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1 | /* | |
2 | * net/sched/sch_red.c Random Early Detection 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 | * Changes: | |
12 | * J Hadi Salim 980914: computation fixes | |
13 | * Alexey Makarenko <makar@phoenix.kharkov.ua> 990814: qave on idle link was calculated incorrectly. | |
14 | * J Hadi Salim 980816: ECN support | |
15 | */ | |
16 | ||
17 | #include <linux/module.h> | |
18 | #include <linux/types.h> | |
19 | #include <linux/kernel.h> | |
20 | #include <linux/skbuff.h> | |
21 | #include <net/pkt_sched.h> | |
22 | #include <net/inet_ecn.h> | |
23 | #include <net/red.h> | |
24 | ||
25 | ||
26 | /* Parameters, settable by user: | |
27 | ----------------------------- | |
28 | ||
29 | limit - bytes (must be > qth_max + burst) | |
30 | ||
31 | Hard limit on queue length, should be chosen >qth_max | |
32 | to allow packet bursts. This parameter does not | |
33 | affect the algorithms behaviour and can be chosen | |
34 | arbitrarily high (well, less than ram size) | |
35 | Really, this limit will never be reached | |
36 | if RED works correctly. | |
37 | */ | |
38 | ||
39 | struct red_sched_data | |
40 | { | |
41 | u32 limit; /* HARD maximal queue length */ | |
42 | unsigned char flags; | |
43 | struct red_parms parms; | |
44 | struct red_stats stats; | |
45 | struct Qdisc *qdisc; | |
46 | }; | |
47 | ||
48 | static inline int red_use_ecn(struct red_sched_data *q) | |
49 | { | |
50 | return q->flags & TC_RED_ECN; | |
51 | } | |
52 | ||
53 | static inline int red_use_harddrop(struct red_sched_data *q) | |
54 | { | |
55 | return q->flags & TC_RED_HARDDROP; | |
56 | } | |
57 | ||
58 | static int red_enqueue(struct sk_buff *skb, struct Qdisc* sch) | |
59 | { | |
60 | struct red_sched_data *q = qdisc_priv(sch); | |
61 | struct Qdisc *child = q->qdisc; | |
62 | int ret; | |
63 | ||
64 | q->parms.qavg = red_calc_qavg(&q->parms, child->qstats.backlog); | |
65 | ||
66 | if (red_is_idling(&q->parms)) | |
67 | red_end_of_idle_period(&q->parms); | |
68 | ||
69 | switch (red_action(&q->parms, q->parms.qavg)) { | |
70 | case RED_DONT_MARK: | |
71 | break; | |
72 | ||
73 | case RED_PROB_MARK: | |
74 | sch->qstats.overlimits++; | |
75 | if (!red_use_ecn(q) || !INET_ECN_set_ce(skb)) { | |
76 | q->stats.prob_drop++; | |
77 | goto congestion_drop; | |
78 | } | |
79 | ||
80 | q->stats.prob_mark++; | |
81 | break; | |
82 | ||
83 | case RED_HARD_MARK: | |
84 | sch->qstats.overlimits++; | |
85 | if (red_use_harddrop(q) || !red_use_ecn(q) || | |
86 | !INET_ECN_set_ce(skb)) { | |
87 | q->stats.forced_drop++; | |
88 | goto congestion_drop; | |
89 | } | |
90 | ||
91 | q->stats.forced_mark++; | |
92 | break; | |
93 | } | |
94 | ||
95 | ret = child->enqueue(skb, child); | |
96 | if (likely(ret == NET_XMIT_SUCCESS)) { | |
97 | sch->bstats.bytes += skb->len; | |
98 | sch->bstats.packets++; | |
99 | sch->q.qlen++; | |
