xnu-344.32.tar.gz

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

/*
 * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
 *
 * @APPLE_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 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 OR NON-INFRINGEMENT.  Please see the
 * License for the specific language governing rights and limitations
 * under the License.
 * 
 * @APPLE_LICENSE_HEADER_END@
 */
/*
 * @OSF_FREE_COPYRIGHT@
 */
/*
 * Copyright (c) 1993 The University of Utah and
 * the Center for Software Science (CSS).  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.
 *
 * THE UNIVERSITY OF UTAH AND CSS ALLOW FREE USE OF THIS SOFTWARE IN ITS "AS
 * IS" CONDITION.  THE UNIVERSITY OF UTAH AND CSS DISCLAIM ANY LIABILITY OF
 * ANY KIND FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
 *
 * CSS requests users of this software to return to css-dist@cs.utah.edu any
 * improvements that they make and grant CSS redistribution rights.
 *
 *      Author: Bryan Ford, University of Utah CSS
 *
 *      Thread_Activation management routines
 */

#include <cpus.h>
#include <task_swapper.h>
#include <mach/kern_return.h>
#include <mach/alert.h>
#include <kern/etap_macros.h>
#include <kern/mach_param.h>
#include <kern/zalloc.h>
#include <kern/thread.h>
#include <kern/thread_swap.h>
#include <kern/task.h>
#include <kern/task_swap.h>
#include <kern/thread_act.h>
#include <kern/sched_prim.h>
#include <kern/misc_protos.h>
#include <kern/assert.h>
#include <kern/exception.h>
#include <kern/ipc_mig.h>
#include <kern/ipc_tt.h>
#include <kern/profile.h>
#include <kern/machine.h>
#include <kern/spl.h>
#include <kern/syscall_subr.h>
#include <kern/sync_lock.h>
#include <kern/mk_sp.h> /*** ??? fix so this can be removed ***/
#include <kern/processor.h>
#include <mach_prof.h>
#include <mach/rpc.h>

/*
 * Debugging printf control
 */
#if     MACH_ASSERT
unsigned int    watchacts =       0 /* WA_ALL */
                                    ;   /* Do-it-yourself & patchable */
#endif

/*
 * Track the number of times we need to swapin a thread to deallocate it.
 */
int act_free_swapin = 0;
boolean_t first_act;

/*
 * Forward declarations for functions local to this file.
 */
kern_return_t   act_abort( thread_act_t, boolean_t);
void            special_handler(ReturnHandler *, thread_act_t);
kern_return_t   act_set_state_locked(thread_act_t, int,
                                        thread_state_t,
                                        mach_msg_type_number_t);
kern_return_t   act_get_state_locked(thread_act_t, int,
                                        thread_state_t,
                                        mach_msg_type_number_t *);
void            act_set_astbsd(thread_act_t);
void            act_set_apc(thread_act_t);
void            act_user_to_kernel(thread_act_t);
void            act_ulock_release_all(thread_act_t thr_act);

void            install_special_handler_locked(thread_act_t);

static void             act_disable(thread_act_t);

struct thread_activation        pageout_act;

static zone_t   thr_act_zone;

/*
 * Thread interfaces accessed via a thread_activation:
 */


/*
 * Internal routine to terminate a thread.
 * Sometimes called with task already locked.
 */
kern_return_t
thread_terminate_internal(
        register thread_act_t   act)
{
        kern_return_t   result;
        thread_t                thread;

        thread = act_lock_thread(act);

        if (!act->active) {
                act_unlock_thread(act);
                return (KERN_TERMINATED);
        }

        act_disable(act);
        result = act_abort(act, FALSE);

        /* 
         * Make sure this thread enters the kernel
         * Must unlock the act, but leave the shuttle
         * captured in this act.
         */
        if (thread != current_thread()) {
                act_unlock(act);

                if (thread_stop(thread))
                        thread_unstop(thread);
                else
                        result = KERN_ABORTED;

                act_lock(act);
        }

        clear_wait(thread, act->inited? THREAD_INTERRUPTED: THREAD_AWAKENED);
        act_unlock_thread(act);

        return (result);
}

/*
 * Terminate a thread.
 */
kern_return_t
thread_terminate(
        register thread_act_t   act)
{
        kern_return_t   result;

        if (act == THR_ACT_NULL)
                return (KERN_INVALID_ARGUMENT);

        if (    (act->task == kernel_task       ||
                         act->kernel_loaded                     )       &&
                        act != current_act()                    )
                return (KERN_FAILURE);

        result = thread_terminate_internal(act);

        /*
         * If a kernel thread is terminating itself, force an AST here.
         * Kernel threads don't normally pass through the AST checking
         * code - and all threads finish their own termination in the
         * special handler APC.
         */
        if (    act->task == kernel_task        ||
                         act->kernel_loaded                     ) {
                assert(act == current_act());
                ast_taken(AST_APC, FALSE);
                panic("thread_terminate");
        }

        return (result);
}

/*
 * Suspend execution of the specified thread.
 * This is a recursive-style suspension of the thread, a count of
 * suspends is maintained.
 *
 * Called with act_lock held.
 */
void
thread_hold(
        register thread_act_t   act)
{
        thread_t        thread = act->thread;

        if (act->suspend_count++ == 0) {
                install_special_handler(act);
                if (    act->inited                                     &&
                                thread != THREAD_NULL           &&
                                thread->top_act == act          )
                        thread_wakeup_one(&act->suspend_count);
        }
}

/*
 * Decrement internal suspension count for thr_act, setting thread
 * runnable when count falls to zero.
 *
 * Called with act_lock held.
 */
void
thread_release(
        register thread_act_t   act)
{
        thread_t        thread = act->thread;

        if (    act->suspend_count > 0          &&
                        --act->suspend_count == 0       &&
                        thread != THREAD_NULL           &&
                        thread->top_act == act          ) {
                if (!act->inited) {
                        clear_wait(thread, THREAD_AWAKENED);
                        act->inited = TRUE;
                }
                else
                        thread_wakeup_one(&act->suspend_count);
        }
}

kern_return_t
thread_suspend(
        register thread_act_t   act)
{
        thread_t        thread;

        if (act == THR_ACT_NULL)
                return (KERN_INVALID_ARGUMENT);

        thread = act_lock_thread(act);

        if (!act->active) {
                act_unlock_thread(act);
                return (KERN_TERMINATED);
        }

        if (    act->user_stop_count++ == 0             &&
                        act->suspend_count++ == 0               ) {
                install_special_handler(act);
                if (    thread != current_thread()              &&
                                thread != THREAD_NULL                   &&
                                thread->top_act == act                  ) {
                        assert(act->inited);
                        thread_wakeup_one(&act->suspend_count);
                        act_unlock_thread(act);

