util/qemu-thread-win32.c

   1 /*
   2  * Win32 implementation for mutex/cond/thread functions
   3  *
   4  * Copyright Red Hat, Inc. 2010
   5  *
   6  * Author:
   7  *  Paolo Bonzini <pbonzini@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
  14 #ifndef _WIN32_WINNT
  15 #define _WIN32_WINNT 0x0600
  16 #endif
  17
  18 #include "qemu/osdep.h"
  19 #include "qemu-common.h"
  20 #include "qemu/thread.h"
  21 #include "qemu/notify.h"
  22 #include "qemu-thread-common.h"
  23 #include <process.h>
  24
  25 static bool name_threads;
  26
  27 void qemu_thread_naming(bool enable)
  28 {
  29     /* But note we don't actually name them on Windows yet */
  30     name_threads = enable;
  31
  32     fprintf(stderr, "qemu: thread naming not supported on this host\n");
  33 }
  34
  35 static void error_exit(int err, const char *msg)
  36 {
  37     char *pstr;
  38
  39     FormatMessage(FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_ALLOCATE_BUFFER,
  40                   NULL, err, 0, (LPTSTR)&pstr, 2, NULL);
  41     fprintf(stderr, "qemu: %s: %s\n", msg, pstr);
  42     LocalFree(pstr);
  43     abort();
  44 }
  45
  46 void qemu_mutex_init(QemuMutex *mutex)
  47 {
  48     InitializeSRWLock(&mutex->lock);
  49     qemu_mutex_post_init(mutex);
  50 }
  51
  52 void qemu_mutex_destroy(QemuMutex *mutex)
  53 {
  54     assert(mutex->initialized);
  55     mutex->initialized = false;
  56     InitializeSRWLock(&mutex->lock);
  57 }
  58
  59 void qemu_mutex_lock_impl(QemuMutex *mutex, const char *file, const int line)
  60 {
  61     assert(mutex->initialized);
  62     qemu_mutex_pre_lock(mutex, file, line);
  63     AcquireSRWLockExclusive(&mutex->lock);
  64     qemu_mutex_post_lock(mutex, file, line);
  65 }
  66
  67 int qemu_mutex_trylock_impl(QemuMutex *mutex, const char *file, const int line)
  68 {
  69     int owned;
  70
  71     assert(mutex->initialized);
  72     owned = TryAcquireSRWLockExclusive(&mutex->lock);
  73     if (owned) {
  74         qemu_mutex_post_lock(mutex, file, line);
  75         return 0;
  76     }
  77     return -EBUSY;
  78 }
  79
  80 void qemu_mutex_unlock_impl(QemuMutex *mutex, const char *file, const int line)
  81 {
  82     assert(mutex->initialized);
  83     qemu_mutex_pre_unlock(mutex, file, line);
  84     ReleaseSRWLockExclusive(&mutex->lock);
  85 }
  86
  87 void qemu_rec_mutex_init(QemuRecMutex *mutex)
  88 {
  89     InitializeCriticalSection(&mutex->lock);
  90     mutex->initialized = true;
  91 }
  92
  93 void qemu_rec_mutex_destroy(QemuRecMutex *mutex)
  94 {
  95     assert(mutex->initialized);
  96     mutex->initialized = false;
  97     DeleteCriticalSection(&mutex->lock);
  98 }
  99
 100 void qemu_rec_mutex_lock(QemuRecMutex *mutex)
 101 {
 102     assert(mutex->initialized);
 103     EnterCriticalSection(&mutex->lock);
 104 }
 105
 106 int qemu_rec_mutex_trylock(QemuRecMutex *mutex)
 107 {
 108     assert(mutex->initialized);
 109     return !TryEnterCriticalSection(&mutex->lock);
 110 }
 111
 112 void qemu_rec_mutex_unlock(QemuRecMutex *mutex)
