summaryrefslogtreecommitdiffstats
path: root/util/qemu-thread-posix.c
blob: 74a3023f3e5929eb5750492bbeef79cfa2418f86 (plain)
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
/*
 * Wrappers around mutex/cond/thread functions
 *
 * Copyright Red Hat, Inc. 2009
 *
 * Author:
 *  Marcelo Tosatti <mtosatti@redhat.com>
 *
 * This work is licensed under the terms of the GNU GPL, version 2 or later.
 * See the COPYING file in the top-level directory.
 *
 */
#include "qemu/osdep.h"
#ifdef __linux__
#include <sys/syscall.h>
#include <linux/futex.h>
#endif
#include "qemu/thread.h"
#include "qemu/atomic.h"
#include "qemu/notify.h"

static bool name_threads;

void qemu_thread_naming(bool enable)
{
    name_threads = enable;

#ifndef CONFIG_THREAD_SETNAME_BYTHREAD
    /* This is a debugging option, not fatal */
    if (enable) {
        fprintf(stderr, "qemu: thread naming not supported on this host\n");
    }
#endif
}

static void error_exit(int err, const char *msg)
{
    fprintf(stderr, "qemu: %s: %s\n", msg, strerror(err));
    abort();
}

void qemu_mutex_init(QemuMutex *mutex)
{
    int err;

    err = pthread_mutex_init(&mutex->lock, NULL);
    if (err)
        error_exit(err, __func__);
}

void qemu_mutex_destroy(QemuMutex *mutex)
{
    int err;

    err = pthread_mutex_destroy(&mutex->lock);
    if (err)
        error_exit(err, __func__);
}

void qemu_mutex_lock(QemuMutex *mutex)
{
    int err;

    err = pthread_mutex_lock(&mutex->lock);
    if (err)
        error_exit(err, __func__);
}

int qemu_mutex_trylock(QemuMutex *mutex)
{
    return pthread_mutex_trylock(&mutex->lock);
}

void qemu_mutex_unlock(QemuMutex *mutex)
{
    int err;

    err = pthread_mutex_unlock(&mutex->lock);
    if (err)
        error_exit(err, __func__);
}

void qemu_cond_init(QemuCond *cond)
{
    int err;

    err = pthread_cond_init(&cond->cond, NULL);
    if (err)
        error_exit(err, __func__);
}

void qemu_cond_destroy(QemuCond *cond)
{
    int err;

    err = pthread_cond_destroy(&cond->cond);
    if (err)
        error_exit(err, __func__);
}

void qemu_cond_signal(QemuCond *cond)
{
    int err;

    err = pthread_cond_signal(&cond->cond);
    if (err)
        error_exit(err, __func__);
}

void qemu_cond_broadcast(QemuCond *cond)
{
    int err;

    err = pthread_cond_broadcast(&cond->cond);
    if (err)
        error_exit(err, __func__);
}

void qemu_cond_wait(QemuCond *cond, QemuMutex *mutex)
{
    int err;

    err = pthread_cond_wait(&cond->cond, &mutex->lock);
    if (err)
        error_exit(err, __func__);
}

void qemu_sem_init(QemuSemaphore *sem, int init)
{
    int rc;

#if defined(__APPLE__) || defined(__NetBSD__)
    rc = pthread_mutex_init(&sem->lock, NULL);
    if (rc != 0) {
        error_exit(rc, __func__);
    }
    rc = pthread_cond_init(&sem->cond, NULL);
    if (rc != 0) {
        error_exit(rc, __func__);
    }
    if (init < 0) {
        error_exit(EINVAL, __func__);
    }
    sem->count = init;
#else
    rc = sem_init(&sem->sem, 0, init);
    if (rc < 0) {
        error_exit(errno, __func__);
    }
#endif
}

void qemu_sem_destroy(QemuSemaphore *sem)
{
    int rc;

#if defined(__APPLE__) || defined(__NetBSD__)
    rc = pthread_cond_destroy(&sem->cond);
    if (rc < 0) {
        error_exit(rc, __func__);
    }
    rc = pthread_mutex_destroy(&sem->lock);
    if (rc < 0) {
        error_exit(rc, __func__);
    }
#else
    rc = sem_destroy(&sem->sem);
    if (rc < 0) {
        error_exit(errno, __func__);
    }
#endif
}

void qemu_sem_post(QemuSemaphore *sem)
{
    int rc;

