/*      $OpenBSD: hfsc.c,v 1.53 2026/03/19 14:59:05 sthen Exp $ */

/*
 * Copyright (c) 2012-2013 Henning Brauer <henning@openbsd.org>
 * Copyright (c) 1997-1999 Carnegie Mellon University. All Rights Reserved.
 *
 * Permission to use, copy, modify, and distribute this software and
 * its documentation is hereby granted (including for commercial or
 * for-profit use), 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.
 *
 * THIS SOFTWARE IS EXPERIMENTAL AND IS KNOWN TO HAVE BUGS, SOME OF
 * WHICH MAY HAVE SERIOUS CONSEQUENCES.  CARNEGIE MELLON PROVIDES THIS
 * SOFTWARE IN ITS ``AS IS'' CONDITION, AND ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL CARNEGIE MELLON UNIVERSITY BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
 * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
 * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
 * USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
 * DAMAGE.
 *
 * Carnegie Mellon encourages (but does not require) users of this
 * software to return any improvements or extensions that they make,
 * and to grant Carnegie Mellon the rights to redistribute these
 * changes without encumbrance.
 */
/*
 * H-FSC is described in Proceedings of SIGCOMM'97,
 * "A Hierarchical Fair Service Curve Algorithm for Link-Sharing,
 * Real-Time and Priority Service"
 * by Ion Stoica, Hui Zhang, and T. S. Eugene Ng.
 *
 * Oleg Cherevko <olwi@aq.ml.com.ua> added the upperlimit for link-sharing.
 * when a class has an upperlimit, the fit-time is computed from the
 * upperlimit service curve.  the link-sharing scheduler does not schedule
 * a class whose fit-time exceeds the current time.
 */

#include <sys/param.h>
#include <sys/malloc.h>
#include <sys/pool.h>
#include <sys/mbuf.h>
#include <sys/systm.h>
#include <sys/errno.h>
#include <sys/queue.h>
#include <sys/kernel.h>
#include <sys/timeout.h>

#include <net/if.h>
#include <net/if_var.h>

#include <net/pfvar.h>
#include <net/hfsc.h>

/*
 * kernel internal service curve representation
 *      coordinates are given by 64 bit unsigned integers.
 *      x-axis: unit is clock count.  for the intel x86 architecture,
 *              the raw Pentium TSC (Timestamp Counter) value is used.
 *              virtual time is also calculated in this time scale.
 *      y-axis: unit is byte.
 *
 *      the service curve parameters are converted to the internal
 *      representation.
 *      the slope values are scaled to avoid overflow.
 *      the inverse slope values as well as the y-projection of the 1st
 *      segment are kept in order to avoid 64-bit divide operations
 *      that are expensive on 32-bit architectures.
 *
 *  note: Intel Pentium TSC never wraps around in several thousands of years.
 *      x-axis doesn't wrap around for 1089 years with 1GHz clock.
 *      y-axis doesn't wrap around for 4358 years with 1Gbps bandwidth.
 */

/* kernel internal representation of a service curve */
struct hfsc_internal_sc {
        u_int64_t       sm1;    /* scaled slope of the 1st segment */
        u_int64_t       ism1;   /* scaled inverse-slope of the 1st segment */
        u_int64_t       dx;     /* the x-projection of the 1st segment */
        u_int64_t       dy;     /* the y-projection of the 1st segment */
        u_int64_t       sm2;    /* scaled slope of the 2nd segment */
        u_int64_t       ism2;   /* scaled inverse-slope of the 2nd segment */
};

/* runtime service curve */
struct hfsc_runtime_sc {
        u_int64_t       x;      /* current starting position on x-axis */
        u_int64_t       y;      /* current starting position on x-axis */
        u_int64_t       sm1;    /* scaled slope of the 1st segment */
        u_int64_t       ism1;   /* scaled inverse-slope of the 1st segment */
        u_int64_t       dx;     /* the x-projection of the 1st segment */
        u_int64_t       dy;     /* the y-projection of the 1st segment */
        u_int64_t       sm2;    /* scaled slope of the 2nd segment */
        u_int64_t       ism2;   /* scaled inverse-slope of the 2nd segment */
};

struct hfsc_classq {
        struct mbuf_list q;      /* Queue of packets */
        int              qlimit; /* Queue limit */
};

/* for TAILQ based ellist and actlist implementation */
struct hfsc_class;
TAILQ_HEAD(hfsc_eligible, hfsc_class);
TAILQ_HEAD(hfsc_active, hfsc_class);
#define hfsc_actlist_last(s)            TAILQ_LAST(s, hfsc_active)

struct hfsc_class {
        u_int           cl_id;          /* class id (just for debug) */
        u_int32_t       cl_handle;      /* class handle */
        int             cl_flags;       /* misc flags */

        struct hfsc_class *cl_parent;   /* parent class */
        struct hfsc_class *cl_siblings; /* sibling classes */
        struct hfsc_class *cl_children; /* child classes */

        struct hfsc_classq cl_q;        /* class queue structure */

        const struct pfq_ops *cl_qops;  /* queue manager */
        void            *cl_qdata;      /* queue manager data */
        void            *cl_cookie;     /* queue manager cookie */

        u_int64_t       cl_total;       /* total work in bytes */
        u_int64_t       cl_cumul;       /* cumulative work in bytes
                                           done by real-time criteria */
        u_int64_t       cl_d;           /* deadline */
        u_int64_t       cl_e;           /* eligible time */
        u_int64_t       cl_vt;          /* virtual time */
        u_int64_t       cl_f;           /* time when this class will fit for
                                           link-sharing, max(myf, cfmin) */
        u_int64_t       cl_myf;         /* my fit-time (as calculated from this
                                           class's own upperlimit curve) */
        u_int64_t       cl_myfadj;      /* my fit-time adjustment
                                           (to cancel history dependence) */
        u_int64_t       cl_cfmin;       /* earliest children's fit-time (used
                                           with cl_myf to obtain cl_f) */
        u_int64_t       cl_cvtmin;      /* minimal virtual time among the
                                           children fit for link-sharing
                                           (monotonic within a period) */
        u_int64_t       cl_vtadj;       /* intra-period cumulative vt
                                           adjustment */
        u_int64_t       cl_vtoff;       /* inter-period cumulative vt offset */
        u_int64_t       cl_cvtmax;      /* max child's vt in the last period */

        u_int64_t       cl_initvt;      /* init virtual time (for debugging) */

        struct hfsc_internal_sc *cl_rsc; /* internal real-time service curve */
        struct hfsc_internal_sc *cl_fsc; /* internal fair service curve */
        struct hfsc_internal_sc *cl_usc; /* internal upperlimit service curve */
        struct hfsc_runtime_sc   cl_deadline; /* deadline curve */
        struct hfsc_runtime_sc   cl_eligible; /* eligible curve */
        struct hfsc_runtime_sc   cl_virtual;  /* virtual curve */
        struct hfsc_runtime_sc   cl_ulimit;   /* upperlimit curve */

        u_int           cl_vtperiod;    /* vt period sequence no */
        u_int           cl_parentperiod;  /* parent's vt period seqno */
        int             cl_nactive;     /* number of active children */
        struct hfsc_active      cl_actc; /* active children list */

        TAILQ_ENTRY(hfsc_class) cl_actlist; /* active children list entry */
        TAILQ_ENTRY(hfsc_class) cl_ellist; /* eligible list entry */

        struct {
                struct hfsc_pktcntr xmit_cnt;
                struct hfsc_pktcntr drop_cnt;
                u_int period;
        } cl_stats;
};

