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
bfifo_enqueue(struct sk_buff * skb,struct Qdisc * sch)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 + qdisc_pkt_len(skb) <= q->limit))
31 return qdisc_enqueue_tail(skb, sch);
32
33 return qdisc_reshape_fail(skb, sch);
34 }
35
pfifo_enqueue(struct sk_buff * skb,struct Qdisc * sch)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
fifo_init(struct Qdisc * sch,struct nlattr * opt)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 = 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
fifo_dump(struct Qdisc * sch,struct sk_buff * skb)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 .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 };
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 .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 };
109 EXPORT_SYMBOL(bfifo_qdisc_ops);
110
111 /* Pass size change message down to embedded FIFO */
fifo_set_limit(struct Qdisc * q,unsigned int limit)112 int 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 }
132 EXPORT_SYMBOL(fifo_set_limit);
133
fifo_create_dflt(struct Qdisc * sch,struct Qdisc_ops * ops,unsigned int limit)134 struct 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 }
152 EXPORT_SYMBOL(fifo_create_dflt);
153