David 'Digit' Turner | 086e66e | 2014-02-04 22:24:36 +0100 | [diff] [blame] | 1 | /* |
| 2 | * Wrappers around mutex/cond/thread functions |
| 3 | * |
| 4 | * Copyright Red Hat, Inc. 2009 |
| 5 | * |
| 6 | * Author: |
| 7 | * Marcelo Tosatti <mtosatti@redhat.com> |
| 8 | * |
| 9 | * This work is licensed under the terms of the GNU GPL, version 2 or later. |
| 10 | * See the COPYING file in the top-level directory. |
| 11 | * |
| 12 | */ |
| 13 | #include <stdlib.h> |
| 14 | #include <stdio.h> |
| 15 | #include <errno.h> |
| 16 | #include <time.h> |
| 17 | #include <signal.h> |
| 18 | #include <stdint.h> |
| 19 | #include <string.h> |
| 20 | #include <limits.h> |
| 21 | #include <unistd.h> |
| 22 | #include <sys/time.h> |
| 23 | #ifdef __linux__ |
| 24 | #include <sys/syscall.h> |
| 25 | #include <linux/futex.h> |
| 26 | #endif |
| 27 | #include "qemu/thread.h" |
| 28 | #include "qemu/atomic.h" |
| 29 | |
| 30 | static void error_exit(int err, const char *msg) |
| 31 | { |
| 32 | fprintf(stderr, "qemu: %s: %s\n", msg, strerror(err)); |
| 33 | abort(); |
| 34 | } |
| 35 | |
| 36 | void qemu_mutex_init(QemuMutex *mutex) |
| 37 | { |
| 38 | int err; |
| 39 | pthread_mutexattr_t mutexattr; |
| 40 | |
| 41 | pthread_mutexattr_init(&mutexattr); |
| 42 | pthread_mutexattr_settype(&mutexattr, PTHREAD_MUTEX_ERRORCHECK); |
| 43 | err = pthread_mutex_init(&mutex->lock, &mutexattr); |
| 44 | pthread_mutexattr_destroy(&mutexattr); |
| 45 | if (err) |
| 46 | error_exit(err, __func__); |
| 47 | } |
| 48 | |
| 49 | void qemu_mutex_destroy(QemuMutex *mutex) |
| 50 | { |
| 51 | int err; |
| 52 | |
| 53 | err = pthread_mutex_destroy(&mutex->lock); |
| 54 | if (err) |
| 55 | error_exit(err, __func__); |
| 56 | } |
| 57 | |
| 58 | void qemu_mutex_lock(QemuMutex *mutex) |
| 59 | { |
| 60 | int err; |
| 61 | |
| 62 | err = pthread_mutex_lock(&mutex->lock); |
| 63 | if (err) |
| 64 | error_exit(err, __func__); |
| 65 | } |
| 66 | |
| 67 | int qemu_mutex_trylock(QemuMutex *mutex) |
| 68 | { |
| 69 | return pthread_mutex_trylock(&mutex->lock); |
| 70 | } |
| 71 | |
| 72 | void qemu_mutex_unlock(QemuMutex *mutex) |
| 73 | { |
| 74 | int err; |
| 75 | |
| 76 | err = pthread_mutex_unlock(&mutex->lock); |
| 77 | if (err) |
| 78 | error_exit(err, __func__); |
| 79 | } |
| 80 | |
| 81 | void qemu_cond_init(QemuCond *cond) |
| 82 | { |
| 83 | int err; |
| 84 | |
| 85 | err = pthread_cond_init(&cond->cond, NULL); |
| 86 | if (err) |
| 87 | error_exit(err, __func__); |
| 88 | } |
| 89 | |
| 90 | void qemu_cond_destroy(QemuCond *cond) |
| 91 | { |
| 92 | int err; |
| 93 | |
| 94 | err = pthread_cond_destroy(&cond->cond); |
| 95 | if (err) |
| 96 | error_exit(err, __func__); |
| 97 | } |
| 98 | |
| 99 | void qemu_cond_signal(QemuCond *cond) |
| 100 | { |
| 101 | int err; |
| 102 | |
| 103 | err = pthread_cond_signal(&cond->cond); |
| 104 | if (err) |
| 105 | error_exit(err, __func__); |
| 106 | } |
| 107 | |
| 108 | void qemu_cond_broadcast(QemuCond *cond) |
| 109 | { |
| 110 | int err; |
| 111 | |
| 112 | err = pthread_cond_broadcast(&cond->cond); |
| 113 | if (err) |
| 114 | error_exit(err, __func__); |
| 115 | } |
| 116 | |
| 117 | void qemu_cond_wait(QemuCond *cond, QemuMutex *mutex) |