#if defined(__APPLE__) || defined(__NetBSD__)
    pthread_mutex_lock(&sem->lock);
    if (sem->count == UINT_MAX) {
        rc = EINVAL;
    } else {
        sem->count++;
        rc = pthread_cond_signal(&sem->cond);
    }
    pthread_mutex_unlock(&sem->lock);
    if (rc != 0) {
        error_exit(rc, __func__);
    }
#else
    rc = sem_post(&sem->sem);
    if (rc < 0) {
        error_exit(errno, __func__);
    }
#endif
}

static void compute_abs_deadline(struct timespec *ts, int ms)
{
    struct timeval tv;
    gettimeofday(&tv, NULL);
    ts->tv_nsec = tv.tv_usec * 1000 + (ms % 1000) * 1000000;
    ts->tv_sec = tv.tv_sec + ms / 1000;
    if (ts->tv_nsec >= 1000000000) {
        ts->tv_sec++;
        ts->tv_nsec -= 1000000000;
    }
}

int qemu_sem_timedwait(QemuSemaphore *sem, int ms)
{
    int rc;
    struct timespec ts;

#if defined(__APPLE__) || defined(__NetBSD__)
    rc = 0;
    compute_abs_deadline(&ts, ms);
    pthread_mutex_lock(&sem->lock);
    while (sem->count == 0) {
        rc = pthread_cond_timedwait(&sem->cond, &sem->lock, &ts);
        if (rc == ETIMEDOUT) {
            break;
        }
        if (rc != 0) {
            error_exit(rc, __func__);
        }
    }
    if (rc != ETIMEDOUT) {
        --sem->count;
    }
    pthread_mutex_unlock(&sem->lock);
    return (rc == ETIMEDOUT ? -1 : 0);
#else
    if (ms <= 0) {
        /* This is cheaper than sem_timedwait.  */
        do {
            rc = sem_trywait(&sem->sem);
        } while (rc == -1 && errno == EINTR);
        if (rc == -1 && errno == EAGAIN) {
            return -1;
        }
    } else {
        compute_abs_deadline(&ts, ms);
        do {
            rc = sem_timedwait(&sem->sem, &ts);
        } while (rc == -1 && errno == EINTR);
        if (rc == -1 && errno == ETIMEDOUT) {
            return -1;
        }
    }
    if (rc < 0) {
        error_exit(errno, __func__);
    }
    return 0;
#endif
}

void qemu_sem_wait(QemuSemaphore *sem)
{
    int rc;

#if defined(__APPLE__) || defined(__NetBSD__)
    pthread_mutex_lock(&sem->lock);
    while (sem->count == 0) {
        rc = pthread_cond_wait(&sem->cond, &sem->lock);
        if (rc != 0) {
            error_exit(rc, __func__);
        }
    }
    --sem->count;
    pthread_mutex_unlock(&sem->lock);
#else
    do {
        rc = sem_wait(&sem->sem);
    } while (rc == -1 && errno == EINTR);
    if (rc < 0) {
        error_exit(errno, __func__);
    }
#endif
}

#ifdef __linux__
#define futex(...)              syscall(__NR_futex, __VA_ARGS__)

static inline void futex_wake(QemuEvent *ev, int n)
{
    futex(ev, FUTEX_WAKE, n, NULL, NULL, 0);
}

static inline void futex_wait(QemuEvent *ev, unsigned val)
{
    while (futex(ev, FUTEX_WAIT, (int) val, NULL, NULL, 0)) {
        switch (errno) {
        case EWOULDBLOCK:
            return;
        case EINTR:
            break; /* get out of switch and retry */
        default:
            abort();
        }
    }
}
#else
static inline void futex_wake(QemuEvent *ev, int n)
{
    pthread_mutex_lock(&ev->lock);
    if (n == 1) {
        pthread_cond_signal(&ev->cond);
    } else {
        pthread_cond_broadcast(&ev->cond);
    }
    pthread_mutex_unlock(&ev->lock);
}

static inline void futex_wait(QemuEvent *ev, unsigned val)
{
    pthread_mutex_lock(&ev->lock);
    if (ev->value == val) {
        pthread_cond_wait(&ev->cond, &ev->lock);
    }
    pthread_mutex_unlock(&ev->lock);
}
#endif

/* Valid transitions:
 * - free->set, when setting the event
 * - busy->set, when setting the event, followed by futex_wake
 * - set->free, when resetting the event
 * - free->busy, when waiting
 *
 * set->busy does not happen (it can be observed from the outside but
 * it really is set->free->busy).
 *
 * busy->free provably cannot happen; to enforce it, the set->free transition
 * is done with an OR, which becomes a no-op if the event has concurrently
 * transitioned to free or busy.
 */

