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
22struct fifo_sched_data
23{
24	u32 limit;
25};
26
27static 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
37static 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
47static 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
70static 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
78rtattr_failure:
79	return -1;
80}
81
82struct 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
96struct 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
110EXPORT_SYMBOL(bfifo_qdisc_ops);
111EXPORT_SYMBOL(pfifo_qdisc_ops);
112