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 #include "namespace.h" 31 #include <pthread.h> 32 #include "un-namespace.h" 33 34 #include "thr_private.h" 35 36 __weak_reference(_thr_once, pthread_once); 37 __weak_reference(_thr_once, _pthread_once); 38 39 #define ONCE_NEVER_DONE PTHREAD_NEEDS_INIT 40 #define ONCE_DONE PTHREAD_DONE_INIT 41 #define ONCE_IN_PROGRESS 0x02 42 #define ONCE_WAIT 0x03 43 44 /* 45 * POSIX: 46 * The pthread_once() function is not a cancellation point. However, 47 * if init_routine is a cancellation point and is canceled, the effect 48 * on once_control shall be as if pthread_once() was never called. 49 */ 50 51 static void 52 once_cancel_handler(void *arg) 53 { 54 pthread_once_t *once_control; 55 56 once_control = arg; 57 if (atomic_cmpset_rel_int(&once_control->state, ONCE_IN_PROGRESS, 58 ONCE_NEVER_DONE)) 59 return; 60 atomic_store_rel_int(&once_control->state, ONCE_NEVER_DONE); 61 _thr_umtx_wake(&once_control->state, INT_MAX, 0); 62 } 63 64 int 65 _thr_once(pthread_once_t *once_control, void (*init_routine)(void)) 66 { 67 struct pthread *curthread; 68 int state; 69 70 _thr_check_init(); 71 72 for (;;) { 73 state = once_control->state; 74 if (state == ONCE_DONE) { 75 atomic_thread_fence_acq(); 76 return (0); 77 } 78 if (state == ONCE_NEVER_DONE) { 79 if (atomic_cmpset_int(&once_control->state, state, 80 ONCE_IN_PROGRESS)) 81 break; 82 } else if (state == ONCE_IN_PROGRESS) { 83 if (atomic_cmpset_int(&once_control->state, state, 84 ONCE_WAIT)) 85 _thr_umtx_wait_uint(&once_control->state, 86 ONCE_WAIT, NULL, 0); 87 } else if (state == ONCE_WAIT) { 88 _thr_umtx_wait_uint(&once_control->state, state, 89 NULL, 0); 90 } else 91 return (EINVAL); 92 } 93 94 curthread = _get_curthread(); 95 THR_CLEANUP_PUSH(curthread, once_cancel_handler, once_control); 96 init_routine(); 97 THR_CLEANUP_POP(curthread, 0); 98 if (atomic_cmpset_rel_int(&once_control->state, ONCE_IN_PROGRESS, 99 ONCE_DONE)) 100 return (0); 101 atomic_store_rel_int(&once_control->state, ONCE_DONE); 102 _thr_umtx_wake(&once_control->state, INT_MAX, 0); 103 return (0); 104 } 105