xnu-1228.tar.gz

[apple/xnu.git] / iokit / IOKit / i386 / IOSharedLockImp.h

diff --git a/iokit/IOKit/i386/IOSharedLockImp.h b/iokit/IOKit/i386/IOSharedLockImp.h
index 0478bc429482438269765c2adbefd267389c91a1..ee2bd16d34972e213956c4429f3fb0d35831f12c 100644 (file)
--- a/iokit/IOKit/i386/IOSharedLockImp.h
+++ b/iokit/IOKit/i386/IOSharedLockImp.h
@@ -1,16 +1,19 @@
 /*
  * Copyright (c) 1998-2000 Apple Computer, Inc. All rights reserved.
  *
- * @APPLE_LICENSE_HEADER_START@
- * 
- * Copyright (c) 1999-2003 Apple Computer, Inc.  All Rights Reserved.
+ * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
  * 
  * 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.
+ * compliance with the License. The rights granted to you under the License
+ * may not be used to create, or enable the creation or redistribution of,
+ * unlawful or unlicensed copies of an Apple operating system, or to
+ * circumvent, violate, or enable the circumvention or violation of, any
+ * terms of an Apple operating system software license agreement.
+ * 
+ * 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
@@ -20,7 +23,7 @@
  * Please see the License for the specific language governing rights and
  * limitations under the License.
  * 
- * @APPLE_LICENSE_HEADER_END@
+ * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
  */
 /*
  * Copyright (c) 1998 Apple Computer, Inc.  All rights reserved. 
@@ -52,16 +55,6 @@
 
 #include <architecture/i386/asm_help.h>
 
-// 'Till we're building in kernel
-.macro DISABLE_PREEMPTION
-#ifdef KERNEL
-#endif
-.endmacro
-.macro ENABLE_PREEMPTION
-#ifdef KERNEL
-#endif
-.endmacro
-
 /* 
  * void
  * ev_lock(p)
@@ -75,16 +68,15 @@
 #ifndef KERNEL
 LEAF(_ev_lock, 0)
 LEAF(_IOSpinLock, 0)
-       push    %eax
-       push    %ecx
-       movl    $1, %ecx
-       movl    12(%esp), %eax  
-_spin:
-       xchgl   %ecx,0(%eax)
-       cmp     $0, %ecx
-       jne     _spin
-       pop     %ecx
-       pop     %eax
+       movl            4(%esp), %ecx
+0:
+       xorl            %eax, %eax
+       rep
+       nop             /* pause for hyperthreaded CPU's */
+       lock
+       cmpxchgl        %ecx, (%ecx)
+       jne             0b
+       ret
 END(_ev_lock)
 #endif
 
@@ -97,11 +89,9 @@ END(_ev_lock)
  */
 LEAF(_ev_unlock, 0)
 LEAF(_IOSpinUnlock, 0)
-       push    %eax
-       movl    8(%esp),%eax
-       movl    $0,0(%eax)
-       ENABLE_PREEMPTION()
-       pop     %eax
+       movl            4(%esp), %ecx
+       movl            $0, (%ecx)
+       ret
 END(_ev_unlock)
 
 
@@ -116,14 +106,14 @@ END(_ev_unlock)
 
 LEAF(_ev_try_lock, 0)
 LEAF(_IOTrySpinLock, 0)
-        DISABLE_PREEMPTION()
-       movl    4(%esp), %eax
-   lock;bts    $0, 0(%eax)
-       jb      1f
+        movl            4(%esp), %ecx 
+       xorl            %eax, %eax
+        lock
+        cmpxchgl        %ecx, (%ecx)
+       jne     1f
        movl    $1, %eax                /* yes */
        ret
 1:
-       ENABLE_PREEMPTION()
        xorl    %eax, %eax              /* no */
 END(_ev_try_lock)