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mm: introduce vmf_insert_pfn_prot()
[linux/fpc-iii.git] / net / sched / sch_choke.c
blobeafc0d17d1748cf01f33d206cb46dde6ed81116c
1 /*
2 * net/sched/sch_choke.c CHOKE scheduler
3 *
4 * Copyright (c) 2011 Stephen Hemminger <shemminger@vyatta.com>
5 * Copyright (c) 2011 Eric Dumazet <eric.dumazet@gmail.com>
6 *
7 * This program is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU General Public License
9 * version 2 as published by the Free Software Foundation.
10 *
11 */
12
13 #include <linux/module.h>
14 #include <linux/types.h>
15 #include <linux/kernel.h>
16 #include <linux/skbuff.h>
17 #include <linux/vmalloc.h>
18 #include <net/pkt_sched.h>
19 #include <net/pkt_cls.h>
20 #include <net/inet_ecn.h>
21 #include <net/red.h>
22 #include <net/flow_dissector.h>
23
24 /*
25 CHOKe stateless AQM for fair bandwidth allocation
26 =================================================
27
28 CHOKe (CHOose and Keep for responsive flows, CHOose and Kill for
29 unresponsive flows) is a variant of RED that penalizes misbehaving flows but
30 maintains no flow state. The difference from RED is an additional step
31 during the enqueuing process. If average queue size is over the
32 low threshold (qmin), a packet is chosen at random from the queue.
33 If both the new and chosen packet are from the same flow, both
34 are dropped. Unlike RED, CHOKe is not really a "classful" qdisc because it
35 needs to access packets in queue randomly. It has a minimal class
36 interface to allow overriding the builtin flow classifier with
37 filters.
38
39 Source:
40 R. Pan, B. Prabhakar, and K. Psounis, "CHOKe, A Stateless
41 Active Queue Management Scheme for Approximating Fair Bandwidth Allocation",
42 IEEE INFOCOM, 2000.
43
44 A. Tang, J. Wang, S. Low, "Understanding CHOKe: Throughput and Spatial
45 Characteristics", IEEE/ACM Transactions on Networking, 2004
46
47 */
48
49 /* Upper bound on size of sk_buff table (packets) */
50 #define CHOKE_MAX_QUEUE (128*1024 - 1)
51
52 struct choke_sched_data {
53 /* Parameters */
54 u32 limit;
55 unsigned char flags;
56
57 struct red_parms parms;
58
59 /* Variables */
60 struct red_vars vars;
61 struct {
62 u32 prob_drop; /* Early probability drops */
63 u32 prob_mark; /* Early probability marks */
64 u32 forced_drop; /* Forced drops, qavg > max_thresh */
65 u32 forced_mark; /* Forced marks, qavg > max_thresh */
66 u32 pdrop; /* Drops due to queue limits */
67 u32 other; /* Drops due to drop() calls */
68 u32 matched; /* Drops to flow match */
69 } stats;
70
71 unsigned int head;
72 unsigned int tail;
73
74 unsigned int tab_mask; /* size - 1 */
75
76 struct sk_buff **tab;
77 };
78
79 /* number of elements in queue including holes */
80 static unsigned int choke_len(const struct choke_sched_data *q)
81 {
82 return (q->tail - q->head) & q->tab_mask;
83 }
84
85 /* Is ECN parameter configured */
86 static int use_ecn(const struct choke_sched_data *q)
87 {
88 return q->flags & TC_RED_ECN;
89 }
90
91 /* Should packets over max just be dropped (versus marked) */
92 static int use_harddrop(const struct choke_sched_data *q)
93 {
94 return q->flags & TC_RED_HARDDROP;
95 }
96
97 /* Move head pointer forward to skip over holes */
98 static void choke_zap_head_holes(struct choke_sched_data *q)
99 {
100 do {
101 q->head = (q->head + 1) & q->tab_mask;
102 if (q->head == q->tail)
103 break;
104 } while (q->tab[q->head] == NULL);
105 }
106
107 /* Move tail pointer backwards to reuse holes */
108 static void choke_zap_tail_holes(struct choke_sched_data *q)
109 {
110 do {
111 q->tail = (q->tail - 1) & q->tab_mask;
112 if (q->head == q->tail)
113 break;
114 } while (q->tab[q->tail] == NULL);
115 }
116
117 /* Drop packet from queue array by creating a "hole" */
118 static void choke_drop_by_idx(struct Qdisc *sch, unsigned int idx,
119 struct sk_buff **to_free)
120 {
121 struct choke_sched_data *q = qdisc_priv(sch);
122 struct sk_buff *skb = q->tab[idx];
123
124 q->tab[idx] = NULL;
125
126 if (idx == q->head)
127 choke_zap_head_holes(q);
128 if (idx == q->tail)
129 choke_zap_tail_holes(q);
130
131 qdisc_qstats_backlog_dec(sch, skb);
132 qdisc_tree_reduce_backlog(sch, 1, qdisc_pkt_len(skb));
133 qdisc_drop(skb, sch, to_free);
134 --sch->q.qlen;
135 }
136
137 struct choke_skb_cb {
138 u16 classid;
139 u8 keys_valid;
140 struct flow_keys_digest keys;
141 };
142
143 static inline struct choke_skb_cb *choke_skb_cb(const struct sk_buff *skb)
144 {
145 qdisc_cb_private_validate(skb, sizeof(struct choke_skb_cb));
146 return (struct choke_skb_cb *)qdisc_skb_cb(skb)->data;
147 }
148
149 static inline void choke_set_classid(struct sk_buff *skb, u16 classid)
150 {
151 choke_skb_cb(skb)->classid = classid;
152 }
153
154 /*
155 * Compare flow of two packets
156 * Returns true only if source and destination address and port match.
