[apple/xnu.git] / osfmk / kern / processor.c

/*
 * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
 *
 * @APPLE_LICENSE_HEADER_START@
 * 
 * Copyright (c) 1999-2003 Apple Computer, Inc.  All Rights Reserved.
 * 
 * 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. 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_LICENSE_HEADER_END@
 */
/*
 * @OSF_COPYRIGHT@
 */
/* 
 * Mach Operating System
 * Copyright (c) 1991,1990,1989,1988 Carnegie Mellon University
 * All Rights Reserved.
 * 
 * Permission to use, copy, modify and distribute this software and its
 * documentation is hereby granted, provided that both the copyright
 * notice and this permission notice appear in all copies of the
 * software, derivative works or modified versions, and any portions
 * thereof, and that both notices appear in supporting documentation.
 * 
 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
 * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
 * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
 * 
 * Carnegie Mellon requests users of this software to return to
 * 
 *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
 *  School of Computer Science
 *  Carnegie Mellon University
 *  Pittsburgh PA 15213-3890
 * 
 * any improvements or extensions that they make and grant Carnegie Mellon
 * the rights to redistribute these changes.
 */
/*
 */

/*
 *      processor.c: processor and processor_set manipulation routines.
 */

#include <cpus.h>

#include <mach/boolean.h>
#include <mach/policy.h>
#include <mach/processor_info.h>
#include <mach/vm_param.h>
#include <kern/cpu_number.h>
#include <kern/host.h>
#include <kern/machine.h>
#include <kern/misc_protos.h>
#include <kern/processor.h>
#include <kern/sched.h>
#include <kern/task.h>
#include <kern/thread.h>
#include <kern/ipc_host.h>
#include <kern/ipc_tt.h>
#include <ipc/ipc_port.h>
#include <kern/kalloc.h>

/*
 * Exported interface
 */
#include <mach/mach_host_server.h>

/*
 *      Exported variables.
 */
struct processor_set default_pset;
struct processor processor_array[NCPUS];

int             master_cpu = 0;

processor_t     master_processor;
processor_t     processor_ptr[NCPUS];

/* Forwards */
void    pset_init(
                processor_set_t pset);

void    processor_init(
                register processor_t    pr,
                int                     slot_num);

void    pset_quanta_set(
                processor_set_t         pset);

kern_return_t   processor_set_base(
                processor_set_t         pset,
                policy_t                policy,
                policy_base_t           base,
                boolean_t               change);

kern_return_t   processor_set_limit(
                processor_set_t         pset,
                policy_t                policy,
                policy_limit_t          limit,
                boolean_t               change);

kern_return_t   processor_set_things(
                processor_set_t         pset,
                mach_port_t             **thing_list,
                mach_msg_type_number_t  *count,
                int                     type);


/*
 *      Bootstrap the processor/pset system so the scheduler can run.
 */
void
pset_sys_bootstrap(void)
{
        register int    i;

        pset_init(&default_pset);
        for (i = 0; i < NCPUS; i++) {
                /*
                 *      Initialize processor data structures.
                 *      Note that cpu_to_processor(i) is processor_ptr[i].
                 */
                processor_ptr[i] = &processor_array[i];
                processor_init(processor_ptr[i], i);
        }
        master_processor = cpu_to_processor(master_cpu);
        master_processor->cpu_data = get_cpu_data();
        default_pset.active = TRUE;
}

/*
 *      Initialize the given processor_set structure.
 */

void pset_init(
        register processor_set_t        pset)
{
        register int    i;

        /* setup run queue */
        simple_lock_init(&pset->runq.lock, ETAP_THREAD_PSET_RUNQ);
        for (i = 0; i < NRQBM; i++)
            pset->runq.bitmap[i] = 0;
        setbit(MAXPRI - IDLEPRI, pset->runq.bitmap); 
        pset->runq.highq = IDLEPRI;
        pset->runq.urgency = pset->runq.count = 0;
        for (i = 0; i < NRQS; i++)
            queue_init(&pset->runq.queues[i]);