#define EV_SET         0
#define EV_FREE        1
#define EV_BUSY       -1

void qemu_event_init(QemuEvent *ev, bool init)
{
#ifndef __linux__
    pthread_mutex_init(&ev->lock, NULL);
    pthread_cond_init(&ev->cond, NULL);
#endif

    ev->value = (init ? EV_SET : EV_FREE);
}

void qemu_event_destroy(QemuEvent *ev)
{
#ifndef __linux__
    pthread_mutex_destroy(&ev->lock);
    pthread_cond_destroy(&ev->cond);
#endif
}

void qemu_event_set(QemuEvent *ev)
{
    if (atomic_mb_read(&ev->value) != EV_SET) {
        if (atomic_xchg(&ev->value, EV_SET) == EV_BUSY) {
            /* There were waiters, wake them up.  */
            futex_wake(ev, INT_MAX);
        }
    }
}

void qemu_event_reset(QemuEvent *ev)
{
    if (atomic_mb_read(&ev->value) == EV_SET) {
        /*
         * If there was a concurrent reset (or even reset+wait),
         * do nothing.  Otherwise change EV_SET->EV_FREE.
         */
        atomic_or(&ev->value, EV_FREE);
    }
}

void qemu_event_wait(QemuEvent *ev)
{
    unsigned value;

    value = atomic_mb_read(&ev->value);
    if (value != EV_SET) {
        if (value == EV_FREE) {
            /*
             * Leave the event reset and tell qemu_event_set that there
             * are waiters.  No need to retry, because there cannot be
             * a concurrent busy->free transition.  After the CAS, the
             * event will be either set or busy.
             */
            if (atomic_cmpxchg(&ev->value, EV_FREE, EV_BUSY) == EV_SET) {
                return;
            }
        }
        futex_wait(ev, EV_BUSY);
    }
}

static pthread_key_t exit_key;

union NotifierThreadData {
    void *ptr;
    NotifierList list;
};
QEMU_BUILD_BUG_ON(sizeof(union NotifierThreadData) != sizeof(void *));

void qemu_thread_atexit_add(Notifier *notifier)
{
    union NotifierThreadData ntd;
    ntd.ptr = pthread_getspecific(exit_key);
    notifier_list_add(&ntd.list, notifier);
    pthread_setspecific(exit_key, ntd.ptr);
}

void qemu_thread_atexit_remove(Notifier *notifier)
{
    union NotifierThreadData ntd;
    ntd.ptr = pthread_getspecific(exit_key);
    notifier_remove(notifier);
    pthread_setspecific(exit_key, ntd.ptr);
}

static void qemu_thread_atexit_run(void *arg)
{
    union NotifierThreadData ntd = { .ptr = arg };
    notifier_list_notify(&ntd.list, NULL);
}

static void __attribute__((constructor)) qemu_thread_atexit_init(void)
{
    pthread_key_create(&exit_key, qemu_thread_atexit_run);
}


/* Attempt to set the threads name; note that this is for debug, so
 * we're not going to fail if we can't set it.
 */
static void qemu_thread_set_name(QemuThread *thread, const char *name)
{
#ifdef CONFIG_PTHREAD_SETNAME_NP
    pthread_setname_np(thread->thread, name);
#endif
}

void qemu_thread_create(QemuThread *thread, const char *name,
                       void *(*start_routine)(void*),
                       void *arg, int mode)
{
    sigset_t set, oldset;
    int err;
    pthread_attr_t attr;

    err = pthread_attr_init(&attr);
    if (err) {
        error_exit(err, __func__);
    }
    if (mode == QEMU_THREAD_DETACHED) {
        err = pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
        if (err) {
            error_exit(err, __func__);
        }
    }

    /* Leave signal handling to the iothread.  */
    sigfillset(&set);
    pthread_sigmask(SIG_SETMASK, &set, &oldset);
    err = pthread_create(&thread->thread, &attr, start_routine, arg);
    if (err)
        error_exit(err, __func__);

    if (name_threads) {
        qemu_thread_set_name(thread, name);
    }

    pthread_sigmask(SIG_SETMASK, &oldset, NULL);

    pthread_attr_destroy(&attr);
}

void qemu_thread_get_self(QemuThread *thread)
{
    thread->thread = pthread_self();
}

bool qemu_thread_is_self(QemuThread *thread)
{
   return pthread_equal(pthread_self(), thread->thread);
}

void qemu_thread_exit(void *retval)
{
    pthread_exit(retval);
}

void *qemu_thread_join(QemuThread *thread)
{
    int err;
    void *ret;

    err = pthread_join(thread->thread, &ret);
    if (err) {
        error_exit(err, __func__);
    }
    return ret;
}
OpenPOWER on IntegriCloud