common/disp/rt.c

	rt.c revision 7c478bd95313f5f23a4c958a745db2134aa03244
/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License, Version 1.0 only
 * (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 2005 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

/*  Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T */
/*    All Rights Reserved   */


#pragma ident   "%Z%%M% %I% %E% SMI"

#include <sys/types.h>
#include <sys/param.h>
#include <sys/sysmacros.h>
#include <sys/cred.h>
#include <sys/proc.h>
#include <sys/pcb.h>
#include <sys/signal.h>
#include <sys/user.h>
#include <sys/priocntl.h>
#include <sys/class.h>
#include <sys/disp.h>
#include <sys/procset.h>
#include <sys/cmn_err.h>
#include <sys/debug.h>
#include <sys/rt.h>
#include <sys/rtpriocntl.h>
#include <sys/kmem.h>
#include <sys/systm.h>
#include <sys/errno.h>
#include <sys/cpuvar.h>
#include <sys/vmsystm.h>
#include <sys/time.h>
#include <sys/policy.h>
#include <sys/sdt.h>
#include <sys/cpupart.h>
#include <sys/modctl.h>

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

static struct sclass csw = {
    "RT",
    rt_init,
    0
};

static struct modlsched modlsched = {
    &mod_schedops, "realtime scheduling class", &csw
};

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

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

int
_fini()
{
    return (EBUSY);     /* don't remove RT for now */
}

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


/*
 * Class specific code for the real-time class
 */

/*
 * Extern declarations for variables defined in the rt master file
 */
#define RTMAXPRI 59

pri_t rt_maxpri = RTMAXPRI; /* maximum real-time priority */
rtdpent_t *rt_dptbl;      /* real-time dispatcher parameter table */

/*
 * control flags (kparms->rt_cflags).
 */
#define RT_DOPRI    0x01    /* change priority */
#define RT_DOTQ     0x02    /* change RT time quantum */
#define RT_DOSIG    0x04    /* change RT time quantum signal */

static int  rt_admin(caddr_t, cred_t *);
static int  rt_enterclass(kthread_t *, id_t, void *, cred_t *, void *);
static int  rt_fork(kthread_t *, kthread_t *, void *);
static int  rt_getclinfo(void *);
static int  rt_getclpri(pcpri_t *);
static int  rt_parmsin(void *);
static int  rt_parmsout(void *, pc_vaparms_t *);
static int  rt_vaparmsin(void *, pc_vaparms_t *);
static int  rt_vaparmsout(void *, pc_vaparms_t *);
static int  rt_parmsset(kthread_t *, void *, id_t, cred_t *);
static int  rt_donice(kthread_t *, cred_t *, int, int *);
static void rt_exitclass(void *);
static int  rt_canexit(kthread_t *, cred_t *);
static void rt_forkret(kthread_t *, kthread_t *);
static void rt_nullsys();
static void rt_parmsget(kthread_t *, void *);
static void rt_preempt(kthread_t *);
static void rt_setrun(kthread_t *);
static void rt_tick(kthread_t *);
static void rt_wakeup(kthread_t *);
static pri_t    rt_swapin(kthread_t *, int);
static pri_t    rt_swapout(kthread_t *, int);
static pri_t    rt_globpri(kthread_t *);
static void rt_yield(kthread_t *);
static int  rt_alloc(void **, int);
static void rt_free(void *);

static void rt_change_priority(kthread_t *, rtproc_t *);

static id_t rt_cid;     /* real-time class ID */
static rtproc_t rt_plisthead;   /* dummy rtproc at head of rtproc list */
static kmutex_t rt_dptblock;    /* protects realtime dispatch table */
static kmutex_t rt_list_lock;   /* protects RT thread list */

extern rtdpent_t *rt_getdptbl(void);

