common/disp/fx.c

	fx.c revision d5493db7e14e61d7910d92d1316d079110a327ef
/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */

/*
 * Copyright (c) 1994, 2010, Oracle and/or its affiliates. All rights reserved.
 */

#include <sys/types.h>
#include <sys/param.h>
#include <sys/sysmacros.h>
#include <sys/cred.h>
#include <sys/proc.h>
#include <sys/session.h>
#include <sys/strsubr.h>
#include <sys/user.h>
#include <sys/priocntl.h>
#include <sys/class.h>
#include <sys/disp.h>
#include <sys/procset.h>
#include <sys/debug.h>
#include <sys/kmem.h>
#include <sys/errno.h>
#include <sys/fx.h>
#include <sys/fxpriocntl.h>
#include <sys/cpuvar.h>
#include <sys/systm.h>
#include <sys/vtrace.h>
#include <sys/schedctl.h>
#include <sys/tnf_probe.h>
#include <sys/sunddi.h>
#include <sys/spl.h>
#include <sys/modctl.h>
#include <sys/policy.h>
#include <sys/sdt.h>
#include <sys/cpupart.h>
#include <sys/cpucaps.h>

static pri_t fx_init(id_t, int, classfuncs_t **);

static struct sclass csw = {
    "FX",
    fx_init,
    0
};

static struct modlsched modlsched = {
    &mod_schedops, "Fixed priority sched class", &csw
};

static struct modlinkage modlinkage = {
    MODREV_1, (void *)&modlsched, NULL
};


/*
 * control flags (kparms->fx_cflags).
 */
#define FX_DOUPRILIM    0x01    /* change user priority limit */
#define FX_DOUPRI   0x02    /* change user priority */
#define FX_DOTQ     0x04    /* change FX time quantum */


#define FXMAXUPRI 60        /* maximum user priority setting */

#define FX_MAX_UNPRIV_PRI   0   /* maximum unpriviledge priority */

/*
 * The fxproc_t structures that have a registered callback vector,
 * are also kept in an array of circular doubly linked lists. A hash on
 * the thread id (from ddi_get_kt_did()) is used to determine which list
 * each of such fxproc structures should be placed. Each list has a dummy
 * "head" which is never removed, so the list is never empty.
 */

#define FX_CB_LISTS 16      /* number of lists, must be power of 2 */
#define FX_CB_LIST_HASH(ktid)   ((uint_t)ktid & (FX_CB_LISTS - 1))

/* Insert fxproc into callback list */
#define FX_CB_LIST_INSERT(fxpp)                     \
{                                   \
    int index = FX_CB_LIST_HASH(fxpp->fx_ktid);         \
    kmutex_t *lockp = &fx_cb_list_lock[index];          \
    fxproc_t *headp = &fx_cb_plisthead[index];          \
    mutex_enter(lockp);                     \
    fxpp->fx_cb_next = headp->fx_cb_next;               \
    fxpp->fx_cb_prev = headp;                   \
    headp->fx_cb_next->fx_cb_prev = fxpp;               \
    headp->fx_cb_next = fxpp;                   \
    mutex_exit(lockp);                      \
}

/*
 * Remove thread from callback list.
 */
#define FX_CB_LIST_DELETE(fxpp)                     \
{                                   \
    int index = FX_CB_LIST_HASH(fxpp->fx_ktid);         \
    kmutex_t *lockp = &fx_cb_list_lock[index];          \
    mutex_enter(lockp);                     \
    fxpp->fx_cb_prev->fx_cb_next = fxpp->fx_cb_next;        \
    fxpp->fx_cb_next->fx_cb_prev = fxpp->fx_cb_prev;        \
    mutex_exit(lockp);                      \
}

#define FX_HAS_CB(fxpp) (fxpp->fx_callback != NULL)

/* adjust x to be between 0 and fx_maxumdpri */

#define FX_ADJUST_PRI(pri)                      \
{                                   \
    if (pri < 0)                            \
        pri = 0;                        \
    else if (pri > fx_maxumdpri)                    \
        pri = fx_maxumdpri;                     \
}

#define FX_ADJUST_QUANTUM(q)                        \
{                                   \
    if (q > INT_MAX)                        \
        q = INT_MAX;                        \
    else if (q <= 0)                        \
        q = FX_TQINF;                       \
}

#define FX_ISVALID(pri, quantum) \
    (((pri >= 0) || (pri == FX_CB_NOCHANGE)) &&         \
        ((quantum >= 0) || (quantum == FX_NOCHANGE) ||      \
        (quantum == FX_TQDEF) || (quantum == FX_TQINF)))


static id_t fx_cid;     /* fixed priority class ID */
static fxdpent_t *fx_dptbl; /* fixed priority disp parameter table */

static pri_t    fx_maxupri = FXMAXUPRI;
static pri_t    fx_maxumdpri;   /* max user mode fixed priority */

static pri_t    fx_maxglobpri;  /* maximum global priority used by fx class */
static kmutex_t fx_dptblock;    /* protects fixed priority dispatch table */


static kmutex_t fx_cb_list_lock[FX_CB_LISTS];   /* protects list of fxprocs */
                        /* that have callbacks */
static fxproc_t fx_cb_plisthead[FX_CB_LISTS];   /* dummy fxproc at head of */
                        /* list of fxprocs with */
                        /* callbacks */

static int  fx_admin(caddr_t, cred_t *);
static int  fx_getclinfo(void *);
static int  fx_parmsin(void *);
static int  fx_parmsout(void *, pc_vaparms_t *);
static int  fx_vaparmsin(void *, pc_vaparms_t *);
static int  fx_vaparmsout(void *, pc_vaparms_t *);
static int  fx_getclpri(pcpri_t *);
static int  fx_alloc(void **, int);
static void fx_free(void *);
static int  fx_enterclass(kthread_t *, id_t, void *, cred_t *, void *);
static void fx_exitclass(void *);
static int  fx_canexit(kthread_t *, cred_t *);
static int  fx_fork(kthread_t *, kthread_t *, void *);
static void fx_forkret(kthread_t *, kthread_t *);
static void fx_parmsget(kthread_t *, void *);
static int  fx_parmsset(kthread_t *, void *, id_t, cred_t *);
static void fx_stop(kthread_t *, int, int);
static void fx_exit(kthread_t *);
static pri_t    fx_swapin(kthread_t *, int);
static pri_t    fx_swapout(kthread_t *, int);
static void fx_trapret(kthread_t *);
static void fx_preempt(kthread_t *);
static void fx_setrun(kthread_t *);
static void fx_sleep(kthread_t *);
static void fx_tick(kthread_t *);
static void fx_wakeup(kthread_t *);
static int  fx_donice(kthread_t *, cred_t *, int, int *);
static int  fx_doprio(kthread_t *, cred_t *, int, int *);
static pri_t    fx_globpri(kthread_t *);
static void fx_yield(kthread_t *);
static void fx_nullsys();

extern fxdpent_t *fx_getdptbl(void);

static void fx_change_priority(kthread_t *, fxproc_t *);
static fxproc_t *fx_list_lookup(kt_did_t);
static void fx_list_release(fxproc_t *);


static struct classfuncs fx_classfuncs = {
    /* class functions */
    fx_admin,
    fx_getclinfo,
    fx_parmsin,
    fx_parmsout,
    fx_vaparmsin,
    fx_vaparmsout,
    fx_getclpri,
    fx_alloc,
    fx_free,