100 | } else { | |
101 | q->stats.pdrop++; | |
102 | sch->qstats.drops++; | |
103 | } | |
104 | return ret; | |
105 | ||
106 | congestion_drop: | |
107 | qdisc_drop(skb, sch); | |
108 | return NET_XMIT_CN; | |
109 | } | |
110 | ||
111 | static int red_requeue(struct sk_buff *skb, struct Qdisc* sch) | |
112 | { | |
113 | struct red_sched_data *q = qdisc_priv(sch); | |
114 | struct Qdisc *child = q->qdisc; | |
115 | int ret; | |
116 | ||
117 | if (red_is_idling(&q->parms)) | |
118 | red_end_of_idle_period(&q->parms); | |
119 | ||
120 | ret = child->ops->requeue(skb, child); | |
121 | if (likely(ret == NET_XMIT_SUCCESS)) { | |
122 | sch->qstats.requeues++; | |
123 | sch->q.qlen++; | |
124 | } | |
125 | return ret; | |
126 | } | |
127 | ||
128 | static struct sk_buff * red_dequeue(struct Qdisc* sch) | |
129 | { | |
130 | struct sk_buff *skb; | |
131 | struct red_sched_data *q = qdisc_priv(sch); | |
132 | struct Qdisc *child = q->qdisc; | |
133 | ||
134 | skb = child->dequeue(child); | |
135 | if (skb) | |
136 | sch->q.qlen--; | |
137 | else if (!red_is_idling(&q->parms)) | |
138 | red_start_of_idle_period(&q->parms); | |
139 | ||
140 | return skb; | |
141 | } | |
142 | ||
143 | static unsigned int red_drop(struct Qdisc* sch) | |
144 | { | |
145 | struct red_sched_data *q = qdisc_priv(sch); | |
146 | struct Qdisc *child = q->qdisc; | |
147 | unsigned int len; | |
148 | ||
149 | if (child->ops->drop && (len = child->ops->drop(child)) > 0) { | |
150 | q->stats.other++; | |
151 | sch->qstats.drops++; | |
152 | sch->q.qlen--; | |
153 | return len; | |
154 | } | |
155 | ||
156 | if (!red_is_idling(&q->parms)) | |
157 | red_start_of_idle_period(&q->parms); | |
158 | ||
159 | return 0; | |
160 | } | |
161 | ||
162 | static void red_reset(struct Qdisc* sch) | |
163 | { | |
164 | struct red_sched_data *q = qdisc_priv(sch); | |
165 | ||
166 | qdisc_reset(q->qdisc); | |
167 | sch->q.qlen = 0; | |
168 | red_restart(&q->parms); | |
169 | } | |
170 | ||
171 | static void red_destroy(struct Qdisc *sch) | |
172 | { | |
173 | struct red_sched_data *q = qdisc_priv(sch); | |
174 | qdisc_destroy(q->qdisc); | |
175 | } | |
176 | ||
177 | static const struct nla_policy red_policy[TCA_RED_MAX + 1] = { | |
178 | [TCA_RED_PARMS] = { .len = sizeof(struct tc_red_qopt) }, | |
179 | [TCA_RED_STAB] = { .len = RED_STAB_SIZE }, | |
180 | }; | |
181 | ||
182 | static int red_change(struct Qdisc *sch, struct nlattr *opt) | |
183 | { | |
184 | struct red_sched_data *q = qdisc_priv(sch); | |
185 | struct nlattr *tb[TCA_RED_MAX + 1]; | |
186 | struct tc_red_qopt *ctl; | |
187 | struct Qdisc *child = NULL; | |
188 | int err; | |
189 | ||
190 | if (opt == NULL) | |
191 | return -EINVAL; | |
192 | ||
193 | err = nla_parse_nested(tb, TCA_RED_MAX, opt, red_policy); | |
194 | if (err < 0) | |
195 | return err; | |
196 | ||
197 | if (tb[TCA_RED_PARMS] == NULL || | |
198 | tb[TCA_RED_STAB] == NULL) | |