| 118 | { |
| 119 | int err; |
| 120 | |
| 121 | err = pthread_cond_wait(&cond->cond, &mutex->lock); |
| 122 | if (err) |
| 123 | error_exit(err, __func__); |
| 124 | } |
| 125 | |
| 126 | void qemu_sem_init(QemuSemaphore *sem, int init) |
| 127 | { |
| 128 | int rc; |
| 129 | |
| 130 | #if defined(__APPLE__) || defined(__NetBSD__) |
| 131 | rc = pthread_mutex_init(&sem->lock, NULL); |
| 132 | if (rc != 0) { |
| 133 | error_exit(rc, __func__); |
| 134 | } |
| 135 | rc = pthread_cond_init(&sem->cond, NULL); |
| 136 | if (rc != 0) { |
| 137 | error_exit(rc, __func__); |
| 138 | } |
| 139 | if (init < 0) { |
| 140 | error_exit(EINVAL, __func__); |
| 141 | } |
| 142 | sem->count = init; |
| 143 | #else |
| 144 | rc = sem_init(&sem->sem, 0, init); |
| 145 | if (rc < 0) { |
| 146 | error_exit(errno, __func__); |
| 147 | } |
| 148 | #endif |
| 149 | } |
| 150 | |
| 151 | void qemu_sem_destroy(QemuSemaphore *sem) |
| 152 | { |
| 153 | int rc; |
| 154 | |
| 155 | #if defined(__APPLE__) || defined(__NetBSD__) |
| 156 | rc = pthread_cond_destroy(&sem->cond); |
| 157 | if (rc < 0) { |
| 158 | error_exit(rc, __func__); |
| 159 | } |
| 160 | rc = pthread_mutex_destroy(&sem->lock); |
| 161 | if (rc < 0) { |
| 162 | error_exit(rc, __func__); |
| 163 | } |
| 164 | #else |
| 165 | rc = sem_destroy(&sem->sem); |
| 166 | if (rc < 0) { |
| 167 | error_exit(errno, __func__); |
| 168 | } |
| 169 | #endif |
| 170 | } |
| 171 | |
| 172 | void qemu_sem_post(QemuSemaphore *sem) |
| 173 | { |
| 174 | int rc; |
| 175 | |
| 176 | #if defined(__APPLE__) || defined(__NetBSD__) |
| 177 | pthread_mutex_lock(&sem->lock); |
| 178 | if (sem->count == UINT_MAX) { |
| 179 | rc = EINVAL; |
| 180 | } else { |
| 181 | sem->count++; |
| 182 | rc = pthread_cond_signal(&sem->cond); |
| 183 | } |
| 184 | pthread_mutex_unlock(&sem->lock); |
| 185 | if (rc != 0) { |
| 186 | error_exit(rc, __func__); |
| 187 | } |
| 188 | #else |
| 189 | rc = sem_post(&sem->sem); |
| 190 | if (rc < 0) { |
| 191 | error_exit(errno, __func__); |
| 192 | } |
| 193 | #endif |
| 194 | } |
| 195 | |
| 196 | static void compute_abs_deadline(struct timespec *ts, int ms) |
| 197 | { |
| 198 | struct timeval tv; |
| 199 | gettimeofday(&tv, NULL); |
| 200 | ts->tv_nsec = tv.tv_usec * 1000 + (ms % 1000) * 1000000; |
| 201 | ts->tv_sec = tv.tv_sec + ms / 1000; |
| 202 | if (ts->tv_nsec >= 1000000000) { |
| 203 | ts->tv_sec++; |
| 204 | ts->tv_nsec -= 1000000000; |
| 205 | } |
| 206 | } |
| 207 | |
| 208 | int qemu_sem_timedwait(QemuSemaphore *sem, int ms) |
| 209 | { |
| 210 | int rc; |
| 211 | struct timespec ts; |
| 212 | |
| 213 | #if defined(__APPLE__) || defined(__NetBSD__) |
| 214 | rc = 0; |
| 215 | compute_abs_deadline(&ts, ms); |
| 216 | pthread_mutex_lock(&sem->lock); |
| 217 | while (sem->count == 0) { |
| 218 | rc = pthread_cond_timedwait(&sem->cond, &sem->lock, &ts); |
| 219 | if (rc == ETIMEDOUT) { |
| 220 | break; |
| 221 | } |
| 222 | if (rc != 0) { |
| 223 | error_exit(rc, __func__); |
| 224 | } |
| 225 | } |
| 226 | if (rc != ETIMEDOUT) { |
| 227 | --sem->count; |
| 228 | } |
| 229 | pthread_mutex_unlock(&sem->lock); |
| 230 | return (rc == ETIMEDOUT ? -1 : 0); |
| 231 | #else |
| 232 | if (ms <= 0) { |
