rcu: optionally leave lockdep enabled after RCU lockdep splat

[safe/jmp/linux-2.6] / include / linux / rcupdate.h

diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index db266bb..4dca275 100644 (file)
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -192,6 +192,15 @@ static inline int rcu_read_lock_sched_held(void)
 
 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
@@ -221,8 +230,7 @@ extern int rcu_my_thread_group_empty(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); \
        })
 
@@ -239,8 +247,7 @@ extern int rcu_my_thread_group_empty(void);
  */
 #define rcu_dereference_protected(p, c) \
        ({ \
-               if (debug_lockdep_rcu_enabled() && !(c)) \
-                       lockdep_rcu_dereference(__FILE__, __LINE__); \
+               __do_rcu_dereference_check(c); \
                (p); \
        })