static struct classfuncs rt_classfuncs = {
    /* class ops */
    rt_admin,
    rt_getclinfo,
    rt_parmsin,
    rt_parmsout,
    rt_vaparmsin,
    rt_vaparmsout,
    rt_getclpri,
    rt_alloc,
    rt_free,
    /* thread ops */
    rt_enterclass,
    rt_exitclass,
    rt_canexit,
    rt_fork,
    rt_forkret,
    rt_parmsget,
    rt_parmsset,
    rt_nullsys, /* stop */
    rt_nullsys, /* exit */
    rt_nullsys, /* active */
    rt_nullsys, /* inactive */
    rt_swapin,
    rt_swapout,
    rt_nullsys, /* trapret */
    rt_preempt,
    rt_setrun,
    rt_nullsys, /* sleep */
    rt_tick,
    rt_wakeup,
    rt_donice,
    rt_globpri,
    rt_nullsys, /* set_process_group */
    rt_yield,
};

/*
 * Real-time 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 */
pri_t
rt_init(id_t cid, int clparmsz, classfuncs_t **clfuncspp)
{
    rt_dptbl = rt_getdptbl();
    rt_cid = cid;   /* Record our class ID */

    /*
     * Initialize the rtproc list.
     */
    rt_plisthead.rt_next = rt_plisthead.rt_prev = &rt_plisthead;

    /*
     * We're required to return a pointer to our classfuncs
     * structure and the highest global priority value we use.
     */
    *clfuncspp = &rt_classfuncs;
    mutex_init(&rt_dptblock, NULL, MUTEX_DEFAULT, NULL);
    mutex_init(&rt_list_lock, NULL, MUTEX_DEFAULT, NULL);
    return (rt_dptbl[rt_maxpri].rt_globpri);
}

/*
 * Get or reset the rt_dptbl values per the user's request.
 */
/* ARGSUSED */
static int
rt_admin(caddr_t uaddr, cred_t *reqpcredp)
{
    rtadmin_t   rtadmin;
    rtdpent_t   *tmpdpp;
    size_t      userdpsz;
    size_t      rtdpsz;
    int     i;

    if (get_udatamodel() == DATAMODEL_NATIVE) {
        if (copyin(uaddr, &rtadmin, sizeof (rtadmin_t)))
            return (EFAULT);
    }
#ifdef _SYSCALL32_IMPL
    else {
        /* rtadmin struct from ILP32 callers */
        rtadmin32_t rtadmin32;
        if (copyin(uaddr, &rtadmin32, sizeof (rtadmin32_t)))
            return (EFAULT);
        rtadmin.rt_dpents =
            (struct rtdpent *)(uintptr_t)rtadmin32.rt_dpents;
        rtadmin.rt_ndpents = rtadmin32.rt_ndpents;
        rtadmin.rt_cmd = rtadmin32.rt_cmd;
    }
#endif /* _SYSCALL32_IMPL */

    rtdpsz = (rt_maxpri + 1) * sizeof (rtdpent_t);

    switch (rtadmin.rt_cmd) {

    case RT_GETDPSIZE:
        rtadmin.rt_ndpents = rt_maxpri + 1;

        if (get_udatamodel() == DATAMODEL_NATIVE) {
            if (copyout(&rtadmin, uaddr, sizeof (rtadmin_t)))
                return (EFAULT);
        }
#ifdef _SYSCALL32_IMPL
        else {
            /* return rtadmin struct to ILP32 callers */
            rtadmin32_t rtadmin32;
            rtadmin32.rt_dpents =
                (caddr32_t)(uintptr_t)rtadmin.rt_dpents;
            rtadmin32.rt_ndpents = rtadmin.rt_ndpents;
            rtadmin32.rt_cmd = rtadmin.rt_cmd;
            if (copyout(&rtadmin32, uaddr, sizeof (rtadmin32_t)))
                return (EFAULT);
        }
#endif /* _SYSCALL32_IMPL */

        break;