| 233 | /* This is cheaper than sem_timedwait. */ |
| 234 | do { |
| 235 | rc = sem_trywait(&sem->sem); |
| 236 | } while (rc == -1 && errno == EINTR); |
| 237 | if (rc == -1 && errno == EAGAIN) { |
| 238 | return -1; |
| 239 | } |
| 240 | } else { |
| 241 | compute_abs_deadline(&ts, ms); |
| 242 | do { |
| 243 | rc = sem_timedwait(&sem->sem, &ts); |
| 244 | } while (rc == -1 && errno == EINTR); |
| 245 | if (rc == -1 && errno == ETIMEDOUT) { |
| 246 | return -1; |
| 247 | } |
| 248 | } |
| 249 | if (rc < 0) { |
| 250 | error_exit(errno, __func__); |
| 251 | } |
| 252 | return 0; |
| 253 | #endif |
| 254 | } |
| 255 | |
| 256 | void qemu_sem_wait(QemuSemaphore *sem) |
| 257 | { |
| 258 | int rc; |
| 259 | |
| 260 | #if defined(__APPLE__) || defined(__NetBSD__) |
| 261 | pthread_mutex_lock(&sem->lock); |
| 262 | while (sem->count == 0) { |
| 263 | rc = pthread_cond_wait(&sem->cond, &sem->lock); |
| 264 | if (rc != 0) { |
| 265 | error_exit(rc, __func__); |
| 266 | } |
| 267 | } |
| 268 | --sem->count; |
| 269 | pthread_mutex_unlock(&sem->lock); |
| 270 | #else |
| 271 | do { |
| 272 | rc = sem_wait(&sem->sem); |
| 273 | } while (rc == -1 && errno == EINTR); |
| 274 | if (rc < 0) { |
| 275 | error_exit(errno, __func__); |
| 276 | } |
| 277 | #endif |
| 278 | } |
| 279 | |
| 280 | #ifdef __linux__ |
| 281 | #define futex(...) syscall(__NR_futex, __VA_ARGS__) |
| 282 | |
| 283 | static inline void futex_wake(QemuEvent *ev, int n) |
| 284 | { |
| 285 | futex(ev, FUTEX_WAKE, n, NULL, NULL, 0); |
| 286 | } |
| 287 | |
| 288 | static inline void futex_wait(QemuEvent *ev, unsigned val) |
| 289 | { |
| 290 | futex(ev, FUTEX_WAIT, (int) val, NULL, NULL, 0); |
| 291 | } |
| 292 | #else |
| 293 | static inline void futex_wake(QemuEvent *ev, int n) |
| 294 | { |
| 295 | if (n == 1) { |
| 296 | pthread_cond_signal(&ev->cond); |
| 297 | } else { |
| 298 | pthread_cond_broadcast(&ev->cond); |
| 299 | } |
| 300 | } |
| 301 | |
| 302 | static inline void futex_wait(QemuEvent *ev, unsigned val) |
| 303 | { |
| 304 | pthread_mutex_lock(&ev->lock); |
| 305 | if (ev->value == val) { |
| 306 | pthread_cond_wait(&ev->cond, &ev->lock); |
| 307 | } |
| 308 | pthread_mutex_unlock(&ev->lock); |
| 309 | } |
| 310 | #endif |
| 311 | |
| 312 | /* Valid transitions: |
| 313 | * - free->set, when setting the event |
| 314 | * - busy->set, when setting the event, followed by futex_wake |
| 315 | * - set->free, when resetting the event |
| 316 | * - free->busy, when waiting |
| 317 | * |
| 318 | * set->busy does not happen (it can be observed from the outside but |
| 319 | * it really is set->free->busy). |
| 320 | * |
| 321 | * busy->free provably cannot happen; to enforce it, the set->free transition |
| 322 | * is done with an OR, which becomes a no-op if the event has concurrently |
| 323 | * transitioned to free or busy. |
| 324 | */ |
| 325 | |
| 326 | #define EV_SET 0 |
| 327 | #define EV_FREE 1 |
| 328 | #define EV_BUSY -1 |
| 329 | |
| 330 | void qemu_event_init(QemuEvent *ev, bool init) |
| 331 | { |
| 332 | #ifndef __linux__ |
| 333 | pthread_mutex_init(&ev->lock, NULL); |
| 334 | pthread_cond_init(&ev->cond, NULL); |
| 335 | #endif |
| 336 | |
| 337 | ev->value = (init ? EV_SET : EV_FREE); |
