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/*

 * net/sched/sch_delay.c        Simple constant delay

 *

 *              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:     Stephen Hemminger <shemminger@osdl.org>

 */

#include <linux/config.h>

#include <linux/module.h>

#include <linux/types.h>

#include <linux/kernel.h>

#include <linux/string.h>

#include <linux/mm.h>

#include <linux/socket.h>

#include <linux/sockios.h>

#include <linux/in.h>

#include <linux/errno.h>

#include <linux/interrupt.h>

#include <linux/if_ether.h>

#include <linux/inet.h>

#include <linux/netdevice.h>

#include <linux/etherdevice.h>

#include <linux/notifier.h>

#include <net/ip.h>

#include <net/route.h>

#include <linux/skbuff.h>

#include <net/sock.h>

#include <net/pkt_sched.h>

/*      Network delay simulator

        This scheduler adds a fixed delay to all packets.

        Similar to NISTnet and BSD Dummynet.

        It uses byte fifo underneath similar to TBF */

struct dly_sched_data {

        u32     latency;

        u32     limit;

        struct timer_list timer;

        struct Qdisc *qdisc;

};

/* Time stamp put into socket buffer control block */

struct dly_skb_cb {

        psched_time_t   queuetime;

};

/* Enqueue packets with underlying discipline (fifo)

 * but mark them with current time first.

 */

static int dly_enqueue(struct sk_buff *skb, struct Qdisc *sch)

{

        struct dly_sched_data *q = (struct dly_sched_data *)sch->data;

        struct dly_skb_cb *cb = (struct dly_skb_cb *)skb->cb;

        int ret;

        PSCHED_GET_TIME(cb->queuetime);

        /* Queue to underlying scheduler */

        ret = q->qdisc->enqueue(skb, q->qdisc);

        if (ret)

                sch->stats.drops++;

        else {

                sch->q.qlen++;

                sch->stats.bytes += skb->len;

                sch->stats.packets++;

        }

        return 0;

}

/* Requeue packets but don't change time stamp */

static int dly_requeue(struct sk_buff *skb, struct Qdisc *sch)

{

        struct dly_sched_data *q = (struct dly_sched_data *)sch->data;

        int ret;

        ret = q->qdisc->ops->requeue(skb, q->qdisc);

        if (ret == 0)

                sch->q.qlen++;

        return ret;

}

static unsigned int dly_drop(struct Qdisc *sch)

{

        struct dly_sched_data *q = (struct dly_sched_data *)sch->data;

        unsigned int len;

        len = q->qdisc->ops->drop(q->qdisc);

        if (len) {

                sch->q.qlen--;

                sch->stats.drops++;

        }

        return len;

}

/* Dequeue packet.

 * If packet needs to be held up, then stop the

 * queue and set timer to wakeup later.

 */

static struct sk_buff *dly_dequeue(struct Qdisc *sch)

{

        struct dly_sched_data *q = (struct dly_sched_data *)sch->data;

        struct sk_buff *skb = q->qdisc->dequeue(q->qdisc);

        if (skb) {

                struct dly_skb_cb *cb = (struct dly_skb_cb *)skb->cb;

                psched_time_t now;

                long diff;

                PSCHED_GET_TIME(now);

                diff = q->latency - PSCHED_TDIFF(now, cb->queuetime);

                if (diff <= 0) {

                        sch->q.qlen--;

                        sch->flags &= ~TCQ_F_THROTTLED;

                        return skb;

                }

                if (!netif_queue_stopped(sch->dev)) {

                        long delay = PSCHED_US2JIFFIE(diff);

                        if (delay <= 0)

                                delay = 1;

                        mod_timer(&q->timer, jiffies+delay);

                }

                if (q->qdisc->ops->requeue(skb, q->qdisc) != NET_XMIT_SUCCESS) {

                        sch->q.qlen--;

                        sch->stats.drops++;

                }

                sch->flags |= TCQ_F_THROTTLED;

        }

        return NULL;

}

static void dly_reset(struct Qdisc *sch)