    /* thread functions */
    fx_enterclass,
    fx_exitclass,
    fx_canexit,
    fx_fork,
    fx_forkret,
    fx_parmsget,
    fx_parmsset,
    fx_stop,
    fx_exit,
    fx_nullsys, /* active */
    fx_nullsys, /* inactive */
    fx_swapin,
    fx_swapout,
    fx_trapret,
    fx_preempt,
    fx_setrun,
    fx_sleep,
    fx_tick,
    fx_wakeup,
    fx_donice,
    fx_globpri,
    fx_nullsys, /* set_process_group */
    fx_yield,
    fx_doprio,
};


int
_init()
{
    return (mod_install(&modlinkage));
}

int
_fini()
{
    return (EBUSY);
}

int
_info(struct modinfo *modinfop)
{
    return (mod_info(&modlinkage, modinfop));
}

/*
 * Fixed priority class initialization. Called by dispinit() at boot time.
 * We can ignore the clparmsz argument since we know that the smallest
 * possible parameter buffer is big enough for us.
 */
/* ARGSUSED */
static pri_t
fx_init(id_t cid, int clparmsz, classfuncs_t **clfuncspp)
{
    int i;
    extern pri_t fx_getmaxumdpri(void);

    fx_dptbl = fx_getdptbl();
    fx_maxumdpri = fx_getmaxumdpri();
    fx_maxglobpri = fx_dptbl[fx_maxumdpri].fx_globpri;

    fx_cid = cid;       /* Record our class ID */

    /*
     * Initialize the hash table for fxprocs with callbacks
     */
    for (i = 0; i < FX_CB_LISTS; i++) {
        fx_cb_plisthead[i].fx_cb_next = fx_cb_plisthead[i].fx_cb_prev =
            &fx_cb_plisthead[i];
    }

    /*
     * We're required to return a pointer to our classfuncs
     * structure and the highest global priority value we use.
     */
    *clfuncspp = &fx_classfuncs;
    return (fx_maxglobpri);
}

/*
 * Get or reset the fx_dptbl values per the user's request.
 */
static int
fx_admin(caddr_t uaddr, cred_t *reqpcredp)
{
    fxadmin_t   fxadmin;
    fxdpent_t   *tmpdpp;
    int     userdpsz;
    int     i;
    size_t      fxdpsz;

    if (get_udatamodel() == DATAMODEL_NATIVE) {
        if (copyin(uaddr, &fxadmin, sizeof (fxadmin_t)))
            return (EFAULT);
    }
#ifdef _SYSCALL32_IMPL
    else {
        /* get fxadmin struct from ILP32 caller */
        fxadmin32_t fxadmin32;
        if (copyin(uaddr, &fxadmin32, sizeof (fxadmin32_t)))
            return (EFAULT);
        fxadmin.fx_dpents =
            (struct fxdpent *)(uintptr_t)fxadmin32.fx_dpents;
        fxadmin.fx_ndpents = fxadmin32.fx_ndpents;
        fxadmin.fx_cmd = fxadmin32.fx_cmd;
    }
#endif /* _SYSCALL32_IMPL */

    fxdpsz = (fx_maxumdpri + 1) * sizeof (fxdpent_t);

    switch (fxadmin.fx_cmd) {
    case FX_GETDPSIZE:
        fxadmin.fx_ndpents = fx_maxumdpri + 1;

        if (get_udatamodel() == DATAMODEL_NATIVE) {
            if (copyout(&fxadmin, uaddr, sizeof (fxadmin_t)))
                return (EFAULT);
        }
#ifdef _SYSCALL32_IMPL
        else {
            /* return fxadmin struct to ILP32 caller */
            fxadmin32_t fxadmin32;
            fxadmin32.fx_dpents =
                (caddr32_t)(uintptr_t)fxadmin.fx_dpents;
            fxadmin32.fx_ndpents = fxadmin.fx_ndpents;
            fxadmin32.fx_cmd = fxadmin.fx_cmd;
            if (copyout(&fxadmin32, uaddr, sizeof (fxadmin32_t)))
                return (EFAULT);
        }
#endif /* _SYSCALL32_IMPL */
        break;

    case FX_GETDPTBL:
        userdpsz = MIN(fxadmin.fx_ndpents * sizeof (fxdpent_t),
            fxdpsz);
        if (copyout(fx_dptbl, fxadmin.fx_dpents, userdpsz))
            return (EFAULT);

        fxadmin.fx_ndpents = userdpsz / sizeof (fxdpent_t);

        if (get_udatamodel() == DATAMODEL_NATIVE) {
            if (copyout(&fxadmin, uaddr, sizeof (fxadmin_t)))
                return (EFAULT);
        }
#ifdef _SYSCALL32_IMPL
        else {
            /* return fxadmin struct to ILP32 callers */
            fxadmin32_t fxadmin32;
            fxadmin32.fx_dpents =
                (caddr32_t)(uintptr_t)fxadmin.fx_dpents;
            fxadmin32.fx_ndpents = fxadmin.fx_ndpents;
            fxadmin32.fx_cmd = fxadmin.fx_cmd;
            if (copyout(&fxadmin32, uaddr, sizeof (fxadmin32_t)))
                return (EFAULT);
        }
#endif /* _SYSCALL32_IMPL */
        break;

    case FX_SETDPTBL:
        /*
         * We require that the requesting process has sufficient
         * privileges. We also require that the table supplied by
         * the user exactly match the current fx_dptbl in size.
         */
        if (secpolicy_dispadm(reqpcredp) != 0) {
            return (EPERM);
        }
        if (fxadmin.fx_ndpents * sizeof (fxdpent_t) != fxdpsz) {
            return (EINVAL);
        }

        /*
         * We read the user supplied table into a temporary buffer
         * where it is validated before being copied over the
         * fx_dptbl.
         */
        tmpdpp = kmem_alloc(fxdpsz, KM_SLEEP);
        if (copyin(fxadmin.fx_dpents, tmpdpp, fxdpsz)) {
            kmem_free(tmpdpp, fxdpsz);
            return (EFAULT);
        }
        for (i = 0; i < fxadmin.fx_ndpents; i++) {

            /*
             * Validate the user supplied values. All we are doing
             * here is verifying that the values are within their
             * allowable ranges and will not panic the system. We
             * make no attempt to ensure that the resulting
             * configuration makes sense or results in reasonable
             * performance.
             */
            if (tmpdpp[i].fx_quantum <= 0 &&
                tmpdpp[i].fx_quantum != FX_TQINF) {
                kmem_free(tmpdpp, fxdpsz);
                return (EINVAL);
            }
        }

        /*
         * Copy the user supplied values over the current fx_dptbl
         * values. The fx_globpri member is read-only so we don't
         * overwrite it.
         */
        mutex_enter(&fx_dptblock);
        for (i = 0; i < fxadmin.fx_ndpents; i++) {
            fx_dptbl[i].fx_quantum = tmpdpp[i].fx_quantum;
        }
        mutex_exit(&fx_dptblock);
        kmem_free(tmpdpp, fxdpsz);
        break;

    default:
        return (EINVAL);
    }
    return (0);
}

/*
 * Allocate a fixed priority class specific thread structure and
 * initialize it with the parameters supplied. Also move the thread
 * to specified priority.
 */
static int
fx_enterclass(kthread_t *t, id_t cid, void *parmsp, cred_t *reqpcredp,
    void *bufp)
{
    fxkparms_t  *fxkparmsp = (fxkparms_t *)parmsp;
    fxproc_t    *fxpp;
    pri_t       reqfxupri;
    pri_t       reqfxuprilim;

    fxpp = (fxproc_t *)bufp;
    ASSERT(fxpp != NULL);

