xnu-3248.60.10.tar.gz

[apple/xnu.git] / iokit / Kernel / IOWorkLoop.cpp

diff --git a/iokit/Kernel/IOWorkLoop.cpp b/iokit/Kernel/IOWorkLoop.cpp
index 4108eaac9930d4faf401676750c65a5e0c3f454a..6207b1ea1be3a465720b954cebd2879f7d09d574 100644 (file)
--- a/iokit/Kernel/IOWorkLoop.cpp
+++ b/iokit/Kernel/IOWorkLoop.cpp
@@ -1,46 +1,55 @@
 /*
 /*

- * Copyright (c) 1998-2000 Apple Computer, Inc. All rights reserved.
+ * Copyright (c) 1998-2010 Apple Inc. All rights reserved.

  *
  *

- * @APPLE_LICENSE_HEADER_START@
+ * @APPLE_OSREFERENCE_LICENSE_HEADER_START@

  * 
  * 

- * The contents of this file constitute Original Code as defined in and
- * are subject to the Apple Public Source License Version 1.1 (the
- * "License").  You may not use this file except in compliance with the
- * License.  Please obtain a copy of the License at
- * http://www.apple.com/publicsource and read it before using this file.
+ * This file contains Original Code and/or Modifications of Original Code
+ * as defined in and that are subject to the Apple Public Source License
+ * Version 2.0 (the 'License'). You may not use this file except in
+ * compliance with the License. The rights granted to you under the License
+ * may not be used to create, or enable the creation or redistribution of,
+ * unlawful or unlicensed copies of an Apple operating system, or to
+ * circumvent, violate, or enable the circumvention or violation of, any
+ * terms of an Apple operating system software license agreement.

  * 
  * 

- * This Original Code and all software distributed under the License are
- * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
+ * Please obtain a copy of the License at
+ * http://www.opensource.apple.com/apsl/ and read it before using this file.
+ * 
+ * The Original Code and all software distributed under the License are
+ * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER

  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,

- * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
- * License for the specific language governing rights and limitations
- * under the License.
+ * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
+ * Please see the License for the specific language governing rights and
+ * limitations under the License.

  * 
  * 

- * @APPLE_LICENSE_HEADER_END@
+ * @APPLE_OSREFERENCE_LICENSE_HEADER_END@

  */
  */

-/*
-Copyright (c) 1998 Apple Computer, Inc.  All rights reserved.

 
 

-HISTORY
-    1998-7-13  Godfrey van der Linden(gvdl)
-        Created.
-*/
+#include <pexpert/pexpert.h>

 #include <IOKit/IOWorkLoop.h>
 #include <IOKit/IOEventSource.h>
 #include <IOKit/IOInterruptEventSource.h>
 #include <IOKit/IOCommandGate.h>
 #include <IOKit/IOTimeStamp.h>
 #include <IOKit/IOWorkLoop.h>
 #include <IOKit/IOEventSource.h>
 #include <IOKit/IOInterruptEventSource.h>
 #include <IOKit/IOCommandGate.h>
 #include <IOKit/IOTimeStamp.h>

+#include <IOKit/IOKitDebug.h>
+#include <libkern/OSDebug.h>
+#include <kern/thread.h>

 
 #define super OSObject
 
 OSDefineMetaClassAndStructors(IOWorkLoop, OSObject);
 
 // Block of unused functions intended for future use
 
 #define super OSObject
 
 OSDefineMetaClassAndStructors(IOWorkLoop, OSObject);
 
 // Block of unused functions intended for future use

-OSMetaClassDefineReservedUsed(IOWorkLoop, 0);
-
+#if __LP64__
+OSMetaClassDefineReservedUnused(IOWorkLoop, 0);

 OSMetaClassDefineReservedUnused(IOWorkLoop, 1);
 OSMetaClassDefineReservedUnused(IOWorkLoop, 2);
 OSMetaClassDefineReservedUnused(IOWorkLoop, 1);
 OSMetaClassDefineReservedUnused(IOWorkLoop, 2);

+#else
+OSMetaClassDefineReservedUsed(IOWorkLoop, 0);
+OSMetaClassDefineReservedUsed(IOWorkLoop, 1);
+OSMetaClassDefineReservedUsed(IOWorkLoop, 2);
+#endif

