X-Git-Url: http://git.liburcu.org/?p=urcu.git;a=blobdiff_plain;f=include%2Furcu%2Fstatic%2Furcu.h;h=b83e72ba6760fa1714a9f5b94da5157667bba502;hp=20fc864315e8a5a5a830a2c656401412e5f007f9;hb=4477a87021ffbfbfdb2a2084d05a084171343d36;hpb=5bbe95bb510534d0a5bab8d7d205b32d6e4a57b2 diff --git a/include/urcu/static/urcu.h b/include/urcu/static/urcu.h index 20fc864..b83e72b 100644 --- a/include/urcu/static/urcu.h +++ b/include/urcu/static/urcu.h @@ -29,252 +29,21 @@ * IBM's contributions to this file may be relicensed under LGPLv2 or later. */ -#include -#include -#include -#include - -#include -#include -#include -#include -#include -#include -#include -#include -#include - -#ifdef __cplusplus -extern "C" { -#endif - /* Default is RCU_MEMBARRIER */ #if !defined(RCU_MEMBARRIER) && !defined(RCU_MB) && !defined(RCU_SIGNAL) #define RCU_MEMBARRIER #endif -/* - * This code section can only be included in LGPL 2.1 compatible source code. - * See below for the function call wrappers which can be used in code meant to - * be only linked with the Userspace RCU library. This comes with a small - * performance degradation on the read-side due to the added function calls. - * This is required to permit relinking with newer versions of the library. - */ - -/* - * The signal number used by the RCU library can be overridden with - * -DSIGRCU= when compiling the library. - * Provide backward compatibility for liburcu 0.3.x SIGURCU. - */ -#ifdef SIGURCU -#define SIGRCU SIGURCU -#endif - -#ifndef SIGRCU -#define SIGRCU SIGUSR1 -#endif - -enum rcu_state { - RCU_READER_ACTIVE_CURRENT, - RCU_READER_ACTIVE_OLD, - RCU_READER_INACTIVE, -}; - -/* - * Slave barriers are only guaranteed to be ordered wrt master barriers. - * - * The pair ordering is detailed as (O: ordered, X: not ordered) : - * slave master - * slave X O - * master O O - */ - #ifdef RCU_MEMBARRIER -#ifdef CONFIG_RCU_FORCE_SYS_MEMBARRIER -#define rcu_has_sys_membarrier_memb 1 -#else -extern int rcu_has_sys_membarrier_memb; -#endif - -static inline void smp_mb_slave(void) -{ - if (caa_likely(rcu_has_sys_membarrier_memb)) - cmm_barrier(); - else - cmm_smp_mb(); -} +#include #endif #ifdef RCU_MB -static inline void smp_mb_slave(void) -{ - cmm_smp_mb(); -} +#include #endif #ifdef RCU_SIGNAL -static inline void smp_mb_slave(void) -{ - cmm_barrier(); -} -#endif - -/* - * The trick here is that RCU_GP_CTR_PHASE must be a multiple of 8 so we can use - * a full 8-bits, 16-bits or 32-bits bitmask for the lower order bits. - */ -#define RCU_GP_COUNT (1UL << 0) -/* Use the amount of bits equal to half of the architecture long size */ -#define RCU_GP_CTR_PHASE (1UL << (sizeof(unsigned long) << 2)) -#define RCU_GP_CTR_NEST_MASK (RCU_GP_CTR_PHASE - 1) - -struct rcu_gp { - /* - * Global grace period counter. - * Contains the current RCU_GP_CTR_PHASE. - * Also has a RCU_GP_COUNT of 1, to accelerate the reader fast path. - * Written to only by writer with mutex taken. - * Read by both writer and readers. - */ - unsigned long ctr; - - int32_t futex; -} __attribute__((aligned(CAA_CACHE_LINE_SIZE))); - -extern struct rcu_gp rcu_gp; - -struct rcu_reader { - /* Data used by both reader and synchronize_rcu() */ - unsigned long ctr; - char need_mb; - /* Data used for registry */ - struct cds_list_head node __attribute__((aligned(CAA_CACHE_LINE_SIZE))); - pthread_t tid; - /* Reader registered flag, for internal checks. */ - unsigned int registered:1; -}; - -extern DECLARE_URCU_TLS(struct rcu_reader, rcu_reader); - -/* - * Wake-up waiting synchronize_rcu(). Called from many concurrent threads. - */ -static inline void wake_up_gp(void) -{ - if (caa_unlikely(uatomic_read(&rcu_gp.futex) == -1)) { - uatomic_set(&rcu_gp.futex, 0); - /* - * Ignoring return value until we can make this function - * return something (because urcu_die() is not publicly - * exposed). - */ - (void) futex_async(&rcu_gp.futex, FUTEX_WAKE, 1, - NULL, NULL, 0); - } -} - -static inline enum rcu_state rcu_reader_state(unsigned long *ctr) -{ - unsigned long v; - - /* - * Make sure both tests below are done on the same version of *value - * to insure consistency. - */ - v = CMM_LOAD_SHARED(*ctr); - if (!