48a8f519e0
From: Patrick McHardy <kaber@trash.net> Just as a demonstration how easy adding a peek operation to the work-conserving qdiscs actually is. It doesn't need to keep or change any internal state in many cases thanks to the guarantee that the packet will either be dequeued or, if another packet arrives, the upper qdisc will immediately ->peek again to reevaluate the state. (This is only slightly modified Patrick's patch.) Signed-off-by: Jarek Poplawski <jarkao2@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
155 lines
3.5 KiB
C
155 lines
3.5 KiB
C
/*
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* net/sched/sch_fifo.c The simplest FIFO 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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*/
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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/errno.h>
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#include <linux/skbuff.h>
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#include <net/pkt_sched.h>
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/* 1 band FIFO pseudo-"scheduler" */
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struct fifo_sched_data
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{
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u32 limit;
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};
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static int bfifo_enqueue(struct sk_buff *skb, struct Qdisc* sch)
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{
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struct fifo_sched_data *q = qdisc_priv(sch);
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if (likely(sch->qstats.backlog + qdisc_pkt_len(skb) <= q->limit))
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return qdisc_enqueue_tail(skb, sch);
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return qdisc_reshape_fail(skb, sch);
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}
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static int pfifo_enqueue(struct sk_buff *skb, struct Qdisc* sch)
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{
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struct fifo_sched_data *q = qdisc_priv(sch);
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if (likely(skb_queue_len(&sch->q) < q->limit))
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return qdisc_enqueue_tail(skb, sch);
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return qdisc_reshape_fail(skb, sch);
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}
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static int fifo_init(struct Qdisc *sch, struct nlattr *opt)
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{
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struct fifo_sched_data *q = qdisc_priv(sch);
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if (opt == NULL) {
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u32 limit = qdisc_dev(sch)->tx_queue_len ? : 1;
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if (sch->ops == &bfifo_qdisc_ops)
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limit *= qdisc_dev(sch)->mtu;
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q->limit = limit;
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} else {
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struct tc_fifo_qopt *ctl = nla_data(opt);
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if (nla_len(opt) < sizeof(*ctl))
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return -EINVAL;
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q->limit = ctl->limit;
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}
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return 0;
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}
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static int fifo_dump(struct Qdisc *sch, struct sk_buff *skb)
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{
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struct fifo_sched_data *q = qdisc_priv(sch);
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struct tc_fifo_qopt opt = { .limit = q->limit };
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NLA_PUT(skb, TCA_OPTIONS, sizeof(opt), &opt);
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return skb->len;
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nla_put_failure:
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return -1;
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}
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struct Qdisc_ops pfifo_qdisc_ops __read_mostly = {
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.id = "pfifo",
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.priv_size = sizeof(struct fifo_sched_data),
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.enqueue = pfifo_enqueue,
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.dequeue = qdisc_dequeue_head,
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.peek = qdisc_peek_head,
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.requeue = qdisc_requeue,
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.drop = qdisc_queue_drop,
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.init = fifo_init,
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.reset = qdisc_reset_queue,
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.change = fifo_init,
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.dump = fifo_dump,
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.owner = THIS_MODULE,
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};
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EXPORT_SYMBOL(pfifo_qdisc_ops);
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struct Qdisc_ops bfifo_qdisc_ops __read_mostly = {
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.id = "bfifo",
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.priv_size = sizeof(struct fifo_sched_data),
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.enqueue = bfifo_enqueue,
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.dequeue = qdisc_dequeue_head,
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.peek = qdisc_peek_head,
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.requeue = qdisc_requeue,
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.drop = qdisc_queue_drop,
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.init = fifo_init,
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.reset = qdisc_reset_queue,
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.change = fifo_init,
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.dump = fifo_dump,
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.owner = THIS_MODULE,
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};
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EXPORT_SYMBOL(bfifo_qdisc_ops);
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/* Pass size change message down to embedded FIFO */
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int fifo_set_limit(struct Qdisc *q, unsigned int limit)
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{
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struct nlattr *nla;
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int ret = -ENOMEM;
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/* Hack to avoid sending change message to non-FIFO */
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if (strncmp(q->ops->id + 1, "fifo", 4) != 0)
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return 0;
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nla = kmalloc(nla_attr_size(sizeof(struct tc_fifo_qopt)), GFP_KERNEL);
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if (nla) {
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nla->nla_type = RTM_NEWQDISC;
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nla->nla_len = nla_attr_size(sizeof(struct tc_fifo_qopt));
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((struct tc_fifo_qopt *)nla_data(nla))->limit = limit;
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ret = q->ops->change(q, nla);
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kfree(nla);
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}
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return ret;
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}
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EXPORT_SYMBOL(fifo_set_limit);
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struct Qdisc *fifo_create_dflt(struct Qdisc *sch, struct Qdisc_ops *ops,
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unsigned int limit)
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{
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struct Qdisc *q;
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int err = -ENOMEM;
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q = qdisc_create_dflt(qdisc_dev(sch), sch->dev_queue,
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ops, TC_H_MAKE(sch->handle, 1));
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if (q) {
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err = fifo_set_limit(q, limit);
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if (err < 0) {
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qdisc_destroy(q);
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q = NULL;
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}
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}
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return q ? : ERR_PTR(err);
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}
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EXPORT_SYMBOL(fifo_create_dflt);
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