X-Git-Url: http://git.liburcu.org/?p=urcu.git;a=blobdiff_plain;f=urcu-qsbr.c;h=3d576b57441eac3c318f6af6fea2fab7d362ef7d;hp=788950675fe8f701de453da3de927caba2a81612;hb=02be55611d3b1c7bf4fdfcb3a9c98f621882d417;hpb=f6d18c6478b943f852d1a70fcae165fad08f019a diff --git a/urcu-qsbr.c b/urcu-qsbr.c index 7889506..3d576b5 100644 --- a/urcu-qsbr.c +++ b/urcu-qsbr.c @@ -39,20 +39,20 @@ void __attribute__((destructor)) rcu_exit(void); -static pthread_mutex_t urcu_mutex = PTHREAD_MUTEX_INITIALIZER; +static pthread_mutex_t rcu_mutex = PTHREAD_MUTEX_INITIALIZER; int gp_futex; /* * Global grace period counter. */ -unsigned long urcu_gp_ctr = RCU_GP_ONLINE; +unsigned long rcu_gp_ctr = RCU_GP_ONLINE; /* * Written to only by each individual reader. Read by both the reader and the * writers. */ -struct urcu_reader __thread urcu_reader; +struct rcu_reader __thread rcu_reader; #ifdef DEBUG_YIELD unsigned int yield_active; @@ -61,18 +61,18 @@ unsigned int __thread rand_yield; static LIST_HEAD(registry); -static void internal_urcu_lock(void) +static void internal_rcu_lock(void) { int ret; #ifndef DISTRUST_SIGNALS_EXTREME - ret = pthread_mutex_lock(&urcu_mutex); + ret = pthread_mutex_lock(&rcu_mutex); if (ret) { perror("Error in pthread mutex lock"); exit(-1); } #else /* #ifndef DISTRUST_SIGNALS_EXTREME */ - while ((ret = pthread_mutex_trylock(&urcu_mutex)) != 0) { + while ((ret = pthread_mutex_trylock(&rcu_mutex)) != 0) { if (ret != EBUSY && ret != EINTR) { printf("ret = %d, errno = %d\n", ret, errno); perror("Error in pthread mutex lock"); @@ -83,11 +83,11 @@ static void internal_urcu_lock(void) #endif /* #else #ifndef DISTRUST_SIGNALS_EXTREME */ } -static void internal_urcu_unlock(void) +static void internal_rcu_unlock(void) { int ret; - ret = pthread_mutex_unlock(&urcu_mutex); + ret = pthread_mutex_unlock(&rcu_mutex); if (ret) { perror("Error in pthread mutex unlock"); exit(-1); @@ -97,39 +97,49 @@ static void internal_urcu_unlock(void) /* * synchronize_rcu() waiting. Single thread. */ -static void wait_gp(struct urcu_reader *index) +static void wait_gp(void) { - uatomic_dec(&gp_futex); - smp_mb(); /* Write futex before read reader_gp */ - if (!rcu_gp_ongoing(&index->ctr)) { - /* Read reader_gp before write futex */ - smp_mb(); - /* Callbacks are queued, don't wait. */ - uatomic_set(&gp_futex, 0); - } else { - /* Read reader_gp before read futex */ - smp_rmb(); - if (uatomic_read(&gp_futex) == -1) - futex(&gp_futex, FUTEX_WAIT, -1, - NULL, NULL, 0); - } + /* Read reader_gp before read futex */ + smp_rmb(); + if (uatomic_read(&gp_futex) == -1) + futex_noasync(&gp_futex, FUTEX_WAIT, -1, + NULL, NULL, 0); } static void wait_for_quiescent_state(void) { - struct urcu_reader *index; + LIST_HEAD(qsreaders); + int wait_loops = 0; + struct rcu_reader *index, *tmp; if (list_empty(®istry)) return; /* * Wait for each thread rcu_reader_qs_gp count to become 0. */ - list_for_each_entry(index, ®istry, head) { - int wait_loops = 0; + for (;;) { + wait_loops++; + if (wait_loops == RCU_QS_ACTIVE_ATTEMPTS) { + uatomic_dec(&gp_futex); + /* Write futex before read reader_gp */ + smp_mb(); + } + + list_for_each_entry_safe(index, tmp, ®istry, head) { + if (!rcu_gp_ongoing(&index->ctr)) + list_move(&index->head, &qsreaders); + } - while (rcu_gp_ongoing(&index->ctr)) { - if (wait_loops++ == RCU_QS_ACTIVE_ATTEMPTS) { - wait_gp(index); + if (list_empty(®istry)) { + if (wait_loops == RCU_QS_ACTIVE_ATTEMPTS) { + /* Read reader_gp before write futex */ + smp_mb(); + uatomic_set(&gp_futex, 0); + } + break; + } else { + if (wait_loops == RCU_QS_ACTIVE_ATTEMPTS) { + wait_gp(); } else { #ifndef HAS_INCOHERENT_CACHES cpu_relax(); @@ -139,6 +149,8 @@ static void wait_for_quiescent_state(void) } } } + /* put back the reader list in the registry */ + list_splice(&qsreaders, ®istry); } /* @@ -148,18 +160,18 @@ static void wait_for_quiescent_state(void) #if (BITS_PER_LONG < 64) /* - * called with urcu_mutex held. + * called with rcu_mutex held. */ -static void switch_next_urcu_qparity(void) +static void switch_next_rcu_qparity(void) { - STORE_SHARED(urcu_gp_ctr, urcu_gp_ctr ^ RCU_GP_CTR); + STORE_SHARED(rcu_gp_ctr, rcu_gp_ctr ^ RCU_GP_CTR); } void synchronize_rcu(void) { unsigned long was_online; - was_online = urcu_reader.ctr; + was_online = rcu_reader.ctr; /* All threads should read qparity before accessing data structure * where new ptr points to. @@ -173,11 +185,11 @@ void synchronize_rcu(void) * threads registered as readers. */ if (was_online) - STORE_SHARED(urcu_reader.ctr, 0); + STORE_SHARED(rcu_reader.ctr, 0); - internal_urcu_lock(); + internal_rcu_lock(); - switch_next_urcu_qparity(); /* 0 -> 1 */ + switch_next_rcu_qparity(); /* 0 -> 1 */ /* * Must commit qparity update to memory before waiting for parity @@ -200,7 +212,7 @@ void synchronize_rcu(void) * Ensured by STORE_SHARED and LOAD_SHARED. */ - switch_next_urcu_qparity(); /* 1 -> 0 */ + switch_next_rcu_qparity(); /* 1 -> 0 */ /* * Must commit qparity update to memory before waiting for parity @@ -215,14 +227,14 @@ void synchronize_rcu(void) */ wait_for_quiescent_state(); /* Wait readers in parity 1 */ - internal_urcu_unlock(); + internal_rcu_unlock(); /* * Finish waiting for reader threads before letting the old ptr being * freed. */ if (was_online) - _STORE_SHARED(urcu_reader.ctr, LOAD_SHARED(urcu_gp_ctr)); + _STORE_SHARED(rcu_reader.ctr, LOAD_SHARED(rcu_gp_ctr)); smp_mb(); } #else /* !(BITS_PER_LONG < 64) */ @@ -230,7 +242,7 @@ void synchronize_rcu(void) { unsigned long was_online; - was_online = urcu_reader.ctr; + was_online = rcu_reader.ctr; /* * Mark the writer thread offline to make sure we don't wait for @@ -239,15 +251,15 @@ void synchronize_rcu(void) */ smp_mb(); if (was_online) - STORE_SHARED(urcu_reader.ctr, 0); + STORE_SHARED(rcu_reader.ctr, 0); - internal_urcu_lock(); - STORE_SHARED(urcu_gp_ctr, urcu_gp_ctr + RCU_GP_CTR); + internal_rcu_lock(); + STORE_SHARED(rcu_gp_ctr, rcu_gp_ctr + RCU_GP_CTR); wait_for_quiescent_state(); - internal_urcu_unlock(); + internal_rcu_unlock(); if (was_online) - _STORE_SHARED(urcu_reader.ctr, LOAD_SHARED(urcu_gp_ctr)); + _STORE_SHARED(rcu_reader.ctr, LOAD_SHARED(rcu_gp_ctr)); smp_mb(); } #endif /* !(BITS_PER_LONG < 64) */ @@ -266,38 +278,6 @@ void rcu_read_unlock(void) _rcu_read_unlock(); } -void *rcu_dereference(void *p) -{ - return _rcu_dereference(p); -} - -void *rcu_assign_pointer_sym(void **p, void *v) -{ - wmb(); - return STORE_SHARED(p, v); -} - -void *rcu_cmpxchg_pointer_sym(void **p, void *old, void *_new) -{ - wmb(); - return uatomic_cmpxchg(p, old, _new); -} - -void *rcu_xchg_pointer_sym(void **p, void *v) -{ - wmb(); - return uatomic_xchg(p, v); -} - -void *rcu_publish_content_sym(void **p, void *v) -{ - void *oldptr; - - oldptr = _rcu_xchg_pointer(p, v); - synchronize_rcu(); - return oldptr; -} - void rcu_quiescent_state(void) { _rcu_quiescent_state(); @@ -315,12 +295,12 @@ void rcu_thread_online(void) void rcu_register_thread(void) { - urcu_reader.tid = pthread_self(); - assert(urcu_reader.ctr == 0); + rcu_reader.tid = pthread_self(); + assert(rcu_reader.ctr == 0); - internal_urcu_lock(); - list_add(&urcu_reader.head, ®istry); - internal_urcu_unlock(); + internal_rcu_lock(); + list_add(&rcu_reader.head, ®istry); + internal_rcu_unlock(); _rcu_thread_online(); } @@ -331,9 +311,9 @@ void rcu_unregister_thread(void) * with a waiting writer. */ _rcu_thread_offline(); - internal_urcu_lock(); - list_del(&urcu_reader.head); - internal_urcu_unlock(); + internal_rcu_lock(); + list_del(&rcu_reader.head); + internal_rcu_unlock(); } void rcu_exit(void)