        queue_init(&pset->idle_queue);
        pset->idle_count = 0;
        queue_init(&pset->active_queue);
        simple_lock_init(&pset->sched_lock, ETAP_THREAD_PSET_IDLE);
        pset->run_count = 0;
        pset->mach_factor = pset->load_average = 0;
        pset->sched_load = 0;
        queue_init(&pset->processors);
        pset->processor_count = 0;
        simple_lock_init(&pset->processors_lock, ETAP_THREAD_PSET);
        queue_init(&pset->tasks);
        pset->task_count = 0;
        queue_init(&pset->threads);
        pset->thread_count = 0;
        pset->ref_count = 1;
        pset->active = FALSE;
        mutex_init(&pset->lock, ETAP_THREAD_PSET);
        pset->pset_self = IP_NULL;
        pset->pset_name_self = IP_NULL;
        pset->set_quanta = 1;

        for (i = 0; i <= NCPUS; i++)
            pset->machine_quanta[i] = 1;
}

/*
 *      Initialize the given processor structure for the processor in
 *      the slot specified by slot_num.
 */
void
processor_init(
        register processor_t    p,
        int                                             slot_num)
{
        register int    i;

        /* setup run queue */
        simple_lock_init(&p->runq.lock, ETAP_THREAD_PROC_RUNQ);
        for (i = 0; i < NRQBM; i++)
            p->runq.bitmap[i] = 0;
        setbit(MAXPRI - IDLEPRI, p->runq.bitmap); 
        p->runq.highq = IDLEPRI;
        p->runq.urgency = p->runq.count = 0;
        for (i = 0; i < NRQS; i++)
            queue_init(&p->runq.queues[i]);

        p->state = PROCESSOR_OFF_LINE;
        p->current_pri = MINPRI;
        p->next_thread = THREAD_NULL;
        p->idle_thread = THREAD_NULL;
        timer_call_setup(&p->quantum_timer, thread_quantum_expire, p);
        p->slice_quanta = 0;
        p->processor_set = PROCESSOR_SET_NULL;
        p->processor_set_next = PROCESSOR_SET_NULL;
        simple_lock_init(&p->lock, ETAP_THREAD_PROC);
        p->processor_self = IP_NULL;
        p->slot_num = slot_num;
}

/*
 *      pset_deallocate:
 *
 *      Remove one reference to the processor set.  Destroy processor_set
 *      if this was the last reference.
 */
void
pset_deallocate(
        processor_set_t pset)
{
        if (pset == PROCESSOR_SET_NULL)
                return;

        assert(pset == &default_pset);
        return;
}

/*
 *      pset_reference:
 *
 *      Add one reference to the processor set.
 */
void
pset_reference(
        processor_set_t pset)
{
        assert(pset == &default_pset);
}

#define pset_reference_locked(pset) assert(pset == &default_pset)

/*
 *      pset_remove_processor() removes a processor from a processor_set.
 *      It can only be called on the current processor.  Caller must
 *      hold lock on current processor and processor set.
 */
void
pset_remove_processor(
        processor_set_t pset,
        processor_t     processor)
{
        if (pset != processor->processor_set)
                panic("pset_remove_processor: wrong pset");

        queue_remove(&pset->processors, processor, processor_t, processors);
        processor->processor_set = PROCESSOR_SET_NULL;
        pset->processor_count--;
        pset_quanta_set(pset);
}

/*
 *      pset_add_processor() adds a  processor to a processor_set.
 *      It can only be called on the current processor.  Caller must
 *      hold lock on curent processor and on pset.  No reference counting on
 *      processors.  Processor reference to pset is implicit.
 */
void
pset_add_processor(
        processor_set_t pset,
        processor_t     processor)
{
        queue_enter(&pset->processors, processor, processor_t, processors);
        processor->processor_set = pset;
        pset->processor_count++;
        pset_quanta_set(pset);
}

/*
 *      pset_remove_task() removes a task from a processor_set.
 *      Caller must hold locks on pset and task (unless task has
 *      no references left, in which case just the pset lock is
 *      needed).  Pset reference count is not decremented;
 *      caller must explicitly pset_deallocate.
 */
void
pset_remove_task(
        processor_set_t pset,
        task_t          task)
{
        if (pset != task->processor_set)
                return;

        queue_remove(&pset->tasks, task, task_t, pset_tasks);
        task->processor_set = PROCESSOR_SET_NULL;
        pset->task_count--;
}

