1 files changed, 317 insertions, 17 deletions

diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index 24440f4bf476..83af1f8d8b74 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -40,6 +40,11 @@
 #include <linux/seqlock.h>
 #include <linux/lockdep.h>
 #include <linux/completion.h>
+#include <linux/debugobjects.h>
+
+#ifdef CONFIG_RCU_TORTURE_TEST
+extern int rcutorture_runnable; /* for sysctl */
+#endif /* #ifdef CONFIG_RCU_TORTURE_TEST */
 
 /**
  * struct rcu_head - callback structure for use with RCU
@@ -52,8 +57,6 @@ 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);
@@ -77,15 +80,215 @@ extern void rcu_init(void);
        (ptr)->next = NULL; (ptr)->func = NULL; \
 } while (0)
 
+/*
+ * init_rcu_head_on_stack()/destroy_rcu_head_on_stack() are needed for dynamic
+ * initialization and destruction of rcu_head on the stack. rcu_head structures
+ * allocated dynamically in the heap or defined statically don't need any
+ * initialization.
+ */
+#ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
+extern void init_rcu_head_on_stack(struct rcu_head *head);
+extern void destroy_rcu_head_on_stack(struct rcu_head *head);
+#else /* !CONFIG_DEBUG_OBJECTS_RCU_HEAD */
+static inline void init_rcu_head_on_stack(struct rcu_head *head)
+{
+}
+
+static inline void destroy_rcu_head_on_stack(struct rcu_head *head)
+{
+}
+#endif  /* #else !CONFIG_DEBUG_OBJECTS_RCU_HEAD */
+
 #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_)
+
+extern int debug_lockdep_rcu_enabled(void);
+
+/**
+ * rcu_read_lock_held - might we be in RCU read-side critical section?
+ *
+ * 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 debug_lockdep_rcu_enabled() to prevent false positives during boot
+ * and while lockdep is disabled.
+ */
+static inline int rcu_read_lock_held(void)
+{
+        if (!debug_lockdep_rcu_enabled())
+                return 1;
+        return lock_is_held(&rcu_lock_map);
+}
+
+/*
+ * rcu_read_lock_bh_held() is defined out of line to avoid #include-file
+ * hell.
+ */
+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_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 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)
+{
+        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 || irqs_disabled();
+}
+#else /* #ifdef CONFIG_PREEMPT */
+static inline int rcu_read_lock_sched_held(void)
+{
+        return 1;
+}
+#endif /* #else #ifdef CONFIG_PREEMPT */
+
+#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;
+}
+
+#ifdef CONFIG_PREEMPT
+static inline int rcu_read_lock_sched_held(void)
+{
+        return preempt_count() != 0 || irqs_disabled();
+}
+#else /* #ifdef CONFIG_PREEMPT */
+static inline int rcu_read_lock_sched_held(void)
+{
+        return 1;
+}
+#endif /* #else #ifdef CONFIG_PREEMPT */
+
+#endif /* #else #ifdef CONFIG_DEBUG_LOCK_ALLOC */
+
+#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
+ * @c: The conditions under which the dereference will take place
+ *
+ * Do an rcu_dereference(), but check that the conditions under which the
+ * dereference will take place are correct.  Typically the conditions indicate
+ * the various locking conditions that should be held at that point.  The check
+ * should return true if the conditions are satisfied.
+ *
+ * For example:
+ *
+ *      bar = rcu_dereference_check(foo->bar, rcu_read_lock_held() ||
+ *                                            lockdep_is_held(&foo->lock));
+ *
+ * could be used to indicate to lockdep that foo->bar may only be dereferenced
+ * if either the RCU read lock is held, or that the lock required to replace
+ * the bar struct at foo->bar is held.
+ *
+ * Note that the list of conditions may also include indications of when a lock
+ * need not be held, for example during initialisation or destruction of the
+ * target struct:
+ *
+ *      bar = rcu_dereference_check(foo->bar, rcu_read_lock_held() ||
+ *                                            lockdep_is_held(&foo->lock) ||
+ *                                            atomic_read(&foo->usage) == 0);
+ */
+#define rcu_dereference_check(p, c) \
+        ({ \
+                __do_rcu_dereference_check(c); \
+                rcu_dereference_raw(p); \
+        })
+
+/**
+ * rcu_dereference_protected - fetch RCU pointer when updates prevented
+ *
+ * Return the value of the specified RCU-protected pointer, but omit
+ * both the smp_read_barrier_depends() and the ACCESS_ONCE().  This
+ * is useful in cases where update-side locks prevent the value of the
+ * pointer from changing.  Please note that this primitive does -not-
+ * prevent the compiler from repeating this reference or combining it
+ * with other references, so it should not be used without protection
+ * of appropriate locks.
+ */
+#define rcu_dereference_protected(p, c) \
+        ({ \
+                __do_rcu_dereference_check(c); \
+                (p); \
+        })
+
+#else /* #ifdef CONFIG_PROVE_RCU */
+
+#define rcu_dereference_check(p, c)     rcu_dereference_raw(p)
+#define rcu_dereference_protected(p, c) (p)
+
+#endif /* #else #ifdef CONFIG_PROVE_RCU */
+
+/**
+ * rcu_access_pointer - fetch RCU pointer with no dereferencing
+ *
+ * Return the value of the specified RCU-protected pointer, but omit the
+ * smp_read_barrier_depends() and keep the ACCESS_ONCE().  This is useful
+ * when the value of this pointer is accessed, but the pointer is not
+ * dereferenced, for example, when testing an RCU-protected pointer against
+ * NULL.  This may also be used in cases where update-side locks prevent
+ * the value of the pointer from changing, but rcu_dereference_protected()
+ * is a lighter-weight primitive for this use case.
+ */
+#define rcu_access_pointer(p)   ACCESS_ONCE(p)
 