                        thread_wait(thread);
                }
                else
                        act_unlock_thread(act);
        }
        else
                act_unlock_thread(act);

        return (KERN_SUCCESS);
}

kern_return_t
thread_resume(
        register thread_act_t   act)
{
        kern_return_t   result = KERN_SUCCESS;
        thread_t                thread;

        if (act == THR_ACT_NULL)
                return (KERN_INVALID_ARGUMENT);

        thread = act_lock_thread(act);

        if (act->active) {
                if (act->user_stop_count > 0) {
                        if (    --act->user_stop_count == 0             &&
                                        --act->suspend_count == 0               &&
                                        thread != THREAD_NULL                   &&
                                        thread->top_act == act                  ) {
                                if (!act->inited) {
                                        clear_wait(thread, THREAD_AWAKENED);
                                        act->inited = TRUE;
                                }
                                else
                                        thread_wakeup_one(&act->suspend_count);
                        }
                }
                else
                        result = KERN_FAILURE;
        }
        else
                result = KERN_TERMINATED;

        act_unlock_thread(act);

        return (result);
}

/* 
 * This routine walks toward the head of an RPC chain starting at
 * a specified thread activation. An alert bit is set and a special 
 * handler is installed for each thread it encounters.
 *
 * The target thread act and thread shuttle are already locked.
 */
kern_return_t
post_alert( 
        register thread_act_t   act,
        unsigned                                alert_bits)
{
        panic("post_alert");
}

/*
 *      thread_depress_abort:
 *
 *      Prematurely abort priority depression if there is one.
 */
kern_return_t
thread_depress_abort(
        register thread_act_t   thr_act)
{
    register thread_t           thread;
        kern_return_t                   result;

    if (thr_act == THR_ACT_NULL)
                return (KERN_INVALID_ARGUMENT);

    thread = act_lock_thread(thr_act);
    /* if activation is terminating, this operation is not meaningful */
    if (!thr_act->active) {
                act_unlock_thread(thr_act);

                return (KERN_TERMINATED);
    }

    result = _mk_sp_thread_depress_abort(thread, FALSE);

    act_unlock_thread(thr_act);

        return (result);
}


/*
 * Indicate that the activation should run its
 * special handler to detect the condition.
 *
 * Called with act_lock held.
 */
kern_return_t
act_abort(
        thread_act_t    act, 
        boolean_t       chain_break )
{
        thread_t        thread = act->thread;
        spl_t           s = splsched();

        assert(thread->top_act == act);

        thread_lock(thread);
        if (!(thread->state & TH_ABORT)) {
                thread->state |= TH_ABORT;
                install_special_handler_locked(act);
        } else {
                thread->state &= ~TH_ABORT_SAFELY;
        }
        thread_unlock(thread);
        splx(s);

        return (KERN_SUCCESS);
}
        
kern_return_t
thread_abort(
        register thread_act_t   act)
{
        kern_return_t   result;
        thread_t                thread;

        if (act == THR_ACT_NULL)
                return (KERN_INVALID_ARGUMENT);

        thread = act_lock_thread(act);

        if (!act->active) {
                act_unlock_thread(act);
                return (KERN_TERMINATED);
        }

        result = act_abort(act, FALSE);
        clear_wait(thread, THREAD_INTERRUPTED);
        act_unlock_thread(act);

        return (result);
}

kern_return_t
thread_abort_safely(
        thread_act_t    act)
{
        thread_t                thread;
        kern_return_t   ret;
        spl_t                   s;

        if (    act == THR_ACT_NULL )
                return (KERN_INVALID_ARGUMENT);

        thread = act_lock_thread(act);

        if (!act->active) {
                act_unlock_thread(act);
                return (KERN_TERMINATED);
        }

        s = splsched();
        thread_lock(thread);
        if (!thread->at_safe_point ||
                clear_wait_internal(thread, THREAD_INTERRUPTED) != KERN_SUCCESS) {
                if (!(thread->state & TH_ABORT)) {
                        thread->state |= (TH_ABORT|TH_ABORT_SAFELY);
                        install_special_handler_locked(act);
                }
        }
        thread_unlock(thread);
        splx(s);
                
        act_unlock_thread(act);

        return (KERN_SUCCESS);
}

/*** backward compatibility hacks ***/
#include <mach/thread_info.h>
#include <mach/thread_special_ports.h>
#include <ipc/ipc_port.h>
#include <mach/thread_act_server.h>

kern_return_t
thread_info(
        thread_act_t                    thr_act,
        thread_flavor_t                 flavor,
        thread_info_t                   thread_info_out,
        mach_msg_type_number_t  *thread_info_count)
{
        register thread_t               thread;
        kern_return_t                   result;

        if (thr_act == THR_ACT_NULL)
                return (KERN_INVALID_ARGUMENT);

        thread = act_lock_thread(thr_act);
        if (!thr_act->active) {
                act_unlock_thread(thr_act);

                return (KERN_TERMINATED);
        }

        result = thread_info_shuttle(thr_act, flavor,
                                        thread_info_out, thread_info_count);

        act_unlock_thread(thr_act);

        return (result);
}

/*
 *      Routine:        thread_get_special_port [kernel call]
 *      Purpose:
 *              Clones a send right for one of the thread's
 *              special ports.
 *      Conditions:
 *              Nothing locked.
 *      Returns:
 *              KERN_SUCCESS            Extracted a send right.
 *              KERN_INVALID_ARGUMENT   The thread is null.
 *              KERN_FAILURE            The thread is dead.
 *              KERN_INVALID_ARGUMENT   Invalid special port.
 */

kern_return_t
thread_get_special_port(
        thread_act_t    thr_act,
        int             which,
        ipc_port_t      *portp)
{
        ipc_port_t      *whichp;
        ipc_port_t      port;
        thread_t        thread;

