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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
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
Linus Torvalds1da177e2005-04-16 15:20:36 -070012#include <linux/module.h>
Tejun Heo5a0e3ad2010-03-24 17:04:11 +090013#include <linux/slab.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070014#include <linux/types.h>
15#include <linux/kernel.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070016#include <linux/errno.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070017#include <linux/skbuff.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070018#include <net/pkt_sched.h>
19
20/* 1 band FIFO pseudo-"scheduler" */
21
Eric Dumazetcc7ec452011-01-19 19:26:56 +000022static int bfifo_enqueue(struct sk_buff *skb, struct Qdisc *sch)
Linus Torvalds1da177e2005-04-16 15:20:36 -070023{
Eric Dumazetd2760552011-03-03 11:10:02 -080024 if (likely(sch->qstats.backlog + qdisc_pkt_len(skb) <= sch->limit))
Thomas Grafaaae3012005-06-18 22:57:42 -070025 return qdisc_enqueue_tail(skb, sch);
Linus Torvalds1da177e2005-04-16 15:20:36 -070026
Thomas Grafaaae3012005-06-18 22:57:42 -070027 return qdisc_reshape_fail(skb, sch);
Linus Torvalds1da177e2005-04-16 15:20:36 -070028}
29
Eric Dumazetcc7ec452011-01-19 19:26:56 +000030static int pfifo_enqueue(struct sk_buff *skb, struct Qdisc *sch)
Linus Torvalds1da177e2005-04-16 15:20:36 -070031{
Eric Dumazetd2760552011-03-03 11:10:02 -080032 if (likely(skb_queue_len(&sch->q) < sch->limit))
Thomas Grafaaae3012005-06-18 22:57:42 -070033 return qdisc_enqueue_tail(skb, sch);
Linus Torvalds1da177e2005-04-16 15:20:36 -070034
Thomas Grafaaae3012005-06-18 22:57:42 -070035 return qdisc_reshape_fail(skb, sch);
Linus Torvalds1da177e2005-04-16 15:20:36 -070036}
37
Eric Dumazetcc7ec452011-01-19 19:26:56 +000038static int pfifo_tail_enqueue(struct sk_buff *skb, struct Qdisc *sch)
Hagen Paul Pfeifer57dbb2d2010-01-24 12:30:59 +000039{
Eric Dumazetd2760552011-03-03 11:10:02 -080040 if (likely(skb_queue_len(&sch->q) < sch->limit))
Hagen Paul Pfeifer57dbb2d2010-01-24 12:30:59 +000041 return qdisc_enqueue_tail(skb, sch);
42
43 /* queue full, remove one skb to fulfill the limit */
Eric Dumazet9190b3b2011-01-20 23:31:33 -080044 __qdisc_queue_drop_head(sch, &sch->q);
John Fastabend25331d62014-09-28 11:53:29 -070045 qdisc_qstats_drop(sch);
Hagen Paul Pfeifer57dbb2d2010-01-24 12:30:59 +000046 qdisc_enqueue_tail(skb, sch);
47
48 return NET_XMIT_CN;
49}
50
Patrick McHardy1e904742008-01-22 22:11:17 -080051static int fifo_init(struct Qdisc *sch, struct nlattr *opt)
Linus Torvalds1da177e2005-04-16 15:20:36 -070052{
Eric Dumazet23624932011-01-21 16:26:09 -080053 bool bypass;
54 bool is_bfifo = sch->ops == &bfifo_qdisc_ops;
Linus Torvalds1da177e2005-04-16 15:20:36 -070055
56 if (opt == NULL) {
David S. Miller5ce2d482008-07-08 17:06:30 -070057 u32 limit = qdisc_dev(sch)->tx_queue_len ? : 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -070058
Eric Dumazet23624932011-01-21 16:26:09 -080059 if (is_bfifo)
Patrick McHardy64739902009-05-06 16:45:07 -070060 limit *= psched_mtu(qdisc_dev(sch));
Thomas Graf6fc8e842005-06-18 22:58:00 -070061
Eric Dumazetd2760552011-03-03 11:10:02 -080062 sch->limit = limit;
Linus Torvalds1da177e2005-04-16 15:20:36 -070063 } else {
Patrick McHardy1e904742008-01-22 22:11:17 -080064 struct tc_fifo_qopt *ctl = nla_data(opt);
Thomas Graf6fc8e842005-06-18 22:58:00 -070065
Patrick McHardy1e904742008-01-22 22:11:17 -080066 if (nla_len(opt) < sizeof(*ctl))
Linus Torvalds1da177e2005-04-16 15:20:36 -070067 return -EINVAL;
Thomas Graf6fc8e842005-06-18 22:58:00 -070068
Eric Dumazetd2760552011-03-03 11:10:02 -080069 sch->limit = ctl->limit;
Linus Torvalds1da177e2005-04-16 15:20:36 -070070 }
Thomas Graf6fc8e842005-06-18 22:58:00 -070071
Eric Dumazet23624932011-01-21 16:26:09 -080072 if (is_bfifo)
Eric Dumazetd2760552011-03-03 11:10:02 -080073 bypass = sch->limit >= psched_mtu(qdisc_dev(sch));
Eric Dumazet23624932011-01-21 16:26:09 -080074 else
Eric Dumazetd2760552011-03-03 11:10:02 -080075 bypass = sch->limit >= 1;
Eric Dumazet23624932011-01-21 16:26:09 -080076
77 if (bypass)
78 sch->flags |= TCQ_F_CAN_BYPASS;
79 else
80 sch->flags &= ~TCQ_F_CAN_BYPASS;
Linus Torvalds1da177e2005-04-16 15:20:36 -070081 return 0;
