iokit/Kernel/IOWorkLoop.cpp

   1 /*
   2  * Copyright (c) 1998-2010 Apple 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
  29 #include <pexpert/pexpert.h>
  30 #include <IOKit/IOWorkLoop.h>
  31 #include <IOKit/IOEventSource.h>
  32 #include <IOKit/IOInterruptEventSource.h>
  33 #include <IOKit/IOCommandGate.h>
  34 #include <IOKit/IOCommandPool.h>
  35 #include <IOKit/IOTimeStamp.h>
  36 #include <IOKit/IOKitDebug.h>
  37 #include <libkern/OSDebug.h>
  38 #include <kern/thread.h>
  39
  40 #define super OSObject
  41
  42 OSDefineMetaClassAndStructors(IOWorkLoop, OSObject);
  43
  44 // Block of unused functions intended for future use
  45 #if __LP64__
  46 OSMetaClassDefineReservedUnused(IOWorkLoop, 0);
  47 OSMetaClassDefineReservedUnused(IOWorkLoop, 1);
  48 OSMetaClassDefineReservedUnused(IOWorkLoop, 2);
  49 #else
  50 OSMetaClassDefineReservedUsed(IOWorkLoop, 0);
  51 OSMetaClassDefineReservedUsed(IOWorkLoop, 1);
  52 OSMetaClassDefineReservedUsed(IOWorkLoop, 2);
  53 #endif
  54 OSMetaClassDefineReservedUnused(IOWorkLoop, 3);
  55 OSMetaClassDefineReservedUnused(IOWorkLoop, 4);
  56 OSMetaClassDefineReservedUnused(IOWorkLoop, 5);
  57 OSMetaClassDefineReservedUnused(IOWorkLoop, 6);
  58 OSMetaClassDefineReservedUnused(IOWorkLoop, 7);
  59
  60 enum IOWorkLoopState { kLoopRestart = 0x1, kLoopTerminate = 0x2 };
  61 static inline void
  62 SETP(void *addr, unsigned int flag)
  63 {
  64         unsigned char *num = (unsigned char *) addr; *num |= flag;
  65 }
  66 static inline void
  67 CLRP(void *addr, unsigned int flag)
  68 {
  69         unsigned char *num = (unsigned char *) addr; *num &= ~flag;
  70 }
  71 static inline bool
  72 ISSETP(void *addr, unsigned int flag)
  73 {
  74         unsigned char *num = (unsigned char *) addr; return (*num & flag) != 0;
  75 }
  76
  77 #define fFlags loopRestart
  78
  79 #define passiveEventChain       reserved->passiveEventChain
  80
  81 #if IOKITSTATS
  82
  83 #define IOStatisticsRegisterCounter() \
  84 do { \
  85         reserved->counter = IOStatistics::registerWorkLoop(this); \
  86 } while(0)
  87
  88 #define IOStatisticsUnregisterCounter() \
  89 do { \
  90         if (reserved) \
  91                 IOStatistics::unregisterWorkLoop(reserved->counter); \
  92 } while(0)
  93
  94 #define IOStatisticsOpenGate() \
  95 do { \
  96         IOStatistics::countWorkLoopOpenGate(reserved->counter); \
  97         if (reserved->lockInterval) lockTime();                 \
  98 } while(0)
  99 #define IOStatisticsCloseGate() \
 100 do { \
 101         IOStatistics::countWorkLoopCloseGate(reserved->counter);                    \
 102         if (reserved->lockInterval) reserved->lockTime = mach_absolute_time();      \
 103 } while(0)
 104
 105 #define IOStatisticsAttachEventSource() \
 106 do { \
 107         IOStatistics::attachWorkLoopEventSource(reserved->counter, inEvent->reserved->counter); \
 108 } while(0)
 109
 110 #define IOStatisticsDetachEventSource() \
 111 do { \
 112         IOStatistics::detachWorkLoopEventSource(reserved->counter, inEvent->reserved->counter); \
 113 } while(0)
 114
 115 #else
 116
 117 #define IOStatisticsRegisterCounter()
 118 #define IOStatisticsUnregisterCounter()
 119 #define IOStatisticsOpenGate()
 120 #define IOStatisticsCloseGate()
 121 #define IOStatisticsAttachEventSource()
 122 #define IOStatisticsDetachEventSource()
 123
 124 #endif /* IOKITSTATS */
 125
 126 bool
 127 IOWorkLoop::init()
 128 {
 129         // The super init and gateLock allocation MUST be done first.