#if     MACH_ASSERT
        if (watchacts & WA_PORT)
            printf("thread_get_special_port(thr_act=%x, which=%x port@%x=%x\n",
                thr_act, which, portp, (portp ? *portp : 0));
#endif  /* MACH_ASSERT */

        if (!thr_act)
                return KERN_INVALID_ARGUMENT;
        thread = act_lock_thread(thr_act);
        switch (which) {
                case THREAD_KERNEL_PORT:
                        whichp = &thr_act->ith_sself;
                        break;

                default:
                        act_unlock_thread(thr_act);
                        return KERN_INVALID_ARGUMENT;
        }

        if (!thr_act->active) {
                act_unlock_thread(thr_act);
                return KERN_FAILURE;
        }

        port = ipc_port_copy_send(*whichp);
        act_unlock_thread(thr_act);

        *portp = port;
        return KERN_SUCCESS;
}

/*
 *      Routine:        thread_set_special_port [kernel call]
 *      Purpose:
 *              Changes one of the thread's special ports,
 *              setting it to the supplied send right.
 *      Conditions:
 *              Nothing locked.  If successful, consumes
 *              the supplied send right.
 *      Returns:
 *              KERN_SUCCESS            Changed the special port.
 *              KERN_INVALID_ARGUMENT   The thread is null.
 *              KERN_FAILURE            The thread is dead.
 *              KERN_INVALID_ARGUMENT   Invalid special port.
 */

kern_return_t
thread_set_special_port(
        thread_act_t    thr_act,
        int             which,
        ipc_port_t      port)
{
        ipc_port_t      *whichp;
        ipc_port_t      old;
        thread_t        thread;

#if     MACH_ASSERT
        if (watchacts & WA_PORT)
                printf("thread_set_special_port(thr_act=%x,which=%x,port=%x\n",
                        thr_act, which, port);
#endif  /* MACH_ASSERT */

        if (thr_act == 0)
                return KERN_INVALID_ARGUMENT;

        thread = act_lock_thread(thr_act);
        switch (which) {
                case THREAD_KERNEL_PORT:
                        whichp = &thr_act->ith_self;
                        break;

                default:
                        act_unlock_thread(thr_act);
                        return KERN_INVALID_ARGUMENT;
        }

        if (!thr_act->active) {
                act_unlock_thread(thr_act);
                return KERN_FAILURE;
        }

        old = *whichp;
        *whichp = port;
        act_unlock_thread(thr_act);

        if (IP_VALID(old))
                ipc_port_release_send(old);
        return KERN_SUCCESS;
}

/*
 *  thread state should always be accessible by locking the thread
 *  and copying it.  The activation messes things up so for right
 *  now if it's not the top of the chain, use a special handler to
 *  get the information when the shuttle returns to the activation.
 */
kern_return_t
thread_get_state(
        register thread_act_t   act,
        int                                             flavor,
        thread_state_t                  state,                  /* pointer to OUT array */
        mach_msg_type_number_t  *state_count)   /*IN/OUT*/
{
        kern_return_t           result = KERN_SUCCESS;
        thread_t                        thread;

        if (act == THR_ACT_NULL || act == current_act())
                return (KERN_INVALID_ARGUMENT);

        thread = act_lock_thread(act);

        if (!act->active) {
                act_unlock_thread(act);
                return (KERN_TERMINATED);
        }

        thread_hold(act);

        for (;;) {
                thread_t                        thread1;

                if (    thread == THREAD_NULL           ||
                                thread->top_act != act          )
                        break;
                act_unlock_thread(act);

                if (!thread_stop(thread)) {
                        result = KERN_ABORTED;
                        (void)act_lock_thread(act);
                        thread = THREAD_NULL;
                        break;
                }
                        
                thread1 = act_lock_thread(act);
                if (thread1 == thread)
                        break;

                thread_unstop(thread);
                thread = thread1;
        }

        if (result == KERN_SUCCESS)
                result = act_machine_get_state(act, flavor, state, state_count);

        if (    thread != THREAD_NULL           &&
                        thread->top_act == act          )
                thread_unstop(thread);

        thread_release(act);
        act_unlock_thread(act);

        return (result);
}

/*
 *      Change thread's machine-dependent state.  Called with nothing
 *      locked.  Returns same way.
 */
kern_return_t
thread_set_state(
        register thread_act_t   act,
        int                                             flavor,
        thread_state_t                  state,
        mach_msg_type_number_t  state_count)
{
        kern_return_t           result = KERN_SUCCESS;
        thread_t                        thread;

        if (act == THR_ACT_NULL || act == current_act())
                return (KERN_INVALID_ARGUMENT);

        thread = act_lock_thread(act);

        if (!act->active) {
                act_unlock_thread(act);
                return (KERN_TERMINATED);
        }

        thread_hold(act);

        for (;;) {
                thread_t                        thread1;

                if (    thread == THREAD_NULL           ||
                                thread->top_act != act          )
                        break;
                act_unlock_thread(act);

                if (!thread_stop(thread)) {
                        result = KERN_ABORTED;
                        (void)act_lock_thread(act);
                        thread = THREAD_NULL;
                        break;
                }

                thread1 = act_lock_thread(act);
                if (thread1 == thread)
                        break;

                thread_unstop(thread);
                thread = thread1;
        }

        if (result == KERN_SUCCESS)
                result = act_machine_set_state(act, flavor, state, state_count);

        if (    thread != THREAD_NULL           &&
                        thread->top_act == act          )
            thread_unstop(thread);

        thread_release(act);
        act_unlock_thread(act);

        return (result);
}

/*
 * Kernel-internal "thread" interfaces used outside this file:
 */

kern_return_t
thread_dup(
        register thread_act_t   target)
{
        kern_return_t           result = KERN_SUCCESS;
        thread_act_t            self = current_act();
        thread_t                        thread;

        if (target == THR_ACT_NULL || target == self)
                return (KERN_INVALID_ARGUMENT);

        thread = act_lock_thread(target);

        if (!target->active) {
                act_unlock_thread(target);
                return (KERN_TERMINATED);
        }

        thread_hold(target);

        for (;;) {
                thread_t                        thread1;