    case RT_GETDPTBL:
        userdpsz = MIN(rtadmin.rt_ndpents * sizeof (rtdpent_t),
            rtdpsz);
        if (copyout(rt_dptbl, rtadmin.rt_dpents, userdpsz))
            return (EFAULT);
        rtadmin.rt_ndpents = userdpsz / sizeof (rtdpent_t);

        if (get_udatamodel() == DATAMODEL_NATIVE) {
            if (copyout(&rtadmin, uaddr, sizeof (rtadmin_t)))
                return (EFAULT);
        }
#ifdef _SYSCALL32_IMPL
        else {
            /* return rtadmin struct to ILP32 callers */
            rtadmin32_t rtadmin32;
            rtadmin32.rt_dpents =
                (caddr32_t)(uintptr_t)rtadmin.rt_dpents;
            rtadmin32.rt_ndpents = rtadmin.rt_ndpents;
            rtadmin32.rt_cmd = rtadmin.rt_cmd;
            if (copyout(&rtadmin32, uaddr, sizeof (rtadmin32_t)))
                return (EFAULT);
        }
#endif /* _SYSCALL32_IMPL */
        break;

    case RT_SETDPTBL:
        /*
         * We require that the requesting process has sufficient
         * priveleges.  We also require that the table supplied by
         * the user exactly match the current rt_dptbl in size.
         */
        if (secpolicy_dispadm(reqpcredp) != 0)
            return (EPERM);
        if (rtadmin.rt_ndpents * sizeof (rtdpent_t) != rtdpsz)
            return (EINVAL);

        /*
         * We read the user supplied table into a temporary buffer
         * where the time quantum values are validated before
         * being copied to the rt_dptbl.
         */
        tmpdpp = kmem_alloc(rtdpsz, KM_SLEEP);
        if (copyin(rtadmin.rt_dpents, tmpdpp, rtdpsz)) {
            kmem_free(tmpdpp, rtdpsz);
            return (EFAULT);
        }
        for (i = 0; i < rtadmin.rt_ndpents; i++) {

            /*
             * Validate the user supplied time quantum values.
             */
            if (tmpdpp[i].rt_quantum <= 0 &&
                tmpdpp[i].rt_quantum != RT_TQINF) {
                kmem_free(tmpdpp, rtdpsz);
                return (EINVAL);
            }
        }

        /*
         * Copy the user supplied values over the current rt_dptbl
         * values.  The rt_globpri member is read-only so we don't
         * overwrite it.
         */
        mutex_enter(&rt_dptblock);
        for (i = 0; i < rtadmin.rt_ndpents; i++)
            rt_dptbl[i].rt_quantum = tmpdpp[i].rt_quantum;
        mutex_exit(&rt_dptblock);
        kmem_free(tmpdpp, rtdpsz);
        break;

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


/*
 * Allocate a real-time class specific proc structure and
 * initialize it with the parameters supplied. Also move thread
 * to specified real-time priority.
 */
/* ARGSUSED */
static int
rt_enterclass(kthread_t *t, id_t cid, void *parmsp, cred_t *reqpcredp,
    void *bufp)
{
    rtkparms_t *rtkparmsp = (rtkparms_t *)parmsp;
    rtproc_t *rtpp;

    /*
     * For a thread to enter the real-time class the thread
     * which initiates the request must be privileged.
     * This may have been checked previously but if our
     * caller passed us a credential structure we assume it
     * hasn't and we check it here.
     */
    if (reqpcredp != NULL && secpolicy_setpriority(reqpcredp) != 0)
        return (EPERM);

    rtpp = (rtproc_t *)bufp;
    ASSERT(rtpp != NULL);