    /*
     * Initialize the fxproc structure.
     */
    fxpp->fx_flags = 0;
    fxpp->fx_callback = NULL;
    fxpp->fx_cookie = NULL;

    if (fxkparmsp == NULL) {
        /*
         * Use default values.
         */
        fxpp->fx_pri = fxpp->fx_uprilim = 0;
        fxpp->fx_pquantum = fx_dptbl[fxpp->fx_pri].fx_quantum;
        fxpp->fx_nice =  NZERO;
    } else {
        /*
         * Use supplied values.
         */

        if ((fxkparmsp->fx_cflags & FX_DOUPRILIM) == 0) {
            reqfxuprilim = 0;
        } else {
            if (fxkparmsp->fx_uprilim > FX_MAX_UNPRIV_PRI &&
                secpolicy_setpriority(reqpcredp) != 0)
                return (EPERM);
            reqfxuprilim = fxkparmsp->fx_uprilim;
            FX_ADJUST_PRI(reqfxuprilim);
        }

        if ((fxkparmsp->fx_cflags & FX_DOUPRI) == 0) {
            reqfxupri = reqfxuprilim;
        } else {
            if (fxkparmsp->fx_upri > FX_MAX_UNPRIV_PRI &&
                secpolicy_setpriority(reqpcredp) != 0)
                return (EPERM);
            /*
             * Set the user priority to the requested value
             * or the upri limit, whichever is lower.
             */
            reqfxupri = fxkparmsp->fx_upri;
            FX_ADJUST_PRI(reqfxupri);

            if (reqfxupri > reqfxuprilim)
                reqfxupri = reqfxuprilim;
        }


        fxpp->fx_uprilim = reqfxuprilim;
        fxpp->fx_pri = reqfxupri;

        fxpp->fx_nice = NZERO - (NZERO * reqfxupri) / fx_maxupri;

        if (((fxkparmsp->fx_cflags & FX_DOTQ) == 0) ||
            (fxkparmsp->fx_tqntm == FX_TQDEF)) {
            fxpp->fx_pquantum = fx_dptbl[fxpp->fx_pri].fx_quantum;
        } else {
            if (secpolicy_setpriority(reqpcredp) != 0)
                return (EPERM);

            if (fxkparmsp->fx_tqntm == FX_TQINF)
                fxpp->fx_pquantum = FX_TQINF;
            else {
                fxpp->fx_pquantum = fxkparmsp->fx_tqntm;
            }
        }

    }

    fxpp->fx_timeleft = fxpp->fx_pquantum;
    cpucaps_sc_init(&fxpp->fx_caps);
    fxpp->fx_tp = t;

    thread_lock(t);         /* get dispatcher lock on thread */
    t->t_clfuncs = &(sclass[cid].cl_funcs->thread);
    t->t_cid = cid;
    t->t_cldata = (void *)fxpp;
    t->t_schedflag &= ~TS_RUNQMATCH;
    fx_change_priority(t, fxpp);
    thread_unlock(t);

    return (0);
}

/*
 * The thread is exiting.
 */
static void
fx_exit(kthread_t *t)
{
    fxproc_t *fxpp;

    thread_lock(t);
    fxpp = (fxproc_t *)(t->t_cldata);

    /*
     * A thread could be exiting in between clock ticks, so we need to
     * calculate how much CPU time it used since it was charged last time.
     *
     * CPU caps are not enforced on exiting processes - it is usually
     * desirable to exit as soon as possible to free resources.
     */
    (void) CPUCAPS_CHARGE(t, &fxpp->fx_caps, CPUCAPS_CHARGE_ONLY);

    if (FX_HAS_CB(fxpp)) {
        FX_CB_EXIT(FX_CALLB(fxpp), fxpp->fx_cookie);
        fxpp->fx_callback = NULL;
        fxpp->fx_cookie = NULL;
        thread_unlock(t);
        FX_CB_LIST_DELETE(fxpp);
        return;
    }

    thread_unlock(t);
}

/*
 * Exiting the class. Free fxproc structure of thread.
 */
static void
fx_exitclass(void *procp)
{
    fxproc_t *fxpp = (fxproc_t *)procp;

    thread_lock(fxpp->fx_tp);
    if (FX_HAS_CB(fxpp)) {

        FX_CB_EXIT(FX_CALLB(fxpp), fxpp->fx_cookie);

        fxpp->fx_callback = NULL;
        fxpp->fx_cookie = NULL;
        thread_unlock(fxpp->fx_tp);
        FX_CB_LIST_DELETE(fxpp);
    } else
        thread_unlock(fxpp->fx_tp);

    kmem_free(fxpp, sizeof (fxproc_t));
}

/* ARGSUSED */
static int
fx_canexit(kthread_t *t, cred_t *cred)
{
    /*
     * A thread can always leave the FX class
     */
    return (0);
}

/*
 * Initialize fixed-priority class specific proc structure for a child.
 * callbacks are not inherited upon fork.
 */
static int
fx_fork(kthread_t *t, kthread_t *ct, void *bufp)
{
    fxproc_t    *pfxpp;     /* ptr to parent's fxproc structure */
    fxproc_t    *cfxpp;     /* ptr to child's fxproc structure */

    ASSERT(MUTEX_HELD(&ttoproc(t)->p_lock));

    cfxpp = (fxproc_t *)bufp;
    ASSERT(cfxpp != NULL);
    thread_lock(t);
    pfxpp = (fxproc_t *)t->t_cldata;
    /*
     * Initialize child's fxproc structure.
     */
    cfxpp->fx_timeleft = cfxpp->fx_pquantum = pfxpp->fx_pquantum;
    cfxpp->fx_pri = pfxpp->fx_pri;
    cfxpp->fx_uprilim = pfxpp->fx_uprilim;
    cfxpp->fx_nice = pfxpp->fx_nice;
    cfxpp->fx_callback = NULL;
    cfxpp->fx_cookie = NULL;
    cfxpp->fx_flags = pfxpp->fx_flags & ~(FXBACKQ);
    cpucaps_sc_init(&cfxpp->fx_caps);

    cfxpp->fx_tp = ct;
    ct->t_cldata = (void *)cfxpp;
    thread_unlock(t);

    /*
     * Link new structure into fxproc list.
     */
    return (0);
}


/*
 * Child is placed at back of dispatcher queue and parent gives
 * up processor so that the child runs first after the fork.
 * This allows the child immediately execing to break the multiple
 * use of copy on write pages with no disk home. The parent will
 * get to steal them back rather than uselessly copying them.
 */
static void
fx_forkret(kthread_t *t, kthread_t *ct)
{
    proc_t  *pp = ttoproc(t);
    proc_t  *cp = ttoproc(ct);
    fxproc_t *fxpp;

    ASSERT(t == curthread);
    ASSERT(MUTEX_HELD(&pidlock));

    /*
     * Grab the child's p_lock before dropping pidlock to ensure
     * the process does not disappear before we set it running.
     */
    mutex_enter(&cp->p_lock);
    continuelwps(cp);
    mutex_exit(&cp->p_lock);

    mutex_enter(&pp->p_lock);
    mutex_exit(&pidlock);
    continuelwps(pp);

    thread_lock(t);
    fxpp = (fxproc_t *)(t->t_cldata);
    t->t_pri = fx_dptbl[fxpp->fx_pri].fx_globpri;
    ASSERT(t->t_pri >= 0 && t->t_pri <= fx_maxglobpri);
    THREAD_TRANSITION(t);
    fx_setrun(t);
    thread_unlock(t);
    /*
     * Safe to drop p_lock now since it is safe to change
     * the scheduling class after this point.
     */
    mutex_exit(&pp->p_lock);

    swtch();
}


/*
 * Get information about the fixed-priority class into the buffer
 * pointed to by fxinfop. The maximum configured user priority
 * is the only information we supply.
 */
static int
fx_getclinfo(void *infop)
{
    fxinfo_t *fxinfop = (fxinfo_t *)infop;
    fxinfop->fx_maxupri = fx_maxupri;
    return (0);
}