                if (    thread == THREAD_NULL           ||
                                thread->top_act != target       )
                        break;
                act_unlock_thread(target);

                if (!thread_stop(thread)) {
                        result = KERN_ABORTED;
                        (void)act_lock_thread(target);
                        thread = THREAD_NULL;
                        break;
                }

                thread1 = act_lock_thread(target);
                if (thread1 == thread)
                        break;

                thread_unstop(thread);
                thread = thread1;
        }

        if (result == KERN_SUCCESS)
                result = act_thread_dup(self, target);

        if (    thread != THREAD_NULL           &&
                        thread->top_act == target       )
            thread_unstop(thread);

        thread_release(target);
        act_unlock_thread(target);

        return (result);
}


/*
 *      thread_setstatus:
 *
 *      Set the status of the specified thread.
 *      Called with (and returns with) no locks held.
 */
kern_return_t
thread_setstatus(
        register thread_act_t   act,
        int                                             flavor,
        thread_state_t                  tstate,
        mach_msg_type_number_t  count)
{
        kern_return_t           result = KERN_SUCCESS;
        thread_t                        thread;

        thread = act_lock_thread(act);

        if (    act != current_act()                    &&
                        (act->suspend_count == 0        ||
                         thread == THREAD_NULL          ||
                         (thread->state & TH_RUN)       ||
                         thread->top_act != act)                )
                result = KERN_FAILURE;

        if (result == KERN_SUCCESS)
                result = act_machine_set_state(act, flavor, tstate, count);

        act_unlock_thread(act);

        return (result);
}

/*
 *      thread_getstatus:
 *
 *      Get the status of the specified thread.
 */
kern_return_t
thread_getstatus(
        register thread_act_t   act,
        int                                             flavor,
        thread_state_t                  tstate,
        mach_msg_type_number_t  *count)
{
        kern_return_t           result = KERN_SUCCESS;
        thread_t                        thread;

        thread = act_lock_thread(act);

        if (    act != current_act()                    &&
                        (act->suspend_count == 0        ||
                         thread == THREAD_NULL          ||
                         (thread->state & TH_RUN)       ||
                         thread->top_act != act)                )
                result = KERN_FAILURE;

        if (result == KERN_SUCCESS)
                result = act_machine_get_state(act, flavor, tstate, count);

        act_unlock_thread(act);

        return (result);
}

/*
 * Kernel-internal thread_activation interfaces used outside this file:
 */

/*
 * act_init()   - Initialize activation handling code
 */
void
act_init()
{
        thr_act_zone = zinit(
                        sizeof(struct thread_activation),
                        ACT_MAX * sizeof(struct thread_activation), /* XXX */
                        ACT_CHUNK * sizeof(struct thread_activation),
                        "activations");
        first_act = TRUE;
        act_machine_init();
}


/*
 * act_create   - Create a new activation in a specific task.
 */
kern_return_t
act_create(task_t task,
           thread_act_t *new_act)
{
        thread_act_t thr_act;
        int rc;
        vm_map_t map;

        if (first_act) {
                thr_act = &pageout_act;
                first_act = FALSE;
        } else
                thr_act = (thread_act_t)zalloc(thr_act_zone);
        if (thr_act == 0)
                return(KERN_RESOURCE_SHORTAGE);

#if     MACH_ASSERT
        if (watchacts & WA_ACT_LNK)
                printf("act_create(task=%x,thr_act@%x=%x)\n",
                        task, new_act, thr_act);
#endif  /* MACH_ASSERT */

        /* Start by zeroing everything; then init non-zero items only */
        bzero((char *)thr_act, sizeof(*thr_act));

        if (thr_act == &pageout_act)
                thr_act->thread = &pageout_thread;

#ifdef MACH_BSD
        {
                /*
                 * Take care of the uthread allocation
                 * do it early in order to make KERN_RESOURCE_SHORTAGE
                 * handling trivial
                 * uthread_alloc() will bzero the storage allocated.
                 */
                extern void *uthread_alloc(task_t, thread_act_t);

                thr_act->uthread = uthread_alloc(task, thr_act);
                if(thr_act->uthread == 0) {
                        /* Put the thr_act back on the thr_act zone */
                        zfree(thr_act_zone, (vm_offset_t)thr_act);
                        return(KERN_RESOURCE_SHORTAGE);
                }
        }
#endif  /* MACH_BSD */

        /*
         * Start with one reference for the caller and one for the
         * act being alive.
         */
        act_lock_init(thr_act);
        thr_act->ref_count = 2;

        /* Latch onto the task.  */
        thr_act->task = task;
        task_reference(task);

        /* special_handler will always be last on the returnhandlers list.  */
        thr_act->special_handler.next = 0;
        thr_act->special_handler.handler = special_handler;

#if     MACH_PROF
        thr_act->act_profiled = FALSE;
        thr_act->act_profiled_own = FALSE;
        thr_act->profil_buffer = NULLPROFDATA;
#endif

        /* Initialize the held_ulocks queue as empty */
        queue_init(&thr_act->held_ulocks);

        /* Inherit the profiling status of the parent task */
        act_prof_init(thr_act, task);

        ipc_thr_act_init(task, thr_act);
        act_machine_create(task, thr_act);

        /*
         * If thr_act created in kernel-loaded task, alter its saved
         * state to so indicate
         */
        if (task->kernel_loaded) {
                act_user_to_kernel(thr_act);
        }

        /* Cache the task's map and take a reference to it */
        map = task->map;
        thr_act->map = map;

        /* Inline vm_map_reference cause we don't want to increment res_count */
        mutex_lock(&map->s_lock);
        map->ref_count++;
        mutex_unlock(&map->s_lock);

        *new_act = thr_act;
        return KERN_SUCCESS;
}

/*
 * act_free     - called when an thr_act's ref_count drops to zero.
 *
 * This can only happen after the activation has been reaped, and
 * all other references to it have gone away.  We can now release
 * the last critical resources, unlink the activation from the
 * task, and release the reference on the thread shuttle itself.
 *
 * Called with activation locked.
 */
#if     MACH_ASSERT
int     dangerous_bzero = 1;    /* paranoia & safety */
#endif

void
act_free(thread_act_t thr_act)
{
        task_t          task;
        thread_t        thr;
        vm_map_t        map;
        unsigned int    ref;
        void * task_proc;

