sch_mq.c

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/*
 * net/sched/sch_mq.c       Classful multiqueue dummy scheduler
 *
 * Copyright (c) 2009 Patrick McHardy <[email protected]>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * version 2 as published by the Free Software Foundation.
 */

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

struct mq_sched {
    struct Qdisc        **qdiscs;
};

static void mq_destroy(struct Qdisc *sch)
{
    struct net_device *dev = qdisc_dev(sch);
    struct mq_sched *priv = qdisc_priv(sch);
    unsigned int ntx;

    if (!priv->qdiscs)
        return;
    for (ntx = 0; ntx < dev->num_tx_queues && priv->qdiscs[ntx]; ntx++)
        qdisc_destroy(priv->qdiscs[ntx]);
    kfree(priv->qdiscs);
}

static int mq_init(struct Qdisc *sch, struct nlattr *opt)
{
    struct net_device *dev = qdisc_dev(sch);
    struct mq_sched *priv = qdisc_priv(sch);
    struct netdev_queue *dev_queue;
    struct Qdisc *qdisc;
    unsigned int ntx;

    if (sch->parent != TC_H_ROOT)
        return -EOPNOTSUPP;

    if (!netif_is_multiqueue(dev))
        return -EOPNOTSUPP;

    /* pre-allocate qdiscs, attachment can't fail */
    priv->qdiscs = kcalloc(dev->num_tx_queues, sizeof(priv->qdiscs[0]),
                   GFP_KERNEL);
    if (priv->qdiscs == NULL)
        return -ENOMEM;

    for (ntx = 0; ntx < dev->num_tx_queues; ntx++) {
        dev_queue = netdev_get_tx_queue(dev, ntx);
        qdisc = qdisc_create_dflt(dev_queue, &pfifo_fast_ops,
                      TC_H_MAKE(TC_H_MAJ(sch->handle),
                            TC_H_MIN(ntx + 1)));
        if (qdisc == NULL)
            goto err;
        priv->qdiscs[ntx] = qdisc;
    }

    sch->flags |= TCQ_F_MQROOT;
    return 0;

err:
    mq_destroy(sch);
    return -ENOMEM;
}

static void mq_attach(struct Qdisc *sch)
{
    struct net_device *dev = qdisc_dev(sch);
    struct mq_sched *priv = qdisc_priv(sch);
    struct Qdisc *qdisc;
    unsigned int ntx;

    for (ntx = 0; ntx < dev->num_tx_queues; ntx++) {
        qdisc = priv->qdiscs[ntx];
        qdisc = dev_graft_qdisc(qdisc->dev_queue, qdisc);
        if (qdisc)
            qdisc_destroy(qdisc);
    }
    kfree(priv->qdiscs);
    priv->qdiscs = NULL;
}

static int mq_dump(struct Qdisc *sch, struct sk_buff *skb)
{
    struct net_device *dev = qdisc_dev(sch);
    struct Qdisc *qdisc;
    unsigned int ntx;

    sch->q.qlen = 0;
    memset(&sch->bstats, 0, sizeof(sch->bstats));
    memset(&sch->qstats, 0, sizeof(sch->qstats));

    for (ntx = 0; ntx < dev->num_tx_queues; ntx++) {
        qdisc = netdev_get_tx_queue(dev, ntx)->qdisc_sleeping;
        spin_lock_bh(qdisc_lock(qdisc));
        sch->q.qlen     += qdisc->q.qlen;
        sch->bstats.bytes   += qdisc->bstats.bytes;
        sch->bstats.packets += qdisc->bstats.packets;
        sch->qstats.qlen    += qdisc->qstats.qlen;
        sch->qstats.backlog += qdisc->qstats.backlog;
        sch->qstats.drops   += qdisc->qstats.drops;
        sch->qstats.requeues    += qdisc->qstats.requeues;
        sch->qstats.overlimits  += qdisc->qstats.overlimits;
        spin_unlock_bh(qdisc_lock(qdisc));
    }
    return 0;
}

