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![Ilpo Järvinen](/assets/img/avatar_default.png)
tcp_sack_swap seems unnecessary so I pushed swap to the caller. Also removed comment that seemed then pointless, and added include when not already there. Compile tested. Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi> Signed-off-by: David S. Miller <davem@davemloft.net>
482 lines
11 KiB
C
482 lines
11 KiB
C
/*
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* net/sched/sch_tbf.c Token Bucket Filter queue.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*
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* Authors: Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
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* Dmitry Torokhov <dtor@mail.ru> - allow attaching inner qdiscs -
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* original idea by Martin Devera
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*
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*/
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#include <linux/module.h>
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#include <linux/types.h>
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#include <linux/kernel.h>
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#include <linux/string.h>
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#include <linux/errno.h>
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#include <linux/skbuff.h>
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#include <net/netlink.h>
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#include <net/pkt_sched.h>
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/* Simple Token Bucket Filter.
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=======================================
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SOURCE.
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-------
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None.
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Description.
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------------
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A data flow obeys TBF with rate R and depth B, if for any
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time interval t_i...t_f the number of transmitted bits
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does not exceed B + R*(t_f-t_i).
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Packetized version of this definition:
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The sequence of packets of sizes s_i served at moments t_i
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obeys TBF, if for any i<=k:
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s_i+....+s_k <= B + R*(t_k - t_i)
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Algorithm.
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----------
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Let N(t_i) be B/R initially and N(t) grow continuously with time as:
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N(t+delta) = min{B/R, N(t) + delta}
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If the first packet in queue has length S, it may be
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transmitted only at the time t_* when S/R <= N(t_*),
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and in this case N(t) jumps:
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N(t_* + 0) = N(t_* - 0) - S/R.
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Actually, QoS requires two TBF to be applied to a data stream.
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One of them controls steady state burst size, another
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one with rate P (peak rate) and depth M (equal to link MTU)
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limits bursts at a smaller time scale.
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It is easy to see that P>R, and B>M. If P is infinity, this double
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TBF is equivalent to a single one.
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When TBF works in reshaping mode, latency is estimated as:
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lat = max ((L-B)/R, (L-M)/P)
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NOTES.
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------
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If TBF throttles, it starts a watchdog timer, which will wake it up
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when it is ready to transmit.
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Note that the minimal timer resolution is 1/HZ.
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If no new packets arrive during this period,
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or if the device is not awaken by EOI for some previous packet,
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TBF can stop its activity for 1/HZ.
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This means, that with depth B, the maximal rate is
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R_crit = B*HZ
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F.e. for 10Mbit ethernet and HZ=100 the minimal allowed B is ~10Kbytes.
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Note that the peak rate TBF is much more tough: with MTU 1500
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P_crit = 150Kbytes/sec. So, if you need greater peak
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rates, use alpha with HZ=1000 :-)
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With classful TBF, limit is just kept for backwards compatibility.
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It is passed to the default bfifo qdisc - if the inner qdisc is
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changed the limit is not effective anymore.
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*/
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struct tbf_sched_data
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{
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/* Parameters */
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u32 limit; /* Maximal length of backlog: bytes */
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u32 buffer; /* Token bucket depth/rate: MUST BE >= MTU/B */
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u32 mtu;
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u32 max_size;
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struct qdisc_rate_table *R_tab;
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struct qdisc_rate_table *P_tab;
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/* Variables */
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long tokens; /* Current number of B tokens */
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long ptokens; /* Current number of P tokens */
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psched_time_t t_c; /* Time check-point */
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struct Qdisc *qdisc; /* Inner qdisc, default - bfifo queue */
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struct qdisc_watchdog watchdog; /* Watchdog timer */
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};
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#define L2T(q,L) qdisc_l2t((q)->R_tab,L)
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#define L2T_P(q,L) qdisc_l2t((q)->P_tab,L)
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static int tbf_enqueue(struct sk_buff *skb, struct Qdisc* sch)
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{
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struct tbf_sched_data *q = qdisc_priv(sch);
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int ret;
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if (qdisc_pkt_len(skb) > q->max_size)
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return qdisc_reshape_fail(skb, sch);
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ret = qdisc_enqueue(skb, q->qdisc);
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if (ret != 0) {
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if (net_xmit_drop_count(ret))
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sch->qstats.drops++;
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return ret;
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}
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sch->q.qlen++;
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sch->bstats.bytes += qdisc_pkt_len(skb);
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sch->bstats.packets++;
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return 0;
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}
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static unsigned int tbf_drop(struct Qdisc* sch)
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{
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struct tbf_sched_data *q = qdisc_priv(sch);
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unsigned int len = 0;
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if (q->qdisc->ops->drop && (len = q->qdisc->ops->drop(q->qdisc)) != 0) {
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sch->q.qlen--;
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sch->qstats.drops++;
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}
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return len;
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}
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static struct sk_buff *tbf_dequeue(struct Qdisc* sch)
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{
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struct tbf_sched_data *q = qdisc_priv(sch);
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struct sk_buff *skb;
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skb = q->qdisc->ops->peek(q->qdisc);
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if (skb) {
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psched_time_t now;
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long toks;
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long ptoks = 0;
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unsigned int len = qdisc_pkt_len(skb);
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now = psched_get_time();
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toks = psched_tdiff_bounded(now, q->t_c, q->buffer);
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if (q->P_tab) {
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ptoks = toks + q->ptokens;
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if (ptoks > (long)q->mtu)
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ptoks = q->mtu;
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ptoks -= L2T_P(q, len);
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}
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toks += q->tokens;
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if (toks > (long)q->buffer)
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toks = q->buffer;
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toks -= L2T(q, len);
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if ((toks|ptoks) >= 0) {
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skb = qdisc_dequeue_peeked(q->qdisc);
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if (unlikely(!skb))
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return NULL;
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q->t_c = now;
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q->tokens = toks;
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q->ptokens = ptoks;
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sch->q.qlen--;
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sch->flags &= ~TCQ_F_THROTTLED;
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return skb;
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}
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qdisc_watchdog_schedule(&q->watchdog,
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now + max_t(long, -toks, -ptoks));
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/* Maybe we have a shorter packet in the queue,
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which can be sent now. It sounds cool,
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but, however, this is wrong in principle.
