X-Git-Url: https://git.lttng.org/?a=blobdiff_plain;f=src%2Furcu.c;h=ccc134ca9d8c79363523c9b2b9670cd919ab5784;hb=542fb0dc9860863b1a869f9ad526da699b2179ff;hp=e64432f8bb7034cf3ef63cacc03aca7884133b74;hpb=70469b43316ecc8d6053550504858ad8a8ef9b16;p=userspace-rcu.git diff --git a/src/urcu.c b/src/urcu.c index e64432f..ccc134c 100644 --- a/src/urcu.c +++ b/src/urcu.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.c - * * Userspace RCU 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. */ @@ -30,7 +16,6 @@ #include #include #include -#include #include #include #include @@ -39,6 +24,7 @@ #include #include +#include #include #include #include @@ -94,8 +80,6 @@ static int urcu_memb_has_sys_membarrier_private_expedited; * uninitialized variable. */ int urcu_memb_has_sys_membarrier = 0; -URCU_ATTR_ALIAS("urcu_memb_has_sys_membarrier") -extern int rcu_has_sys_membarrier_memb; #endif void __attribute__((constructor)) rcu_init(void); @@ -105,17 +89,19 @@ void __attribute__((constructor)) rcu_init(void); void rcu_init(void) { } -URCU_ATTR_ALIAS(urcu_stringify(rcu_init)) -void alias_rcu_init(void); #endif #ifdef RCU_SIGNAL static int init_done; void __attribute__((constructor)) rcu_init(void); -void __attribute__((destructor)) rcu_exit(void); + +static DEFINE_URCU_TLS(int, rcu_signal_was_blocked); #endif +void __attribute__((destructor)) rcu_exit(void); +static void urcu_call_rcu_exit(void); + /* * rcu_gp_lock ensures mutual exclusion between threads calling * synchronize_rcu(). @@ -132,15 +118,12 @@ static pthread_mutex_t rcu_gp_lock = PTHREAD_MUTEX_INITIALIZER; */ static pthread_mutex_t rcu_registry_lock = PTHREAD_MUTEX_INITIALIZER; struct urcu_gp rcu_gp = { .ctr = URCU_GP_COUNT }; -URCU_ATTR_ALIAS(urcu_stringify(rcu_gp)) -extern struct urcu_gp alias_rcu_gp; /* * Written to only by each individual reader. Read by both the reader and the * writers. */ DEFINE_URCU_TLS(struct urcu_reader, rcu_reader); -DEFINE_URCU_TLS_ALIAS(struct urcu_reader, rcu_reader, alias_rcu_reader); static CDS_LIST_HEAD(registry); @@ -266,17 +249,25 @@ static void wait_gp(void) smp_mb_master(); /* Temporarily unlock the registry lock. */ mutex_unlock(&rcu_registry_lock); - if (uatomic_read(&rcu_gp.futex) != -1) - goto end; - while (futex_async(&rcu_gp.futex, FUTEX_WAIT, -1, - NULL, NULL, 0)) { + while (uatomic_read(&rcu_gp.futex) == -1) { + if (!futex_async(&rcu_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. */ goto end; 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); @@ -448,7 +439,7 @@ void synchronize_rcu(void) /* * Wait for readers to observe original parity or be quiescent. * wait_for_readers() can release and grab again rcu_registry_lock - * interally. + * internally. */ wait_for_readers(®istry, &cur_snap_readers, &qsreaders); @@ -490,7 +481,7 @@ void synchronize_rcu(void) /* * Wait for readers to observe new parity or be quiescent. * wait_for_readers() can release and grab again rcu_registry_lock - * interally. + * internally. */ wait_for_readers(&cur_snap_readers, NULL, &qsreaders); @@ -516,8 +507,6 @@ out: */ urcu_wake_all_waiters(&waiters); } -URCU_ATTR_ALIAS(urcu_stringify(synchronize_rcu)) -void alias_synchronize_rcu(); /* * library wrappers to be used by non-LGPL compatible source code. @@ -527,49 +516,85 @@ void rcu_read_lock(void) { _rcu_read_lock(); } -URCU_ATTR_ALIAS(urcu_stringify(rcu_read_lock)) -void alias_rcu_read_lock(); void rcu_read_unlock(void) { _rcu_read_unlock(); } -URCU_ATTR_ALIAS(urcu_stringify(rcu_read_unlock)) -void alias_rcu_read_unlock(); int