sch_prio.c

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/*
 * net/sched/sch_prio.c Simple 3-band priority "scheduler".
 *
 *      This program is free software; you can redistribute it and/or
 *      modify it under the terms of the GNU General Public License
 *      as published by the Free Software Foundation; either version
 *      2 of the License, or (at your option) any later version.
 *
 * Authors: Alexey Kuznetsov, <[email protected]>
 * Fixes:       19990609: J Hadi Salim <[email protected]>:
 *              Init --  EINVAL when opt undefined
 */

#include <linux/module.h>
#include <linux/slab.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/errno.h>
#include <linux/skbuff.h>
#include <net/netlink.h>
#include <net/pkt_sched.h>


struct prio_sched_data {
    int bands;
    struct tcf_proto *filter_list;
    u8  prio2band[TC_PRIO_MAX+1];
    struct Qdisc *queues[TCQ_PRIO_BANDS];
};


static struct Qdisc *
prio_classify(struct sk_buff *skb, struct Qdisc *sch, int *qerr)
{
    struct prio_sched_data *q = qdisc_priv(sch);
    u32 band = skb->priority;
    struct tcf_result res;
    int err;

    *qerr = NET_XMIT_SUCCESS | __NET_XMIT_BYPASS;
    if (TC_H_MAJ(skb->priority) != sch->handle) {
        err = tc_classify(skb, q->filter_list, &res);
#ifdef CONFIG_NET_CLS_ACT
        switch (err) {
        case TC_ACT_STOLEN:
        case TC_ACT_QUEUED:
            *qerr = NET_XMIT_SUCCESS | __NET_XMIT_STOLEN;
        case TC_ACT_SHOT:
            return NULL;
        }
#endif
        if (!q->filter_list || err < 0) {
            if (TC_H_MAJ(band))
                band = 0;
            return q->queues[q->prio2band[band & TC_PRIO_MAX]];
        }
        band = res.classid;
    }
    band = TC_H_MIN(band) - 1;
    if (band >= q->bands)
        return q->queues[q->prio2band[0]];

    return q->queues[band];
}

static int
prio_enqueue(struct sk_buff *skb, struct Qdisc *sch)
{
    struct Qdisc *qdisc;
    int ret;

    qdisc = prio_classify(skb, sch, &ret);
#ifdef CONFIG_NET_CLS_ACT
    if (qdisc == NULL) {

        if (ret & __NET_XMIT_BYPASS)
            sch->qstats.drops++;
        kfree_skb(skb);
        return ret;
    }
#endif

    ret = qdisc_enqueue(skb, qdisc);
    if (ret == NET_XMIT_SUCCESS) {
        sch->q.qlen++;
        return NET_XMIT_SUCCESS;
    }
    if (net_xmit_drop_count(ret))
        sch->qstats.drops++;
    return ret;
}

static struct sk_buff *prio_peek(struct Qdisc *sch)
{
    struct prio_sched_data *q = qdisc_priv(sch);
    int prio;

    for (prio = 0; prio < q->bands; prio++) {
        struct Qdisc *qdisc = q->queues[prio];
        struct sk_buff *skb = qdisc->ops->peek(qdisc);
        if (skb)
            return skb;
    }
    return NULL;
}

static struct sk_buff *prio_dequeue(struct Qdisc *sch)
{
    struct prio_sched_data *q = qdisc_priv(sch);
    int prio;

    for (prio = 0; prio < q->bands; prio++) {
        struct Qdisc *qdisc = q->queues[prio];
        struct sk_buff *skb = qdisc_dequeue_peeked(qdisc);
        if (skb) {
            qdisc_bstats_update(sch, skb);
            sch->q.qlen--;
            return skb;
        }
    }
    return NULL;

