iokit/Kernel/IOWorkLoop.cpp

   1 /*
   2  * Copyright (c) 1998-2000 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * The contents of this file constitute Original Code as defined in and
   7  * are subject to the Apple Public Source License Version 1.1 (the
   8  * "License").  You may not use this file except in compliance with the
   9  * License.  Please obtain a copy of the License at
  10  * http://www.apple.com/publicsource and read it before using this file.
  11  *
  12  * This Original Code and all software distributed under the License are
  13  * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  14  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  15  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  16  * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
  17  * License for the specific language governing rights and limitations
  18  * under the License.
  19  *
  20  * @APPLE_LICENSE_HEADER_END@
  21  */
  22 /*
  23 Copyright (c) 1998 Apple Computer, Inc.  All rights reserved.
  24
  25 HISTORY
  26     1998-7-13   Godfrey van der Linden(gvdl)
  27         Created.
  28 */
  29 #include <IOKit/IOWorkLoop.h>
  30 #include <IOKit/IOEventSource.h>
  31 #include <IOKit/IOInterruptEventSource.h>
  32 #include <IOKit/IOCommandGate.h>
  33 #include <IOKit/IOTimeStamp.h>
  34
  35 #define super OSObject
  36
  37 OSDefineMetaClassAndStructors(IOWorkLoop, OSObject);
  38
  39 // Block of unused functions intended for future use
  40 OSMetaClassDefineReservedUnused(IOWorkLoop, 0);
  41 OSMetaClassDefineReservedUnused(IOWorkLoop, 1);
  42 OSMetaClassDefineReservedUnused(IOWorkLoop, 2);
  43 OSMetaClassDefineReservedUnused(IOWorkLoop, 3);
  44 OSMetaClassDefineReservedUnused(IOWorkLoop, 4);
  45 OSMetaClassDefineReservedUnused(IOWorkLoop, 5);
  46 OSMetaClassDefineReservedUnused(IOWorkLoop, 6);
  47 OSMetaClassDefineReservedUnused(IOWorkLoop, 7);
  48
  49 enum IOWorkLoopState { kLoopRestart = 0x1, kLoopTerminate = 0x2 };
  50 static inline void SETP(void *addr, unsigned int flag)
  51     { unsigned int *num = (unsigned int *) addr; *num |= flag; }
  52 static inline void CLRP(void *addr, unsigned int flag)
  53     { unsigned int *num = (unsigned int *) addr; *num &= ~flag; }
  54 static inline bool ISSETP(void *addr, unsigned int flag)
  55     { unsigned int *num = (unsigned int *) addr; return (*num & flag) != 0; }
  56
  57 #define fFlags loopRestart
  58
  59 void IOWorkLoop::launchThreadMain(void *self)
  60 {
  61     register thread_t mythread = current_thread();
  62
  63     // Make sure that this thread always has a kernel stack
  64     stack_privilege(mythread);
  65     thread_set_cont_arg((int) self);
  66     threadMainContinuation();
  67 }
  68
  69 bool IOWorkLoop::init()
  70 {
  71     // The super init and gateLock allocation MUST be done first
  72     if ( !super::init() )
  73         return false;
  74
  75     if ( !(gateLock = IORecursiveLockAlloc()) )
  76         return false;
  77
  78     if ( !(workToDoLock = IOSimpleLockAlloc()) )
  79         return false;
  80
  81     controlG = IOCommandGate::
  82         commandGate(this, (IOCommandGate::Action) &IOWorkLoop::_maintRequest);
  83     if ( !controlG )
  84         return false;
  85
  86     IOSimpleLockInit(workToDoLock);
  87     workToDo = false;
  88
  89     // Point the controlGate at the workLoop.  Usually addEventSource
  90     // does this automatically.  The problem is in this case addEventSource
  91     // uses the control gate and it has to be bootstrapped.
  92     controlG->setWorkLoop(this);
  93     if (addEventSource(controlG) != kIOReturnSuccess)
  94         return false;
  95
  96     workThread = IOCreateThread(launchThreadMain, (void *) this);
  97     if (!workThread)
  98         return false;
  99
 100     return true;
 101 }
 102
 103 IOWorkLoop *
 104 IOWorkLoop::workLoop()
 105 {
 106     IOWorkLoop *me = new IOWorkLoop;
 107
 108     if (me && !me->init()) {
 109         me->free();
 110         return 0;
 111     }
 112
 113     return me;
 114 }
 115
 116 // Free is called twice:
 117 // First when the atomic retainCount transitions from 1 -> 0
 118 // Secondly when the work loop itself is commiting hari kari
 119 // Hence the each leg of the free must be single threaded.
 120 void IOWorkLoop::free()
 121 {
 122     if (workThread) {
 123         IOInterruptState is;
 124
 125         // If we are here then we must be trying to shut down this work loop
 126         // in this case disable all of the event source, mark the loop for
 127         // as terminating and wakeup the work thread itself and return
 128         // Note: we hold the gate across the entire operation mainly for the
 129         // benefit of our event sources so we can disable them cleanly.
