X-Git-Url: https://git.liburcu.org/?p=urcu.git;a=blobdiff_plain;f=urcu-qsbr-static.h;h=72d35957e802c42733ed415d871a9c4aa54a74ac;hp=22a93b2fd7a823d21c76cbbd1ad5c6bf3b0495e4;hb=36bc70a84250927ba68d5096a0a9740aec157f9b;hpb=47d2f29ead2c92123069ebf7b84c6e48cf91612a diff --git a/urcu-qsbr-static.h b/urcu-qsbr-static.h index 22a93b2..72d3595 100644 --- a/urcu-qsbr-static.h +++ b/urcu-qsbr-static.h @@ -33,59 +33,19 @@ #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. - * - * Should match rcu_assign_pointer() or rcu_xchg_pointer(). - */ +#include +#include +#include +#include +#include +#include -#define _rcu_dereference(p) ({ \ - typeof(p) _________p1 = LOAD_SHARED(p); \ - smp_read_barrier_depends(); \ - (_________p1); \ - }) +#ifdef __cplusplus +extern "C" { +#endif /* * This code section can only be included in LGPL 2.1 compatible source code. @@ -97,11 +57,16 @@ /* * 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 + * urcu_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 +/* + * Active attempts to check for reader Q.S. before calling futex(). + */ +#define RCU_QS_ACTIVE_ATTEMPTS 100 + #ifdef DEBUG_RCU #define rcu_assert(args...) assert(args) #else @@ -171,7 +136,29 @@ static inline void reader_barrier() */ extern unsigned long urcu_gp_ctr; -extern unsigned long __thread rcu_reader_qs_gp; +struct urcu_reader { + /* Data used by both reader and synchronize_rcu() */ + unsigned long ctr; + /* 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; + +/* + * Wake-up waiting synchronize_rcu(). Called from many concurrent threads. + */ +static inline void wake_up_gp(void) +{ + if (unlikely(uatomic_read(&gp_futex) == -1)) { + uatomic_set(&gp_futex, 0); + futex_noasync(&gp_futex, FUTEX_WAKE, 1, + NULL, NULL, 0); + } +} #if (BITS_PER_LONG < 64) static inline int rcu_gp_ongoing(unsigned long *value) @@ -197,7 +184,7 @@ static inline int rcu_gp_ongoing(unsigned long *value) static inline void _rcu_read_lock(void) { - rcu_assert(rcu_reader_qs_gp); + rcu_assert(urcu_reader.ctr); } static inline void _rcu_read_unlock(void) @@ -207,67 +194,28 @@ 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)); + _STORE_SHARED(urcu_reader.ctr, _LOAD_SHARED(urcu_gp_ctr)); + smp_mb(); /* write urcu_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); + STORE_SHARED(urcu_reader.ctr, 0); + smp_mb(); /* write urcu_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(urcu_reader.ctr, LOAD_SHARED(urcu_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_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_QSBR_STATIC_H */