 130         if (!super::init()) {
 131                 return false;
 132         }
 133
 134         // Allocate our ExpansionData if it hasn't been allocated already.
 135         if (!reserved) {
 136                 reserved = IONew(ExpansionData, 1);
 137                 if (!reserved) {
 138                         return false;
 139                 }
 140
 141                 bzero(reserved, sizeof(ExpansionData));
 142         }
 143
 144         if (gateLock == NULL) {
 145                 if (!(gateLock = IORecursiveLockAlloc())) {
 146                         return false;
 147                 }
 148         }
 149
 150         if (workToDoLock == NULL) {
 151                 if (!(workToDoLock = IOSimpleLockAlloc())) {
 152                         return false;
 153                 }
 154                 IOSimpleLockInit(workToDoLock);
 155                 workToDo = false;
 156         }
 157
 158         IOStatisticsRegisterCounter();
 159
 160         if (controlG == NULL) {
 161                 controlG = IOCommandGate::commandGate(
 162                         this,
 163                         OSMemberFunctionCast(
 164                                 IOCommandGate::Action,
 165                                 this,
 166                                 &IOWorkLoop::_maintRequest));
 167
 168                 if (!controlG) {
 169                         return false;
 170                 }
 171                 // Point the controlGate at the workLoop.  Usually addEventSource
 172                 // does this automatically.  The problem is in this case addEventSource
 173                 // uses the control gate and it has to be bootstrapped.
 174                 controlG->setWorkLoop(this);
 175                 if (addEventSource(controlG) != kIOReturnSuccess) {
 176                         return false;
 177                 }
 178         }
 179
 180         if (workThread == NULL) {
 181                 thread_continue_t cptr = OSMemberFunctionCast(
 182                         thread_continue_t,
 183                         this,
 184                         &IOWorkLoop::threadMain);
 185                 if (KERN_SUCCESS != kernel_thread_start(cptr, this, &workThread)) {
 186                         return false;
 187                 }
 188         }
 189
 190         (void) thread_set_tag(workThread, THREAD_TAG_IOWORKLOOP);
 191         return true;
 192 }
 193
 194 IOWorkLoop *
 195 IOWorkLoop::workLoop()
 196 {
 197         return IOWorkLoop::workLoopWithOptions(0);
 198 }
 199
 200 IOWorkLoop *
 201 IOWorkLoop::workLoopWithOptions(IOOptionBits options)
 202 {
 203         IOWorkLoop *me = new IOWorkLoop;
 204
 205         if (me && options) {
 206                 me->reserved = IONew(ExpansionData, 1);
 207                 if (!me->reserved) {
 208                         me->release();
 209                         return 0;
 210                 }
 211                 bzero(me->reserved, sizeof(ExpansionData));
 212                 me->reserved->options = options;
 213         }
 214
 215         if (me && !me->init()) {
 216                 me->release();
 217                 return 0;
 218         }
 219
 220         return me;
 221 }
 222
 223 // Free is called twice:
 224 // First when the atomic retainCount transitions from 1 -> 0
 225 // Secondly when the work loop itself is commiting hari kari
 226 // Hence the each leg of the free must be single threaded.
 227 void
 228 IOWorkLoop::free()
 229 {
 230         if (workThread) {
 231                 IOInterruptState is;
 232
 233                 // If we are here then we must be trying to shut down this work loop
 234                 // in this case disable all of the event source, mark the loop
 235                 // as terminating and wakeup the work thread itself and return
 236                 // Note: we hold the gate across the entire operation mainly for the
 237                 // benefit of our event sources so we can disable them cleanly.
