /* #ifdef CONFIG_RCU_BOOST */
-void rcu_init(void);
-#endif /* #else #ifdef CONFIG_RCU_BOOST */
 
 static inline void rcu_barrier_bh(void)
 {
diff --git a/trunk/kernel/rcutiny_plugin.h b/trunk/kernel/rcutiny_plugin.h
index b58a3200f0ff..95df60ebe363 100644
--- a/trunk/kernel/rcutiny_plugin.h
+++ b/trunk/kernel/rcutiny_plugin.h
@@ -914,7 +914,8 @@ static void rcu_preempt_process_callbacks(void)
 static void invoke_rcu_callbacks(void)
 {
 	have_rcu_kthread_work = 1;
-	wake_up(&rcu_kthread_wq);
+	if (rcu_kthread_task != NULL)
+		wake_up(&rcu_kthread_wq);
 }
 
 #ifdef CONFIG_RCU_TRACE
@@ -975,12 +976,16 @@ early_initcall(rcu_spawn_kthreads);
 
 #else /* #ifdef CONFIG_RCU_BOOST */
 
+/* Hold off callback invocation until early_initcall() time. */
+static int rcu_scheduler_fully_active __read_mostly;
+
 /*
  * Start up softirq processing of callbacks.
  */
 void invoke_rcu_callbacks(void)
 {
-	raise_softirq(RCU_SOFTIRQ);
+	if (rcu_scheduler_fully_active)
+		raise_softirq(RCU_SOFTIRQ);
 }
 
 #ifdef CONFIG_RCU_TRACE
@@ -995,10 +1000,14 @@ static bool rcu_is_callbacks_kthread(void)
 
 #endif /* #ifdef CONFIG_RCU_TRACE */
 
-void rcu_init(void)
+static int __init rcu_scheduler_really_started(void)
 {
+	rcu_scheduler_fully_active = 1;
 	open_softirq(RCU_SOFTIRQ, rcu_process_callbacks);
+	raise_softirq(RCU_SOFTIRQ);  /* Invoke any callbacks from early boot. */
+	return 0;
 }
+early_initcall(rcu_scheduler_really_started);
 
 #endif /* #else #ifdef CONFIG_RCU_BOOST */