#if     MACH_ASSERT
        if (watchacts & WA_EXIT)
                printf("act_free(%x(%d)) thr=%x tsk=%x(%d) %sactive\n",
                        thr_act, thr_act->ref_count, thr_act->thread,
                        thr_act->task,
                        thr_act->task ? thr_act->task->ref_count : 0,
                        thr_act->active ? " " : " !");
#endif  /* MACH_ASSERT */

        assert(!thr_act->active);

        task = thr_act->task;
        task_lock(task);

        task_proc = task->bsd_info;
        if (thr = thr_act->thread) {
                time_value_t    user_time, system_time;

                thread_read_times(thr, &user_time, &system_time);
                time_value_add(&task->total_user_time, &user_time);
                time_value_add(&task->total_system_time, &system_time);
        
                /* Unlink the thr_act from the task's thr_act list,
                 * so it doesn't appear in calls to task_threads and such.
                 * The thr_act still keeps its ref on the task, however.
                 */
                queue_remove(&task->thr_acts, thr_act, thread_act_t, thr_acts);
                thr_act->thr_acts.next = NULL;
                task->thr_act_count--;
                task->res_act_count--;
                task_unlock(task);
                task_deallocate(task);
                thread_deallocate(thr);
                act_machine_destroy(thr_act);
        } else {
                /*
                 * Must have never really gotten started
                 * no unlinking from the task and no need
                 * to free the shuttle.
                 */
                task_unlock(task);
                task_deallocate(task);
        }

        act_prof_deallocate(thr_act);
        ipc_thr_act_terminate(thr_act);

        /*
         * Drop the cached map reference.
         * Inline version of vm_map_deallocate() because we
         * don't want to decrement the map's residence count here.
         */
        map = thr_act->map;
        mutex_lock(&map->s_lock);
        ref = --map->ref_count;
        mutex_unlock(&map->s_lock);
        if (ref == 0)
                vm_map_destroy(map);

#ifdef MACH_BSD 
        {
                /*
                 * Free uthread BEFORE the bzero.
                 * Not doing so will result in a leak.
                 */
                extern void uthread_free(task_t, void *, void *);

                void *ut = thr_act->uthread;
                thr_act->uthread = 0;
                uthread_free(task, ut, task_proc);
        }
#endif  /* MACH_BSD */   

#if     MACH_ASSERT
        if (dangerous_bzero)    /* dangerous if we're still using it! */
                bzero((char *)thr_act, sizeof(*thr_act));
#endif  /* MACH_ASSERT */
        /* Put the thr_act back on the thr_act zone */
        zfree(thr_act_zone, (vm_offset_t)thr_act);
}


/*
 * act_attach   - Attach an thr_act to the top of a thread ("push the stack").
 *
 * The thread_shuttle must be either the current one or a brand-new one.
 * Assumes the thr_act is active but not in use.
 *
 * Already locked: thr_act plus "appropriate" thread-related locks
 * (see act_lock_thread()).
 */
void 
act_attach(
        thread_act_t    thr_act,
        thread_t        thread,
        unsigned        init_alert_mask)
{
        thread_act_t    lower;

#if     MACH_ASSERT
        assert(thread == current_thread() || thread->top_act == THR_ACT_NULL);
        if (watchacts & WA_ACT_LNK)
                printf("act_attach(thr_act %x(%d) thread %x(%d) mask %d)\n",
                       thr_act, thr_act->ref_count, thread, thread->ref_count,
                       init_alert_mask);
#endif  /* MACH_ASSERT */

        /* 
         *      Chain the thr_act onto the thread's thr_act stack.  
         *      Set mask and auto-propagate alerts from below.
         */
        thr_act->ref_count++;
        thr_act->thread = thread;
        thr_act->higher = THR_ACT_NULL;  /*safety*/
        thr_act->alerts = 0;
        thr_act->alert_mask = init_alert_mask;
        lower = thr_act->lower = thread->top_act;

        if (lower != THR_ACT_NULL) {
                lower->higher = thr_act;
                thr_act->alerts = (lower->alerts & init_alert_mask);
        }

        thread->top_act = thr_act;
}

/*
 *      act_detach      
 *
 *      Remove the current thr_act from the top of the current thread, i.e.
 *      "pop the stack". Assumes already locked: thr_act plus "appropriate"
 *      thread-related locks (see act_lock_thread).
 */
void 
act_detach(
        thread_act_t    cur_act)
{
        thread_t        cur_thread = cur_act->thread;

#if     MACH_ASSERT
        if (watchacts & (WA_EXIT|WA_ACT_LNK))
                printf("act_detach: thr_act %x(%d), thrd %x(%d) task=%x(%d)\n",
                       cur_act, cur_act->ref_count,
                       cur_thread, cur_thread->ref_count,
                       cur_act->task,
                       cur_act->task ? cur_act->task->ref_count : 0);
#endif  /* MACH_ASSERT */

        /* Unlink the thr_act from the thread's thr_act stack */
        cur_thread->top_act = cur_act->lower;
        cur_act->thread = 0;
        cur_act->ref_count--;
        assert(cur_act->ref_count > 0);

#if     MACH_ASSERT
        cur_act->lower = cur_act->higher = THR_ACT_NULL; 
        if (cur_thread->top_act)
                cur_thread->top_act->higher = THR_ACT_NULL;
#endif  /* MACH_ASSERT */

        return;
}


/*
 * Synchronize a thread operation with migration.
 * Called with nothing locked.
 * Returns with thr_act locked.
 */
thread_t
act_lock_thread(
        thread_act_t thr_act)
{

        /*
         * JMM - We have moved away from explicit RPC locks
         * and towards a generic migration approach.  The wait
         * queue lock will be the point of synchronization for
         * the shuttle linkage when this is rolled out.  Until
         * then, just lock the act.
         */
        act_lock(thr_act);
        return (thr_act->thread);
}

/*
 * Unsynchronize with migration (i.e., undo an act_lock_thread() call).
 * Called with thr_act locked, plus thread locks held that are
 * "correct" for thr_act's state.  Returns with nothing locked.
 */
void
act_unlock_thread(thread_act_t  thr_act)
{
        act_unlock(thr_act);
}