157 * false for special cases
158 */
159 static bool choke_match_flow(struct sk_buff *skb1,
160 struct sk_buff *skb2)
161 {
162 struct flow_keys temp;
163
164 if (skb1->protocol != skb2->protocol)
165 return false;
166
167 if (!choke_skb_cb(skb1)->keys_valid) {
168 choke_skb_cb(skb1)->keys_valid = 1;
169 skb_flow_dissect_flow_keys(skb1, &temp, 0);
170 make_flow_keys_digest(&choke_skb_cb(skb1)->keys, &temp);
171 }
172
173 if (!choke_skb_cb(skb2)->keys_valid) {
174 choke_skb_cb(skb2)->keys_valid = 1;
175 skb_flow_dissect_flow_keys(skb2, &temp, 0);
176 make_flow_keys_digest(&choke_skb_cb(skb2)->keys, &temp);
177 }
178
179 return !memcmp(&choke_skb_cb(skb1)->keys,
180 &choke_skb_cb(skb2)->keys,
181 sizeof(choke_skb_cb(skb1)->keys));
182 }
183
184 /*
185 * Select a packet at random from queue
186 * HACK: since queue can have holes from previous deletion; retry several
187 * times to find a random skb but then just give up and return the head
188 * Will return NULL if queue is empty (q->head == q->tail)
189 */
190 static struct sk_buff *choke_peek_random(const struct choke_sched_data *q,
191 unsigned int *pidx)
192 {
193 struct sk_buff *skb;
194 int retrys = 3;
195
196 do {
197 *pidx = (q->head + prandom_u32_max(choke_len(q))) & q->tab_mask;
198 skb = q->tab[*pidx];
199 if (skb)
200 return skb;
201 } while (--retrys > 0);
202
203 return q->tab[*pidx = q->head];
204 }
205
206 /*
207 * Compare new packet with random packet in queue
208 * returns true if matched and sets *pidx
209 */
210 static bool choke_match_random(const struct choke_sched_data *q,
211 struct sk_buff *nskb,
212 unsigned int *pidx)
213 {
214 struct sk_buff *oskb;
215
216 if (q->head == q->tail)
217 return false;
218
219 oskb = choke_peek_random(q, pidx);
220 return choke_match_flow(oskb, nskb);
221 }
222
223 static int choke_enqueue(struct sk_buff *skb, struct Qdisc *sch,
224 struct sk_buff **to_free)
225 {
226 struct choke_sched_data *q = qdisc_priv(sch);
227 const struct red_parms *p = &q->parms;
228
229 choke_skb_cb(skb)->keys_valid = 0;
230 /* Compute average queue usage (see RED) */
231 q->vars.qavg = red_calc_qavg(p, &q->vars, sch->q.qlen);
232 if (red_is_idling(&q->vars))
233 red_end_of_idle_period(&q->vars);
234
235 /* Is queue small? */
236 if (q->vars.qavg <= p->qth_min)
237 q->vars.qcount = -1;
238 else {
239 unsigned int idx;
240
241 /* Draw a packet at random from queue and compare flow */
242 if (choke_match_random(q, skb, &idx)) {
243 q->stats.matched++;
244 choke_drop_by_idx(sch, idx, to_free);
245 goto congestion_drop;
246 }
247
248 /* Queue is large, always mark/drop */
249 if (q->vars.qavg > p->qth_max) {
250 q->vars.qcount = -1;
251
252 qdisc_qstats_overlimit(sch);
253 if (use_harddrop(q) || !use_ecn(q) ||
254 !INET_ECN_set_ce(skb)) {
255 q->stats.forced_drop++;
256 goto congestion_drop;
257 }
258
259 q->stats.forced_mark++;
260 } else if (++q->vars.qcount) {
261 if (red_mark_probability(p, &q->vars, q->vars.qavg)) {
262 q->vars.qcount = 0;
263 q->vars.qR = red_random(p);
264
265 qdisc_qstats_overlimit(sch);
266 if (!use_ecn(q) || !INET_ECN_set_ce(skb)) {
267 q->stats.prob_drop++;
268 goto congestion_drop;
269 }
270
271 q->stats.prob_mark++;
272 }