 OSMetaClassDefineReservedUnused(IOWorkLoop, 3);
 OSMetaClassDefineReservedUnused(IOWorkLoop, 4);
 OSMetaClassDefineReservedUnused(IOWorkLoop, 5);
 OSMetaClassDefineReservedUnused(IOWorkLoop, 3);
 OSMetaClassDefineReservedUnused(IOWorkLoop, 4);
 OSMetaClassDefineReservedUnused(IOWorkLoop, 5);


@@ -49,59 +58,152 @@ OSMetaClassDefineReservedUnused(IOWorkLoop, 7);
 
 enum IOWorkLoopState { kLoopRestart = 0x1, kLoopTerminate = 0x2 };
 static inline void SETP(void *addr, unsigned int flag)
 
 enum IOWorkLoopState { kLoopRestart = 0x1, kLoopTerminate = 0x2 };
 static inline void SETP(void *addr, unsigned int flag)

-    { unsigned int *num = (unsigned int *) addr; *num |= flag; }
+    { unsigned char *num = (unsigned char *) addr; *num |= flag; }

 static inline void CLRP(void *addr, unsigned int flag)
 static inline void CLRP(void *addr, unsigned int flag)

-    { unsigned int *num = (unsigned int *) addr; *num &= ~flag; }
+    { unsigned char *num = (unsigned char *) addr; *num &= ~flag; }

 static inline bool ISSETP(void *addr, unsigned int flag)
 static inline bool ISSETP(void *addr, unsigned int flag)

-    { unsigned int *num = (unsigned int *) addr; return (*num & flag) != 0; }
+    { unsigned char *num = (unsigned char *) addr; return (*num & flag) != 0; }

 
 #define fFlags loopRestart
 
 
 #define fFlags loopRestart
 

-bool IOWorkLoop::init()
-{
-    // The super init and gateLock allocation MUST be done first
-    if ( !super::init() )
-        return false;
+#define passiveEventChain      reserved->passiveEventChain

 
 

-    if ( !(gateLock = IORecursiveLockAlloc()) )
-        return false;
+#if IOKITSTATS

 
 

-    if ( !(workToDoLock = IOSimpleLockAlloc()) )
-        return false;
+#define IOStatisticsRegisterCounter() \
+do { \
+       reserved->counter = IOStatistics::registerWorkLoop(this); \
+} while(0)

 
 

-    controlG = IOCommandGate::
-       commandGate(this, (IOCommandGate::Action) &IOWorkLoop::_maintRequest);
-    if ( !controlG )
-        return false;
+#define IOStatisticsUnregisterCounter() \
+do { \
+       if (reserved) \
+               IOStatistics::unregisterWorkLoop(reserved->counter); \
+} while(0)

 
 

-    IOSimpleLockInit(workToDoLock);
-    workToDo = false;
+#define IOStatisticsOpenGate() \
+do { \
+       IOStatistics::countWorkLoopOpenGate(reserved->counter); \
+} while(0)

 
 

-    // Point the controlGate at the workLoop.  Usually addEventSource
-    // does this automatically.  The problem is in this case addEventSource
-    // uses the control gate and it has to be bootstrapped.
-    controlG->setWorkLoop(this);
-    if (addEventSource(controlG) != kIOReturnSuccess)
-        return false;
+#define IOStatisticsCloseGate() \
+do { \
+       IOStatistics::countWorkLoopCloseGate(reserved->counter); \
+} while(0)
+
+#define IOStatisticsAttachEventSource() \
+do { \
+       IOStatistics::attachWorkLoopEventSource(reserved->counter, inEvent->reserved->counter); \
+} while(0)
+
+#define IOStatisticsDetachEventSource() \
+do { \
+       IOStatistics::detachWorkLoopEventSource(reserved->counter, inEvent->reserved->counter); \
+} while(0)
+
+#else

 
 

-    workThread = IOCreateThread((thread_continue_t)threadMainContinuation, this);
-    if (!workThread)
+#define IOStatisticsRegisterCounter()
+#define IOStatisticsUnregisterCounter()
+#define IOStatisticsOpenGate()
+#define IOStatisticsCloseGate()
+#define IOStatisticsAttachEventSource()
+#define IOStatisticsDetachEventSource()
+
+#endif /* IOKITSTATS */
+
+bool IOWorkLoop::init()
+{
+    // The super init and gateLock allocation MUST be done first.
+    if ( !super::init() )

         return false;
         return false;

