libkern/gen/OSSpinLock.c

   1 /*
   2  * Copyright (c) 2020 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. The rights granted to you under the License
  10  * may not be used to create, or enable the creation or redistribution of,
  11  * unlawful or unlicensed copies of an Apple operating system, or to
  12  * circumvent, violate, or enable the circumvention or violation of, any
  13  * terms of an Apple operating system software license agreement.
  14  *
  15  * Please obtain a copy of the License at
  16  * http://www.opensource.apple.com/apsl/ and read it before using this file.
  17  *
  18  * The Original Code and all software distributed under the License are
  19  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  20  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  21  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
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  23  * Please see the License for the specific language governing rights and
  24  * limitations under the License.
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  26  * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
  27  */
  28
  29 #include <libkern/OSAtomic.h>
  30 #include <machine/atomic.h>
  31
  32 _Static_assert(sizeof(int) == sizeof(OSSpinLock), "OSSpinLock size mismatch");
  33
  34 void
  35 OSSpinLockUnlock(volatile OSSpinLock *lock)
  36 {
  37         os_atomic_store(lock, 0, release);
  38 }
  39
  40 Boolean
  41 OSSpinLockTry(volatile OSSpinLock *lock)
  42 {
  43         return os_atomic_cmpxchg(lock, 0, 1, acquire);
  44 }