 /**
  * rcu_read_lock - mark the beginning of an RCU read-side critical section.
@@ -160,7 +363,7 @@ static inline void rcu_read_lock_bh(void)
 {
         __rcu_read_lock_bh();
         __acquire(RCU_BH);
-        rcu_read_acquire();
+        rcu_read_acquire_bh();
 }
 
 /*
@@ -170,7 +373,7 @@ 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 +391,7 @@ 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 +408,7 @@ 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();
 }
@@ -219,22 +422,49 @@ static inline notrace void rcu_read_unlock_sched_notrace(void)
 
 
 /**
- * rcu_dereference - fetch an RCU-protected pointer in an
- * RCU read-side critical section.  This pointer may later
- * be safely dereferenced.
+ * rcu_dereference_raw - fetch an RCU-protected pointer
+ *
+ * The caller must be within some flavor of RCU read-side critical
+ * section, or must be otherwise preventing the pointer from changing,
+ * for example, by holding an appropriate lock.  This pointer may later
+ * be safely dereferenced.  It is the caller's responsibility to have
+ * done the right thing, as this primitive does no checking of any kind.
  *
  * Inserts memory barriers on architectures that require them
  * (currently only the Alpha), and, more importantly, documents
  * exactly which pointers are protected by RCU.
  */
-
-#define rcu_dereference(p)     ({ \
+#define rcu_dereference_raw(p)  ({ \
                                 typeof(p) _________p1 = ACCESS_ONCE(p); \
                                 smp_read_barrier_depends(); \
                                 (_________p1); \
                                 })
 
