Add an internal _once() method. This works identical to pthread_once(3)
with the additional property that it is safe for routines in libc to use in both single-threaded and multi-threaded processes. Multi-threaded processes use the pthread_once() implementation from the threading library while single-threaded processes use a simplified "stub" version internal to libc. The libc stub-version of pthread_once() now also uses the simplified "stub" version as well instead of being a nop. Reviewed by: deischen, Matthew Fleming @ Isilon Suggested by: alc MFC after: 1 week
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@ -5,7 +5,8 @@
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.PATH: ${.CURDIR}/${MACHINE_ARCH}/gen ${.CURDIR}/gen
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SRCS+= __getosreldate.c __xuname.c \
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_pthread_stubs.c _rand48.c _spinlock_stub.c _thread_init.c \
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_once_stub.c _pthread_stubs.c _rand48.c _spinlock_stub.c \
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_thread_init.c \
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alarm.c arc4random.c assert.c basename.c check_utility_compat.c \
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clock.c closedir.c confstr.c \
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crypt.c ctermid.c daemon.c devname.c dirname.c disklabel.c \
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67
lib/libc/gen/_once_stub.c
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67
lib/libc/gen/_once_stub.c
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@ -0,0 +1,67 @@
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/*-
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* Copyright (c) 2009 Advanced Computing Technologies LLC
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* Written by: John H. Baldwin <jhb@FreeBSD.org>
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include "namespace.h"
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#include <pthread.h>
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#include "un-namespace.h"
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#include "libc_private.h"
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/*
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* This implements pthread_once() for the single-threaded case. It is
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* non-static so that it can be used by _pthread_stubs.c.
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*/
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int
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_libc_once(pthread_once_t *once_control, void (*init_routine)(void))
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{
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if (once_control->state == PTHREAD_DONE_INIT)
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return (0);
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init_routine();
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once_control->state = PTHREAD_DONE_INIT;
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return (0);
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}
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/*
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* This is the internal interface provided to libc. It will use
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* pthread_once() from the threading library in a multi-threaded
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* process and _libc_once() for a single-threaded library. Because
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* _libc_once() uses the same ABI for the values in the pthread_once_t
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* structure as the threading library, it is safe for a process to
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* switch from _libc_once() to pthread_once() when threading is
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* enabled.
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*/
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int
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_once(pthread_once_t *once_control, void (*init_routine)(void))
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{
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if (__isthreaded)
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return (_pthread_once(once_control, init_routine));
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return (_libc_once(once_control, init_routine));
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}
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@ -105,7 +105,7 @@ pthread_func_entry_t __thr_jtable[PJT_MAX] = {
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{PJT_DUAL_ENTRY(stub_zero)}, /* PJT_MUTEX_LOCK */
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{PJT_DUAL_ENTRY(stub_zero)}, /* PJT_MUTEX_TRYLOCK */
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{PJT_DUAL_ENTRY(stub_zero)}, /* PJT_MUTEX_UNLOCK */
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{PJT_DUAL_ENTRY(stub_zero)}, /* PJT_ONCE */
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{PJT_DUAL_ENTRY(_libc_once)}, /* PJT_ONCE */
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{PJT_DUAL_ENTRY(stub_zero)}, /* PJT_RWLOCK_DESTROY */
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{PJT_DUAL_ENTRY(stub_zero)}, /* PJT_RWLOCK_INIT */
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{PJT_DUAL_ENTRY(stub_zero)}, /* PJT_RWLOCK_RDLOCK */
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@ -34,6 +34,7 @@
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#ifndef _LIBC_PRIVATE_H_
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#define _LIBC_PRIVATE_H_
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#include <sys/_pthreadtypes.h>
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/*
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* This global flag is non-zero when a process has created one
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@ -146,6 +147,13 @@ int _yp_check(char **);
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*/
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void _init_tls(void);
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/*
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* Provides pthread_once()-like functionality for both single-threaded
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* and multi-threaded applications.
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*/
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int _once(pthread_once_t *, void (*)(void));
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int _libc_once(pthread_once_t *, void (*)(void));
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/*
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* Set the TLS thread pointer
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*/
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