    /*
     * If this thread's lwp is swapped out, it will be brought in
     * when it is put onto the runqueue.
     *
     * Now, Initialize the rtproc structure.
     */
    if (rtkparmsp == NULL) {
        /*
         * Use default values
         */
        rtpp->rt_pri = 0;
        rtpp->rt_pquantum = rt_dptbl[0].rt_quantum;
        rtpp->rt_tqsignal = 0;
    } else {
        /*
         * Use supplied values
         */
        if ((rtkparmsp->rt_cflags & RT_DOPRI) == 0)
            rtpp->rt_pri = 0;
        else
            rtpp->rt_pri = rtkparmsp->rt_pri;

        if (rtkparmsp->rt_tqntm == RT_TQINF)
            rtpp->rt_pquantum = RT_TQINF;
        else if (rtkparmsp->rt_tqntm == RT_TQDEF ||
            (rtkparmsp->rt_cflags & RT_DOTQ) == 0)
            rtpp->rt_pquantum = rt_dptbl[rtpp->rt_pri].rt_quantum;
        else
            rtpp->rt_pquantum = rtkparmsp->rt_tqntm;

        if ((rtkparmsp->rt_cflags & RT_DOSIG) == 0)
            rtpp->rt_tqsignal = 0;
        else
            rtpp->rt_tqsignal = rtkparmsp->rt_tqsig;
    }
    rtpp->rt_flags = 0;
    rtpp->rt_tp = t;
    /*
     * Reset thread priority
     */
    thread_lock(t);
    t->t_clfuncs = &(sclass[cid].cl_funcs->thread);
    t->t_cid = cid;
    t->t_cldata = (void *)rtpp;
    t->t_schedflag &= ~TS_RUNQMATCH;
    rt_change_priority(t, rtpp);
    thread_unlock(t);
    /*
     * Link new structure into rtproc list
     */
    mutex_enter(&rt_list_lock);
    rtpp->rt_next = rt_plisthead.rt_next;
    rtpp->rt_prev = &rt_plisthead;
    rt_plisthead.rt_next->rt_prev = rtpp;
    rt_plisthead.rt_next = rtpp;
    mutex_exit(&rt_list_lock);
    return (0);
}


/*
 * Free rtproc structure of thread.
 */
static void
rt_exitclass(void *procp)
{
    rtproc_t *rtprocp = (rtproc_t *)procp;

    mutex_enter(&rt_list_lock);
    rtprocp->rt_prev->rt_next = rtprocp->rt_next;
    rtprocp->rt_next->rt_prev = rtprocp->rt_prev;
    mutex_exit(&rt_list_lock);
    kmem_free(rtprocp, sizeof (rtproc_t));
}


/*
 * Allocate and initialize real-time class specific
 * proc structure for child.
 */
/* ARGSUSED */
static int
rt_fork(kthread_t *t, kthread_t *ct, void *bufp)
{
    rtproc_t *prtpp;
    rtproc_t *crtpp;

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

    /*
     * Initialize child's rtproc structure
     */
    crtpp = (rtproc_t *)bufp;
    ASSERT(crtpp != NULL);
    prtpp = (rtproc_t *)t->t_cldata;
    thread_lock(t);
    crtpp->rt_timeleft = crtpp->rt_pquantum = prtpp->rt_pquantum;
    crtpp->rt_pri = prtpp->rt_pri;
    crtpp->rt_flags = prtpp->rt_flags & ~RTBACKQ;
    crtpp->rt_tqsignal = prtpp->rt_tqsignal;

    crtpp->rt_tp = ct;
    thread_unlock(t);

    /*
     * Link new structure into rtproc list
     */
    ct->t_cldata = (void *)crtpp;
    mutex_enter(&rt_list_lock);
    crtpp->rt_next = rt_plisthead.rt_next;
    crtpp->rt_prev = &rt_plisthead;
    rt_plisthead.rt_next->rt_prev = crtpp;
    rt_plisthead.rt_next = crtpp;
    mutex_exit(&rt_list_lock);
    return (0);
}


/*
 * The child goes to the back of its dispatcher queue while the
 * parent continues to run after a real time thread forks.
 */
/* ARGSUSED */
static void
rt_forkret(kthread_t *t, kthread_t *ct)
{
    proc_t *pp = ttoproc(t);
    proc_t *cp = ttoproc(ct);