}

static unsigned int prio_drop(struct Qdisc *sch)
{
    struct prio_sched_data *q = qdisc_priv(sch);
    int prio;
    unsigned int len;
    struct Qdisc *qdisc;

    for (prio = q->bands-1; prio >= 0; prio--) {
        qdisc = q->queues[prio];
        if (qdisc->ops->drop && (len = qdisc->ops->drop(qdisc)) != 0) {
            sch->q.qlen--;
            return len;
        }
    }
    return 0;
}


static void
prio_reset(struct Qdisc *sch)
{
    int prio;
    struct prio_sched_data *q = qdisc_priv(sch);

    for (prio = 0; prio < q->bands; prio++)
        qdisc_reset(q->queues[prio]);
    sch->q.qlen = 0;
}

static void
prio_destroy(struct Qdisc *sch)
{
    int prio;
    struct prio_sched_data *q = qdisc_priv(sch);

    tcf_destroy_chain(&q->filter_list);
    for (prio = 0; prio < q->bands; prio++)
        qdisc_destroy(q->queues[prio]);
}

static int prio_tune(struct Qdisc *sch, struct nlattr *opt)
{
    struct prio_sched_data *q = qdisc_priv(sch);
    struct tc_prio_qopt *qopt;
    int i;

    if (nla_len(opt) < sizeof(*qopt))
        return -EINVAL;
    qopt = nla_data(opt);

    if (qopt->bands > TCQ_PRIO_BANDS || qopt->bands < 2)
        return -EINVAL;

    for (i = 0; i <= TC_PRIO_MAX; i++) {
        if (qopt->priomap[i] >= qopt->bands)
            return -EINVAL;
    }

    sch_tree_lock(sch);
    q->bands = qopt->bands;
    memcpy(q->prio2band, qopt->priomap, TC_PRIO_MAX+1);

    for (i = q->bands; i < TCQ_PRIO_BANDS; i++) {
        struct Qdisc *child = q->queues[i];
        q->queues[i] = &noop_qdisc;
        if (child != &noop_qdisc) {
            qdisc_tree_decrease_qlen(child, child->q.qlen);
            qdisc_destroy(child);
        }
    }
    sch_tree_unlock(sch);

    for (i = 0; i < q->bands; i++) {
        if (q->queues[i] == &noop_qdisc) {
            struct Qdisc *child, *old;

            child = qdisc_create_dflt(sch->dev_queue,
                          &pfifo_qdisc_ops,
                          TC_H_MAKE(sch->handle, i + 1));
            if (child) {
                sch_tree_lock(sch);
                old = q->queues[i];
                q->queues[i] = child;

                if (old != &noop_qdisc) {
                    qdisc_tree_decrease_qlen(old,
                                 old->q.qlen);
                    qdisc_destroy(old);
                }
                sch_tree_unlock(sch);
            }
        }
    }
    return 0;
}

static int prio_init(struct Qdisc *sch, struct nlattr *opt)
{
    struct prio_sched_data *q = qdisc_priv(sch);
    int i;

    for (i = 0; i < TCQ_PRIO_BANDS; i++)
        q->queues[i] = &noop_qdisc;

    if (opt == NULL) {
        return -EINVAL;
    } else {
        int err;

        if ((err = prio_tune(sch, opt)) != 0)
            return err;
    }
    return 0;
}

static int prio_dump(struct Qdisc *sch, struct sk_buff *skb)
{
    struct prio_sched_data *q = qdisc_priv(sch);
    unsigned char *b = skb_tail_pointer(skb);
    struct tc_prio_qopt opt;

    opt.bands = q->bands;
    memcpy(&opt.priomap, q->prio2band, TC_PRIO_MAX + 1);

    if (nla_put(skb, TCA_OPTIONS, sizeof(opt), &opt))
        goto nla_put_failure;

    return skb->len;

nla_put_failure:
    nlmsg_trim(skb, b);
    return -1;
}

static int prio_graft(struct Qdisc *sch, unsigned long arg, struct Qdisc *new,
              struct Qdisc **old)
{
    struct prio_sched_data *q = qdisc_priv(sch);
    unsigned long band = arg - 1;

    if (new == NULL)
        new = &noop_qdisc;

