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 OSMetaClassDefineReservedUsed(IOWorkLoop, 0);
  41
  42 OSMetaClassDefineReservedUnused(IOWorkLoop, 1);
  43 OSMetaClassDefineReservedUnused(IOWorkLoop, 2);
  44 OSMetaClassDefineReservedUnused(IOWorkLoop, 3);
  45 OSMetaClassDefineReservedUnused(IOWorkLoop, 4);
  46 OSMetaClassDefineReservedUnused(IOWorkLoop, 5);
  47 OSMetaClassDefineReservedUnused(IOWorkLoop, 6);
  48 OSMetaClassDefineReservedUnused(IOWorkLoop, 7);
  49
  50 enum IOWorkLoopState { kLoopRestart = 0x1, kLoopTerminate = 0x2 };
  51 static inline void SETP(void *addr, unsigned int flag)
  52     { unsigned int *num = (unsigned int *) addr; *num |= flag; }
  53 static inline void CLRP(void *addr, unsigned int flag)
  54     { unsigned int *num = (unsigned int *) addr; *num &= ~flag; }
  55 static inline bool ISSETP(void *addr, unsigned int flag)
  56     { unsigned int *num = (unsigned int *) addr; return (*num & flag) != 0; }
  57
  58 #define fFlags loopRestart
  59
  60 void IOWorkLoop::launchThreadMain(void *self)
  61 {
  62     thread_set_cont_arg((int) self);
  63     threadMainContinuation();
  64 }
  65
  66 bool IOWorkLoop::init()
  67 {
  68     // The super init and gateLock allocation MUST be done first
  69     if ( !super::init() )
  70         return false;
  71
  72     if ( !(gateLock = IORecursiveLockAlloc()) )
  73         return false;
  74
  75     if ( !(workToDoLock = IOSimpleLockAlloc()) )
  76         return false;
  77
  78     controlG = IOCommandGate::
  79         commandGate(this, (IOCommandGate::Action) &IOWorkLoop::_maintRequest);
  80     if ( !controlG )
  81         return false;
  82
  83     IOSimpleLockInit(workToDoLock);
  84     workToDo = false;
  85
  86     // Point the controlGate at the workLoop.  Usually addEventSource
  87     // does this automatically.  The problem is in this case addEventSource
  88     // uses the control gate and it has to be bootstrapped.
  89     controlG->setWorkLoop(this);
  90     if (addEventSource(controlG) != kIOReturnSuccess)
  91         return false;
  92
  93     workThread = IOCreateThread(launchThreadMain, (void *) this);
  94     if (!workThread)
  95         return false;
  96
  97     return true;
  98 }
  99
 100 IOWorkLoop *
 101 IOWorkLoop::workLoop()
 102 {
 103     IOWorkLoop *me = new IOWorkLoop;
 104
 105     if (me && !me->init()) {
 106         me->release();
 107         return 0;
 108     }
 109
 110     return me;
 111 }
 112
 113 // Free is called twice:
 114 // First when the atomic retainCount transitions from 1 -> 0
 115 // Secondly when the work loop itself is commiting hari kari
 116 // Hence the each leg of the free must be single threaded.
 117 void IOWorkLoop::free()
 118 {
 119     if (workThread) {
 120         IOInterruptState is;
 121
 122         // If we are here then we must be trying to shut down this work loop
 123         // in this case disable all of the event source, mark the loop for
 124         // as terminating and wakeup the work thread itself and return
 125         // Note: we hold the gate across the entire operation mainly for the
 126         // benefit of our event sources so we can disable them cleanly.
 127         closeGate();
 128
 129         disableAllEventSources();
 130
 131         is = IOSimpleLockLockDisableInterrupt(workToDoLock);
 132         SETP(&fFlags, kLoopTerminate);
 133         thread_wakeup_one((void *) &workToDo);
 134         IOSimpleLockUnlockEnableInterrupt(workToDoLock, is);
 135
 136         openGate();
 137     }
 138     else /* !workThread */ {
 139         IOEventSource *event, *next;
 140
 141         for (event = eventChain; event; event = next) {
 142             next = event->getNext();
 143             event->setWorkLoop(0);
 144             event->setNext(0);
 145             event->release();
 146         }
 147         eventChain = 0;
 148
 149         // Either we have a partial initialisation to clean up
 150         // or we the workThread itself is performing hari-kari.
 151         // either way clean up all of our resources and return.
