* See the COPYING file in the top-level directory.
*
*/
+
+#include "qemu/osdep.h"
#include "qemu-common.h"
#include "qemu/thread.h"
+#include "qemu/notify.h"
+#include "qemu-thread-common.h"
#include <process.h>
-#include <assert.h>
-#include <limits.h>
static bool name_threads;
{
/* But note we don't actually name them on Windows yet */
name_threads = enable;
+
+ fprintf(stderr, "qemu: thread naming not supported on this host\n");
}
static void error_exit(int err, const char *msg)
void qemu_mutex_init(QemuMutex *mutex)
{
- mutex->owner = 0;
- InitializeCriticalSection(&mutex->lock);
+ InitializeSRWLock(&mutex->lock);
+ qemu_mutex_post_init(mutex);
}
void qemu_mutex_destroy(QemuMutex *mutex)
{
- assert(mutex->owner == 0);
- DeleteCriticalSection(&mutex->lock);
+ assert(mutex->initialized);
+ mutex->initialized = false;
+ InitializeSRWLock(&mutex->lock);
}
-void qemu_mutex_lock(QemuMutex *mutex)
+void qemu_mutex_lock_impl(QemuMutex *mutex, const char *file, const int line)
{
- EnterCriticalSection(&mutex->lock);
-
- /* Win32 CRITICAL_SECTIONs are recursive. Assert that we're not
- * using them as such.
- */
- assert(mutex->owner == 0);
- mutex->owner = GetCurrentThreadId();
+ assert(mutex->initialized);
+ qemu_mutex_pre_lock(mutex, file, line);
+ AcquireSRWLockExclusive(&mutex->lock);
+ qemu_mutex_post_lock(mutex, file, line);
}
-int qemu_mutex_trylock(QemuMutex *mutex)
+int qemu_mutex_trylock_impl(QemuMutex *mutex, const char *file, const int line)
{
int owned;
- owned = TryEnterCriticalSection(&mutex->lock);
+ assert(mutex->initialized);
+ owned = TryAcquireSRWLockExclusive(&mutex->lock);
if (owned) {
- assert(mutex->owner == 0);
- mutex->owner = GetCurrentThreadId();
+ qemu_mutex_post_lock(mutex, file, line);
+ return 0;
}
- return !owned;
+ return -EBUSY;
+}
+
+void qemu_mutex_unlock_impl(QemuMutex *mutex, const char *file, const int line)
+{
+ assert(mutex->initialized);
+ qemu_mutex_pre_unlock(mutex, file, line);
+ ReleaseSRWLockExclusive(&mutex->lock);
+}
+
+void qemu_rec_mutex_init(QemuRecMutex *mutex)
+{
+ InitializeCriticalSection(&mutex->lock);
+ mutex->initialized = true;
+}
+
+void qemu_rec_mutex_destroy(QemuRecMutex *mutex)
+{
+ assert(mutex->initialized);
+ mutex->initialized = false;
+ DeleteCriticalSection(&mutex->lock);
+}
+
+void qemu_rec_mutex_lock_impl(QemuRecMutex *mutex, const char *file, int line)
+{
+ assert(mutex->initialized);
+ EnterCriticalSection(&mutex->lock);
}
-void qemu_mutex_unlock(QemuMutex *mutex)
+int qemu_rec_mutex_trylock_impl(QemuRecMutex *mutex, const char *file, int line)
{
- assert(mutex->owner == GetCurrentThreadId());
- mutex->owner = 0;
+ assert(mutex->initialized);
+ return !TryEnterCriticalSection(&mutex->lock);
+}
+
+void qemu_rec_mutex_unlock(QemuRecMutex *mutex)
+{
+ assert(mutex->initialized);
LeaveCriticalSection(&mutex->lock);
}
void qemu_cond_init(QemuCond *cond)
{
memset(cond, 0, sizeof(*cond));
-
- cond->sema = CreateSemaphore(NULL, 0, LONG_MAX, NULL);
- if (!cond->sema) {
- error_exit(GetLastError(), __func__);
- }
- cond->continue_event = CreateEvent(NULL, /* security */
- FALSE, /* auto-reset */
- FALSE, /* not signaled */
- NULL); /* name */
- if (!cond->continue_event) {
- error_exit(GetLastError(), __func__);