 /**
+ * rcu_dereference - fetch an RCU-protected pointer, checking for RCU
+ *
+ * Makes rcu_dereference_check() do the dirty work.
+ */
+#define rcu_dereference(p) \
+        rcu_dereference_check(p, rcu_read_lock_held())
+
+/**
+ * rcu_dereference_bh - fetch an RCU-protected pointer, checking for RCU-bh
+ *
+ * Makes rcu_dereference_check() do the dirty work.
+ */
+#define rcu_dereference_bh(p) \
+                rcu_dereference_check(p, rcu_read_lock_bh_held() || irqs_disabled())
+
+/**
+ * rcu_dereference_sched - fetch RCU-protected pointer, checking for RCU-sched
+ *
+ * Makes rcu_dereference_check() do the dirty work.
+ */
+#define rcu_dereference_sched(p) \
+                rcu_dereference_check(p, rcu_read_lock_sched_held())
+
+/**
  * rcu_assign_pointer - assign (publicize) a pointer to a newly
  * initialized structure that will be dereferenced by RCU read-side
  * critical sections.  Returns the value assigned.
@@ -299,4 +529,74 @@ extern void call_rcu(struct rcu_head *head,
 extern void call_rcu_bh(struct rcu_head *head,
                         void (*func)(struct rcu_head *head));
 
+/*
+ * debug_rcu_head_queue()/debug_rcu_head_unqueue() are used internally
+ * by call_rcu() and rcu callback execution, and are therefore not part of the
+ * RCU API. Leaving in rcupdate.h because they are used by all RCU flavors.
+ */
+
+#ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
+# define STATE_RCU_HEAD_READY   0
+# define STATE_RCU_HEAD_QUEUED  1
+
+extern struct debug_obj_descr rcuhead_debug_descr;
+
+static inline void debug_rcu_head_queue(struct rcu_head *head)
+{
+        debug_object_activate(head, &rcuhead_debug_descr);
+        debug_object_active_state(head, &rcuhead_debug_descr,
+                                  STATE_RCU_HEAD_READY,
+                                  STATE_RCU_HEAD_QUEUED);
+}
+
+static inline void debug_rcu_head_unqueue(struct rcu_head *head)
+{
+        debug_object_active_state(head, &rcuhead_debug_descr,
+                                  STATE_RCU_HEAD_QUEUED,
+                                  STATE_RCU_HEAD_READY);
+        debug_object_deactivate(head, &rcuhead_debug_descr);
+}
+#else   /* !CONFIG_DEBUG_OBJECTS_RCU_HEAD */
+static inline void debug_rcu_head_queue(struct rcu_head *head)
+{
+}
+
+static inline void debug_rcu_head_unqueue(struct rcu_head *head)
+{
+}
+#endif  /* #else !CONFIG_DEBUG_OBJECTS_RCU_HEAD */
+
+#ifndef CONFIG_PROVE_RCU
+#define __do_rcu_dereference_check(c) do { } while (0)
+#endif /* #ifdef CONFIG_PROVE_RCU */
+
+#define __rcu_dereference_index_check(p, c) \
+        ({ \
+                typeof(p) _________p1 = ACCESS_ONCE(p); \
+                __do_rcu_dereference_check(c); \
+                smp_read_barrier_depends(); \
+                (_________p1); \
+        })
+
+/**
+ * rcu_dereference_index_check() - rcu_dereference for indices with debug checking
+ * @p: The pointer to read, prior to dereferencing
+ * @c: The conditions under which the dereference will take place
+ *
+ * Similar to rcu_dereference_check(), but omits the sparse checking.
+ * This allows rcu_dereference_index_check() to be used on integers,
+ * which can then be used as array indices.  Attempting to use
+ * rcu_dereference_check() on an integer will give compiler warnings
+ * because the sparse address-space mechanism relies on dereferencing
+ * the RCU-protected pointer.  Dereferencing integers is not something
+ * that even gcc will put up with.
+ *
+ * Note that this function does not implicitly check for RCU read-side
+ * critical sections.  If this function gains lots of uses, it might
+ * make sense to provide versions for each flavor of RCU, but it does
+ * not make sense as of early 2010.
+ */
+#define rcu_dereference_index_check(p, c) \
+        __rcu_dereference_index_check((p), (c))
+
 #endif /* __LINUX_RCUPDATE_H */