+       
+       // Allocate our ExpansionData if it hasn't been allocated already.
+       if ( !reserved )
+       {
+               reserved = IONew(ExpansionData,1);
+               if ( !reserved )
+                       return false;
+               
+               bzero(reserved,sizeof(ExpansionData));
+       }
+       
+#if DEBUG
+       OSBacktrace ( reserved->allocationBacktrace, sizeof ( reserved->allocationBacktrace ) / sizeof ( reserved->allocationBacktrace[0] ) );
+#endif
+       
+    if ( gateLock == NULL ) {
+        if ( !( gateLock = IORecursiveLockAlloc()) )
+            return false;
+    }
+       
+    if ( workToDoLock == NULL ) {
+        if ( !(workToDoLock = IOSimpleLockAlloc()) )
+            return false;
+        IOSimpleLockInit(workToDoLock);
+        workToDo = false;
+    }
+
+    IOStatisticsRegisterCounter();
+
+    if ( controlG == NULL ) {
+        controlG = IOCommandGate::commandGate(
+            this,
+            OSMemberFunctionCast(
+                IOCommandGate::Action,
+                this,
+                &IOWorkLoop::_maintRequest));
+
+        if ( !controlG )
+            return false;
+        // Point the controlGate at the workLoop.  Usually addEventSource
+        // does this automatically.  The problem is in this case addEventSource
+        // uses the control gate and it has to be bootstrapped.
+        controlG->setWorkLoop(this);
+        if (addEventSource(controlG) != kIOReturnSuccess)
+            return false;
+    }

 
 

+    if ( workThread == NULL ) {
+        thread_continue_t cptr = OSMemberFunctionCast(
+            thread_continue_t,
+            this,
+            &IOWorkLoop::threadMain);
+        if (KERN_SUCCESS != kernel_thread_start(cptr, this, &workThread))
+            return false;
+    }
+
+    (void) thread_set_tag(workThread, THREAD_TAG_IOWORKLOOP);

     return true;
 }
 
 IOWorkLoop *
 IOWorkLoop::workLoop()
 {
     return true;
 }
 
 IOWorkLoop *
 IOWorkLoop::workLoop()
 {

-    IOWorkLoop *me = new IOWorkLoop;
-
-    if (me && !me->init()) {
-        me->release();
-        return 0;
-    }
+    return IOWorkLoop::workLoopWithOptions(0);
+}

 
 

-    return me;
+IOWorkLoop *
+IOWorkLoop::workLoopWithOptions(IOOptionBits options)
+{
+       IOWorkLoop *me = new IOWorkLoop;
+       
+       if (me && options) {
+               me->reserved = IONew(ExpansionData,1);
+               if (!me->reserved) {
+                       me->release();
+                       return 0;
+               }
+               bzero(me->reserved,sizeof(ExpansionData));
+               me->reserved->options = options;
+       }
+       
+       if (me && !me->init()) {
+               me->release();
+               return 0;
+       }
+       
+       return me;

 }
 
 // Free is called twice:
 }
 
 // Free is called twice:


@@ -114,7 +216,7 @@ void IOWorkLoop::free()
        IOInterruptState is;
 
        // If we are here then we must be trying to shut down this work loop
        IOInterruptState is;
 
        // If we are here then we must be trying to shut down this work loop

-       // in this case disable all of the event source, mark the loop for
+       // in this case disable all of the event source, mark the loop

        // as terminating and wakeup the work thread itself and return
        // Note: we hold the gate across the entire operation mainly for the 
        // benefit of our event sources so we can disable them cleanly.
        // as terminating and wakeup the work thread itself and return
        // Note: we hold the gate across the entire operation mainly for the 
        // benefit of our event sources so we can disable them cleanly.


