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
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
|
/*
* 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 AUTHOR 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.
*
* $FreeBSD$
*/
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <pthread.h>
#include "thr_private.h"
/*
* Prototypes
*/
static pthread_t cond_queue_deq(pthread_cond_t);
static void cond_queue_remove(pthread_cond_t, pthread_t);
static void cond_queue_enq(pthread_cond_t, pthread_t);
static int cond_signal(pthread_cond_t *, int);
static int cond_wait_common(pthread_cond_t *,
pthread_mutex_t *, const struct timespec *);
__weak_reference(_pthread_cond_init, pthread_cond_init);
__weak_reference(_pthread_cond_destroy, pthread_cond_destroy);
__weak_reference(_pthread_cond_wait, pthread_cond_wait);
__weak_reference(_pthread_cond_timedwait, pthread_cond_timedwait);
__weak_reference(_pthread_cond_signal, pthread_cond_signal);
__weak_reference(_pthread_cond_broadcast, pthread_cond_broadcast);
#define COND_LOCK(c) \
do { \
if (umtx_lock(&(c)->c_lock, curthread->thr_id)) \
abort(); \
} while (0)
#define COND_UNLOCK(c) \
do { \
if (umtx_unlock(&(c)->c_lock, curthread->thr_id)) \
abort(); \
} while (0)
/* Reinitialize a condition variable to defaults. */
int
_cond_reinit(pthread_cond_t *cond)
{
if (cond == NULL)
return (EINVAL);
if (*cond == NULL)
return (pthread_cond_init(cond, NULL));
/*
* Initialize the condition variable structure:
*/
TAILQ_INIT(&(*cond)->c_queue);
(*cond)->c_flags = COND_FLAGS_INITED;
(*cond)->c_type = COND_TYPE_FAST;
(*cond)->c_mutex = NULL;
(*cond)->c_seqno = 0;
bzero(&(*cond)->c_lock, sizeof((*cond)->c_lock));
return (0);
}
int
_pthread_cond_init(pthread_cond_t *cond, const pthread_condattr_t *cond_attr)
{
enum pthread_cond_type type;
pthread_cond_t pcond;
if (cond == NULL)
return (EINVAL);
/*
* Check if a pointer to a condition variable attribute
* structure was passed by the caller:
*/
if (cond_attr != NULL && *cond_attr != NULL)
type = (*cond_attr)->c_type;
else
/* Default to a fast condition variable: */
type = COND_TYPE_FAST;
/* Process according to condition variable type: */
switch (type) {
case COND_TYPE_FAST:
break;
default:
return (EINVAL);
break;
}
if ((pcond = (pthread_cond_t)
malloc(sizeof(struct pthread_cond))) == NULL)
return (ENOMEM);
/*
* Initialise the condition variable
* structure:
*/
TAILQ_INIT(&pcond->c_queue);
pcond->c_flags |= COND_FLAGS_INITED;
pcond->c_type = type;
pcond->c_mutex = NULL;
pcond->c_seqno = 0;
bzero(&pcond->c_lock, sizeof(pcond->c_lock));
*cond = pcond;
return (0);
}
int
_pthread_cond_destroy(pthread_cond_t *cond)
{
if (cond == NULL || *cond == NULL)
return (EINVAL);
COND_LOCK(*cond);
/*
* Free the memory allocated for the condition
* variable structure:
*/
free(*cond);
/*
* NULL the caller's pointer now that the condition
* variable has been destroyed:
*/
*cond = NULL;
return (0);
}
int
_pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex)
{
int rval;
rval = cond_wait_common(cond, mutex, NULL);
/* This should never happen. */
if (rval == ETIMEDOUT)
abort();
return (rval);
}
int
_pthread_cond_timedwait(pthread_cond_t * cond, pthread_mutex_t * mutex,
const struct timespec * abstime)
{
if (abstime == NULL || abstime->tv_nsec >= 1000000000)
return (EINVAL);
return (cond_wait_common(cond, mutex, abstime));
}
static int
cond_wait_common(pthread_cond_t * cond, pthread_mutex_t * mutex,
const struct timespec * abstime)
{
int rval = 0;
int done = 0;
int seqno;
int mtxrval;
_thread_enter_cancellation_point();
if (cond == NULL)
return (EINVAL);
/*
* If the condition variable is statically initialized, perform dynamic
* initialization.
