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