@@ -140,11 +242,20 @@ void IOWorkLoop::free()
         }
         eventChain = 0;
 
         }
         eventChain = 0;
 

-       // Either we have a partial initialisation to clean up
-       // or we the workThread itself is performing hari-kari.
-       // either way clean up all of our resources and return.
+        for (event = passiveEventChain; event; event = next) {
+            next = event->getNext();
+            event->setWorkLoop(0);
+            event->setNext(0);
+            event->release();
+        }
+        passiveEventChain = 0;
+
+       // Either we have a partial initialization to clean up
+       // or the workThread itself is performing hari-kari.
+       // Either way clean up all of our resources and return.

        
        if (controlG) {
        
        if (controlG) {

+           controlG->workLoop = 0;

            controlG->release();
            controlG = 0;
        }
            controlG->release();
            controlG = 0;
        }


@@ -158,6 +269,13 @@ void IOWorkLoop::free()
            IORecursiveLockFree(gateLock);
            gateLock = 0;
        }
            IORecursiveLockFree(gateLock);
            gateLock = 0;
        }

+       
+       IOStatisticsUnregisterCounter();
+       
+       if (reserved) {
+           IODelete(reserved, ExpansionData, 1);
+           reserved = 0;
+       }

 
        super::free();
     }
 
        super::free();
     }


@@ -179,6 +297,9 @@ void IOWorkLoop::enableAllEventSources() const
 
     for (event = eventChain; event; event = event->getNext())
         event->enable();
 
     for (event = eventChain; event; event = event->getNext())
         event->enable();

+
+    for (event = passiveEventChain; event; event = event->getNext())
+        event->enable();

 }
 
 void IOWorkLoop::disableAllEventSources() const
 }
 
 void IOWorkLoop::disableAllEventSources() const


@@ -186,6 +307,10 @@ void IOWorkLoop::disableAllEventSources() const
     IOEventSource *event;
 
     for (event = eventChain; event; event = event->getNext())
     IOEventSource *event;
 
     for (event = eventChain; event; event = event->getNext())

+               event->disable();
+       
+       /* NOTE: controlG is in passiveEventChain since it's an IOCommandGate */
+    for (event = passiveEventChain; event; event = event->getNext())

         if (event != controlG) // Don't disable the control gate
             event->disable();
 }
         if (event != controlG) // Don't disable the control gate
             event->disable();
 }


@@ -193,7 +318,7 @@ void IOWorkLoop::disableAllEventSources() const
 void IOWorkLoop::enableAllInterrupts() const
 {
     IOEventSource *event;
 void IOWorkLoop::enableAllInterrupts() const
 {
     IOEventSource *event;

-
+       

     for (event = eventChain; event; event = event->getNext())
         if (OSDynamicCast(IOInterruptEventSource, event))
             event->enable();
     for (event = eventChain; event; event = event->getNext())
         if (OSDynamicCast(IOInterruptEventSource, event))
             event->enable();


@@ -202,90 +327,80 @@ void IOWorkLoop::enableAllInterrupts() const
 void IOWorkLoop::disableAllInterrupts() const
 {
     IOEventSource *event;
 void IOWorkLoop::disableAllInterrupts() const
 {
     IOEventSource *event;

-
+       

     for (event = eventChain; event; event = event->getNext())
         if (OSDynamicCast(IOInterruptEventSource, event))
             event->disable();
 }
 
     for (event = eventChain; event; event = event->getNext())
         if (OSDynamicCast(IOInterruptEventSource, event))
             event->disable();
 }
 

-#if KDEBUG
-#define IOTimeClientS()                                                        \
-do {                                                                   \
-    IOTimeStampStart(IODBG_WORKLOOP(IOWL_CLIENT),                      \
-                     (unsigned int) this, (unsigned int) event);       \
-} while(0)
-
-#define IOTimeClientE()                                                        \
-do {                                                                   \
-    IOTimeStampEnd(IODBG_WORKLOOP(IOWL_CLIENT),                                \
-                   (unsigned int) this, (unsigned int) event);         \
-} while(0)
-
-#define IOTimeWorkS()                                                  \
-do {                                                                   \
-    IOTimeStampStart(IODBG_WORKLOOP(IOWL_WORK),        (unsigned int) this);   \
-} while(0)
-
-#define IOTimeWorkE()                                                  \
-do {                                                                   \
-    IOTimeStampEnd(IODBG_WORKLOOP(IOWL_WORK),(unsigned int) this);     \
-} while(0)
-
-#else /* !KDEBUG */
-
-#define IOTimeClientS()
-#define IOTimeClientE()
-#define IOTimeWorkS()
-#define IOTimeWorkE()