/*
 * Return the user mode scheduling priority range.
 */
static int
fx_getclpri(pcpri_t *pcprip)
{
    pcprip->pc_clpmax = fx_maxupri;
    pcprip->pc_clpmin = 0;
    return (0);
}


static void
fx_nullsys()
{}


/*
 * Get the fixed-priority parameters of the thread pointed to by
 * fxprocp into the buffer pointed to by fxparmsp.
 */
static void
fx_parmsget(kthread_t *t, void *parmsp)
{
    fxproc_t *fxpp = (fxproc_t *)t->t_cldata;
    fxkparms_t *fxkparmsp = (fxkparms_t *)parmsp;

    fxkparmsp->fx_upri = fxpp->fx_pri;
    fxkparmsp->fx_uprilim = fxpp->fx_uprilim;
    fxkparmsp->fx_tqntm = fxpp->fx_pquantum;
}


/*
 * Check the validity of the fixed-priority parameters in the buffer
 * pointed to by fxparmsp.
 */
static int
fx_parmsin(void *parmsp)
{
    fxparms_t   *fxparmsp = (fxparms_t *)parmsp;
    uint_t      cflags;
    longlong_t  ticks;
    /*
     * Check validity of parameters.
     */

    if ((fxparmsp->fx_uprilim > fx_maxupri ||
        fxparmsp->fx_uprilim < 0) &&
        fxparmsp->fx_uprilim != FX_NOCHANGE)
        return (EINVAL);

    if ((fxparmsp->fx_upri > fx_maxupri ||
        fxparmsp->fx_upri < 0) &&
        fxparmsp->fx_upri != FX_NOCHANGE)
        return (EINVAL);

    if ((fxparmsp->fx_tqsecs == 0 && fxparmsp->fx_tqnsecs == 0) ||
        fxparmsp->fx_tqnsecs >= NANOSEC)
        return (EINVAL);

    cflags = (fxparmsp->fx_upri != FX_NOCHANGE ? FX_DOUPRI : 0);

    if (fxparmsp->fx_uprilim != FX_NOCHANGE) {
        cflags |= FX_DOUPRILIM;
    }

    if (fxparmsp->fx_tqnsecs != FX_NOCHANGE)
        cflags |= FX_DOTQ;

    /*
     * convert the buffer to kernel format.
     */

    if (fxparmsp->fx_tqnsecs >= 0) {
        if ((ticks = SEC_TO_TICK((longlong_t)fxparmsp->fx_tqsecs) +
            NSEC_TO_TICK_ROUNDUP(fxparmsp->fx_tqnsecs)) > INT_MAX)
            return (ERANGE);

        ((fxkparms_t *)fxparmsp)->fx_tqntm = (int)ticks;
    } else {
        if ((fxparmsp->fx_tqnsecs != FX_NOCHANGE) &&
            (fxparmsp->fx_tqnsecs != FX_TQINF) &&
            (fxparmsp->fx_tqnsecs != FX_TQDEF))
            return (EINVAL);
        ((fxkparms_t *)fxparmsp)->fx_tqntm = fxparmsp->fx_tqnsecs;
    }

    ((fxkparms_t *)fxparmsp)->fx_cflags = cflags;

    return (0);
}


/*
 * Check the validity of the fixed-priority parameters in the pc_vaparms_t
 * structure vaparmsp and put them in the buffer pointed to by fxprmsp.
 * pc_vaparms_t contains (key, value) pairs of parameter.
 */
static int
fx_vaparmsin(void *prmsp, pc_vaparms_t *vaparmsp)
{
    uint_t      secs = 0;
    uint_t      cnt;
    int     nsecs = 0;
    int     priflag, secflag, nsecflag, limflag;
    longlong_t  ticks;
    fxkparms_t  *fxprmsp = (fxkparms_t *)prmsp;
    pc_vaparm_t *vpp = &vaparmsp->pc_parms[0];


    /*
     * First check the validity of parameters and convert them
     * from the user supplied format to the internal format.
     */
    priflag = secflag = nsecflag = limflag = 0;

    fxprmsp->fx_cflags = 0;

    if (vaparmsp->pc_vaparmscnt > PC_VAPARMCNT)
        return (EINVAL);

    for (cnt = 0; cnt < vaparmsp->pc_vaparmscnt; cnt++, vpp++) {

        switch (vpp->pc_key) {
        case FX_KY_UPRILIM:
            if (limflag++)
                return (EINVAL);
            fxprmsp->fx_cflags |= FX_DOUPRILIM;
            fxprmsp->fx_uprilim = (pri_t)vpp->pc_parm;
            if (fxprmsp->fx_uprilim > fx_maxupri ||
                fxprmsp->fx_uprilim < 0)
                return (EINVAL);
            break;

        case FX_KY_UPRI:
            if (priflag++)
                return (EINVAL);
            fxprmsp->fx_cflags |= FX_DOUPRI;
            fxprmsp->fx_upri = (pri_t)vpp->pc_parm;
            if (fxprmsp->fx_upri > fx_maxupri ||
                fxprmsp->fx_upri < 0)
                return (EINVAL);
            break;

        case FX_KY_TQSECS:
            if (secflag++)
                return (EINVAL);
            fxprmsp->fx_cflags |= FX_DOTQ;
            secs = (uint_t)vpp->pc_parm;
            break;

        case FX_KY_TQNSECS:
            if (nsecflag++)
                return (EINVAL);
            fxprmsp->fx_cflags |= FX_DOTQ;
            nsecs = (int)vpp->pc_parm;
            break;

        default:
            return (EINVAL);
        }
    }

    if (vaparmsp->pc_vaparmscnt == 0) {
        /*
         * Use default parameters.
         */
        fxprmsp->fx_upri = 0;
        fxprmsp->fx_uprilim = 0;
        fxprmsp->fx_tqntm = FX_TQDEF;
        fxprmsp->fx_cflags = FX_DOUPRI | FX_DOUPRILIM | FX_DOTQ;
    } else if ((fxprmsp->fx_cflags & FX_DOTQ) != 0) {
        if ((secs == 0 && nsecs == 0) || nsecs >= NANOSEC)
            return (EINVAL);

        if (nsecs >= 0) {
            if ((ticks = SEC_TO_TICK((longlong_t)secs) +
                NSEC_TO_TICK_ROUNDUP(nsecs)) > INT_MAX)
                return (ERANGE);

            fxprmsp->fx_tqntm = (int)ticks;
        } else {
            if (nsecs != FX_TQINF && nsecs != FX_TQDEF)
                return (EINVAL);
            fxprmsp->fx_tqntm = nsecs;
        }
    }

    return (0);
}


/*
 * Nothing to do here but return success.
 */
/* ARGSUSED */
static int
fx_parmsout(void *parmsp, pc_vaparms_t *vaparmsp)
{
    register fxkparms_t *fxkprmsp = (fxkparms_t *)parmsp;

    if (vaparmsp != NULL)
        return (0);

    if (fxkprmsp->fx_tqntm < 0) {
        /*
         * Quantum field set to special value (e.g. FX_TQINF)
         */
        ((fxparms_t *)fxkprmsp)->fx_tqnsecs = fxkprmsp->fx_tqntm;
        ((fxparms_t *)fxkprmsp)->fx_tqsecs = 0;