/*
 *      pset_add_task() adds a  task to a processor_set.
 *      Caller must hold locks on pset and task.  Pset references to
 *      tasks are implicit.
 */
void
pset_add_task(
        processor_set_t pset,
        task_t          task)
{
        queue_enter(&pset->tasks, task, task_t, pset_tasks);
        task->processor_set = pset;
        pset->task_count++;
        pset_reference_locked(pset);
}

/*
 *      pset_remove_thread() removes a thread from a processor_set.
 *      Caller must hold locks on pset and thread (but only if thread
 *  has outstanding references that could be used to lookup the pset).
 *  The pset reference count is not decremented; caller must explicitly
 *  pset_deallocate.
 */
void
pset_remove_thread(
        processor_set_t pset,
        thread_t        thread)
{
        queue_remove(&pset->threads, thread, thread_t, pset_threads);
        thread->processor_set = PROCESSOR_SET_NULL;
        pset->thread_count--;
}

/*
 *      pset_add_thread() adds a  thread to a processor_set.
 *      Caller must hold locks on pset and thread.  Pset references to
 *      threads are implicit.
 */
void
pset_add_thread(
        processor_set_t pset,
        thread_t        thread)
{
        queue_enter(&pset->threads, thread, thread_t, pset_threads);
        thread->processor_set = pset;
        pset->thread_count++;
        pset_reference_locked(pset);
}

/*
 *      thread_change_psets() changes the pset of a thread.  Caller must
 *      hold locks on both psets and thread.  The old pset must be
 *      explicitly pset_deallocat()'ed by caller.
 */
void
thread_change_psets(
        thread_t        thread,
        processor_set_t old_pset,
        processor_set_t new_pset)
{
        queue_remove(&old_pset->threads, thread, thread_t, pset_threads);
        old_pset->thread_count--;
        queue_enter(&new_pset->threads, thread, thread_t, pset_threads);
        thread->processor_set = new_pset;
        new_pset->thread_count++;
        pset_reference_locked(new_pset);
}       


kern_return_t
processor_info_count(
        processor_flavor_t      flavor,
        mach_msg_type_number_t  *count)
{
        kern_return_t           kr;

        switch (flavor) {
        case PROCESSOR_BASIC_INFO:
                *count = PROCESSOR_BASIC_INFO_COUNT;
                return KERN_SUCCESS;
        case PROCESSOR_CPU_LOAD_INFO:
                *count = PROCESSOR_CPU_LOAD_INFO_COUNT;
                return KERN_SUCCESS;
        default:
                kr = cpu_info_count(flavor, count);
                return kr;
        }
}


kern_return_t
processor_info(
        register processor_t    processor,
        processor_flavor_t      flavor,
        host_t                  *host,
        processor_info_t        info,
        mach_msg_type_number_t  *count)
{
        register int    i, slot_num, state;
        register processor_basic_info_t         basic_info;
        register processor_cpu_load_info_t      cpu_load_info;
        kern_return_t   kr;

        if (processor == PROCESSOR_NULL)
                return(KERN_INVALID_ARGUMENT);

        slot_num = processor->slot_num;

        switch (flavor) {

        case PROCESSOR_BASIC_INFO:
          {
            if (*count < PROCESSOR_BASIC_INFO_COUNT)
              return(KERN_FAILURE);

            basic_info = (processor_basic_info_t) info;
            basic_info->cpu_type = machine_slot[slot_num].cpu_type;
            basic_info->cpu_subtype = machine_slot[slot_num].cpu_subtype;
            state = processor->state;
            if (state == PROCESSOR_OFF_LINE)
              basic_info->running = FALSE;
            else
              basic_info->running = TRUE;
            basic_info->slot_num = slot_num;
            if (processor == master_processor) 
              basic_info->is_master = TRUE;
            else
              basic_info->is_master = FALSE;

            *count = PROCESSOR_BASIC_INFO_COUNT;
            *host = &realhost;
            return(KERN_SUCCESS);
          }
        case PROCESSOR_CPU_LOAD_INFO:
          {
            if (*count < PROCESSOR_CPU_LOAD_INFO_COUNT)
              return(KERN_FAILURE);

            cpu_load_info = (processor_cpu_load_info_t) info;
            for (i=0;i<CPU_STATE_MAX;i++)
              cpu_load_info->cpu_ticks[i] = machine_slot[slot_num].cpu_ticks[i];