 
 

-#endif /* KDEBUG */
-
-void IOWorkLoop::threadMainContinuation(IOWorkLoop *self)
+/* virtual */ bool IOWorkLoop::runEventSources()

 {
 {

-       self->threadMain();
+    bool res = false;
+    bool traceWL = (gIOKitTrace & kIOTraceWorkLoops) ? true : false;
+    bool traceES = (gIOKitTrace & kIOTraceEventSources) ? true : false;
+    
+    closeGate();
+    if (ISSETP(&fFlags, kLoopTerminate))
+               goto abort;
+       
+    if (traceWL)
+       IOTimeStampStartConstant(IODBG_WORKLOOP(IOWL_WORK), (uintptr_t) this);
+       
+    bool more;
+    do {
+               CLRP(&fFlags, kLoopRestart);
+               more = false;
+               IOInterruptState is = IOSimpleLockLockDisableInterrupt(workToDoLock);
+               workToDo = false;
+               IOSimpleLockUnlockEnableInterrupt(workToDoLock, is);
+               /* NOTE: only loop over event sources in eventChain. Bypass "passive" event sources for performance */
+               for (IOEventSource *evnt = eventChain; evnt; evnt = evnt->getNext()) {
+                       
+                       if (traceES)
+                               IOTimeStampStartConstant(IODBG_WORKLOOP(IOWL_CLIENT), (uintptr_t) this, (uintptr_t) evnt);
+                       
+                       more |= evnt->checkForWork();
+                       
+                       if (traceES)
+                               IOTimeStampEndConstant(IODBG_WORKLOOP(IOWL_CLIENT), (uintptr_t) this, (uintptr_t) evnt);
+                       
+                       if (ISSETP(&fFlags, kLoopTerminate))
+                               goto abort;
+                       else if (fFlags & kLoopRestart) {
+                               more = true;
+                               break;
+                       }
+               }
+    } while (more);
+       
+    res = true;
+       
+    if (traceWL)
+       IOTimeStampEndConstant(IODBG_WORKLOOP(IOWL_WORK), (uintptr_t) this);
+       
+abort:
+    openGate();
+    return res;

 }
 
 }
 

-void IOWorkLoop::threadMain()
+/* virtual */ void IOWorkLoop::threadMain()

 {
 {

-    CLRP(&fFlags, kLoopRestart);
-
-    for (;;) {
-        bool more;
-       IOInterruptState is;
-
-    IOTimeWorkS();
-
-        closeGate();
-        if (ISSETP(&fFlags, kLoopTerminate))
+restartThread:
+    do {
+       if ( !runEventSources() )

            goto exitThread;
 
            goto exitThread;
 

-        do {
-            workToDo = more = false;
-            for (IOEventSource *event = eventChain; event; event = event->getNext()) {
-
-            IOTimeClientS();
-                more |= event->checkForWork();
-            IOTimeClientE();
-
-               if (ISSETP(&fFlags, kLoopTerminate))
-                   goto exitThread;
-                else if (fFlags & kLoopRestart) {
-                   CLRP(&fFlags, kLoopRestart);
-                    continue;
-                }
-            }
-        } while (more);
-
-    IOTimeWorkE();
-
-        openGate();
-
-       is = IOSimpleLockLockDisableInterrupt(workToDoLock);
+       IOInterruptState is = IOSimpleLockLockDisableInterrupt(workToDoLock);

         if ( !ISSETP(&fFlags, kLoopTerminate) && !workToDo) {
            assert_wait((void *) &workToDo, false);
            IOSimpleLockUnlockEnableInterrupt(workToDoLock, is);
         if ( !ISSETP(&fFlags, kLoopTerminate) && !workToDo) {
            assert_wait((void *) &workToDo, false);
            IOSimpleLockUnlockEnableInterrupt(workToDoLock, is);

-
-           thread_block_parameter((thread_continue_t)threadMainContinuation, this);
+           thread_continue_t cptr = NULL;
+           if (!reserved || !(kPreciousStack & reserved->options))
+               cptr = OSMemberFunctionCast(
+                       thread_continue_t, this, &IOWorkLoop::threadMain);
+           thread_block_parameter(cptr, this);
+           goto restartThread;