{

        struct dly_sched_data *q = (struct dly_sched_data *)sch->data;

        qdisc_reset(q->qdisc);

        sch->q.qlen = 0;

        sch->flags &= ~TCQ_F_THROTTLED;

        del_timer(&q->timer);

}

static void dly_timer(unsigned long arg)

{

        struct Qdisc *sch = (struct Qdisc *)arg;

        sch->flags &= ~TCQ_F_THROTTLED;

        netif_schedule(sch->dev);

}

/* Tell Fifo the new limit. */

static int change_limit(struct Qdisc *q, u32 limit)

{

        struct rtattr *rta;

        int ret;

        rta = kmalloc(RTA_LENGTH(sizeof(struct tc_fifo_qopt)), GFP_KERNEL);

        if (!rta)

                return -ENOMEM;

        rta->rta_type = RTM_NEWQDISC;

        ((struct tc_fifo_qopt *)RTA_DATA(rta))->limit = limit;

        ret = q->ops->change(q, rta);

        kfree(rta);

        return ret;

}

/* Setup underlying FIFO discipline */

static int dly_change(struct Qdisc *sch, struct rtattr *opt)

{

        struct dly_sched_data *q = (struct dly_sched_data *)sch->data;

        struct tc_dly_qopt *qopt = RTA_DATA(opt);

        int err;

        if (q->qdisc == &noop_qdisc) {

                struct Qdisc *child

                        = qdisc_create_dflt(sch->dev, &bfifo_qdisc_ops);

                if (!child)

                        return -EINVAL;

                q->qdisc = child;

        }

        err = change_limit(q->qdisc, qopt->limit);

        if (err) {

                qdisc_destroy(q->qdisc);

                q->qdisc = &noop_qdisc;

        } else {

                q->latency = qopt->latency;

                q->limit = qopt->limit;

        }

        return err;

}

static int dly_init(struct Qdisc *sch, struct rtattr *opt)

{

        struct dly_sched_data *q = (struct dly_sched_data *)sch->data;

        int err;

        if (!opt)

                return -EINVAL;

        MOD_INC_USE_COUNT;

        init_timer(&q->timer);

        q->timer.function = dly_timer;

        q->timer.data = (unsigned long) sch;

        q->qdisc = &noop_qdisc;

        err = dly_change(sch, opt);

        if (err)

                MOD_DEC_USE_COUNT;

        return err;

}

static void dly_destroy(struct Qdisc *sch)

{

        struct dly_sched_data *q = (struct dly_sched_data *)sch->data;

        del_timer(&q->timer);

        qdisc_destroy(q->qdisc);

        q->qdisc = &noop_qdisc;

        MOD_DEC_USE_COUNT;

}

static int dly_dump(struct Qdisc *sch, struct sk_buff *skb)

{

        struct dly_sched_data *q = (struct dly_sched_data *)sch->data;

        unsigned char    *b = skb->tail;

        struct tc_dly_qopt qopt;

        qopt.latency = q->latency;

        qopt.limit = q->limit;

        RTA_PUT(skb, TCA_OPTIONS, sizeof(qopt), &qopt);

        return skb->len;

rtattr_failure:

        skb_trim(skb, b - skb->data);

        return -1;

}

struct Qdisc_ops dly_qdisc_ops = {

        .id             =       "delay",

        .priv_size      =       sizeof(struct dly_sched_data),

        .enqueue        =       dly_enqueue,

        .dequeue        =       dly_dequeue,

        .requeue        =       dly_requeue,

        .drop           =       dly_drop,

        .init           =       dly_init,

        .reset          =       dly_reset,

        .destroy        =       dly_destroy,

        .change         =       dly_change,

        .dump           =       dly_dump,

};

#ifdef MODULE

int init_module(void)

{

        return register_qdisc(&dly_qdisc_ops);

}

void cleanup_module(void)

{

        unregister_qdisc(&dly_qdisc_ops);

}

#endif

MODULE_LICENSE("GPL");