    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);
    mutex_exit(&pidlock);
    continuelwps(cp);
    mutex_exit(&cp->p_lock);

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


/*
 * Get information about the real-time class into the buffer
 * pointed to by rtinfop.  The maximum configured real-time
 * priority is the only information we supply.  We ignore the
 * class and credential arguments because anyone can have this
 * information.
 */
/* ARGSUSED */
static int
rt_getclinfo(void *infop)
{
    rtinfo_t *rtinfop = (rtinfo_t *)infop;
    rtinfop->rt_maxpri = rt_maxpri;
    return (0);
}

/*
 * Return the global scheduling priority ranges of the realtime
 * class in pcpri_t structure.
 */
static int
rt_getclpri(pcpri_t *pcprip)
{
    pcprip->pc_clpmax = rt_dptbl[rt_maxpri].rt_globpri;
    pcprip->pc_clpmin = rt_dptbl[0].rt_globpri;
    return (0);
}
static void
rt_nullsys()
{
}

/* ARGSUSED */
static int
rt_canexit(kthread_t *t, cred_t *cred)
{
    /*
     * Thread can always leave RT class
     */
    return (0);
}

/*
 * Get the real-time scheduling parameters of the thread pointed to by
 * rtprocp into the buffer pointed to by rtkparmsp.
 */
static void
rt_parmsget(kthread_t *t, void *parmsp)
{
    rtproc_t    *rtprocp = (rtproc_t *)t->t_cldata;
    rtkparms_t  *rtkparmsp = (rtkparms_t *)parmsp;

    rtkparmsp->rt_pri = rtprocp->rt_pri;
    rtkparmsp->rt_tqntm = rtprocp->rt_pquantum;
    rtkparmsp->rt_tqsig = rtprocp->rt_tqsignal;
}


/*
 * Check the validity of the real-time parameters in the buffer
 * pointed to by rtprmsp.
 * We convert the rtparms buffer from the user supplied format to
 * our internal format (i.e. time quantum expressed in ticks).
 */
static int
rt_parmsin(void *prmsp)
{
    rtparms_t *rtprmsp = (rtparms_t *)prmsp;
    longlong_t  ticks;
    uint_t      cflags;

    /*
     * First check the validity of parameters and convert
     * the buffer to kernel format.
     */
    if ((rtprmsp->rt_pri < 0 || rtprmsp->rt_pri > rt_maxpri) &&
        rtprmsp->rt_pri != RT_NOCHANGE)
        return (EINVAL);

    cflags = (rtprmsp->rt_pri != RT_NOCHANGE ? RT_DOPRI : 0);

    if ((rtprmsp->rt_tqsecs == 0 && rtprmsp->rt_tqnsecs == 0) ||
        rtprmsp->rt_tqnsecs >= NANOSEC)
        return (EINVAL);

    if (rtprmsp->rt_tqnsecs != RT_NOCHANGE)
        cflags |= RT_DOTQ;

    if (rtprmsp->rt_tqnsecs >= 0) {
        if ((ticks = SEC_TO_TICK((longlong_t)rtprmsp->rt_tqsecs) +
            NSEC_TO_TICK_ROUNDUP(rtprmsp->rt_tqnsecs)) > INT_MAX)
            return (ERANGE);

        ((rtkparms_t *)rtprmsp)->rt_tqntm = (int)ticks;
    } else {
        if (rtprmsp->rt_tqnsecs != RT_NOCHANGE &&
            rtprmsp->rt_tqnsecs != RT_TQINF &&
            rtprmsp->rt_tqnsecs != RT_TQDEF)
            return (EINVAL);

