X-Git-Url: https://git.liburcu.org/?p=urcu.git;a=blobdiff_plain;f=urcu-qsbr.c;h=b7c42fdb0c35deb37e8c5d76a4593746206df0d9;hp=25074d09063a60ae5c94a17b18cd9d241b1e2fb9;hb=16aa9ee87cf4364921c36025359be01390338d87;hpb=7a5a38f52b8814d0188b74a91cb635bc205df96c diff --git a/urcu-qsbr.c b/urcu-qsbr.c index 25074d0..b7c42fd 100644 --- a/urcu-qsbr.c +++ b/urcu-qsbr.c @@ -3,7 +3,7 @@ * * Userspace RCU QSBR library * - * Copyright (c) 2009 Mathieu Desnoyers + * Copyright (c) 2009 Mathieu Desnoyers * Copyright (c) 2009 Paul E. McKenney, IBM Corporation. * * This library is free software; you can redistribute it and/or @@ -59,7 +59,7 @@ unsigned int yield_active; unsigned int __thread rand_yield; #endif -static LIST_HEAD(registry); +static CDS_LIST_HEAD(registry); static void mutex_lock(pthread_mutex_t *mutex) { @@ -100,7 +100,7 @@ static void mutex_unlock(pthread_mutex_t *mutex) static void wait_gp(void) { /* Read reader_gp before read futex */ - smp_rmb(); + cmm_smp_rmb(); if (uatomic_read(&gp_futex) == -1) futex_noasync(&gp_futex, FUTEX_WAIT, -1, NULL, NULL, 0); @@ -108,24 +108,32 @@ static void wait_gp(void) static void update_counter_and_wait(void) { - LIST_HEAD(qsreaders); + CDS_LIST_HEAD(qsreaders); int wait_loops = 0; struct rcu_reader *index, *tmp; #if (BITS_PER_LONG < 64) /* Switch parity: 0 -> 1, 1 -> 0 */ - STORE_SHARED(rcu_gp_ctr, rcu_gp_ctr ^ RCU_GP_CTR); + CAA_STORE_SHARED(rcu_gp_ctr, rcu_gp_ctr ^ RCU_GP_CTR); #else /* !(BITS_PER_LONG < 64) */ /* Increment current G.P. */ - STORE_SHARED(rcu_gp_ctr, rcu_gp_ctr + RCU_GP_CTR); + CAA_STORE_SHARED(rcu_gp_ctr, rcu_gp_ctr + RCU_GP_CTR); #endif /* !(BITS_PER_LONG < 64) */ /* - * Enforce compiler-order of store to rcu_gp_ctr before before - * load rcu_reader ctr. - * This ensures synchronize_rcu() cannot be starved by readers. + * Must commit rcu_gp_ctr update to memory before waiting for quiescent + * state. Failure to do so could result in the writer waiting forever + * while new readers are always accessing data (no progress). Enforce + * compiler-order of store to rcu_gp_ctr before load rcu_reader ctr. */ - barrier(); + cmm_barrier(); + + /* + * Adding a cmm_smp_mb() which is _not_ formally required, but makes the + * model easier to understand. It does not have a big performance impact + * anyway, given this is the write-side. + */ + cmm_smp_mb(); /* * Wait for each thread rcu_reader_qs_gp count to become 0. @@ -135,18 +143,18 @@ static void update_counter_and_wait(void) if (wait_loops == RCU_QS_ACTIVE_ATTEMPTS) { uatomic_dec(&gp_futex); /* Write futex before read reader_gp */ - smp_mb(); + cmm_smp_mb(); } - list_for_each_entry_safe(index, tmp, ®istry, head) { + cds_list_for_each_entry_safe(index, tmp, ®istry, node) { if (!rcu_gp_ongoing(&index->ctr)) - list_move(&index->head, &qsreaders); + cds_list_move(&index->node, &qsreaders); } - if (list_empty(®istry)) { + if (cds_list_empty(®istry)) { if (wait_loops == RCU_QS_ACTIVE_ATTEMPTS) { /* Read reader_gp before write futex */ - smp_mb(); + cmm_smp_mb(); uatomic_set(&gp_futex, 0); } break; @@ -155,15 +163,15 @@ static void update_counter_and_wait(void) wait_gp(); } else { #ifndef HAS_INCOHERENT_CACHES - cpu_relax(); + caa_cpu_relax(); #else /* #ifndef HAS_INCOHERENT_CACHES */ - smp_mb(); + cmm_smp_mb(); #endif /* #else #ifndef HAS_INCOHERENT_CACHES */ } } } /* put back the reader list in the registry */ - list_splice(&qsreaders, ®istry); + cds_list_splice(&qsreaders, ®istry); } /* @@ -182,7 +190,7 @@ void synchronize_rcu(void) * where new ptr points to. */ /* Write new ptr before changing the qparity */ - smp_mb(); + cmm_smp_mb(); /* * Mark the writer thread offline to make sure we don't wait for @@ -190,11 +198,11 @@ void synchronize_rcu(void) * threads registered as readers. */ if (was_online) - STORE_SHARED(rcu_reader.ctr, 0); + CAA_STORE_SHARED(rcu_reader.ctr, 0); mutex_lock(&rcu_gp_lock); - if (list_empty(®istry)) + if (cds_list_empty(®istry)) goto out; /* @@ -204,18 +212,19 @@ void synchronize_rcu(void) /* * Must finish waiting for quiescent state for parity 0 before - * committing qparity update to memory. Failure to do so could result in - * the writer waiting forever while new readers are always accessing - * data (no progress). - * Ensured by STORE_SHARED and LOAD_SHARED. + * committing next rcu_gp_ctr update to memory. Failure to do so could + * result in the writer waiting forever while new readers are always + * accessing data (no progress). Enforce compiler-order of load + * rcu_reader ctr before store to rcu_gp_ctr. */ + cmm_barrier(); /* - * Adding a smp_mb() which is _not_ formally required, but makes the + * Adding a cmm_smp_mb() which is _not_ formally required, but makes the * model easier to understand. It does not have a big performance impact * anyway, given this is the write-side. */ - smp_mb(); + cmm_smp_mb(); /* * Wait for previous parity to be empty of readers. @@ -229,8 +238,8 @@ out: * freed. */ if (was_online) - _STORE_SHARED(rcu_reader.ctr, LOAD_SHARED(rcu_gp_ctr)); - smp_mb(); + _CAA_STORE_SHARED(rcu_reader.ctr, CAA_LOAD_SHARED(rcu_gp_ctr)); + cmm_smp_mb(); } #else /* !(BITS_PER_LONG < 64) */ void synchronize_rcu(void) @@ -244,20 +253,20 @@ void synchronize_rcu(void) * our own quiescent state. This allows using synchronize_rcu() in * threads registered as readers. */ - smp_mb(); + cmm_smp_mb(); if (was_online) - STORE_SHARED(rcu_reader.ctr, 0); + CAA_STORE_SHARED(rcu_reader.ctr, 0); mutex_lock(&rcu_gp_lock); - if (list_empty(®istry)) + if (cds_list_empty(®istry)) goto out; update_counter_and_wait(); out: mutex_unlock(&rcu_gp_lock); if (was_online) - _STORE_SHARED(rcu_reader.ctr, LOAD_SHARED(rcu_gp_ctr)); - smp_mb(); + _CAA_STORE_SHARED(rcu_reader.ctr, CAA_LOAD_SHARED(rcu_gp_ctr)); + cmm_smp_mb(); } #endif /* !(BITS_PER_LONG < 64) */ @@ -296,7 +305,7 @@ void rcu_register_thread(void) assert(rcu_reader.ctr == 0); mutex_lock(&rcu_gp_lock); - list_add(&rcu_reader.head, ®istry); + cds_list_add(&rcu_reader.node, ®istry); mutex_unlock(&rcu_gp_lock); _rcu_thread_online(); } @@ -309,11 +318,11 @@ void rcu_unregister_thread(void) */ _rcu_thread_offline(); mutex_lock(&rcu_gp_lock); - list_del(&rcu_reader.head); + cds_list_del(&rcu_reader.node); mutex_unlock(&rcu_gp_lock); } void rcu_exit(void) { - assert(list_empty(®istry)); + assert(cds_list_empty(®istry)); }