/*
 * hfsc interface state
 */
struct hfsc_if {
        struct hfsc_if          *hif_next;      /* interface state list */
        struct hfsc_class       *hif_rootclass;         /* root class */
        struct hfsc_class       *hif_defaultclass;      /* default class */
        struct hfsc_class       **hif_class_tbl;

        u_int64_t               hif_microtime;  /* time at deq_begin */

        u_int   hif_allocated;                  /* # of slots in hif_class_tbl */
        u_int   hif_classes;                    /* # of classes in the tree */
        u_int   hif_classid;                    /* class id sequence number */

        struct hfsc_eligible hif_eligible;      /* eligible list */
        struct timeout hif_defer;       /* for queues that weren't ready */
};

/*
 * function prototypes
 */
struct hfsc_class       *hfsc_class_create(struct hfsc_if *,
                            struct hfsc_sc *, struct hfsc_sc *,
                            struct hfsc_sc *, struct hfsc_class *, int,
                            int, int);
int                      hfsc_class_destroy(struct hfsc_if *,
                            struct hfsc_class *);
struct hfsc_class       *hfsc_nextclass(struct hfsc_class *);

void             hfsc_cl_purge(struct hfsc_if *, struct hfsc_class *,
                     struct mbuf_list *);

void             hfsc_update_sc(struct hfsc_if *, struct hfsc_class *, int);
void             hfsc_deferred(void *);
void             hfsc_update_cfmin(struct hfsc_class *);
void             hfsc_set_active(struct hfsc_if *, struct hfsc_class *, int);
void             hfsc_set_passive(struct hfsc_if *, struct hfsc_class *);
void             hfsc_init_ed(struct hfsc_if *, struct hfsc_class *, int);
void             hfsc_update_ed(struct hfsc_if *, struct hfsc_class *, int);
void             hfsc_update_d(struct hfsc_class *, int);
void             hfsc_init_vf(struct hfsc_class *, int);
void             hfsc_update_vf(struct hfsc_class *, int, u_int64_t);
void             hfsc_ellist_insert(struct hfsc_if *, struct hfsc_class *);
void             hfsc_ellist_remove(struct hfsc_if *, struct hfsc_class *);
void             hfsc_ellist_update(struct hfsc_if *, struct hfsc_class *);
struct hfsc_class       *hfsc_ellist_get_mindl(struct hfsc_if *, u_int64_t);
void             hfsc_actlist_insert(struct hfsc_class *);
void             hfsc_actlist_remove(struct hfsc_class *);
void             hfsc_actlist_update(struct hfsc_class *);

struct hfsc_class       *hfsc_actlist_firstfit(struct hfsc_class *,
                                    u_int64_t);

static __inline u_int64_t       seg_x2y(u_int64_t, u_int64_t);
static __inline u_int64_t       seg_y2x(u_int64_t, u_int64_t);
static __inline u_int64_t       m2sm(u_int64_t);
static __inline u_int64_t       m2ism(u_int64_t);
static __inline u_int64_t       d2dx(u_int);
static __inline u_int64_t       sm2m(u_int64_t);
static __inline u_int           dx2d(u_int64_t);

void            hfsc_sc2isc(struct hfsc_sc *, struct hfsc_internal_sc *);
void            hfsc_rtsc_init(struct hfsc_runtime_sc *,
                    struct hfsc_internal_sc *, u_int64_t, u_int64_t);
u_int64_t       hfsc_rtsc_y2x(struct hfsc_runtime_sc *, u_int64_t);
u_int64_t       hfsc_rtsc_x2y(struct hfsc_runtime_sc *, u_int64_t);
void            hfsc_rtsc_min(struct hfsc_runtime_sc *,
                    struct hfsc_internal_sc *, u_int64_t, u_int64_t);

void            hfsc_getclstats(struct hfsc_class_stats *, struct hfsc_class *);
struct hfsc_class       *hfsc_clh2cph(struct hfsc_if *, u_int32_t);

#define HFSC_FREQ               1000000000LL
#define HFSC_CLK_PER_TICK       tick_nsec
#define HFSC_HT_INFINITY        0xffffffffffffffffLL /* infinite time value */

struct pool     hfsc_class_pl, hfsc_internal_sc_pl;

/*
 * ifqueue glue.
 */

unsigned int     hfsc_idx(unsigned int, const struct mbuf *);
struct mbuf     *hfsc_enq(struct ifqueue *, struct mbuf *);
struct mbuf     *hfsc_deq_begin(struct ifqueue *, void **);
void             hfsc_deq_commit(struct ifqueue *, struct mbuf *, void *);
void             hfsc_purge(struct ifqueue *, struct mbuf_list *);
void            *hfsc_alloc(unsigned int, void *);
void             hfsc_free(unsigned int, void *);

const struct ifq_ops hfsc_ops = {
        hfsc_idx,
        hfsc_enq,
        hfsc_deq_begin,
        hfsc_deq_commit,
        hfsc_purge,
        hfsc_alloc,
        hfsc_free,
};

const struct ifq_ops * const ifq_hfsc_ops = &hfsc_ops;

/*
 * pf queue glue.
 */

void            *hfsc_pf_alloc(struct ifnet *);
int              hfsc_pf_addqueue(void *, struct pf_queuespec *);
void             hfsc_pf_free(void *);
int              hfsc_pf_qstats(struct pf_queuespec *, void *, int *);
unsigned int     hfsc_pf_qlength(void *);
struct mbuf *    hfsc_pf_enqueue(void *, struct mbuf *);
struct mbuf *    hfsc_pf_deq_begin(void *, void **, struct mbuf_list *);
void             hfsc_pf_deq_commit(void *, struct mbuf *, void *);
void             hfsc_pf_purge(void *, struct mbuf_list *);

const struct pfq_ops hfsc_pf_ops = {
        hfsc_pf_alloc,
        hfsc_pf_addqueue,
        hfsc_pf_free,
        hfsc_pf_qstats,
        hfsc_pf_qlength,
        hfsc_pf_enqueue,
        hfsc_pf_deq_begin,
        hfsc_pf_deq_commit,
        hfsc_pf_purge
};

const struct pfq_ops * const pfq_hfsc_ops = &hfsc_pf_ops;

/*
 * shortcuts for repeated use
 */
static inline unsigned int
hfsc_class_qlength(struct hfsc_class *cl)
{
        /* Only leaf classes have a queue */
        if (cl->cl_qops != NULL)
                return cl->cl_qops->pfq_qlength(cl->cl_qdata);
        return 0;
}

static inline struct mbuf *
hfsc_class_enqueue(struct hfsc_class *cl, struct mbuf *m)
{
        return cl->cl_qops->pfq_enqueue(cl->cl_qdata, m);
}

static inline struct mbuf *
hfsc_class_deq_begin(struct hfsc_class *cl, struct mbuf_list *ml)
{
        return cl->cl_qops->pfq_deq_begin(cl->cl_qdata, &cl->cl_cookie, ml);
}

static inline void
hfsc_class_deq_commit(struct hfsc_class *cl, struct mbuf *m)
{
        return cl->cl_qops->pfq_deq_commit(cl->cl_qdata, m, cl->cl_cookie);
}

static inline void
hfsc_class_purge(struct hfsc_class *cl, struct mbuf_list *ml)
{
        /* Only leaf classes have a queue */
        if (cl->cl_qops != NULL)
                return cl->cl_qops->pfq_purge(cl->cl_qdata, ml);
}

static inline u_int
hfsc_more_slots(u_int current)
{
        u_int want = current * 2;

        return (want > HFSC_MAX_CLASSES ? HFSC_MAX_CLASSES : want);
}

static void
hfsc_grow_class_tbl(struct hfsc_if *hif, u_int howmany)
{
        struct hfsc_class **newtbl, **old;
        size_t oldlen = sizeof(void *) * hif->hif_allocated;

        newtbl = mallocarray(howmany, sizeof(void *), M_DEVBUF,
            M_WAITOK | M_ZERO);
        old = hif->hif_class_tbl;

        memcpy(newtbl, old, oldlen);
        hif->hif_class_tbl = newtbl;
        hif->hif_allocated = howmany;

        free(old, M_DEVBUF, oldlen);
}

void
hfsc_initialize(void)
{
        pool_init(&hfsc_class_pl, sizeof(struct hfsc_class), 0,
            IPL_NONE, PR_WAITOK, "hfscclass", NULL);
        pool_init(&hfsc_internal_sc_pl, sizeof(struct hfsc_internal_sc), 0,
            IPL_NONE, PR_WAITOK, "hfscintsc", NULL);
}

void *
hfsc_pf_alloc(struct ifnet *ifp)
{
        struct hfsc_if *hif;