        ((rtkparms_t *)rtprmsp)->rt_tqntm = rtprmsp->rt_tqnsecs;
    }
    ((rtkparms_t *)rtprmsp)->rt_cflags = cflags;

    return (0);
}


/*
 * Check the validity of the real-time parameters in the pc_vaparms_t
 * structure vaparmsp and put them in the buffer pointed to by rtprmsp.
 * pc_vaparms_t contains (key, value) pairs of parameter.
 * rt_vaparmsin() is the variable parameter version of rt_parmsin().
 */
static int
rt_vaparmsin(void *prmsp, pc_vaparms_t *vaparmsp)
{
    uint_t      secs = 0;
    uint_t      cnt;
    int     nsecs = 0;
    int     priflag, secflag, nsecflag, sigflag;
    longlong_t  ticks;
    rtkparms_t  *rtprmsp = (rtkparms_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 = sigflag = 0;
    rtprmsp->rt_cflags = 0;

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

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

        switch (vpp->pc_key) {
        case RT_KY_PRI:
            if (priflag++)
                return (EINVAL);
            rtprmsp->rt_cflags |= RT_DOPRI;
            rtprmsp->rt_pri = (pri_t)vpp->pc_parm;
            if (rtprmsp->rt_pri < 0 || rtprmsp->rt_pri > rt_maxpri)
                return (EINVAL);
            break;

        case RT_KY_TQSECS:
            if (secflag++)
                return (EINVAL);
            rtprmsp->rt_cflags |= RT_DOTQ;
            secs = (uint_t)vpp->pc_parm;
            break;

        case RT_KY_TQNSECS:
            if (nsecflag++)
                return (EINVAL);
            rtprmsp->rt_cflags |= RT_DOTQ;
            nsecs = (int)vpp->pc_parm;
            break;

        case RT_KY_TQSIG:
            if (sigflag++)
                return (EINVAL);
            rtprmsp->rt_cflags |= RT_DOSIG;
            rtprmsp->rt_tqsig = (int)vpp->pc_parm;
            if (rtprmsp->rt_tqsig < 0 || rtprmsp->rt_tqsig >= NSIG)
                return (EINVAL);
            break;

        default:
            return (EINVAL);
        }
    }

    if (vaparmsp->pc_vaparmscnt == 0) {
        /*
         * Use default parameters.
         */
        rtprmsp->rt_pri = 0;
        rtprmsp->rt_tqntm = RT_TQDEF;
        rtprmsp->rt_tqsig = 0;
        rtprmsp->rt_cflags = RT_DOPRI | RT_DOTQ | RT_DOSIG;
    } else if ((rtprmsp->rt_cflags & RT_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);

            rtprmsp->rt_tqntm = (int)ticks;
        } else {
            if (nsecs != RT_TQINF && nsecs != RT_TQDEF)
                return (EINVAL);
            rtprmsp->rt_tqntm = nsecs;
        }
    }

    return (0);
}

/*
 * Do required processing on the real-time parameter buffer
 * before it is copied out to the user.
 * All we have to do is convert the buffer from kernel to user format
 * (i.e. convert time quantum from ticks to seconds-nanoseconds).
 */
/* ARGSUSED */
static int
rt_parmsout(void *prmsp, pc_vaparms_t *vaparmsp)
{
    rtkparms_t  *rtkprmsp = (rtkparms_t *)prmsp;

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

    if (rtkprmsp->rt_tqntm < 0) {
        /*
         * Quantum field set to special value (e.g. RT_TQINF)
         */
        ((rtparms_t *)rtkprmsp)->rt_tqnsecs = rtkprmsp->rt_tqntm;
        ((rtparms_t *)rtkprmsp)->rt_tqsecs = 0;
    } else {
        /* Convert quantum from ticks to seconds-nanoseconds */

        timestruc_t ts;
        TICK_TO_TIMESTRUC(rtkprmsp->rt_tqntm, &ts);
        ((rtparms_t *)rtkprmsp)->rt_tqsecs = ts.tv_sec;
        ((rtparms_t *)rtkprmsp)->rt_tqnsecs = ts.tv_nsec;
    }

    return (0);
}


/*
 * Copy all selected real-time class parameters to the user.
 * The parameters are specified by a key.
 */
static int
rt_vaparmsout(void *prmsp, pc_vaparms_t *vaparmsp)
{
    rtkparms_t  *rtkprmsp = (rtkparms_t *)prmsp;
    timestruc_t ts;
    uint_t      cnt;
    uint_t      secs;
    int     nsecs;
    int     priflag, secflag, nsecflag, sigflag;
    pc_vaparm_t *vpp = &vaparmsp->pc_parms[0];

