1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause 3 * 4 * Copyright (c) 2005, David Xu <davidxu@freebsd.org> 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice unmodified, this list of conditions, and the following 12 * disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 18 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 19 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 20 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 21 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 22 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 27 */ 28 29 #include <sys/cdefs.h> 30 __FBSDID("$FreeBSD$"); 31 32 #include "namespace.h" 33 #include <pthread.h> 34 #include "un-namespace.h" 35 36 #include "thr_private.h" 37 38 __weak_reference(_thr_once, pthread_once); 39 __weak_reference(_thr_once, _pthread_once); 40 41 #define ONCE_NEVER_DONE PTHREAD_NEEDS_INIT 42 #define ONCE_DONE PTHREAD_DONE_INIT 43 #define ONCE_IN_PROGRESS 0x02 44 #define ONCE_WAIT 0x03 45 46 /* 47 * POSIX: 48 * The pthread_once() function is not a cancellation point. However, 49 * if init_routine is a cancellation point and is canceled, the effect 50 * on once_control shall be as if pthread_once() was never called. 51 */ 52 53 static void 54 once_cancel_handler(void *arg) 55 { 56 pthread_once_t *once_control; 57 58 once_control = arg; 59 if (atomic_cmpset_rel_int(&once_control->state, ONCE_IN_PROGRESS, 60 ONCE_NEVER_DONE)) 61 return; 62 atomic_store_rel_int(&once_control->state, ONCE_NEVER_DONE); 63 _thr_umtx_wake(&once_control->state, INT_MAX, 0); 64 } 65 66 int 67 _thr_once(pthread_once_t *once_control, void (*init_routine)(void)) 68 { 69 struct pthread *curthread; 70 int state; 71 72 _thr_check_init(); 73 74 for (;;) { 75 state = once_control->state; 76 if (state == ONCE_DONE) { 77 atomic_thread_fence_acq(); 78 return (0); 79 } 80 if (state == ONCE_NEVER_DONE) { 81 if (atomic_cmpset_int(&once_control->state, state, 82 ONCE_IN_PROGRESS)) 83 break; 84 } else if (state == ONCE_IN_PROGRESS) { 85 if (atomic_cmpset_int(&once_control->state, state, 86 ONCE_WAIT)) 87 _thr_umtx_wait_uint(&once_control->state, 88 ONCE_WAIT, NULL, 0); 89 } else if (state == ONCE_WAIT) { 90 _thr_umtx_wait_uint(&once_control->state, state, 91 NULL, 0); 92 } else 93 return (EINVAL); 94 } 95 96 curthread = _get_curthread(); 97 THR_CLEANUP_PUSH(curthread, once_cancel_handler, once_control); 98 init_routine(); 99 THR_CLEANUP_POP(curthread, 0); 100 if (atomic_cmpset_rel_int(&once_control->state, ONCE_IN_PROGRESS, 101 ONCE_DONE)) 102 return (0); 103 atomic_store_rel_int(&once_control->state, ONCE_DONE); 104 _thr_umtx_wake(&once_control->state, INT_MAX, 0); 105 return (0); 106 } 107