 113 {
 114     assert(mutex->initialized);
 115     LeaveCriticalSection(&mutex->lock);
 116 }
 117
 118 void qemu_cond_init(QemuCond *cond)
 119 {
 120     memset(cond, 0, sizeof(*cond));
 121     InitializeConditionVariable(&cond->var);
 122     cond->initialized = true;
 123 }
 124
 125 void qemu_cond_destroy(QemuCond *cond)
 126 {
 127     assert(cond->initialized);
 128     cond->initialized = false;
 129     InitializeConditionVariable(&cond->var);
 130 }
 131
 132 void qemu_cond_signal(QemuCond *cond)
 133 {
 134     assert(cond->initialized);
 135     WakeConditionVariable(&cond->var);
 136 }
 137
 138 void qemu_cond_broadcast(QemuCond *cond)
 139 {
 140     assert(cond->initialized);
 141     WakeAllConditionVariable(&cond->var);
 142 }
 143
 144 void qemu_cond_wait_impl(QemuCond *cond, QemuMutex *mutex, const char *file, const int line)
 145 {
 146     assert(cond->initialized);
 147     qemu_mutex_pre_unlock(mutex, file, line);
 148     SleepConditionVariableSRW(&cond->var, &mutex->lock, INFINITE, 0);
 149     qemu_mutex_post_lock(mutex, file, line);
 150 }
 151
 152 void qemu_sem_init(QemuSemaphore *sem, int init)
 153 {
 154     /* Manual reset.  */
 155     sem->sema = CreateSemaphore(NULL, init, LONG_MAX, NULL);
 156     sem->initialized = true;
 157 }
 158
 159 void qemu_sem_destroy(QemuSemaphore *sem)
 160 {
 161     assert(sem->initialized);
 162     sem->initialized = false;
 163     CloseHandle(sem->sema);
 164 }
 165
 166 void qemu_sem_post(QemuSemaphore *sem)
 167 {
 168     assert(sem->initialized);
 169     ReleaseSemaphore(sem->sema, 1, NULL);
 170 }
 171
 172 int qemu_sem_timedwait(QemuSemaphore *sem, int ms)
 173 {
 174     int rc;
 175
 176     assert(sem->initialized);
 177     rc = WaitForSingleObject(sem->sema, ms);
 178     if (rc == WAIT_OBJECT_0) {
 179         return 0;
 180     }
 181     if (rc != WAIT_TIMEOUT) {
 182         error_exit(GetLastError(), __func__);
 183     }
 184     return -1;
 185 }
 186
 187 void qemu_sem_wait(QemuSemaphore *sem)
 188 {
 189     assert(sem->initialized);
 190     if (WaitForSingleObject(sem->sema, INFINITE) != WAIT_OBJECT_0) {
 191         error_exit(GetLastError(), __func__);
 192     }
 193 }
 194
 195 /* Wrap a Win32 manual-reset event with a fast userspace path.  The idea
 196  * is to reset the Win32 event lazily, as part of a test-reset-test-wait
 197  * sequence.  Such a sequence is, indeed, how QemuEvents are used by
 198  * RCU and other subsystems!
 199  *
 200  * Valid transitions:
 201  * - free->set, when setting the event
 202  * - busy->set, when setting the event, followed by SetEvent
 203  * - set->free, when resetting the event
 204  * - free->busy, when waiting
 205  *
 206  * set->busy does not happen (it can be observed from the outside but
 207  * it really is set->free->busy).
 208  *
 209  * busy->free provably cannot happen; to enforce it, the set->free transition
 210  * is done with an OR, which becomes a no-op if the event has concurrently
 211  * transitioned to free or busy (and is faster than cmpxchg).
