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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 | ||
22 | static 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 | ||
30 | static 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 | ||
38 | static 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 | qdisc_qstats_drop(sch); | |
46 | qdisc_enqueue_tail(skb, sch); | |
47 | ||
48 | return NET_XMIT_CN; | |
49 | } | |
50 | ||
51 | static 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; | |
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 | ||
84 | static 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 | ||
92 | nla_put_failure: | |
93 | return -1; | |
94 | } | |
95 | ||
96 | struct 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 | }; | |
109 | EXPORT_SYMBOL(pfifo_qdisc_ops); | |
110 | ||
111 | struct 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 | }; | |
124 | EXPORT_SYMBOL(bfifo_qdisc_ops); | |
125 | ||
126 | struct 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 */ | |
141 | int 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 | } | |
161 | EXPORT_SYMBOL(fifo_set_limit); | |
162 | ||
163 | struct 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 | } | |
180 | EXPORT_SYMBOL(fifo_create_dflt); |