(v & RCU_GP_CTR_NEST_MASK)) - return RCU_READER_INACTIVE; - if (!((v ^ rcu_gp.ctr) & RCU_GP_CTR_PHASE)) - return RCU_READER_ACTIVE_CURRENT; - return RCU_READER_ACTIVE_OLD; -} - -/* - * Helper for _rcu_read_lock(). The format of rcu_gp.ctr (as well as - * the per-thread rcu_reader.ctr) has the upper bits containing a count of - * _rcu_read_lock() nesting, and a lower-order bit that contains either zero - * or RCU_GP_CTR_PHASE. The smp_mb_slave() ensures that the accesses in - * _rcu_read_lock() happen before the subsequent read-side critical section. - */ -static inline void _rcu_read_lock_update(unsigned long tmp) -{ - if (caa_likely(!(tmp & RCU_GP_CTR_NEST_MASK))) { - _CMM_STORE_SHARED(URCU_TLS(rcu_reader).ctr, _CMM_LOAD_SHARED(rcu_gp.ctr)); - smp_mb_slave(); - } else - _CMM_STORE_SHARED(URCU_TLS(rcu_reader).ctr, tmp + RCU_GP_COUNT); -} - -/* - * Enter an RCU read-side critical section. - * - * The first cmm_barrier() call ensures that the compiler does not reorder - * the body of _rcu_read_lock() with a mutex. - * - * This function and its helper are both less than 10 lines long. The - * intent is that this function meets the 10-line criterion in LGPL, - * allowing this function to be invoked directly from non-LGPL code. - */ -static inline void _rcu_read_lock(void) -{ - unsigned long tmp; - - urcu_assert(URCU_TLS(rcu_reader).registered); - cmm_barrier(); - tmp = URCU_TLS(rcu_reader).ctr; - urcu_assert((tmp & RCU_GP_CTR_NEST_MASK) != RCU_GP_CTR_NEST_MASK); - _rcu_read_lock_update(tmp); -} - -/* - * This is a helper function for _rcu_read_unlock(). - * - * The first smp_mb_slave() call ensures that the critical section is - * seen to precede the store to rcu_reader.ctr. - * The second smp_mb_slave() call ensures that we write to rcu_reader.ctr - * before reading the update-side futex. - */ -static inline void _rcu_read_unlock_update_and_wakeup(unsigned long tmp) -{ - if (caa_likely((tmp & RCU_GP_CTR_NEST_MASK) == RCU_GP_COUNT)) { - smp_mb_slave(); - _CMM_STORE_SHARED(URCU_TLS(rcu_reader).ctr, tmp - RCU_GP_COUNT); - smp_mb_slave(); - wake_up_gp(); - } else - _CMM_STORE_SHARED(URCU_TLS(rcu_reader).ctr, tmp - RCU_GP_COUNT); -} - -/* - * Exit an RCU read-side crtical section. Both this function and its - * helper are smaller than 10 lines of code, and are intended to be - * usable by non-LGPL code, as called out in LGPL. - */ -static inline void _rcu_read_unlock(void) -{ - unsigned long tmp; - - urcu_assert(URCU_TLS(rcu_reader).registered); - tmp = URCU_TLS(rcu_reader).ctr; - urcu_assert(tmp & RCU_GP_CTR_NEST_MASK); - _rcu_read_unlock_update_and_wakeup(tmp); - cmm_barrier(); /* Ensure the compiler does not reorder us with mutex */ -} - -/* - * Returns whether within a RCU read-side critical section. - * - * This function is less than 10 lines long. The intent is that this - * function meets the 10-line criterion for LGPL, allowing this function - * to be invoked directly from non-LGPL code. - */ -static inline int _rcu_read_ongoing(void) -{ - return URCU_TLS(rcu_reader).ctr & RCU_GP_CTR_NEST_MASK; -} - -#ifdef __cplusplus -} +#include #endif #endif /* _URCU_STATIC_H */