X-Git-Url: https://git.lttng.org/?p=urcu.git;a=blobdiff_plain;f=src%2Furcu-qsbr.c;h=40c0fbdb35519983186c67615f8c285a691f91d8;hp=e934d3b57f7681225e1577089fdd589b17a6ad33;hb=HEAD;hpb=f99c6e92aaa1582e6cd19d93d44d91d968f39aa7 diff --git a/src/urcu-qsbr.c b/src/urcu-qsbr.c index e934d3b..e7ee180 100644 --- a/src/urcu-qsbr.c +++ b/src/urcu-qsbr.c @@ -1,25 +1,11 @@ +// SPDX-FileCopyrightText: 2009 Mathieu Desnoyers +// SPDX-FileCopyrightText: 2009 Paul E. McKenney, IBM Corporation. +// +// SPDX-License-Identifier: LGPL-2.1-or-later + /* - * urcu-qsbr.c - * * Userspace RCU QSBR library * - * Copyright (c) 2009 Mathieu Desnoyers - * Copyright (c) 2009 Paul E. McKenney, IBM Corporation. - * - * This library is free software; you can redistribute it and/or - * modify it under the terms of the GNU Lesser General Public - * License as published by the Free Software Foundation; either - * version 2.1 of the License, or (at your option) any later version. - * - * This library is distributed in the hope that it will be useful, - * but WITHOUT ANY WARRANTY; without even the implied warranty of - * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU - * Lesser General Public License for more details. - * - * You should have received a copy of the GNU Lesser General Public - * License along with this library; if not, write to the Free Software - * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA - * * IBM's contributions to this file may be relicensed under LGPLv2 or later. */ @@ -28,13 +14,14 @@ #include #include #include -#include #include #include #include #include #include +#include +#include #include #include #define BUILD_QSBR_LIB @@ -53,6 +40,7 @@ #define _LGPL_SOURCE void __attribute__((destructor)) urcu_qsbr_exit(void); +static void urcu_call_rcu_exit(void); /* * rcu_gp_lock ensures mutual exclusion between threads calling @@ -123,17 +111,25 @@ static void wait_gp(void) { /* Read reader_gp before read futex */ cmm_smp_rmb(); - if (uatomic_read(&urcu_qsbr_gp.futex) != -1) - return; - while (futex_noasync(&urcu_qsbr_gp.futex, FUTEX_WAIT, -1, - NULL, NULL, 0)) { + while (uatomic_read(&urcu_qsbr_gp.futex) == -1) { + if (!futex_noasync(&urcu_qsbr_gp.futex, FUTEX_WAIT, -1, NULL, NULL, 0)) { + /* + * Prior queued wakeups queued by unrelated code + * using the same address can cause futex wait to + * return 0 even through the futex value is still + * -1 (spurious wakeups). Check the value again + * in user-space to validate whether it really + * differs from -1. + */ + continue; + } switch (errno) { - case EWOULDBLOCK: + case EAGAIN: /* Value already changed. */ return; case EINTR: /* Retry if interrupted by signal. */ - break; /* Get out of switch. */ + break; /* Get out of switch. Check again. */ default: /* Unexpected error. */ urcu_die(errno); @@ -147,7 +143,8 @@ static void wait_gp(void) */ static void wait_for_readers(struct cds_list_head *input_readers, struct cds_list_head *cur_snap_readers, - struct cds_list_head *qsreaders) + struct cds_list_head *qsreaders, + cmm_annotate_t *group) { unsigned int wait_loops = 0; struct urcu_qsbr_reader *index, *tmp; @@ -174,7 +171,7 @@ static void wait_for_readers(struct cds_list_head *input_readers, cmm_smp_mb(); } cds_list_for_each_entry_safe(index, tmp, input_readers, node) { - switch (urcu_qsbr_reader_state(&index->ctr)) { + switch (urcu_qsbr_reader_state(&index->ctr, group)) { case URCU_READER_ACTIVE_CURRENT: if (cur_snap_readers) { cds_list_move(&index->node, @@ -199,8 +196,7 @@ static void wait_for_readers(struct cds_list_head *input_readers, if (cds_list_empty(input_readers)) { if (wait_loops >= RCU_QS_ACTIVE_ATTEMPTS) { /* Read reader_gp before write futex */ - cmm_smp_mb(); - uatomic_set(&urcu_qsbr_gp.futex, 0); + uatomic_store(&urcu_qsbr_gp.futex, 0, CMM_RELEASE); } break; } else { @@ -229,6 +225,8 @@ static void wait_for_readers(struct cds_list_head *input_readers, #if (CAA_BITS_PER_LONG < 64) void urcu_qsbr_synchronize_rcu(void) { + cmm_annotate_define(acquire_group); + cmm_annotate_define(release_group); CDS_LIST_HEAD(cur_snap_readers); CDS_LIST_HEAD(qsreaders); unsigned long was_online; @@ -249,6 +247,7 @@ void urcu_qsbr_synchronize_rcu(void) urcu_qsbr_thread_offline(); else cmm_smp_mb(); + cmm_annotate_group_mb_release(&release_group); /* * Add ourself to gp_waiters queue of threads awaiting to wait @@ -280,7 +279,7 @@ void urcu_qsbr_synchronize_rcu(void) * wait_for_readers() can release and grab again rcu_registry_lock * internally. */ - wait_for_readers(®istry, &cur_snap_readers, &qsreaders); + wait_for_readers(®istry, &cur_snap_readers, &qsreaders, &acquire_group); /* * Must finish waiting for quiescent state for original parity @@ -300,7 +299,8 @@ void urcu_qsbr_synchronize_rcu(void) cmm_smp_mb(); /* Switch parity: 0 -> 1, 1 -> 0 */ - CMM_STORE_SHARED(urcu_qsbr_gp.ctr, urcu_qsbr_gp.ctr ^ URCU_QSBR_GP_CTR); + cmm_annotate_group_mem_release(&release_group, &urcu_qsbr_gp.ctr); + uatomic_store(&urcu_qsbr_gp.ctr, urcu_qsbr_gp.ctr ^ URCU_QSBR_GP_CTR, CMM_RELAXED); /* * Must commit urcu_qsbr_gp.ctr update to memory before waiting for @@ -323,7 +323,7 @@ void urcu_qsbr_synchronize_rcu(void) * wait_for_readers() can release and grab again rcu_registry_lock * internally. */ - wait_for_readers(&cur_snap_readers, NULL, &qsreaders); + wait_for_readers(&cur_snap_readers, NULL, &qsreaders, &acquire_group); /* * Put quiescent reader list back into registry. @@ -338,6 +338,8 @@ gp_end: * Finish waiting for reader threads before letting the old ptr being * freed. */ + cmm_annotate_group_mb_acquire(&acquire_group); + if (was_online) urcu_qsbr_thread_online(); else @@ -346,6 +348,8 @@ gp_end: #else /* !(CAA_BITS_PER_LONG < 64) */ void urcu_qsbr_synchronize_rcu(void) { + cmm_annotate_define(acquire_group); + cmm_annotate_define(release_group); CDS_LIST_HEAD(qsreaders); unsigned long was_online; DEFINE_URCU_WAIT_NODE(wait, URCU_WAIT_WAITING); @@ -362,6 +366,7 @@ void urcu_qsbr_synchronize_rcu(void) urcu_qsbr_thread_offline(); else cmm_smp_mb(); + cmm_annotate_group_mb_release(&release_group); /* * Add ourself to gp_waiters queue of threads awaiting to wait @@ -389,7 +394,8 @@ void urcu_qsbr_synchronize_rcu(void) goto out; /* Increment current G.P. */ - CMM_STORE_SHARED(urcu_qsbr_gp.ctr, urcu_qsbr_gp.ctr + URCU_QSBR_GP_CTR); + cmm_annotate_group_mem_release(&release_group, &urcu_qsbr_gp.ctr); + uatomic_store(&urcu_qsbr_gp.ctr, urcu_qsbr_gp.ctr + URCU_QSBR_GP_CTR, CMM_RELAXED); /* * Must commit urcu_qsbr_gp.ctr update to memory before waiting for @@ -412,7 +418,7 @@ void urcu_qsbr_synchronize_rcu(void) * wait_for_readers() can release and grab again rcu_registry_lock * internally. */ - wait_for_readers(®istry, NULL, &qsreaders); + wait_for_readers(®istry, NULL, &qsreaders, &acquire_group); /* * Put quiescent reader list back into registry. @@ -427,6 +433,8 @@ gp_end: urcu_qsbr_thread_online(); else cmm_smp_mb(); + + cmm_annotate_group_mb_acquire(&acquire_group); } #endif /* !(CAA_BITS_PER_LONG < 64) */ @@ -470,10 +478,10 @@ void urcu_qsbr_thread_online(void) void urcu_qsbr_register_thread(void) { URCU_TLS(urcu_qsbr_reader).tid = pthread_self(); - assert(URCU_TLS(urcu_qsbr_reader).ctr == 0); + urcu_posix_assert(URCU_TLS(urcu_qsbr_reader).ctr == 0); mutex_lock(&rcu_registry_lock); - assert(!URCU_TLS(urcu_qsbr_reader).registered); + urcu_posix_assert(!URCU_TLS(urcu_qsbr_reader).registered); URCU_TLS(urcu_qsbr_reader).registered = 1; cds_list_add(&URCU_TLS(urcu_qsbr_reader).node, ®istry); mutex_unlock(&rcu_registry_lock); @@ -487,7 +495,7 @@ void urcu_qsbr_unregister_thread(void) * with a waiting writer. */ _urcu_qsbr_thread_offline(); - assert(URCU_TLS(urcu_qsbr_reader).registered); + urcu_posix_assert(URCU_TLS(urcu_qsbr_reader).registered); URCU_TLS(urcu_qsbr_reader).registered = 0; mutex_lock(&rcu_registry_lock); cds_list_del(&URCU_TLS(urcu_qsbr_reader).node); @@ -499,11 +507,13 @@ void urcu_qsbr_exit(void) /* * Assertion disabled because call_rcu threads are now rcu * readers, and left running at exit. - * assert(cds_list_empty(®istry)); + * urcu_posix_assert(cds_list_empty(®istry)); */ + urcu_call_rcu_exit(); } DEFINE_RCU_FLAVOR(rcu_flavor); #include "urcu-call-rcu-impl.h" #include "urcu-defer-impl.h" +#include "urcu-poll-impl.h"