        KASSERT(ifp != NULL);

        hif = malloc(sizeof(*hif), M_DEVBUF, M_WAITOK | M_ZERO);
        TAILQ_INIT(&hif->hif_eligible);
        hif->hif_class_tbl = mallocarray(HFSC_DEFAULT_CLASSES, sizeof(void *),
            M_DEVBUF, M_WAITOK | M_ZERO);
        hif->hif_allocated = HFSC_DEFAULT_CLASSES;

        timeout_set(&hif->hif_defer, hfsc_deferred, ifp);

        return (hif);
}

int
hfsc_pf_addqueue(void *arg, struct pf_queuespec *q)
{
        struct hfsc_if *hif = arg;
        struct hfsc_class *cl, *parent, *np = NULL;
        struct hfsc_sc rtsc, lssc, ulsc;
        int error = 0;

        KASSERT(hif != NULL);
        KASSERT(q->qid != 0);

        /* Root queue must have non-zero linksharing parameters */
        if (q->linkshare.m1.absolute == 0 && q->linkshare.m2.absolute == 0 &&
            q->parent_qid == 0)
                return (EINVAL);

        if (q->parent_qid == 0 && hif->hif_rootclass == NULL) {
                np = hfsc_class_create(hif, NULL, NULL, NULL, NULL,
                    0, 0, HFSC_ROOT_CLASS | q->qid);
                if (np == NULL)
                        return (EINVAL);
                parent = np;
        } else if ((parent = hfsc_clh2cph(hif, q->parent_qid)) == NULL)
                return (EINVAL);

        if (hfsc_clh2cph(hif, q->qid) != NULL) {
                hfsc_class_destroy(hif, np);
                return (EBUSY);
        }

        rtsc.m1 = q->realtime.m1.absolute;
        rtsc.d  = q->realtime.d;
        rtsc.m2 = q->realtime.m2.absolute;
        lssc.m1 = q->linkshare.m1.absolute;
        lssc.d  = q->linkshare.d;
        lssc.m2 = q->linkshare.m2.absolute;
        ulsc.m1 = q->upperlimit.m1.absolute;
        ulsc.d  = q->upperlimit.d;
        ulsc.m2 = q->upperlimit.m2.absolute;

        if ((cl = hfsc_class_create(hif, &rtsc, &lssc, &ulsc,
            parent, q->qlimit, q->flags, q->qid)) == NULL) {
                hfsc_class_destroy(hif, np);
                return (ENOMEM);
        }

        /* Attach a queue manager if specified */
        cl->cl_qops = pf_queue_manager(q);
        /* Realtime class cannot be used with an external queue manager */
        if (cl->cl_qops == NULL || cl->cl_rsc != NULL) {
                cl->cl_qops = pfq_hfsc_ops;
                cl->cl_qdata = &cl->cl_q;
        } else {
                cl->cl_qdata = cl->cl_qops->pfq_alloc(q->kif->pfik_ifp);
                if (cl->cl_qdata == NULL) {
                        cl->cl_qops = NULL;
                        hfsc_class_destroy(hif, cl);
                        hfsc_class_destroy(hif, np);
                        return (ENOMEM);
                }
                error = cl->cl_qops->pfq_addqueue(cl->cl_qdata, q);
                if (error) {
                        cl->cl_qops->pfq_free(cl->cl_qdata);
                        cl->cl_qops = NULL;
                        hfsc_class_destroy(hif, cl);
                        hfsc_class_destroy(hif, np);
                        return (error);
                }
        }

        KASSERT(cl->cl_qops != NULL);
        KASSERT(cl->cl_qdata != NULL);

        return (0);
}

int
hfsc_pf_qstats(struct pf_queuespec *q, void *ubuf, int *nbytes)
{
        struct ifnet *ifp = q->kif->pfik_ifp;
        struct hfsc_if *hif;
        struct hfsc_class *cl;
        struct hfsc_class_stats stats;
        int error = 0;

        if (ifp == NULL)
                return (EBADF);

        if (*nbytes < sizeof(stats))
                return (EINVAL);

        hif = ifq_q_enter(&ifp->if_snd, ifq_hfsc_ops);
        if (hif == NULL)
                return (EBADF);

        if ((cl = hfsc_clh2cph(hif, q->qid)) == NULL) {
                ifq_q_leave(&ifp->if_snd, hif);
                return (EINVAL);
        }

        hfsc_getclstats(&stats, cl);
        ifq_q_leave(&ifp->if_snd, hif);

        if ((error = copyout((caddr_t)&stats, ubuf, sizeof(stats))) != 0)
                return (error);

        *nbytes = sizeof(stats);
        return (0);
}

void
hfsc_pf_free(void *arg)
{
        hfsc_free(0, arg);
}

unsigned int
hfsc_pf_qlength(void *arg)
{
        struct hfsc_classq *cq = arg;

        return ml_len(&cq->q);
}

struct mbuf *
hfsc_pf_enqueue(void *arg, struct mbuf *m)
{
        struct hfsc_classq *cq = arg;

        if (ml_len(&cq->q) >= cq->qlimit)
                return (m);

        ml_enqueue(&cq->q, m);
        return (NULL);
}

struct mbuf *
hfsc_pf_deq_begin(void *arg, void **cookiep, struct mbuf_list *free_ml)
{
        struct hfsc_classq *cq = arg;

        return MBUF_LIST_FIRST(&cq->q);
}

void
hfsc_pf_deq_commit(void *arg, struct mbuf *m, void *cookie)
{
        struct hfsc_classq *cq = arg;

        ml_dequeue(&cq->q);
}

void
hfsc_pf_purge(void *arg, struct mbuf_list *ml)
{
        struct hfsc_classq *cq = arg;

        ml_enlist(ml, &cq->q);
}

unsigned int
hfsc_idx(unsigned int nqueues, const struct mbuf *m)
{
        /*
         * hfsc can only function on a single ifq and the stack understands
         * this. when the first ifq on an interface is switched to hfsc,
         * this gets used to map all mbufs to the first and only ifq that
         * is set up for hfsc.
         */
        return (0);
}

void *
hfsc_alloc(unsigned int idx, void *q)
{
        struct hfsc_if *hif = q;

        KASSERT(idx == 0); /* when hfsc is enabled we only use the first ifq */
        KASSERT(hif != NULL);
        return (hif);
}

void
hfsc_free(unsigned int idx, void *q)
{
        struct hfsc_if *hif = q;
        struct hfsc_class *cl;
        int i, restart;

