/*
* Win32 implementation for mutex/cond/thread functions
*
* Copyright Red Hat, Inc. 2010
*
* Author:
* Paolo Bonzini <pbonzini@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"
#include "qemu/thread.h"
#include "qemu/notify.h"
#include "qemu-thread-common.h"
#include <process.h>
static bool name_threads;
typedef HRESULT (WINAPI *pSetThreadDescription) (HANDLE hThread,
PCWSTR lpThreadDescription);
static pSetThreadDescription SetThreadDescriptionFunc;
static HMODULE kernel32_module;
static bool load_set_thread_description(void)
{
static gsize _init_once = 0;
if (g_once_init_enter(&_init_once)) {
kernel32_module = LoadLibrary("kernel32.dll");
if (kernel32_module) {
SetThreadDescriptionFunc =
(pSetThreadDescription)GetProcAddress(kernel32_module,
"SetThreadDescription");
if (!SetThreadDescriptionFunc) {
FreeLibrary(kernel32_module);
}
}
g_once_init_leave(&_init_once, 1);
}
return !!SetThreadDescriptionFunc;
}
void qemu_thread_naming(bool enable)
{
name_threads = enable;
if (enable && !load_set_thread_description()) {
fprintf(stderr, "qemu: thread naming not supported on this host\n");
name_threads = false;
}
}
static void error_exit(int err, const char *msg)
{
char *pstr;
FormatMessage(FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_ALLOCATE_BUFFER,
NULL, err, 0, (LPTSTR)&pstr, 2, NULL);
fprintf(stderr, "qemu: %s: %s\n", msg, pstr);
LocalFree(pstr);
abort();
}
void qemu_mutex_init(QemuMutex *mutex)
{
InitializeSRWLock(&mutex->lock);
qemu_mutex_post_init(mutex);
}
void qemu_mutex_destroy(QemuMutex *mutex)
{
assert(mutex->initialized);
mutex->initialized = false;
InitializeSRWLock(&mutex->lock);
}
void qemu_mutex_lock_impl(QemuMutex *mutex, const char *file, const int line)
{
assert(mutex->initialized);
qemu_mutex_pre_lock(mutex, file, line);
AcquireSRWLockExclusive(&mutex->lock);
qemu_mutex_post_lock(mutex, file, line);
}
int qemu_mutex_trylock_impl(QemuMutex *mutex, const char *file, const int line)
{
int owned;
assert(mutex->initialized);
owned = TryAcquireSRWLockExclusive(&mutex->lock);
if (owned) {
qemu_mutex_post_lock(mutex, file, line);
return 0;
}
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);
}
int qemu_rec_mutex_trylock_impl(QemuRecMutex *mutex, const char *file, int line)
{
assert(mutex->initialized);
return !TryEnterCriticalSection(&mutex->lock);
}
void qemu_rec_mutex_unlock_impl(QemuRecMutex *mutex, const char *file, int line)
{
assert(mutex->initialized);
LeaveCriticalSection(&mutex->lock);
}
void qemu_cond_init(QemuCond *cond)
{
memset(cond, 0, sizeof(*cond));
InitializeConditionVariable(&cond->var);
cond->initialized = true;
}
void qemu_cond_destroy(QemuCond *cond)
{
assert(cond->initialized);
cond->initialized = false;
InitializeConditionVariable(&cond->var);
}
void qemu_cond_signal(QemuCond *cond)
{
assert(cond->initialized);
WakeConditionVariable(&cond->var);
}
void qemu_cond_broadcast(QemuCond *cond)
{
assert(cond->initialized);
WakeAllConditionVariable(&cond->var);
}
void qemu_cond_wait_impl(QemuCond *cond, QemuMutex *mutex, const char *file, const int line)
{
assert(cond->initialized);
qemu_mutex_pre_unlock(mutex, file, line);
SleepConditionVariableSRW(&cond->var, &mutex->lock, INFINITE, 0);
qemu_mutex_post_lock(mutex, file, line);
}
bool qemu_cond_timedwait_impl(QemuCond *cond, QemuMutex *mutex, int ms,
const char *file, const int line)
{
int rc = 0;
assert(cond->initialized);
trace_qemu_mutex_unlock(mutex, file, line);
if (!SleepConditionVariableSRW(&cond->var, &mutex->lock, ms, 0)) {
rc = GetLastError();
}
trace_qemu_mutex_locked(mutex, file, line);
if (rc && rc != ERROR_TIMEOUT) {
error_exit(rc, __func__);
}
return rc != ERROR_TIMEOUT;
}
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;
assert(sem->initialized);
rc = WaitForSingleObject(sem->sema, ms);
if (rc == WAIT_OBJECT_0) {
return 0;
}
if (rc != WAIT_TIMEOUT) {
error_exit(GetLastError(), __func__);
}
return -1;
}
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, 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)
{
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 (qatomic_read(&ev->value) != EV_SET) {
if (qatomic_xchg(&ev->value, EV_SET) == EV_BUSY) {
/* There were waiters, wake them up. */
SetEvent(ev->event);
}
}
}
void qemu_event_reset(QemuEvent *ev)
{
unsigned value;
assert(ev->initialized);
value = qatomic_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.