            *count = PROCESSOR_CPU_LOAD_INFO_COUNT;
            *host = &realhost;
            return(KERN_SUCCESS);
          }
        default:
          {
            kr=cpu_info(flavor, slot_num, info, count);
            if (kr == KERN_SUCCESS)
                *host = &realhost;                 
            return(kr);
          }
        }
}

kern_return_t
processor_start(
        processor_t     processor)
{
        int     state;
        spl_t   s;
        kern_return_t   kr;

        if (processor == PROCESSOR_NULL)
                return(KERN_INVALID_ARGUMENT);

        if (processor == master_processor) {
                thread_bind(current_thread(), processor);
                thread_block(THREAD_CONTINUE_NULL);
                kr = cpu_start(processor->slot_num);
                thread_bind(current_thread(), PROCESSOR_NULL);

                return(kr);
        }

        s = splsched();
        processor_lock(processor);

        state = processor->state;
        if (state != PROCESSOR_OFF_LINE) {
                processor_unlock(processor);
                splx(s);
                return(KERN_FAILURE);
        }
        processor->state = PROCESSOR_START;
        processor_unlock(processor);
        splx(s);

        if (processor->next_thread == THREAD_NULL) {
                thread_t                thread;   
                extern void             start_cpu_thread(void);
        
                thread = kernel_thread_with_priority(
                                                                        kernel_task, MAXPRI_KERNEL,
                                                                                start_cpu_thread, TRUE, FALSE);

                s = splsched();
                thread_lock(thread);
                thread_bind_locked(thread, processor);
                thread_go_locked(thread, THREAD_AWAKENED);
                (void)rem_runq(thread);
                processor->next_thread = thread;
                thread_unlock(thread);
                splx(s);
        }

        kr = cpu_start(processor->slot_num);

        if (kr != KERN_SUCCESS) {
                s = splsched();
                processor_lock(processor);
                processor->state = PROCESSOR_OFF_LINE;
                processor_unlock(processor);
                splx(s);
        }

        return(kr);
}

kern_return_t
processor_exit(
        processor_t     processor)
{
        if (processor == PROCESSOR_NULL)
                return(KERN_INVALID_ARGUMENT);

        return(processor_shutdown(processor));
}

kern_return_t
processor_control(
        processor_t             processor,
        processor_info_t        info,
        mach_msg_type_number_t  count)
{
        if (processor == PROCESSOR_NULL)
                return(KERN_INVALID_ARGUMENT);

        return(cpu_control(processor->slot_num, info, count));
}

/*
 *      Precalculate the appropriate timesharing quanta based on load.  The
 *      index into machine_quanta is the number of threads on the
 *      processor set queue.  It is limited to the number of processors in
 *      the set.
 */

void
pset_quanta_set(
        processor_set_t         pset)
{
        register int    i, count = pset->processor_count;

        for (i = 1; i <= count; i++)
                pset->machine_quanta[i] = (count + (i / 2)) / i;

        pset->machine_quanta[0] = pset->machine_quanta[1];

        pset_quanta_update(pset);
}
            
kern_return_t
processor_set_create(
        host_t  host,
        processor_set_t *new_set,
        processor_set_t *new_name)
{
#ifdef  lint
        host++; new_set++; new_name++;
#endif  /* lint */
        return(KERN_FAILURE);
}

kern_return_t
processor_set_destroy(
        processor_set_t pset)
{
#ifdef  lint
        pset++;
#endif  /* lint */
        return(KERN_FAILURE);
}

kern_return_t
processor_get_assignment(
        processor_t     processor,
        processor_set_t *pset)
{
        int state;

        state = processor->state;
        if (state == PROCESSOR_SHUTDOWN || state == PROCESSOR_OFF_LINE)
                return(KERN_FAILURE);

        *pset = processor->processor_set;
        pset_reference(*pset);
        return(KERN_SUCCESS);
}

kern_return_t
processor_set_info(
        processor_set_t         pset,
        int                     flavor,
        host_t                  *host,
        processor_set_info_t    info,
        mach_msg_type_number_t  *count)
{
        if (pset == PROCESSOR_SET_NULL)
                return(KERN_INVALID_ARGUMENT);

        if (flavor == PROCESSOR_SET_BASIC_INFO) {
                register processor_set_basic_info_t     basic_info;

                if (*count < PROCESSOR_SET_BASIC_INFO_COUNT)
                        return(KERN_FAILURE);

                basic_info = (processor_set_basic_info_t) info;
                basic_info->processor_count = pset->processor_count;
                basic_info->default_policy = POLICY_TIMESHARE;

