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
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
|
/*
* Copyright (c) 1995 John Birrell <jb@cimlogic.com.au>.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by John Birrell.
* 4. Neither the name of the author nor the names of any co-contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
*/
#include <stdlib.h>
#include <errno.h>
#ifdef _THREAD_SAFE
#include <pthread.h>
#include "pthread_private.h"
int
pthread_mutex_init(pthread_mutex_t * mutex,
const pthread_mutexattr_t * mutex_attr)
{
enum pthread_mutextype type;
pthread_mutex_t pmutex;
int ret = 0;
int status;
if (mutex == NULL) {
ret = EINVAL;
} else {
/* Check if default mutex attributes: */
if (mutex_attr == NULL || *mutex_attr == NULL) {
/* Default to a fast mutex: */
type = MUTEX_TYPE_FAST;
} else if ((*mutex_attr)->m_type >= MUTEX_TYPE_MAX) {
/* Return an invalid argument error: */
ret = EINVAL;
} else {
/* Use the requested mutex type: */
type = (*mutex_attr)->m_type;
}
/* Check no errors so far: */
if (ret == 0) {
if ((pmutex = (pthread_mutex_t) malloc(sizeof(struct pthread_mutex))) == NULL) {
ret = ENOMEM;
} else {
/* Reset the mutex flags: */
pmutex->m_flags = 0;
/* Block signals: */
_thread_kern_sig_block(&status);
/* Process according to mutex type: */
switch (type) {
/* Fast mutex: */
case MUTEX_TYPE_FAST:
/* Nothing to do here. */
break;
/* Counting mutex: */
case MUTEX_TYPE_COUNTING_FAST:
/* Reset the mutex count: */
pmutex->m_data.m_count = 0;
break;
/* Trap invalid mutex types: */
default:
/* Return an invalid argument error: */
ret = EINVAL;
break;
}
if (ret == 0) {
/* Initialise the rest of the mutex: */
_thread_queue_init(&pmutex->m_queue);
pmutex->m_flags |= MUTEX_FLAGS_INITED;
pmutex->m_owner = NULL;
pmutex->m_type = type;
*mutex = pmutex;
} else {
free(pmutex);
*mutex = NULL;
}
/* Unblock signals: */
_thread_kern_sig_unblock(status);
}
}
}
/* Return the completion status: */
return (ret);
}
int
pthread_mutex_destroy(pthread_mutex_t * mutex)
{
int ret = 0;
int status;
if (mutex == NULL || *mutex == NULL) {
ret = EINVAL;
} else {
/* Block signals: */
_thread_kern_sig_block(&status);
/* Process according to mutex type: */
switch ((*mutex)->m_type) {
/* Fast mutex: */
case MUTEX_TYPE_FAST:
/* Nothing to do here. */
break;
/* Counting mutex: */
case MUTEX_TYPE_COUNTING_FAST:
/* Reset the mutex count: */
(*mutex)->m_data.m_count = 0;
break;
/* Trap undefined mutex types: */
default:
/* Return an invalid argument error: */
ret = EINVAL;
break;
}
/* Clean up the mutex in case that others want to use it: */
_thread_queue_init(&(*mutex)->m_queue);
(*mutex)->m_owner = NULL;
(*mutex)->m_flags = 0;
/* Unblock signals: */
_thread_kern_sig_unblock(status);
}
/* Return the completion status: */
return (ret);
}
int
pthread_mutex_trylock(pthread_mutex_t * mutex)
{
int ret = 0;
int status;
if (mutex == NULL || *mutex == NULL) {
ret = EINVAL;
} else {
/* Block signals: */
_thread_kern_sig_block(&status);
/* Process according to mutex type: */
switch ((*mutex)->m_type) {
/* Fast mutex: */
case MUTEX_TYPE_FAST:
/* Check if this mutex is not locked: */
if ((*mutex)->m_owner == NULL) {
/* Lock the mutex for the running thread: */
(*mutex)->m_owner = _thread_run;
} else {
/* Return a busy error: */
ret = EBUSY;
}
break;
/* Counting mutex: */
case MUTEX_TYPE_COUNTING_FAST:
/* Check if this mutex is locked: */
if ((*mutex)->m_owner != NULL) {
/*
* Check if the mutex is locked by the running
* thread:
*/
if ((*mutex)->m_owner == _thread_run) {
/* Increment the lock count: */
(*mutex)->m_data.m_count++;
} else {
/* Return a busy error: */
ret = EBUSY;
}
} else {
/* Lock the mutex for the running thread: */
