iokit/Kernel/IOCommandGate.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,
  21  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  22  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  23  * Please see the License for the specific language governing rights and
  24  * limitations under the License.
  25  *
  26  * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
  27  */
  28 #include <libkern/OSDebug.h>
  29
  30 #include <IOKit/IOCommandGate.h>
  31 #include <IOKit/IOWorkLoop.h>
  32 #include <IOKit/IOReturn.h>
  33 #include <IOKit/IOTimeStamp.h>
  34
  35 #define super IOEventSource
  36
  37 OSDefineMetaClassAndStructors(IOCommandGate, IOEventSource)
  38 OSMetaClassDefineReservedUnused(IOCommandGate, 0);
  39 OSMetaClassDefineReservedUnused(IOCommandGate, 1);
  40 OSMetaClassDefineReservedUnused(IOCommandGate, 2);
  41 OSMetaClassDefineReservedUnused(IOCommandGate, 3);
  42 OSMetaClassDefineReservedUnused(IOCommandGate, 4);
  43 OSMetaClassDefineReservedUnused(IOCommandGate, 5);
  44 OSMetaClassDefineReservedUnused(IOCommandGate, 6);
  45 OSMetaClassDefineReservedUnused(IOCommandGate, 7);
  46
  47 bool IOCommandGate::checkForWork() { return false; }
  48
  49 bool IOCommandGate::init(OSObject *inOwner, Action inAction)
  50 {
  51     return super::init(inOwner, (IOEventSource::Action) inAction);
  52 }
  53
  54 IOCommandGate *
  55 IOCommandGate::commandGate(OSObject *inOwner, Action inAction)
  56 {
  57     IOCommandGate *me = new IOCommandGate;
  58
  59     if (me && !me->init(inOwner, inAction)) {
  60         me->release();
  61         return 0;
  62     }
  63
  64     return me;
  65 }
  66
  67 /* virtual */ void IOCommandGate::disable()
  68 {
  69     if (workLoop && !workLoop->inGate())
  70         OSReportWithBacktrace("IOCommandGate::disable() called when not gated");
  71
  72     super::disable();
  73 }
  74
  75 /* virtual */ void IOCommandGate::enable()
  76 {
  77     if (workLoop) {
  78         closeGate();
  79         super::enable();
  80         wakeupGate(&enabled, /* oneThread */ false); // Unblock sleeping threads
  81         openGate();
  82     }
  83 }
  84
  85 /* virtual */ void IOCommandGate::free()
  86 {
  87     setWorkLoop(0);
  88     super::free();
  89 }
  90
  91 /* virtual */ void IOCommandGate::setWorkLoop(IOWorkLoop *inWorkLoop)
  92 {
  93     uintptr_t *sleepersP = (uintptr_t *) &reserved;
  94     if (!inWorkLoop && workLoop) {              // tearing down
  95         closeGate();
  96         *sleepersP |= 1;
  97         while (*sleepersP >> 1) {
  98             thread_wakeup_with_result(&enabled, THREAD_INTERRUPTED);
  99             sleepGate(sleepersP, THREAD_UNINT);
 100         }
 101         *sleepersP = 0;
 102         openGate();
 103     }
 104     else
 105
 106     super::setWorkLoop(inWorkLoop);
 107 }
 108
 109 IOReturn IOCommandGate::runCommand(void *arg0, void *arg1,
 110                                    void *arg2, void *arg3)
 111 {
 112     return runAction((Action) action, arg0, arg1, arg2, arg3);
 113 }
 114
 115 IOReturn IOCommandGate::attemptCommand(void *arg0, void *arg1,
 116                                        void *arg2, void *arg3)
 117 {
 118     return attemptAction((Action) action, arg0, arg1, arg2, arg3);
 119 }
 120
 121 IOReturn IOCommandGate::runAction(Action inAction,
 122                                   void *arg0, void *arg1,
 123                                   void *arg2, void *arg3)
 124 {
 125     if (!inAction)
 126         return kIOReturnBadArgument;
 127
 128     IOTimeStampConstant(IODBG_CMDQ(IOCMDQ_ACTION),
 129                         (unsigned int) inAction, (unsigned int) owner);
 130
 131     // closeGate is recursive needn't worry if we already hold the lock.
 132     closeGate();
 133
 134     // If the command gate is disabled and we aren't on the workloop thread
 135     // itself then sleep until we get enabled.
 136     IOReturn res;
 137     if (!workLoop->onThread()) {
 138         while (!enabled) {
 139             uintptr_t *sleepersP = (uintptr_t *) &reserved;
 140
 141             *sleepersP += 2;
 142             IOReturn res = sleepGate(&enabled, THREAD_ABORTSAFE);
 143             *sleepersP -= 2;
 144
 145             bool wakeupTearDown = (*sleepersP & 1);
 146             if (res || wakeupTearDown) {
 147                 openGate();
 148
 149                  if (wakeupTearDown)
 150                      commandWakeup(sleepersP);  // No further resources used
 151
 152                 return kIOReturnAborted;
 153             }
 154         }
 155     }
 156
 157     // Must be gated and on the work loop or enabled
 158     res = (*inAction)(owner, arg0, arg1, arg2, arg3);
 159     openGate();
 160
 161     return res;
 162 }
 163
 164 IOReturn IOCommandGate::attemptAction(Action inAction,
 165                                       void *arg0, void *arg1,
 166                                       void *arg2, void *arg3)
 167 {
 168     IOReturn res;
 169
 170     if (!inAction)
 171         return kIOReturnBadArgument;
 172
 173     // Try to close the gate if can't get return immediately.
 174     if (!tryCloseGate())
 175         return kIOReturnCannotLock;
 176
 177     // If the command gate is disabled then sleep until we get a wakeup
 178     if (!workLoop->onThread() && !enabled)
 179         res = kIOReturnNotPermitted;
 180     else {
 181         IOTimeStampConstant(IODBG_CMDQ(IOCMDQ_ACTION),
 182                             (unsigned int) inAction, (unsigned int) owner);
 183
 184         res = (*inAction)(owner, arg0, arg1, arg2, arg3);
 185     }
 186
 187     openGate();
 188
 189     return res;
 190 }
 191
 192 IOReturn IOCommandGate::commandSleep(void *event, UInt32 interruptible)
 193 {
 194     if (!workLoop->inGate())
 195         return kIOReturnNotPermitted;
 196
 197     return sleepGate(event, interruptible);
 198 }
 199
 200 void IOCommandGate::commandWakeup(void *event, bool oneThread)
 201 {
 202     wakeupGate(event, oneThread);
 203 }