                *count = PROCESSOR_SET_BASIC_INFO_COUNT;
                *host = &realhost;
                return(KERN_SUCCESS);
        }
        else if (flavor == PROCESSOR_SET_TIMESHARE_DEFAULT) {
                register policy_timeshare_base_t        ts_base;

                if (*count < POLICY_TIMESHARE_BASE_COUNT)
                        return(KERN_FAILURE);

                ts_base = (policy_timeshare_base_t) info;
                ts_base->base_priority = BASEPRI_DEFAULT;

                *count = POLICY_TIMESHARE_BASE_COUNT;
                *host = &realhost;
                return(KERN_SUCCESS);
        }
        else if (flavor == PROCESSOR_SET_FIFO_DEFAULT) {
                register policy_fifo_base_t             fifo_base;

                if (*count < POLICY_FIFO_BASE_COUNT)
                        return(KERN_FAILURE);

                fifo_base = (policy_fifo_base_t) info;
                fifo_base->base_priority = BASEPRI_DEFAULT;

                *count = POLICY_FIFO_BASE_COUNT;
                *host = &realhost;
                return(KERN_SUCCESS);
        }
        else if (flavor == PROCESSOR_SET_RR_DEFAULT) {
                register policy_rr_base_t               rr_base;

                if (*count < POLICY_RR_BASE_COUNT)
                        return(KERN_FAILURE);

                rr_base = (policy_rr_base_t) info;
                rr_base->base_priority = BASEPRI_DEFAULT;
                rr_base->quantum = 1;

                *count = POLICY_RR_BASE_COUNT;
                *host = &realhost;
                return(KERN_SUCCESS);
        }
        else if (flavor == PROCESSOR_SET_TIMESHARE_LIMITS) {
                register policy_timeshare_limit_t       ts_limit;

                if (*count < POLICY_TIMESHARE_LIMIT_COUNT)
                        return(KERN_FAILURE);

                ts_limit = (policy_timeshare_limit_t) info;
                ts_limit->max_priority = MAXPRI_STANDARD;

                *count = POLICY_TIMESHARE_LIMIT_COUNT;
                *host = &realhost;
                return(KERN_SUCCESS);
        }
        else if (flavor == PROCESSOR_SET_FIFO_LIMITS) {
                register policy_fifo_limit_t            fifo_limit;

                if (*count < POLICY_FIFO_LIMIT_COUNT)
                        return(KERN_FAILURE);

                fifo_limit = (policy_fifo_limit_t) info;
                fifo_limit->max_priority = MAXPRI_STANDARD;

                *count = POLICY_FIFO_LIMIT_COUNT;
                *host = &realhost;
                return(KERN_SUCCESS);
        }
        else if (flavor == PROCESSOR_SET_RR_LIMITS) {
                register policy_rr_limit_t              rr_limit;

                if (*count < POLICY_RR_LIMIT_COUNT)
                        return(KERN_FAILURE);

                rr_limit = (policy_rr_limit_t) info;
                rr_limit->max_priority = MAXPRI_STANDARD;

                *count = POLICY_RR_LIMIT_COUNT;
                *host = &realhost;
                return(KERN_SUCCESS);
        }
        else if (flavor == PROCESSOR_SET_ENABLED_POLICIES) {
                register int                            *enabled;

                if (*count < (sizeof(*enabled)/sizeof(int)))
                        return(KERN_FAILURE);

                enabled = (int *) info;
                *enabled = POLICY_TIMESHARE | POLICY_RR | POLICY_FIFO;

                *count = sizeof(*enabled)/sizeof(int);
                *host = &realhost;
                return(KERN_SUCCESS);
        }


