i think it works

code/kernel/ke_mutex.c

@@ -0,0 +1,69 @@
+// ke_mutex.c - binary ownership mutex
+#include "ke_mutex.h"
+#include "ke_thread.h"
+#include "ke_sched.h"
+#include "mm_virt.h"
+#include "ob_object.h"
+
+static void MutexDestroy(OBJECT* obj) { (void)obj; }
+
+KSTATUS MutexCreate(MUTEX **out) {
+    if (!out) return STATUS_INVALID_PARAMETER;
+    MUTEX* m = (MUTEX *)ObAllocateObject(ObjectTypeMutex, sizeof(MUTEX));
+    if (!m)  return STATUS_NO_MEMORY;
+    m->Header.Destroy = MutexDestroy;
+    m->Lock  = (SPINLOCK)SPINLOCK_INIT;
+    m->Owner = (struct THREAD *)0;
+    LIST_INIT(&m->WaitList);
+    *out = m;
+    return STATUS_SUCCESS;
+}
+
+KSTATUS KeAcquireMutex(MUTEX* mutex) {
+    if (!mutex) return STATUS_INVALID_PARAMETER;
+    THREAD* self = KeCurrentThread();
+
+    for (;;) {
+        KeAcquireSpinlock(&mutex->Lock);
+        if (!mutex->Owner) {
+            mutex->Owner = self;
+            KeReleaseSpinlock(&mutex->Lock);
+            return STATUS_SUCCESS;
+        }
+        // Already owned - add self to wait list and block.
+        ListInsertTail(&mutex->WaitList, &self->SchedulerLink);
+        KeReleaseSpinlock(&mutex->Lock);
+        KeBlockThread(self, &mutex->Header);
+        // KeBlockThread calls KeYield; when we return here we've been
+        // unblocked by KeReleaseMutex - loop back and try to own it.
+    }
+}
+
+KSTATUS KeTryAcquireMutex(MUTEX* mutex) {
+    if (!mutex) return STATUS_INVALID_PARAMETER;
+    THREAD* self = KeCurrentThread();
+    KeAcquireSpinlock(&mutex->Lock);
+    if (!mutex->Owner) {
+        mutex->Owner = self;
+        KeReleaseSpinlock(&mutex->Lock);
+        return STATUS_SUCCESS;
+    }
+    KeReleaseSpinlock(&mutex->Lock);
+    return STATUS_FAILURE;
+}
+
+void KeReleaseMutex(MUTEX* mutex) {
+    if (!mutex) return;
+    KeAcquireSpinlock(&mutex->Lock);
+    mutex->Owner = (struct THREAD *)0;
+
+    // Wake the first waiter, if any.
+    if (!LIST_IS_EMPTY(&mutex->WaitList)) {
+        LIST_ENTRY* node = ListPopHead(&mutex->WaitList);
+        THREAD* waiter   = CONTAINING_RECORD(node, THREAD, SchedulerLink);
+        KeReleaseSpinlock(&mutex->Lock);
+        KeUnblockThread(waiter);
+        return;
+    }
+    KeReleaseSpinlock(&mutex->Lock);
+}