 212  */
 213
 214 #define EV_SET         0
 215 #define EV_FREE        1
 216 #define EV_BUSY       -1
 217
 218 void qemu_event_init(QemuEvent *ev, bool init)
 219 {
 220     /* Manual reset.  */
 221     ev->event = CreateEvent(NULL, TRUE, TRUE, NULL);
 222     ev->value = (init ? EV_SET : EV_FREE);
 223     ev->initialized = true;
 224 }
 225
 226 void qemu_event_destroy(QemuEvent *ev)
 227 {
 228     assert(ev->initialized);
 229     ev->initialized = false;
 230     CloseHandle(ev->event);
 231 }
 232
 233 void qemu_event_set(QemuEvent *ev)
 234 {
 235     assert(ev->initialized);
 236     /* qemu_event_set has release semantics, but because it *loads*
 237      * ev->value we need a full memory barrier here.
 238      */
 239     smp_mb();
 240     if (atomic_read(&ev->value) != EV_SET) {
 241         if (atomic_xchg(&ev->value, EV_SET) == EV_BUSY) {
 242             /* There were waiters, wake them up.  */
 243             SetEvent(ev->event);
 244         }
 245     }
 246 }
 247
 248 void qemu_event_reset(QemuEvent *ev)
 249 {
 250     unsigned value;
 251
 252     assert(ev->initialized);
 253     value = atomic_read(&ev->value);
 254     smp_mb_acquire();
 255     if (value == EV_SET) {
 256         /* If there was a concurrent reset (or even reset+wait),
 257          * do nothing.  Otherwise change EV_SET->EV_FREE.
 258          */
 259         atomic_or(&ev->value, EV_FREE);
 260     }
 261 }
 262
 263 void qemu_event_wait(QemuEvent *ev)
 264 {
 265     unsigned value;
 266
 267     assert(ev->initialized);
 268     value = atomic_read(&ev->value);
 269     smp_mb_acquire();
 270     if (value != EV_SET) {
 271         if (value == EV_FREE) {
 272             /* qemu_event_set is not yet going to call SetEvent, but we are
 273              * going to do another check for EV_SET below when setting EV_BUSY.
 274              * At that point it is safe to call WaitForSingleObject.
 275              */
 276             ResetEvent(ev->event);
 277
 278             /* Tell qemu_event_set that there are waiters.  No need to retry
 279              * because there cannot be a concurent busy->free transition.
 280              * After the CAS, the event will be either set or busy.
 281              */
 282             if (atomic_cmpxchg(&ev->value, EV_FREE, EV_BUSY) == EV_SET) {
 283                 value = EV_SET;
 284             } else {
 285                 value = EV_BUSY;
 286             }
 287         }
 288         if (value == EV_BUSY) {
 289             WaitForSingleObject(ev->event, INFINITE);
 290         }
 291     }
 292 }
 293
 294 struct QemuThreadData {
 295     /* Passed to win32_start_routine.  */
 296     void             *(*start_routine)(void *);
 297     void             *arg;
 298     short             mode;
 299     NotifierList      exit;
 300
 301     /* Only used for joinable threads. */
 302     bool              exited;
 303     void             *ret;
 304     CRITICAL_SECTION  cs;
 305 };
 306
 307 static bool atexit_registered;
 308 static NotifierList main_thread_exit;
 309
 310 static __thread QemuThreadData *qemu_thread_data;
 311
 312 static void run_main_thread_exit(void)
 313 {
 314     notifier_list_notify(&main_thread_exit, NULL);
 315 }
 316
 317 void qemu_thread_atexit_add(Notifier *notifier)
 318 {
 319     if (!qemu_thread_data) {
 320         if (!atexit_registered) {
 321             atexit_registered = true;
 322             atexit(run_main_thread_exit);
 323         }
 324         notifier_list_add(&main_thread_exit, notifier);
 325     } else {
 326         notifier_list_add(&qemu_thread_data->exit, notifier);
