iokit/Kernel/IOWorkLoop.cpp

   1 /*
   2  * Copyright (c) 1998-2000 Apple Computer, 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,
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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
  41 #define super OSObject
  42
  43 OSDefineMetaClassAndStructors(IOWorkLoop, OSObject);
  44
  45 // Block of unused functions intended for future use
  46 OSMetaClassDefineReservedUsed(IOWorkLoop, 0);
  47 OSMetaClassDefineReservedUsed(IOWorkLoop, 1);
  48
  49 OSMetaClassDefineReservedUnused(IOWorkLoop, 2);
  50 OSMetaClassDefineReservedUnused(IOWorkLoop, 3);
  51 OSMetaClassDefineReservedUnused(IOWorkLoop, 4);
  52 OSMetaClassDefineReservedUnused(IOWorkLoop, 5);
  53 OSMetaClassDefineReservedUnused(IOWorkLoop, 6);
  54 OSMetaClassDefineReservedUnused(IOWorkLoop, 7);
  55
  56 enum IOWorkLoopState { kLoopRestart = 0x1, kLoopTerminate = 0x2 };
  57 static inline void SETP(void *addr, unsigned int flag)
  58     { unsigned int *num = (unsigned int *) addr; *num |= flag; }
  59 static inline void CLRP(void *addr, unsigned int flag)
  60     { unsigned int *num = (unsigned int *) addr; *num &= ~flag; }
  61 static inline bool ISSETP(void *addr, unsigned int flag)
  62     { unsigned int *num = (unsigned int *) addr; return (*num & flag) != 0; }
  63
  64 #define fFlags loopRestart
  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, OSMemberFunctionCast(IOCommandGate::Action,
  80                                         this, &IOWorkLoop::_maintRequest));
  81     if ( !controlG )
  82         return false;
  83
  84     IOSimpleLockInit(workToDoLock);
  85     workToDo = false;
  86
  87     // Point the controlGate at the workLoop.  Usually addEventSource
  88     // does this automatically.  The problem is in this case addEventSource
  89     // uses the control gate and it has to be bootstrapped.
  90     controlG->setWorkLoop(this);
  91     if (addEventSource(controlG) != kIOReturnSuccess)
  92         return false;
  93
  94     IOThreadFunc cptr =
  95         OSMemberFunctionCast(IOThreadFunc, this, &IOWorkLoop::threadMain);
  96     workThread = IOCreateThread(cptr, 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->release();
 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 /* virtual */ bool IOWorkLoop::runEventSources()
 253 {
 254     bool res = false;
 255     closeGate();
 256     if (ISSETP(&fFlags, kLoopTerminate))
 257         goto abort;
 258
 259     IOTimeWorkS();
 260     bool more;
 261     do {
 262         CLRP(&fFlags, kLoopRestart);
 263         workToDo = more = false;
 264         for (IOEventSource *evnt = eventChain; evnt; evnt = evnt->getNext()) {
 265
 266             IOTimeClientS();
 267             more |= evnt->checkForWork();
 268             IOTimeClientE();
 269
 270             if (ISSETP(&fFlags, kLoopTerminate))
 271                 goto abort;
 272             else if (fFlags & kLoopRestart) {
 273                 more = true;
 274                 break;
 275             }
 276         }
 277     } while (more);
 278
 279     res = true;
 280     IOTimeWorkE();
 281
 282 abort:
 283     openGate();
 284     return res;
 285 }
 286
 287 /* virtual */ void IOWorkLoop::threadMain()
 288 {
 289     do {
 290         if ( !runEventSources() )
 291             goto exitThread;
 292
 293         IOInterruptState is = IOSimpleLockLockDisableInterrupt(workToDoLock);
 294         if ( !ISSETP(&fFlags, kLoopTerminate) && !workToDo) {
 295             assert_wait((void *) &workToDo, false);
 296             IOSimpleLockUnlockEnableInterrupt(workToDoLock, is);
 297
 298             thread_continue_t cptr = OSMemberFunctionCast(
 299                     thread_continue_t, this, &IOWorkLoop::threadMain);
 300             thread_block_parameter(cptr, this);
 301             /* NOTREACHED */
 302         }
 303
 304         // At this point we either have work to do or we need