    } else {
        /* Convert quantum from ticks to seconds-nanoseconds */

        timestruc_t ts;
        TICK_TO_TIMESTRUC(fxkprmsp->fx_tqntm, &ts);
        ((fxparms_t *)fxkprmsp)->fx_tqsecs = ts.tv_sec;
        ((fxparms_t *)fxkprmsp)->fx_tqnsecs = ts.tv_nsec;
    }

    return (0);
}


/*
 * Copy all selected fixed-priority class parameters to the user.
 * The parameters are specified by a key.
 */
static int
fx_vaparmsout(void *prmsp, pc_vaparms_t *vaparmsp)
{
    fxkparms_t  *fxkprmsp = (fxkparms_t *)prmsp;
    timestruc_t ts;
    uint_t      cnt;
    uint_t      secs;
    int     nsecs;
    int     priflag, secflag, nsecflag, limflag;
    pc_vaparm_t *vpp = &vaparmsp->pc_parms[0];

    ASSERT(MUTEX_NOT_HELD(&curproc->p_lock));

    priflag = secflag = nsecflag = limflag = 0;

    if (vaparmsp->pc_vaparmscnt > PC_VAPARMCNT)
        return (EINVAL);

    if (fxkprmsp->fx_tqntm < 0) {
        /*
         * Quantum field set to special value (e.g. FX_TQINF).
         */
        secs = 0;
        nsecs = fxkprmsp->fx_tqntm;
    } else {
        /*
         * Convert quantum from ticks to seconds-nanoseconds.
         */
        TICK_TO_TIMESTRUC(fxkprmsp->fx_tqntm, &ts);
        secs = ts.tv_sec;
        nsecs = ts.tv_nsec;
    }


    for (cnt = 0; cnt < vaparmsp->pc_vaparmscnt; cnt++, vpp++) {

        switch (vpp->pc_key) {
        case FX_KY_UPRILIM:
            if (limflag++)
                return (EINVAL);
            if (copyout(&fxkprmsp->fx_uprilim,
                (void *)(uintptr_t)vpp->pc_parm, sizeof (pri_t)))
                return (EFAULT);
            break;

        case FX_KY_UPRI:
            if (priflag++)
                return (EINVAL);
            if (copyout(&fxkprmsp->fx_upri,
                (void *)(uintptr_t)vpp->pc_parm, sizeof (pri_t)))
                return (EFAULT);
            break;

        case FX_KY_TQSECS:
            if (secflag++)
                return (EINVAL);
            if (copyout(&secs,
                (void *)(uintptr_t)vpp->pc_parm, sizeof (uint_t)))
                return (EFAULT);
            break;

        case FX_KY_TQNSECS:
            if (nsecflag++)
                return (EINVAL);
            if (copyout(&nsecs,
                (void *)(uintptr_t)vpp->pc_parm, sizeof (int)))
                return (EFAULT);
            break;

        default:
            return (EINVAL);
        }
    }

    return (0);
}

/*
 * Set the scheduling parameters of the thread pointed to by fxprocp
 * to those specified in the buffer pointed to by fxparmsp.
 */
/* ARGSUSED */
static int
fx_parmsset(kthread_t *tx, void *parmsp, id_t reqpcid, cred_t *reqpcredp)
{
    char        nice;
    pri_t       reqfxuprilim;
    pri_t       reqfxupri;
    fxkparms_t  *fxkparmsp = (fxkparms_t *)parmsp;
    fxproc_t    *fxpp;


    ASSERT(MUTEX_HELD(&(ttoproc(tx))->p_lock));

    thread_lock(tx);
    fxpp = (fxproc_t *)tx->t_cldata;

    if ((fxkparmsp->fx_cflags & FX_DOUPRILIM) == 0)
        reqfxuprilim = fxpp->fx_uprilim;
    else
        reqfxuprilim = fxkparmsp->fx_uprilim;

    /*
     * Basic permissions enforced by generic kernel code
     * for all classes require that a thread attempting
     * to change the scheduling parameters of a target
     * thread be privileged or have a real or effective
     * UID matching that of the target thread. We are not
     * called unless these basic permission checks have
     * already passed. The fixed priority class requires in
     * addition that the calling thread be privileged if it
     * is attempting to raise the pri above its current
     * value This may have been checked previously but if our
     * caller passed us a non-NULL credential pointer we assume
     * it hasn't and we check it here.
     */

    if ((reqpcredp != NULL) &&
        (reqfxuprilim > fxpp->fx_uprilim ||
        ((fxkparmsp->fx_cflags & FX_DOTQ) != 0)) &&
        secpolicy_setpriority(reqpcredp) != 0) {
        thread_unlock(tx);
        return (EPERM);
    }

    FX_ADJUST_PRI(reqfxuprilim);

    if ((fxkparmsp->fx_cflags & FX_DOUPRI) == 0)
        reqfxupri = fxpp->fx_pri;
    else
        reqfxupri = fxkparmsp->fx_upri;


    /*
     * Make sure the user priority doesn't exceed the upri limit.
     */
    if (reqfxupri > reqfxuprilim)
        reqfxupri = reqfxuprilim;

    /*
     * Set fx_nice to the nice value corresponding to the user
     * priority we are setting.  Note that setting the nice field
     * of the parameter struct won't affect upri or nice.
     */

    nice = NZERO - (reqfxupri * NZERO) / fx_maxupri;

    if (nice > NZERO)
        nice = NZERO;

    fxpp->fx_uprilim = reqfxuprilim;
    fxpp->fx_pri = reqfxupri;

    if (fxkparmsp->fx_tqntm == FX_TQINF)
        fxpp->fx_pquantum = FX_TQINF;
    else if (fxkparmsp->fx_tqntm == FX_TQDEF)
        fxpp->fx_pquantum = fx_dptbl[fxpp->fx_pri].fx_quantum;
    else if ((fxkparmsp->fx_cflags & FX_DOTQ) != 0)
        fxpp->fx_pquantum = fxkparmsp->fx_tqntm;

    fxpp->fx_nice = nice;

    fx_change_priority(tx, fxpp);
    thread_unlock(tx);
    return (0);
}


/*
 * Return the global scheduling priority that would be assigned
 * to a thread entering the fixed-priority class with the fx_upri.
 */
static pri_t
fx_globpri(kthread_t *t)
{
    fxproc_t *fxpp;

    ASSERT(MUTEX_HELD(&ttoproc(t)->p_lock));

    fxpp = (fxproc_t *)t->t_cldata;
    return (fx_dptbl[fxpp->fx_pri].fx_globpri);

}

/*
 * Arrange for thread to be placed in appropriate location
 * on dispatcher queue.
 *
 * This is called with the current thread in TS_ONPROC and locked.
 */
static void
fx_preempt(kthread_t *t)
{
    fxproc_t    *fxpp = (fxproc_t *)(t->t_cldata);

    ASSERT(t == curthread);
    ASSERT(THREAD_LOCK_HELD(curthread));

    (void) CPUCAPS_CHARGE(t, &fxpp->fx_caps, CPUCAPS_CHARGE_ENFORCE);

