--- xnu/xnu-344.2/iokit/Kernel/IOLocks.cpp
+++ xnu/xnu-123.5/iokit/Kernel/IOLocks.cpp
@@ -49,6 +49,8 @@
 
 void	IOLockInitWithState( IOLock * lock, IOLockState state)
 {
+    mutex_init( lock, ETAP_IO_AHA);
+
     if( state == kIOLockStateLocked)
         IOLockLock( lock);
 }
@@ -94,7 +96,7 @@
     if( lock->thread == IOThreadSelf())
         lock->count++;
     else {
-        mutex_lock( lock->mutex );
+        _mutex_lock( lock->mutex );
         assert( lock->thread == 0 );
         assert( lock->count == 0 );
         lock->thread = IOThreadSelf();
@@ -110,7 +112,7 @@
         lock->count++;
 	return( true );
     } else {
-        if( mutex_try( lock->mutex )) {
+        if( _mutex_try( lock->mutex )) {
             assert( lock->thread == 0 );
             assert( lock->count == 0 );
             lock->thread = IOThreadSelf();
@@ -149,16 +151,21 @@
     assert(lock->thread == IOThreadSelf());
     assert(lock->count == 1 || interType == THREAD_UNINT);
     
+    assert_wait((event_t) event, (int) interType);
     lock->count = 0;
     lock->thread = 0;
-    res = thread_sleep_mutex((event_t) event, lock->mutex, (int) interType);
-
-    // Must re-establish the recursive lock no matter why we woke up
-    // otherwise we would potentially leave the return path corrupted.
-    assert(lock->thread == 0);
-    assert(lock->count == 0);
-    lock->thread = IOThreadSelf();
-    lock->count = count;
+    mutex_unlock(lock->mutex);
+    
+    res = thread_block(0);
+
+    if (THREAD_AWAKENED == res) {
+        _mutex_lock(lock->mutex);
+        assert(lock->thread == 0);
+        assert(lock->count == 0);
+        lock->thread = IOThreadSelf();
+        lock->count = count;
+    }
+
     return res;
 }