1 /* Copyright (C) 2005, 2006, 2009 Free Software Foundation, Inc. 2 Contributed by Richard Henderson <rth@redhat.com>. 3 4 This file is part of the GNU OpenMP Library (libgomp). 5 6 Libgomp is free software; you can redistribute it and/or modify it 7 under the terms of the GNU General Public License as published by 8 the Free Software Foundation; either version 3, or (at your option) 9 any later version. 10 11 Libgomp is distributed in the hope that it will be useful, but WITHOUT ANY 12 WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS 13 FOR A PARTICULAR PURPOSE. See the GNU General Public License for 14 more details. 15 16 Under Section 7 of GPL version 3, you are granted additional 17 permissions described in the GCC Runtime Library Exception, version 18 3.1, as published by the Free Software Foundation. 19 20 You should have received a copy of the GNU General Public License and 21 a copy of the GCC Runtime Library Exception along with this program; 22 see the files COPYING3 and COPYING.RUNTIME respectively. If not, see 23 <http://www.gnu.org/licenses/>. */ 24 25 /* This is the default POSIX 1003.1b implementation of a semaphore 26 synchronization mechanism for libgomp. This type is private to 27 the library. 28 29 This is a bit heavy weight for what we need, in that we're not 30 interested in sem_wait as a cancelation point, but it's not too 31 bad for a default. */ 32 33 #include "libgomp.h" 34 35 #ifdef HAVE_BROKEN_POSIX_SEMAPHORES 36 #include <stdlib.h> 37 38 void gomp_sem_init (gomp_sem_t *sem, int value) 39 { 40 int ret; 41 42 ret = pthread_mutex_init (&sem->mutex, NULL); 43 if (ret) 44 return; 45 46 ret = pthread_cond_init (&sem->cond, NULL); 47 if (ret) 48 return; 49 50 sem->value = value; 51 } 52 53 void gomp_sem_wait (gomp_sem_t *sem) 54 { 55 int ret; 56 57 ret = pthread_mutex_lock (&sem->mutex); 58 if (ret) 59 return; 60 61 if (sem->value > 0) 62 { 63 sem->value--; 64 ret = pthread_mutex_unlock (&sem->mutex); 65 return; 66 } 67 68 while (sem->value <= 0) 69 { 70 ret = pthread_cond_wait (&sem->cond, &sem->mutex); 71 if (ret) 72 { 73 pthread_mutex_unlock (&sem->mutex); 74 return; 75 } 76 } 77 78 sem->value--; 79 ret = pthread_mutex_unlock (&sem->mutex); 80 return; 81 } 82 83 void gomp_sem_post (gomp_sem_t *sem) 84 { 85 int ret; 86 87 ret = pthread_mutex_lock (&sem->mutex); 88 if (ret) 89 return; 90 91 sem->value++; 92 93 ret = pthread_mutex_unlock (&sem->mutex); 94 if (ret) 95 return; 96 97 ret = pthread_cond_signal (&sem->cond); 98 99 return; 100 } 101 102 void gomp_sem_destroy (gomp_sem_t *sem) 103 { 104 int ret; 105 106 ret = pthread_mutex_destroy (&sem->mutex); 107 if (ret) 108 return; 109 110 ret = pthread_cond_destroy (&sem->cond); 111 112 return; 113 } 114 #else /* HAVE_BROKEN_POSIX_SEMAPHORES */ 115 void 116 gomp_sem_wait (gomp_sem_t *sem) 117 { 118 /* With POSIX, the wait can be canceled by signals. We don't want that. 119 It is expected that the return value here is -1 and errno is EINTR. */ 120 while (sem_wait (sem) != 0) 121 continue; 122 } 123 #endif 124