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We MUST NOT reorder packets under these circumstances.
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Really, if we split the flow into independent
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subflows, it would be a very good solution.
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This is the main idea of all FQ algorithms
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(cf. CSZ, HPFQ, HFSC)
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*/
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sch->qstats.overlimits++;
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}
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return NULL;
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}
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static void tbf_reset(struct Qdisc* sch)
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{
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struct tbf_sched_data *q = qdisc_priv(sch);
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qdisc_reset(q->qdisc);
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sch->q.qlen = 0;
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q->t_c = psched_get_time();
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q->tokens = q->buffer;
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q->ptokens = q->mtu;
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qdisc_watchdog_cancel(&q->watchdog);
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}
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static const struct nla_policy tbf_policy[TCA_TBF_MAX + 1] = {
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[TCA_TBF_PARMS] = { .len = sizeof(struct tc_tbf_qopt) },
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[TCA_TBF_RTAB] = { .type = NLA_BINARY, .len = TC_RTAB_SIZE },
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[TCA_TBF_PTAB] = { .type = NLA_BINARY, .len = TC_RTAB_SIZE },
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};
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static int tbf_change(struct Qdisc* sch, struct nlattr *opt)
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{
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int err;
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struct tbf_sched_data *q = qdisc_priv(sch);
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struct nlattr *tb[TCA_TBF_PTAB + 1];
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struct tc_tbf_qopt *qopt;
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struct qdisc_rate_table *rtab = NULL;
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struct qdisc_rate_table *ptab = NULL;
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struct Qdisc *child = NULL;
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int max_size,n;
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err = nla_parse_nested(tb, TCA_TBF_PTAB, opt, tbf_policy);
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if (err < 0)
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return err;
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err = -EINVAL;
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if (tb[TCA_TBF_PARMS] == NULL)
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goto done;
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qopt = nla_data(tb[TCA_TBF_PARMS]);
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rtab = qdisc_get_rtab(&qopt->rate, tb[TCA_TBF_RTAB]);
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if (rtab == NULL)
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goto done;
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if (qopt->peakrate.rate) {
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if (qopt->peakrate.rate > qopt->rate.rate)
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ptab = qdisc_get_rtab(&qopt->peakrate, tb[TCA_TBF_PTAB]);
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if (ptab == NULL)
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goto done;
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}
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for (n = 0; n < 256; n++)
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if (rtab->data[n] > qopt->buffer) break;
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max_size = (n << qopt->rate.cell_log)-1;
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if (ptab) {
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int size;
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for (n = 0; n < 256; n++)
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if (ptab->data[n] > qopt->mtu) break;
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size = (n << qopt->peakrate.cell_log)-1;
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if (size < max_size) max_size = size;
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}
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if (max_size < 0)
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goto done;
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if (qopt->limit > 0) {
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child = fifo_create_dflt(sch, &bfifo_qdisc_ops, qopt->limit);
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if (IS_ERR(child)) {
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err = PTR_ERR(child);
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goto done;
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}
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}
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sch_tree_lock(sch);
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if (child) {
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qdisc_tree_decrease_qlen(q->qdisc, q->qdisc->q.qlen);
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qdisc_destroy(q->qdisc);
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q->qdisc = child;
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}
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q->limit = qopt->limit;
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q->mtu = qopt->mtu;
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q->max_size = max_size;
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q->buffer = qopt->buffer;
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q->tokens = q->buffer;
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q->ptokens = q->mtu;
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swap(q->R_tab, rtab);
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swap(q->P_tab, ptab);
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sch_tree_unlock(sch);
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err = 0;
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done:
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if (rtab)
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qdisc_put_rtab(rtab);
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if (ptab)
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qdisc_put_rtab(ptab);
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return err;
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}
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static int tbf_init(struct Qdisc* sch, struct nlattr *opt)
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{
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struct tbf_sched_data *q = qdisc_priv(sch);
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if (opt == NULL)
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return -EINVAL;
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q->t_c = psched_get_time();
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qdisc_watchdog_init(&q->watchdog, sch);
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q->qdisc = &noop_qdisc;
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return tbf_change(sch, opt);
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}
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static void tbf_destroy(struct Qdisc *sch)
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{
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struct tbf_sched_data *q = qdisc_priv(sch);
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qdisc_watchdog_cancel(&q->watchdog);
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if (q->P_tab)
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qdisc_put_rtab(q->P_tab);
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if (q->R_tab)
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qdisc_put_rtab(q->R_tab);
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qdisc_destroy(q->qdisc);
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}
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static int tbf_dump(struct Qdisc *sch, struct sk_buff *skb)
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{
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struct tbf_sched_data *q = qdisc_priv(sch);