    /*
     * Check to see if we're doing "preemption control" here.  If
     * we are, and if the user has requested that this thread not
     * be preempted, and if preemptions haven't been put off for
     * too long, let the preemption happen here but try to make
     * sure the thread is rescheduled as soon as possible.  We do
     * this by putting it on the front of the highest priority run
     * queue in the FX class.  If the preemption has been put off
     * for too long, clear the "nopreempt" bit and let the thread
     * be preempted.
     */
    if (t->t_schedctl && schedctl_get_nopreempt(t)) {
        if (fxpp->fx_pquantum == FX_TQINF ||
            fxpp->fx_timeleft > -SC_MAX_TICKS) {
            DTRACE_SCHED1(schedctl__nopreempt, kthread_t *, t);
            schedctl_set_yield(t, 1);
            setfrontdq(t);
            return;
        } else {
            schedctl_set_nopreempt(t, 0);
            DTRACE_SCHED1(schedctl__preempt, kthread_t *, t);
            TNF_PROBE_2(schedctl_preempt, "schedctl FX fx_preempt",
                /* CSTYLED */, tnf_pid, pid, ttoproc(t)->p_pid,
                tnf_lwpid, lwpid, t->t_tid);
            /*
             * Fall through and be preempted below.
             */
        }
    }

    if (FX_HAS_CB(fxpp)) {
        clock_t new_quantum =  (clock_t)fxpp->fx_pquantum;
        pri_t   newpri = fxpp->fx_pri;
        FX_CB_PREEMPT(FX_CALLB(fxpp), fxpp->fx_cookie,
            &new_quantum, &newpri);
        FX_ADJUST_QUANTUM(new_quantum);
        if ((int)new_quantum != fxpp->fx_pquantum) {
            fxpp->fx_pquantum = (int)new_quantum;
            fxpp->fx_timeleft = fxpp->fx_pquantum;
        }
        FX_ADJUST_PRI(newpri);
        fxpp->fx_pri = newpri;
        THREAD_CHANGE_PRI(t, fx_dptbl[fxpp->fx_pri].fx_globpri);
    }

    /*
     * This thread may be placed on wait queue by CPU Caps. In this case we
     * do not need to do anything until it is removed from the wait queue.
     */
    if (CPUCAPS_ENFORCE(t)) {
        return;
    }

    if ((fxpp->fx_flags & (FXBACKQ)) == FXBACKQ) {
        fxpp->fx_timeleft = fxpp->fx_pquantum;
        fxpp->fx_flags &= ~FXBACKQ;
        setbackdq(t);
    } else {
        setfrontdq(t);
    }
}

static void
fx_setrun(kthread_t *t)
{
    fxproc_t *fxpp = (fxproc_t *)(t->t_cldata);

    ASSERT(THREAD_LOCK_HELD(t));    /* t should be in transition */
    fxpp->fx_flags &= ~FXBACKQ;

    if (t->t_disp_time != ddi_get_lbolt())
        setbackdq(t);
    else
        setfrontdq(t);
}


/*
 * Prepare thread for sleep. We reset the thread priority so it will
 * run at the kernel priority level when it wakes up.
 */
static void
fx_sleep(kthread_t *t)
{
    fxproc_t    *fxpp = (fxproc_t *)(t->t_cldata);

    ASSERT(t == curthread);
    ASSERT(THREAD_LOCK_HELD(t));

    /*
     * Account for time spent on CPU before going to sleep.
     */
    (void) CPUCAPS_CHARGE(t, &fxpp->fx_caps, CPUCAPS_CHARGE_ENFORCE);

    if (FX_HAS_CB(fxpp)) {
        FX_CB_SLEEP(FX_CALLB(fxpp), fxpp->fx_cookie);
    }
    t->t_stime = ddi_get_lbolt();       /* time stamp for the swapper */
}


/*
 * Return Values:
 *
 *  -1 if the thread is loaded or is not eligible to be swapped in.
 *
 * FX and RT threads are designed so that they don't swapout; however,
 * it is possible that while the thread is swapped out and in another class, it
 * can be changed to FX or RT.  Since these threads should be swapped in
 * as soon as they're runnable, rt_swapin returns SHRT_MAX, and fx_swapin
 * returns SHRT_MAX - 1, so that it gives deference to any swapped out
 * RT threads.
 */
/* ARGSUSED */
static pri_t
fx_swapin(kthread_t *t, int flags)
{
    pri_t   tpri = -1;

    ASSERT(THREAD_LOCK_HELD(t));

    if (t->t_state == TS_RUN && (t->t_schedflag & TS_LOAD) == 0) {
        tpri = (pri_t)SHRT_MAX - 1;
    }

    return (tpri);
}

/*
 * Return Values
 *  -1 if the thread isn't loaded or is not eligible to be swapped out.
 */
/* ARGSUSED */
static pri_t
fx_swapout(kthread_t *t, int flags)
{
    ASSERT(THREAD_LOCK_HELD(t));

    return (-1);

}

/* ARGSUSED */
static void
fx_stop(kthread_t *t, int why, int what)
{
    fxproc_t *fxpp = (fxproc_t *)(t->t_cldata);

    ASSERT(THREAD_LOCK_HELD(t));

    if (FX_HAS_CB(fxpp)) {
        FX_CB_STOP(FX_CALLB(fxpp), fxpp->fx_cookie);
    }
}

/*
 * Check for time slice expiration.  If time slice has expired
 * set runrun to cause preemption.
 */
static void
fx_tick(kthread_t *t)
{
    boolean_t call_cpu_surrender = B_FALSE;
    fxproc_t *fxpp;

    ASSERT(MUTEX_HELD(&(ttoproc(t))->p_lock));

    thread_lock(t);

    fxpp = (fxproc_t *)(t->t_cldata);

    if (FX_HAS_CB(fxpp)) {
        clock_t new_quantum =  (clock_t)fxpp->fx_pquantum;
        pri_t   newpri = fxpp->fx_pri;
        FX_CB_TICK(FX_CALLB(fxpp), fxpp->fx_cookie,
            &new_quantum, &newpri);
        FX_ADJUST_QUANTUM(new_quantum);
        if ((int)new_quantum != fxpp->fx_pquantum) {
            fxpp->fx_pquantum = (int)new_quantum;
            fxpp->fx_timeleft = fxpp->fx_pquantum;
        }
        FX_ADJUST_PRI(newpri);
        if (newpri != fxpp->fx_pri) {
            fxpp->fx_pri = newpri;
            fx_change_priority(t, fxpp);
        }
    }

    /*
     * Keep track of thread's project CPU usage.  Note that projects
     * get charged even when threads are running in the kernel.
     */
    call_cpu_surrender =  CPUCAPS_CHARGE(t, &fxpp->fx_caps,
        CPUCAPS_CHARGE_ENFORCE);

    if ((fxpp->fx_pquantum != FX_TQINF) &&
        (--fxpp->fx_timeleft <= 0)) {
        pri_t   new_pri;

        /*
         * If we're doing preemption control and trying to
         * avoid preempting this thread, just note that
         * the thread should yield soon and let it keep
         * running (unless it's been a while).
         */
        if (t->t_schedctl && schedctl_get_nopreempt(t)) {
            if (fxpp->fx_timeleft > -SC_MAX_TICKS) {
                DTRACE_SCHED1(schedctl__nopreempt,
                    kthread_t *, t);
                schedctl_set_yield(t, 1);
                thread_unlock_nopreempt(t);
                return;
            }
            TNF_PROBE_2(schedctl_failsafe,
                "schedctl FX fx_tick", /* CSTYLED */,
                tnf_pid, pid, ttoproc(t)->p_pid,
                tnf_lwpid, lwpid, t->t_tid);
        }
        new_pri = fx_dptbl[fxpp->fx_pri].fx_globpri;
        ASSERT(new_pri >= 0 && new_pri <= fx_maxglobpri);
        /*
         * When the priority of a thread is changed,
         * it may be necessary to adjust its position
         * on a sleep queue or dispatch queue. Even
         * when the priority is not changed, we need
         * to preserve round robin on dispatch queue.
         * The function thread_change_pri accomplishes
         * this.
         */
        if (thread_change_pri(t, new_pri, 0)) {
            fxpp->fx_timeleft = fxpp->fx_pquantum;
        } else {
            call_cpu_surrender = B_TRUE;
        }
    } else if (t->t_state == TS_ONPROC &&
        t->t_pri < t->t_disp_queue->disp_maxrunpri) {
        call_cpu_surrender = B_TRUE;
    }

    if (call_cpu_surrender) {
        fxpp->fx_flags |= FXBACKQ;
        cpu_surrender(t);
    }
    thread_unlock_nopreempt(t); /* clock thread can't be preempted */
}


static void
fx_trapret(kthread_t *t)
{
    cpu_t       *cp = CPU;