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

    priflag = secflag = nsecflag = sigflag = 0;

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

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


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

        switch (vpp->pc_key) {
        case RT_KY_PRI:
            if (priflag++)
                return (EINVAL);
            if (copyout(&rtkprmsp->rt_pri,
                (caddr_t)(uintptr_t)vpp->pc_parm, sizeof (pri_t)))
                return (EFAULT);
            break;

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

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

        case RT_KY_TQSIG:
            if (sigflag++)
                return (EINVAL);
            if (copyout(&rtkprmsp->rt_tqsig,
                (caddr_t)(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 rtprocp
 * to those specified in the buffer pointed to by rtkprmsp.
 * Note that the parameters are expected to be in kernel format
 * (i.e. time quantm expressed in ticks).  Real time parameters copied
 * in from the user should be processed by rt_parmsin() before they are
 * passed to this function.
 */
static int
rt_parmsset(kthread_t *tx, void *prmsp, id_t reqpcid, cred_t *reqpcredp)
{
    rtkparms_t *rtkprmsp = (rtkparms_t *)prmsp;
    rtproc_t *rtpp = (rtproc_t *)tx->t_cldata;

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

    /*
     * 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 real-time class requires in addition
     * that the requesting thread be real-time unless it is privileged.
     * This may also have been checked previously but if our caller
     * passes us a credential structure we assume it hasn't and
     * we check it here.
     */
    if (reqpcredp != NULL && reqpcid != rt_cid &&
        secpolicy_setpriority(reqpcredp) != 0)
        return (EPERM);

    thread_lock(tx);
    if ((rtkprmsp->rt_cflags & RT_DOPRI) != 0) {
        rtpp->rt_pri = rtkprmsp->rt_pri;
        rt_change_priority(tx, rtpp);
    }
    if (rtkprmsp->rt_tqntm == RT_TQINF)
        rtpp->rt_pquantum = RT_TQINF;
    else if (rtkprmsp->rt_tqntm == RT_TQDEF)
        rtpp->rt_timeleft = rtpp->rt_pquantum =
            rt_dptbl[rtpp->rt_pri].rt_quantum;
    else if ((rtkprmsp->rt_cflags & RT_DOTQ) != 0)
        rtpp->rt_timeleft = rtpp->rt_pquantum = rtkprmsp->rt_tqntm;

    if ((rtkprmsp->rt_cflags & RT_DOSIG) != 0)
        rtpp->rt_tqsignal = rtkprmsp->rt_tqsig;

    thread_unlock(tx);
    return (0);
}


/*
 * Arrange for thread to be placed in appropriate location
 * on dispatcher queue.  Runs at splhi() since the clock
 * interrupt can cause RTBACKQ to be set.
 */
static void
rt_preempt(kthread_t *t)
{
    rtproc_t *rtpp = (rtproc_t *)(t->t_cldata);
    klwp_t *lwp;

    ASSERT(THREAD_LOCK_HELD(t));

    /*
     * If the state is user I allow swapping because I know I won't
     * be holding any locks.
     */
    if ((lwp = curthread->t_lwp) != NULL && lwp->lwp_state == LWP_USER)
        t->t_schedflag &= ~TS_DONT_SWAP;
    if ((rtpp->rt_flags & RTBACKQ) != 0) {
        rtpp->rt_timeleft = rtpp->rt_pquantum;
        rtpp->rt_flags &= ~RTBACKQ;
        setbackdq(t);
    } else
        setfrontdq(t);

