iokit/Kernel/IOWorkLoop.cpp

   1 /*
   2  * Copyright (c) 1998-2007 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,
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  23  * Please see the License for the specific language governing rights and
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  26  * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
  27  */
  28 /*
  29 Copyright (c) 1998 Apple Computer, Inc.  All rights reserved.
  30
  31 HISTORY
  32     1998-7-13   Godfrey van der Linden(gvdl)
  33         Created.
  34 */
  35 #include <IOKit/IOWorkLoop.h>
  36 #include <IOKit/IOEventSource.h>
  37 #include <IOKit/IOInterruptEventSource.h>
  38 #include <IOKit/IOCommandGate.h>
  39 #include <IOKit/IOTimeStamp.h>
  40 #include <libkern/OSDebug.h>
  41
  42 #define super OSObject
  43
  44 OSDefineMetaClassAndStructors(IOWorkLoop, OSObject);
  45
  46 // Block of unused functions intended for future use
  47 OSMetaClassDefineReservedUsed(IOWorkLoop, 0);
  48 OSMetaClassDefineReservedUsed(IOWorkLoop, 1);
  49
  50 OSMetaClassDefineReservedUnused(IOWorkLoop, 2);
  51 OSMetaClassDefineReservedUnused(IOWorkLoop, 3);
  52 OSMetaClassDefineReservedUnused(IOWorkLoop, 4);
  53 OSMetaClassDefineReservedUnused(IOWorkLoop, 5);
  54 OSMetaClassDefineReservedUnused(IOWorkLoop, 6);
  55 OSMetaClassDefineReservedUnused(IOWorkLoop, 7);
  56
  57 enum IOWorkLoopState { kLoopRestart = 0x1, kLoopTerminate = 0x2 };
  58 #ifdef __ppc__
  59 static inline void SETP(void *addr, unsigned int flag)
  60     { unsigned int *num = (unsigned int *) addr; *num |= flag; }
  61 static inline void CLRP(void *addr, unsigned int flag)
  62     { unsigned int *num = (unsigned int *) addr; *num &= ~flag; }
  63 static inline bool ISSETP(void *addr, unsigned int flag)
  64     { unsigned int *num = (unsigned int *) addr; return (*num & flag) != 0; }
  65 #else
  66 static inline void SETP(void *addr, unsigned int flag)
  67     { unsigned char *num = (unsigned char *) addr; *num |= flag; }
  68 static inline void CLRP(void *addr, unsigned int flag)
  69     { unsigned char *num = (unsigned char *) addr; *num &= ~flag; }
  70 static inline bool ISSETP(void *addr, unsigned int flag)
  71     { unsigned char *num = (unsigned char *) addr; return (*num & flag) != 0; }
  72 #endif
  73
  74 #define fFlags loopRestart
  75
  76 bool IOWorkLoop::init()
  77 {
  78     // The super init and gateLock allocation MUST be done first
  79     if ( !super::init() )
  80         return false;
  81
  82     if ( gateLock == NULL ) {
  83         if ( !( gateLock = IORecursiveLockAlloc()) )
  84             return false;
  85     }
  86
  87     if ( workToDoLock == NULL ) {
  88         if ( !(workToDoLock = IOSimpleLockAlloc()) )
  89             return false;
  90         IOSimpleLockInit(workToDoLock);
  91         workToDo = false;
  92     }
  93
  94     if ( controlG == NULL ) {
  95         controlG = IOCommandGate::commandGate(
  96             this,
  97             OSMemberFunctionCast(
  98                 IOCommandGate::Action,
  99                 this,
 100                 &IOWorkLoop::_maintRequest));
 101
 102         if ( !controlG )
 103             return false;
 104         // Point the controlGate at the workLoop.  Usually addEventSource
 105         // does this automatically.  The problem is in this case addEventSource
 106         // uses the control gate and it has to be bootstrapped.
