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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/inet_ecn.h>
20#include <net/red.h>
21#include <net/flow_dissector.h>
22
23/*
24 CHOKe stateless AQM for fair bandwidth allocation
25 =================================================
26
27 CHOKe (CHOose and Keep for responsive flows, CHOose and Kill for
28 unresponsive flows) is a variant of RED that penalizes misbehaving flows but
29 maintains no flow state. The difference from RED is an additional step
30 during the enqueuing process. If average queue size is over the
31 low threshold (qmin), a packet is chosen at random from the queue.
32 If both the new and chosen packet are from the same flow, both
33 are dropped. Unlike RED, CHOKe is not really a "classful" qdisc because it
34 needs to access packets in queue randomly. It has a minimal class
35 interface to allow overriding the builtin flow classifier with
36 filters.
37
38 Source:
39 R. Pan, B. Prabhakar, and K. Psounis, "CHOKe, A Stateless
40 Active Queue Management Scheme for Approximating Fair Bandwidth Allocation",
41 IEEE INFOCOM, 2000.
42
43 A. Tang, J. Wang, S. Low, "Understanding CHOKe: Throughput and Spatial
44 Characteristics", IEEE/ACM Transactions on Networking, 2004
45
46 */
47
48/* Upper bound on size of sk_buff table (packets) */
49#define CHOKE_MAX_QUEUE (128*1024 - 1)
50
51struct choke_sched_data {
52/* Parameters */
53 u32 limit;
54 unsigned char flags;
55
56 struct red_parms parms;
57
58/* Variables */
59 struct red_vars vars;
60 struct tcf_proto __rcu *filter_list;
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 */
80static 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 */
86static 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) */
92static 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 */
98static 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 */
108static 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" */
118static void choke_drop_by_idx(struct Qdisc *sch, unsigned int idx)
119{
120 struct choke_sched_data *q = qdisc_priv(sch);
121 struct sk_buff *skb = q->tab[idx];
122
123 q->tab[idx] = NULL;
124
125 if (idx == q->head)
126 choke_zap_head_holes(q);
127 if (idx == q->tail)
128 choke_zap_tail_holes(q);
129
130 qdisc_qstats_backlog_dec(sch, skb);
131 qdisc_tree_reduce_backlog(sch, 1, qdisc_pkt_len(skb));
132 qdisc_drop(skb, sch);
133 --sch->q.qlen;
134}
135
136struct choke_skb_cb {
137 u16 classid;
138 u8 keys_valid;
139 struct flow_keys_digest keys;
140};
141
142static inline struct choke_skb_cb *choke_skb_cb(const struct sk_buff *skb)
143{
144 qdisc_cb_private_validate(skb, sizeof(struct choke_skb_cb));
145 return (struct choke_skb_cb *)qdisc_skb_cb(skb)->data;
146}
147
148static inline void choke_set_classid(struct sk_buff *skb, u16 classid)
149{
150 choke_skb_cb(skb)->classid = classid;
151}
152
153static u16 choke_get_classid(const struct sk_buff *skb)
154{
155 return choke_skb_cb(skb)->classid;
156}
157
158/*
159 * Compare flow of two packets
160 * Returns true only if source and destination address and port match.
