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 sk_buff *skb_head;
50 struct fifo_sched_data *q = qdisc_priv(sch);
52 if (likely(skb_queue_len(&sch->q) < q->limit))
53 return qdisc_enqueue_tail(skb, sch);
55 /* queue full, remove one skb to fulfill the limit */
56 skb_head = qdisc_dequeue_head(sch);
57 sch->bstats.bytes -= qdisc_pkt_len(skb_head);
58 sch->bstats.packets--;
62 qdisc_enqueue_tail(skb, sch);
67 static int fifo_init(struct Qdisc *sch, struct nlattr *opt)
69 struct fifo_sched_data *q = qdisc_priv(sch);
72 u32 limit = qdisc_dev(sch)->tx_queue_len ? : 1;
74 if (sch->ops == &bfifo_qdisc_ops)
75 limit *= psched_mtu(qdisc_dev(sch));
79 struct tc_fifo_qopt *ctl = nla_data(opt);
81 if (nla_len(opt) < sizeof(*ctl))
84 q->limit = ctl->limit;
90 static int fifo_dump(struct Qdisc *sch, struct sk_buff *skb)
92 struct fifo_sched_data *q = qdisc_priv(sch);
93 struct tc_fifo_qopt opt = { .limit = q->limit };
95 NLA_PUT(skb, TCA_OPTIONS, sizeof(opt), &opt);
102 struct Qdisc_ops pfifo_qdisc_ops __read_mostly = {
104 .priv_size = sizeof(struct fifo_sched_data),
105 .enqueue = pfifo_enqueue,
106 .dequeue = qdisc_dequeue_head,
107 .peek = qdisc_peek_head,
108 .drop = qdisc_queue_drop,
110 .reset = qdisc_reset_queue,
113 .owner = THIS_MODULE,
115 EXPORT_SYMBOL(pfifo_qdisc_ops);
117 struct Qdisc_ops bfifo_qdisc_ops __read_mostly = {
119 .priv_size = sizeof(struct fifo_sched_data),
120 .enqueue = bfifo_enqueue,
121 .dequeue = qdisc_dequeue_head,
122 .peek = qdisc_peek_head,
123 .drop = qdisc_queue_drop,
125 .reset = qdisc_reset_queue,
128 .owner = THIS_MODULE,
130 EXPORT_SYMBOL(bfifo_qdisc_ops);
132 struct Qdisc_ops pfifo_head_drop_qdisc_ops __read_mostly = {
133 .id = "pfifo_head_drop",
134 .priv_size = sizeof(struct fifo_sched_data),
135 .enqueue = pfifo_tail_enqueue,
136 .dequeue = qdisc_dequeue_head,
137 .peek = qdisc_peek_head,
138 .drop = qdisc_queue_drop_head,
140 .reset = qdisc_reset_queue,
143 .owner = THIS_MODULE,
146 /* Pass size change message down to embedded FIFO */
147 int fifo_set_limit(struct Qdisc *q, unsigned int limit)
152 /* Hack to avoid sending change message to non-FIFO */
153 if (strncmp(q->ops->id + 1, "fifo", 4) != 0)
156 nla = kmalloc(nla_attr_size(sizeof(struct tc_fifo_qopt)), GFP_KERNEL);
158 nla->nla_type = RTM_NEWQDISC;
159 nla->nla_len = nla_attr_size(sizeof(struct tc_fifo_qopt));
160 ((struct tc_fifo_qopt *)nla_data(nla))->limit = limit;
162 ret = q->ops->change(q, nla);
167 EXPORT_SYMBOL(fifo_set_limit);
169 struct Qdisc *fifo_create_dflt(struct Qdisc *sch, struct Qdisc_ops *ops,
175 q = qdisc_create_dflt(sch->dev_queue, ops, TC_H_MAKE(sch->handle, 1));
177 err = fifo_set_limit(q, limit);
184 return q ? : ERR_PTR(err);
186 EXPORT_SYMBOL(fifo_create_dflt);