#include <syscall.h>
#include <unistd.h>
-#include <compiler.h>
-#include <arch.h>
+#include <urcu/compiler.h>
+#include <urcu/arch.h>
+#include <urcu/system.h>
+#include <urcu/uatomic_arch.h>
+#include <urcu/list.h>
+#include <urcu/urcu-futex.h>
-/*
- * Identify a shared load. A smp_rmc() or smp_mc() should come before the load.
- */
-#define _LOAD_SHARED(p) ACCESS_ONCE(p)
-
-/*
- * Load a data from shared memory, doing a cache flush if required.
- */
-#define LOAD_SHARED(p) \
- ({ \
- smp_rmc(); \
- _LOAD_SHARED(p); \
- })
-
-/*
- * Identify a shared store. A smp_wmc() or smp_mc() should follow the store.
- */
-#define _STORE_SHARED(x, v) ({ ACCESS_ONCE(x) = (v); })
-
-/*
- * Store v into x, where x is located in shared memory. Performs the required
- * cache flush after writing. Returns v.
- */
-#define STORE_SHARED(x, v) \
- ({ \
- _STORE_SHARED(x, v); \
- smp_wmc(); \
- (v); \
- })
-
-/**
- * _rcu_dereference - reads (copy) a RCU-protected pointer to a local variable
- * into a RCU read-side critical section. The pointer can later be safely
- * dereferenced within the critical section.
- *
- * This ensures that the pointer copy is invariant thorough the whole critical
- * section.
- *
- * Inserts memory barriers on architectures that require them (currently only
- * Alpha) and documents which pointers are protected by RCU.
- *
- * The compiler memory barrier in LOAD_SHARED() ensures that value-speculative
- * optimizations (e.g. VSS: Value Speculation Scheduling) does not perform the
- * data read before the pointer read by speculating the value of the pointer.
- * Correct ordering is ensured because the pointer is read as a volatile access.
- * This acts as a global side-effect operation, which forbids reordering of
- * dependent memory operations. Note that such concern about dependency-breaking
- * optimizations will eventually be taken care of by the "memory_order_consume"
- * addition to forthcoming C++ standard.
- *
- * Should match rcu_assign_pointer() or rcu_xchg_pointer().
- */
-
-#define _rcu_dereference(p) ({ \
- typeof(p) _________p1 = LOAD_SHARED(p); \
- smp_read_barrier_depends(); \
- (_________p1); \
- })
-
-#define futex(...) syscall(__NR_futex, __VA_ARGS__)
-#define FUTEX_WAIT 0
-#define FUTEX_WAKE 1
+#ifdef __cplusplus
+extern "C" {
+#endif
/*
* This code section can only be included in LGPL 2.1 compatible source code.
*/
extern long urcu_gp_ctr;
-extern long __thread urcu_active_readers;
+struct urcu_reader {
+ /* Data used by both reader and synchronize_rcu() */
+ long ctr;
+ char need_mb;
+ /* Data used for registry */
+ struct list_head head __attribute__((aligned(CACHE_LINE_SIZE)));
+ pthread_t tid;
+};
+
+extern struct urcu_reader __thread urcu_reader;
extern int gp_futex;
*/
static inline void wake_up_gp(void)
{
- if (unlikely(atomic_read(&gp_futex) == -1)) {
- atomic_set(&gp_futex, 0);
- futex(&gp_futex, FUTEX_WAKE, 1,
+ if (unlikely(uatomic_read(&gp_futex) == -1)) {
+ uatomic_set(&gp_futex, 0);
+ futex_async(&gp_futex, FUTEX_WAKE, 1,
NULL, NULL, 0);
}
}
{
long tmp;
- tmp = urcu_active_readers;
+ tmp = urcu_reader.ctr;
/* urcu_gp_ctr = RCU_GP_COUNT | (~RCU_GP_CTR_BIT or RCU_GP_CTR_BIT) */
if (likely(!(tmp & RCU_GP_CTR_NEST_MASK))) {
- _STORE_SHARED(urcu_active_readers, _LOAD_SHARED(urcu_gp_ctr));
+ _STORE_SHARED(urcu_reader.ctr, _LOAD_SHARED(urcu_gp_ctr));
/*
* Set active readers count for outermost nesting level before
* accessing the pointer. See force_mb_all_threads().
*/
reader_barrier();
} else {
- _STORE_SHARED(urcu_active_readers, tmp + RCU_GP_COUNT);
+ _STORE_SHARED(urcu_reader.ctr, tmp + RCU_GP_COUNT);
}
}
{
long tmp;
- tmp = urcu_active_readers;
+ tmp = urcu_reader.ctr;
/*
* Finish using rcu before decrementing the pointer.
* See force_mb_all_threads().
*/
if (likely((tmp & RCU_GP_CTR_NEST_MASK) == RCU_GP_COUNT)) {
reader_barrier();
- _STORE_SHARED(urcu_active_readers,
- urcu_active_readers - RCU_GP_COUNT);
- /* write urcu_active_readers before read futex */
+ _STORE_SHARED(urcu_reader.ctr, urcu_reader.ctr - RCU_GP_COUNT);
+ /* write urcu_reader.ctr before read futex */
reader_barrier();
wake_up_gp();
} else {
- _STORE_SHARED(urcu_active_readers,
- urcu_active_readers - RCU_GP_COUNT);
+ _STORE_SHARED(urcu_reader.ctr, urcu_reader.ctr - RCU_GP_COUNT);
}
}
-/**
- * _rcu_assign_pointer - assign (publicize) a pointer to a new data structure
- * meant to be read by RCU read-side critical sections. Returns the assigned
- * value.
- *
- * Documents which pointers will be dereferenced by RCU read-side critical
- * sections and adds the required memory barriers on architectures requiring
- * them. It also makes sure the compiler does not reorder code initializing the
- * data structure before its publication.
- *
- * Should match rcu_dereference_pointer().
- */
-
-#define _rcu_assign_pointer(p, v) \
- ({ \
- if (!__builtin_constant_p(v) || \
- ((v) != NULL)) \
- wmb(); \
- STORE_SHARED(p, v); \
- })
-
-/**
- * _rcu_cmpxchg_pointer - same as rcu_assign_pointer, but tests if the pointer
- * is as expected by "old". If succeeds, returns the previous pointer to the
- * data structure, which can be safely freed after waiting for a quiescent state
- * using synchronize_rcu(). If fails (unexpected value), returns old (which
- * should not be freed !).
- */
-
-#define _rcu_cmpxchg_pointer(p, old, _new) \
- ({ \
- if (!__builtin_constant_p(_new) || \
- ((_new) != NULL)) \
- wmb(); \
- cmpxchg(p, old, _new); \
- })
-
-/**
- * _rcu_xchg_pointer - same as rcu_assign_pointer, but returns the previous
- * pointer to the data structure, which can be safely freed after waiting for a
- * quiescent state using synchronize_rcu().
- */
-
-#define _rcu_xchg_pointer(p, v) \
- ({ \
- if (!__builtin_constant_p(v) || \
- ((v) != NULL)) \
- wmb(); \
- xchg(p, v); \
- })
-
-/*
- * Exchanges the pointer and waits for quiescent state.
- * The pointer returned can be freed.
- */
-#define _rcu_publish_content(p, v) \
- ({ \
- void *oldptr; \
- oldptr = _rcu_xchg_pointer(p, v); \
- synchronize_rcu(); \
- oldptr; \
- })
+#ifdef __cplusplus
+}
+#endif
#endif /* _URCU_STATIC_H */
projects / urcu.git / blobdiff