2 files changed, 17 insertions, 126 deletions

diff --git a/include/qemu/thread-win32.h b/include/qemu/thread-win32.h
index 5fb6541..4c4a261 100644
--- a/include/qemu/thread-win32.h
+++ b/include/qemu/thread-win32.h
@@ -4,8 +4,7 @@
 #include <windows.h>
 
 struct QemuMutex {
-    CRITICAL_SECTION lock;
-    LONG owner;
+    SRWLOCK lock;
 };
 
 typedef struct QemuRecMutex QemuRecMutex;
@@ -19,9 +18,7 @@ int qemu_rec_mutex_trylock(QemuRecMutex *mutex);
 void qemu_rec_mutex_unlock(QemuRecMutex *mutex);
 
 struct QemuCond {
-    LONG waiters, target;
-    HANDLE sema;
-    HANDLE continue_event;
+    CONDITION_VARIABLE var;
 };
 
 struct QemuSemaphore {
diff --git a/util/qemu-thread-win32.c b/util/qemu-thread-win32.c
index 29c3e4d..59befd5 100644
--- a/util/qemu-thread-win32.c
+++ b/util/qemu-thread-win32.c
@@ -10,6 +10,11 @@
  * See the COPYING file in the top-level directory.
  *
  */
+
+#ifndef _WIN32_WINNT
+#define _WIN32_WINNT 0x0600
+#endif
+
 #include "qemu/osdep.h"
 #include "qemu-common.h"
 #include "qemu/thread.h"
@@ -39,44 +44,30 @@ static void error_exit(int err, const char *msg)
 
 void qemu_mutex_init(QemuMutex *mutex)
 {
-    mutex->owner = 0;
-    InitializeCriticalSection(&mutex->lock);
+    InitializeSRWLock(&mutex->lock);
 }
 
 void qemu_mutex_destroy(QemuMutex *mutex)
 {
-    assert(mutex->owner == 0);
-    DeleteCriticalSection(&mutex->lock);
+    InitializeSRWLock(&mutex->lock);
 }
 
 void qemu_mutex_lock(QemuMutex *mutex)
 {
-    EnterCriticalSection(&mutex->lock);
-
-    /* Win32 CRITICAL_SECTIONs are recursive.  Assert that we're not
-     * using them as such.
-     */
-    assert(mutex->owner == 0);
-    mutex->owner = GetCurrentThreadId();
+    AcquireSRWLockExclusive(&mutex->lock);
 }
 
 int qemu_mutex_trylock(QemuMutex *mutex)
 {
     int owned;
 
-    owned = TryEnterCriticalSection(&mutex->lock);
-    if (owned) {
-        assert(mutex->owner == 0);
-        mutex->owner = GetCurrentThreadId();
-    }
+    owned = TryAcquireSRWLockExclusive(&mutex->lock);
     return !owned;
 }
 
 void qemu_mutex_unlock(QemuMutex *mutex)
 {
-    assert(mutex->owner == GetCurrentThreadId());
-    mutex->owner = 0;
-    LeaveCriticalSection(&mutex->lock);
+    ReleaseSRWLockExclusive(&mutex->lock);
 }
 
 void qemu_rec_mutex_init(QemuRecMutex *mutex)
@@ -107,124 +98,27 @@ void qemu_rec_mutex_unlock(QemuRecMutex *mutex)
 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);
 }
 
 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;
+    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__);
-    }
+    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);
+    WakeAllConditionVariable(&cond->var);
 }
 
 void qemu_cond_wait(QemuCond *cond, QemuMutex *mutex)
 {
-    /*
-     * 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);
+    SleepConditionVariableSRW(&cond->var, &mutex->lock, INFINITE, 0);
 }
 
 void qemu_sem_init(QemuSemaphore *sem, int init)