static struct netdev_queue *mq_queue_get(struct Qdisc *sch, unsigned long cl)
{
    struct net_device *dev = qdisc_dev(sch);
    unsigned long ntx = cl - 1;

    if (ntx >= dev->num_tx_queues)
        return NULL;
    return netdev_get_tx_queue(dev, ntx);
}

static struct netdev_queue *mq_select_queue(struct Qdisc *sch,
                        struct tcmsg *tcm)
{
    unsigned int ntx = TC_H_MIN(tcm->tcm_parent);
    struct netdev_queue *dev_queue = mq_queue_get(sch, ntx);

    if (!dev_queue) {
        struct net_device *dev = qdisc_dev(sch);

        return netdev_get_tx_queue(dev, 0);
    }
    return dev_queue;
}

static int mq_graft(struct Qdisc *sch, unsigned long cl, struct Qdisc *new,
            struct Qdisc **old)
{
    struct netdev_queue *dev_queue = mq_queue_get(sch, cl);
    struct net_device *dev = qdisc_dev(sch);

    if (dev->flags & IFF_UP)
        dev_deactivate(dev);

    *old = dev_graft_qdisc(dev_queue, new);

    if (dev->flags & IFF_UP)
        dev_activate(dev);
    return 0;
}

static struct Qdisc *mq_leaf(struct Qdisc *sch, unsigned long cl)
{
    struct netdev_queue *dev_queue = mq_queue_get(sch, cl);

    return dev_queue->qdisc_sleeping;
}

static unsigned long mq_get(struct Qdisc *sch, u32 classid)
{
    unsigned int ntx = TC_H_MIN(classid);

    if (!mq_queue_get(sch, ntx))
        return 0;
    return ntx;
}

static void mq_put(struct Qdisc *sch, unsigned long cl)
{
}

static int mq_dump_class(struct Qdisc *sch, unsigned long cl,
             struct sk_buff *skb, struct tcmsg *tcm)
{
    struct netdev_queue *dev_queue = mq_queue_get(sch, cl);

    tcm->tcm_parent = TC_H_ROOT;
    tcm->tcm_handle |= TC_H_MIN(cl);
    tcm->tcm_info = dev_queue->qdisc_sleeping->handle;
    return 0;
}

static int mq_dump_class_stats(struct Qdisc *sch, unsigned long cl,
                   struct gnet_dump *d)
{
    struct netdev_queue *dev_queue = mq_queue_get(sch, cl);

    sch = dev_queue->qdisc_sleeping;
    sch->qstats.qlen = sch->q.qlen;
    if (gnet_stats_copy_basic(d, &sch->bstats) < 0 ||
        gnet_stats_copy_queue(d, &sch->qstats) < 0)
        return -1;
    return 0;
}

static void mq_walk(struct Qdisc *sch, struct qdisc_walker *arg)
{
    struct net_device *dev = qdisc_dev(sch);
    unsigned int ntx;

    if (arg->stop)
        return;

    arg->count = arg->skip;
    for (ntx = arg->skip; ntx < dev->num_tx_queues; ntx++) {
        if (arg->fn(sch, ntx + 1, arg) < 0) {
            arg->stop = 1;
            break;
        }
        arg->count++;
    }
}

static const struct Qdisc_class_ops mq_class_ops = {
    .select_queue   = mq_select_queue,
    .graft      = mq_graft,
    .leaf       = mq_leaf,
    .get        = mq_get,
    .put        = mq_put,
    .walk       = mq_walk,
    .dump       = mq_dump_class,
    .dump_stats = mq_dump_class_stats,
};

struct Qdisc_ops mq_qdisc_ops __read_mostly = {
    .cl_ops     = &mq_class_ops,
    .id     = "mq",
    .priv_size  = sizeof(struct mq_sched),
    .init       = mq_init,
    .destroy    = mq_destroy,
    .attach     = mq_attach,
    .dump       = mq_dump,
    .owner      = THIS_MODULE,
};