        KERNEL_ASSERT_LOCKED();
        KASSERT(idx == 0); /* when hfsc is enabled we only use the first ifq */

        timeout_del(&hif->hif_defer);

        do {
                restart = 0;
                for (i = 0; i < hif->hif_allocated; i++) {
                        cl = hif->hif_class_tbl[i];
                        if (hfsc_class_destroy(hif, cl) == EBUSY)
                                restart++;
                }
        } while (restart > 0);

        free(hif->hif_class_tbl, M_DEVBUF, hif->hif_allocated * sizeof(void *));
        free(hif, M_DEVBUF, sizeof(*hif));
}

void
hfsc_purge(struct ifqueue *ifq, struct mbuf_list *ml)
{
        struct hfsc_if          *hif = ifq->ifq_q;
        struct hfsc_class       *cl;

        for (cl = hif->hif_rootclass; cl != NULL; cl = hfsc_nextclass(cl))
                hfsc_cl_purge(hif, cl, ml);
}

struct hfsc_class *
hfsc_class_create(struct hfsc_if *hif, struct hfsc_sc *rsc,
    struct hfsc_sc *fsc, struct hfsc_sc *usc, struct hfsc_class *parent,
    int qlimit, int flags, int qid)
{
        struct hfsc_class *cl, *p;
        int i, s;

        if (qlimit == 0)
                qlimit = HFSC_DEFAULT_QLIMIT;

        if (hif->hif_classes >= hif->hif_allocated) {
                u_int newslots = hfsc_more_slots(hif->hif_allocated);

                if (newslots == hif->hif_allocated)
                        return (NULL);
                hfsc_grow_class_tbl(hif, newslots);
        }

        cl = pool_get(&hfsc_class_pl, PR_WAITOK | PR_ZERO);
        TAILQ_INIT(&cl->cl_actc);

        ml_init(&cl->cl_q.q);
        cl->cl_q.qlimit = qlimit;
        cl->cl_flags = flags;

        if (rsc != NULL && (rsc->m1 != 0 || rsc->m2 != 0)) {
                cl->cl_rsc = pool_get(&hfsc_internal_sc_pl, PR_WAITOK);
                hfsc_sc2isc(rsc, cl->cl_rsc);
                hfsc_rtsc_init(&cl->cl_deadline, cl->cl_rsc, 0, 0);
                hfsc_rtsc_init(&cl->cl_eligible, cl->cl_rsc, 0, 0);
        }
        if (fsc != NULL && (fsc->m1 != 0 || fsc->m2 != 0)) {
                cl->cl_fsc = pool_get(&hfsc_internal_sc_pl, PR_WAITOK);
                hfsc_sc2isc(fsc, cl->cl_fsc);
                hfsc_rtsc_init(&cl->cl_virtual, cl->cl_fsc, 0, 0);
        }
        if (usc != NULL && (usc->m1 != 0 || usc->m2 != 0)) {
                cl->cl_usc = pool_get(&hfsc_internal_sc_pl, PR_WAITOK);
                hfsc_sc2isc(usc, cl->cl_usc);
                hfsc_rtsc_init(&cl->cl_ulimit, cl->cl_usc, 0, 0);
        }

        cl->cl_id = hif->hif_classid++;
        cl->cl_handle = qid;
        cl->cl_parent = parent;

        s = splnet();
        hif->hif_classes++;

        /*
         * find a free slot in the class table.  if the slot matching
         * the lower bits of qid is free, use this slot.  otherwise,
         * use the first free slot.
         */
        i = qid % hif->hif_allocated;
        if (hif->hif_class_tbl[i] == NULL)
                hif->hif_class_tbl[i] = cl;
        else {
                for (i = 0; i < hif->hif_allocated; i++)
                        if (hif->hif_class_tbl[i] == NULL) {
                                hif->hif_class_tbl[i] = cl;
                                break;
                        }
                if (i == hif->hif_allocated) {
                        splx(s);
                        goto err_ret;
                }
        }

        if (flags & HFSC_DEFAULTCLASS)
                hif->hif_defaultclass = cl;

        if (parent == NULL)
                hif->hif_rootclass = cl;
        else {
                /* add this class to the children list of the parent */
                if ((p = parent->cl_children) == NULL)
                        parent->cl_children = cl;
                else {
                        while (p->cl_siblings != NULL)
                                p = p->cl_siblings;
                        p->cl_siblings = cl;
                }
        }
        splx(s);

        return (cl);

err_ret:
        if (cl->cl_fsc != NULL)
                pool_put(&hfsc_internal_sc_pl, cl->cl_fsc);
        if (cl->cl_rsc != NULL)
                pool_put(&hfsc_internal_sc_pl, cl->cl_rsc);
        if (cl->cl_usc != NULL)
                pool_put(&hfsc_internal_sc_pl, cl->cl_usc);
        pool_put(&hfsc_class_pl, cl);
        return (NULL);
}

int
hfsc_class_destroy(struct hfsc_if *hif, struct hfsc_class *cl)
{
        int i, s;

        if (cl == NULL)
                return (0);

        if (cl->cl_children != NULL)
                return (EBUSY);

        s = splnet();
        KASSERT(hfsc_class_qlength(cl) == 0);

        if (cl->cl_parent != NULL) {
                struct hfsc_class *p = cl->cl_parent->cl_children;

                if (p == cl)
                        cl->cl_parent->cl_children = cl->cl_siblings;
                else do {
                        if (p->cl_siblings == cl) {
                                p->cl_siblings = cl->cl_siblings;
                                break;
                        }
                } while ((p = p->cl_siblings) != NULL);
        }

        for (i = 0; i < hif->hif_allocated; i++)
                if (hif->hif_class_tbl[i] == cl) {
                        hif->hif_class_tbl[i] = NULL;
                        break;
                }

        hif->hif_classes--;
        splx(s);

        KASSERT(TAILQ_EMPTY(&cl->cl_actc));

        if (cl == hif->hif_rootclass)
                hif->hif_rootclass = NULL;
        if (cl == hif->hif_defaultclass)
                hif->hif_defaultclass = NULL;

        /* Free external queue manager resources */
        if (cl->cl_qops && cl->cl_qops != pfq_hfsc_ops)
                cl->cl_qops->pfq_free(cl->cl_qdata);

        if (cl->cl_usc != NULL)
                pool_put(&hfsc_internal_sc_pl, cl->cl_usc);
        if (cl->cl_fsc != NULL)
                pool_put(&hfsc_internal_sc_pl, cl->cl_fsc);
        if (cl->cl_rsc != NULL)
                pool_put(&hfsc_internal_sc_pl, cl->cl_rsc);
        pool_put(&hfsc_class_pl, cl);

        return (0);
}

/*
 * hfsc_nextclass returns the next class in the tree.
 *   usage:
 *      for (cl = hif->hif_rootclass; cl != NULL; cl = hfsc_nextclass(cl))
 *              do_something;
 */
struct hfsc_class *
hfsc_nextclass(struct hfsc_class *cl)
{
        if (cl->cl_children != NULL)
                cl = cl->cl_children;
        else if (cl->cl_siblings != NULL)
                cl = cl->cl_siblings;
        else {
                while ((cl = cl->cl_parent) != NULL)
                        if (cl->cl_siblings) {
                                cl = cl->cl_siblings;
                                break;
                        }
        }

        return (cl);
}

struct mbuf *
hfsc_enq(struct ifqueue *ifq, struct mbuf *m)
{
        struct hfsc_if *hif = ifq->ifq_q;
        struct hfsc_class *cl;
        struct mbuf *dm;

        if ((cl = hfsc_clh2cph(hif, m->m_pkthdr.pf.qid)) == NULL ||
            cl->cl_children != NULL) {
                cl = hif->hif_defaultclass;
                if (cl == NULL)
                        return (m);
        }

        dm = hfsc_class_enqueue(cl, m);

