From 5bcfe82e478e2c734aef587a2030ca5cff4cd9ce Mon Sep 17 00:00:00 2001 From: John Baldwin Date: Fri, 20 Nov 2009 19:19:51 +0000 Subject: 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 --- lib/libc/gen/Makefile.inc | 3 +- lib/libc/gen/_once_stub.c | 67 +++++++++++++++++++++++++++++++++++++++++ lib/libc/gen/_pthread_stubs.c | 2 +- lib/libc/include/libc_private.h | 8 +++++ 4 files changed, 78 insertions(+), 2 deletions(-) create mode 100644 lib/libc/gen/_once_stub.c diff --git a/lib/libc/gen/Makefile.inc b/lib/libc/gen/Makefile.inc index 0bdee9ddd844c..d6b403ef375fe 100644 --- a/lib/libc/gen/Makefile.inc +++ b/lib/libc/gen/Makefile.inc @@ -5,7 +5,8 @@ .PATH: ${.CURDIR}/${MACHINE_ARCH}/gen ${.CURDIR}/gen SRCS+= __getosreldate.c __xuname.c \ - _pthread_stubs.c _rand48.c _spinlock_stub.c _thread_init.c \ + _once_stub.c _pthread_stubs.c _rand48.c _spinlock_stub.c \ + _thread_init.c \ alarm.c arc4random.c assert.c basename.c check_utility_compat.c \ clock.c closedir.c confstr.c \ crypt.c ctermid.c daemon.c devname.c dirname.c disklabel.c \ diff --git a/lib/libc/gen/_once_stub.c b/lib/libc/gen/_once_stub.c new file mode 100644 index 0000000000000..0d20c01203a6c --- /dev/null +++ b/lib/libc/gen/_once_stub.c @@ -0,0 +1,67 @@ +/*- + * Copyright (c) 2009 Advanced Computing Technologies LLC + * Written by: John H. Baldwin + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + */ + +#include +__FBSDID("$FreeBSD$"); + +#include "namespace.h" +#include +#include "un-namespace.h" +#include "libc_private.h" + +/* + * This implements pthread_once() for the single-threaded case. It is + * non-static so that it can be used by _pthread_stubs.c. + */ +int +_libc_once(pthread_once_t *once_control, void (*init_routine)(void)) +{ + + if (once_control->state == PTHREAD_DONE_INIT) + return (0); + init_routine(); + once_control->state = PTHREAD_DONE_INIT; + return (0); +} + +/* + * This is the internal interface provided to libc. It will use + * pthread_once() from the threading library in a multi-threaded + * process and _libc_once() for a single-threaded library. Because + * _libc_once() uses the same ABI for the values in the pthread_once_t + * structure as the threading library, it is safe for a process to + * switch from _libc_once() to pthread_once() when threading is + * enabled. + */ +int +_once(pthread_once_t *once_control, void (*init_routine)(void)) +{ + + if (__isthreaded) + return (_pthread_once(once_control, init_routine)); + return (_libc_once(once_control, init_routine)); +} diff --git a/lib/libc/gen/_pthread_stubs.c b/lib/libc/gen/_pthread_stubs.c index 147235e485f96..3b80e1dadd998 100644 --- a/lib/libc/gen/_pthread_stubs.c +++ b/lib/libc/gen/_pthread_stubs.c @@ -105,7 +105,7 @@ pthread_func_entry_t __thr_jtable[PJT_MAX] = { {PJT_DUAL_ENTRY(stub_zero)}, /* PJT_MUTEX_LOCK */ {PJT_DUAL_ENTRY(stub_zero)}, /* PJT_MUTEX_TRYLOCK */ {PJT_DUAL_ENTRY(stub_zero)}, /* PJT_MUTEX_UNLOCK */ - {PJT_DUAL_ENTRY(stub_zero)}, /* PJT_ONCE */ + {PJT_DUAL_ENTRY(_libc_once)}, /* PJT_ONCE */ {PJT_DUAL_ENTRY(stub_zero)}, /* PJT_RWLOCK_DESTROY */ {PJT_DUAL_ENTRY(stub_zero)}, /* PJT_RWLOCK_INIT */ {PJT_DUAL_ENTRY(stub_zero)}, /* PJT_RWLOCK_RDLOCK */ diff --git a/lib/libc/include/libc_private.h b/lib/libc/include/libc_private.h index 50903f3c74fae..bcf2b1cadd434 100644 --- a/lib/libc/include/libc_private.h +++ b/lib/libc/include/libc_private.h @@ -34,6 +34,7 @@ #ifndef _LIBC_PRIVATE_H_ #define _LIBC_PRIVATE_H_ +#include /* * This global flag is non-zero when a process has created one @@ -146,6 +147,13 @@ int _yp_check(char **); */ void _init_tls(void); +/* + * Provides pthread_once()-like functionality for both single-threaded + * and multi-threaded applications. + */ +int _once(pthread_once_t *, void (*)(void)); +int _libc_once(pthread_once_t *, void (*)(void)); + /* * Set the TLS thread pointer */ -- cgit v1.3