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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/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>
19
20/* 1 band FIFO pseudo-"scheduler" */
21
22static int bfifo_enqueue(struct sk_buff *skb, struct Qdisc *sch)
23{
24 if (likely(sch->qstats.backlog + qdisc_pkt_len(skb) <= sch->limit))
25 return qdisc_enqueue_tail(skb, sch);
26
27 return qdisc_reshape_fail(skb, sch);
28}
29
30static int pfifo_enqueue(struct sk_buff *skb, struct Qdisc *sch)
31{
32 if (likely(skb_queue_len(&sch->q) < sch->limit))
33 return qdisc_enqueue_tail(skb, sch);
34
35 return qdisc_reshape_fail(skb, sch);
36}
37
38static int pfifo_tail_enqueue(struct sk_buff *skb, struct Qdisc *sch)
39{
40 if (likely(skb_queue_len(&sch->q) < sch->limit))
41 return qdisc_enqueue_tail(skb, sch);
42
43 /* queue full, remove one skb to fulfill the limit */
44 __qdisc_queue_drop_head(sch, &sch->q);
45 sch->qstats.drops++;
46 qdisc_enqueue_tail(skb, sch);
47
48 return NET_XMIT_CN;
49}
50
51static int fifo_init(struct Qdisc *sch, struct nlattr *opt)
52{
53 bool bypass;
54 bool is_bfifo = sch->ops == &bfifo_qdisc_ops;
55
56 if (opt == NULL) {
57 u32 limit = qdisc_dev(sch)->tx_queue_len ? : 1;
58
59 if (is_bfifo)
60 limit *= psched_mtu(qdisc_dev(sch));
61
62 sch->limit = limit;
63 } else {
64 struct tc_fifo_qopt *ctl = nla_data(opt);
65
66 if (nla_len(opt) < sizeof(*ctl))
67 return -EINVAL;
68
69 sch->limit = ctl->limit;
70 }
71
72 if (is_bfifo)
73 bypass = sch->limit >= psched_mtu(qdisc_dev(sch));
74 else
75 bypass = sch->limit >= 1;
76
77 if (bypass)
78 sch->flags |= TCQ_F_CAN_BYPASS;
79 else
80 sch->flags &= ~TCQ_F_CAN_BYPASS;
81 return 0;
82}
83
84static int fifo_dump(struct Qdisc *sch, struct sk_buff *skb)
85{
86 struct tc_fifo_qopt opt = { .limit = sch->limit };
87
88 if (nla_put(skb, TCA_OPTIONS, sizeof(opt), &opt))
89 goto nla_put_failure;
90 return skb->len;
91
92nla_put_failure:
93 return -1;
94}
95
96struct Qdisc_ops pfifo_qdisc_ops __read_mostly = {
97 .id = "pfifo",
98 .priv_size = 0,
99 .enqueue = pfifo_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};
109EXPORT_SYMBOL(pfifo_qdisc_ops);
110
111struct Qdisc_ops bfifo_qdisc_ops __read_mostly = {
112 .id = "bfifo",
113 .priv_size = 0,
114 .enqueue = bfifo_enqueue,
115 .dequeue = qdisc_dequeue_head,
116 .peek = qdisc_peek_head,
117 .drop = qdisc_queue_drop,
118 .init = fifo_init,
119 .reset = qdisc_reset_queue,
120 .change = fifo_init,
121 .dump = fifo_dump,
122 .owner = THIS_MODULE,
123};
124EXPORT_SYMBOL(bfifo_qdisc_ops);
125
126struct Qdisc_ops pfifo_head_drop_qdisc_ops __read_mostly = {
127 .id = "pfifo_head_drop",
128 .priv_size = 0,
129 .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
140/* 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
169 q = qdisc_create_dflt(sch->dev_queue, ops, TC_H_MAKE(sch->handle, 1));
170 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);
1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * net/sched/sch_fifo.c The simplest FIFO queue.
