thr_once.c revision 220888
1112918Sjeff/* 2153496Sdavidxu * Copyright (c) 2005, David Xu <davidxu@freebsd.org> 3112918Sjeff * All rights reserved. 4112918Sjeff * 5112918Sjeff * Redistribution and use in source and binary forms, with or without 6112918Sjeff * modification, are permitted provided that the following conditions 7112918Sjeff * are met: 8112918Sjeff * 1. Redistributions of source code must retain the above copyright 9153496Sdavidxu * notice unmodified, this list of conditions, and the following 10153496Sdavidxu * disclaimer. 11112918Sjeff * 2. Redistributions in binary form must reproduce the above copyright 12112918Sjeff * notice, this list of conditions and the following disclaimer in the 13112918Sjeff * documentation and/or other materials provided with the distribution. 14112918Sjeff * 15153496Sdavidxu * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 16153496Sdavidxu * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 17153496Sdavidxu * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 18153496Sdavidxu * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 19153496Sdavidxu * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 20153496Sdavidxu * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 21153496Sdavidxu * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 22153496Sdavidxu * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 23153496Sdavidxu * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 24153496Sdavidxu * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 25112918Sjeff * 26112918Sjeff * $FreeBSD: head/lib/libthr/thread/thr_once.c 220888 2011-04-20 14:19:34Z rstone $ 27153496Sdavidxu * 28112918Sjeff */ 29144518Sdavidxu 30144518Sdavidxu#include "namespace.h" 31112918Sjeff#include <pthread.h> 32144518Sdavidxu#include "un-namespace.h" 33144518Sdavidxu 34112918Sjeff#include "thr_private.h" 35112918Sjeff 36112918Sjeff__weak_reference(_pthread_once, pthread_once); 37112918Sjeff 38144518Sdavidxu#define ONCE_NEVER_DONE PTHREAD_NEEDS_INIT 39144518Sdavidxu#define ONCE_DONE PTHREAD_DONE_INIT 40144518Sdavidxu#define ONCE_IN_PROGRESS 0x02 41179417Sdavidxu#define ONCE_WAIT 0x03 42144518Sdavidxu 43144518Sdavidxu/* 44144518Sdavidxu * POSIX: 45144518Sdavidxu * The pthread_once() function is not a cancellation point. However, 46144518Sdavidxu * if init_routine is a cancellation point and is canceled, the effect 47144518Sdavidxu * on once_control shall be as if pthread_once() was never called. 48144518Sdavidxu */ 49144518Sdavidxu 50144518Sdavidxustatic void 51144518Sdavidxuonce_cancel_handler(void *arg) 52144518Sdavidxu{ 53144518Sdavidxu pthread_once_t *once_control = arg; 54144518Sdavidxu 55179417Sdavidxu if (atomic_cmpset_rel_int(&once_control->state, ONCE_IN_PROGRESS, ONCE_NEVER_DONE)) 56179417Sdavidxu return; 57179417Sdavidxu atomic_store_rel_int(&once_control->state, ONCE_NEVER_DONE); 58179417Sdavidxu _thr_umtx_wake(&once_control->state, INT_MAX, 0); 59144518Sdavidxu} 60144518Sdavidxu 61112918Sjeffint 62144518Sdavidxu_pthread_once(pthread_once_t *once_control, void (*init_routine) (void)) 63112918Sjeff{ 64172695Sdavidxu struct pthread *curthread; 65179417Sdavidxu int state; 66144518Sdavidxu 67220888Srstone _thr_check_init(); 68220888Srstone 69179417Sdavidxu for (;;) { 70179417Sdavidxu state = once_control->state; 71179417Sdavidxu if (state == ONCE_DONE) 72179417Sdavidxu return (0); 73179417Sdavidxu if (state == ONCE_NEVER_DONE) { 74179417Sdavidxu if (atomic_cmpset_acq_int(&once_control->state, state, ONCE_IN_PROGRESS)) 75179417Sdavidxu break; 76179417Sdavidxu } else if (state == ONCE_IN_PROGRESS) { 77179417Sdavidxu if (atomic_cmpset_acq_int(&once_control->state, state, ONCE_WAIT)) 78179417Sdavidxu _thr_umtx_wait_uint(&once_control->state, ONCE_WAIT, NULL, 0); 79179417Sdavidxu } else if (state == ONCE_WAIT) { 80179417Sdavidxu _thr_umtx_wait_uint(&once_control->state, state, NULL, 0); 81179417Sdavidxu } else 82179417Sdavidxu return (EINVAL); 83179417Sdavidxu } 84179417Sdavidxu 85179417Sdavidxu curthread = _get_curthread(); 86179417Sdavidxu THR_CLEANUP_PUSH(curthread, once_cancel_handler, once_control); 87179417Sdavidxu init_routine(); 88179417Sdavidxu THR_CLEANUP_POP(curthread, 0); 89179417Sdavidxu if (atomic_cmpset_rel_int(&once_control->state, ONCE_IN_PROGRESS, ONCE_DONE)) 90144518Sdavidxu return (0); 91179417Sdavidxu atomic_store_rel_int(&once_control->state, ONCE_DONE); 92179417Sdavidxu _thr_umtx_wake(&once_control->state, INT_MAX, 0); 93112918Sjeff return (0); 94112918Sjeff} 95144518Sdavidxu 96155739Sdavidxuvoid 97155739Sdavidxu_thr_once_init() 98155739Sdavidxu{ 99155739Sdavidxu} 100