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struct nlattr *nest;
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struct tc_tbf_qopt opt;
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nest = nla_nest_start(skb, TCA_OPTIONS);
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if (nest == NULL)
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goto nla_put_failure;
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opt.limit = q->limit;
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opt.rate = q->R_tab->rate;
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if (q->P_tab)
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opt.peakrate = q->P_tab->rate;
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else
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memset(&opt.peakrate, 0, sizeof(opt.peakrate));
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opt.mtu = q->mtu;
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opt.buffer = q->buffer;
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NLA_PUT(skb, TCA_TBF_PARMS, sizeof(opt), &opt);
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nla_nest_end(skb, nest);
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return skb->len;
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nla_put_failure:
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nla_nest_cancel(skb, nest);
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return -1;
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}
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static int tbf_dump_class(struct Qdisc *sch, unsigned long cl,
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struct sk_buff *skb, struct tcmsg *tcm)
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{
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struct tbf_sched_data *q = qdisc_priv(sch);
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if (cl != 1) /* only one class */
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return -ENOENT;
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tcm->tcm_handle |= TC_H_MIN(1);
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tcm->tcm_info = q->qdisc->handle;
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return 0;
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}
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static int tbf_graft(struct Qdisc *sch, unsigned long arg, struct Qdisc *new,
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struct Qdisc **old)
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{
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struct tbf_sched_data *q = qdisc_priv(sch);
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if (new == NULL)
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new = &noop_qdisc;
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sch_tree_lock(sch);
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*old = q->qdisc;
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q->qdisc = new;
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qdisc_tree_decrease_qlen(*old, (*old)->q.qlen);
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qdisc_reset(*old);
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sch_tree_unlock(sch);
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return 0;
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}
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static struct Qdisc *tbf_leaf(struct Qdisc *sch, unsigned long arg)
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{
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struct tbf_sched_data *q = qdisc_priv(sch);
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return q->qdisc;
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}
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static unsigned long tbf_get(struct Qdisc *sch, u32 classid)
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{
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return 1;
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}
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static void tbf_put(struct Qdisc *sch, unsigned long arg)
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{
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}
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static int tbf_change_class(struct Qdisc *sch, u32 classid, u32 parentid,
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struct nlattr **tca, unsigned long *arg)
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{
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return -ENOSYS;
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}
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static int tbf_delete(struct Qdisc *sch, unsigned long arg)
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{
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return -ENOSYS;
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}
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static void tbf_walk(struct Qdisc *sch, struct qdisc_walker *walker)
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{
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if (!walker->stop) {
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if (walker->count >= walker->skip)
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if (walker->fn(sch, 1, walker) < 0) {
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walker->stop = 1;
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return;
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}
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walker->count++;
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}
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}
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static struct tcf_proto **tbf_find_tcf(struct Qdisc *sch, unsigned long cl)
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{
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return NULL;
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}
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static const struct Qdisc_class_ops tbf_class_ops =
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{
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.graft = tbf_graft,
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.leaf = tbf_leaf,
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.get = tbf_get,
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.put = tbf_put,
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.change = tbf_change_class,
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.delete = tbf_delete,
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.walk = tbf_walk,
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.tcf_chain = tbf_find_tcf,
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.dump = tbf_dump_class,
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};
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static struct Qdisc_ops tbf_qdisc_ops __read_mostly = {
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.next = NULL,
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.cl_ops = &tbf_class_ops,
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.id = "tbf",
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.priv_size = sizeof(struct tbf_sched_data),
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.enqueue = tbf_enqueue,
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.dequeue = tbf_dequeue,
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.peek = qdisc_peek_dequeued,
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.drop = tbf_drop,
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.init = tbf_init,
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.reset = tbf_reset,
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.destroy = tbf_destroy,
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.change = tbf_change,
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.dump = tbf_dump,
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.owner = THIS_MODULE,
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};
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static int __init tbf_module_init(void)
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{
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return register_qdisc(&tbf_qdisc_ops);
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}
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static void __exit tbf_module_exit(void)
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{
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unregister_qdisc(&tbf_qdisc_ops);
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}
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module_init(tbf_module_init)
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module_exit(tbf_module_exit)
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MODULE_LICENSE("GPL");
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