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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 | struct fifo_sched_data |
23 | { |
24 | u32 limit; |
25 | }; |
26 | |
27 | static int bfifo_enqueue(struct sk_buff *skb, struct Qdisc* sch) |
28 | { |
29 | struct fifo_sched_data *q = qdisc_priv(sch); |
30 | |
31 | if (likely(sch->qstats.backlog + qdisc_pkt_len(skb) <= q->limit)) |
32 | return qdisc_enqueue_tail(skb, sch); |
33 | |
34 | return qdisc_reshape_fail(skb, sch); |
35 | } |
36 | |
37 | static int pfifo_enqueue(struct sk_buff *skb, struct Qdisc* sch) |
38 | { |
39 | struct fifo_sched_data *q = qdisc_priv(sch); |
40 | |
41 | if (likely(skb_queue_len(&sch->q) < q->limit)) |
42 | return qdisc_enqueue_tail(skb, sch); |
43 | |
44 | return qdisc_reshape_fail(skb, sch); |
45 | } |
46 | |
47 | static int pfifo_tail_enqueue(struct sk_buff *skb, struct Qdisc* sch) |
48 | { |
49 | struct sk_buff *skb_head; |
50 | struct fifo_sched_data *q = qdisc_priv(sch); |
51 | |
52 | if (likely(skb_queue_len(&sch->q) < q->limit)) |
53 | return qdisc_enqueue_tail(skb, sch); |
54 | |
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--; |
59 | sch->qstats.drops++; |
60 | kfree_skb(skb_head); |
61 | |
62 | qdisc_enqueue_tail(skb, sch); |
63 | |
64 | return NET_XMIT_CN; |
65 | } |
66 | |
67 | static int fifo_init(struct Qdisc *sch, struct nlattr *opt) |
68 | { |
69 | struct fifo_sched_data *q = qdisc_priv(sch); |
70 | |
71 | if (opt == NULL) { |
72 | u32 limit = qdisc_dev(sch)->tx_queue_len ? : 1; |
73 | |
74 | if (sch->ops == &bfifo_qdisc_ops) |
75 | limit *= psched_mtu(qdisc_dev(sch)); |
76 | |
77 | q->limit = limit; |
78 | } else { |
79 | struct tc_fifo_qopt *ctl = nla_data(opt); |
80 | |
81 | if (nla_len(opt) < sizeof(*ctl)) |
82 | return -EINVAL; |
83 | |
84 | q->limit = ctl->limit; |
85 | } |
86 | |
87 | return 0; |
88 | } |
89 | |
90 | static int fifo_dump(struct Qdisc *sch, struct sk_buff *skb) |
91 | { |
92 | struct fifo_sched_data *q = qdisc_priv(sch); |
93 | struct tc_fifo_qopt opt = { .limit = q->limit }; |
94 | |
95 | NLA_PUT(skb, TCA_OPTIONS, sizeof(opt), &opt); |
96 | return skb->len; |
97 | |
98 | nla_put_failure: |
99 | return -1; |
100 | } |
101 | |
102 | struct Qdisc_ops pfifo_qdisc_ops __read_mostly = { |
103 | .id = "pfifo", |
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, |
109 | .init = fifo_init, |
110 | .reset = qdisc_reset_queue, |
111 | .change = fifo_init, |
112 | .dump = fifo_dump, |
113 | .owner = THIS_MODULE, |
114 | }; |
115 | EXPORT_SYMBOL(pfifo_qdisc_ops); |
116 | |
117 | struct Qdisc_ops bfifo_qdisc_ops __read_mostly = { |
118 | .id = "bfifo", |
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, |
124 | .init = fifo_init, |
125 | .reset = qdisc_reset_queue, |
126 | .change = fifo_init, |
127 | .dump = fifo_dump, |
128 | .owner = THIS_MODULE, |
129 | }; |
130 | EXPORT_SYMBOL(bfifo_qdisc_ops); |
131 | |
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, |
139 | .init = fifo_init, |
140 | .reset = qdisc_reset_queue, |
141 | .change = fifo_init, |
142 | .dump = fifo_dump, |
143 | .owner = THIS_MODULE, |
144 | }; |
145 | |
146 | /* Pass size change message down to embedded FIFO */ |
147 | int fifo_set_limit(struct Qdisc *q, unsigned int limit) |
148 | { |
149 | struct nlattr *nla; |
150 | int ret = -ENOMEM; |
151 | |
152 | /* Hack to avoid sending change message to non-FIFO */ |
153 | if (strncmp(q->ops->id + 1, "fifo", 4) != 0) |
154 | return 0; |
155 | |
156 | nla = kmalloc(nla_attr_size(sizeof(struct tc_fifo_qopt)), GFP_KERNEL); |
157 | if (nla) { |
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; |
161 | |
162 | ret = q->ops->change(q, nla); |
163 | kfree(nla); |
164 | } |
165 | return ret; |
166 | } |
167 | EXPORT_SYMBOL(fifo_set_limit); |
168 | |
169 | struct Qdisc *fifo_create_dflt(struct Qdisc *sch, struct Qdisc_ops *ops, |
170 | unsigned int limit) |
171 | { |
172 | struct Qdisc *q; |
173 | int err = -ENOMEM; |
174 | |
175 | q = qdisc_create_dflt(qdisc_dev(sch), sch->dev_queue, |
176 | ops, TC_H_MAKE(sch->handle, 1)); |
177 | if (q) { |
178 | err = fifo_set_limit(q, limit); |
179 | if (err < 0) { |
180 | qdisc_destroy(q); |
181 | q = NULL; |
182 | } |
183 | } |
184 | |
185 | return q ? : ERR_PTR(err); |
186 | } |
187 | EXPORT_SYMBOL(fifo_create_dflt); |
188 |
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