/*
 * Synchronize with migration given a pointer to a shuttle (instead of an
 * activation).  Called with nothing locked; returns with all
 * "appropriate" thread-related locks held (see act_lock_thread()).
 */
thread_act_t
thread_lock_act(
        thread_t        thread)
{
        thread_act_t    thr_act;

        while (1) {
                thr_act = thread->top_act;
                if (!thr_act)
                        break;
                if (!act_lock_try(thr_act)) {
                        mutex_pause();
                        continue;
                }
                break;
        }
        return (thr_act);
}

/*
 * Unsynchronize with an activation starting from a pointer to
 * a shuttle.
 */
void
thread_unlock_act(
        thread_t        thread)
{
        thread_act_t    thr_act;

        if (thr_act = thread->top_act) {
                act_unlock(thr_act);
        }
}

/*
 * switch_act
 *
 * If a new activation is given, switch to it. If not,
 * switch to the lower activation (pop). Returns the old
 * activation. This is for migration support.
 */
thread_act_t
switch_act( 
        thread_act_t act)
{
        thread_t        thread;
        thread_act_t    old, new;
        unsigned        cpu;
        spl_t           spl;


        disable_preemption();

        cpu = cpu_number();
        thread  = current_thread();

        /*
         *      Find the old and new activation for switch.
         */
        old = thread->top_act;

        if (act) {
                new = act;
                new->thread = thread;
        }
        else {
                new = old->lower;
        }

        assert(new != THR_ACT_NULL);
        assert(cpu_to_processor(cpu)->cpu_data->active_thread == thread);
        active_kloaded[cpu] = (new->kernel_loaded) ? new : 0;

        /* This is where all the work happens */
        machine_switch_act(thread, old, new, cpu);

        /*
         *      Push or pop an activation on the chain.
         */
        if (act) {
                act_attach(new, thread, 0);
        }
        else {
                act_detach(old);
        }

        enable_preemption();

        return(old);
}

/*
 * install_special_handler
 *      Install the special returnhandler that handles suspension and
 *      termination, if it hasn't been installed already.
 *
 * Already locked: RPC-related locks for thr_act, but not
 * scheduling lock (thread_lock()) of the associated thread.
 */
void
install_special_handler(
        thread_act_t    thr_act)
{
        spl_t           spl;
        thread_t        thread = thr_act->thread;

#if     MACH_ASSERT
        if (watchacts & WA_ACT_HDLR)
            printf("act_%x: install_special_hdlr(%x)\n",current_act(),thr_act);
#endif  /* MACH_ASSERT */

        spl = splsched();
        thread_lock(thread);
        install_special_handler_locked(thr_act);
        thread_unlock(thread);
        splx(spl);
}

/*
 * install_special_handler_locked
 *      Do the work of installing the special_handler.
 *
 * Already locked: RPC-related locks for thr_act, plus the
 * scheduling lock (thread_lock()) of the associated thread.
 */
void
install_special_handler_locked(
        thread_act_t                            act)
{
        thread_t                thread = act->thread;
        ReturnHandler   **rh;

        /* The work handler must always be the last ReturnHandler on the list,
           because it can do tricky things like detach the thr_act.  */
        for (rh = &act->handlers; *rh; rh = &(*rh)->next)
                continue;
        if (rh != &act->special_handler.next)
                *rh = &act->special_handler;

        if (act == thread->top_act) {
                /*
                 * Temporarily undepress, so target has
                 * a chance to do locking required to
                 * block itself in special_handler().
                 */
                if (thread->sched_mode & TH_MODE_ISDEPRESSED)
                        compute_priority(thread, TRUE);
        }

        thread_ast_set(act, AST_APC);
        if (act == current_act())
                ast_propagate(act->ast);
        else {
                processor_t             processor = thread->last_processor;

                if (    processor != PROCESSOR_NULL                                             &&
                                processor->state == PROCESSOR_RUNNING                   &&
                                processor->cpu_data->active_thread == thread    )
                        cause_ast_check(processor);
        }
}

kern_return_t
thread_apc_set(
        thread_act_t                    act,
        thread_apc_handler_t    apc)
{
        extern thread_apc_handler_t     bsd_ast;

        assert(apc == bsd_ast);
        return (KERN_FAILURE);
}

kern_return_t
thread_apc_clear(
        thread_act_t                    act,
        thread_apc_handler_t    apc)
{
        extern thread_apc_handler_t     bsd_ast;

        assert(apc == bsd_ast);
        return (KERN_FAILURE);
}

/*
 * Activation control support routines internal to this file:
 */

/*
 * act_execute_returnhandlers() - does just what the name says
 *
 * This is called by system-dependent code when it detects that
 * thr_act->handlers is non-null while returning into user mode.
 */
void
act_execute_returnhandlers(void)
{
        thread_act_t    act = current_act();

#if     MACH_ASSERT
        if (watchacts & WA_ACT_HDLR)
                printf("execute_rtn_hdlrs: act=%x\n", act);
#endif  /* MACH_ASSERT */

        thread_ast_clear(act, AST_APC);
        spllo();

        for (;;) {
                ReturnHandler   *rh;
                thread_t                thread = act_lock_thread(act);

                (void)splsched();
                thread_lock(thread);
                rh = act->handlers;
                if (!rh) {
                        thread_unlock(thread);
                        spllo();
                        act_unlock_thread(act);
                        return;
                }
                act->handlers = rh->next;
                thread_unlock(thread);
                spllo();
                act_unlock_thread(act);

#if     MACH_ASSERT
                if (watchacts & WA_ACT_HDLR)
                    printf( (rh == &act->special_handler) ?
                        "\tspecial_handler\n" : "\thandler=%x\n", rh->handler);
#endif  /* MACH_ASSERT */

                /* Execute it */
                (*rh->handler)(rh, act);
        }
}

/*
 * special_handler_continue
 *
 * Continuation routine for the special handler blocks.  It checks
 * to see whether there has been any new suspensions.  If so, it
 * installs the special handler again.  Otherwise, it checks to see
 * if the current depression needs to be re-instated (it may have
 * been temporarily removed in order to get to this point in a hurry).
 */
void
special_handler_continue(void)
{
        thread_act_t            self = current_act();

        if (self->suspend_count > 0)
                install_special_handler(self);
        else {
                thread_t                thread = self->thread;
                spl_t                   s = splsched();

                thread_lock(thread);
                if (thread->sched_mode & TH_MODE_ISDEPRESSED) {
                        processor_t             myprocessor = thread->last_processor;