- }
+ InitializeConditionVariable(&cond->var);
+ cond->initialized = true;
}
void qemu_cond_destroy(QemuCond *cond)
{
- BOOL result;
- result = CloseHandle(cond->continue_event);
- if (!result) {
- error_exit(GetLastError(), __func__);
- }
- cond->continue_event = 0;
- result = CloseHandle(cond->sema);
- if (!result) {
- error_exit(GetLastError(), __func__);
- }
- cond->sema = 0;
+ assert(cond->initialized);
+ cond->initialized = false;
+ InitializeConditionVariable(&cond->var);
}
void qemu_cond_signal(QemuCond *cond)
{
- DWORD result;
-
- /*
- * Signal only when there are waiters. cond->waiters is
- * incremented by pthread_cond_wait under the external lock,
- * so we are safe about that.
- */
- if (cond->waiters == 0) {
- return;
- }
-
- /*
- * Waiting threads decrement it outside the external lock, but
- * only if another thread is executing pthread_cond_broadcast and
- * has the mutex. So, it also cannot be decremented concurrently
- * with this particular access.
- */
- cond->target = cond->waiters - 1;
- result = SignalObjectAndWait(cond->sema, cond->continue_event,
- INFINITE, FALSE);
- if (result == WAIT_ABANDONED || result == WAIT_FAILED) {
- error_exit(GetLastError(), __func__);
- }
+ assert(cond->initialized);
+ WakeConditionVariable(&cond->var);
}
void qemu_cond_broadcast(QemuCond *cond)
{
- BOOLEAN result;
- /*
- * As in pthread_cond_signal, access to cond->waiters and
- * cond->target is locked via the external mutex.
- */
- if (cond->waiters == 0) {
- return;
- }
-
- cond->target = 0;
- result = ReleaseSemaphore(cond->sema, cond->waiters, NULL);
- if (!result) {
- error_exit(GetLastError(), __func__);
- }
-
- /*
- * At this point all waiters continue. Each one takes its
- * slice of the semaphore. Now it's our turn to wait: Since
- * the external mutex is held, no thread can leave cond_wait,
- * yet. For this reason, we can be sure that no thread gets
- * a chance to eat *more* than one slice. OTOH, it means
- * that the last waiter must send us a wake-up.
- */
- WaitForSingleObject(cond->continue_event, INFINITE);
+ assert(cond->initialized);
+ WakeAllConditionVariable(&cond->var);
}
-void qemu_cond_wait(QemuCond *cond, QemuMutex *mutex)
+void qemu_cond_wait_impl(QemuCond *cond, QemuMutex *mutex, const char *file, const int line)
{
- /*
- * This access is protected under the mutex.
- */
- cond->waiters++;
-
- /*
- * Unlock external mutex and wait for signal.
- * NOTE: we've held mutex locked long enough to increment
- * waiters count above, so there's no problem with
- * leaving mutex unlocked before we wait on semaphore.
- */
- qemu_mutex_unlock(mutex);
- WaitForSingleObject(cond->sema, INFINITE);
-
- /* Now waiters must rendez-vous with the signaling thread and
- * let it continue. For cond_broadcast this has heavy contention
- * and triggers thundering herd. So goes life.
- *
- * Decrease waiters count. The mutex is not taken, so we have
- * to do this atomically.
- *
- * All waiters contend for the mutex at the end of this function
- * until the signaling thread relinquishes it. To ensure
- * each waiter consumes exactly one slice of the semaphore,
- * the signaling thread stops until it is told by the last
- * waiter that it can go on.