        /* successfully queued. */
        if (dm != m && hfsc_class_qlength(cl) == 1) {
                hfsc_set_active(hif, cl, m->m_pkthdr.len);
                if (!timeout_pending(&hif->hif_defer))
                        timeout_add(&hif->hif_defer, 1);
        }

        /* drop occurred. */
        if (dm != NULL)
                PKTCNTR_INC(&cl->cl_stats.drop_cnt, dm->m_pkthdr.len);

        return (dm);
}

struct mbuf *
hfsc_deq_begin(struct ifqueue *ifq, void **cookiep)
{
        struct mbuf_list free_ml = MBUF_LIST_INITIALIZER();
        struct hfsc_if *hif = ifq->ifq_q;
        struct hfsc_class *cl, *tcl;
        struct mbuf *m;
        u_int64_t cur_time;

        cur_time = nsecuptime();

        /*
         * if there are eligible classes, use real-time criteria.
         * find the class with the minimum deadline among
         * the eligible classes.
         */
        cl = hfsc_ellist_get_mindl(hif, cur_time);
        if (cl == NULL) {
                /*
                 * use link-sharing criteria
                 * get the class with the minimum vt in the hierarchy
                 */
                cl = NULL;
                tcl = hif->hif_rootclass;

                while (tcl != NULL && tcl->cl_children != NULL) {
                        tcl = hfsc_actlist_firstfit(tcl, cur_time);
                        if (tcl == NULL)
                                continue;

                        /*
                         * update parent's cl_cvtmin.
                         * don't update if the new vt is smaller.
                         */
                        if (tcl->cl_parent->cl_cvtmin < tcl->cl_vt)
                                tcl->cl_parent->cl_cvtmin = tcl->cl_vt;

                        cl = tcl;
                }
                /* XXX HRTIMER plan hfsc_deferred precisely here. */
                if (cl == NULL)
                        return (NULL);
        }

        m = hfsc_class_deq_begin(cl, &free_ml);
        ifq_mfreeml(ifq, &free_ml);
        if (m == NULL) {
                hfsc_update_sc(hif, cl, 0);
                return (NULL);
        }

        hif->hif_microtime = cur_time;
        *cookiep = cl;
        return (m);
}

void
hfsc_deq_commit(struct ifqueue *ifq, struct mbuf *m, void *cookie)
{
        struct hfsc_if *hif = ifq->ifq_q;
        struct hfsc_class *cl = cookie;

        hfsc_class_deq_commit(cl, m);
        hfsc_update_sc(hif, cl, m->m_pkthdr.len);

        PKTCNTR_INC(&cl->cl_stats.xmit_cnt, m->m_pkthdr.len);
}

void
hfsc_update_sc(struct hfsc_if *hif, struct hfsc_class *cl, int len)
{
        int next_len, realtime = 0;
        u_int64_t cur_time = hif->hif_microtime;

        /* check if the class was scheduled by real-time criteria */
        if (cl->cl_rsc != NULL)
                realtime = (cl->cl_e <= cur_time);

        hfsc_update_vf(cl, len, cur_time);
        if (realtime)
                cl->cl_cumul += len;

        if (hfsc_class_qlength(cl) > 0) {
                /*
                 * Realtime queue needs to look into the future and make
                 * calculations based on that. This is the reason it can't
                 * be used with an external queue manager.
                 */
                if (cl->cl_rsc != NULL) {
                        struct mbuf *m0;

                        /* update ed */
                        KASSERT(cl->cl_qops == pfq_hfsc_ops);
                        m0 = MBUF_LIST_FIRST(&cl->cl_q.q);
                        next_len = m0->m_pkthdr.len;

                        if (realtime)
                                hfsc_update_ed(hif, cl, next_len);
                        else
                                hfsc_update_d(cl, next_len);
                }
        } else {
                /* the class becomes passive */
                hfsc_set_passive(hif, cl);
        }
}

void
hfsc_deferred(void *arg)
{
        struct ifnet *ifp = arg;
        struct ifqueue *ifq = &ifp->if_snd;
        struct hfsc_if *hif;

        if (!HFSC_ENABLED(ifq))
                return;

        if (!ifq_empty(ifq))
                ifq_start(ifq);

        hif = ifq_q_enter(&ifp->if_snd, ifq_hfsc_ops);
        if (hif == NULL)
                return;
        /* XXX HRTIMER nearest virtual/fit time is likely less than 1/HZ. */
        timeout_add(&hif->hif_defer, 1);
        ifq_q_leave(&ifp->if_snd, hif);
}

void
hfsc_cl_purge(struct hfsc_if *hif, struct hfsc_class *cl, struct mbuf_list *ml)
{
        struct mbuf_list ml2 = MBUF_LIST_INITIALIZER();

        hfsc_class_purge(cl, &ml2);
        if (ml_empty(&ml2))
                return;

        ml_enlist(ml, &ml2);

        hfsc_update_vf(cl, 0, 0);       /* remove cl from the actlist */
        hfsc_set_passive(hif, cl);
}

void
hfsc_set_active(struct hfsc_if *hif, struct hfsc_class *cl, int len)
{
        if (cl->cl_rsc != NULL)
                hfsc_init_ed(hif, cl, len);
        if (cl->cl_fsc != NULL)
                hfsc_init_vf(cl, len);

        cl->cl_stats.period++;
}

void
hfsc_set_passive(struct hfsc_if *hif, struct hfsc_class *cl)
{
        if (cl->cl_rsc != NULL)
                hfsc_ellist_remove(hif, cl);

        /*
         * actlist is handled in hfsc_update_vf() so that hfsc_update_vf(cl, 0,
         * 0) needs to be called explicitly to remove a class from actlist
         */
}

void
hfsc_init_ed(struct hfsc_if *hif, struct hfsc_class *cl, int next_len)
{
        u_int64_t cur_time;

        cur_time = nsecuptime();

        /* update the deadline curve */
        hfsc_rtsc_min(&cl->cl_deadline, cl->cl_rsc, cur_time, cl->cl_cumul);

        /*
         * update the eligible curve.
         * for concave, it is equal to the deadline curve.
         * for convex, it is a linear curve with slope m2.
         */
        cl->cl_eligible = cl->cl_deadline;
        if (cl->cl_rsc->sm1 <= cl->cl_rsc->sm2) {
                cl->cl_eligible.dx = 0;
                cl->cl_eligible.dy = 0;
        }

        /* compute e and d */
        cl->cl_e = hfsc_rtsc_y2x(&cl->cl_eligible, cl->cl_cumul);
        cl->cl_d = hfsc_rtsc_y2x(&cl->cl_deadline, cl->cl_cumul + next_len);

        hfsc_ellist_insert(hif, cl);
}

void
hfsc_update_ed(struct hfsc_if *hif, struct hfsc_class *cl, int next_len)
{
        cl->cl_e = hfsc_rtsc_y2x(&cl->cl_eligible, cl->cl_cumul);
        cl->cl_d = hfsc_rtsc_y2x(&cl->cl_deadline, cl->cl_cumul + next_len);

        hfsc_ellist_update(hif, cl);
}

void
hfsc_update_d(struct hfsc_class *cl, int next_len)
{
        cl->cl_d = hfsc_rtsc_y2x(&cl->cl_deadline, cl->cl_cumul + next_len);
}

void
hfsc_init_vf(struct hfsc_class *cl, int len)
{
        struct hfsc_class *max_cl, *p;
        u_int64_t vt, f, cur_time;
        int go_active;

        cur_time = 0;
        go_active = 1;
        for ( ; cl->cl_parent != NULL; cl = cl->cl_parent) {
                if (go_active && cl->cl_nactive++ == 0)
                        go_active = 1;
                else
                        go_active = 0;

                if (go_active) {
                        max_cl = TAILQ_LAST(&cl->cl_parent->cl_actc,
                            hfsc_active);
                        if (max_cl != NULL) {
                                /*
                                 * set vt to the average of the min and max
                                 * classes.  if the parent's period didn't
                                 * change, don't decrease vt of the class.
                                 */
                                vt = max_cl->cl_vt;
                                if (cl->cl_parent->cl_cvtmin != 0)
                                        vt = (cl->cl_parent->cl_cvtmin + vt)/2;