199 | return -EINVAL; | |
200 | ||
201 | ctl = nla_data(tb[TCA_RED_PARMS]); | |
202 | ||
203 | if (ctl->limit > 0) { | |
204 | child = fifo_create_dflt(sch, &bfifo_qdisc_ops, ctl->limit); | |
205 | if (IS_ERR(child)) | |
206 | return PTR_ERR(child); | |
207 | } | |
208 | ||
209 | sch_tree_lock(sch); | |
210 | q->flags = ctl->flags; | |
211 | q->limit = ctl->limit; | |
212 | if (child) { | |
213 | qdisc_tree_decrease_qlen(q->qdisc, q->qdisc->q.qlen); | |
214 | qdisc_destroy(xchg(&q->qdisc, child)); | |
215 | } | |
216 | ||
217 | red_set_parms(&q->parms, ctl->qth_min, ctl->qth_max, ctl->Wlog, | |
218 | ctl->Plog, ctl->Scell_log, | |
219 | nla_data(tb[TCA_RED_STAB])); | |
220 | ||
221 | if (skb_queue_empty(&sch->q)) | |
222 | red_end_of_idle_period(&q->parms); | |
223 | ||
224 | sch_tree_unlock(sch); | |
225 | return 0; | |
226 | } | |
227 | ||
228 | static int red_init(struct Qdisc* sch, struct nlattr *opt) | |
229 | { | |
230 | struct red_sched_data *q = qdisc_priv(sch); | |
231 | ||
232 | q->qdisc = &noop_qdisc; | |
233 | return red_change(sch, opt); | |
234 | } | |
235 | ||
236 | static int red_dump(struct Qdisc *sch, struct sk_buff *skb) | |
237 | { | |
238 | struct red_sched_data *q = qdisc_priv(sch); | |
239 | struct nlattr *opts = NULL; | |
240 | struct tc_red_qopt opt = { | |
241 | .limit = q->limit, | |
242 | .flags = q->flags, | |
243 | .qth_min = q->parms.qth_min >> q->parms.Wlog, | |
244 | .qth_max = q->parms.qth_max >> q->parms.Wlog, | |
245 | .Wlog = q->parms.Wlog, | |
246 | .Plog = q->parms.Plog, | |
247 | .Scell_log = q->parms.Scell_log, | |
248 | }; | |
249 | ||
250 | opts = nla_nest_start(skb, TCA_OPTIONS); | |
251 | if (opts == NULL) | |
252 | goto nla_put_failure; | |
253 | NLA_PUT(skb, TCA_RED_PARMS, sizeof(opt), &opt); | |
254 | return nla_nest_end(skb, opts); | |
255 | ||
256 | nla_put_failure: | |
257 | nla_nest_cancel(skb, opts); | |
258 | return -EMSGSIZE; | |
259 | } | |
260 | ||
261 | static int red_dump_stats(struct Qdisc *sch, struct gnet_dump *d) | |
262 | { | |
263 | struct red_sched_data *q = qdisc_priv(sch); | |
264 | struct tc_red_xstats st = { | |
265 | .early = q->stats.prob_drop + q->stats.forced_drop, | |
266 | .pdrop = q->stats.pdrop, | |
267 | .other = q->stats.other, | |
268 | .marked = q->stats.prob_mark + q->stats.forced_mark, | |
269 | }; | |
270 | ||
271 | return gnet_stats_copy_app(d, &st, sizeof(st)); | |
272 | } | |
273 | ||
274 | static int red_dump_class(struct Qdisc *sch, unsigned long cl, | |
275 | struct sk_buff *skb, struct tcmsg *tcm) | |
276 | { | |
277 | struct red_sched_data *q = qdisc_priv(sch); | |
278 | ||
279 | if (cl != 1) | |
280 | return -ENOENT; | |
281 | tcm->tcm_handle |= TC_H_MIN(1); | |
282 | tcm->tcm_info = q->qdisc->handle; | |
283 | return 0; | |
284 | } | |
285 | ||
286 | static int red_graft(struct Qdisc *sch, unsigned long arg, struct Qdisc *new, | |
287 | struct Qdisc **old) | |
