1 files changed, 34 insertions, 18 deletions

diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index 07db2feb8572..b653b4aaa8a6 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -56,8 +56,6 @@ struct rcu_head {
 };
 
 /* Exported common interfaces */
-extern void synchronize_rcu_bh(void);
-extern void synchronize_sched(void);
 extern void rcu_barrier(void);
 extern void rcu_barrier_bh(void);
 extern void rcu_barrier_sched(void);
@@ -66,8 +64,6 @@ extern int sched_expedited_torture_stats(char *page);
 
 /* Internal to kernel */
 extern void rcu_init(void);
-extern int rcu_scheduler_active;
-extern void rcu_scheduler_starting(void);
 
 #if defined(CONFIG_TREE_RCU) || defined(CONFIG_TREE_PREEMPT_RCU)
 #include <linux/rcutree.h>
@@ -83,6 +79,14 @@ extern void rcu_scheduler_starting(void);
        (ptr)->next = NULL; (ptr)->func = NULL; \
 } while (0)
 
+static inline void init_rcu_head_on_stack(struct rcu_head *head)
+{
+}
+
+static inline void destroy_rcu_head_on_stack(struct rcu_head *head)
+{
+}
+
 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 
 extern struct lockdep_map rcu_lock_map;
@@ -106,12 +110,13 @@ extern int debug_lockdep_rcu_enabled(void);
 /**
  * rcu_read_lock_held - might we be in RCU read-side critical section?
  *
- * If CONFIG_PROVE_LOCKING is selected and enabled, returns nonzero iff in
- * an RCU read-side critical section.  In absence of CONFIG_PROVE_LOCKING,
+ * If CONFIG_DEBUG_LOCK_ALLOC is selected, returns nonzero iff in an RCU
+ * read-side critical section.  In absence of CONFIG_DEBUG_LOCK_ALLOC,
  * 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.
+ * Check debug_lockdep_rcu_enabled() to prevent false positives during boot
+ * and while lockdep is disabled.
  */
 static inline int rcu_read_lock_held(void)
 {
@@ -129,13 +134,15 @@ extern int rcu_read_lock_bh_held(void);
 /**
  * rcu_read_lock_sched_held - might we be in RCU-sched read-side critical section?
  *
- * If CONFIG_PROVE_LOCKING is selected and enabled, returns nonzero iff in an
- * RCU-sched read-side critical section.  In absence of CONFIG_PROVE_LOCKING,
- * 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.
+ * If CONFIG_DEBUG_LOCK_ALLOC is selected, returns nonzero iff in an
+ * RCU-sched read-side critical section.  In absence of
+ * CONFIG_DEBUG_LOCK_ALLOC, 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.
+ * Check debug_lockdep_rcu_enabled() to prevent false positives during boot
+ * and while lockdep is disabled.
  */
 #ifdef CONFIG_PREEMPT
 static inline int rcu_read_lock_sched_held(void)
@@ -177,7 +184,7 @@ static inline int rcu_read_lock_bh_held(void)
 #ifdef CONFIG_PREEMPT
 static inline int rcu_read_lock_sched_held(void)
 {
-        return !rcu_scheduler_active || preempt_count() != 0 || irqs_disabled();
+        return preempt_count() != 0 || irqs_disabled();
 }
 #else /* #ifdef CONFIG_PREEMPT */
 static inline int rcu_read_lock_sched_held(void)
@@ -190,6 +197,17 @@ static inline int rcu_read_lock_sched_held(void)
 
 #ifdef CONFIG_PROVE_RCU
 
+extern int rcu_my_thread_group_empty(void);
+
+#define __do_rcu_dereference_check(c)                                   \
+        do {                                                            \
+                static bool __warned;                                   \
+                if (debug_lockdep_rcu_enabled() && !__warned && !(c)) { \
+                        __warned = true;                                \
+                        lockdep_rcu_dereference(__FILE__, __LINE__);    \
+                }                                                       \
+        } while (0)
+
 /**
  * rcu_dereference_check - rcu_dereference with debug checking
  * @p: The pointer to read, prior to dereferencing
@@ -219,8 +237,7 @@ static inline int rcu_read_lock_sched_held(void)
  */
 #define rcu_dereference_check(p, c) \
         ({ \
-                if (debug_lockdep_rcu_enabled() && !(c)) \
-                        lockdep_rcu_dereference(__FILE__, __LINE__); \
+                __do_rcu_dereference_check(c); \
                 rcu_dereference_raw(p); \
         })
 
@@ -237,8 +254,7 @@ static inline int rcu_read_lock_sched_held(void)
  */
 #define rcu_dereference_protected(p, c) \
         ({ \
-                if (debug_lockdep_rcu_enabled() && !(c)) \
-                        lockdep_rcu_dereference(__FILE__, __LINE__); \
+                __do_rcu_dereference_check(c); \
                 (p); \
         })