    ASSERT(THREAD_LOCK_HELD(t));
    ASSERT(t == curthread);
    ASSERT(cp->cpu_dispthread == t);
    ASSERT(t->t_state == TS_ONPROC);
}


/*
 * Processes waking up go to the back of their queue.
 */
static void
fx_wakeup(kthread_t *t)
{
    fxproc_t    *fxpp = (fxproc_t *)(t->t_cldata);

    ASSERT(THREAD_LOCK_HELD(t));

    t->t_stime = ddi_get_lbolt();       /* time stamp for the swapper */
    if (FX_HAS_CB(fxpp)) {
        clock_t new_quantum =  (clock_t)fxpp->fx_pquantum;
        pri_t   newpri = fxpp->fx_pri;
        FX_CB_WAKEUP(FX_CALLB(fxpp), fxpp->fx_cookie,
            &new_quantum, &newpri);
        FX_ADJUST_QUANTUM(new_quantum);
        if ((int)new_quantum != fxpp->fx_pquantum) {
            fxpp->fx_pquantum = (int)new_quantum;
            fxpp->fx_timeleft = fxpp->fx_pquantum;
        }

        FX_ADJUST_PRI(newpri);
        if (newpri != fxpp->fx_pri) {
            fxpp->fx_pri = newpri;
            THREAD_CHANGE_PRI(t, fx_dptbl[fxpp->fx_pri].fx_globpri);
        }
    }

    fxpp->fx_flags &= ~FXBACKQ;

    if (t->t_disp_time != ddi_get_lbolt())
        setbackdq(t);
    else
        setfrontdq(t);
}


/*
 * When a thread yields, put it on the back of the run queue.
 */
static void
fx_yield(kthread_t *t)
{
    fxproc_t    *fxpp = (fxproc_t *)(t->t_cldata);

    ASSERT(t == curthread);
    ASSERT(THREAD_LOCK_HELD(t));

    /*
     * Collect CPU usage spent before yielding CPU.
     */
    (void) CPUCAPS_CHARGE(t, &fxpp->fx_caps, CPUCAPS_CHARGE_ENFORCE);

    if (FX_HAS_CB(fxpp))  {
        clock_t new_quantum =  (clock_t)fxpp->fx_pquantum;
        pri_t   newpri = fxpp->fx_pri;
        FX_CB_PREEMPT(FX_CALLB(fxpp), fxpp->fx_cookie,
            &new_quantum, &newpri);
        FX_ADJUST_QUANTUM(new_quantum);
        if ((int)new_quantum != fxpp->fx_pquantum) {
            fxpp->fx_pquantum = (int)new_quantum;
            fxpp->fx_timeleft = fxpp->fx_pquantum;
        }
        FX_ADJUST_PRI(newpri);
        fxpp->fx_pri = newpri;
        THREAD_CHANGE_PRI(t, fx_dptbl[fxpp->fx_pri].fx_globpri);
    }

    /*
     * Clear the preemption control "yield" bit since the user is
     * doing a yield.
     */
    if (t->t_schedctl)
        schedctl_set_yield(t, 0);

    if (fxpp->fx_timeleft <= 0) {
        /*
         * Time slice was artificially extended to avoid
         * preemption, so pretend we're preempting it now.
         */
        DTRACE_SCHED1(schedctl__yield, int, -fxpp->fx_timeleft);
        fxpp->fx_timeleft = fxpp->fx_pquantum;
        THREAD_CHANGE_PRI(t, fx_dptbl[fxpp->fx_pri].fx_globpri);
        ASSERT(t->t_pri >= 0 && t->t_pri <= fx_maxglobpri);
    }

    fxpp->fx_flags &= ~FXBACKQ;
    setbackdq(t);
}

/*
 * Increment the nice value of the specified thread by incr and
 * return the new value in *retvalp.
 */
static int
fx_donice(kthread_t *t, cred_t *cr, int incr, int *retvalp)
{
    int     newnice;
    fxproc_t    *fxpp = (fxproc_t *)(t->t_cldata);
    fxkparms_t  fxkparms;

    ASSERT(MUTEX_HELD(&(ttoproc(t))->p_lock));

    /* If there's no change to priority, just return current setting */
    if (incr == 0) {
        if (retvalp) {
            *retvalp = fxpp->fx_nice - NZERO;
        }
        return (0);
    }

    if ((incr < 0 || incr > 2 * NZERO) &&
        secpolicy_setpriority(cr) != 0)
        return (EPERM);

    /*
     * Specifying a nice increment greater than the upper limit of
     * 2 * NZERO - 1 will result in the thread's nice value being
     * set to the upper limit.  We check for this before computing
     * the new value because otherwise we could get overflow
     * if a privileged user specified some ridiculous increment.
     */
    if (incr > 2 * NZERO - 1)
        incr = 2 * NZERO - 1;

    newnice = fxpp->fx_nice + incr;
    if (newnice > NZERO)
        newnice = NZERO;
    else if (newnice < 0)
        newnice = 0;

    fxkparms.fx_uprilim = fxkparms.fx_upri =
        -((newnice - NZERO) * fx_maxupri) / NZERO;

    fxkparms.fx_cflags = FX_DOUPRILIM | FX_DOUPRI;

    fxkparms.fx_tqntm = FX_TQDEF;

    /*
     * Reset the uprilim and upri values of the thread. Adjust
     * time quantum accordingly.
     */

    (void) fx_parmsset(t, (void *)&fxkparms, (id_t)0, (cred_t *)NULL);

    /*
     * Although fx_parmsset already reset fx_nice it may
     * not have been set to precisely the value calculated above
     * because fx_parmsset determines the nice value from the
     * user priority and we may have truncated during the integer
     * conversion from nice value to user priority and back.
     * We reset fx_nice to the value we calculated above.
     */
    fxpp->fx_nice = (char)newnice;

    if (retvalp)
        *retvalp = newnice - NZERO;

    return (0);
}

/*
 * Increment the priority of the specified thread by incr and
 * return the new value in *retvalp.
 */
static int
fx_doprio(kthread_t *t, cred_t *cr, int incr, int *retvalp)
{
    int     newpri;
    fxproc_t    *fxpp = (fxproc_t *)(t->t_cldata);
    fxkparms_t  fxkparms;

    ASSERT(MUTEX_HELD(&(ttoproc(t))->p_lock));

    /* If there's no change to priority, just return current setting */
    if (incr == 0) {
        *retvalp = fxpp->fx_pri;
        return (0);
    }

    newpri = fxpp->fx_pri + incr;
    if (newpri > fx_maxupri || newpri < 0)
        return (EINVAL);

    *retvalp = newpri;
    fxkparms.fx_uprilim = fxkparms.fx_upri = newpri;
    fxkparms.fx_tqntm = FX_NOCHANGE;
    fxkparms.fx_cflags = FX_DOUPRILIM | FX_DOUPRI;

    /*
     * Reset the uprilim and upri values of the thread.
     */
    return (fx_parmsset(t, (void *)&fxkparms, (id_t)0, cr));
}

static void
fx_change_priority(kthread_t *t, fxproc_t *fxpp)
{
    pri_t   new_pri;