 130         closeGate();
 131
 132         disableAllEventSources();
 133
 134         is = IOSimpleLockLockDisableInterrupt(workToDoLock);
 135         SETP(&fFlags, kLoopTerminate);
 136         thread_wakeup_one((void *) &workToDo);
 137         IOSimpleLockUnlockEnableInterrupt(workToDoLock, is);
 138
 139         openGate();
 140     }
 141     else /* !workThread */ {
 142         IOEventSource *event, *next;
 143
 144         for (event = eventChain; event; event = next) {
 145             next = event->getNext();
 146             event->setWorkLoop(0);
 147             event->setNext(0);
 148             event->release();
 149         }
 150         eventChain = 0;
 151
 152         // Either we have a partial initialisation to clean up
 153         // or we the workThread itself is performing hari-kari.
 154         // either way clean up all of our resources and return.
 155
 156         if (controlG) {
 157             controlG->release();
 158             controlG = 0;
 159         }
 160
 161         if (workToDoLock) {
 162             IOSimpleLockFree(workToDoLock);
 163             workToDoLock = 0;
 164         }
 165
 166         if (gateLock) {
 167             IORecursiveLockFree(gateLock);
 168             gateLock = 0;
 169         }
 170
 171         super::free();
 172     }
 173 }
 174
 175 IOReturn IOWorkLoop::addEventSource(IOEventSource *newEvent)
 176 {
 177     return controlG->runCommand((void *) mAddEvent, (void *) newEvent);
 178 }
 179
 180 IOReturn IOWorkLoop::removeEventSource(IOEventSource *toRemove)
 181 {
 182     return controlG->runCommand((void *) mRemoveEvent, (void *) toRemove);
 183 }
 184
 185 void IOWorkLoop::enableAllEventSources() const
 186 {
 187     IOEventSource *event;
 188
 189     for (event = eventChain; event; event = event->getNext())
 190         event->enable();
 191 }
 192
 193 void IOWorkLoop::disableAllEventSources() const
 194 {
 195     IOEventSource *event;
 196
 197     for (event = eventChain; event; event = event->getNext())
 198         if (event != controlG)  // Don't disable the control gate
 199             event->disable();
 200 }
 201
 202 void IOWorkLoop::enableAllInterrupts() const
 203 {
 204     IOEventSource *event;
 205
 206     for (event = eventChain; event; event = event->getNext())
 207         if (OSDynamicCast(IOInterruptEventSource, event))
 208             event->enable();
 209 }
 210
 211 void IOWorkLoop::disableAllInterrupts() const
 212 {
 213     IOEventSource *event;
 214
 215     for (event = eventChain; event; event = event->getNext())
 216         if (OSDynamicCast(IOInterruptEventSource, event))
 217             event->disable();
 218 }
 219
 220 #if KDEBUG
 221 #define IOTimeClientS()                                                 \
 222 do {                                                                    \
 223     IOTimeStampStart(IODBG_WORKLOOP(IOWL_CLIENT),                       \
 224                      (unsigned int) this, (unsigned int) event);        \
 225 } while(0)
 226
 227 #define IOTimeClientE()                                                 \
 228 do {                                                                    \
 229     IOTimeStampEnd(IODBG_WORKLOOP(IOWL_CLIENT),                         \
 230                    (unsigned int) this, (unsigned int) event);          \
 231 } while(0)
 232
 233 #define IOTimeWorkS()                                                   \
 234 do {                                                                    \
 235     IOTimeStampStart(IODBG_WORKLOOP(IOWL_WORK), (unsigned int) this);   \
 236 } while(0)
 237
 238 #define IOTimeWorkE()                                                   \
 239 do {                                                                    \
 240     IOTimeStampEnd(IODBG_WORKLOOP(IOWL_WORK),(unsigned int) this);      \
 241 } while(0)
 242
 243 #else /* !KDEBUG */
 244
 245 #define IOTimeClientS()
 246 #define IOTimeClientE()
 247 #define IOTimeWorkS()
 248 #define IOTimeWorkE()
 249
 250 #endif /* KDEBUG */
 251
 252 void IOWorkLoop::threadMainContinuation()
 253 {
 254   IOWorkLoop* self;
 255   self = (IOWorkLoop *) thread_get_cont_arg();
 256
 257   self->threadMain();
 258 }
 259
 260 void IOWorkLoop::threadMain()
 261 {
 262     CLRP(&fFlags, kLoopRestart);
 263
 264     for (;;) {
 265         bool more;
 266         IOInterruptState is;
 267
 268     IOTimeWorkS();
 269
 270         closeGate();
 271         if (ISSETP(&fFlags, kLoopTerminate))
 272             goto exitThread;
 273
 274         do {
