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