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/slab.h>
14 #include <linux/types.h>
15 #include <linux/kernel.h>
16 #include <linux/errno.h>
17 #include <linux/skbuff.h>
18 #include <net/pkt_sched.h>
20 /* 1 band FIFO pseudo-"scheduler" */
22 struct fifo_sched_data
27 static int bfifo_enqueue(struct sk_buff *skb, struct Qdisc* sch)
29 struct fifo_sched_data *q = qdisc_priv(sch);
31 if (likely(sch->qstats.backlog + qdisc_pkt_len(skb) <= q->limit))
32 return qdisc_enqueue_tail(skb, sch);
34 return qdisc_reshape_fail(skb, sch);
37 static int pfifo_enqueue(struct sk_buff *skb, struct Qdisc* sch)
39 struct fifo_sched_data *q = qdisc_priv(sch);
41 if (likely(skb_queue_len(&sch->q) < q->limit))
42 return qdisc_enqueue_tail(skb, sch);
44 return qdisc_reshape_fail(skb, sch);
47 static int pfifo_tail_enqueue(struct sk_buff *skb, struct Qdisc* sch)
49 struct fifo_sched_data *q = qdisc_priv(sch);
51 if (likely(skb_queue_len(&sch->q) < q->limit))
52 return qdisc_enqueue_tail(skb, sch);
54 /* queue full, remove one skb to fulfill the limit */
55 __qdisc_queue_drop_head(sch, &sch->q);
57 qdisc_enqueue_tail(skb, sch);
62 static int fifo_init(struct Qdisc *sch, struct nlattr *opt)
64 struct fifo_sched_data *q = qdisc_priv(sch);
67 u32 limit = qdisc_dev(sch)->tx_queue_len ? : 1;
69 if (sch->ops == &bfifo_qdisc_ops)
70 limit *= psched_mtu(qdisc_dev(sch));
74 struct tc_fifo_qopt *ctl = nla_data(opt);
76 if (nla_len(opt) < sizeof(*ctl))
79 q->limit = ctl->limit;
85 static int fifo_dump(struct Qdisc *sch, struct sk_buff *skb)
87 struct fifo_sched_data *q = qdisc_priv(sch);
88 struct tc_fifo_qopt opt = { .limit = q->limit };
90 NLA_PUT(skb, TCA_OPTIONS, sizeof(opt), &opt);
97 struct Qdisc_ops pfifo_qdisc_ops __read_mostly = {
99 .priv_size = sizeof(struct fifo_sched_data),
100 .enqueue = pfifo_enqueue,
101 .dequeue = qdisc_dequeue_head,
102 .peek = qdisc_peek_head,
103 .drop = qdisc_queue_drop,
105 .reset = qdisc_reset_queue,
108 .owner = THIS_MODULE,
110 EXPORT_SYMBOL(pfifo_qdisc_ops);
112 struct Qdisc_ops bfifo_qdisc_ops __read_mostly = {
114 .priv_size = sizeof(struct fifo_sched_data),
115 .enqueue = bfifo_enqueue,
116 .dequeue = qdisc_dequeue_head,
117 .peek = qdisc_peek_head,
118 .drop = qdisc_queue_drop,
120 .reset = qdisc_reset_queue,
123 .owner = THIS_MODULE,
125 EXPORT_SYMBOL(bfifo_qdisc_ops);
127 struct Qdisc_ops pfifo_head_drop_qdisc_ops __read_mostly = {
128 .id = "pfifo_head_drop",
129 .priv_size = sizeof(struct fifo_sched_data),
130 .enqueue = pfifo_tail_enqueue,
131 .dequeue = qdisc_dequeue_head,
132 .peek = qdisc_peek_head,
133 .drop = qdisc_queue_drop_head,
135 .reset = qdisc_reset_queue,
138 .owner = THIS_MODULE,
141 /* Pass size change message down to embedded FIFO */
142 int fifo_set_limit(struct Qdisc *q, unsigned int limit)
147 /* Hack to avoid sending change message to non-FIFO */
148 if (strncmp(q->ops->id + 1, "fifo", 4) != 0)
151 nla = kmalloc(nla_attr_size(sizeof(struct tc_fifo_qopt)), GFP_KERNEL);
153 nla->nla_type = RTM_NEWQDISC;
154 nla->nla_len = nla_attr_size(sizeof(struct tc_fifo_qopt));
155 ((struct tc_fifo_qopt *)nla_data(nla))->limit = limit;
157 ret = q->ops->change(q, nla);
162 EXPORT_SYMBOL(fifo_set_limit);
164 struct Qdisc *fifo_create_dflt(struct Qdisc *sch, struct Qdisc_ops *ops,
170 q = qdisc_create_dflt(sch->dev_queue, ops, TC_H_MAKE(sch->handle, 1));
172 err = fifo_set_limit(q, limit);
179 return q ? : ERR_PTR(err);
181 EXPORT_SYMBOL(fifo_create_dflt);