        *host = HOST_NULL;
        return(KERN_INVALID_ARGUMENT);
}

/*
 *      processor_set_statistics
 *
 *      Returns scheduling statistics for a processor set. 
 */
kern_return_t 
processor_set_statistics(
        processor_set_t         pset,
        int                     flavor,
        processor_set_info_t    info,
        mach_msg_type_number_t  *count)
{
        if (pset == PROCESSOR_SET_NULL)
                return (KERN_INVALID_PROCESSOR_SET);

        if (flavor == PROCESSOR_SET_LOAD_INFO) {
                register processor_set_load_info_t     load_info;

                if (*count < PROCESSOR_SET_LOAD_INFO_COUNT)
                        return(KERN_FAILURE);

                load_info = (processor_set_load_info_t) info;

                pset_lock(pset);
                load_info->task_count = pset->task_count;
                load_info->thread_count = pset->thread_count;
                load_info->mach_factor = pset->mach_factor;
                load_info->load_average = pset->load_average;
                pset_unlock(pset);

                *count = PROCESSOR_SET_LOAD_INFO_COUNT;
                return(KERN_SUCCESS);
        }

        return(KERN_INVALID_ARGUMENT);
}

/*
 *      processor_set_max_priority:
 *
 *      Specify max priority permitted on processor set.  This affects
 *      newly created and assigned threads.  Optionally change existing
 *      ones.
 */
kern_return_t
processor_set_max_priority(
        processor_set_t pset,
        int             max_priority,
        boolean_t       change_threads)
{
        return (KERN_INVALID_ARGUMENT);
}

/*
 *      processor_set_policy_enable:
 *
 *      Allow indicated policy on processor set.
 */

kern_return_t
processor_set_policy_enable(
        processor_set_t pset,
        int             policy)
{
        return (KERN_INVALID_ARGUMENT);
}

/*
 *      processor_set_policy_disable:
 *
 *      Forbid indicated policy on processor set.  Time sharing cannot
 *      be forbidden.
 */
kern_return_t
processor_set_policy_disable(
        processor_set_t pset,
        int             policy,
        boolean_t       change_threads)
{
        return (KERN_INVALID_ARGUMENT);
}

#define THING_TASK      0
#define THING_THREAD    1

/*
 *      processor_set_things:
 *
 *      Common internals for processor_set_{threads,tasks}
 */
kern_return_t
processor_set_things(
        processor_set_t         pset,
        mach_port_t             **thing_list,
        mach_msg_type_number_t  *count,
        int                     type)
{
        unsigned int actual;    /* this many things */
        int i;

        vm_size_t size, size_needed;
        vm_offset_t addr;

        if (pset == PROCESSOR_SET_NULL)
                return KERN_INVALID_ARGUMENT;

        size = 0; addr = 0;

        for (;;) {
                pset_lock(pset);
                if (!pset->active) {
                        pset_unlock(pset);
                        return KERN_FAILURE;
                }

                if (type == THING_TASK)
                        actual = pset->task_count;
                else
                        actual = pset->thread_count;

                /* do we have the memory we need? */

                size_needed = actual * sizeof(mach_port_t);
                if (size_needed <= size)
                        break;

                /* unlock the pset and allocate more memory */
                pset_unlock(pset);

                if (size != 0)
                        kfree(addr, size);

                assert(size_needed > 0);
                size = size_needed;

                addr = kalloc(size);
                if (addr == 0)
                        return KERN_RESOURCE_SHORTAGE;
        }

        /* OK, have memory and the processor_set is locked & active */

        switch (type) {
            case THING_TASK: {
                task_t *tasks = (task_t *) addr;
                task_t task;

                for (i = 0, task = (task_t) queue_first(&pset->tasks);
                     !queue_end(&pset->tasks, (queue_entry_t) task);
                         task = (task_t) queue_next(&task->pset_tasks)) {
                        
                        task_lock(task);
                        if (task->ref_count > 0) {
                                /* take ref for convert_task_to_port */
                                task_reference_locked(task);
                                tasks[i++] = task;
                        }
                        task_unlock(task);
                }
                break;
            }

            case THING_THREAD: {
                thread_act_t *thr_acts = (thread_act_t *) addr;
                thread_t thread;
                thread_act_t thr_act;

                for (i = 0, thread = (thread_t) queue_first(&pset->threads);
                         !queue_end(&pset->threads, (queue_entry_t)thread);
                 thread = (thread_t) queue_next(&thread->pset_threads)) {