*/
if (*cond == NULL && (rval = pthread_cond_init(cond, NULL)) != 0)
return (rval);
COND_LOCK(*cond);
/*
* If the condvar was statically allocated, properly
* initialize the tail queue.
*/
if (((*cond)->c_flags & COND_FLAGS_INITED) == 0) {
TAILQ_INIT(&(*cond)->c_queue);
(*cond)->c_flags |= COND_FLAGS_INITED;
}
/* Process according to condition variable type. */
switch ((*cond)->c_type) {
/* Fast condition variable: */
case COND_TYPE_FAST:
if ((mutex == NULL) || (((*cond)->c_mutex != NULL) &&
((*cond)->c_mutex != *mutex))) {
COND_UNLOCK(*cond);
rval = EINVAL;
break;
}
/* Remember the mutex */
(*cond)->c_mutex = *mutex;
if ((rval = _mutex_cv_unlock(mutex)) != 0) {
if (rval == -1){
printf("foo");
fflush(stdout);
abort();
}
COND_UNLOCK(*cond);
break;
}
/*
* We need to protect the queue operations. It also
* protects c_seqno and the pthread flag fields. This is
* dropped before calling _thread_suspend() and reaquired
* when we return.
*/
_thread_critical_enter(curthread);
/*
* c_seqno is protected.
*/
seqno = (*cond)->c_seqno;
do {
/*
* Queue the running thread on the condition
* variable.
*/
cond_queue_enq(*cond, curthread);
if (curthread->cancelflags & PTHREAD_CANCELLING) {
/*
* POSIX Says that we must relock the mutex
* even if we're being canceled.
*/
_thread_critical_exit(curthread);
COND_UNLOCK(*cond);
_mutex_cv_lock(mutex);
pthread_testcancel();
PANIC("Shouldn't have come back.");
}
PTHREAD_SET_STATE(curthread, PS_COND_WAIT);
_thread_critical_exit(curthread);
COND_UNLOCK(*cond);
rval = _thread_suspend(curthread, (struct timespec *)abstime);
if (rval == -1) {
printf("foo");
fflush(stdout);
abort();
}
COND_LOCK(*cond);
_thread_critical_enter(curthread);
done = (seqno != (*cond)->c_seqno);
/*
* If we timed out, this will remove us from the
* queue. Otherwise, if we were signaled it does
* nothing because this thread won't be on the queue.
*/
cond_queue_remove(*cond, curthread);
} while ((done == 0) && (rval == 0));
/*
* If we timed out someone still may have signaled us
* before we got a chance to run again. We check for
* this by looking to see if our state is RUNNING.
*/
if (rval == EAGAIN) {
if (curthread->state != PS_RUNNING) {
PTHREAD_SET_STATE(curthread, PS_RUNNING);
rval = ETIMEDOUT;
} else
rval = 0;
}
_thread_critical_exit(curthread);
COND_UNLOCK(*cond);
mtxrval = _mutex_cv_lock(mutex);
/*
* If the mutex failed return that error, otherwise we're
* returning ETIMEDOUT.
*/
if (mtxrval == -1) {
printf("foo");
fflush(stdout);
abort();
}
if (mtxrval != 0)
rval = mtxrval;
break;
/* Trap invalid condition variable types: */
default:
COND_UNLOCK(*cond);
rval = EINVAL;
break;
}
_thread_leave_cancellation_point();
return (rval);
}
int
_pthread_cond_signal(pthread_cond_t * cond)
{
return (cond_signal(cond, 0));
}
int
_pthread_cond_broadcast(pthread_cond_t * cond)
{
return (cond_signal(cond, 1));
}
static int
cond_signal(pthread_cond_t * cond, int broadcast)
{
int rval = 0;
pthread_t pthread;
if (cond == NULL)
return (EINVAL);
/*
* If the condition variable is statically initialized, perform dynamic
* initialization.