            /* NOTREACHED */
        }
 
            /* NOTREACHED */
        }
 


@@ -293,16 +408,15 @@ void IOWorkLoop::threadMain()
        // to commit suicide.  But no matter 
        // Clear the simple lock and retore the interrupt state
        IOSimpleLockUnlockEnableInterrupt(workToDoLock, is);
        // to commit suicide.  But no matter 
        // Clear the simple lock and retore the interrupt state
        IOSimpleLockUnlockEnableInterrupt(workToDoLock, is);

-       if (workToDo)
-           continue;
-       else
-           break;
-    }
+    } while(workToDo);

 
 exitThread:
 
 exitThread:

+       thread_t thread = workThread;

     workThread = 0;    // Say we don't have a loop and free ourselves
     free();
     workThread = 0;    // Say we don't have a loop and free ourselves
     free();

-    IOExitThread();
+
+       thread_deallocate(thread);
+    (void) thread_terminate(thread);

 }
 
 IOThread IOWorkLoop::getThread() const
 }
 
 IOThread IOWorkLoop::getThread() const


@@ -333,22 +447,41 @@ void IOWorkLoop::signalWorkAvailable()
 
 void IOWorkLoop::openGate()
 {
 
 void IOWorkLoop::openGate()
 {

+    IOStatisticsOpenGate();

     IORecursiveLockUnlock(gateLock);
 }
 
 void IOWorkLoop::closeGate()
 {
     IORecursiveLockLock(gateLock);
     IORecursiveLockUnlock(gateLock);
 }
 
 void IOWorkLoop::closeGate()
 {
     IORecursiveLockLock(gateLock);

+    IOStatisticsCloseGate();

 }
 
 bool IOWorkLoop::tryCloseGate()
 {
 }
 
 bool IOWorkLoop::tryCloseGate()
 {

-    return IORecursiveLockTryLock(gateLock) != 0;
+    bool res = (IORecursiveLockTryLock(gateLock) != 0);
+    if (res) {
+        IOStatisticsCloseGate();
+    }
+    return res;

 }
 
 int IOWorkLoop::sleepGate(void *event, UInt32 interuptibleType)
 {
 }
 
 int IOWorkLoop::sleepGate(void *event, UInt32 interuptibleType)
 {

-    return IORecursiveLockSleep(gateLock, event, interuptibleType);
+    int res; 
+    IOStatisticsOpenGate();
+    res = IORecursiveLockSleep(gateLock, event, interuptibleType);
+    IOStatisticsCloseGate();
+    return res;
+}
+
+int IOWorkLoop::sleepGate(void *event, AbsoluteTime deadline, UInt32 interuptibleType)
+{
+    int res; 
+    IOStatisticsOpenGate();
+    res = IORecursiveLockSleepDeadline(gateLock, event, deadline, interuptibleType);
+    IOStatisticsCloseGate();
+    return res;

 }
 
 void IOWorkLoop::wakeupGate(void *event, bool oneThread)
 }
 
 void IOWorkLoop::wakeupGate(void *event, bool oneThread)


@@ -372,7 +505,7 @@ IOReturn IOWorkLoop::runAction(Action inAction, OSObject *target,
 
 IOReturn IOWorkLoop::_maintRequest(void *inC, void *inD, void *, void *)
 {
 
 IOReturn IOWorkLoop::_maintRequest(void *inC, void *inD, void *, void *)
 {

-    maintCommandEnum command = (maintCommandEnum) (vm_address_t) inC;
+    maintCommandEnum command = (maintCommandEnum) (uintptr_t) inC;

     IOEventSource *inEvent = (IOEventSource *) inD;
     IOReturn res = kIOReturnSuccess;
 
     IOEventSource *inEvent = (IOEventSource *) inD;
     IOReturn res = kIOReturnSuccess;
 


@@ -385,37 +518,79 @@ IOReturn IOWorkLoop::_maintRequest(void *inC, void *inD, void *, void *)
             inEvent->retain();
             inEvent->setWorkLoop(this);
             inEvent->setNext(0);
             inEvent->retain();
             inEvent->setWorkLoop(this);
             inEvent->setNext(0);

+
+               /* Check if this is a passive or active event source being added */
+               if (eventSourcePerformsWork(inEvent)) {
+               
+                   if (!eventChain)
+                   eventChain = inEvent;
+                   else {
+                   IOEventSource *event, *next;