                                if (cl->cl_parent->cl_vtperiod !=
                                    cl->cl_parentperiod || vt > cl->cl_vt)
                                        cl->cl_vt = vt;
                        } else {
                                /*
                                 * first child for a new parent backlog period.
                                 * add parent's cvtmax to vtoff of children
                                 * to make a new vt (vtoff + vt) larger than
                                 * the vt in the last period for all children.
                                 */
                                vt = cl->cl_parent->cl_cvtmax;
                                for (p = cl->cl_parent->cl_children; p != NULL;
                                     p = p->cl_siblings)
                                        p->cl_vtoff += vt;
                                cl->cl_vt = 0;
                                cl->cl_parent->cl_cvtmax = 0;
                                cl->cl_parent->cl_cvtmin = 0;
                        }
                        cl->cl_initvt = cl->cl_vt;

                        /* update the virtual curve */
                        vt = cl->cl_vt + cl->cl_vtoff;
                        hfsc_rtsc_min(&cl->cl_virtual, cl->cl_fsc, vt,
                            cl->cl_total);
                        if (cl->cl_virtual.x == vt) {
                                cl->cl_virtual.x -= cl->cl_vtoff;
                                cl->cl_vtoff = 0;
                        }
                        cl->cl_vtadj = 0;

                        cl->cl_vtperiod++;  /* increment vt period */
                        cl->cl_parentperiod = cl->cl_parent->cl_vtperiod;
                        if (cl->cl_parent->cl_nactive == 0)
                                cl->cl_parentperiod++;
                        cl->cl_f = 0;

                        hfsc_actlist_insert(cl);

                        if (cl->cl_usc != NULL) {
                                /* class has upper limit curve */
                                if (cur_time == 0)
                                        cur_time = nsecuptime();

                                /* update the ulimit curve */
                                hfsc_rtsc_min(&cl->cl_ulimit, cl->cl_usc, cur_time,
                                    cl->cl_total);
                                /* compute myf */
                                cl->cl_myf = hfsc_rtsc_y2x(&cl->cl_ulimit,
                                    cl->cl_total);
                                cl->cl_myfadj = 0;
                        }
                }

                if (cl->cl_myf > cl->cl_cfmin)
                        f = cl->cl_myf;
                else
                        f = cl->cl_cfmin;
                if (f != cl->cl_f) {
                        cl->cl_f = f;
                        hfsc_update_cfmin(cl->cl_parent);
                }
        }
}

void
hfsc_update_vf(struct hfsc_class *cl, int len, u_int64_t cur_time)
{
        u_int64_t f, myf_bound, delta;
        int go_passive = 0;

        if (hfsc_class_qlength(cl) == 0)
                go_passive = 1;

        for (; cl->cl_parent != NULL; cl = cl->cl_parent) {
                cl->cl_total += len;

                if (cl->cl_fsc == NULL || cl->cl_nactive == 0)
                        continue;

                if (go_passive && --cl->cl_nactive == 0)
                        go_passive = 1;
                else
                        go_passive = 0;

                if (go_passive) {
                        /* no more active child, going passive */

                        /* update cvtmax of the parent class */
                        if (cl->cl_vt > cl->cl_parent->cl_cvtmax)
                                cl->cl_parent->cl_cvtmax = cl->cl_vt;

                        /* remove this class from the vt list */
                        hfsc_actlist_remove(cl);

                        hfsc_update_cfmin(cl->cl_parent);

                        continue;
                }

                /*
                 * update vt and f
                 */
                cl->cl_vt = hfsc_rtsc_y2x(&cl->cl_virtual, cl->cl_total)
                    - cl->cl_vtoff + cl->cl_vtadj;

                /*
                 * if vt of the class is smaller than cvtmin,
                 * the class was skipped in the past due to non-fit.
                 * if so, we need to adjust vtadj.
                 */
                if (cl->cl_vt < cl->cl_parent->cl_cvtmin) {
                        cl->cl_vtadj += cl->cl_parent->cl_cvtmin - cl->cl_vt;
                        cl->cl_vt = cl->cl_parent->cl_cvtmin;
                }

                /* update the vt list */
                hfsc_actlist_update(cl);

                if (cl->cl_usc != NULL) {
                        cl->cl_myf = cl->cl_myfadj +
                            hfsc_rtsc_y2x(&cl->cl_ulimit, cl->cl_total);

                        /*
                         * if myf lags behind by more than one clock tick
                         * from the current time, adjust myfadj to prevent
                         * a rate-limited class from going greedy.
                         * in a steady state under rate-limiting, myf
                         * fluctuates within one clock tick.
                         */
                        myf_bound = cur_time - HFSC_CLK_PER_TICK;
                        if (cl->cl_myf < myf_bound) {
                                delta = cur_time - cl->cl_myf;
                                cl->cl_myfadj += delta;
                                cl->cl_myf += delta;
                        }
                }

                /* cl_f is max(cl_myf, cl_cfmin) */
                if (cl->cl_myf > cl->cl_cfmin)
                        f = cl->cl_myf;
                else
                        f = cl->cl_cfmin;
                if (f != cl->cl_f) {
                        cl->cl_f = f;
                        hfsc_update_cfmin(cl->cl_parent);
                }
        }
}

void
hfsc_update_cfmin(struct hfsc_class *cl)
{
        struct hfsc_class *p;
        u_int64_t cfmin;

        if (TAILQ_EMPTY(&cl->cl_actc)) {
                cl->cl_cfmin = 0;
                return;
        }
        cfmin = HFSC_HT_INFINITY;
        TAILQ_FOREACH(p, &cl->cl_actc, cl_actlist) {
                if (p->cl_f == 0) {
                        cl->cl_cfmin = 0;
                        return;
                }
                if (p->cl_f < cfmin)
                        cfmin = p->cl_f;
        }
        cl->cl_cfmin = cfmin;
}

/*
 * eligible list holds backlogged classes being sorted by their eligible times.
 * there is one eligible list per interface.
 */
void
hfsc_ellist_insert(struct hfsc_if *hif, struct hfsc_class *cl)
{
        struct hfsc_class *p;

        /* check the last entry first */
        if ((p = TAILQ_LAST(&hif->hif_eligible, hfsc_eligible)) == NULL ||
            p->cl_e <= cl->cl_e) {
                TAILQ_INSERT_TAIL(&hif->hif_eligible, cl, cl_ellist);
                return;
        }

        TAILQ_FOREACH(p, &hif->hif_eligible, cl_ellist) {
                if (cl->cl_e < p->cl_e) {
                        TAILQ_INSERT_BEFORE(p, cl, cl_ellist);
                        return;
                }
        }
}

void
hfsc_ellist_remove(struct hfsc_if *hif, struct hfsc_class *cl)
{
        TAILQ_REMOVE(&hif->hif_eligible, cl, cl_ellist);
}

void
hfsc_ellist_update(struct hfsc_if *hif, struct hfsc_class *cl)
{
        struct hfsc_class *p, *last;