*/
if (*cond == NULL && (rval = pthread_cond_init(cond, NULL)) != 0)
return (rval);
COND_LOCK(*cond);
/* Process according to condition variable type: */
switch ((*cond)->c_type) {
/* Fast condition variable: */
case COND_TYPE_FAST:
(*cond)->c_seqno++;
/*
* Enter a loop to bring all (or only one) threads off the
* condition queue:
*/
do {
/*
* Wake up the signaled thread. It will be returned
* to us locked, and with signals disabled.
*/
if ((pthread = cond_queue_deq(*cond)) != NULL) {
PTHREAD_NEW_STATE(pthread, PS_RUNNING);
_thread_critical_exit(pthread);
}
} while (broadcast && pthread != NULL);
break;
/* Trap invalid condition variable types: */
default:
rval = EINVAL;
break;
}
COND_UNLOCK(*cond);
return (rval);
}
void
_cond_wait_backout(pthread_t pthread)
{
pthread_cond_t cond;
cond = pthread->data.cond;
if (cond == NULL)
return;
COND_LOCK(cond);
/* Process according to condition variable type: */
switch (cond->c_type) {
/* Fast condition variable: */
case COND_TYPE_FAST:
_thread_critical_enter(curthread);
cond_queue_remove(cond, pthread);
_thread_critical_exit(curthread);
break;
default:
break;
}
COND_UNLOCK(cond);
}
/*
* Dequeue a waiting thread from the head of a condition queue in
* descending priority order.
*/
static pthread_t
cond_queue_deq(pthread_cond_t cond)
{
pthread_t pthread;
while ((pthread = TAILQ_FIRST(&cond->c_queue)) != NULL) {
_thread_critical_enter(pthread);
TAILQ_REMOVE(&cond->c_queue, pthread, sqe);
cond_queue_remove(cond, pthread);
if ((pthread->cancelflags & PTHREAD_CANCELLING) == 0 &&
pthread->state == PS_COND_WAIT)
/*
* Only exit the loop when we find a thread
* that hasn't timed out or been canceled;
* those threads are already running and don't
* need their run state changed.
*/
break;
else
_thread_critical_exit(pthread);
}
return(pthread);
}
/*
* Remove a waiting thread from a condition queue in descending priority
* order.
*/
static void
cond_queue_remove(pthread_cond_t cond, pthread_t pthread)
{
/*
* Because pthread_cond_timedwait() can timeout as well
* as be signaled by another thread, it is necessary to
* guard against removing the thread from the queue if
* it isn't in the queue.
*/
if (pthread->flags & PTHREAD_FLAGS_IN_CONDQ) {
TAILQ_REMOVE(&cond->c_queue, pthread, sqe);
pthread->flags &= ~PTHREAD_FLAGS_IN_CONDQ;
}
/* Check for no more waiters. */
if (TAILQ_FIRST(&cond->c_queue) == NULL)
cond->c_mutex = NULL;
}
/*
* Enqueue a waiting thread to a condition queue in descending priority
* order.
*/
static void
cond_queue_enq(pthread_cond_t cond, pthread_t pthread)
{
pthread_t tid = TAILQ_LAST(&cond->c_queue, cond_head);
char *name;
name = pthread->name ? pthread->name : "unknown";
if ((pthread->flags & PTHREAD_FLAGS_IN_CONDQ) != 0)
_thread_printf(2, "Thread (%s:%u) already on condq\n",
pthread->name, pthread->uniqueid);
if ((pthread->flags & PTHREAD_FLAGS_IN_MUTEXQ) != 0)
_thread_printf(2, "Thread (%s:%u) already on mutexq\n",
pthread->name, pthread->uniqueid);
PTHREAD_ASSERT_NOT_IN_SYNCQ(pthread);
/*
* For the common case of all threads having equal priority,
* we perform a quick check against the priority of the thread
* at the tail of the queue.
*/
if ((tid == NULL) || (pthread->active_priority <= tid->active_priority))
TAILQ_INSERT_TAIL(&cond->c_queue, pthread, sqe);
else {
tid = TAILQ_FIRST(&cond->c_queue);
while (pthread->active_priority <= tid->active_priority)
tid = TAILQ_NEXT(tid, sqe);
TAILQ_INSERT_BEFORE(tid, pthread, sqe);
}
pthread->flags |= PTHREAD_FLAGS_IN_CONDQ;
pthread->data.cond = cond;
}
|