}

/*
 * Return the global priority associated with this rt_pri.
 */
static pri_t
rt_globpri(kthread_t *t)
{
    rtproc_t *rtprocp = (rtproc_t *)t->t_cldata;
    return (rt_dptbl[rtprocp->rt_pri].rt_globpri);
}

static void
rt_setrun(kthread_t *t)
{
    rtproc_t *rtpp = (rtproc_t *)(t->t_cldata);

    ASSERT(THREAD_LOCK_HELD(t));

    rtpp->rt_timeleft = rtpp->rt_pquantum;
    rtpp->rt_flags &= ~RTBACKQ;
    setbackdq(t);
}

/*
 * Returns the priority of the thread, -1 if the thread is loaded or ineligible
 * for swapin.
 *
 * 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
rt_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;
    }

    return (tpri);
}

/*
 * Return an effective priority for swapout.
 */
/* ARGSUSED */
static pri_t
rt_swapout(kthread_t *t, int flags)
{
    ASSERT(THREAD_LOCK_HELD(t));

    return (-1);
}

/*
 * Check for time slice expiration (unless thread has infinite time
 * slice).  If time slice has expired arrange for thread to be preempted
 * and placed on back of queue.
 */
static void
rt_tick(kthread_t *t)
{
    rtproc_t *rtpp = (rtproc_t *)(t->t_cldata);

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

    thread_lock(t);
    if ((rtpp->rt_pquantum != RT_TQINF && --rtpp->rt_timeleft == 0) ||
        (DISP_MUST_SURRENDER(t))) {
        if (rtpp->rt_timeleft == 0 && rtpp->rt_tqsignal) {
            thread_unlock(t);
            sigtoproc(ttoproc(t), t, rtpp->rt_tqsignal);
            thread_lock(t);
        }
        rtpp->rt_flags |= RTBACKQ;
        cpu_surrender(t);
    }
    thread_unlock(t);
}


/*
 * Place the thread waking up on the dispatcher queue.
 */
static void
rt_wakeup(kthread_t *t)
{
    rtproc_t *rtpp = (rtproc_t *)(t->t_cldata);

    ASSERT(THREAD_LOCK_HELD(t));

    rtpp->rt_timeleft = rtpp->rt_pquantum;
    rtpp->rt_flags &= ~RTBACKQ;
    setbackdq(t);
}

static void
rt_yield(kthread_t *t)
{
    rtproc_t *rtpp = (rtproc_t *)(t->t_cldata);

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

    rtpp->rt_flags &= ~RTBACKQ;
    setbackdq(t);
}

/* ARGSUSED */
static int
rt_donice(kthread_t *t, cred_t *cr, int incr, int *retvalp)
{
    return (EINVAL);
}

static int
rt_alloc(void **p, int flag)
{
    void *bufp;
    bufp = kmem_alloc(sizeof (rtproc_t), flag);
    if (bufp == NULL) {
        return (ENOMEM);
    } else {
        *p = bufp;
        return (0);
    }
}

static void
rt_free(void *bufp)
{
    if (bufp)
        kmem_free(bufp, sizeof (rtproc_t));
}

static void
rt_change_priority(kthread_t *t, rtproc_t *rtpp)
{
    pri_t new_pri;

    ASSERT(THREAD_LOCK_HELD(t));

    new_pri = rt_dptbl[rtpp->rt_pri].rt_globpri;

    if (t == curthread || t->t_state == TS_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)) {
            rtpp->rt_flags |= RTBACKQ;
            cpu_surrender(t);
        } else {
            rtpp->rt_timeleft = rtpp->rt_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.
             */
            rtpp->rt_timeleft = rtpp->rt_pquantum;
        } else {
            rtpp->rt_flags |= RTBACKQ;
        }
    }
}