 238                 closeGate();
 239
 240                 disableAllEventSources();
 241
 242                 is = IOSimpleLockLockDisableInterrupt(workToDoLock);
 243                 SETP(&fFlags, kLoopTerminate);
 244                 thread_wakeup_thread((void *) &workToDo, workThread);
 245                 IOSimpleLockUnlockEnableInterrupt(workToDoLock, is);
 246
 247                 openGate();
 248         } else { /* !workThread */
 249                 IOEventSource *event, *next;
 250
 251                 for (event = eventChain; event; event = next) {
 252                         next = event->getNext();
 253                         event->setWorkLoop(0);
 254                         event->setNext(0);
 255                         event->release();
 256                 }
 257                 eventChain = 0;
 258
 259                 for (event = passiveEventChain; event; event = next) {
 260                         next = event->getNext();
 261                         event->setWorkLoop(0);
 262                         event->setNext(0);
 263                         event->release();
 264                 }
 265                 passiveEventChain = 0;
 266
 267                 // Either we have a partial initialization to clean up
 268                 // or the workThread itself is performing hari-kari.
 269                 // Either way clean up all of our resources and return.
 270
 271                 if (controlG) {
 272                         controlG->workLoop = 0;
 273                         controlG->release();
 274                         controlG = 0;
 275                 }
 276
 277                 if (workToDoLock) {
 278                         IOSimpleLockFree(workToDoLock);
 279                         workToDoLock = 0;
 280                 }
 281
 282                 if (gateLock) {
 283                         IORecursiveLockFree(gateLock);
 284                         gateLock = 0;
 285                 }
 286
 287                 IOStatisticsUnregisterCounter();
 288
 289                 if (reserved) {
 290                         IODelete(reserved, ExpansionData, 1);
 291                         reserved = 0;
 292                 }
 293
 294                 super::free();
 295         }
 296 }
 297
 298 IOReturn
 299 IOWorkLoop::addEventSource(IOEventSource *newEvent)
 300 {
 301         if ((workThread)
 302             && !thread_has_thread_name(workThread)
 303             && (newEvent->owner)
 304             && !OSDynamicCast(IOCommandPool, newEvent->owner)) {
 305                 thread_set_thread_name(workThread, newEvent->owner->getMetaClass()->getClassName());
 306         }
 307
 308         return controlG->runCommand((void *) mAddEvent, (void *) newEvent);
 309 }
 310
 311 IOReturn
 312 IOWorkLoop::removeEventSource(IOEventSource *toRemove)
 313 {
 314         return controlG->runCommand((void *) mRemoveEvent, (void *) toRemove);
 315 }
 316
 317 void
 318 IOWorkLoop::enableAllEventSources() const
 319 {
 320         IOEventSource *event;
 321
 322         for (event = eventChain; event; event = event->getNext()) {
 323                 event->enable();
 324         }
 325
 326         for (event = passiveEventChain; event; event = event->getNext()) {
 327                 event->enable();
 328         }
 329 }
 330
 331 void
 332 IOWorkLoop::disableAllEventSources() const
 333 {
 334         IOEventSource *event;
 335
 336         for (event = eventChain; event; event = event->getNext()) {
 337                 event->disable();
 338         }
 339
 340         /* NOTE: controlG is in passiveEventChain since it's an IOCommandGate */
 341         for (event = passiveEventChain; event; event = event->getNext()) {
 342                 if (event != controlG) { // Don't disable the control gate
 343                         event->disable();
 344                 }
 345         }
 346 }
 347
 348 void
 349 IOWorkLoop::enableAllInterrupts() const
 350 {
 351         IOEventSource *event;
 352
 353         for (event = eventChain; event; event = event->getNext()) {
 354                 if (OSDynamicCast(IOInterruptEventSource, event)) {
 355                         event->enable();
 356                 }
 357         }
 358 }
 359
 360 void
 361 IOWorkLoop::disableAllInterrupts() const
 362 {
 363         IOEventSource *event;
 364
 365         for (event = eventChain; event; event = event->getNext()) {
 366                 if (OSDynamicCast(IOInterruptEventSource, event)) {
 367                         event->disable();
 368                 }
 369         }
 370 }
 371
 372
 373 /* virtual */ bool
 374 IOWorkLoop::runEventSources()
 375 {
 376         bool res = false;
 377         bool traceWL = (gIOKitTrace & kIOTraceWorkLoops) ? true : false;