 152
 153         if (controlG) {
 154             controlG->release();
 155             controlG = 0;
 156         }
 157
 158         if (workToDoLock) {
 159             IOSimpleLockFree(workToDoLock);
 160             workToDoLock = 0;
 161         }
 162
 163         if (gateLock) {
 164             IORecursiveLockFree(gateLock);
 165             gateLock = 0;
 166         }
 167
 168         super::free();
 169     }
 170 }
 171
 172 IOReturn IOWorkLoop::addEventSource(IOEventSource *newEvent)
 173 {
 174     return controlG->runCommand((void *) mAddEvent, (void *) newEvent);
 175 }
 176
 177 IOReturn IOWorkLoop::removeEventSource(IOEventSource *toRemove)
 178 {
 179     return controlG->runCommand((void *) mRemoveEvent, (void *) toRemove);
 180 }
 181
 182 void IOWorkLoop::enableAllEventSources() const
 183 {
 184     IOEventSource *event;
 185
 186     for (event = eventChain; event; event = event->getNext())
 187         event->enable();
 188 }
 189
 190 void IOWorkLoop::disableAllEventSources() const
 191 {
 192     IOEventSource *event;
 193
 194     for (event = eventChain; event; event = event->getNext())
 195         if (event != controlG)  // Don't disable the control gate
 196             event->disable();
 197 }
 198
 199 void IOWorkLoop::enableAllInterrupts() const
 200 {
 201     IOEventSource *event;
 202
 203     for (event = eventChain; event; event = event->getNext())
 204         if (OSDynamicCast(IOInterruptEventSource, event))
 205             event->enable();
 206 }
 207
 208 void IOWorkLoop::disableAllInterrupts() const
 209 {
 210     IOEventSource *event;
 211
 212     for (event = eventChain; event; event = event->getNext())
 213         if (OSDynamicCast(IOInterruptEventSource, event))
 214             event->disable();
 215 }
 216
 217 #if KDEBUG
 218 #define IOTimeClientS()                                                 \
 219 do {                                                                    \
 220     IOTimeStampStart(IODBG_WORKLOOP(IOWL_CLIENT),                       \
 221                      (unsigned int) this, (unsigned int) event);        \
 222 } while(0)
 223
 224 #define IOTimeClientE()                                                 \
 225 do {                                                                    \
 226     IOTimeStampEnd(IODBG_WORKLOOP(IOWL_CLIENT),                         \
 227                    (unsigned int) this, (unsigned int) event);          \
 228 } while(0)
 229
 230 #define IOTimeWorkS()                                                   \
 231 do {                                                                    \
 232     IOTimeStampStart(IODBG_WORKLOOP(IOWL_WORK), (unsigned int) this);   \
 233 } while(0)
 234
 235 #define IOTimeWorkE()                                                   \
 236 do {                                                                    \
 237     IOTimeStampEnd(IODBG_WORKLOOP(IOWL_WORK),(unsigned int) this);      \
 238 } while(0)
 239
 240 #else /* !KDEBUG */
 241
 242 #define IOTimeClientS()
 243 #define IOTimeClientE()
 244 #define IOTimeWorkS()
 245 #define IOTimeWorkE()
 246
 247 #endif /* KDEBUG */
 248
 249 void IOWorkLoop::threadMainContinuation()
 250 {
 251   IOWorkLoop* self;
 252   self = (IOWorkLoop *) thread_get_cont_arg();
 253
 254   self->threadMain();
 255 }
 256
 257 void IOWorkLoop::threadMain()
 258 {
 259     CLRP(&fFlags, kLoopRestart);
 260
 261     for (;;) {
 262         bool more;
 263         IOInterruptState is;
 264
 265     IOTimeWorkS();
 266
 267         closeGate();
 268         if (ISSETP(&fFlags, kLoopTerminate))
 269             goto exitThread;
 270
 271         do {
 272             workToDo = more = false;
 273             for (IOEventSource *event = eventChain; event; event = event->getNext()) {
 274
 275             IOTimeClientS();
 276                 more |= event->checkForWork();
 277             IOTimeClientE();
 278
 279                 if (ISSETP(&fFlags, kLoopTerminate))
 280                     goto exitThread;
 281                 else if (fFlags & kLoopRestart) {
 282                     CLRP(&fFlags, kLoopRestart);
 283                     continue;
 284                 }
 285             }
 286         } while (more);
 287
 288     IOTimeWorkE();
 289
 290         openGate();
 291
 292         is = IOSimpleLockLockDisableInterrupt(workToDoLock);
 293         if ( !ISSETP(&fFlags, kLoopTerminate) && !workToDo) {