 107         controlG->setWorkLoop(this);
 108         if (addEventSource(controlG) != kIOReturnSuccess)
 109             return false;
 110     }
 111
 112     if ( workThread == NULL ) {
 113         IOThreadFunc cptr = OSMemberFunctionCast(
 114             IOThreadFunc,
 115             this,
 116             &IOWorkLoop::threadMain);
 117         workThread = IOCreateThread(cptr, this);
 118         if (!workThread)
 119             return false;
 120     }
 121
 122     return true;
 123 }
 124
 125 IOWorkLoop *
 126 IOWorkLoop::workLoop()
 127 {
 128     return IOWorkLoop::workLoopWithOptions(0);
 129 }
 130
 131 IOWorkLoop *
 132 IOWorkLoop::workLoopWithOptions(IOOptionBits options)
 133 {
 134     IOWorkLoop *me = new IOWorkLoop;
 135
 136     if (me && options) {
 137         me->reserved = IONew(ExpansionData, 1);
 138         if (!me->reserved) {
 139             me->release();
 140             return 0;
 141         }
 142         me->reserved->options = options;
 143     }
 144
 145     if (me && !me->init()) {
 146         me->release();
 147         return 0;
 148     }
 149
 150     return me;
 151 }
 152
 153 // Free is called twice:
 154 // First when the atomic retainCount transitions from 1 -> 0
 155 // Secondly when the work loop itself is commiting hari kari
 156 // Hence the each leg of the free must be single threaded.
 157 void IOWorkLoop::free()
 158 {
 159     if (workThread) {
 160         IOInterruptState is;
 161
 162         // If we are here then we must be trying to shut down this work loop
 163         // in this case disable all of the event source, mark the loop
 164         // as terminating and wakeup the work thread itself and return
 165         // Note: we hold the gate across the entire operation mainly for the
 166         // benefit of our event sources so we can disable them cleanly.
 167         closeGate();
 168
 169         disableAllEventSources();
 170
 171         is = IOSimpleLockLockDisableInterrupt(workToDoLock);
 172         SETP(&fFlags, kLoopTerminate);
 173         thread_wakeup_one((void *) &workToDo);
 174         IOSimpleLockUnlockEnableInterrupt(workToDoLock, is);
 175
 176         openGate();
 177     }
 178     else /* !workThread */ {
 179         IOEventSource *event, *next;
 180
 181         for (event = eventChain; event; event = next) {
 182             next = event->getNext();
 183             event->setWorkLoop(0);
 184             event->setNext(0);
 185             event->release();
 186         }
 187         eventChain = 0;
 188
 189         // Either we have a partial initialization to clean up
 190         // or the workThread itself is performing hari-kari.
 191         // Either way clean up all of our resources and return.
 192
 193         if (controlG) {
 194             controlG->release();
 195             controlG = 0;
 196         }
 197
 198         if (workToDoLock) {
 199             IOSimpleLockFree(workToDoLock);
 200             workToDoLock = 0;
 201         }
 202
 203         if (gateLock) {
 204             IORecursiveLockFree(gateLock);
 205             gateLock = 0;
 206         }
 207         if (reserved) {
 208             IODelete(reserved, ExpansionData, 1);
 209             reserved = 0;
 210         }
 211
 212         super::free();
 213     }
 214 }
 215
 216 IOReturn IOWorkLoop::addEventSource(IOEventSource *newEvent)
 217 {
 218     return controlG->runCommand((void *) mAddEvent, (void *) newEvent);
 219 }
 220
 221 IOReturn IOWorkLoop::removeEventSource(IOEventSource *toRemove)
 222 {
 223     return controlG->runCommand((void *) mRemoveEvent, (void *) toRemove);
 224 }
 225
 226 void IOWorkLoop::enableAllEventSources() const
 227 {
 228     IOEventSource *event;
 229
 230     for (event = eventChain; event; event = event->getNext())
 231         event->enable();
 232 }
 233
 234 void IOWorkLoop::disableAllEventSources() const
 235 {
 236     IOEventSource *event;
 237