- */
- if (InterlockedDecrement(&cond->waiters) == cond->target) {
- SetEvent(cond->continue_event);
- }
-
- qemu_mutex_lock(mutex);
+ assert(cond->initialized);
+ qemu_mutex_pre_unlock(mutex, file, line);
+ SleepConditionVariableSRW(&cond->var, &mutex->lock, INFINITE, 0);
+ qemu_mutex_post_lock(mutex, file, line);
}
void qemu_sem_init(QemuSemaphore *sem, int init)
{
/* Manual reset. */
sem->sema = CreateSemaphore(NULL, init, LONG_MAX, NULL);
+ sem->initialized = true;
}
void qemu_sem_destroy(QemuSemaphore *sem)
{
+ assert(sem->initialized);
+ sem->initialized = false;
CloseHandle(sem->sema);
}
void qemu_sem_post(QemuSemaphore *sem)
{
+ assert(sem->initialized);
ReleaseSemaphore(sem->sema, 1, NULL);
}
int qemu_sem_timedwait(QemuSemaphore *sem, int ms)
{
- int rc = WaitForSingleObject(sem->sema, ms);
+ int rc;
+
+ assert(sem->initialized);
+ rc = WaitForSingleObject(sem->sema, ms);
if (rc == WAIT_OBJECT_0) {
return 0;
}
void qemu_sem_wait(QemuSemaphore *sem)
{
+ assert(sem->initialized);
if (WaitForSingleObject(sem->sema, INFINITE) != WAIT_OBJECT_0) {
error_exit(GetLastError(), __func__);
}
}
+/* Wrap a Win32 manual-reset event with a fast userspace path. The idea
+ * is to reset the Win32 event lazily, as part of a test-reset-test-wait
+ * sequence. Such a sequence is, indeed, how QemuEvents are used by
+ * RCU and other subsystems!
+ *
+ * Valid transitions:
+ * - free->set, when setting the event
+ * - busy->set, when setting the event, followed by SetEvent
+ * - 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 (and is faster than cmpxchg).
+ */
+
+#define EV_SET 0
+#define EV_FREE 1
+#define EV_BUSY -1
+
void qemu_event_init(QemuEvent *ev, bool init)
{
/* Manual reset. */
- ev->event = CreateEvent(NULL, TRUE, init, NULL);
+ ev->event = CreateEvent(NULL, TRUE, TRUE, NULL);
+ ev->value = (init ? EV_SET : EV_FREE);
+ ev->initialized = true;
}
void qemu_event_destroy(QemuEvent *ev)
{
+ assert(ev->initialized);
+ ev->initialized = false;
CloseHandle(ev->event);
}
void qemu_event_set(QemuEvent *ev)
{
- SetEvent(ev->event);
+ assert(ev->initialized);
+ /* qemu_event_set has release semantics, but because it *loads*
+ * ev->value we need a full memory barrier here.
+ */
+ smp_mb();
+ if (atomic_read(&ev->value) != EV_SET) {
+ if (atomic_xchg(&ev->value, EV_SET) == EV_BUSY) {
+ /* There were waiters, wake them up. */
+ SetEvent(ev->event);
+ }
+ }
}
void qemu_event_reset(QemuEvent *ev)
{
- ResetEvent(ev->event);
+ unsigned value;
+
+ assert(ev->initialized);
+ value = atomic_read(&ev->value);
+ smp_mb_acquire();
+ if (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)
{
- WaitForSingleObject(ev->event, INFINITE);
+ unsigned value;
+
+ assert(ev->initialized);
+ value = atomic_read(&ev->value);
+ smp_mb_acquire();
+ if (value != EV_SET) {
+ if (value == EV_FREE) {
+ /* qemu_event_set is not yet going to call SetEvent, but we are
+ * going to do another check for EV_SET below when setting EV_BUSY.
+ * At that point it is safe to call WaitForSingleObject.
