rcu: Introduce lockdep-based checking to RCU read-side primitives

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

diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index 24440f4..e3d37ef 100644 (file)
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -78,14 +78,120 @@ extern void rcu_init(void);
 } while (0)
 
 #ifdef CONFIG_DEBUG_LOCK_ALLOC
+
 extern struct lockdep_map rcu_lock_map;
-# define rcu_read_acquire()    \
-                       lock_acquire(&rcu_lock_map, 0, 0, 2, 1, NULL, _THIS_IP_)
+# define rcu_read_acquire() \
+               lock_acquire(&rcu_lock_map, 0, 0, 2, 1, NULL, _THIS_IP_)
 # define rcu_read_release()    lock_release(&rcu_lock_map, 1, _THIS_IP_)
-#else
-# define rcu_read_acquire()    do { } while (0)
-# define rcu_read_release()    do { } while (0)
-#endif
+
+extern struct lockdep_map rcu_bh_lock_map;
+# define rcu_read_acquire_bh() \
+               lock_acquire(&rcu_bh_lock_map, 0, 0, 2, 1, NULL, _THIS_IP_)
+# define rcu_read_release_bh() lock_release(&rcu_bh_lock_map, 1, _THIS_IP_)
+
+extern struct lockdep_map rcu_sched_lock_map;
+# define rcu_read_acquire_sched() \
+               lock_acquire(&rcu_sched_lock_map, 0, 0, 2, 1, NULL, _THIS_IP_)
+# define rcu_read_release_sched() \
+               lock_release(&rcu_sched_lock_map, 1, _THIS_IP_)
+
+/**
+ * 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,
+ * this assumes we are in an RCU read-side critical section unless it can
+ * prove otherwise.
+ */
+static inline int rcu_read_lock_held(void)
+{
+       if (debug_locks)
+               return lock_is_held(&rcu_lock_map);
+       return 1;
+}
+
+/**
+ * rcu_read_lock_bh_held - might we be in RCU-bh read-side critical section?
+ *
+ * If CONFIG_PROVE_LOCKING is selected and enabled, returns nonzero iff in
+ * 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.
+ */
+static inline int rcu_read_lock_bh_held(void)
+{
+       if (debug_locks)
+               return lock_is_held(&rcu_bh_lock_map);
+       return 1;
+}
+
+/**
+ * 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.
+ */
+static inline int rcu_read_lock_sched_held(void)
+{
+       int lockdep_opinion = 0;
+
+       if (debug_locks)
+               lockdep_opinion = lock_is_held(&rcu_sched_lock_map);
+       return lockdep_opinion || preempt_count() != 0;
+}
+
+#else /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */
+
+# define rcu_read_acquire()            do { } while (0)
+# define rcu_read_release()            do { } while (0)
+# define rcu_read_acquire_bh()         do { } while (0)
+# define rcu_read_release_bh()         do { } while (0)
+# define rcu_read_acquire_sched()      do { } while (0)
+# define rcu_read_release_sched()      do { } while (0)
+
+static inline int rcu_read_lock_held(void)
+{
+       return 1;
+}
+
+static inline int rcu_read_lock_bh_held(void)
+{
+       return 1;
+}
+
+static inline int rcu_read_lock_sched_held(void)
+{
+       return preempt_count() != 0;
+}
+
+#endif /* #else #ifdef CONFIG_DEBUG_LOCK_ALLOC */
+
+#ifdef CONFIG_PROVE_RCU
+
+/**
+ * rcu_dereference_check - rcu_dereference with debug checking
+ *
+ * Do an rcu_dereference(), but check that the context is correct.
+ * For example, rcu_dereference_check(gp, rcu_read_lock_held()) to
+ * ensure that the rcu_dereference_check() executes within an RCU
+ * read-side critical section.  It is also possible to check for
+ * locks being held, for example, by using lockdep_is_held().
+ */
+#define rcu_dereference_check(p, c) \
+       ({ \
+               if (debug_locks) \
+                       WARN_ON_ONCE(!(c)); \
+               rcu_dereference(p); \
+       })
+
+#else /* #ifdef CONFIG_PROVE_RCU */
+
+#define rcu_dereference_check(p, c)    rcu_dereference(p)
+
+#endif /* #else #ifdef CONFIG_PROVE_RCU */
 
 /**
  * rcu_read_lock - mark the beginning of an RCU read-side critical section.
@@ -160,7 +266,7 @@ static inline void rcu_read_lock_bh(void)
 {
        __rcu_read_lock_bh();
        __acquire(RCU_BH);
-       rcu_read_acquire();
+       rcu_read_acquire_bh();
 }
 
 /*
@@ -170,7 +276,7 @@ static inline void rcu_read_lock_bh(void)
  */
 static inline void rcu_read_unlock_bh(void)
 {
-       rcu_read_release();
+       rcu_read_release_bh();
        __release(RCU_BH);
        __rcu_read_unlock_bh();
 }
@@ -188,7 +294,7 @@ static inline void rcu_read_lock_sched(void)
 {
        preempt_disable();
        __acquire(RCU_SCHED);
-       rcu_read_acquire();
+       rcu_read_acquire_sched();
 }
 
 /* Used by lockdep and tracing: cannot be traced, cannot call lockdep. */
@@ -205,7 +311,7 @@ static inline notrace void rcu_read_lock_sched_notrace(void)
  */
 static inline void rcu_read_unlock_sched(void)
 {
-       rcu_read_release();
+       rcu_read_release_sched();
        __release(RCU_SCHED);
        preempt_enable();
 }