                        thr_act = thread_lock_act(thread);
                        if (thr_act && thr_act->ref_count > 0) {
                                /* take ref for convert_act_to_port */
                                act_locked_act_reference(thr_act);
                                thr_acts[i++] = thr_act;
                        }
                        thread_unlock_act(thread);
                }
                break;
                }
        }
                
        /* can unlock processor set now that we have the task/thread refs */
        pset_unlock(pset);

        if (i < actual) {
                        actual = i;
                        size_needed = actual * sizeof(mach_port_t);
        }
        assert(i == actual);

        if (actual == 0) {
                /* no things, so return null pointer and deallocate memory */
                *thing_list = 0;
                *count = 0;

                if (size != 0)
                        kfree(addr, size);
        } else {
                /* if we allocated too much, must copy */

                if (size_needed < size) {
                        vm_offset_t newaddr;

                        newaddr = kalloc(size_needed);
                        if (newaddr == 0) {
                                switch (type) {
                                    case THING_TASK: {
                                        task_t *tasks = (task_t *) addr;

                                        for (i = 0; i < actual; i++)
                                                task_deallocate(tasks[i]);
                                        break;
                                    }

                                    case THING_THREAD: {
                                        thread_act_t *acts = (thread_act_t *) addr;

                                        for (i = 0; i < actual; i++)
                                                act_deallocate(acts[i]);
                                        break;
                                    }
                                }
                                kfree(addr, size);
                                return KERN_RESOURCE_SHORTAGE;
                        }

                        bcopy((char *) addr, (char *) newaddr, size_needed);
                        kfree(addr, size);
                        addr = newaddr;
                }

                *thing_list = (mach_port_t *) addr;
                *count = actual;

                /* do the conversion that Mig should handle */

                switch (type) {
                    case THING_TASK: {
                        task_t *tasks = (task_t *) addr;

                        for (i = 0; i < actual; i++)
                                (*thing_list)[i] = convert_task_to_port(tasks[i]);
                        break;
                    }

                    case THING_THREAD: {
                        thread_act_t *thr_acts = (thread_act_t *) addr;

                        for (i = 0; i < actual; i++)
                                (*thing_list)[i] = convert_act_to_port(thr_acts[i]);
                        break;
                    }
                }
        }

        return(KERN_SUCCESS);
}


/*
 *      processor_set_tasks:
 *
 *      List all tasks in the processor set.
 */
kern_return_t
processor_set_tasks(
        processor_set_t         pset,
        task_array_t            *task_list,
        mach_msg_type_number_t  *count)
{
    return(processor_set_things(pset, (mach_port_t **)task_list, count, THING_TASK));
}

/*
 *      processor_set_threads:
 *
 *      List all threads in the processor set.
 */
kern_return_t
processor_set_threads(
        processor_set_t         pset,
        thread_array_t          *thread_list,
        mach_msg_type_number_t  *count)
{
    return(processor_set_things(pset, (mach_port_t **)thread_list, count, THING_THREAD));
}

/*
 *      processor_set_base:
 *
 *      Specify per-policy base priority for a processor set.  Set processor
 *      set default policy to the given policy. This affects newly created
 *      and assigned threads.  Optionally change existing ones.
 */
kern_return_t
processor_set_base(
        processor_set_t         pset,
        policy_t                policy,
        policy_base_t           base,
        boolean_t               change)
{
        return (KERN_INVALID_ARGUMENT);
}

/*
 *      processor_set_limit:
 *
 *      Specify per-policy limits for a processor set.  This affects
 *      newly created and assigned threads.  Optionally change existing
 *      ones.
 */
kern_return_t
processor_set_limit(
        processor_set_t         pset,
        policy_t                policy,
        policy_limit_t          limit,
        boolean_t               change)
{
        return (KERN_POLICY_LIMIT);
}

/*
 *      processor_set_policy_control
 *
 *      Controls the scheduling attributes governing the processor set.
 *      Allows control of enabled policies, and per-policy base and limit
 *      priorities.
 */
kern_return_t
processor_set_policy_control(
        processor_set_t         pset,
        int                     flavor,
        processor_set_info_t    policy_info,
        mach_msg_type_number_t  count,
        boolean_t               change)
{
        return (KERN_INVALID_ARGUMENT);
}