--- xnu/xnu-201/iokit/Kernel/IOLocks.cpp
+++ xnu/xnu-517.3.15/iokit/Kernel/IOLocks.cpp
@@ -3,19 +3,22 @@
  *
  * @APPLE_LICENSE_HEADER_START@
  * 
- * The contents of this file constitute Original Code as defined in and
- * are subject to the Apple Public Source License Version 1.1 (the
- * "License").  You may not use this file except in compliance with the
- * License.  Please obtain a copy of the License at
- * http://www.apple.com/publicsource and read it before using this file.
- * 
- * This Original Code and all software distributed under the License are
- * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
+ * Copyright (c) 1999-2003 Apple Computer, Inc.  All Rights Reserved.
+ * 
+ * This file contains Original Code and/or Modifications of Original Code
+ * as defined in and that are subject to the Apple Public Source License
+ * Version 2.0 (the 'License'). You may not use this file except in
+ * compliance with the License. Please obtain a copy of the License at
+ * http://www.opensource.apple.com/apsl/ and read it before using this
+ * file.
+ * 
+ * The Original Code and all software distributed under the License are
+ * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
- * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
- * License for the specific language governing rights and limitations
- * under the License.
+ * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
+ * Please see the License for the specific language governing rights and
+ * limitations under the License.
  * 
  * @APPLE_LICENSE_HEADER_END@
  */
@@ -149,21 +152,16 @@
     assert(lock->thread == IOThreadSelf());
     assert(lock->count == 1 || interType == THREAD_UNINT);
     
-    assert_wait((event_t) event, (int) interType);
     lock->count = 0;
     lock->thread = 0;
-    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;
-    }
-
+    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;
     return res;
 }