    ASSERT(THREAD_LOCK_HELD(t));
    new_pri = fx_dptbl[fxpp->fx_pri].fx_globpri;
    ASSERT(new_pri >= 0 && new_pri <= fx_maxglobpri);
    t->t_cpri = fxpp->fx_pri;
    if (t == curthread || t->t_state == TS_ONPROC) {
        /* curthread is always onproc */
        cpu_t   *cp = t->t_disp_queue->disp_cpu;
        THREAD_CHANGE_PRI(t, new_pri);
        if (t == cp->cpu_dispthread)
            cp->cpu_dispatch_pri = DISP_PRIO(t);
        if (DISP_MUST_SURRENDER(t)) {
            fxpp->fx_flags |= FXBACKQ;
            cpu_surrender(t);
        } else {
            fxpp->fx_timeleft = fxpp->fx_pquantum;
        }
    } else {
        /*
         * When the priority of a thread is changed,
         * it may be necessary to adjust its position
         * on a sleep queue or dispatch queue.
         * The function thread_change_pri accomplishes
         * this.
         */
        if (thread_change_pri(t, new_pri, 0)) {
            /*
             * The thread was on a run queue. Reset
             * its CPU timeleft from the quantum
             * associated with the new priority.
             */
            fxpp->fx_timeleft = fxpp->fx_pquantum;
        } else {
            fxpp->fx_flags |= FXBACKQ;
        }
    }
}

static int
fx_alloc(void **p, int flag)
{
    void *bufp;

    bufp = kmem_alloc(sizeof (fxproc_t), flag);
    if (bufp == NULL) {
        return (ENOMEM);
    } else {
        *p = bufp;
        return (0);
    }
}

static void
fx_free(void *bufp)
{
    if (bufp)
        kmem_free(bufp, sizeof (fxproc_t));
}

/*
 * Release the callback list mutex after successful lookup
 */
void
fx_list_release(fxproc_t *fxpp)
{
    int index = FX_CB_LIST_HASH(fxpp->fx_ktid);
    kmutex_t *lockp = &fx_cb_list_lock[index];
    mutex_exit(lockp);
}

fxproc_t *
fx_list_lookup(kt_did_t ktid)
{
    int index = FX_CB_LIST_HASH(ktid);
    kmutex_t *lockp = &fx_cb_list_lock[index];
    fxproc_t *fxpp;

    mutex_enter(lockp);

    for (fxpp = fx_cb_plisthead[index].fx_cb_next;
        fxpp != &fx_cb_plisthead[index]; fxpp = fxpp->fx_cb_next) {
        if (fxpp->fx_tp->t_cid == fx_cid && fxpp->fx_ktid == ktid &&
            fxpp->fx_callback != NULL) {
            /*
             * The caller is responsible for calling
             * fx_list_release to drop the lock upon
             * successful lookup
             */
            return (fxpp);
        }
    }
    mutex_exit(lockp);
    return ((fxproc_t *)NULL);
}


/*
 * register a callback set of routines for current thread
 * thread should already be in FX class
 */
int
fx_register_callbacks(fx_callbacks_t *fx_callback, fx_cookie_t cookie,
    pri_t pri, clock_t quantum)
{

    fxproc_t    *fxpp;

    if (fx_callback == NULL)
        return (EINVAL);

    if (secpolicy_dispadm(CRED()) != 0)
        return (EPERM);

    if (FX_CB_VERSION(fx_callback) != FX_CALLB_REV)
        return (EINVAL);

    if (!FX_ISVALID(pri, quantum))
        return (EINVAL);

    thread_lock(curthread);     /* get dispatcher lock on thread */

    if (curthread->t_cid != fx_cid) {
        thread_unlock(curthread);
        return (EINVAL);
    }

    fxpp = (fxproc_t *)(curthread->t_cldata);
    ASSERT(fxpp != NULL);
    if (FX_HAS_CB(fxpp)) {
        thread_unlock(curthread);
        return (EINVAL);
    }

    fxpp->fx_callback = fx_callback;
    fxpp->fx_cookie = cookie;

    if (pri != FX_CB_NOCHANGE) {
        fxpp->fx_pri = pri;
        FX_ADJUST_PRI(fxpp->fx_pri);
        if (quantum == FX_TQDEF) {
            fxpp->fx_pquantum = fx_dptbl[fxpp->fx_pri].fx_quantum;
        } else if (quantum == FX_TQINF) {
            fxpp->fx_pquantum = FX_TQINF;
        } else if (quantum != FX_NOCHANGE) {
            FX_ADJUST_QUANTUM(quantum);
            fxpp->fx_pquantum = quantum;
        }
    } else if (quantum != FX_NOCHANGE && quantum != FX_TQDEF) {
        if (quantum == FX_TQINF)
            fxpp->fx_pquantum = FX_TQINF;
        else {
            FX_ADJUST_QUANTUM(quantum);
            fxpp->fx_pquantum = quantum;
        }
    }

    fxpp->fx_ktid = ddi_get_kt_did();

    fx_change_priority(curthread, fxpp);

    thread_unlock(curthread);

    /*
     * Link new structure into fxproc list.
     */
    FX_CB_LIST_INSERT(fxpp);
    return (0);
}

/* unregister a callback set of routines for current thread */
int
fx_unregister_callbacks()
{
    fxproc_t    *fxpp;

    if ((fxpp = fx_list_lookup(ddi_get_kt_did())) == NULL) {
        /*
         * did not have a registered callback;
         */
        return (EINVAL);
    }

    thread_lock(fxpp->fx_tp);
    fxpp->fx_callback = NULL;
    fxpp->fx_cookie = NULL;
    thread_unlock(fxpp->fx_tp);
    fx_list_release(fxpp);

    FX_CB_LIST_DELETE(fxpp);
    return (0);
}

/*
 * modify priority and/or quantum value of a thread with callback
 */
int
fx_modify_priority(kt_did_t ktid, clock_t quantum, pri_t pri)
{
    fxproc_t    *fxpp;

    if (!FX_ISVALID(pri, quantum))
        return (EINVAL);

    if ((fxpp = fx_list_lookup(ktid)) == NULL) {
        /*
         * either thread had exited or did not have a registered
         * callback;
         */
        return (ESRCH);
    }

    thread_lock(fxpp->fx_tp);

    if (pri != FX_CB_NOCHANGE) {
        fxpp->fx_pri = pri;
        FX_ADJUST_PRI(fxpp->fx_pri);
        if (quantum == FX_TQDEF) {
            fxpp->fx_pquantum = fx_dptbl[fxpp->fx_pri].fx_quantum;
        } else if (quantum == FX_TQINF) {
            fxpp->fx_pquantum = FX_TQINF;
        } else if (quantum != FX_NOCHANGE) {
            FX_ADJUST_QUANTUM(quantum);
            fxpp->fx_pquantum = quantum;
        }
    } else if (quantum != FX_NOCHANGE && quantum != FX_TQDEF) {
        if (quantum == FX_TQINF) {
            fxpp->fx_pquantum = FX_TQINF;
        } else {
            FX_ADJUST_QUANTUM(quantum);
            fxpp->fx_pquantum = quantum;
        }
    }

    fx_change_priority(fxpp->fx_tp, fxpp);

    thread_unlock(fxpp->fx_tp);
    fx_list_release(fxpp);
    return (0);
}


/*
 * return an iblock cookie for mutex initialization to be used in callbacks
 */
void *
fx_get_mutex_cookie()
{
    return ((void *)(uintptr_t)__ipltospl(DISP_LEVEL));
}

/*
 * return maximum relative priority
 */
pri_t
fx_get_maxpri()
{
    return (fx_maxumdpri);
}