161 * false for special cases
162 */
163static bool choke_match_flow(struct sk_buff *skb1,
164 struct sk_buff *skb2)
165{
166 struct flow_keys temp;
167
168 if (skb1->protocol != skb2->protocol)
169 return false;
170
171 if (!choke_skb_cb(skb1)->keys_valid) {
172 choke_skb_cb(skb1)->keys_valid = 1;
173 skb_flow_dissect_flow_keys(skb1, &temp, 0);
174 make_flow_keys_digest(&choke_skb_cb(skb1)->keys, &temp);
175 }
176
177 if (!choke_skb_cb(skb2)->keys_valid) {
178 choke_skb_cb(skb2)->keys_valid = 1;
179 skb_flow_dissect_flow_keys(skb2, &temp, 0);
180 make_flow_keys_digest(&choke_skb_cb(skb2)->keys, &temp);
181 }
182
183 return !memcmp(&choke_skb_cb(skb1)->keys,
184 &choke_skb_cb(skb2)->keys,
185 sizeof(choke_skb_cb(skb1)->keys));
186}
187
188/*
189 * Classify flow using either:
190 * 1. pre-existing classification result in skb
191 * 2. fast internal classification
192 * 3. use TC filter based classification
193 */
194static bool choke_classify(struct sk_buff *skb,
195 struct Qdisc *sch, int *qerr)
196
197{
198 struct choke_sched_data *q = qdisc_priv(sch);
199 struct tcf_result res;
200 struct tcf_proto *fl;
201 int result;
202
203 fl = rcu_dereference_bh(q->filter_list);
204 result = tc_classify(skb, fl, &res, false);
205 if (result >= 0) {
206#ifdef CONFIG_NET_CLS_ACT
207 switch (result) {
208 case TC_ACT_STOLEN:
209 case TC_ACT_QUEUED:
210 *qerr = NET_XMIT_SUCCESS | __NET_XMIT_STOLEN;
211 case TC_ACT_SHOT:
212 return false;
213 }
214#endif
215 choke_set_classid(skb, TC_H_MIN(res.classid));
216 return true;
217 }
218
219 return false;
220}
221
222/*
223 * Select a packet at random from queue
224 * HACK: since queue can have holes from previous deletion; retry several
225 * times to find a random skb but then just give up and return the head
226 * Will return NULL if queue is empty (q->head == q->tail)
227 */
228static struct sk_buff *choke_peek_random(const struct choke_sched_data *q,
229 unsigned int *pidx)
230{
231 struct sk_buff *skb;
232 int retrys = 3;
233
234 do {
235 *pidx = (q->head + prandom_u32_max(choke_len(q))) & q->tab_mask;
236 skb = q->tab[*pidx];
237 if (skb)
238 return skb;
239 } while (--retrys > 0);
240
241 return q->tab[*pidx = q->head];
242}
243
244/*
245 * Compare new packet with random packet in queue
246 * returns true if matched and sets *pidx
247 */
248static bool choke_match_random(const struct choke_sched_data *q,
249 struct sk_buff *nskb,
250 unsigned int *pidx)
251{
252 struct sk_buff *oskb;
253
254 if (q->head == q->tail)
255 return false;
256
257 oskb = choke_peek_random(q, pidx);
258 if (rcu_access_pointer(q->filter_list))
259 return choke_get_classid(nskb) == choke_get_classid(oskb);
260
261 return choke_match_flow(oskb, nskb);
262}
263
264static int choke_enqueue(struct sk_buff *skb, struct Qdisc *sch)
265{
266 int ret = NET_XMIT_SUCCESS | __NET_XMIT_BYPASS;
267 struct choke_sched_data *q = qdisc_priv(sch);
268 const struct red_parms *p = &q->parms;
269
270 if (rcu_access_pointer(q->filter_list)) {
271 /* If using external classifiers, get result and record it. */
272 if (!choke_classify(skb, sch, &ret))
273 goto other_drop; /* Packet was eaten by filter */
274 }
275
276 choke_skb_cb(skb)->keys_valid = 0;
277 /* Compute average queue usage (see RED) */
278 q->vars.qavg = red_calc_qavg(p, &q->vars, sch->q.qlen);
279 if (red_is_idling(&q->vars))
280 red_end_of_idle_period(&q->vars);
281
282 /* Is queue small? */
283 if (q->vars.qavg <= p->qth_min)
284 q->vars.qcount = -1;
285 else {
286 unsigned int idx;
287
288 /* Draw a packet at random from queue and compare flow */
289 if (choke_match_random(q, skb, &idx)) {
290 q->stats.matched++;
291 choke_drop_by_idx(sch, idx);
292 goto congestion_drop;
293 }
294
295 /* Queue is large, always mark/drop */
296 if (q->vars.qavg > p->qth_max) {
297 q->vars.qcount = -1;
298
299 qdisc_qstats_overlimit(sch);
300 if (use_harddrop(q) || !use_ecn(q) ||