 238     for (event = eventChain; event; event = event->getNext())
 239         if (event != controlG)  // Don't disable the control gate
 240             event->disable();
 241 }
 242
 243 void IOWorkLoop::enableAllInterrupts() const
 244 {
 245     IOEventSource *event;
 246
 247     for (event = eventChain; event; event = event->getNext())
 248         if (OSDynamicCast(IOInterruptEventSource, event))
 249             event->enable();
 250 }
 251
 252 void IOWorkLoop::disableAllInterrupts() const
 253 {
 254     IOEventSource *event;
 255
 256     for (event = eventChain; event; event = event->getNext())
 257         if (OSDynamicCast(IOInterruptEventSource, event))
 258             event->disable();
 259 }
 260
 261 #if KDEBUG
 262 #define IOTimeClientS()                                                 \
 263 do {                                                                    \
 264     IOTimeStampStart(IODBG_WORKLOOP(IOWL_CLIENT),                       \
 265                      (unsigned int) this, (unsigned int) event);        \
 266 } while(0)
 267
 268 #define IOTimeClientE()                                                 \
 269 do {                                                                    \
 270     IOTimeStampEnd(IODBG_WORKLOOP(IOWL_CLIENT),                         \
 271                    (unsigned int) this, (unsigned int) event);          \
 272 } while(0)
 273
 274 #define IOTimeWorkS()                                                   \
 275 do {                                                                    \
 276     IOTimeStampStart(IODBG_WORKLOOP(IOWL_WORK), (unsigned int) this);   \
 277 } while(0)
 278
 279 #define IOTimeWorkE()                                                   \
 280 do {                                                                    \
 281     IOTimeStampEnd(IODBG_WORKLOOP(IOWL_WORK),(unsigned int) this);      \
 282 } while(0)
 283
 284 #else /* !KDEBUG */
 285
 286 #define IOTimeClientS()
 287 #define IOTimeClientE()
 288 #define IOTimeWorkS()
 289 #define IOTimeWorkE()
 290
 291 #endif /* KDEBUG */
 292
 293 /* virtual */ bool IOWorkLoop::runEventSources()
 294 {
 295     bool res = false;
 296     closeGate();
 297     if (ISSETP(&fFlags, kLoopTerminate))
 298         goto abort;
 299
 300     IOTimeWorkS();
 301     bool more;
 302     do {
 303         CLRP(&fFlags, kLoopRestart);
 304         workToDo = more = false;
 305         for (IOEventSource *evnt = eventChain; evnt; evnt = evnt->getNext()) {
 306
 307             IOTimeClientS();
 308             more |= evnt->checkForWork();
 309             IOTimeClientE();
 310
 311             if (ISSETP(&fFlags, kLoopTerminate))
 312                 goto abort;
 313             else if (fFlags & kLoopRestart) {
 314                 more = true;
 315                 break;
 316             }
 317         }
 318     } while (more);
 319
 320     res = true;
 321     IOTimeWorkE();
 322
 323 abort:
 324     openGate();
 325     return res;
 326 }
 327
 328 /* virtual */ void IOWorkLoop::threadMain()
 329 {
 330 restartThread:
 331     do {
 332         if ( !runEventSources() )
 333             goto exitThread;
 334
 335         IOInterruptState is = IOSimpleLockLockDisableInterrupt(workToDoLock);
 336         if ( !ISSETP(&fFlags, kLoopTerminate) && !workToDo) {
 337             assert_wait((void *) &workToDo, false);
 338             IOSimpleLockUnlockEnableInterrupt(workToDoLock, is);
 339             thread_continue_t cptr = NULL;
 340             if (!reserved || !(kPreciousStack & reserved->options))
 341                 cptr = OSMemberFunctionCast(
 342                         thread_continue_t, this, &IOWorkLoop::threadMain);
 343             thread_block_parameter(cptr, this);
 344             goto restartThread;
 345             /* NOTREACHED */
 346         }
 347
 348         // At this point we either have work to do or we need
