#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.
- *
- * 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.
/*
* If a reader is really non-cooperative and refuses to commit its
- * rcu_reader_qs_gp count to memory (there is no barrier in the reader
+ * rcu_reader.ctr count to memory (there is no barrier in the reader
* per-se), kick it after a few loops waiting for it.
*/
#define KICK_READER_LOOPS 10000
}
#endif
-static inline void reader_barrier()
-{
- smp_mb();
-}
-
#define RCU_GP_ONLINE (1UL << 0)
#define RCU_GP_CTR (1UL << 1)
* Using a int rather than a char to eliminate false register dependencies
* causing stalls on some architectures.
*/
-extern unsigned long urcu_gp_ctr;
+extern unsigned long rcu_gp_ctr;
+
+struct rcu_reader {
+ /* Data used by both reader and synchronize_rcu() */
+ unsigned long ctr;
+ /* Data used for registry */
+ struct list_head node __attribute__((aligned(CACHE_LINE_SIZE)));
+ pthread_t tid;
+};
-extern unsigned long __thread rcu_reader_qs_gp;
+extern struct rcu_reader __thread rcu_reader;
extern int gp_futex;
{
if (unlikely(uatomic_read(&gp_futex) == -1)) {
uatomic_set(&gp_futex, 0);
- futex(&gp_futex, FUTEX_WAKE, 1,
+ futex_noasync(&gp_futex, FUTEX_WAKE, 1,
NULL, NULL, 0);
}
}
-#if (BITS_PER_LONG < 64)
-static inline int rcu_gp_ongoing(unsigned long *value)
-{
- unsigned long reader_gp;
-
- if (value == NULL)
- return 0;
- reader_gp = LOAD_SHARED(*value);
- return reader_gp && ((reader_gp ^ urcu_gp_ctr) & RCU_GP_CTR);
-}
-#else /* !(BITS_PER_LONG < 64) */
-static inline int rcu_gp_ongoing(unsigned long *value)
+static inline int rcu_gp_ongoing(unsigned long *ctr)
{
- unsigned long reader_gp;
+ unsigned long v;
- if (value == NULL)
- return 0;
- reader_gp = LOAD_SHARED(*value);
- return reader_gp && (reader_gp - urcu_gp_ctr > ULONG_MAX / 2);
+ v = LOAD_SHARED(*ctr);
+ return v && (v != rcu_gp_ctr);
}
-#endif /* !(BITS_PER_LONG < 64) */
static inline void _rcu_read_lock(void)
{
- rcu_assert(rcu_reader_qs_gp);
+ rcu_assert(rcu_reader.ctr);
}
static inline void _rcu_read_unlock(void)
static inline void _rcu_quiescent_state(void)
{
smp_mb();
- _STORE_SHARED(rcu_reader_qs_gp, _LOAD_SHARED(urcu_gp_ctr));
- smp_mb(); /* write rcu_reader_qs_gp before read futex */
+ _STORE_SHARED(rcu_reader.ctr, _LOAD_SHARED(rcu_gp_ctr));
+ smp_mb(); /* write rcu_reader.ctr before read futex */
wake_up_gp();
smp_mb();
}
static inline void _rcu_thread_offline(void)
{
smp_mb();
- STORE_SHARED(rcu_reader_qs_gp, 0);
- smp_mb(); /* write rcu_reader_qs_gp before read futex */
+ STORE_SHARED(rcu_reader.ctr, 0);
+ smp_mb(); /* write rcu_reader.ctr before read futex */
wake_up_gp();
}
static inline void _rcu_thread_online(void)
{
- _STORE_SHARED(rcu_reader_qs_gp, LOAD_SHARED(urcu_gp_ctr));
+ _STORE_SHARED(rcu_reader.ctr, LOAD_SHARED(rcu_gp_ctr));
smp_mb();
}
-/**
- * _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(); \
- uatomic_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(); \
- uatomic_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_QSBR_STATIC_H */