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
21 struct fifo_sched_data
22 {
23 u32 limit;
24 };
25
26 static 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 + skb->len <= q->limit))
31 return qdisc_enqueue_tail(skb, sch);
32
33 return qdisc_reshape_fail(skb, sch);
34 }
35
36 static 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
46 static 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 = sch->dev->tx_queue_len ? : 1;
52
53 if (sch->ops == &bfifo_qdisc_ops)
54 limit *= sch->dev->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
69 static 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
77 nla_put_failure:
78 return -1;
79 }
80
81 struct 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 .requeue = qdisc_requeue,
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 };
94 EXPORT_SYMBOL(pfifo_qdisc_ops);
95
96 struct 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 .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 EXPORT_SYMBOL(bfifo_qdisc_ops);
110
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