2 * net/sched/sch_fifo.c The simplest FIFO queue.
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.
9 * Authors: Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
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>
19 /* 1 band FIFO pseudo-"scheduler" */
21 struct fifo_sched_data
26 static int bfifo_enqueue(struct sk_buff *skb, struct Qdisc* sch)
28 struct fifo_sched_data *q = qdisc_priv(sch);
30 if (likely(sch->qstats.backlog + qdisc_pkt_len(skb) <= q->limit))
31 return qdisc_enqueue_tail(skb, sch);
33 return qdisc_reshape_fail(skb, sch);
36 static int pfifo_enqueue(struct sk_buff *skb, struct Qdisc* sch)
38 struct fifo_sched_data *q = qdisc_priv(sch);
40 if (likely(skb_queue_len(&sch->q) < q->limit))
41 return qdisc_enqueue_tail(skb, sch);
43 return qdisc_reshape_fail(skb, sch);
46 static int fifo_init(struct Qdisc *sch, struct nlattr *opt)
48 struct fifo_sched_data *q = qdisc_priv(sch);
51 u32 limit = qdisc_dev(sch)->tx_queue_len ? : 1;
53 if (sch->ops == &bfifo_qdisc_ops)
54 limit *= psched_mtu(qdisc_dev(sch));
58 struct tc_fifo_qopt *ctl = nla_data(opt);
60 if (nla_len(opt) < sizeof(*ctl))
63 q->limit = ctl->limit;
69 static int fifo_dump(struct Qdisc *sch, struct sk_buff *skb)
71 struct fifo_sched_data *q = qdisc_priv(sch);
72 struct tc_fifo_qopt opt = { .limit = q->limit };
74 NLA_PUT(skb, TCA_OPTIONS, sizeof(opt), &opt);
81 struct Qdisc_ops pfifo_qdisc_ops __read_mostly = {
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,
89 .reset = qdisc_reset_queue,
94 EXPORT_SYMBOL(pfifo_qdisc_ops);
96 struct Qdisc_ops bfifo_qdisc_ops __read_mostly = {
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,
104 .reset = qdisc_reset_queue,
107 .owner = THIS_MODULE,
109 EXPORT_SYMBOL(bfifo_qdisc_ops);
111 /* Pass size change message down to embedded FIFO */
112 int fifo_set_limit(struct Qdisc *q, unsigned int limit)
117 /* Hack to avoid sending change message to non-FIFO */
118 if (strncmp(q->ops->id + 1, "fifo", 4) != 0)
121 nla = kmalloc(nla_attr_size(sizeof(struct tc_fifo_qopt)), GFP_KERNEL);
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;
127 ret = q->ops->change(q, nla);
132 EXPORT_SYMBOL(fifo_set_limit);
134 struct Qdisc *fifo_create_dflt(struct Qdisc *sch, struct Qdisc_ops *ops,
140 q = qdisc_create_dflt(qdisc_dev(sch), sch->dev_queue,
141 ops, TC_H_MAKE(sch->handle, 1));
143 err = fifo_set_limit(q, limit);
150 return q ? : ERR_PTR(err);
152 EXPORT_SYMBOL(fifo_create_dflt);