        /*
         * the eligible time of a class increases monotonically.
         * if the next entry has a larger eligible time, nothing to do.
         */
        p = TAILQ_NEXT(cl, cl_ellist);
        if (p == NULL || cl->cl_e <= p->cl_e)
                return;

        /* check the last entry */
        last = TAILQ_LAST(&hif->hif_eligible, hfsc_eligible);
        if (last->cl_e <= cl->cl_e) {
                TAILQ_REMOVE(&hif->hif_eligible, cl, cl_ellist);
                TAILQ_INSERT_TAIL(&hif->hif_eligible, cl, cl_ellist);
                return;
        }

        /*
         * the new position must be between the next entry
         * and the last entry
         */
        while ((p = TAILQ_NEXT(p, cl_ellist)) != NULL) {
                if (cl->cl_e < p->cl_e) {
                        TAILQ_REMOVE(&hif->hif_eligible, cl, cl_ellist);
                        TAILQ_INSERT_BEFORE(p, cl, cl_ellist);
                        return;
                }
        }
}

/* find the class with the minimum deadline among the eligible classes */
struct hfsc_class *
hfsc_ellist_get_mindl(struct hfsc_if *hif, u_int64_t cur_time)
{
        struct hfsc_class *p, *cl = NULL;

        TAILQ_FOREACH(p, &hif->hif_eligible, cl_ellist) {
                if (p->cl_e > cur_time)
                        break;
                if (cl == NULL || p->cl_d < cl->cl_d)
                        cl = p;
        }
        return (cl);
}

/*
 * active children list holds backlogged child classes being sorted
 * by their virtual time.
 * each intermediate class has one active children list.
 */
void
hfsc_actlist_insert(struct hfsc_class *cl)
{
        struct hfsc_class *p;

        /* check the last entry first */
        if ((p = TAILQ_LAST(&cl->cl_parent->cl_actc, hfsc_active)) == NULL
            || p->cl_vt <= cl->cl_vt) {
                TAILQ_INSERT_TAIL(&cl->cl_parent->cl_actc, cl, cl_actlist);
                return;
        }

        TAILQ_FOREACH(p, &cl->cl_parent->cl_actc, cl_actlist) {
                if (cl->cl_vt < p->cl_vt) {
                        TAILQ_INSERT_BEFORE(p, cl, cl_actlist);
                        return;
                }
        }
}

void
hfsc_actlist_remove(struct hfsc_class *cl)
{
        TAILQ_REMOVE(&cl->cl_parent->cl_actc, cl, cl_actlist);
}

void
hfsc_actlist_update(struct hfsc_class *cl)
{
        struct hfsc_class *p, *last;

        /*
         * the virtual time of a class increases monotonically during its
         * backlogged period.
         * if the next entry has a larger virtual time, nothing to do.
         */
        p = TAILQ_NEXT(cl, cl_actlist);
        if (p == NULL || cl->cl_vt < p->cl_vt)
                return;

        /* check the last entry */
        last = TAILQ_LAST(&cl->cl_parent->cl_actc, hfsc_active);
        if (last->cl_vt <= cl->cl_vt) {
                TAILQ_REMOVE(&cl->cl_parent->cl_actc, cl, cl_actlist);
                TAILQ_INSERT_TAIL(&cl->cl_parent->cl_actc, cl, cl_actlist);
                return;
        }

        /*
         * the new position must be between the next entry
         * and the last entry
         */
        while ((p = TAILQ_NEXT(p, cl_actlist)) != NULL) {
                if (cl->cl_vt < p->cl_vt) {
                        TAILQ_REMOVE(&cl->cl_parent->cl_actc, cl, cl_actlist);
                        TAILQ_INSERT_BEFORE(p, cl, cl_actlist);
                        return;
                }
        }
}

struct hfsc_class *
hfsc_actlist_firstfit(struct hfsc_class *cl, u_int64_t cur_time)
{
        struct hfsc_class *p;

        TAILQ_FOREACH(p, &cl->cl_actc, cl_actlist)
                if (p->cl_f <= cur_time)
                        return (p);

        return (NULL);
}

/*
 * service curve support functions
 *
 *  external service curve parameters
 *      m: bits/sec
 *      d: msec
 *  internal service curve parameters
 *      sm: (bytes/tsc_interval) << SM_SHIFT
 *      ism: (tsc_count/byte) << ISM_SHIFT
 *      dx: tsc_count
 *
 * SM_SHIFT and ISM_SHIFT are scaled in order to keep effective digits.
 * we should be able to handle 100K-1Gbps linkspeed with 200Hz-1GHz CPU
 * speed.  SM_SHIFT and ISM_SHIFT are selected to have at least 3 effective
 * digits in decimal using the following table.
 *
 *  bits/sec    100Kbps     1Mbps     10Mbps     100Mbps    1Gbps
 *  ----------+-------------------------------------------------------
 *  bytes/nsec  12.5e-6    125e-6     1250e-6    12500e-6   125000e-6
 *  sm(500MHz)  25.0e-6    250e-6     2500e-6    25000e-6   250000e-6
 *  sm(200MHz)  62.5e-6    625e-6     6250e-6    62500e-6   625000e-6
 *
 *  nsec/byte   80000      8000       800        80         8
 *  ism(500MHz) 40000      4000       400        40         4
 *  ism(200MHz) 16000      1600       160        16         1.6
 */
#define SM_SHIFT        24
#define ISM_SHIFT       10

#define SM_MASK         ((1LL << SM_SHIFT) - 1)
#define ISM_MASK        ((1LL << ISM_SHIFT) - 1)

static __inline u_int64_t
seg_x2y(u_int64_t x, u_int64_t sm)
{
        u_int64_t y;

        /*
         * compute
         *      y = x * sm >> SM_SHIFT
         * but divide it for the upper and lower bits to avoid overflow
         */
        y = (x >> SM_SHIFT) * sm + (((x & SM_MASK) * sm) >> SM_SHIFT);
        return (y);
}

static __inline u_int64_t
seg_y2x(u_int64_t y, u_int64_t ism)
{
        u_int64_t x;

        if (y == 0)
                x = 0;
        else if (ism == HFSC_HT_INFINITY)
                x = HFSC_HT_INFINITY;
        else {
                x = (y >> ISM_SHIFT) * ism
                    + (((y & ISM_MASK) * ism) >> ISM_SHIFT);
        }
        return (x);
}

static __inline u_int64_t
m2sm(u_int64_t m)
{
        u_int64_t sm;

        sm = (m << SM_SHIFT) / 8 / HFSC_FREQ;
        return (sm);
}

static __inline u_int64_t
m2ism(u_int64_t m)
{
        u_int64_t ism;

        if (m == 0)
                ism = HFSC_HT_INFINITY;
        else
                ism = ((u_int64_t)HFSC_FREQ << ISM_SHIFT) * 8 / m;
        return (ism);
}

static __inline u_int64_t
d2dx(u_int d)
{
        u_int64_t dx;

        dx = ((u_int64_t)d * HFSC_FREQ) / 1000;
        return (dx);
}

static __inline u_int64_t
sm2m(u_int64_t sm)
{
        u_int64_t m;

        m = (sm * 8 * HFSC_FREQ) >> SM_SHIFT;
        return (m);
}

static __inline u_int
dx2d(u_int64_t dx)
{
        u_int64_t d;

        d = dx * 1000 / HFSC_FREQ;
        return ((u_int)d);
}

void
hfsc_sc2isc(struct hfsc_sc *sc, struct hfsc_internal_sc *isc)
{
        isc->sm1 = m2sm(sc->m1);
        isc->ism1 = m2ism(sc->m1);
        isc->dx = d2dx(sc->d);
        isc->dy = seg_x2y(isc->dx, isc->sm1);
        isc->sm2 = m2sm(sc->m2);
        isc->ism2 = m2ism(sc->m2);
}