301 !INET_ECN_set_ce(skb)) {
302 q->stats.forced_drop++;
303 goto congestion_drop;
304 }
305
306 q->stats.forced_mark++;
307 } else if (++q->vars.qcount) {
308 if (red_mark_probability(p, &q->vars, q->vars.qavg)) {
309 q->vars.qcount = 0;
310 q->vars.qR = red_random(p);
311
312 qdisc_qstats_overlimit(sch);
313 if (!use_ecn(q) || !INET_ECN_set_ce(skb)) {
314 q->stats.prob_drop++;
315 goto congestion_drop;
316 }
317
318 q->stats.prob_mark++;
319 }
320 } else
321 q->vars.qR = red_random(p);
322 }
323
324 /* Admit new packet */
325 if (sch->q.qlen < q->limit) {
326 q->tab[q->tail] = skb;
327 q->tail = (q->tail + 1) & q->tab_mask;
328 ++sch->q.qlen;
329 qdisc_qstats_backlog_inc(sch, skb);
330 return NET_XMIT_SUCCESS;
331 }
332
333 q->stats.pdrop++;
334 return qdisc_drop(skb, sch);
335
336congestion_drop:
337 qdisc_drop(skb, sch);
338 return NET_XMIT_CN;
339
340other_drop:
341 if (ret & __NET_XMIT_BYPASS)
342 qdisc_qstats_drop(sch);
343 kfree_skb(skb);
344 return ret;
345}
346
347static struct sk_buff *choke_dequeue(struct Qdisc *sch)
348{
349 struct choke_sched_data *q = qdisc_priv(sch);
350 struct sk_buff *skb;
351
352 if (q->head == q->tail) {
353 if (!red_is_idling(&q->vars))
354 red_start_of_idle_period(&q->vars);
355 return NULL;
356 }
357
358 skb = q->tab[q->head];
359 q->tab[q->head] = NULL;
360 choke_zap_head_holes(q);
361 --sch->q.qlen;
362 qdisc_qstats_backlog_dec(sch, skb);
363 qdisc_bstats_update(sch, skb);
364
365 return skb;
366}
367
368static unsigned int choke_drop(struct Qdisc *sch)
369{
370 struct choke_sched_data *q = qdisc_priv(sch);
371 unsigned int len;
372
373 len = qdisc_queue_drop(sch);
374 if (len > 0)
375 q->stats.other++;
376 else {
377 if (!red_is_idling(&q->vars))
378 red_start_of_idle_period(&q->vars);
379 }
380
381 return len;
382}
383
384static void choke_reset(struct Qdisc *sch)
385{
386 struct choke_sched_data *q = qdisc_priv(sch);
387
388 while (q->head != q->tail) {
389 struct sk_buff *skb = q->tab[q->head];
390
391 q->head = (q->head + 1) & q->tab_mask;
392 if (!skb)
393 continue;
394 qdisc_qstats_backlog_dec(sch, skb);
395 --sch->q.qlen;
396 qdisc_drop(skb, sch);
397 }
398
399 memset(q->tab, 0, (q->tab_mask + 1) * sizeof(struct sk_buff *));
400 q->head = q->tail = 0;
401 red_restart(&q->vars);
402}
403
404static const struct nla_policy choke_policy[TCA_CHOKE_MAX + 1] = {
405 [TCA_CHOKE_PARMS] = { .len = sizeof(struct tc_red_qopt) },
406 [TCA_CHOKE_STAB] = { .len = RED_STAB_SIZE },
407 [TCA_CHOKE_MAX_P] = { .type = NLA_U32 },
408};
409
410
411static void choke_free(void *addr)
412{
413 kvfree(addr);
414}
415
416static int choke_change(struct Qdisc *sch, struct nlattr *opt)
417{
418 struct choke_sched_data *q = qdisc_priv(sch);
419 struct nlattr *tb[TCA_CHOKE_MAX + 1];
420 const struct tc_red_qopt *ctl;
421 int err;
422 struct sk_buff **old = NULL;
423 unsigned int mask;
424 u32 max_P;
425
426 if (opt == NULL)
427 return -EINVAL;
428
429 err = nla_parse_nested(tb, TCA_CHOKE_MAX, opt, choke_policy);
430 if (err < 0)
431 return err;
432
433 if (tb[TCA_CHOKE_PARMS] == NULL ||
434 tb[TCA_CHOKE_STAB] == NULL)
435 return -EINVAL;
436
437 max_P = tb[TCA_CHOKE_MAX_P] ? nla_get_u32(tb[TCA_CHOKE_MAX_P]) : 0;
438
439 ctl = nla_data(tb[TCA_CHOKE_PARMS]);
440
441 if (ctl->limit > CHOKE_MAX_QUEUE)
442 return -EINVAL;
443
444 mask = roundup_pow_of_two(ctl->limit + 1) - 1;
445 if (mask != q->tab_mask) {
446 struct sk_buff **ntab;
447
448 ntab = kcalloc(mask + 1, sizeof(struct sk_buff *),
449 GFP_KERNEL | __GFP_NOWARN);
450 if (!ntab)
451 ntab = vzalloc((mask + 1) * sizeof(struct sk_buff *));
452 if (!ntab)
453 return -ENOMEM;
454
455 sch_tree_lock(sch);
456 old = q->tab;
457 if (old) {
458 unsigned int oqlen = sch->q.qlen, tail = 0;
459 unsigned dropped = 0;
460
461 while (q->head != q->tail) {
462 struct sk_buff *skb = q->tab[q->head];
463