     
     

-            if (!eventChain)
-                eventChain = inEvent;
+                       for (event = eventChain; (next = event->getNext()); event = next)
+                       ;
+                       event->setNext(inEvent);
+                       
+               }
+               
+            }

             else {
             else {

-                IOEventSource *event, *next;
+               
+                   if (!passiveEventChain)
+                   passiveEventChain = inEvent;
+                   else {
+                   IOEventSource *event, *next;

     
     

-                for (event = eventChain; (next = event->getNext()); event = next)
-                    ;
-                event->setNext(inEvent);
+                       for (event = passiveEventChain; (next = event->getNext()); event = next)
+                       ;
+                       event->setNext(inEvent);
+                       
+               }
+               

             }
             }

+            IOStatisticsAttachEventSource();

         }
         break;
 
     case mRemoveEvent:
         if (inEvent->getWorkLoop()) {
         }
         break;
 
     case mRemoveEvent:
         if (inEvent->getWorkLoop()) {

-            if (eventChain == inEvent)
-                eventChain = inEvent->getNext();
-            else {
-                IOEventSource *event, *next;
-    
-                event = eventChain;
-                while ((next = event->getNext()) && next != inEvent)
-                    event = next;
-    
-                if (!next) {
-                    res = kIOReturnBadArgument;
-                    break;
-                }
-                event->setNext(inEvent->getNext());
-            }
-    
+               IOStatisticsDetachEventSource();
+               
+               if (eventSourcePerformsWork(inEvent)) {
+                               if (eventChain == inEvent)
+                                       eventChain = inEvent->getNext();
+                               else {
+                                       IOEventSource *event, *next = 0;
+               
+                                       event = eventChain;
+                                       if (event) while ((next = event->getNext()) && (next != inEvent))
+                                               event = next;
+               
+                                       if (!next) {
+                                               res = kIOReturnBadArgument;
+                                               break;
+                                       }
+                                       event->setNext(inEvent->getNext());
+                               }
+               }
+               else {
+                               if (passiveEventChain == inEvent)
+                                       passiveEventChain = inEvent->getNext();
+                               else {
+                                       IOEventSource *event, *next = 0;
+               
+                                       event = passiveEventChain;
+                                       if (event) while ((next = event->getNext()) && (next != inEvent))
+                                               event = next;
+               
+                                       if (!next) {
+                                               res = kIOReturnBadArgument;
+                                               break;
+                                       }
+                                       event->setNext(inEvent->getNext());
+                               }
+               }
+               

             inEvent->setWorkLoop(0);
             inEvent->setNext(0);
             inEvent->release();
             inEvent->setWorkLoop(0);
             inEvent->setNext(0);
             inEvent->release();


@@ -429,3 +604,40 @@ IOReturn IOWorkLoop::_maintRequest(void *inC, void *inD, void *, void *)
 
     return res;
 }
 
     return res;
 }

+
+bool
+IOWorkLoop::eventSourcePerformsWork(IOEventSource *inEventSource)
+{
+       bool    result = true;
+
+       /*
+        * The idea here is to see if the subclass of IOEventSource has overridden checkForWork().
+        * The assumption is that if you override checkForWork(), you need to be
+        * active and not passive.
+        *
+        * We picked a known quantity controlG that does not override
+        * IOEventSource::checkForWork(), namely the IOCommandGate associated with
+        * the workloop to which this event source is getting attached.
+        * 
+        * We do a pointer comparison on the offset in the vtable for inNewEvent against
+        * the offset in the vtable for inReferenceEvent. This works because
+        * IOCommandGate's slot for checkForWork() has the address of
+        * IOEventSource::checkForWork() in it.
+        * 
+        * Think of OSMemberFunctionCast yielding the value at the vtable offset for
+        * checkForWork() here. We're just testing to see if it's the same or not.
+        *
+        */
+       if (controlG) {
+               void *  ptr1;
+               void *  ptr2;
+               
+               ptr1 = OSMemberFunctionCast(void*, inEventSource, &IOEventSource::checkForWork);
+               ptr2 = OSMemberFunctionCast(void*, controlG, &IOEventSource::checkForWork);
+               
+               if (ptr1 == ptr2)
+                       result = false;
+       }
+       
+    return result;
+}