/*
 * initialize the runtime service curve with the given internal
 * service curve starting at (x, y).
 */
void
hfsc_rtsc_init(struct hfsc_runtime_sc *rtsc, struct hfsc_internal_sc * isc,
    u_int64_t x, u_int64_t y)
{
        rtsc->x =       x;
        rtsc->y =       y;
        rtsc->sm1 =     isc->sm1;
        rtsc->ism1 =    isc->ism1;
        rtsc->dx =      isc->dx;
        rtsc->dy =      isc->dy;
        rtsc->sm2 =     isc->sm2;
        rtsc->ism2 =    isc->ism2;
}

/*
 * calculate the y-projection of the runtime service curve by the
 * given x-projection value
 */
u_int64_t
hfsc_rtsc_y2x(struct hfsc_runtime_sc *rtsc, u_int64_t y)
{
        u_int64_t x;

        if (y < rtsc->y)
                x = rtsc->x;
        else if (y <= rtsc->y + rtsc->dy) {
                /* x belongs to the 1st segment */
                if (rtsc->dy == 0)
                        x = rtsc->x + rtsc->dx;
                else
                        x = rtsc->x + seg_y2x(y - rtsc->y, rtsc->ism1);
        } else {
                /* x belongs to the 2nd segment */
                x = rtsc->x + rtsc->dx
                    + seg_y2x(y - rtsc->y - rtsc->dy, rtsc->ism2);
        }
        return (x);
}

u_int64_t
hfsc_rtsc_x2y(struct hfsc_runtime_sc *rtsc, u_int64_t x)
{
        u_int64_t y;

        if (x <= rtsc->x)
                y = rtsc->y;
        else if (x <= rtsc->x + rtsc->dx)
                /* y belongs to the 1st segment */
                y = rtsc->y + seg_x2y(x - rtsc->x, rtsc->sm1);
        else
                /* y belongs to the 2nd segment */
                y = rtsc->y + rtsc->dy
                    + seg_x2y(x - rtsc->x - rtsc->dx, rtsc->sm2);
        return (y);
}

/*
 * update the runtime service curve by taking the minimum of the current
 * runtime service curve and the service curve starting at (x, y).
 */
void
hfsc_rtsc_min(struct hfsc_runtime_sc *rtsc, struct hfsc_internal_sc *isc,
    u_int64_t x, u_int64_t y)
{
        u_int64_t y1, y2, dx, dy;

        if (isc->sm1 <= isc->sm2) {
                /* service curve is convex */
                y1 = hfsc_rtsc_x2y(rtsc, x);
                if (y1 < y)
                        /* the current rtsc is smaller */
                        return;
                rtsc->x = x;
                rtsc->y = y;
                return;
        }

        /*
         * service curve is concave
         * compute the two y values of the current rtsc
         *      y1: at x
         *      y2: at (x + dx)
         */
        y1 = hfsc_rtsc_x2y(rtsc, x);
        if (y1 <= y) {
                /* rtsc is below isc, no change to rtsc */
                return;
        }

        y2 = hfsc_rtsc_x2y(rtsc, x + isc->dx);
        if (y2 >= y + isc->dy) {
                /* rtsc is above isc, replace rtsc by isc */
                rtsc->x = x;
                rtsc->y = y;
                rtsc->dx = isc->dx;
                rtsc->dy = isc->dy;
                return;
        }

        /*
         * the two curves intersect
         * compute the offsets (dx, dy) using the reverse
         * function of seg_x2y()
         *      seg_x2y(dx, sm1) == seg_x2y(dx, sm2) + (y1 - y)
         */
        dx = ((y1 - y) << SM_SHIFT) / (isc->sm1 - isc->sm2);
        /*
         * check if (x, y1) belongs to the 1st segment of rtsc.
         * if so, add the offset.
         */
        if (rtsc->x + rtsc->dx > x)
                dx += rtsc->x + rtsc->dx - x;
        dy = seg_x2y(dx, isc->sm1);

        rtsc->x = x;
        rtsc->y = y;
        rtsc->dx = dx;
        rtsc->dy = dy;
        return;
}

void
hfsc_getclstats(struct hfsc_class_stats *sp, struct hfsc_class *cl)
{
        sp->class_id = cl->cl_id;
        sp->class_handle = cl->cl_handle;

        if (cl->cl_rsc != NULL) {
                sp->rsc.m1 = sm2m(cl->cl_rsc->sm1);
                sp->rsc.d = dx2d(cl->cl_rsc->dx);
                sp->rsc.m2 = sm2m(cl->cl_rsc->sm2);
        } else {
                sp->rsc.m1 = 0;
                sp->rsc.d = 0;
                sp->rsc.m2 = 0;
        }
        if (cl->cl_fsc != NULL) {
                sp->fsc.m1 = sm2m(cl->cl_fsc->sm1);
                sp->fsc.d = dx2d(cl->cl_fsc->dx);
                sp->fsc.m2 = sm2m(cl->cl_fsc->sm2);
        } else {
                sp->fsc.m1 = 0;
                sp->fsc.d = 0;
                sp->fsc.m2 = 0;
        }
        if (cl->cl_usc != NULL) {
                sp->usc.m1 = sm2m(cl->cl_usc->sm1);
                sp->usc.d = dx2d(cl->cl_usc->dx);
                sp->usc.m2 = sm2m(cl->cl_usc->sm2);
        } else {
                sp->usc.m1 = 0;
                sp->usc.d = 0;
                sp->usc.m2 = 0;
        }

        sp->total = cl->cl_total;
        sp->cumul = cl->cl_cumul;

        sp->d = cl->cl_d;
        sp->e = cl->cl_e;
        sp->vt = cl->cl_vt;
        sp->f = cl->cl_f;

        sp->initvt = cl->cl_initvt;
        sp->vtperiod = cl->cl_vtperiod;
        sp->parentperiod = cl->cl_parentperiod;
        sp->nactive = cl->cl_nactive;
        sp->vtoff = cl->cl_vtoff;
        sp->cvtmax = cl->cl_cvtmax;
        sp->myf = cl->cl_myf;
        sp->cfmin = cl->cl_cfmin;
        sp->cvtmin = cl->cl_cvtmin;
        sp->myfadj = cl->cl_myfadj;
        sp->vtadj = cl->cl_vtadj;

        sp->cur_time = nsecuptime();
        sp->machclk_freq = HFSC_FREQ;

        sp->qlength = hfsc_class_qlength(cl);
        sp->qlimit = cl->cl_q.qlimit;
        sp->xmit_cnt = cl->cl_stats.xmit_cnt;
        sp->drop_cnt = cl->cl_stats.drop_cnt;
        sp->period = cl->cl_stats.period;

        sp->qtype = 0;
}

/* convert a class handle to the corresponding class pointer */
struct hfsc_class *
hfsc_clh2cph(struct hfsc_if *hif, u_int32_t chandle)
{
        int i;
        struct hfsc_class *cl;

        if (chandle == 0)
                return (NULL);
        /*
         * first, try the slot corresponding to the lower bits of the handle.
         * if it does not match, do the linear table search.
         */
        i = chandle % hif->hif_allocated;
        if ((cl = hif->hif_class_tbl[i]) != NULL && cl->cl_handle == chandle)
                return (cl);
        for (i = 0; i < hif->hif_allocated; i++)
                if ((cl = hif->hif_class_tbl[i]) != NULL &&
                    cl->cl_handle == chandle)
                        return (cl);
        return (NULL);
}