 294             assert_wait((void *) &workToDo, false);
 295             IOSimpleLockUnlockEnableInterrupt(workToDoLock, is);
 296
 297             thread_set_cont_arg((int) this);
 298             thread_block(&threadMainContinuation);
 299             /* NOTREACHED */
 300         }
 301
 302         // At this point we either have work to do or we need
 303         // to commit suicide.  But no matter
 304         // Clear the simple lock and retore the interrupt state
 305         IOSimpleLockUnlockEnableInterrupt(workToDoLock, is);
 306         if (workToDo)
 307             continue;
 308         else
 309             break;
 310     }
 311
 312 exitThread:
 313     workThread = 0;     // Say we don't have a loop and free ourselves
 314     free();
 315     IOExitThread();
 316 }
 317
 318 IOThread IOWorkLoop::getThread() const
 319 {
 320     return workThread;
 321 }
 322
 323 bool IOWorkLoop::onThread() const
 324 {
 325     return (IOThreadSelf() == workThread);
 326 }
 327
 328 bool IOWorkLoop::inGate() const
 329 {
 330     return IORecursiveLockHaveLock(gateLock);
 331 }
 332
 333 // Internal APIs used by event sources to control the thread
 334 void IOWorkLoop::signalWorkAvailable()
 335 {
 336     if (workToDoLock) {
 337         IOInterruptState is = IOSimpleLockLockDisableInterrupt(workToDoLock);
 338         workToDo = true;
 339         thread_wakeup_one((void *) &workToDo);
 340         IOSimpleLockUnlockEnableInterrupt(workToDoLock, is);
 341     }
 342 }
 343
 344 void IOWorkLoop::openGate()
 345 {
 346     IORecursiveLockUnlock(gateLock);
 347 }
 348
 349 void IOWorkLoop::closeGate()
 350 {
 351     IORecursiveLockLock(gateLock);
 352 }
 353
 354 bool IOWorkLoop::tryCloseGate()
 355 {
 356     return IORecursiveLockTryLock(gateLock) != 0;
 357 }
 358
 359 int IOWorkLoop::sleepGate(void *event, UInt32 interuptibleType)
 360 {
 361     return IORecursiveLockSleep(gateLock, event, interuptibleType);
 362 }
 363
 364 void IOWorkLoop::wakeupGate(void *event, bool oneThread)
 365 {
 366     IORecursiveLockWakeup(gateLock, event, oneThread);
 367 }
 368
 369 IOReturn IOWorkLoop::runAction(Action inAction, OSObject *target,
 370                                   void *arg0, void *arg1,
 371                                   void *arg2, void *arg3)
 372 {
 373     IOReturn res;
 374
 375     // closeGate is recursive so don't worry if we already hold the lock.
 376     closeGate();
 377     res = (*inAction)(target, arg0, arg1, arg2, arg3);
 378     openGate();
 379
 380     return res;
 381 }
 382
 383 IOReturn IOWorkLoop::_maintRequest(void *inC, void *inD, void *, void *)
 384 {
 385     maintCommandEnum command = (maintCommandEnum) (vm_address_t) inC;
 386     IOEventSource *inEvent = (IOEventSource *) inD;
 387     IOReturn res = kIOReturnSuccess;
 388
 389     switch (command)
 390     {
 391     case mAddEvent:
 392         if (!inEvent->getWorkLoop()) {
 393             SETP(&fFlags, kLoopRestart);
 394
 395             inEvent->retain();
 396             inEvent->setWorkLoop(this);
 397             inEvent->setNext(0);
 398
 399             if (!eventChain)
 400                 eventChain = inEvent;
 401             else {
 402                 IOEventSource *event, *next;
 403
 404                 for (event = eventChain; (next = event->getNext()); event = next)
 405                     ;
 406                 event->setNext(inEvent);
 407             }
 408         }
 409         break;
 410
 411     case mRemoveEvent:
 412         if (inEvent->getWorkLoop()) {
 413             if (eventChain == inEvent)
 414                 eventChain = inEvent->getNext();
 415             else {
 416                 IOEventSource *event, *next;
 417
 418                 event = eventChain;
 419                 while ((next = event->getNext()) && next != inEvent)
 420                     event = next;
 421
 422                 if (!next) {
 423                     res = kIOReturnBadArgument;
 424                     break;
 425                 }
 426                 event->setNext(inEvent->getNext());
 427             }
 428
 429             inEvent->setWorkLoop(0);
 430             inEvent->setNext(0);
 431             inEvent->release();
 432             SETP(&fFlags, kLoopRestart);
 433         }
 434         break;
 435
 436     default:
 437         return kIOReturnUnsupported;
 438     }
 439
 440     return res;
 441 }