                        thread->sched_pri = DEPRESSPRI;
                        myprocessor->current_pri = thread->sched_pri;
                        thread->sched_mode &= ~TH_MODE_PREEMPT;
                }
                thread_unlock(thread);
                splx(s);
        }

        thread_exception_return();
        /*NOTREACHED*/
}

/*
 * special_handler      - handles suspension, termination.  Called
 * with nothing locked.  Returns (if it returns) the same way.
 */
void
special_handler(
        ReturnHandler   *rh,
        thread_act_t    self)
{
        thread_t                thread = act_lock_thread(self);
        spl_t                   s;

        assert(thread != THREAD_NULL);

        s = splsched();
        thread_lock(thread);
        thread->state &= ~(TH_ABORT|TH_ABORT_SAFELY);   /* clear any aborts */
        thread_unlock(thread);
        splx(s);

        /*
         * If someone has killed this invocation,
         * invoke the return path with a terminated exception.
         */
        if (!self->active) {
                act_unlock_thread(self);
                act_machine_return(KERN_TERMINATED);
        }

        /*
         * If we're suspended, go to sleep and wait for someone to wake us up.
         */
        if (self->suspend_count > 0) {
                if (self->handlers == NULL) {
                        assert_wait(&self->suspend_count, THREAD_ABORTSAFE);
                        act_unlock_thread(self);
                        thread_block(special_handler_continue);
                        /* NOTREACHED */
                }

                act_unlock_thread(self);

                special_handler_continue();
                /*NOTREACHED*/
        }

        act_unlock_thread(self);
}

/*
 * Update activation that belongs to a task created via kernel_task_create().
 */
void
act_user_to_kernel(
        thread_act_t    thr_act)
{
        pcb_user_to_kernel(thr_act);
        thr_act->kernel_loading = TRUE;
}

/*
 * Already locked: activation (shuttle frozen within)
 *
 * Mark an activation inactive, and prepare it to terminate
 * itself.
 */
static void
act_disable(
        thread_act_t    thr_act)
{

#if     MACH_ASSERT
        if (watchacts & WA_EXIT) {
                printf("act_%x: act_disable_tl(thr_act=%x(%d))%sactive",
                               current_act(), thr_act, thr_act->ref_count,
                                        (thr_act->active ? " " : " !"));
                printf("\n");
                (void) dump_act(thr_act);
        }
#endif  /* MACH_ASSERT */

        thr_act->active = 0;

        /* Drop the thr_act reference taken for being active.
         * (There is still at least one reference left:
         * the one we were passed.)
         * Inline the deallocate because thr_act is locked.
         */
        act_locked_act_deallocate(thr_act);
}

/*
 * act_alert    - Register an alert from this activation.
 *
 * Each set bit is propagated upward from (but not including) this activation,
 * until the top of the chain is reached or the bit is masked.
 */
kern_return_t
act_alert(thread_act_t thr_act, unsigned alerts)
{
        thread_t thread = act_lock_thread(thr_act);

#if     MACH_ASSERT
        if (watchacts & WA_ACT_LNK)
                printf("act_alert %x: %x\n", thr_act, alerts);
#endif  /* MACH_ASSERT */

        if (thread) {
                thread_act_t act_up = thr_act;
                while ((alerts) && (act_up != thread->top_act)) {
                        act_up = act_up->higher;
                        alerts &= act_up->alert_mask;
                        act_up->alerts |= alerts;
                }
                /*
                 * XXXX If we reach the top, and it is blocked in glue
                 * code, do something to kick it.  XXXX
                 */
        }
        act_unlock_thread(thr_act);

        return KERN_SUCCESS;
}

kern_return_t act_alert_mask(thread_act_t thr_act, unsigned alert_mask)
{
        panic("act_alert_mask NOT YET IMPLEMENTED\n");
        return KERN_SUCCESS;
}

typedef struct GetSetState {
        struct ReturnHandler rh;
        int flavor;
        void *state;
        int *pcount;
        int result;
} GetSetState;

/* Local Forward decls */
kern_return_t get_set_state(
                        thread_act_t thr_act, int flavor,
                        thread_state_t state, int *pcount,
                        void (*handler)(ReturnHandler *rh, thread_act_t thr_act));
void get_state_handler(ReturnHandler *rh, thread_act_t thr_act);
void set_state_handler(ReturnHandler *rh, thread_act_t thr_act);

/*
 * get_set_state(thr_act ...)
 *
 * General code to install g/set_state handler.
 * Called with thr_act's act_lock() and "appropriate"
 * thread-related locks held.  (See act_lock_thread().)
 */
kern_return_t
get_set_state(
        thread_act_t            act,
        int                                     flavor,
        thread_state_t          state,
        int                                     *pcount,
        void                            (*handler)(
                                                        ReturnHandler   *rh,
                                                        thread_act_t     act))
{
        GetSetState                     gss;

        /* Initialize a small parameter structure */
        gss.rh.handler = handler;
        gss.flavor = flavor;
        gss.state = state;
        gss.pcount = pcount;
        gss.result = KERN_ABORTED;      /* iff wait below is interrupted */

        /* Add it to the thr_act's return handler list */
        gss.rh.next = act->handlers;
        act->handlers = &gss.rh;

        act_set_apc(act);

#if     MACH_ASSERT
        if (watchacts & WA_ACT_HDLR) {
            printf("act_%x: get_set_state(act=%x flv=%x state=%x ptr@%x=%x)",
                    current_act(), act, flavor, state,
                    pcount, (pcount ? *pcount : 0));
            printf((handler == get_state_handler ? "get_state_hdlr\n" :
                    (handler == set_state_handler ? "set_state_hdlr\n" :
                        "hndler=%x\n")), handler); 
        }
#endif  /* MACH_ASSERT */

        assert(act->thread);
        assert(act != current_act());

        for (;;) {
                wait_result_t           result;

                if (    act->inited                                             &&
                                act->thread->top_act == act             )
                                thread_wakeup_one(&act->suspend_count);

