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1 /* Copyright (C) 2005-2017 Free Software Foundation, Inc.
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2 Contributed by Richard Henderson <rth@redhat.com>.
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3
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4 This file is part of the GNU Offloading and Multi Processing Library
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5 (libgomp).
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6
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7 Libgomp is free software; you can redistribute it and/or modify it
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8 under the terms of the GNU General Public License as published by
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9 the Free Software Foundation; either version 3, or (at your option)
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10 any later version.
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11
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12 Libgomp is distributed in the hope that it will be useful, but WITHOUT ANY
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13 WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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14 FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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15 more details.
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16
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17 Under Section 7 of GPL version 3, you are granted additional
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18 permissions described in the GCC Runtime Library Exception, version
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19 3.1, as published by the Free Software Foundation.
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20
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21 You should have received a copy of the GNU General Public License and
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22 a copy of the GCC Runtime Library Exception along with this program;
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23 see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
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24 <http://www.gnu.org/licenses/>. */
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25
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26 /* This is the default POSIX 1003.1b implementation of a semaphore
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27 synchronization mechanism for libgomp. This type is private to
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28 the library.
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29
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30 This is a bit heavy weight for what we need, in that we're not
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31 interested in sem_wait as a cancelation point, but it's not too
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32 bad for a default. */
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33
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34 #include "libgomp.h"
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35
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36 #ifdef HAVE_BROKEN_POSIX_SEMAPHORES
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37 #include <stdlib.h>
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38
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39 void gomp_sem_init (gomp_sem_t *sem, int value)
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40 {
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41 int ret;
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42
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43 ret = pthread_mutex_init (&sem->mutex, NULL);
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44 if (ret)
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45 return;
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46
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47 ret = pthread_cond_init (&sem->cond, NULL);
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48 if (ret)
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49 return;
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50
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51 sem->value = value;
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52 }
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53
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54 void gomp_sem_wait (gomp_sem_t *sem)
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55 {
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56 int ret;
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57
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58 ret = pthread_mutex_lock (&sem->mutex);
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59 if (ret)
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60 return;
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61
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62 if (sem->value > 0)
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63 {
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64 sem->value--;
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65 ret = pthread_mutex_unlock (&sem->mutex);
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66 return;
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67 }
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68
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69 while (sem->value <= 0)
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70 {
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71 ret = pthread_cond_wait (&sem->cond, &sem->mutex);
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72 if (ret)
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73 {
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74 pthread_mutex_unlock (&sem->mutex);
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75 return;
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76 }
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77 }
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78
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79 sem->value--;
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80 ret = pthread_mutex_unlock (&sem->mutex);
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81 return;
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82 }
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83
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84 void gomp_sem_post (gomp_sem_t *sem)
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85 {
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86 int ret;
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87
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88 ret = pthread_mutex_lock (&sem->mutex);
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89 if (ret)
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90 return;
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91
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92 sem->value++;
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93
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94 ret = pthread_mutex_unlock (&sem->mutex);
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95 if (ret)
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96 return;
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97
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98 ret = pthread_cond_signal (&sem->cond);
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99
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100 return;
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101 }
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102
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103 void gomp_sem_destroy (gomp_sem_t *sem)
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104 {
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105 int ret;
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106
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107 ret = pthread_mutex_destroy (&sem->mutex);
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108 if (ret)
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109 return;
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110
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111 ret = pthread_cond_destroy (&sem->cond);
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112
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113 return;
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114 }
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115 #else /* HAVE_BROKEN_POSIX_SEMAPHORES */
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116 void
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117 gomp_sem_wait (gomp_sem_t *sem)
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118 {
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119 /* With POSIX, the wait can be canceled by signals. We don't want that.
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120 It is expected that the return value here is -1 and errno is EINTR. */
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121 while (sem_wait (sem) != 0)
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122 continue;
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123 }
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124 #endif
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