 378         bool traceES = (gIOKitTrace & kIOTraceEventSources) ? true : false;
 379
 380         closeGate();
 381         if (ISSETP(&fFlags, kLoopTerminate)) {
 382                 goto abort;
 383         }
 384
 385         if (traceWL) {
 386                 IOTimeStampStartConstant(IODBG_WORKLOOP(IOWL_WORK), VM_KERNEL_ADDRHIDE(this));
 387         }
 388
 389         bool more;
 390         do {
 391                 CLRP(&fFlags, kLoopRestart);
 392                 more = false;
 393                 IOInterruptState is = IOSimpleLockLockDisableInterrupt(workToDoLock);
 394                 workToDo = false;
 395                 IOSimpleLockUnlockEnableInterrupt(workToDoLock, is);
 396                 /* NOTE: only loop over event sources in eventChain. Bypass "passive" event sources for performance */
 397                 for (IOEventSource *evnt = eventChain; evnt; evnt = evnt->getNext()) {
 398                         if (traceES) {
 399                                 IOTimeStampStartConstant(IODBG_WORKLOOP(IOWL_CLIENT), VM_KERNEL_ADDRHIDE(this), VM_KERNEL_ADDRHIDE(evnt));
 400                         }
 401
 402                         more |= evnt->checkForWork();
 403
 404                         if (traceES) {
 405                                 IOTimeStampEndConstant(IODBG_WORKLOOP(IOWL_CLIENT), VM_KERNEL_ADDRHIDE(this), VM_KERNEL_ADDRHIDE(evnt));
 406                         }
 407
 408                         if (ISSETP(&fFlags, kLoopTerminate)) {
 409                                 goto abort;
 410                         } else if (fFlags & kLoopRestart) {
 411                                 more = true;
 412                                 break;
 413                         }
 414                 }
 415         } while (more);
 416
 417         res = true;
 418
 419         if (traceWL) {
 420                 IOTimeStampEndConstant(IODBG_WORKLOOP(IOWL_WORK), VM_KERNEL_ADDRHIDE(this));
 421         }
 422
 423 abort:
 424         openGate();
 425         return res;
 426 }
 427
 428 /* virtual */ void
 429 IOWorkLoop::threadMain()
 430 {
 431 restartThread:
 432         do {
 433                 if (!runEventSources()) {
 434                         goto exitThread;
 435                 }
 436
 437                 IOInterruptState is = IOSimpleLockLockDisableInterrupt(workToDoLock);
 438                 if (!ISSETP(&fFlags, kLoopTerminate) && !workToDo) {
 439                         assert_wait((void *) &workToDo, false);
 440                         IOSimpleLockUnlockEnableInterrupt(workToDoLock, is);
 441                         thread_continue_t cptr = NULL;
 442                         if (!reserved || !(kPreciousStack & reserved->options)) {
 443                                 cptr = OSMemberFunctionCast(
 444                                         thread_continue_t, this, &IOWorkLoop::threadMain);
 445                         }
 446                         thread_block_parameter(cptr, this);
 447                         goto restartThread;
 448                         /* NOTREACHED */
 449                 }
 450
 451                 // At this point we either have work to do or we need
 452                 // to commit suicide.  But no matter
 453                 // Clear the simple lock and retore the interrupt state
 454                 IOSimpleLockUnlockEnableInterrupt(workToDoLock, is);
 455         } while (workToDo);
 456
 457 exitThread:
 458         closeGate();
 459         thread_t thread = workThread;
 460         workThread = 0; // Say we don't have a loop and free ourselves
 461         openGate();
 462
 463         free();
 464
 465         thread_deallocate(thread);
 466         (void) thread_terminate(thread);
 467 }
 468
 469 IOThread
 470 IOWorkLoop::getThread() const
 471 {
 472         return workThread;
 473 }
 474
 475 bool
 476 IOWorkLoop::onThread() const
 477 {
 478         return IOThreadSelf() == workThread;
 479 }
 480
 481 bool
 482 IOWorkLoop::inGate() const
 483 {
 484         return IORecursiveLockHaveLock(gateLock);
 485 }
 486
 487 // Internal APIs used by event sources to control the thread
 488 void
 489 IOWorkLoop::signalWorkAvailable()
 490 {
 491         if (workToDoLock) {
 492                 IOInterruptState is = IOSimpleLockLockDisableInterrupt(workToDoLock);
 493                 workToDo = true;
 494                 thread_wakeup_thread((void *) &workToDo, workThread);
 495                 IOSimpleLockUnlockEnableInterrupt(workToDoLock, is);
 496         }
 497 }
 498
 499 void
 500 IOWorkLoop::openGate()
 501 {
 502         IOStatisticsOpenGate();
 503         IORecursiveLockUnlock(gateLock);
 504 }
 505
 506 void
 507 IOWorkLoop::closeGate()
 508 {
 509         IORecursiveLockLock(gateLock);
 510         IOStatisticsCloseGate();
 511 }
