1 files changed, 0 insertions, 129 deletions
diff --git a/util/qemu-thread-win32.c b/util/qemu-thread-win32.c
index a7fe3cc345..ca2e0b512e 100644
--- a/util/qemu-thread-win32.c
+++ b/util/qemu-thread-win32.c
@@ -231,135 +231,6 @@ void qemu_sem_wait(QemuSemaphore *sem)
     }
 }
 
-/* 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);
-
-    /*
-     * Pairs with both qemu_event_reset() and qemu_event_wait().
-     *
-     * 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) {
-        int old = qatomic_xchg(&ev->value, EV_SET);
-
-        /* Pairs with memory barrier after ResetEvent.  */
-        smp_mb__after_rmw();
-        if (old == EV_BUSY) {
-            /* There were waiters, wake them up.  */
-            SetEvent(ev->event);
-        }
-    }
-}
-
-void qemu_event_reset(QemuEvent *ev)
-{
-    assert(ev->initialized);
-
-    /*
-     * If there was a concurrent reset (or even reset+wait),
-     * do nothing.  Otherwise change EV_SET->EV_FREE.
-     */
-    qatomic_or(&ev->value, EV_FREE);
-
-    /*
-     * Order reset before checking the condition in the caller.
-     * Pairs with the first memory barrier in qemu_event_set().
-     */
-    smp_mb__after_rmw();
-}
-
-void qemu_event_wait(QemuEvent *ev)
-{
-    unsigned value;
-
-    assert(ev->initialized);
-
-    /*
-     * qemu_event_wait must synchronize with qemu_event_set even if it does
-     * not go down the slow path, so this load-acquire is needed that
-     * synchronizes with the first memory barrier in qemu_event_set().
-     *
-     * If we do go down the slow path, there is no requirement at all: we
-     * might miss a qemu_event_set() here but ultimately the memory barrier in
-     * qemu_futex_wait() will ensure the check is done correctly.
-     */
-    value = qatomic_load_acquire(&ev->value);
-    if (value != EV_SET) {
-        if (value == EV_FREE) {
-            /*
-             * Here the underlying kernel event is reset, but qemu_event_set is
-             * not yet going to call SetEvent.  However, there will be another
-             * check for EV_SET below when setting EV_BUSY.  At that point it
-             * is safe to call WaitForSingleObject.
-             */
-            ResetEvent(ev->event);
-
-            /*
-             * It is not clear whether ResetEvent provides this barrier; kernel
-             * APIs (KeResetEvent/KeClearEvent) do not.  Better safe than sorry!
-             */
-            smp_mb();
-
-            /*
-             * Leave the event reset and 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) {
-                return;
-            }
-        }
-
-        /*
-         * ev->value is now EV_BUSY.  Since we didn't observe EV_SET,
-         * qemu_event_set() must observe EV_BUSY and call SetEvent().
-         */
-        WaitForSingleObject(ev->event, INFINITE);
-    }
-}
-
 struct QemuThreadData {
     /* Passed to win32_start_routine.  */
     void             *(*start_routine)(void *);