This is xnu-8019. See this file in:
/*
 * Copyright (c) 1998-2000 Apple Computer, Inc. All rights reserved.
 *
 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
 *
 * 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.
 *
 * 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,
 * 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_OSREFERENCE_LICENSE_HEADER_END@
 */
#if DEBUG

#include "Tests.h"

#include <IOKit/IOCommandQueue.h>
#include <IOKit/IOInterruptEventSource.h>
#include <IOKit/IOWorkLoop.h>

#include <mach/sync_policy.h>

#define super OSObject

static TestDevice *sDevice;

static mach_timespec_t hundredMill = { 0, 100000000 };
static semaphore_port_t completeSema;

OSDefineMetaClassAndStructors(TestDevice, OSObject)

kern_return_t
TestDevice::enqueueCommand(bool sleep,
    TestDeviceAction act, int tag, void *dataP)
{
	return commQ->enqueueCommand(sleep, (void *) act, (void *) tag, dataP);
}

bool
TestDevice::init()
{
	if (!super::init()) {
		return false;
	}

	workLoop = IOWorkLoop::workLoop();
	if (!workLoop) {
		return false;
	}

	commQ = IOCommandQueue::commandQueue
	    (this, (IOCommandQueueAction) & rawCommandOccurred, 8);
	if (!commQ || kIOReturnSuccess != workLoop->addEventSource(commQ)) {
		return false;
	}

	intES = IOInterruptEventSource::interruptEventSource
	    (this, (IOInterruptEventAction) & interruptAction);
	if (!intES || kIOReturnSuccess != workLoop->addEventSource(intES)) {
		return false;
	}

	return true;
}

void
TestDevice::free()
{
	if (intES) {
		intES->release();
	}
	if (commQ) {
		commQ->release();
	}
	if (workLoop) {
		workLoop->release();
	}

	super::free();
}

void
TestDevice::rawCommandOccurred
(void *field0, void *field1, void *field2, void *)
{
	(*(TestDeviceAction) field0)(this, (int) field1, field2);
}

void
TestDevice::interruptAction(IOInterruptEventSource *, int count)
{
	logPrintf(("I(%d, %d) ", count, ++intCount));
}

void
TestDevice::producer1Action(int tag)
{
	logPrintf(("C1(%d) ", tag));
}

void
TestDevice::producer2Action(int tag, void *count)
{
	logPrintf(("C2(%d,%d) ", tag, (int) count));
	if (!(tag % 10)) {
		IOSleep(1000);
	}
}

void
TestDevice::alarm()
{
	intES->interruptOccurred(0, 0, 0);
	IOScheduleFunc((IOThreadFunc) alarm, (void *) this, hundredMill, 1);
}

static void
producer(void *inProducerId)
{
	int producerId = (int) inProducerId;
	TestDeviceAction command;
	int i;

	semaphore_wait(completeSema);

	if (producerId & 1) {
		command = (TestDeviceAction) sDevice->producer1Action;
	} else {
		command = (TestDeviceAction) sDevice->producer2Action;
	}

	for (i = 0; i < 5 * (producerId << 1); i++) {
		sDevice->enqueueCommand
		(true, command, i, (void *) (i % (producerId + 1)));
		if (!(i % (producerId + 1))) {
			/* cthread_yield() */;
		}
		logPrintf(("TestDevice(%d): %d\n", producerId, i));
	}

	logPrintf(("TestDevice: producer %d exiting\n", producerId));
	semaphore_signal(completeSema);

	IOExitThread(producerId);
}

void
testWorkLoop()
{
	int i;

	sDevice = new TestDevice;
	if (!sDevice || !sDevice->init()) {
		if (sDevice) {
			sDevice->free();
		}
		logPrintf(("TestDevice: couldn't create device instance\n"));
		return;
	}

	IOSleep(1000);

	IOScheduleFunc((IOThreadFunc) sDevice->alarm, sDevice, hundredMill, 1);

	IOSleep(2000);

	if (KERN_SUCCESS
	    != semaphore_create(kernel_task, &completeSema, SYNC_POLICY_FIFO, 4)) {
		return;
	}

	IOCreateThread(producer, (void *) 4);
	IOCreateThread(producer, (void *) 3);
	IOCreateThread(producer, (void *) 2);
	IOCreateThread(producer, (void *) 1);

	IOSleep(2000);

	for (i = 0; i < 4; i++) {
		semaphore_wait(completeSema);
	}

	IOUnscheduleFunc((IOThreadFunc) sDevice->alarm, sDevice);

	sDevice->free(); sDevice = 0;

	logPrintf(("TestDevice: exiting\n"));
}

#endif /* DEBUG */