464 q->head = (q->head + 1) & q->tab_mask;
465 if (!skb)
466 continue;
467 if (tail < mask) {
468 ntab[tail++] = skb;
469 continue;
470 }
471 dropped += qdisc_pkt_len(skb);
472 qdisc_qstats_backlog_dec(sch, skb);
473 --sch->q.qlen;
474 qdisc_drop(skb, sch);
475 }
476 qdisc_tree_reduce_backlog(sch, oqlen - sch->q.qlen, dropped);
477 q->head = 0;
478 q->tail = tail;
479 }
480
481 q->tab_mask = mask;
482 q->tab = ntab;
483 } else
484 sch_tree_lock(sch);
485
486 q->flags = ctl->flags;
487 q->limit = ctl->limit;
488
489 red_set_parms(&q->parms, ctl->qth_min, ctl->qth_max, ctl->Wlog,
490 ctl->Plog, ctl->Scell_log,
491 nla_data(tb[TCA_CHOKE_STAB]),
492 max_P);
493 red_set_vars(&q->vars);
494
495 if (q->head == q->tail)
496 red_end_of_idle_period(&q->vars);
497
498 sch_tree_unlock(sch);
499 choke_free(old);
500 return 0;
501}
502
503static int choke_init(struct Qdisc *sch, struct nlattr *opt)
504{
505 return choke_change(sch, opt);
506}
507
508static int choke_dump(struct Qdisc *sch, struct sk_buff *skb)
509{
510 struct choke_sched_data *q = qdisc_priv(sch);
511 struct nlattr *opts = NULL;
512 struct tc_red_qopt opt = {
513 .limit = q->limit,
514 .flags = q->flags,
515 .qth_min = q->parms.qth_min >> q->parms.Wlog,
516 .qth_max = q->parms.qth_max >> q->parms.Wlog,
517 .Wlog = q->parms.Wlog,
518 .Plog = q->parms.Plog,
519 .Scell_log = q->parms.Scell_log,
520 };
521
522 opts = nla_nest_start(skb, TCA_OPTIONS);
523 if (opts == NULL)
524 goto nla_put_failure;
525
526 if (nla_put(skb, TCA_CHOKE_PARMS, sizeof(opt), &opt) ||
527 nla_put_u32(skb, TCA_CHOKE_MAX_P, q->parms.max_P))
528 goto nla_put_failure;
529 return nla_nest_end(skb, opts);
530
531nla_put_failure:
532 nla_nest_cancel(skb, opts);
533 return -EMSGSIZE;
534}
535
536static int choke_dump_stats(struct Qdisc *sch, struct gnet_dump *d)
537{
538 struct choke_sched_data *q = qdisc_priv(sch);
539 struct tc_choke_xstats st = {
540 .early = q->stats.prob_drop + q->stats.forced_drop,
541 .marked = q->stats.prob_mark + q->stats.forced_mark,
542 .pdrop = q->stats.pdrop,
543 .other = q->stats.other,
544 .matched = q->stats.matched,
545 };
546
547 return gnet_stats_copy_app(d, &st, sizeof(st));
548}
549
550static void choke_destroy(struct Qdisc *sch)
551{
552 struct choke_sched_data *q = qdisc_priv(sch);
553
554 tcf_destroy_chain(&q->filter_list);
555 choke_free(q->tab);
556}
557
558static struct sk_buff *choke_peek_head(struct Qdisc *sch)
559{
560 struct choke_sched_data *q = qdisc_priv(sch);
561
562 return (q->head != q->tail) ? q->tab[q->head] : NULL;
563}
564
565static struct Qdisc_ops choke_qdisc_ops __read_mostly = {
566 .id = "choke",
567 .priv_size = sizeof(struct choke_sched_data),
568
569 .enqueue = choke_enqueue,
570 .dequeue = choke_dequeue,
571 .peek = choke_peek_head,
572 .drop = choke_drop,
573 .init = choke_init,
574 .destroy = choke_destroy,
575 .reset = choke_reset,
576 .change = choke_change,
577 .dump = choke_dump,
578 .dump_stats = choke_dump_stats,
579 .owner = THIS_MODULE,
580};
581
582static int __init choke_module_init(void)
583{
584 return register_qdisc(&choke_qdisc_ops);
585}
586
587static void __exit choke_module_exit(void)
588{
589 unregister_qdisc(&choke_qdisc_ops);
590}
591
592module_init(choke_module_init)
593module_exit(choke_module_exit)
594
595MODULE_LICENSE("GPL");
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/inet_ecn.h>
20#include <net/red.h>
21#include <net/flow_keys.h>
22
23/*
24 CHOKe stateless AQM for fair bandwidth allocation
25 =================================================
26
27 CHOKe (CHOose and Keep for responsive flows, CHOose and Kill for
28 unresponsive flows) is a variant of RED that penalizes misbehaving flows but
29 maintains no flow state. The difference from RED is an additional step
30 during the enqueuing process. If average queue size is over the
31 low threshold (qmin), a packet is chosen at random from the queue.