 349         // to commit suicide.  But no matter
 350         // Clear the simple lock and retore the interrupt state
 351         IOSimpleLockUnlockEnableInterrupt(workToDoLock, is);
 352     } while(workToDo);
 353
 354 exitThread:
 355     workThread = 0;     // Say we don't have a loop and free ourselves
 356     free();
 357     IOExitThread();
 358 }
 359
 360 IOThread IOWorkLoop::getThread() const
 361 {
 362     return workThread;
 363 }
 364
 365 bool IOWorkLoop::onThread() const
 366 {
 367     return (IOThreadSelf() == workThread);
 368 }
 369
 370 bool IOWorkLoop::inGate() const
 371 {
 372     return IORecursiveLockHaveLock(gateLock);
 373 }
 374
 375 // Internal APIs used by event sources to control the thread
 376 void IOWorkLoop::signalWorkAvailable()
 377 {
 378     if (workToDoLock) {
 379         IOInterruptState is = IOSimpleLockLockDisableInterrupt(workToDoLock);
 380         workToDo = true;
 381         thread_wakeup_one((void *) &workToDo);
 382         IOSimpleLockUnlockEnableInterrupt(workToDoLock, is);
 383     }
 384 }
 385
 386 void IOWorkLoop::openGate()
 387 {
 388     IORecursiveLockUnlock(gateLock);
 389 }
 390
 391 void IOWorkLoop::closeGate()
 392 {
 393     IORecursiveLockLock(gateLock);
 394 }
 395
 396 bool IOWorkLoop::tryCloseGate()
 397 {
 398     return IORecursiveLockTryLock(gateLock) != 0;
 399 }
 400
 401 int IOWorkLoop::sleepGate(void *event, UInt32 interuptibleType)
 402 {
 403     return IORecursiveLockSleep(gateLock, event, interuptibleType);
 404 }
 405
 406 void IOWorkLoop::wakeupGate(void *event, bool oneThread)
 407 {
 408     IORecursiveLockWakeup(gateLock, event, oneThread);
 409 }
 410
 411 IOReturn IOWorkLoop::runAction(Action inAction, OSObject *target,
 412                                   void *arg0, void *arg1,
 413                                   void *arg2, void *arg3)
 414 {
 415     IOReturn res;
 416
 417     // closeGate is recursive so don't worry if we already hold the lock.
 418     closeGate();
 419     res = (*inAction)(target, arg0, arg1, arg2, arg3);
 420     openGate();
 421
 422     return res;
 423 }
 424
 425 IOReturn IOWorkLoop::_maintRequest(void *inC, void *inD, void *, void *)
 426 {
 427     maintCommandEnum command = (maintCommandEnum) (vm_address_t) inC;
 428     IOEventSource *inEvent = (IOEventSource *) inD;
 429     IOReturn res = kIOReturnSuccess;
 430
 431     switch (command)
 432     {
 433     case mAddEvent:
 434         if (!inEvent->getWorkLoop()) {
 435             SETP(&fFlags, kLoopRestart);
 436
 437             inEvent->retain();
 438             inEvent->setWorkLoop(this);
 439             inEvent->setNext(0);
 440
 441             if (!eventChain)
 442                 eventChain = inEvent;
 443             else {
 444                 IOEventSource *event, *next;
 445
 446                 for (event = eventChain; (next = event->getNext()); event = next)
 447                     ;
 448                 event->setNext(inEvent);
 449             }
 450         }
 451         break;
 452
 453     case mRemoveEvent:
 454         if (inEvent->getWorkLoop()) {
 455             if (eventChain == inEvent)
 456                 eventChain = inEvent->getNext();
 457             else {
 458                 IOEventSource *event, *next;
 459
 460                 event = eventChain;
 461                 while ((next = event->getNext()) && next != inEvent)
 462                     event = next;
 463
 464                 if (!next) {
 465                     res = kIOReturnBadArgument;
 466                     break;
 467                 }
 468                 event->setNext(inEvent->getNext());
 469             }
 470
 471             inEvent->setWorkLoop(0);
 472             inEvent->setNext(0);
 473             inEvent->release();
 474             SETP(&fFlags, kLoopRestart);
 475         }
 476         break;
 477
 478     default:
 479         return kIOReturnUnsupported;
 480     }
 481
 482     return res;
 483 }