#include <linux/lockdep.h>
#include <linux/completion.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
* @next: next update requests in a list
/* 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>
} 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_)
+
+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,
+ * 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_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_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.
+ *
+ * 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 || 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 !rcu_scheduler_active || 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);
+
+/**
+ * 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) \
+ ({ \
+ if (debug_lockdep_rcu_enabled() && !(c)) \
+ lockdep_rcu_dereference(__FILE__, __LINE__); \
+ 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) \
+ ({ \
+ if (debug_lockdep_rcu_enabled() && !(c)) \
+ lockdep_rcu_dereference(__FILE__, __LINE__); \
+ (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.
{
__rcu_read_lock_bh();
__acquire(RCU_BH);
- rcu_read_acquire();
+ rcu_read_acquire_bh();
}
/*
*/
static inline void rcu_read_unlock_bh(void)
{
- rcu_read_release();
+ rcu_read_release_bh();
__release(RCU_BH);
__rcu_read_unlock_bh();
}
{
preempt_disable();
__acquire(RCU_SCHED);
- rcu_read_acquire();
+ rcu_read_acquire_sched();
}
/* Used by lockdep and tracing: cannot be traced, cannot call lockdep. */
*/
static inline void rcu_read_unlock_sched(void)
{
- rcu_read_release();
+ rcu_read_release_sched();
__release(RCU_SCHED);
preempt_enable();
}
/**
- * 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())
+
+/**
+ * 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
projects / mirror_ubuntu-artful-kernel.git / blobdiff