32 If both the new and chosen packet are from the same flow, both
33 are dropped. Unlike RED, CHOKe is not really a "classful" qdisc because it
34 needs to access packets in queue randomly. It has a minimal class
35 interface to allow overriding the builtin flow classifier with
36 filters.
37
38 Source:
39 R. Pan, B. Prabhakar, and K. Psounis, "CHOKe, A Stateless
40 Active Queue Management Scheme for Approximating Fair Bandwidth Allocation",
41 IEEE INFOCOM, 2000.
42
43 A. Tang, J. Wang, S. Low, "Understanding CHOKe: Throughput and Spatial
44 Characteristics", IEEE/ACM Transactions on Networking, 2004
45
46 */
47
48/* Upper bound on size of sk_buff table (packets) */
49#define CHOKE_MAX_QUEUE (128*1024 - 1)
50
51struct choke_sched_data {
52/* Parameters */
53 u32 limit;
54 unsigned char flags;
55
56 struct red_parms parms;
57
58/* Variables */
59 struct red_vars vars;
60 struct tcf_proto *filter_list;
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 */
80static 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 */
86static 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) */
92static 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 */
98static 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 */
108static 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" */
118static void choke_drop_by_idx(struct Qdisc *sch, unsigned int idx)
119{
120 struct choke_sched_data *q = qdisc_priv(sch);
121 struct sk_buff *skb = q->tab[idx];
122
123 q->tab[idx] = NULL;
124
125 if (idx == q->head)
126 choke_zap_head_holes(q);
127 if (idx == q->tail)
128 choke_zap_tail_holes(q);
129
130 sch->qstats.backlog -= qdisc_pkt_len(skb);
131 qdisc_drop(skb, sch);
132 qdisc_tree_decrease_qlen(sch, 1);
133 --sch->q.qlen;
134}
135
136struct choke_skb_cb {
137 u16 classid;
138 u8 keys_valid;
139 struct flow_keys keys;
140};
141
142static inline struct choke_skb_cb *choke_skb_cb(const struct sk_buff *skb)
143{
144 qdisc_cb_private_validate(skb, sizeof(struct choke_skb_cb));
145 return (struct choke_skb_cb *)qdisc_skb_cb(skb)->data;
146}
147
148static inline void choke_set_classid(struct sk_buff *skb, u16 classid)
149{
150 choke_skb_cb(skb)->classid = classid;
151}
152
153static u16 choke_get_classid(const struct sk_buff *skb)
154{
155 return choke_skb_cb(skb)->classid;
156}
157
158/*
159 * Compare flow of two packets
160 * Returns true only if source and destination address and port match.
