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 "namespace.h" 30 #include <pthread.h> 31 #include "un-namespace.h" 32 33 #include "thr_private.h" 34 35 __weak_reference(_thr_once, pthread_once); 36 __weak_reference(_thr_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; 54 55 once_control = arg; 56 if (atomic_cmpset_rel_int(&once_control->state, ONCE_IN_PROGRESS, 57 ONCE_NEVER_DONE)) 58 return; 59 atomic_store_rel_int(&once_control->state, ONCE_NEVER_DONE); 60 _thr_umtx_wake(&once_control->state, INT_MAX, 0); 61 } 62 63 int 64 _thr_once(pthread_once_t *once_control, void (*init_routine)(void)) 65 { 66 struct pthread *curthread; 67 int state; 68 69 _thr_check_init(); 70 71 for (;;) { 72 state = once_control->state; 73 if (state == ONCE_DONE) { 74 atomic_thread_fence_acq(); 75 return (0); 76 } 77 if (state == ONCE_NEVER_DONE) { 78 if (atomic_cmpset_int(&once_control->state, state, 79 ONCE_IN_PROGRESS)) 80 break; 81 } else if (state == ONCE_IN_PROGRESS) { 82 if (atomic_cmpset_int(&once_control->state, state, 83 ONCE_WAIT)) 84 _thr_umtx_wait_uint(&once_control->state, 85 ONCE_WAIT, NULL, 0); 86 } else if (state == ONCE_WAIT) { 87 _thr_umtx_wait_uint(&once_control->state, state, 88 NULL, 0); 89 } else 90 return (EINVAL); 91 } 92 93 curthread = _get_curthread(); 94 THR_CLEANUP_PUSH(curthread, once_cancel_handler, once_control); 95 init_routine(); 96 THR_CLEANUP_POP(curthread, 0); 97 if (atomic_cmpset_rel_int(&once_control->state, ONCE_IN_PROGRESS, 98 ONCE_DONE)) 99 return (0); 100 atomic_store_rel_int(&once_control->state, ONCE_DONE); 101 _thr_umtx_wake(&once_control->state, INT_MAX, 0); 102 return (0); 103 } 104