 512
 513 bool
 514 IOWorkLoop::tryCloseGate()
 515 {
 516         bool res = (IORecursiveLockTryLock(gateLock) != 0);
 517         if (res) {
 518                 IOStatisticsCloseGate();
 519         }
 520         return res;
 521 }
 522
 523 int
 524 IOWorkLoop::sleepGate(void *event, UInt32 interuptibleType)
 525 {
 526         int res;
 527         IOStatisticsOpenGate();
 528         res = IORecursiveLockSleep(gateLock, event, interuptibleType);
 529         IOStatisticsCloseGate();
 530         return res;
 531 }
 532
 533 int
 534 IOWorkLoop::sleepGate(void *event, AbsoluteTime deadline, UInt32 interuptibleType)
 535 {
 536         int res;
 537         IOStatisticsOpenGate();
 538         res = IORecursiveLockSleepDeadline(gateLock, event, deadline, interuptibleType);
 539         IOStatisticsCloseGate();
 540         return res;
 541 }
 542
 543 void
 544 IOWorkLoop::wakeupGate(void *event, bool oneThread)
 545 {
 546         IORecursiveLockWakeup(gateLock, event, oneThread);
 547 }
 548
 549 static IOReturn
 550 IOWorkLoopActionToBlock(OSObject *owner,
 551     void *arg0, void *arg1,
 552     void *arg2, void *arg3)
 553 {
 554         return ((IOWorkLoop::ActionBlock) arg0)();
 555 }
 556
 557 IOReturn
 558 IOWorkLoop::runActionBlock(ActionBlock action)
 559 {
 560         return runAction(&IOWorkLoopActionToBlock, this, action);
 561 }
 562
 563 IOReturn
 564 IOWorkLoop::runAction(Action inAction, OSObject *target,
 565     void *arg0, void *arg1,
 566     void *arg2, void *arg3)
 567 {
 568         IOReturn res;
 569
 570         // closeGate is recursive so don't worry if we already hold the lock.
 571         closeGate();
 572         res = (*inAction)(target, arg0, arg1, arg2, arg3);
 573         openGate();
 574
 575         return res;
 576 }
 577
 578 IOReturn
 579 IOWorkLoop::_maintRequest(void *inC, void *inD, void *, void *)
 580 {
 581         maintCommandEnum command = (maintCommandEnum) (uintptr_t) inC;
 582         IOEventSource *inEvent = (IOEventSource *) inD;
 583         IOReturn res = kIOReturnSuccess;
 584
 585         switch (command) {
 586         case mAddEvent:
 587                 if (!inEvent->getWorkLoop()) {
 588                         SETP(&fFlags, kLoopRestart);
 589
 590                         inEvent->retain();
 591                         inEvent->setWorkLoop(this);
 592                         inEvent->setNext(0);
 593
 594                         /* Check if this is a passive or active event source being added */
 595                         if (eventSourcePerformsWork(inEvent)) {
 596                                 if (!eventChain) {
 597                                         eventChain = inEvent;
 598                                 } else {
 599                                         IOEventSource *event, *next;
 600
 601                                         for (event = eventChain; (next = event->getNext()); event = next) {
 602                                                 ;
 603                                         }
 604                                         event->setNext(inEvent);
 605                                 }
 606                         } else {
 607                                 if (!passiveEventChain) {
 608                                         passiveEventChain = inEvent;
 609                                 } else {
 610                                         IOEventSource *event, *next;
 611
 612                                         for (event = passiveEventChain; (next = event->getNext()); event = next) {
 613                                                 ;
 614                                         }
 615                                         event->setNext(inEvent);
 616                                 }
 617                         }
 618                         IOStatisticsAttachEventSource();
 619                 }
 620                 break;
 621
 622         case mRemoveEvent:
 623                 if (inEvent->getWorkLoop()) {
 624                         IOStatisticsDetachEventSource();
 625
 626                         if (eventSourcePerformsWork(inEvent)) {
 627                                 if (eventChain == inEvent) {
 628                                         eventChain = inEvent->getNext();
 629                                 } else {
 630                                         IOEventSource *event, *next = 0;
 631
 632                                         event = eventChain;
 633                                         if (event) {
 634                                                 while ((next = event->getNext()) && (next != inEvent)) {
 635                                                         event = next;
 636                                                 }