161 * false for special cases
162 */
163static bool choke_match_flow(struct sk_buff *skb1,
164 struct sk_buff *skb2)
165{
166 if (skb1->protocol != skb2->protocol)
167 return false;
168
169 if (!choke_skb_cb(skb1)->keys_valid) {
170 choke_skb_cb(skb1)->keys_valid = 1;
171 skb_flow_dissect(skb1, &choke_skb_cb(skb1)->keys);
172 }
173
174 if (!choke_skb_cb(skb2)->keys_valid) {
175 choke_skb_cb(skb2)->keys_valid = 1;
176 skb_flow_dissect(skb2, &choke_skb_cb(skb2)->keys);
177 }
178
179 return !memcmp(&choke_skb_cb(skb1)->keys,
180 &choke_skb_cb(skb2)->keys,
181 sizeof(struct flow_keys));
182}
183
184/*
185 * Classify flow using either:
186 * 1. pre-existing classification result in skb
187 * 2. fast internal classification
188 * 3. use TC filter based classification
189 */
190static bool choke_classify(struct sk_buff *skb,
191 struct Qdisc *sch, int *qerr)
192
193{
194 struct choke_sched_data *q = qdisc_priv(sch);
195 struct tcf_result res;
196 int result;
197
198 result = tc_classify(skb, q->filter_list, &res);
199 if (result >= 0) {
200#ifdef CONFIG_NET_CLS_ACT
201 switch (result) {
202 case TC_ACT_STOLEN:
203 case TC_ACT_QUEUED:
204 *qerr = NET_XMIT_SUCCESS | __NET_XMIT_STOLEN;
205 case TC_ACT_SHOT:
206 return false;
207 }
208#endif
209 choke_set_classid(skb, TC_H_MIN(res.classid));
210 return true;
211 }
212
213 return false;
214}
215
216/*
217 * Select a packet at random from queue
218 * HACK: since queue can have holes from previous deletion; retry several
219 * times to find a random skb but then just give up and return the head
220 * Will return NULL if queue is empty (q->head == q->tail)
221 */
222static struct sk_buff *choke_peek_random(const struct choke_sched_data *q,
223 unsigned int *pidx)
224{
225 struct sk_buff *skb;
226 int retrys = 3;
227
228 do {
229 *pidx = (q->head + prandom_u32_max(choke_len(q))) & q->tab_mask;
230 skb = q->tab[*pidx];
231 if (skb)
232 return skb;
233 } while (--retrys > 0);
234
235 return q->tab[*pidx = q->head];
236}
237
238/*
239 * Compare new packet with random packet in queue
240 * returns true if matched and sets *pidx
241 */
242static bool choke_match_random(const struct choke_sched_data *q,
243 struct sk_buff *nskb,
244 unsigned int *pidx)
245{
246 struct sk_buff *oskb;
247
248 if (q->head == q->tail)
249 return false;
250
251 oskb = choke_peek_random(q, pidx);
252 if (q->filter_list)
253 return choke_get_classid(nskb) == choke_get_classid(oskb);
254
255 return choke_match_flow(oskb, nskb);
256}
257
258static int choke_enqueue(struct sk_buff *skb, struct Qdisc *sch)
259{
260 struct choke_sched_data *q = qdisc_priv(sch);
261 const struct red_parms *p = &q->parms;
262 int ret = NET_XMIT_SUCCESS | __NET_XMIT_BYPASS;
263
264 if (q->filter_list) {
265 /* If using external classifiers, get result and record it. */
266 if (!choke_classify(skb, sch, &ret))
267 goto other_drop; /* Packet was eaten by filter */
268 }
269
270 choke_skb_cb(skb)->keys_valid = 0;
271 /* Compute average queue usage (see RED) */
272 q->vars.qavg = red_calc_qavg(p, &q->vars, sch->q.qlen);
273 if (red_is_idling(&q->vars))
274 red_end_of_idle_period(&q->vars);
275
276 /* Is queue small? */
277 if (q->vars.qavg <= p->qth_min)
278 q->vars.qcount = -1;
279 else {
280 unsigned int idx;
281
282 /* Draw a packet at random from queue and compare flow */
283 if (choke_match_random(q, skb, &idx)) {
284 q->stats.matched++;
285 choke_drop_by_idx(sch, idx);