 305         // to commit suicide.  But no matter
 306         // Clear the simple lock and retore the interrupt state
 307         IOSimpleLockUnlockEnableInterrupt(workToDoLock, is);
 308     } while(workToDo);
 309
 310 exitThread:
 311     workThread = 0;     // Say we don't have a loop and free ourselves
 312     free();
 313     IOExitThread();
 314 }
 315
 316 IOThread IOWorkLoop::getThread() const
 317 {
 318     return workThread;
 319 }
 320
 321 bool IOWorkLoop::onThread() const
 322 {
 323     return (IOThreadSelf() == workThread);
 324 }
 325
 326 bool IOWorkLoop::inGate() const
 327 {
 328     return IORecursiveLockHaveLock(gateLock);
 329 }
 330
 331 // Internal APIs used by event sources to control the thread
 332 void IOWorkLoop::signalWorkAvailable()
 333 {
 334     if (workToDoLock) {
 335         IOInterruptState is = IOSimpleLockLockDisableInterrupt(workToDoLock);
 336         workToDo = true;
 337         thread_wakeup_one((void *) &workToDo);
 338         IOSimpleLockUnlockEnableInterrupt(workToDoLock, is);
 339     }
 340 }
 341
 342 void IOWorkLoop::openGate()
 343 {
 344     IORecursiveLockUnlock(gateLock);
 345 }
 346
 347 void IOWorkLoop::closeGate()
 348 {
 349     IORecursiveLockLock(gateLock);
 350 }
 351
 352 bool IOWorkLoop::tryCloseGate()
 353 {
 354     return IORecursiveLockTryLock(gateLock) != 0;
 355 }
 356
 357 int IOWorkLoop::sleepGate(void *event, UInt32 interuptibleType)
 358 {
 359     return IORecursiveLockSleep(gateLock, event, interuptibleType);
 360 }
 361
 362 void IOWorkLoop::wakeupGate(void *event, bool oneThread)
 363 {
 364     IORecursiveLockWakeup(gateLock, event, oneThread);
 365 }
 366
 367 IOReturn IOWorkLoop::runAction(Action inAction, OSObject *target,
 368                                   void *arg0, void *arg1,
 369                                   void *arg2, void *arg3)
 370 {
 371     IOReturn res;
 372
 373     // closeGate is recursive so don't worry if we already hold the lock.
 374     closeGate();
 375     res = (*inAction)(target, arg0, arg1, arg2, arg3);
 376     openGate();
 377
 378     return res;
 379 }
 380
 381 IOReturn IOWorkLoop::_maintRequest(void *inC, void *inD, void *, void *)
 382 {
 383     maintCommandEnum command = (maintCommandEnum) (vm_address_t) inC;
 384     IOEventSource *inEvent = (IOEventSource *) inD;
 385     IOReturn res = kIOReturnSuccess;
 386
 387     switch (command)
 388     {
 389     case mAddEvent:
 390         if (!inEvent->getWorkLoop()) {
 391             SETP(&fFlags, kLoopRestart);
 392
 393             inEvent->retain();
 394             inEvent->setWorkLoop(this);
 395             inEvent->setNext(0);
 396
 397             if (!eventChain)
 398                 eventChain = inEvent;
 399             else {
 400                 IOEventSource *event, *next;
 401
 402                 for (event = eventChain; (next = event->getNext()); event = next)
 403                     ;
 404                 event->setNext(inEvent);
 405             }
 406         }
 407         break;
 408
 409     case mRemoveEvent:
 410         if (inEvent->getWorkLoop()) {
 411             if (eventChain == inEvent)
 412                 eventChain = inEvent->getNext();
 413             else {
 414                 IOEventSource *event, *next;
 415
 416                 event = eventChain;
 417                 while ((next = event->getNext()) && next != inEvent)
 418                     event = next;
 419
 420                 if (!next) {
 421                     res = kIOReturnBadArgument;
 422                     break;
 423                 }
 424                 event->setNext(inEvent->getNext());
 425             }
 426
 427             inEvent->setWorkLoop(0);
 428             inEvent->setNext(0);
 429             inEvent->release();
 430             SETP(&fFlags, kLoopRestart);
 431         }
 432         break;
 433
 434     default:
 435         return kIOReturnUnsupported;
 436     }
 437
 438     return res;
 439 }