                /*
                 * Wait must be interruptible to avoid deadlock (e.g.) with
                 * task_suspend() when caller and target of get_set_state()
                 * are in same task.
                 */
                result = assert_wait(&gss, THREAD_ABORTSAFE);
                act_unlock_thread(act);

                if (result == THREAD_WAITING)
                        result = thread_block(THREAD_CONTINUE_NULL);

                assert(result != THREAD_WAITING);

                if (gss.result != KERN_ABORTED) {
                        assert(result != THREAD_INTERRUPTED);
                        break;
                }

                /* JMM - What about other aborts (like BSD signals)? */
                if (current_act()->handlers)
                        act_execute_returnhandlers();

                act_lock_thread(act);
        }

#if     MACH_ASSERT
        if (watchacts & WA_ACT_HDLR)
            printf("act_%x: get_set_state returns %x\n",
                            current_act(), gss.result);
#endif  /* MACH_ASSERT */

        return (gss.result);
}

void
set_state_handler(ReturnHandler *rh, thread_act_t thr_act)
{
        GetSetState *gss = (GetSetState*)rh;

#if     MACH_ASSERT
        if (watchacts & WA_ACT_HDLR)
                printf("act_%x: set_state_handler(rh=%x,thr_act=%x)\n",
                        current_act(), rh, thr_act);
#endif  /* MACH_ASSERT */

        gss->result = act_machine_set_state(thr_act, gss->flavor,
                                                gss->state, *gss->pcount);
        thread_wakeup((event_t)gss);
}

void
get_state_handler(ReturnHandler *rh, thread_act_t thr_act)
{
        GetSetState *gss = (GetSetState*)rh;

#if     MACH_ASSERT
        if (watchacts & WA_ACT_HDLR)
                printf("act_%x: get_state_handler(rh=%x,thr_act=%x)\n",
                        current_act(), rh, thr_act);
#endif  /* MACH_ASSERT */

        gss->result = act_machine_get_state(thr_act, gss->flavor,
                        gss->state, 
                        (mach_msg_type_number_t *) gss->pcount);
        thread_wakeup((event_t)gss);
}

kern_return_t
act_get_state_locked(thread_act_t thr_act, int flavor, thread_state_t state,
                                        mach_msg_type_number_t *pcount)
{
#if     MACH_ASSERT
    if (watchacts & WA_ACT_HDLR)
        printf("act_%x: act_get_state_L(thr_act=%x,flav=%x,st=%x,pcnt@%x=%x)\n",
                current_act(), thr_act, flavor, state, pcount,
                (pcount? *pcount : 0));
#endif  /* MACH_ASSERT */

    return(get_set_state(thr_act, flavor, state, (int*)pcount, get_state_handler));
}

kern_return_t
act_set_state_locked(thread_act_t thr_act, int flavor, thread_state_t state,
                                        mach_msg_type_number_t count)
{
#if     MACH_ASSERT
    if (watchacts & WA_ACT_HDLR)
        printf("act_%x: act_set_state_L(thr_act=%x,flav=%x,st=%x,pcnt@%x=%x)\n",
                current_act(), thr_act, flavor, state, count, count);
#endif  /* MACH_ASSERT */

    return(get_set_state(thr_act, flavor, state, (int*)&count, set_state_handler));
}

kern_return_t
act_set_state(thread_act_t thr_act, int flavor, thread_state_t state,
                                        mach_msg_type_number_t count)
{
    if (thr_act == THR_ACT_NULL || thr_act == current_act())
            return(KERN_INVALID_ARGUMENT);

    act_lock_thread(thr_act);
    return(act_set_state_locked(thr_act, flavor, state, count));
    
}

kern_return_t
act_get_state(thread_act_t thr_act, int flavor, thread_state_t state,
                                        mach_msg_type_number_t *pcount)
{
    if (thr_act == THR_ACT_NULL || thr_act == current_act())
            return(KERN_INVALID_ARGUMENT);

    act_lock_thread(thr_act);
    return(act_get_state_locked(thr_act, flavor, state, pcount));
}

void
act_set_astbsd(
        thread_act_t    act)
{
        spl_t                   s = splsched();
        
        if (act == current_act()) {
                thread_ast_set(act, AST_BSD);
                ast_propagate(act->ast);
        }
        else {
                thread_t                thread = act->thread;
                processor_t             processor;

                thread_lock(thread);
                thread_ast_set(act, AST_BSD);
                processor = thread->last_processor;
                if (    processor != PROCESSOR_NULL                                             &&
                                processor->state == PROCESSOR_RUNNING                   &&
                                processor->cpu_data->active_thread == thread    )
                        cause_ast_check(processor);
                thread_unlock(thread);
        }
        
        splx(s);
}

void
act_set_apc(
        thread_act_t    act)
{
        spl_t                   s = splsched();
        
        if (act == current_act()) {
                thread_ast_set(act, AST_APC);
                ast_propagate(act->ast);
        }
        else {
                thread_t                thread = act->thread;
                processor_t             processor;

                thread_lock(thread);
                thread_ast_set(act, AST_APC);
                processor = thread->last_processor;
                if (    processor != PROCESSOR_NULL                                             &&
                                processor->state == PROCESSOR_RUNNING                   &&
                                processor->cpu_data->active_thread == thread    )
                        cause_ast_check(processor);
                thread_unlock(thread);
        }
        
        splx(s);
}

void
act_ulock_release_all(thread_act_t thr_act)
{
        ulock_t ulock;

        while (!queue_empty(&thr_act->held_ulocks)) {
                ulock = (ulock_t) queue_first(&thr_act->held_ulocks);
                (void) lock_make_unstable(ulock, thr_act);
                (void) lock_release_internal(ulock, thr_act);
        }
}

/*
 * Provide routines (for export to other components) of things that
 * are implemented as macros insternally.
 */
thread_act_t
thread_self(void)
{
        thread_act_t self = current_act_fast();

        act_reference(self);
        return self;
}

thread_act_t
mach_thread_self(void)
{
        thread_act_t self = current_act_fast();

        act_reference(self);
        return self;
}

#undef act_reference
void
act_reference(
        thread_act_t thr_act)
{
        act_reference_fast(thr_act);
}

#undef act_deallocate
void
act_deallocate(
        thread_act_t thr_act) 
{
        act_deallocate_fast(thr_act);
}