rcu_read_ongoing(void) { return _rcu_read_ongoing(); } -URCU_ATTR_ALIAS(urcu_stringify(rcu_read_ongoing)) -void alias_rcu_read_ongoing(); + +#ifdef RCU_SIGNAL +/* + * Make sure the signal used by the urcu-signal flavor is unblocked + * while the thread is registered. + */ +static +void urcu_signal_unblock(void) +{ + sigset_t mask, oldmask; + int ret; + + ret = sigemptyset(&mask); + urcu_posix_assert(!ret); + ret = sigaddset(&mask, SIGRCU); + urcu_posix_assert(!ret); + ret = pthread_sigmask(SIG_UNBLOCK, &mask, &oldmask); + urcu_posix_assert(!ret); + URCU_TLS(rcu_signal_was_blocked) = sigismember(&oldmask, SIGRCU); +} + +static +void urcu_signal_restore(void) +{ + sigset_t mask; + int ret; + + if (!URCU_TLS(rcu_signal_was_blocked)) + return; + ret = sigemptyset(&mask); + urcu_posix_assert(!ret); + ret = sigaddset(&mask, SIGRCU); + urcu_posix_assert(!ret); + ret = pthread_sigmask(SIG_BLOCK, &mask, NULL); + urcu_posix_assert(!ret); +} +#else +static +void urcu_signal_unblock(void) { } +static +void urcu_signal_restore(void) { } +#endif void rcu_register_thread(void) { + urcu_signal_unblock(); + URCU_TLS(rcu_reader).tid = pthread_self(); - assert(URCU_TLS(rcu_reader).need_mb == 0); - assert(!(URCU_TLS(rcu_reader).ctr & URCU_GP_CTR_NEST_MASK)); + urcu_posix_assert(URCU_TLS(rcu_reader).need_mb == 0); + urcu_posix_assert(!(URCU_TLS(rcu_reader).ctr & URCU_GP_CTR_NEST_MASK)); mutex_lock(&rcu_registry_lock); - assert(!URCU_TLS(rcu_reader).registered); + urcu_posix_assert(!URCU_TLS(rcu_reader).registered); URCU_TLS(rcu_reader).registered = 1; rcu_init(); /* In case gcc does not support constructor attribute */ cds_list_add(&URCU_TLS(rcu_reader).node, ®istry); mutex_unlock(&rcu_registry_lock); } -URCU_ATTR_ALIAS(urcu_stringify(rcu_register_thread)) -void alias_rcu_register_thread(); void rcu_unregister_thread(void) { mutex_lock(&rcu_registry_lock); - assert(URCU_TLS(rcu_reader).registered); + urcu_posix_assert(URCU_TLS(rcu_reader).registered); URCU_TLS(rcu_reader).registered = 0; cds_list_del(&URCU_TLS(rcu_reader).node); mutex_unlock(&rcu_registry_lock); + + urcu_signal_restore(); } -URCU_ATTR_ALIAS(urcu_stringify(rcu_unregister_thread)) -void alias_rcu_unregister_thread(); #ifdef RCU_MEMBARRIER @@ -617,8 +642,6 @@ void rcu_init(void) init_done = 1; rcu_sys_membarrier_init(); } -URCU_ATTR_ALIAS(urcu_stringify(rcu_init)) -void alias_rcu_init(void); #endif #ifdef RCU_SIGNAL @@ -660,27 +683,25 @@ void rcu_init(void) if (ret) urcu_die(errno); } -URCU_ATTR_ALIAS(urcu_stringify(rcu_init)) -void alias_rcu_init(void); + +/* + * Don't unregister the SIGRCU signal handler anymore, because + * call_rcu threads could still be using it shortly before the + * application exits. + * Assertion disabled because call_rcu threads are now rcu + * readers, and left running at exit. + * urcu_posix_assert(cds_list_empty(®istry)); + */ + +#endif /* #ifdef RCU_SIGNAL */ void rcu_exit(void) { - /* - * Don't unregister the SIGRCU signal handler anymore, because - * call_rcu threads could still be using it shortly before the - * application exits. - * Assertion disabled because call_rcu threads are now rcu - * readers, and left running at exit. - * assert(cds_list_empty(®istry)); - */ + urcu_call_rcu_exit(); } -URCU_ATTR_ALIAS(urcu_stringify(rcu_exit)) -void alias_rcu_exit(void); - -#endif /* #ifdef RCU_SIGNAL */ DEFINE_RCU_FLAVOR(rcu_flavor); -DEFINE_RCU_FLAVOR_ALIAS(rcu_flavor, alias_rcu_flavor); #include "urcu-call-rcu-impl.h" #include "urcu-defer-impl.h" +#include "urcu-poll-impl.h"