1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
|
/* Linuxthreads - a simple clone()-based implementation of Posix */
/* threads for Linux. */
/* Copyright (C) 1996 Xavier Leroy (Xavier.Leroy@inria.fr) */
/* */
/* This program is free software; you can redistribute it and/or */
/* modify it under the terms of the GNU Library General Public License */
/* as published by the Free Software Foundation; either version 2 */
/* of the License, or (at your option) any later version. */
/* */
/* This program is distributed in the hope that it will be useful, */
/* but WITHOUT ANY WARRANTY; without even the implied warranty of */
/* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the */
/* GNU Library General Public License for more details. */
/* Semaphores a la POSIX 1003.1b */
#include <errno.h>
#include "pthread.h"
#include "semaphore.h"
#include "internals.h"
#include "spinlock.h"
#include "restart.h"
#include "queue.h"
int __new_sem_init(sem_t *sem, int pshared, unsigned int value)
{
if (value > SEM_VALUE_MAX) {
errno = EINVAL;
return -1;
}
if (pshared) {
errno = ENOSYS;
return -1;
}
__pthread_init_lock((struct _pthread_fastlock *) &sem->__sem_lock);
sem->__sem_value = value;
sem->__sem_waiting = NULL;
return 0;
}
int __new_sem_wait(sem_t * sem)
{
volatile pthread_descr self = thread_self();
__pthread_lock((struct _pthread_fastlock *) &sem->__sem_lock, self);
if (sem->__sem_value > 0) {
sem->__sem_value--;
__pthread_unlock((struct _pthread_fastlock *) &sem->__sem_lock);
return 0;
}
enqueue(&sem->__sem_waiting, self);
/* Wait for sem_post or cancellation */
__pthread_unlock((struct _pthread_fastlock *) &sem->__sem_lock);
suspend_with_cancellation(self);
/* This is a cancellation point */
if (THREAD_GETMEM(self, p_canceled)
&& THREAD_GETMEM(self, p_cancelstate) == PTHREAD_CANCEL_ENABLE) {
/* Remove ourselves from the waiting list if we're still on it */
__pthread_lock((struct _pthread_fastlock *) &sem->__sem_lock, self);
remove_from_queue(&sem->__sem_waiting, self);
__pthread_unlock((struct _pthread_fastlock *) &sem->__sem_lock);
pthread_exit(PTHREAD_CANCELED);
}
/* We got the semaphore */
return 0;
}
int __new_sem_trywait(sem_t * sem)
{
int retval;
__pthread_lock((struct _pthread_fastlock *) &sem->__sem_lock, NULL);
if (sem->__sem_value == 0) {
errno = EAGAIN;
retval = -1;
} else {
sem->__sem_value--;
retval = 0;
}
__pthread_unlock((struct _pthread_fastlock *) &sem->__sem_lock);
return retval;
}
int __new_sem_post(sem_t * sem)
{
pthread_descr self = thread_self();
pthread_descr th;
struct pthread_request request;
if (THREAD_GETMEM(self, p_in_sighandler) == NULL) {
__pthread_lock((struct _pthread_fastlock *) &sem->__sem_lock, self);
if (sem->__sem_waiting == NULL) {
if (sem->__sem_value >= SEM_VALUE_MAX) {
/* Overflow */
errno = ERANGE;
__pthread_unlock((struct _pthread_fastlock *) &sem->__sem_lock);
return -1;
}
sem->__sem_value++;
__pthread_unlock((struct _pthread_fastlock *) &sem->__sem_lock);
} else {
th = dequeue(&sem->__sem_waiting);
__pthread_unlock((struct _pthread_fastlock *) &sem->__sem_lock);
restart(th);
}
} else {
/* If we're in signal handler, delegate post operation to
the thread manager. */
if (__pthread_manager_request < 0) {
if (__pthread_initialize_manager() < 0) {
errno = EAGAIN;
return -1;
}
}
request.req_kind = REQ_POST;
request.req_args.post = sem;
__libc_write(__pthread_manager_request,
(char *) &request, sizeof(request));
}
return 0;
}
int __new_sem_getvalue(sem_t * sem, int * sval)
{
*sval = sem->__sem_value;
return 0;
}
int __new_sem_destroy(sem_t * sem)
{
if (sem->__sem_waiting != NULL) {
__set_errno (EBUSY);
return -1;
}
return 0;
}
sem_t *sem_open(const char *name, int oflag, ...)
{
__set_errno (ENOSYS);
return SEM_FAILED;
}
int sem_close(sem_t *sem)
{
__set_errno (ENOSYS);
return -1;
}
int sem_unlink(const char *name)
{
__set_errno (ENOSYS);
return -1;
}
#if defined PIC && DO_VERSIONING
default_symbol_version (__new_sem_init, sem_init, GLIBC_2.1);
default_symbol_version (__new_sem_wait, sem_wait, GLIBC_2.1);
default_symbol_version (__new_sem_trywait, sem_trywait, GLIBC_2.1);
default_symbol_version (__new_sem_post, sem_post, GLIBC_2.1);
default_symbol_version (__new_sem_getvalue, sem_getvalue, GLIBC_2.1);
default_symbol_version (__new_sem_destroy, sem_destroy, GLIBC_2.1);
#else
# ifdef weak_alias
weak_alias (__new_sem_init, sem_init)
weak_alias (__new_sem_wait, sem_wait)
weak_alias (__new_sem_trywait, sem_trywait)
weak_alias (__new_sem_post, sem_post)
weak_alias (__new_sem_getvalue, sem_getvalue)
weak_alias (__new_sem_destroy, sem_destroy)
# endif
#endif
|