273 } else
274 q->vars.qR = red_random(p);
275 }
276
277 /* Admit new packet */
278 if (sch->q.qlen < q->limit) {
279 q->tab[q->tail] = skb;
280 q->tail = (q->tail + 1) & q->tab_mask;
281 ++sch->q.qlen;
282 qdisc_qstats_backlog_inc(sch, skb);
283 return NET_XMIT_SUCCESS;
284 }
285
286 q->stats.pdrop++;
287 return qdisc_drop(skb, sch, to_free);
288
289 congestion_drop:
290 qdisc_drop(skb, sch, to_free);
291 return NET_XMIT_CN;
292 }
293
294 static struct sk_buff *choke_dequeue(struct Qdisc *sch)
295 {
296 struct choke_sched_data *q = qdisc_priv(sch);
297 struct sk_buff *skb;
298
299 if (q->head == q->tail) {
300 if (!red_is_idling(&q->vars))
301 red_start_of_idle_period(&q->vars);
302 return NULL;
303 }
304
305 skb = q->tab[q->head];
306 q->tab[q->head] = NULL;
307 choke_zap_head_holes(q);
308 --sch->q.qlen;
309 qdisc_qstats_backlog_dec(sch, skb);
310 qdisc_bstats_update(sch, skb);
311
312 return skb;
313 }
314
315 static void choke_reset(struct Qdisc *sch)
316 {
317 struct choke_sched_data *q = qdisc_priv(sch);
318
319 while (q->head != q->tail) {
320 struct sk_buff *skb = q->tab[q->head];
321
322 q->head = (q->head + 1) & q->tab_mask;
323 if (!skb)
324 continue;
325 rtnl_qdisc_drop(skb, sch);
326 }
327
328 sch->q.qlen = 0;
329 sch->qstats.backlog = 0;
330 memset(q->tab, 0, (q->tab_mask + 1) * sizeof(struct sk_buff *));
331 q->head = q->tail = 0;
332 red_restart(&q->vars);
333 }
334
335 static const struct nla_policy choke_policy[TCA_CHOKE_MAX + 1] = {
336 [TCA_CHOKE_PARMS] = { .len = sizeof(struct tc_red_qopt) },
337 [TCA_CHOKE_STAB] = { .len = RED_STAB_SIZE },
338 [TCA_CHOKE_MAX_P] = { .type = NLA_U32 },
339 };
340
341
342 static void choke_free(void *addr)
343 {
344 kvfree(addr);
345 }
346
347 static int choke_change(struct Qdisc *sch, struct nlattr *opt,
348 struct netlink_ext_ack *extack)
349 {
350 struct choke_sched_data *q = qdisc_priv(sch);
351 struct nlattr *tb[TCA_CHOKE_MAX + 1];
352 const struct tc_red_qopt *ctl;
353 int err;
354 struct sk_buff **old = NULL;
355 unsigned int mask;
356 u32 max_P;
357
358 if (opt == NULL)
359 return -EINVAL;
360
361 err = nla_parse_nested(tb, TCA_CHOKE_MAX, opt, choke_policy, NULL);
362 if (err < 0)
363 return err;
364
365 if (tb[TCA_CHOKE_PARMS] == NULL ||
366 tb[TCA_CHOKE_STAB] == NULL)
367 return -EINVAL;
368
369 max_P = tb[TCA_CHOKE_MAX_P] ? nla_get_u32(tb[TCA_CHOKE_MAX_P]) : 0;
370
371 ctl = nla_data(tb[TCA_CHOKE_PARMS]);
372
373 if (!red_check_params(ctl->qth_min, ctl->qth_max, ctl->Wlog))
374 return -EINVAL;
375
376 if (ctl->limit > CHOKE_MAX_QUEUE)
377 return -EINVAL;
378
379 mask = roundup_pow_of_two(ctl->limit + 1) - 1;
380 if (mask != q->tab_mask) {
381 struct sk_buff **ntab;
382
383 ntab = kvmalloc_array((mask + 1), sizeof(struct sk_buff *), GFP_KERNEL | __GFP_ZERO);
384 if (!ntab)
385 return -ENOMEM;
386
387 sch_tree_lock(sch);
388 old = q->tab;
389 if (old) {
390 unsigned int oqlen = sch->q.qlen, tail = 0;
391 unsigned dropped = 0;
392
393 while (q->head != q->tail) {
394 struct sk_buff *skb = q->tab[q->head];
395
396 q->head = (q->head + 1) & q->tab_mask;
397 if (!skb)
398 continue;
399 if (tail < mask) {
400 ntab[tail++] = skb;
401 continue;
402 }
403 dropped += qdisc_pkt_len(skb);
