X-Git-Url: https://git.liburcu.org/?p=urcu.git;a=blobdiff_plain;f=urcu-qsbr-static.h;h=86f0fc507449451d70f276571d3c6aa1be61d98a;hp=87305cb694a9bcc4e175f37829736fcdb81d9686;hb=0ecb3fde04135d76545ce55d80abea9aef465b54;hpb=bc6c15bba37d0e6192c006c4d9815201b36d1988 diff --git a/urcu-qsbr-static.h b/urcu-qsbr-static.h index 87305cb..86f0fc5 100644 --- a/urcu-qsbr-static.h +++ b/urcu-qsbr-static.h @@ -36,62 +36,16 @@ #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. - * - * 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. @@ -103,7 +57,7 @@ /* * 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 @@ -167,11 +121,6 @@ static inline void debug_yield_init(void) } #endif -static inline void reader_barrier() -{ - smp_mb(); -} - #define RCU_GP_ONLINE (1UL << 0) #define RCU_GP_CTR (1UL << 1) @@ -180,9 +129,17 @@ static inline void reader_barrier() * 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; @@ -191,38 +148,24 @@ 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_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) @@ -232,8 +175,8 @@ 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(); } @@ -241,78 +184,19 @@ static inline void _rcu_quiescent_state(void) 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(); \ - 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_QSBR_STATIC_H */