 327     }
 328 }
 329
 330 void qemu_thread_atexit_remove(Notifier *notifier)
 331 {
 332     notifier_remove(notifier);
 333 }
 334
 335 static unsigned __stdcall win32_start_routine(void *arg)
 336 {
 337     QemuThreadData *data = (QemuThreadData *) arg;
 338     void *(*start_routine)(void *) = data->start_routine;
 339     void *thread_arg = data->arg;
 340
 341     qemu_thread_data = data;
 342     qemu_thread_exit(start_routine(thread_arg));
 343     abort();
 344 }
 345
 346 void qemu_thread_exit(void *arg)
 347 {
 348     QemuThreadData *data = qemu_thread_data;
 349
 350     notifier_list_notify(&data->exit, NULL);
 351     if (data->mode == QEMU_THREAD_JOINABLE) {
 352         data->ret = arg;
 353         EnterCriticalSection(&data->cs);
 354         data->exited = true;
 355         LeaveCriticalSection(&data->cs);
 356     } else {
 357         g_free(data);
 358     }
 359     _endthreadex(0);
 360 }
 361
 362 void *qemu_thread_join(QemuThread *thread)
 363 {
 364     QemuThreadData *data;
 365     void *ret;
 366     HANDLE handle;
 367
 368     data = thread->data;
 369     if (data->mode == QEMU_THREAD_DETACHED) {
 370         return NULL;
 371     }
 372
 373     /*
 374      * Because multiple copies of the QemuThread can exist via
 375      * qemu_thread_get_self, we need to store a value that cannot
 376      * leak there.  The simplest, non racy way is to store the TID,
 377      * discard the handle that _beginthreadex gives back, and
 378      * get another copy of the handle here.
 379      */
 380     handle = qemu_thread_get_handle(thread);
 381     if (handle) {
 382         WaitForSingleObject(handle, INFINITE);
 383         CloseHandle(handle);
 384     }
 385     ret = data->ret;
 386     DeleteCriticalSection(&data->cs);
 387     g_free(data);
 388     return ret;
 389 }
 390
 391 void qemu_thread_create(QemuThread *thread, const char *name,
 392                        void *(*start_routine)(void *),
 393                        void *arg, int mode)
 394 {
 395     HANDLE hThread;
 396     struct QemuThreadData *data;
 397
 398     data = g_malloc(sizeof *data);
 399     data->start_routine = start_routine;
 400     data->arg = arg;
 401     data->mode = mode;
 402     data->exited = false;
 403     notifier_list_init(&data->exit);
 404
 405     if (data->mode != QEMU_THREAD_DETACHED) {
 406         InitializeCriticalSection(&data->cs);
 407     }
 408
 409     hThread = (HANDLE) _beginthreadex(NULL, 0, win32_start_routine,
 410                                       data, 0, &thread->tid);
 411     if (!hThread) {
 412         error_exit(GetLastError(), __func__);
 413     }
 414     CloseHandle(hThread);
 415     thread->data = data;
 416 }
 417
 418 void qemu_thread_get_self(QemuThread *thread)
 419 {
 420     thread->data = qemu_thread_data;
 421     thread->tid = GetCurrentThreadId();
 422 }
 423
 424 HANDLE qemu_thread_get_handle(QemuThread *thread)
 425 {
 426     QemuThreadData *data;
 427     HANDLE handle;
 428
 429     data = thread->data;
 430     if (data->mode == QEMU_THREAD_DETACHED) {
 431         return NULL;
 432     }
 433
 434     EnterCriticalSection(&data->cs);
 435     if (!data->exited) {
 436         handle = OpenThread(SYNCHRONIZE | THREAD_SUSPEND_RESUME |
 437                             THREAD_SET_CONTEXT, FALSE, thread->tid);
 438     } else {
 439         handle = NULL;
 440     }
 441     LeaveCriticalSection(&data->cs);
 442     return handle;
 443 }
 444
 445 bool qemu_thread_is_self(QemuThread *thread)
 446 {
 447     return GetCurrentThreadId() == thread->tid;
 448 }