    sch_tree_lock(sch);
    *old = q->queues[band];
    q->queues[band] = new;
    qdisc_tree_decrease_qlen(*old, (*old)->q.qlen);
    qdisc_reset(*old);
    sch_tree_unlock(sch);

    return 0;
}

static struct Qdisc *
prio_leaf(struct Qdisc *sch, unsigned long arg)
{
    struct prio_sched_data *q = qdisc_priv(sch);
    unsigned long band = arg - 1;

    return q->queues[band];
}

static unsigned long prio_get(struct Qdisc *sch, u32 classid)
{
    struct prio_sched_data *q = qdisc_priv(sch);
    unsigned long band = TC_H_MIN(classid);

    if (band - 1 >= q->bands)
        return 0;
    return band;
}

static unsigned long prio_bind(struct Qdisc *sch, unsigned long parent, u32 classid)
{
    return prio_get(sch, classid);
}


static void prio_put(struct Qdisc *q, unsigned long cl)
{
}

static int prio_dump_class(struct Qdisc *sch, unsigned long cl, struct sk_buff *skb,
               struct tcmsg *tcm)
{
    struct prio_sched_data *q = qdisc_priv(sch);

    tcm->tcm_handle |= TC_H_MIN(cl);
    tcm->tcm_info = q->queues[cl-1]->handle;
    return 0;
}

static int prio_dump_class_stats(struct Qdisc *sch, unsigned long cl,
                 struct gnet_dump *d)
{
    struct prio_sched_data *q = qdisc_priv(sch);
    struct Qdisc *cl_q;

    cl_q = q->queues[cl - 1];
    cl_q->qstats.qlen = cl_q->q.qlen;
    if (gnet_stats_copy_basic(d, &cl_q->bstats) < 0 ||
        gnet_stats_copy_queue(d, &cl_q->qstats) < 0)
        return -1;

    return 0;
}

static void prio_walk(struct Qdisc *sch, struct qdisc_walker *arg)
{
    struct prio_sched_data *q = qdisc_priv(sch);
    int prio;

    if (arg->stop)
        return;

    for (prio = 0; prio < q->bands; prio++) {
        if (arg->count < arg->skip) {
            arg->count++;
            continue;
        }
        if (arg->fn(sch, prio + 1, arg) < 0) {
            arg->stop = 1;
            break;
        }
        arg->count++;
    }
}

static struct tcf_proto **prio_find_tcf(struct Qdisc *sch, unsigned long cl)
{
    struct prio_sched_data *q = qdisc_priv(sch);

    if (cl)
        return NULL;
    return &q->filter_list;
}

static const struct Qdisc_class_ops prio_class_ops = {
    .graft      =   prio_graft,
    .leaf       =   prio_leaf,
    .get        =   prio_get,
    .put        =   prio_put,
    .walk       =   prio_walk,
    .tcf_chain  =   prio_find_tcf,
    .bind_tcf   =   prio_bind,
    .unbind_tcf =   prio_put,
    .dump       =   prio_dump_class,
    .dump_stats =   prio_dump_class_stats,
};

static struct Qdisc_ops prio_qdisc_ops __read_mostly = {
    .next       =   NULL,
    .cl_ops     =   &prio_class_ops,
    .id     =   "prio",
    .priv_size  =   sizeof(struct prio_sched_data),
    .enqueue    =   prio_enqueue,
    .dequeue    =   prio_dequeue,
    .peek       =   prio_peek,
    .drop       =   prio_drop,
    .init       =   prio_init,
    .reset      =   prio_reset,
    .destroy    =   prio_destroy,
    .change     =   prio_tune,
    .dump       =   prio_dump,
    .owner      =   THIS_MODULE,
};

static int __init prio_module_init(void)
{
    return register_qdisc(&prio_qdisc_ops);
}

static void __exit prio_module_exit(void)
{
    unregister_qdisc(&prio_qdisc_ops);
}

module_init(prio_module_init)
module_exit(prio_module_exit)

MODULE_LICENSE("GPL");