82}
83
84static int fifo_dump(struct Qdisc *sch, struct sk_buff *skb)
85{
Eric Dumazetd2760552011-03-03 11:10:02 -080086 struct tc_fifo_qopt opt = { .limit = sch->limit };
Linus Torvalds1da177e2005-04-16 15:20:36 -070087
David S. Miller1b34ec42012-03-29 05:11:39 -040088 if (nla_put(skb, TCA_OPTIONS, sizeof(opt), &opt))
89 goto nla_put_failure;
Linus Torvalds1da177e2005-04-16 15:20:36 -070090 return skb->len;
91
Patrick McHardy1e904742008-01-22 22:11:17 -080092nla_put_failure:
Linus Torvalds1da177e2005-04-16 15:20:36 -070093 return -1;
94}
95
Eric Dumazet20fea082007-11-14 01:44:41 -080096struct Qdisc_ops pfifo_qdisc_ops __read_mostly = {
Linus Torvalds1da177e2005-04-16 15:20:36 -070097 .id = "pfifo",
Eric Dumazetd2760552011-03-03 11:10:02 -080098 .priv_size = 0,
Linus Torvalds1da177e2005-04-16 15:20:36 -070099 .enqueue = pfifo_enqueue,
Thomas Grafaaae3012005-06-18 22:57:42 -0700100 .dequeue = qdisc_dequeue_head,
Patrick McHardy48a8f512008-10-31 00:44:18 -0700101 .peek = qdisc_peek_head,
Thomas Grafaaae3012005-06-18 22:57:42 -0700102 .drop = qdisc_queue_drop,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700103 .init = fifo_init,
Thomas Grafaaae3012005-06-18 22:57:42 -0700104 .reset = qdisc_reset_queue,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700105 .change = fifo_init,
106 .dump = fifo_dump,
107 .owner = THIS_MODULE,
108};
Patrick McHardy62e3ba12008-01-22 22:10:23 -0800109EXPORT_SYMBOL(pfifo_qdisc_ops);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700110
Eric Dumazet20fea082007-11-14 01:44:41 -0800111struct Qdisc_ops bfifo_qdisc_ops __read_mostly = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700112 .id = "bfifo",
Eric Dumazetd2760552011-03-03 11:10:02 -0800113 .priv_size = 0,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700114 .enqueue = bfifo_enqueue,
Thomas Grafaaae3012005-06-18 22:57:42 -0700115 .dequeue = qdisc_dequeue_head,
Patrick McHardy48a8f512008-10-31 00:44:18 -0700116 .peek = qdisc_peek_head,
Thomas Grafaaae3012005-06-18 22:57:42 -0700117 .drop = qdisc_queue_drop,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700118 .init = fifo_init,
Thomas Grafaaae3012005-06-18 22:57:42 -0700119 .reset = qdisc_reset_queue,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700120 .change = fifo_init,
121 .dump = fifo_dump,
122 .owner = THIS_MODULE,
123};
Linus Torvalds1da177e2005-04-16 15:20:36 -0700124EXPORT_SYMBOL(bfifo_qdisc_ops);
Patrick McHardyfb0305c2008-07-05 23:40:21 -0700125
Hagen Paul Pfeifer57dbb2d2010-01-24 12:30:59 +0000126struct Qdisc_ops pfifo_head_drop_qdisc_ops __read_mostly = {
127 .id = "pfifo_head_drop",
Eric Dumazetd2760552011-03-03 11:10:02 -0800128 .priv_size = 0,
Hagen Paul Pfeifer57dbb2d2010-01-24 12:30:59 +0000129 .enqueue = pfifo_tail_enqueue,
130 .dequeue = qdisc_dequeue_head,
131 .peek = qdisc_peek_head,
132 .drop = qdisc_queue_drop_head,
133 .init = fifo_init,
134 .reset = qdisc_reset_queue,
135 .change = fifo_init,
136 .dump = fifo_dump,
137 .owner = THIS_MODULE,
138};
139
Patrick McHardyfb0305c2008-07-05 23:40:21 -0700140/* Pass size change message down to embedded FIFO */
141int fifo_set_limit(struct Qdisc *q, unsigned int limit)
142{
143 struct nlattr *nla;
144 int ret = -ENOMEM;
145
146 /* Hack to avoid sending change message to non-FIFO */
147 if (strncmp(q->ops->id + 1, "fifo", 4) != 0)
148 return 0;
149
150 nla = kmalloc(nla_attr_size(sizeof(struct tc_fifo_qopt)), GFP_KERNEL);
151 if (nla) {
152 nla->nla_type = RTM_NEWQDISC;
153 nla->nla_len = nla_attr_size(sizeof(struct tc_fifo_qopt));
154 ((struct tc_fifo_qopt *)nla_data(nla))->limit = limit;
155
156 ret = q->ops->change(q, nla);
157 kfree(nla);
158 }
159 return ret;
160}
161EXPORT_SYMBOL(fifo_set_limit);
162
163struct Qdisc *fifo_create_dflt(struct Qdisc *sch, struct Qdisc_ops *ops,
164 unsigned int limit)
165{
166 struct Qdisc *q;
167 int err = -ENOMEM;
168
Changli Gao3511c912010-10-16 13:04:08 +0000169 q = qdisc_create_dflt(sch->dev_queue, ops, TC_H_MAKE(sch->handle, 1));
Patrick McHardyfb0305c2008-07-05 23:40:21 -0700170 if (q) {
171 err = fifo_set_limit(q, limit);
172 if (err < 0) {
173 qdisc_destroy(q);
174 q = NULL;
175 }
176 }
177
178 return q ? : ERR_PTR(err);
179}
180EXPORT_SYMBOL(fifo_create_dflt);