404 qdisc_qstats_backlog_dec(sch, skb);
405 --sch->q.qlen;
406 rtnl_qdisc_drop(skb, sch);
407 }
408 qdisc_tree_reduce_backlog(sch, oqlen - sch->q.qlen, dropped);
409 q->head = 0;
410 q->tail = tail;
411 }
412
413 q->tab_mask = mask;
414 q->tab = ntab;
415 } else
416 sch_tree_lock(sch);
417
418 q->flags = ctl->flags;
419 q->limit = ctl->limit;
420
421 red_set_parms(&q->parms, ctl->qth_min, ctl->qth_max, ctl->Wlog,
422 ctl->Plog, ctl->Scell_log,
423 nla_data(tb[TCA_CHOKE_STAB]),
424 max_P);
425 red_set_vars(&q->vars);
426
427 if (q->head == q->tail)
428 red_end_of_idle_period(&q->vars);
429
430 sch_tree_unlock(sch);
431 choke_free(old);
432 return 0;
433 }
434
435 static int choke_init(struct Qdisc *sch, struct nlattr *opt,
436 struct netlink_ext_ack *extack)
437 {
438 return choke_change(sch, opt, extack);
439 }
440
441 static int choke_dump(struct Qdisc *sch, struct sk_buff *skb)
442 {
443 struct choke_sched_data *q = qdisc_priv(sch);
444 struct nlattr *opts = NULL;
445 struct tc_red_qopt opt = {
446 .limit = q->limit,
447 .flags = q->flags,
448 .qth_min = q->parms.qth_min >> q->parms.Wlog,
449 .qth_max = q->parms.qth_max >> q->parms.Wlog,
450 .Wlog = q->parms.Wlog,
451 .Plog = q->parms.Plog,
452 .Scell_log = q->parms.Scell_log,
453 };
454
455 opts = nla_nest_start(skb, TCA_OPTIONS);
456 if (opts == NULL)
457 goto nla_put_failure;
458
459 if (nla_put(skb, TCA_CHOKE_PARMS, sizeof(opt), &opt) ||
460 nla_put_u32(skb, TCA_CHOKE_MAX_P, q->parms.max_P))
461 goto nla_put_failure;
462 return nla_nest_end(skb, opts);
463
464 nla_put_failure:
465 nla_nest_cancel(skb, opts);
466 return -EMSGSIZE;
467 }
468
469 static int choke_dump_stats(struct Qdisc *sch, struct gnet_dump *d)
470 {
471 struct choke_sched_data *q = qdisc_priv(sch);
472 struct tc_choke_xstats st = {
473 .early = q->stats.prob_drop + q->stats.forced_drop,
474 .marked = q->stats.prob_mark + q->stats.forced_mark,
475 .pdrop = q->stats.pdrop,
476 .other = q->stats.other,
477 .matched = q->stats.matched,
478 };
479
480 return gnet_stats_copy_app(d, &st, sizeof(st));
481 }
482
483 static void choke_destroy(struct Qdisc *sch)
484 {
485 struct choke_sched_data *q = qdisc_priv(sch);
486
487 choke_free(q->tab);
488 }
489
490 static struct sk_buff *choke_peek_head(struct Qdisc *sch)
491 {
492 struct choke_sched_data *q = qdisc_priv(sch);
493
494 return (q->head != q->tail) ? q->tab[q->head] : NULL;
495 }
496
497 static struct Qdisc_ops choke_qdisc_ops __read_mostly = {
498 .id = "choke",
499 .priv_size = sizeof(struct choke_sched_data),
500
501 .enqueue = choke_enqueue,
502 .dequeue = choke_dequeue,
503 .peek = choke_peek_head,
504 .init = choke_init,
505 .destroy = choke_destroy,
506 .reset = choke_reset,
507 .change = choke_change,
508 .dump = choke_dump,
509 .dump_stats = choke_dump_stats,
510 .owner = THIS_MODULE,
511 };
512
513 static int __init choke_module_init(void)
514 {
515 return register_qdisc(&choke_qdisc_ops);
516 }
517
518 static void __exit choke_module_exit(void)
519 {
520 unregister_qdisc(&choke_qdisc_ops);
521 }
522
523 module_init(choke_module_init)
524 module_exit(choke_module_exit)
525
526 MODULE_LICENSE("GPL");
Linux with added FPC-III support