288 | { | |
289 | struct red_sched_data *q = qdisc_priv(sch); | |
290 | ||
291 | if (new == NULL) | |
292 | new = &noop_qdisc; | |
293 | ||
294 | sch_tree_lock(sch); | |
295 | *old = xchg(&q->qdisc, new); | |
296 | qdisc_tree_decrease_qlen(*old, (*old)->q.qlen); | |
297 | qdisc_reset(*old); | |
298 | sch_tree_unlock(sch); | |
299 | return 0; | |
300 | } | |
301 | ||
302 | static struct Qdisc *red_leaf(struct Qdisc *sch, unsigned long arg) | |
303 | { | |
304 | struct red_sched_data *q = qdisc_priv(sch); | |
305 | return q->qdisc; | |
306 | } | |
307 | ||
308 | static unsigned long red_get(struct Qdisc *sch, u32 classid) | |
309 | { | |
310 | return 1; | |
311 | } | |
312 | ||
313 | static void red_put(struct Qdisc *sch, unsigned long arg) | |
314 | { | |
315 | return; | |
316 | } | |
317 | ||
318 | static int red_change_class(struct Qdisc *sch, u32 classid, u32 parentid, | |
319 | struct nlattr **tca, unsigned long *arg) | |
320 | { | |
321 | return -ENOSYS; | |
322 | } | |
323 | ||
324 | static int red_delete(struct Qdisc *sch, unsigned long cl) | |
325 | { | |
326 | return -ENOSYS; | |
327 | } | |
328 | ||
329 | static void red_walk(struct Qdisc *sch, struct qdisc_walker *walker) | |
330 | { | |
331 | if (!walker->stop) { | |
332 | if (walker->count >= walker->skip) | |
333 | if (walker->fn(sch, 1, walker) < 0) { | |
334 | walker->stop = 1; | |
335 | return; | |
336 | } | |
337 | walker->count++; | |
338 | } | |
339 | } | |
340 | ||
341 | static struct tcf_proto **red_find_tcf(struct Qdisc *sch, unsigned long cl) | |
342 | { | |
343 | return NULL; | |
344 | } | |
345 | ||
346 | static const struct Qdisc_class_ops red_class_ops = { | |
347 | .graft = red_graft, | |
348 | .leaf = red_leaf, | |
349 | .get = red_get, | |
350 | .put = red_put, | |
351 | .change = red_change_class, | |
352 | .delete = red_delete, | |
353 | .walk = red_walk, | |
354 | .tcf_chain = red_find_tcf, | |
355 | .dump = red_dump_class, | |
356 | }; | |
357 | ||
358 | static struct Qdisc_ops red_qdisc_ops __read_mostly = { | |
359 | .id = "red", | |
360 | .priv_size = sizeof(struct red_sched_data), | |
361 | .cl_ops = &red_class_ops, | |
362 | .enqueue = red_enqueue, | |
363 | .dequeue = red_dequeue, | |
364 | .requeue = red_requeue, | |
365 | .drop = red_drop, | |
366 | .init = red_init, | |
367 | .reset = red_reset, | |
368 | .destroy = red_destroy, | |
369 | .change = red_change, | |
370 | .dump = red_dump, | |
371 | .dump_stats = red_dump_stats, | |
372 | .owner = THIS_MODULE, | |
373 | }; | |
374 | ||
375 | static int __init red_module_init(void) | |
376 | { | |
377 | return register_qdisc(&red_qdisc_ops); | |
378 | } | |
379 | ||
380 | static void __exit red_module_exit(void) | |
381 | { | |
382 | unregister_qdisc(&red_qdisc_ops); | |
383 | } | |
384 | ||
385 | module_init(red_module_init) | |
386 | module_exit(red_module_exit) | |
387 | ||
388 | MODULE_LICENSE("GPL"); |