 637                                         }
 638
 639                                         if (!next) {
 640                                                 res = kIOReturnBadArgument;
 641                                                 break;
 642                                         }
 643                                         event->setNext(inEvent->getNext());
 644                                 }
 645                         } else {
 646                                 if (passiveEventChain == inEvent) {
 647                                         passiveEventChain = inEvent->getNext();
 648                                 } else {
 649                                         IOEventSource *event, *next = 0;
 650
 651                                         event = passiveEventChain;
 652                                         if (event) {
 653                                                 while ((next = event->getNext()) && (next != inEvent)) {
 654                                                         event = next;
 655                                                 }
 656                                         }
 657
 658                                         if (!next) {
 659                                                 res = kIOReturnBadArgument;
 660                                                 break;
 661                                         }
 662                                         event->setNext(inEvent->getNext());
 663                                 }
 664                         }
 665
 666                         inEvent->setWorkLoop(0);
 667                         inEvent->setNext(0);
 668                         inEvent->release();
 669                         SETP(&fFlags, kLoopRestart);
 670                 }
 671                 break;
 672
 673         default:
 674                 return kIOReturnUnsupported;
 675         }
 676
 677         return res;
 678 }
 679
 680 bool
 681 IOWorkLoop::eventSourcePerformsWork(IOEventSource *inEventSource)
 682 {
 683         bool    result = true;
 684
 685         /*
 686          * The idea here is to see if the subclass of IOEventSource has overridden checkForWork().
 687          * The assumption is that if you override checkForWork(), you need to be
 688          * active and not passive.
 689          *
 690          * We picked a known quantity controlG that does not override
 691          * IOEventSource::checkForWork(), namely the IOCommandGate associated with
 692          * the workloop to which this event source is getting attached.
 693          *
 694          * We do a pointer comparison on the offset in the vtable for inNewEvent against
 695          * the offset in the vtable for inReferenceEvent. This works because
 696          * IOCommandGate's slot for checkForWork() has the address of
 697          * IOEventSource::checkForWork() in it.
 698          *
 699          * Think of OSMemberFunctionCast yielding the value at the vtable offset for
 700          * checkForWork() here. We're just testing to see if it's the same or not.
 701          *
 702          */
 703
 704         if (IOEventSource::kPassive & inEventSource->flags) {
 705                 result = false;
 706         } else if (IOEventSource::kActive & inEventSource->flags) {
 707                 result = true;
 708         } else if (controlG) {
 709                 void *  ptr1;
 710                 void *  ptr2;
 711
 712                 ptr1 = OSMemberFunctionCast(void*, inEventSource, &IOEventSource::checkForWork);
 713                 ptr2 = OSMemberFunctionCast(void*, controlG, &IOEventSource::checkForWork);
 714
 715                 if (ptr1 == ptr2) {
 716                         result = false;
 717                 }
 718         }
 719
 720         return result;
 721 }
 722
 723 void
 724 IOWorkLoop::lockTime(void)
 725 {
 726         uint64_t time;
 727         time = mach_absolute_time() - reserved->lockTime;
 728         if (time > reserved->lockInterval) {
 729                 absolutetime_to_nanoseconds(time, &time);
 730                 if (kTimeLockPanics & reserved->options) {
 731                         panic("IOWorkLoop %p lock time %qd us", this, time / 1000ULL);
 732                 } else {
 733                         OSReportWithBacktrace("IOWorkLoop %p lock time %qd us", this, time / 1000ULL);
 734                 }
 735         }
 736 }
 737
 738 void
 739 IOWorkLoop::setMaximumLockTime(uint64_t interval, uint32_t options)
 740 {
 741         IORecursiveLockLock(gateLock);
 742         reserved->lockInterval = interval;
 743         reserved->options = (reserved->options & ~kTimeLockPanics) | (options & kTimeLockPanics);
 744         IORecursiveLockUnlock(gateLock);
 745 }