 275             workToDo = more = false;
 276             for (IOEventSource *event = eventChain; event; event = event->getNext()) {
 277
 278             IOTimeClientS();
 279                 more |= event->checkForWork();
 280             IOTimeClientE();
 281
 282                 if (ISSETP(&fFlags, kLoopTerminate))
 283                     goto exitThread;
 284                 else if (fFlags & kLoopRestart) {
 285                     CLRP(&fFlags, kLoopRestart);
 286                     continue;
 287                 }
 288             }
 289         } while (more);
 290
 291     IOTimeWorkE();
 292
 293         openGate();
 294
 295         is = IOSimpleLockLockDisableInterrupt(workToDoLock);
 296         if ( !ISSETP(&fFlags, kLoopTerminate) && !workToDo) {
 297             assert_wait((void *) &workToDo, false);
 298             IOSimpleLockUnlockEnableInterrupt(workToDoLock, is);
 299
 300 #if defined (__i386__)
 301             thread_block(0);
 302             continue;
 303 #else
 304             thread_set_cont_arg((int) this);
 305             thread_block(&threadMainContinuation);
 306 #endif
 307             /* NOTREACHED */
 308         }
 309
 310         // At this point we either have work to do or we need
 311         // to commit suicide.  But no matter
 312         // Clear the simple lock and retore the interrupt state
 313         IOSimpleLockUnlockEnableInterrupt(workToDoLock, is);
 314         if (workToDo)
 315             continue;
 316         else
 317             break;
 318     }
 319
 320 exitThread:
 321     workThread = 0;     // Say we don't have a loop and free ourselves
 322     free();
 323     IOExitThread(0);
 324 }
 325
 326 IOThread IOWorkLoop::getThread() const
 327 {
 328     return workThread;
 329 }
 330
 331 bool IOWorkLoop::onThread() const
 332 {
 333     return (IOThreadSelf() == workThread);
 334 }
 335
 336 bool IOWorkLoop::inGate() const
 337 {
 338     return IORecursiveLockHaveLock(gateLock);
 339 }
 340
 341 // Internal APIs used by event sources to control the thread
 342 void IOWorkLoop::signalWorkAvailable()
 343 {
 344     if (workToDoLock) {
 345         IOInterruptState is = IOSimpleLockLockDisableInterrupt(workToDoLock);
 346         workToDo = true;
 347         thread_wakeup_one((void *) &workToDo);
 348         IOSimpleLockUnlockEnableInterrupt(workToDoLock, is);
 349     }
 350 }
 351
 352 void IOWorkLoop::openGate()
 353 {
 354     IORecursiveLockUnlock(gateLock);
 355 }
 356
 357 void IOWorkLoop::closeGate()
 358 {
 359     IORecursiveLockLock(gateLock);
 360 }
 361
 362 bool IOWorkLoop::tryCloseGate()
 363 {
 364     return IORecursiveLockTryLock(gateLock) != 0;
 365 }
 366
 367 int IOWorkLoop::sleepGate(void *event, UInt32 interuptibleType)
 368 {
 369     return IORecursiveLockSleep(gateLock, event, interuptibleType);
 370 }
 371
 372 void IOWorkLoop::wakeupGate(void *event, bool oneThread)
 373 {
 374     IORecursiveLockWakeup(gateLock, event, oneThread);
 375 }
 376
 377 IOReturn IOWorkLoop::_maintRequest(void *inC, void *inD, void *, void *)
 378 {
 379     maintCommandEnum command = (maintCommandEnum) (vm_address_t) inC;
 380     IOEventSource *inEvent = (IOEventSource *) inD;
 381     IOReturn res = kIOReturnSuccess;
 382
 383     switch (command)
 384     {
 385     case mAddEvent:
 386         SETP(&fFlags, kLoopRestart);
 387         inEvent->retain();
 388         inEvent->setWorkLoop(this);
 389         inEvent->setNext(0);
 390
 391         if (!eventChain)
 392             eventChain = inEvent;
 393         else {
 394             IOEventSource *event, *next;
 395
 396             for (event = eventChain; (next = event->getNext()); event = next)
 397                 ;
 398             event->setNext(inEvent);
 399         }
 400         break;
 401
 402     case mRemoveEvent:
 403         if (eventChain == inEvent)
 404             eventChain = inEvent->getNext();
 405         else {
 406             IOEventSource *event, *next;
 407
 408             event = eventChain;
 409             while ((next = event->getNext()) && next != inEvent)
 410                 event = next;
 411
 412             if (!next) {
 413                 res = kIOReturnBadArgument;
 414                 break;
 415             }
 416             event->setNext(inEvent->getNext());
 417         }
 418
 419         inEvent->setWorkLoop(0);
 420         inEvent->setNext(0);
 421         inEvent->release();
 422         SETP(&fFlags, kLoopRestart);
 423         break;
 424
 425     default:
 426         return kIOReturnUnsupported;
 427     }
 428
 429     return res;
 430 }