From 2f1636de4acca37664513a1810361ea639692dee Mon Sep 17 00:00:00 2001
From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Date: Wed, 3 Mar 2010 07:46:57 -0800
Subject: [PATCH] --- yaml --- r: 187887 b: refs/heads/master c:
 54dbf96c921513bf98484a20ef366d51944a4c4d h: refs/heads/master i:   187885:
 b1ebe582dc1e8826cf24eb727b01629036e61f63   187883:
 e480fe954c583d72810116a49b46a600a8f48d3f   187879:
 a2b4e68a352d9fec53b105fe2e29fdb33f03bb42   187871:
 f5ebde96ef37c22fa93cd4a0ffbb8c4d3a20b38a v: v3

---
 [refs]                         |  2 +-
 trunk/include/linux/rcupdate.h | 31 ++++++++++++++++++++++---------
 2 files changed, 23 insertions(+), 10 deletions(-)

diff --git a/[refs] b/[refs]
index 68fc4e6b399f..eb564ecfabd2 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 8d53dd546f36073e0d29b0cfc24c665db301e3e7
+refs/heads/master: 54dbf96c921513bf98484a20ef366d51944a4c4d
diff --git a/trunk/include/linux/rcupdate.h b/trunk/include/linux/rcupdate.h
index e22960ecb71a..75921b83c0ab 100644
--- a/trunk/include/linux/rcupdate.h
+++ b/trunk/include/linux/rcupdate.h
@@ -97,6 +97,11 @@ extern struct lockdep_map rcu_sched_lock_map;
 # define rcu_read_release_sched() \
 		lock_release(&rcu_sched_lock_map, 1, _THIS_IP_)
 
+static inline int debug_lockdep_rcu_enabled(void)
+{
+	return likely(rcu_scheduler_active && debug_locks);
+}
+
 /**
  * rcu_read_lock_held - might we be in RCU read-side critical section?
  *
@@ -104,12 +109,14 @@ extern struct lockdep_map rcu_sched_lock_map;
  * an RCU read-side critical section.  In absence of CONFIG_PROVE_LOCKING,
  * this assumes we are in an RCU read-side critical section unless it can
  * prove otherwise.
+ *
+ * Check rcu_scheduler_active to prevent false positives during boot.
  */
 static inline int rcu_read_lock_held(void)
 {
-	if (debug_locks)
-		return lock_is_held(&rcu_lock_map);
-	return 1;
+	if (!debug_lockdep_rcu_enabled())
+		return 1;
+	return lock_is_held(&rcu_lock_map);
 }
 
 /**
@@ -119,12 +126,14 @@ static inline int rcu_read_lock_held(void)
  * an RCU-bh read-side critical section.  In absence of CONFIG_PROVE_LOCKING,
  * this assumes we are in an RCU-bh read-side critical section unless it can
  * prove otherwise.
+ *
+ * Check rcu_scheduler_active to prevent false positives during boot.
  */
 static inline int rcu_read_lock_bh_held(void)
 {
-	if (debug_locks)
-		return lock_is_held(&rcu_bh_lock_map);
-	return 1;
+	if (!debug_lockdep_rcu_enabled())
+		return 1;
+	return lock_is_held(&rcu_bh_lock_map);
 }
 
 /**
@@ -135,15 +144,19 @@ static inline int rcu_read_lock_bh_held(void)
  * this assumes we are in an RCU-sched read-side critical section unless it
  * can prove otherwise.  Note that disabling of preemption (including
  * disabling irqs) counts as an RCU-sched read-side critical section.
+ *
+ * Check rcu_scheduler_active to prevent false positives during boot.
  */
 #ifdef CONFIG_PREEMPT
 static inline int rcu_read_lock_sched_held(void)
 {
 	int lockdep_opinion = 0;
 
+	if (!debug_lockdep_rcu_enabled())
+		return 1;
 	if (debug_locks)
 		lockdep_opinion = lock_is_held(&rcu_sched_lock_map);
-	return lockdep_opinion || preempt_count() != 0 || !rcu_scheduler_active;
+	return lockdep_opinion || preempt_count() != 0;
 }
 #else /* #ifdef CONFIG_PREEMPT */
 static inline int rcu_read_lock_sched_held(void)
@@ -174,7 +187,7 @@ static inline int rcu_read_lock_bh_held(void)
 #ifdef CONFIG_PREEMPT
 static inline int rcu_read_lock_sched_held(void)
 {
-	return preempt_count() != 0 || !rcu_scheduler_active;
+	return !rcu_scheduler_active || preempt_count() != 0;
 }
 #else /* #ifdef CONFIG_PREEMPT */
 static inline int rcu_read_lock_sched_held(void)
@@ -198,7 +211,7 @@ static inline int rcu_read_lock_sched_held(void)
  */
 #define rcu_dereference_check(p, c) \
 	({ \
-		if (debug_locks && !(c)) \
+		if (debug_lockdep_rcu_enabled() && !(c)) \
 			lockdep_rcu_dereference(__FILE__, __LINE__); \
 		rcu_dereference_raw(p); \
 	})