286 goto congestion_drop;
287 }
288
289 /* Queue is large, always mark/drop */
290 if (q->vars.qavg > p->qth_max) {
291 q->vars.qcount = -1;
292
293 sch->qstats.overlimits++;
294 if (use_harddrop(q) || !use_ecn(q) ||
295 !INET_ECN_set_ce(skb)) {
296 q->stats.forced_drop++;
297 goto congestion_drop;
298 }
299
300 q->stats.forced_mark++;
301 } else if (++q->vars.qcount) {
302 if (red_mark_probability(p, &q->vars, q->vars.qavg)) {
303 q->vars.qcount = 0;
304 q->vars.qR = red_random(p);
305
306 sch->qstats.overlimits++;
307 if (!use_ecn(q) || !INET_ECN_set_ce(skb)) {
308 q->stats.prob_drop++;
309 goto congestion_drop;
310 }
311
312 q->stats.prob_mark++;
313 }
314 } else
315 q->vars.qR = red_random(p);
316 }
317
318 /* Admit new packet */
319 if (sch->q.qlen < q->limit) {
320 q->tab[q->tail] = skb;
321 q->tail = (q->tail + 1) & q->tab_mask;
322 ++sch->q.qlen;
323 sch->qstats.backlog += qdisc_pkt_len(skb);
324 return NET_XMIT_SUCCESS;
325 }
326
327 q->stats.pdrop++;
328 return qdisc_drop(skb, sch);
329
330congestion_drop:
331 qdisc_drop(skb, sch);
332 return NET_XMIT_CN;
333
334other_drop:
335 if (ret & __NET_XMIT_BYPASS)
336 sch->qstats.drops++;
337 kfree_skb(skb);
338 return ret;
339}
340
341static struct sk_buff *choke_dequeue(struct Qdisc *sch)
342{
343 struct choke_sched_data *q = qdisc_priv(sch);
344 struct sk_buff *skb;
345
346 if (q->head == q->tail) {
347 if (!red_is_idling(&q->vars))
348 red_start_of_idle_period(&q->vars);
349 return NULL;
350 }
351
352 skb = q->tab[q->head];
353 q->tab[q->head] = NULL;
354 choke_zap_head_holes(q);
355 --sch->q.qlen;
356 sch->qstats.backlog -= qdisc_pkt_len(skb);
357 qdisc_bstats_update(sch, skb);
358
359 return skb;
360}
361
362static unsigned int choke_drop(struct Qdisc *sch)
363{
364 struct choke_sched_data *q = qdisc_priv(sch);
365 unsigned int len;
366
367 len = qdisc_queue_drop(sch);
368 if (len > 0)
369 q->stats.other++;
370 else {
371 if (!red_is_idling(&q->vars))
372 red_start_of_idle_period(&q->vars);
373 }
374
375 return len;
376}
377
378static void choke_reset(struct Qdisc *sch)
379{
380 struct choke_sched_data *q = qdisc_priv(sch);
381
382 red_restart(&q->vars);
383}
384
385static const struct nla_policy choke_policy[TCA_CHOKE_MAX + 1] = {
386 [TCA_CHOKE_PARMS] = { .len = sizeof(struct tc_red_qopt) },
387 [TCA_CHOKE_STAB] = { .len = RED_STAB_SIZE },
388 [TCA_CHOKE_MAX_P] = { .type = NLA_U32 },
389};
390
391
392static void choke_free(void *addr)
393{
394 if (addr) {
395 if (is_vmalloc_addr(addr))
396 vfree(addr);
397 else
398 kfree(addr);
399 }
400}
401
402static int choke_change(struct Qdisc *sch, struct nlattr *opt)
403{
404 struct choke_sched_data *q = qdisc_priv(sch);
405 struct nlattr *tb[TCA_CHOKE_MAX + 1];
406 const struct tc_red_qopt *ctl;
407 int err;
408 struct sk_buff **old = NULL;
409 unsigned int mask;
410 u32 max_P;
411
412 if (opt == NULL)
413 return -EINVAL;
414
415 err = nla_parse_nested(tb, TCA_CHOKE_MAX, opt, choke_policy);
416 if (err < 0)
417 return err;
418
419 if (tb[TCA_CHOKE_PARMS] == NULL ||
420 tb[TCA_CHOKE_STAB] == NULL)
421 return -EINVAL;
422
423 max_P = tb[TCA_CHOKE_MAX_P] ? nla_get_u32(tb[TCA_CHOKE_MAX_P]) : 0;
424
425 ctl = nla_data(tb[TCA_CHOKE_PARMS]);
426
427 if (ctl->limit > CHOKE_MAX_QUEUE)
428 return -EINVAL;
429
430 mask = roundup_pow_of_two(ctl->limit + 1) - 1;
431 if (mask != q->tab_mask) {
432 struct sk_buff **ntab;
433
434 ntab = kcalloc(mask + 1, sizeof(struct sk_buff *),
