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