| 338 | } |
| 339 | |
| 340 | void qemu_event_destroy(QemuEvent *ev) |
| 341 | { |
| 342 | #ifndef __linux__ |
| 343 | pthread_mutex_destroy(&ev->lock); |
| 344 | pthread_cond_destroy(&ev->cond); |
| 345 | #endif |
| 346 | } |
| 347 | |
| 348 | void qemu_event_set(QemuEvent *ev) |
| 349 | { |
| 350 | if (atomic_mb_read(&ev->value) != EV_SET) { |
| 351 | if (atomic_xchg(&ev->value, EV_SET) == EV_BUSY) { |
| 352 | /* There were waiters, wake them up. */ |
| 353 | futex_wake(ev, INT_MAX); |
| 354 | } |
| 355 | } |
| 356 | } |
| 357 | |
| 358 | void qemu_event_reset(QemuEvent *ev) |
| 359 | { |
| 360 | if (atomic_mb_read(&ev->value) == EV_SET) { |
| 361 | /* |
| 362 | * If there was a concurrent reset (or even reset+wait), |
| 363 | * do nothing. Otherwise change EV_SET->EV_FREE. |
| 364 | */ |
| 365 | atomic_or(&ev->value, EV_FREE); |
| 366 | } |
| 367 | } |
| 368 | |
| 369 | void qemu_event_wait(QemuEvent *ev) |
| 370 | { |
| 371 | unsigned value; |
| 372 | |
| 373 | value = atomic_mb_read(&ev->value); |
| 374 | if (value != EV_SET) { |
| 375 | if (value == EV_FREE) { |
| 376 | /* |
| 377 | * Leave the event reset and tell qemu_event_set that there |
| 378 | * are waiters. No need to retry, because there cannot be |
| 379 | * a concurent busy->free transition. After the CAS, the |
| 380 | * event will be either set or busy. |
| 381 | */ |
| 382 | if (atomic_cmpxchg(&ev->value, EV_FREE, EV_BUSY) == EV_SET) { |
| 383 | return; |
| 384 | } |
| 385 | } |
| 386 | futex_wait(ev, EV_BUSY); |
| 387 | } |
| 388 | } |
| 389 | |
| 390 | |
| 391 | void qemu_thread_create(QemuThread *thread, |
| 392 | void *(*start_routine)(void*), |
| 393 | void *arg, int mode) |
| 394 | { |
| 395 | sigset_t set, oldset; |
| 396 | int err; |
| 397 | pthread_attr_t attr; |
| 398 | |
| 399 | err = pthread_attr_init(&attr); |
| 400 | if (err) { |
| 401 | error_exit(err, __func__); |
| 402 | } |
| 403 | if (mode == QEMU_THREAD_DETACHED) { |
| 404 | err = pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED); |
| 405 | if (err) { |
| 406 | error_exit(err, __func__); |
| 407 | } |
| 408 | } |
| 409 | |
| 410 | /* Leave signal handling to the iothread. */ |
| 411 | sigfillset(&set); |
| 412 | pthread_sigmask(SIG_SETMASK, &set, &oldset); |
| 413 | err = pthread_create(&thread->thread, &attr, start_routine, arg); |
| 414 | if (err) |
| 415 | error_exit(err, __func__); |
| 416 | |
| 417 | pthread_sigmask(SIG_SETMASK, &oldset, NULL); |
| 418 | |
| 419 | pthread_attr_destroy(&attr); |
| 420 | } |
| 421 | |
| 422 | void qemu_thread_get_self(QemuThread *thread) |
| 423 | { |
| 424 | thread->thread = pthread_self(); |
| 425 | } |
| 426 | |
| 427 | bool qemu_thread_is_self(QemuThread *thread) |
| 428 | { |
| 429 | return pthread_equal(pthread_self(), thread->thread); |
| 430 | } |
| 431 | |
| 432 | void qemu_thread_exit(void *retval) |
| 433 | { |
| 434 | pthread_exit(retval); |
| 435 | } |
| 436 | |
| 437 | void *qemu_thread_join(QemuThread *thread) |
| 438 | { |
| 439 | int err; |
| 440 | void *ret; |
| 441 | |
| 442 | err = pthread_join(thread->thread, &ret); |
| 443 | if (err) { |
| 444 | error_exit(err, __func__); |
| 445 | } |
| 446 | return ret; |
| 447 | } |