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