net/sched/sch_fifo.c

   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/config.h>
  13 #include <linux/module.h>
  14 #include <linux/types.h>
  15 #include <linux/kernel.h>
  16 #include <linux/errno.h>
  17 #include <linux/netdevice.h>
  18 #include <linux/skbuff.h>
  19 #include <net/pkt_sched.h>
  20
  21 /* 1 band FIFO pseudo-"scheduler" */
  22
  23 struct fifo_sched_data
  24 {
  25         u32 limit;
  26 };
  27
  28 static int bfifo_enqueue(struct sk_buff *skb, struct Qdisc* sch)
  29 {
  30         struct fifo_sched_data *q = qdisc_priv(sch);
  31
  32         if (likely(sch->qstats.backlog + skb->len <= q->limit))
  33                 return qdisc_enqueue_tail(skb, sch);
  34
  35         return qdisc_reshape_fail(skb, sch);
  36 }
  37
  38 static int pfifo_enqueue(struct sk_buff *skb, struct Qdisc* sch)
  39 {
  40         struct fifo_sched_data *q = qdisc_priv(sch);
  41
  42         if (likely(skb_queue_len(&sch->q) < q->limit))
  43                 return qdisc_enqueue_tail(skb, sch);
  44
  45         return qdisc_reshape_fail(skb, sch);
  46 }
  47
  48 static int fifo_init(struct Qdisc *sch, struct rtattr *opt)
  49 {
  50         struct fifo_sched_data *q = qdisc_priv(sch);
  51
  52         if (opt == NULL) {
  53                 u32 limit = sch->dev->tx_queue_len ? : 1;
  54
  55                 if (sch->ops == &bfifo_qdisc_ops)
  56                         limit *= sch->dev->mtu;
  57
  58                 q->limit = limit;
  59         } else {
  60                 struct tc_fifo_qopt *ctl = RTA_DATA(opt);
  61
  62                 if (RTA_PAYLOAD(opt) < sizeof(*ctl))
  63                         return -EINVAL;
  64
  65                 q->limit = ctl->limit;
  66         }
  67
  68         return 0;
  69 }
  70
  71 static int fifo_dump(struct Qdisc *sch, struct sk_buff *skb)
  72 {
  73         struct fifo_sched_data *q = qdisc_priv(sch);
  74         struct tc_fifo_qopt opt = { .limit = q->limit };
  75
  76         RTA_PUT(skb, TCA_OPTIONS, sizeof(opt), &opt);
  77         return skb->len;
  78
  79 rtattr_failure:
  80         return -1;
  81 }
  82
  83 struct Qdisc_ops pfifo_qdisc_ops = {
  84         .id             =       "pfifo",
  85         .priv_size      =       sizeof(struct fifo_sched_data),
  86         .enqueue        =       pfifo_enqueue,
  87         .dequeue        =       qdisc_dequeue_head,
  88         .requeue        =       qdisc_requeue,
  89         .drop           =       qdisc_queue_drop,
  90         .init           =       fifo_init,
  91         .reset          =       qdisc_reset_queue,
  92         .change         =       fifo_init,
  93         .dump           =       fifo_dump,
  94         .owner          =       THIS_MODULE,
  95 };
  96
  97 struct Qdisc_ops bfifo_qdisc_ops = {
  98         .id             =       "bfifo",
  99         .priv_size      =       sizeof(struct fifo_sched_data),
 100         .enqueue        =       bfifo_enqueue,
 101         .dequeue        =       qdisc_dequeue_head,
 102         .requeue        =       qdisc_requeue,
 103         .drop           =       qdisc_queue_drop,
 104         .init           =       fifo_init,
 105         .reset          =       qdisc_reset_queue,
 106         .change         =       fifo_init,
 107         .dump           =       fifo_dump,
 108         .owner          =       THIS_MODULE,
 109 };
 110
 111 EXPORT_SYMBOL(bfifo_qdisc_ops);
 112 EXPORT_SYMBOL(pfifo_qdisc_ops);