linux/net/sched/sch_fifo.c
<<
>>
Prefs
   1/*
   2 * net/sched/sch_fifo.c The simplest FIFO queue.
   3 *
   4 *              This program is free software; you can redistribute it and/or
   5 *              modify it under the terms of the GNU General Public License
   6 *              as published by the Free Software Foundation; either version
   7 *              2 of the License, or (at your option) any later version.
   8 *
   9 * Authors:     Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
  10 */
  11
  12#include <linux/module.h>
  13#include <linux/types.h>
  14#include <linux/kernel.h>
  15#include <linux/errno.h>
  16#include <linux/skbuff.h>
  17#include <net/pkt_sched.h>
  18
  19/* 1 band FIFO pseudo-"scheduler" */
  20
  21struct fifo_sched_data
  22{
  23        u32 limit;
  24};
  25
  26static int bfifo_enqueue(struct sk_buff *skb, struct Qdisc* sch)
  27{
  28        struct fifo_sched_data *q = qdisc_priv(sch);
  29
  30        if (likely(sch->qstats.backlog + qdisc_pkt_len(skb) <= q->limit))
  31                return qdisc_enqueue_tail(skb, sch);
  32
  33        return qdisc_reshape_fail(skb, sch);
  34}
  35
  36static int pfifo_enqueue(struct sk_buff *skb, struct Qdisc* sch)
  37{
  38        struct fifo_sched_data *q = qdisc_priv(sch);
  39
  40        if (likely(skb_queue_len(&sch->q) < q->limit))
  41                return qdisc_enqueue_tail(skb, sch);
  42
  43        return qdisc_reshape_fail(skb, sch);
  44}
  45
  46static int fifo_init(struct Qdisc *sch, struct nlattr *opt)
  47{
  48        struct fifo_sched_data *q = qdisc_priv(sch);
  49
  50        if (opt == NULL) {
  51                u32 limit = qdisc_dev(sch)->tx_queue_len ? : 1;
  52
  53                if (sch->ops == &bfifo_qdisc_ops)
  54                        limit *= qdisc_dev(sch)->mtu;
  55
  56                q->limit = limit;
  57        } else {
  58                struct tc_fifo_qopt *ctl = nla_data(opt);
  59
  60                if (nla_len(opt) < sizeof(*ctl))
  61                        return -EINVAL;
  62
  63                q->limit = ctl->limit;
  64        }
  65
  66        return 0;
  67}
  68
  69static int fifo_dump(struct Qdisc *sch, struct sk_buff *skb)
  70{
  71        struct fifo_sched_data *q = qdisc_priv(sch);
  72        struct tc_fifo_qopt opt = { .limit = q->limit };
  73
  74        NLA_PUT(skb, TCA_OPTIONS, sizeof(opt), &opt);
  75        return skb->len;
  76
  77nla_put_failure:
  78        return -1;
  79}
  80
  81struct Qdisc_ops pfifo_qdisc_ops __read_mostly = {
  82        .id             =       "pfifo",
  83        .priv_size      =       sizeof(struct fifo_sched_data),
  84        .enqueue        =       pfifo_enqueue,
  85        .dequeue        =       qdisc_dequeue_head,
  86        .peek           =       qdisc_peek_head,
  87        .drop           =       qdisc_queue_drop,
  88        .init           =       fifo_init,
  89        .reset          =       qdisc_reset_queue,
  90        .change         =       fifo_init,
  91        .dump           =       fifo_dump,
  92        .owner          =       THIS_MODULE,
  93};
  94EXPORT_SYMBOL(pfifo_qdisc_ops);
  95
  96struct Qdisc_ops bfifo_qdisc_ops __read_mostly = {
  97        .id             =       "bfifo",
  98        .priv_size      =       sizeof(struct fifo_sched_data),
  99        .enqueue        =       bfifo_enqueue,
 100        .dequeue        =       qdisc_dequeue_head,
 101        .peek           =       qdisc_peek_head,
 102        .drop           =       qdisc_queue_drop,
 103        .init           =       fifo_init,
 104        .reset          =       qdisc_reset_queue,
 105        .change         =       fifo_init,
 106        .dump           =       fifo_dump,
 107        .owner          =       THIS_MODULE,
 108};
 109EXPORT_SYMBOL(bfifo_qdisc_ops);
 110
 111/* Pass size change message down to embedded FIFO */
 112int fifo_set_limit(struct Qdisc *q, unsigned int limit)
 113{
 114        struct nlattr *nla;
 115        int ret = -ENOMEM;
 116
 117        /* Hack to avoid sending change message to non-FIFO */
 118        if (strncmp(q->ops->id + 1, "fifo", 4) != 0)
 119                return 0;
 120
 121        nla = kmalloc(nla_attr_size(sizeof(struct tc_fifo_qopt)), GFP_KERNEL);
 122        if (nla) {
 123                nla->nla_type = RTM_NEWQDISC;
 124                nla->nla_len = nla_attr_size(sizeof(struct tc_fifo_qopt));
 125                ((struct tc_fifo_qopt *)nla_data(nla))->limit = limit;
 126
 127                ret = q->ops->change(q, nla);
 128                kfree(nla);
 129        }
 130        return ret;
 131}
 132EXPORT_SYMBOL(fifo_set_limit);
 133
 134struct Qdisc *fifo_create_dflt(struct Qdisc *sch, struct Qdisc_ops *ops,
 135                               unsigned int limit)
 136{
 137        struct Qdisc *q;
 138        int err = -ENOMEM;
 139
 140        q = qdisc_create_dflt(qdisc_dev(sch), sch->dev_queue,
 141                              ops, TC_H_MAKE(sch->handle, 1));
 142        if (q) {
 143                err = fifo_set_limit(q, limit);
 144                if (err < 0) {
 145                        qdisc_destroy(q);
 146                        q = NULL;
 147                }
 148        }
 149
 150        return q ? : ERR_PTR(err);
 151}
 152EXPORT_SYMBOL(fifo_create_dflt);
 153