+ */
+ ResetEvent(ev->event);
+
+ /* Tell qemu_event_set that there are waiters. No need to retry
+ * because there cannot be a concurent 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) {
+ value = EV_SET;
+ } else {
+ value = EV_BUSY;
+ }
+ }
+ if (value == EV_BUSY) {
+ WaitForSingleObject(ev->event, INFINITE);
+ }
+ }
}
struct QemuThreadData {
void *(*start_routine)(void *);
void *arg;
short mode;
+ NotifierList exit;
/* Only used for joinable threads. */
bool exited;
CRITICAL_SECTION cs;
};
+static bool atexit_registered;
+static NotifierList main_thread_exit;
+
static __thread QemuThreadData *qemu_thread_data;
+static void run_main_thread_exit(void)
+{
+ notifier_list_notify(&main_thread_exit, NULL);
+}
+
+void qemu_thread_atexit_add(Notifier *notifier)
+{
+ if (!qemu_thread_data) {
+ if (!atexit_registered) {
+ atexit_registered = true;
+ atexit(run_main_thread_exit);
+ }
+ notifier_list_add(&main_thread_exit, notifier);
+ } else {
+ notifier_list_add(&qemu_thread_data->exit, notifier);
+ }
+}
+
+void qemu_thread_atexit_remove(Notifier *notifier)
+{
+ notifier_remove(notifier);
+}
+
static unsigned __stdcall win32_start_routine(void *arg)
{
QemuThreadData *data = (QemuThreadData *) arg;
void *(*start_routine)(void *) = data->start_routine;
void *thread_arg = data->arg;
- if (data->mode == QEMU_THREAD_DETACHED) {
- g_free(data);
- data = NULL;
- }
qemu_thread_data = data;
qemu_thread_exit(start_routine(thread_arg));
abort();
{
QemuThreadData *data = qemu_thread_data;
- if (data) {
- assert(data->mode != QEMU_THREAD_DETACHED);
+ notifier_list_notify(&data->exit, NULL);
+ if (data->mode == QEMU_THREAD_JOINABLE) {
data->ret = arg;
EnterCriticalSection(&data->cs);
data->exited = true;
LeaveCriticalSection(&data->cs);
+ } else {
+ g_free(data);
}
_endthreadex(0);
}
HANDLE handle;
data = thread->data;
- if (!data) {
+ if (data->mode == QEMU_THREAD_DETACHED) {
return NULL;
}
+
/*
* Because multiple copies of the QemuThread can exist via
* qemu_thread_get_self, we need to store a value that cannot
CloseHandle(handle);
}
ret = data->ret;
- assert(data->mode != QEMU_THREAD_DETACHED);
DeleteCriticalSection(&data->cs);
g_free(data);
return ret;
data->arg = arg;
data->mode = mode;
data->exited = false;
+ notifier_list_init(&data->exit);
if (data->mode != QEMU_THREAD_DETACHED) {
InitializeCriticalSection(&data->cs);
error_exit(GetLastError(), __func__);
}
CloseHandle(hThread);
- thread->data = (mode == QEMU_THREAD_DETACHED) ? NULL : data;
+ thread->data = data;
}
void qemu_thread_get_self(QemuThread *thread)
HANDLE handle;
data = thread->data;
- if (!data) {
+ if (data->mode == QEMU_THREAD_DETACHED) {
return NULL;
}
- assert(data->mode != QEMU_THREAD_DETACHED);
EnterCriticalSection(&data->cs);
if (!data->exited) {
- handle = OpenThread(SYNCHRONIZE | THREAD_SUSPEND_RESUME, FALSE,
- thread->tid);
+ handle = OpenThread(SYNCHRONIZE | THREAD_SUSPEND_RESUME |
+ THREAD_SET_CONTEXT, FALSE, thread->tid);
} else {
handle = NULL;
}
projects / mirror_qemu.git / blobdiff