sch_multiq.c

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/*
 * Copyright (c) 2008, Intel Corporation.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program; if not, write to the Free Software Foundation, Inc., 59 Temple
 * Place - Suite 330, Boston, MA 02111-1307 USA.
 *
 * Author: Alexander Duyck <[email protected]>
 */

#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 multiq_sched_data {
    u16 bands;
    u16 max_bands;
    u16 curband;
    struct tcf_proto *filter_list;
    struct Qdisc **queues;
};


static struct Qdisc *
multiq_classify(struct sk_buff *skb, struct Qdisc *sch, int *qerr)
{
    struct multiq_sched_data *q = qdisc_priv(sch);
    u32 band;
    struct tcf_result res;
    int err;

    *qerr = NET_XMIT_SUCCESS | __NET_XMIT_BYPASS;
    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
    band = skb_get_queue_mapping(skb);

    if (band >= q->bands)
        return q->queues[0];

    return q->queues[band];
}

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

    qdisc = multiq_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 *multiq_dequeue(struct Qdisc *sch)
{
    struct multiq_sched_data *q = qdisc_priv(sch);
    struct Qdisc *qdisc;
    struct sk_buff *skb;
    int band;

    for (band = 0; band < q->bands; band++) {
        /* cycle through bands to ensure fairness */
        q->curband++;
        if (q->curband >= q->bands)
            q->curband = 0;

        /* Check that target subqueue is available before
         * pulling an skb to avoid head-of-line blocking.
         */
        if (!netif_xmit_stopped(
            netdev_get_tx_queue(qdisc_dev(sch), q->curband))) {
            qdisc = q->queues[q->curband];
            skb = qdisc->dequeue(qdisc);
            if (skb) {
                qdisc_bstats_update(sch, skb);
                sch->q.qlen--;
                return skb;
            }
        }
    }
    return NULL;

}

static struct sk_buff *multiq_peek(struct Qdisc *sch)
{
    struct multiq_sched_data *q = qdisc_priv(sch);
    unsigned int curband = q->curband;
    struct Qdisc *qdisc;
    struct sk_buff *skb;
    int band;

    for (band = 0; band < q->bands; band++) {
        /* cycle through bands to ensure fairness */
        curband++;
        if (curband >= q->bands)
            curband = 0;

        /* Check that target subqueue is available before
         * pulling an skb to avoid head-of-line blocking.
         */
        if (!netif_xmit_stopped(
            netdev_get_tx_queue(qdisc_dev(sch), curband))) {
            qdisc = q->queues[curband];
            skb = qdisc->ops->peek(qdisc);
            if (skb)
                return skb;
        }
    }
    return NULL;

}

static unsigned int multiq_drop(struct Qdisc *sch)
{
    struct multiq_sched_data *q = qdisc_priv(sch);
    int band;
    unsigned int len;
    struct Qdisc *qdisc;

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


static void
multiq_reset(struct Qdisc *sch)
{
    u16 band;
    struct multiq_sched_data *q = qdisc_priv(sch);

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

static void
multiq_destroy(struct Qdisc *sch)
{
    int band;
    struct multiq_sched_data *q = qdisc_priv(sch);

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

    kfree(q->queues);
}

static int multiq_tune(struct Qdisc *sch, struct nlattr *opt)
{
    struct multiq_sched_data *q = qdisc_priv(sch);
    struct tc_multiq_qopt *qopt;
    int i;

    if (!netif_is_multiqueue(qdisc_dev(sch)))
        return -EOPNOTSUPP;
    if (nla_len(opt) < sizeof(*qopt))
        return -EINVAL;

    qopt = nla_data(opt);

    qopt->bands = qdisc_dev(sch)->real_num_tx_queues;

    sch_tree_lock(sch);
    q->bands = qopt->bands;
    for (i = q->bands; i < q->max_bands; i++) {
        if (q->queues[i] != &noop_qdisc) {
            struct Qdisc *child = q->queues[i];
            q->queues[i] = &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 multiq_init(struct Qdisc *sch, struct nlattr *opt)
{
    struct multiq_sched_data *q = qdisc_priv(sch);
    int i, err;

    q->queues = NULL;

    if (opt == NULL)
        return -EINVAL;

    q->max_bands = qdisc_dev(sch)->num_tx_queues;

    q->queues = kcalloc(q->max_bands, sizeof(struct Qdisc *), GFP_KERNEL);
    if (!q->queues)
        return -ENOBUFS;
    for (i = 0; i < q->max_bands; i++)
        q->queues[i] = &noop_qdisc;

    err = multiq_tune(sch, opt);

    if (err)
        kfree(q->queues);

    return err;
}

static int multiq_dump(struct Qdisc *sch, struct sk_buff *skb)
{
    struct multiq_sched_data *q = qdisc_priv(sch);
    unsigned char *b = skb_tail_pointer(skb);
    struct tc_multiq_qopt opt;

    opt.bands = q->bands;
    opt.max_bands = q->max_bands;

    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 multiq_graft(struct Qdisc *sch, unsigned long arg, struct Qdisc *new,
              struct Qdisc **old)
{
    struct multiq_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 *
multiq_leaf(struct Qdisc *sch, unsigned long arg)
{
    struct multiq_sched_data *q = qdisc_priv(sch);
    unsigned long band = arg - 1;

    return q->queues[band];
}

static unsigned long multiq_get(struct Qdisc *sch, u32 classid)
{
    struct multiq_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 multiq_bind(struct Qdisc *sch, unsigned long parent,
                 u32 classid)
{
    return multiq_get(sch, classid);
}


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

static int multiq_dump_class(struct Qdisc *sch, unsigned long cl,
                 struct sk_buff *skb, struct tcmsg *tcm)
{
    struct multiq_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 multiq_dump_class_stats(struct Qdisc *sch, unsigned long cl,
                 struct gnet_dump *d)
{
    struct multiq_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 multiq_walk(struct Qdisc *sch, struct qdisc_walker *arg)
{
    struct multiq_sched_data *q = qdisc_priv(sch);
    int band;

    if (arg->stop)
        return;

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

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

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

static const struct Qdisc_class_ops multiq_class_ops = {
    .graft      =   multiq_graft,
    .leaf       =   multiq_leaf,
    .get        =   multiq_get,
    .put        =   multiq_put,
    .walk       =   multiq_walk,
    .tcf_chain  =   multiq_find_tcf,
    .bind_tcf   =   multiq_bind,
    .unbind_tcf =   multiq_put,
    .dump       =   multiq_dump_class,
    .dump_stats =   multiq_dump_class_stats,
};

static struct Qdisc_ops multiq_qdisc_ops __read_mostly = {
    .next       =   NULL,
    .cl_ops     =   &multiq_class_ops,
    .id     =   "multiq",
    .priv_size  =   sizeof(struct multiq_sched_data),
    .enqueue    =   multiq_enqueue,
    .dequeue    =   multiq_dequeue,
    .peek       =   multiq_peek,
    .drop       =   multiq_drop,
    .init       =   multiq_init,
    .reset      =   multiq_reset,
    .destroy    =   multiq_destroy,
    .change     =   multiq_tune,
    .dump       =   multiq_dump,
    .owner      =   THIS_MODULE,
};

static int __init multiq_module_init(void)
{
    return register_qdisc(&multiq_qdisc_ops);
}

static void __exit multiq_module_exit(void)
{
    unregister_qdisc(&multiq_qdisc_ops);
}

module_init(multiq_module_init)
module_exit(multiq_module_exit)

MODULE_LICENSE("GPL");