4 *
5 * Authors: Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
6 */
7
8#include <linux/module.h>
9#include <linux/slab.h>
10#include <linux/types.h>
11#include <linux/kernel.h>
12#include <linux/errno.h>
13#include <linux/skbuff.h>
14#include <net/pkt_sched.h>
15
16/* 1 band FIFO pseudo-"scheduler" */
17
18static int bfifo_enqueue(struct sk_buff *skb, struct Qdisc *sch,
19 struct sk_buff **to_free)
20{
21 if (likely(sch->qstats.backlog + qdisc_pkt_len(skb) <= sch->limit))
22 return qdisc_enqueue_tail(skb, sch);
23
24 return qdisc_drop(skb, sch, to_free);
25}
26
27static int pfifo_enqueue(struct sk_buff *skb, struct Qdisc *sch,
28 struct sk_buff **to_free)
29{
30 if (likely(sch->q.qlen < sch->limit))
31 return qdisc_enqueue_tail(skb, sch);
32
33 return qdisc_drop(skb, sch, to_free);
34}
35
36static int pfifo_tail_enqueue(struct sk_buff *skb, struct Qdisc *sch,
37 struct sk_buff **to_free)
38{
39 unsigned int prev_backlog;
40
41 if (likely(sch->q.qlen < sch->limit))
42 return qdisc_enqueue_tail(skb, sch);
43
44 prev_backlog = sch->qstats.backlog;
45 /* queue full, remove one skb to fulfill the limit */
46 __qdisc_queue_drop_head(sch, &sch->q, to_free);
47 qdisc_qstats_drop(sch);
48 qdisc_enqueue_tail(skb, sch);
49
50 qdisc_tree_reduce_backlog(sch, 0, prev_backlog - sch->qstats.backlog);
51 return NET_XMIT_CN;
52}
53
54static int fifo_init(struct Qdisc *sch, struct nlattr *opt,
55 struct netlink_ext_ack *extack)
56{
57 bool bypass;
58 bool is_bfifo = sch->ops == &bfifo_qdisc_ops;
59
60 if (opt == NULL) {
61 u32 limit = qdisc_dev(sch)->tx_queue_len;
62
63 if (is_bfifo)
64 limit *= psched_mtu(qdisc_dev(sch));
65
66 sch->limit = limit;
67 } else {
68 struct tc_fifo_qopt *ctl = nla_data(opt);
69
70 if (nla_len(opt) < sizeof(*ctl))
71 return -EINVAL;
72
73 sch->limit = ctl->limit;
74 }
75
76 if (is_bfifo)
77 bypass = sch->limit >= psched_mtu(qdisc_dev(sch));
78 else
79 bypass = sch->limit >= 1;
80
81 if (bypass)
82 sch->flags |= TCQ_F_CAN_BYPASS;
83 else
84 sch->flags &= ~TCQ_F_CAN_BYPASS;
85 return 0;
86}
87
88static int fifo_dump(struct Qdisc *sch, struct sk_buff *skb)
89{
90 struct tc_fifo_qopt opt = { .limit = sch->limit };
91
92 if (nla_put(skb, TCA_OPTIONS, sizeof(opt), &opt))
93 goto nla_put_failure;
94 return skb->len;
95
96nla_put_failure:
97 return -1;
98}
99
100struct Qdisc_ops pfifo_qdisc_ops __read_mostly = {
101 .id = "pfifo",
102 .priv_size = 0,
103 .enqueue = pfifo_enqueue,
104 .dequeue = qdisc_dequeue_head,
105 .peek = qdisc_peek_head,
106 .init = fifo_init,
107 .reset = qdisc_reset_queue,
108 .change = fifo_init,
109 .dump = fifo_dump,
110 .owner = THIS_MODULE,
111};
112EXPORT_SYMBOL(pfifo_qdisc_ops);
113
114struct Qdisc_ops bfifo_qdisc_ops __read_mostly = {
115 .id = "bfifo",
116 .priv_size = 0,
117 .enqueue = bfifo_enqueue,
118 .dequeue = qdisc_dequeue_head,
119 .peek = qdisc_peek_head,
120 .init = fifo_init,
121 .reset = qdisc_reset_queue,
122 .change = fifo_init,
123 .dump = fifo_dump,
124 .owner = THIS_MODULE,
125};
126EXPORT_SYMBOL(bfifo_qdisc_ops);
127
128struct Qdisc_ops pfifo_head_drop_qdisc_ops __read_mostly = {
129 .id = "pfifo_head_drop",
130 .priv_size = 0,
131 .enqueue = pfifo_tail_enqueue,
132 .dequeue = qdisc_dequeue_head,
133 .peek = qdisc_peek_head,
134 .init = fifo_init,
135 .reset = qdisc_reset_queue,
136 .change = fifo_init,
137 .dump = fifo_dump,
138 .owner = THIS_MODULE,
139};
140
141/* Pass size change message down to embedded FIFO */
142int fifo_set_limit(struct Qdisc *q, unsigned int limit)
143{
144 struct nlattr *nla;
145 int ret = -ENOMEM;
146
147 /* Hack to avoid sending change message to non-FIFO */
148 if (strncmp(q->ops->id + 1, "fifo", 4) != 0)
149 return 0;
150
151 nla = kmalloc(nla_attr_size(sizeof(struct tc_fifo_qopt)), GFP_KERNEL);
152 if (nla) {
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;
156
157 ret = q->ops->change(q, nla, NULL);
158 kfree(nla);
159 }
160 return ret;
161}
162EXPORT_SYMBOL(fifo_set_limit);
163
164struct Qdisc *fifo_create_dflt(struct Qdisc *sch, struct Qdisc_ops *ops,
165 unsigned int limit,
166 struct netlink_ext_ack *extack)
167{
168 struct Qdisc *q;
169 int err = -ENOMEM;
170
171 q = qdisc_create_dflt(sch->dev_queue, ops, TC_H_MAKE(sch->handle, 1),
172 extack);
173 if (q) {
174 err = fifo_set_limit(q, limit);
175 if (err < 0) {
176 qdisc_put(q);
177 q = NULL;
178 }
179 }
180
181 return q ? : ERR_PTR(err);
182}
183EXPORT_SYMBOL(fifo_create_dflt);