*/
qatomic_or(&ev->value, EV_FREE);
}
}
void qemu_event_wait(QemuEvent *ev)
{
unsigned value;
assert(ev->initialized);
value = qatomic_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 concurrent busy->free transition.
* After the CAS, the event will be either set or busy.
*/
if (qatomic_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 {
/* Passed to win32_start_routine. */
void *(*start_routine)(void *);
void *arg;
short mode;
NotifierList exit;
/* Only used for joinable threads. */
bool exited;
void *ret;
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;
qemu_thread_data = data;
qemu_thread_exit(start_routine(thread_arg));
abort();
}
void qemu_thread_exit(void *arg)
{
QemuThreadData *data = qemu_thread_data;
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);
}
void *qemu_thread_join(QemuThread *thread)
{
QemuThreadData *data;
void *ret;
HANDLE handle;
data = thread->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
* leak there. The simplest, non racy way is to store the TID,
* discard the handle that _beginthreadex gives back, and
* get another copy of the handle here.
*/
handle = qemu_thread_get_handle(thread);
if (handle) {
WaitForSingleObject(handle, INFINITE);
CloseHandle(handle);
}
ret = data->ret;
DeleteCriticalSection(&data->cs);
g_free(data);
return ret;
}
static bool set_thread_description(HANDLE h, const char *name)
{
HRESULT hr;
g_autofree wchar_t *namew = NULL;
if (!load_set_thread_description()) {
return false;
}
namew = g_utf8_to_utf16(name, -1, NULL, NULL, NULL);
if (!namew) {
return false;
}
hr = SetThreadDescriptionFunc(h, namew);
return SUCCEEDED(hr);
}
void qemu_thread_create(QemuThread *thread, const char *name,
void *(*start_routine)(void *),
void *arg, int mode)
{
HANDLE hThread;
struct QemuThreadData *data;
data = g_malloc(sizeof *data);
data->start_routine = start_routine;
data->arg = arg;
data->mode = mode;
data->exited = false;
notifier_list_init(&data->exit);
if (data->mode != QEMU_THREAD_DETACHED) {
InitializeCriticalSection(&data->cs);
}
hThread = (HANDLE) _beginthreadex(NULL, 0, win32_start_routine,
data, 0, &thread->tid);
if (!hThread) {
error_exit(GetLastError(), __func__);
}
if (name_threads && name && !set_thread_description(hThread, name)) {
fprintf(stderr, "qemu: failed to set thread description: %s\n", name);
}
CloseHandle(hThread);
thread->data = data;
}
int qemu_thread_set_affinity(QemuThread *thread, unsigned long *host_cpus,
unsigned long nbits)
{
return -ENOSYS;
}
int qemu_thread_get_affinity(QemuThread *thread, unsigned long **host_cpus,
unsigned long *nbits)
{
return -ENOSYS;
}
void qemu_thread_get_self(QemuThread *thread)
{
thread->data = qemu_thread_data;
thread->tid = GetCurrentThreadId();
}
HANDLE qemu_thread_get_handle(QemuThread *thread)
{
QemuThreadData *data;
HANDLE handle;
data = thread->data;
if (data->mode == QEMU_THREAD_DETACHED) {
return NULL;
}
EnterCriticalSection(&data->cs);
if (!data->exited) {
handle = OpenThread(SYNCHRONIZE | THREAD_SUSPEND_RESUME |
THREAD_SET_CONTEXT, FALSE, thread->tid);
} else {
handle = NULL;
}
LeaveCriticalSection(&data->cs);
return handle;
}
bool qemu_thread_is_self(QemuThread *thread)
{
return GetCurrentThreadId() == thread->tid;
}
