iokit/Kernel/IOSyncer.cpp

   1 /*
   2  * Copyright (c) 1998-2000 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,
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  23  * Please see the License for the specific language governing rights and
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  26  * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
  27  */
  28 /* IOSyncer.cpp created by wgulland on 2000-02-02 */
  29
  30 #include <IOKit/IOLib.h>
  31 #include <IOKit/IOSyncer.h>
  32
  33 OSDefineMetaClassAndStructors(IOSyncer, OSObject)
  34
  35 IOSyncer * IOSyncer::create(bool twoRetains)
  36 {
  37     IOSyncer * me = new IOSyncer;
  38
  39     if (me && !me->init(twoRetains)) {
  40         me->release();
  41         return 0;
  42     }
  43
  44     return me;
  45 }
  46
  47 bool IOSyncer::init(bool twoRetains)
  48 {
  49     if (!OSObject::init())
  50         return false;
  51
  52     if (!(guardLock = IOSimpleLockAlloc()) )
  53         return false;
  54
  55     IOSimpleLockInit(guardLock);
  56
  57     if(twoRetains)
  58         retain();
  59
  60     fResult = kIOReturnSuccess;
  61
  62     reinit();
  63
  64     return true;
  65 }
  66
  67 void IOSyncer::reinit()
  68 {
  69     IOInterruptState is = IOSimpleLockLockDisableInterrupt(guardLock);
  70     threadMustStop = true;
  71     IOSimpleLockUnlockEnableInterrupt(guardLock, is);
  72 }
  73
  74 void IOSyncer::free()
  75 {
  76     // just in case a thread is blocked here:
  77     privateSignal();
  78
  79     if (guardLock != NULL)
  80        IOSimpleLockFree(guardLock);
  81
  82     OSObject::free();
  83 }
  84
  85 IOReturn IOSyncer::wait(bool autoRelease)
  86 {
  87     IOInterruptState is = IOSimpleLockLockDisableInterrupt(guardLock);
  88
  89     if (threadMustStop) {
  90         assert_wait((void *) &threadMustStop, false);
  91         IOSimpleLockUnlockEnableInterrupt(guardLock, is);
  92         thread_block(THREAD_CONTINUE_NULL);
  93     }
  94     else
  95         IOSimpleLockUnlockEnableInterrupt(guardLock, is);
  96
  97     IOReturn result = fResult;  // Pick up before auto deleting!
  98
  99     if(autoRelease)
 100         release();
 101
 102     return result;
 103 }
 104
 105 void IOSyncer::signal(IOReturn res, bool autoRelease)
 106 {
 107     fResult = res;
 108     privateSignal();
 109     if(autoRelease)
 110         release();
 111 }
 112
 113 void IOSyncer::privateSignal()
 114 {
 115     if (threadMustStop) {
 116          IOInterruptState is = IOSimpleLockLockDisableInterrupt(guardLock);
 117          threadMustStop = false;
 118          thread_wakeup_one((void *) &threadMustStop);
 119          IOSimpleLockUnlockEnableInterrupt(guardLock, is);
 120     }
 121 }