X-Git-Url: https://git.liburcu.org/?p=urcu.git;a=blobdiff_plain;f=urcu-static.h;h=dec8a204166d2f2c9848227a7629c53057164958;hp=3caa0f93d55058528a07c5fb20ba3a0e80191e79;hb=36bc70a84250927ba68d5096a0a9740aec157f9b;hpb=bc6c15bba37d0e6192c006c4d9815201b36d1988 diff --git a/urcu-static.h b/urcu-static.h index 3caa0f9..dec8a20 100644 --- a/urcu-static.h +++ b/urcu-static.h @@ -34,71 +34,16 @@ #include #include -#include -#include +#include +#include +#include +#include +#include +#include -/* - * 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. @@ -218,7 +163,16 @@ static inline void reader_barrier() */ 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; @@ -227,9 +181,9 @@ 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); } } @@ -253,17 +207,17 @@ static inline void _rcu_read_lock(void) { 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); } } @@ -271,85 +225,24 @@ static inline void _rcu_read_unlock(void) { 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 */