1 /* 2 * Copyright (c) 2005, David Xu <davidxu@freebsd.org> 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice unmodified, this list of conditions, and the following 10 * disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 25 * 26 * $FreeBSD$ 27 * 28 */ 29 30 #include "namespace.h" 31 #include <pthread.h> 32 #include "un-namespace.h" 33 34 #include "thr_private.h" 35 36 __weak_reference(_pthread_once, pthread_once); 37 38 #define ONCE_NEVER_DONE PTHREAD_NEEDS_INIT 39 #define ONCE_DONE PTHREAD_DONE_INIT 40 #define ONCE_IN_PROGRESS 0x02 41 #define ONCE_WAIT 0x03 42 43 /* 44 * POSIX: 45 * The pthread_once() function is not a cancellation point. However, 46 * if init_routine is a cancellation point and is canceled, the effect 47 * on once_control shall be as if pthread_once() was never called. 48 */ 49 50 static void 51 once_cancel_handler(void *arg) 52 { 53 pthread_once_t *once_control = arg; 54 55 if (atomic_cmpset_rel_int(&once_control->state, ONCE_IN_PROGRESS, ONCE_NEVER_DONE)) 56 return; 57 atomic_store_rel_int(&once_control->state, ONCE_NEVER_DONE); 58 _thr_umtx_wake(&once_control->state, INT_MAX, 0); 59 } 60 61 int 62 _pthread_once(pthread_once_t *once_control, void (*init_routine) (void)) 63 { 64 struct pthread *curthread; 65 int state; 66 67 for (;;) { 68 state = once_control->state; 69 if (state == ONCE_DONE) 70 return (0); 71 if (state == ONCE_NEVER_DONE) { 72 if (atomic_cmpset_acq_int(&once_control->state, state, ONCE_IN_PROGRESS)) 73 break; 74 } else if (state == ONCE_IN_PROGRESS) { 75 if (atomic_cmpset_acq_int(&once_control->state, state, ONCE_WAIT)) 76 _thr_umtx_wait_uint(&once_control->state, ONCE_WAIT, NULL, 0); 77 } else if (state == ONCE_WAIT) { 78 _thr_umtx_wait_uint(&once_control->state, state, NULL, 0); 79 } else 80 return (EINVAL); 81 } 82 83 curthread = _get_curthread(); 84 THR_CLEANUP_PUSH(curthread, once_cancel_handler, once_control); 85 init_routine(); 86 THR_CLEANUP_POP(curthread, 0); 87 if (atomic_cmpset_rel_int(&once_control->state, ONCE_IN_PROGRESS, ONCE_DONE)) 88 return (0); 89 atomic_store_rel_int(&once_control->state, ONCE_DONE); 90 _thr_umtx_wake(&once_control->state, INT_MAX, 0); 91 return (0); 92 } 93 94 void 95 _thr_once_init() 96 { 97 } 98