(*mutex)->m_owner = _thread_run;
}
break;
/* Trap invalid mutex types: */
default:
/* Return an invalid argument error: */
ret = EINVAL;
break;
}
/* Unblock signals: */
_thread_kern_sig_unblock(status);
}
/* Return the completion status: */
return (ret);
}
int
pthread_mutex_lock(pthread_mutex_t * mutex)
{
int ret = 0;
int status;
if (mutex == NULL || *mutex == NULL) {
ret = EINVAL;
} else {
/* Block signals: */
_thread_kern_sig_block(&status);
/* Process according to mutex type: */
switch ((*mutex)->m_type) {
/* Fast mutexes do not check for any error conditions: */
case MUTEX_TYPE_FAST:
/*
* Enter a loop to wait for the mutex to be locked by the
* current thread:
*/
while ((*mutex)->m_owner != _thread_run) {
/* Check if the mutex is not locked: */
if ((*mutex)->m_owner == NULL) {
/* Lock the mutex for this thread: */
(*mutex)->m_owner = _thread_run;
} else {
/*
* Join the queue of threads waiting to lock
* the mutex:
*/
_thread_queue_enq(&(*mutex)->m_queue, _thread_run);
/* Block signals: */
_thread_kern_sched_state(PS_MUTEX_WAIT, __FILE__, __LINE__);
/* Block signals: */
_thread_kern_sig_block(NULL);
}
}
break;
/* Counting mutex: */
case MUTEX_TYPE_COUNTING_FAST:
/*
* Enter a loop to wait for the mutex to be locked by the
* current thread:
*/
while ((*mutex)->m_owner != _thread_run) {
/* Check if the mutex is not locked: */
if ((*mutex)->m_owner == NULL) {
/* Lock the mutex for this thread: */
(*mutex)->m_owner = _thread_run;
/* Reset the lock count for this mutex: */
(*mutex)->m_data.m_count = 0;
} else {
/*
* Join the queue of threads waiting to lock
* the mutex:
*/
_thread_queue_enq(&(*mutex)->m_queue, _thread_run);
/* Block signals: */
_thread_kern_sched_state(PS_MUTEX_WAIT, __FILE__, __LINE__);
/* Block signals: */
_thread_kern_sig_block(NULL);
}
}
/* Increment the lock count for this mutex: */
(*mutex)->m_data.m_count++;
break;
/* Trap invalid mutex types: */
default:
/* Return an invalid argument error: */
ret = EINVAL;
break;
}
/* Unblock signals: */
_thread_kern_sig_unblock(status);
}
/* Return the completion status: */
return (ret);
}
int
pthread_mutex_unlock(pthread_mutex_t * mutex)
{
int ret = 0;
int status;
if (mutex == NULL || *mutex == NULL) {
ret = EINVAL;
} else {
/* Block signals: */
_thread_kern_sig_block(&status);
/* Process according to mutex type: */
switch ((*mutex)->m_type) {
/* Fast mutexes do not check for any error conditions: */
case MUTEX_TYPE_FAST:
/* Check if the running thread is not the owner of the mutex: */
if ((*mutex)->m_owner != _thread_run) {
/* Return an invalid argument error: */
ret = EINVAL;
}
/*
* Get the next thread from the queue of threads waiting on
* the mutex:
*/
else if (((*mutex)->m_owner = _thread_queue_deq(&(*mutex)->m_queue)) != NULL) {
/* Allow the new owner of the mutex to run: */
PTHREAD_NEW_STATE((*mutex)->m_owner,PS_RUNNING);
}
break;
/* Counting mutex: */
case MUTEX_TYPE_COUNTING_FAST:
/* Check if the running thread is not the owner of the mutex: */
if ((*mutex)->m_owner != _thread_run) {
/* Return an invalid argument error: */
ret = EINVAL;
}
/* Check if there are still counts: */
else if ((*mutex)->m_data.m_count) {
/* Decrement the count: */
(*mutex)->m_data.m_count--;
}
/*
* Get the next thread from the queue of threads waiting on
* the mutex:
*/
else if (((*mutex)->m_owner = _thread_queue_deq(&(*mutex)->m_queue)) != NULL) {
/* Allow the new owner of the mutex to run: */
PTHREAD_NEW_STATE((*mutex)->m_owner,PS_RUNNING);
}
break;
/* Trap invalid mutex types: */
default:
/* Return an invalid argument error: */
ret = EINVAL;
break;
}
/* Unblock signals: */
_thread_kern_sig_unblock(status);
}
/* Return the completion status: */
return (ret);
}
#endif
|