435 GFP_KERNEL | __GFP_NOWARN);
436 if (!ntab)
437 ntab = vzalloc((mask + 1) * sizeof(struct sk_buff *));
438 if (!ntab)
439 return -ENOMEM;
440
441 sch_tree_lock(sch);
442 old = q->tab;
443 if (old) {
444 unsigned int oqlen = sch->q.qlen, tail = 0;
445
446 while (q->head != q->tail) {
447 struct sk_buff *skb = q->tab[q->head];
448
449 q->head = (q->head + 1) & q->tab_mask;
450 if (!skb)
451 continue;
452 if (tail < mask) {
453 ntab[tail++] = skb;
454 continue;
455 }
456 sch->qstats.backlog -= qdisc_pkt_len(skb);
457 --sch->q.qlen;
458 qdisc_drop(skb, sch);
459 }
460 qdisc_tree_decrease_qlen(sch, oqlen - sch->q.qlen);
461 q->head = 0;
462 q->tail = tail;
463 }
464
465 q->tab_mask = mask;
466 q->tab = ntab;
467 } else
468 sch_tree_lock(sch);
469
470 q->flags = ctl->flags;
471 q->limit = ctl->limit;
472
473 red_set_parms(&q->parms, ctl->qth_min, ctl->qth_max, ctl->Wlog,
474 ctl->Plog, ctl->Scell_log,
475 nla_data(tb[TCA_CHOKE_STAB]),
476 max_P);
477 red_set_vars(&q->vars);
478
479 if (q->head == q->tail)
480 red_end_of_idle_period(&q->vars);
481
482 sch_tree_unlock(sch);
483 choke_free(old);
484 return 0;
485}
486
487static int choke_init(struct Qdisc *sch, struct nlattr *opt)
488{
489 return choke_change(sch, opt);
490}
491
492static int choke_dump(struct Qdisc *sch, struct sk_buff *skb)
493{
494 struct choke_sched_data *q = qdisc_priv(sch);
495 struct nlattr *opts = NULL;
496 struct tc_red_qopt opt = {
497 .limit = q->limit,
498 .flags = q->flags,
499 .qth_min = q->parms.qth_min >> q->parms.Wlog,
500 .qth_max = q->parms.qth_max >> q->parms.Wlog,
501 .Wlog = q->parms.Wlog,
502 .Plog = q->parms.Plog,
503 .Scell_log = q->parms.Scell_log,
504 };
505
506 opts = nla_nest_start(skb, TCA_OPTIONS);
507 if (opts == NULL)
508 goto nla_put_failure;
509
510 if (nla_put(skb, TCA_CHOKE_PARMS, sizeof(opt), &opt) ||
511 nla_put_u32(skb, TCA_CHOKE_MAX_P, q->parms.max_P))
512 goto nla_put_failure;
513 return nla_nest_end(skb, opts);
514
515nla_put_failure:
516 nla_nest_cancel(skb, opts);
517 return -EMSGSIZE;
518}
519
520static int choke_dump_stats(struct Qdisc *sch, struct gnet_dump *d)
521{
522 struct choke_sched_data *q = qdisc_priv(sch);
523 struct tc_choke_xstats st = {
524 .early = q->stats.prob_drop + q->stats.forced_drop,
525 .marked = q->stats.prob_mark + q->stats.forced_mark,
526 .pdrop = q->stats.pdrop,
527 .other = q->stats.other,
528 .matched = q->stats.matched,
529 };
530
531 return gnet_stats_copy_app(d, &st, sizeof(st));
532}
533
534static void choke_destroy(struct Qdisc *sch)
535{
536 struct choke_sched_data *q = qdisc_priv(sch);
537
538 tcf_destroy_chain(&q->filter_list);
539 choke_free(q->tab);
540}
541
542static struct Qdisc *choke_leaf(struct Qdisc *sch, unsigned long arg)
543{
544 return NULL;
545}
546
547static unsigned long choke_get(struct Qdisc *sch, u32 classid)
548{
549 return 0;
550}
551
552static void choke_put(struct Qdisc *q, unsigned long cl)
553{
554}
555
556static unsigned long choke_bind(struct Qdisc *sch, unsigned long parent,
557 u32 classid)
558{
559 return 0;
560}
561
562static struct tcf_proto **choke_find_tcf(struct Qdisc *sch, unsigned long cl)
563{
564 struct choke_sched_data *q = qdisc_priv(sch);
565
566 if (cl)
567 return NULL;
568 return &q->filter_list;
569}
570
571static int choke_dump_class(struct Qdisc *sch, unsigned long cl,
572 struct sk_buff *skb, struct tcmsg *tcm)
573{
574 tcm->tcm_handle |= TC_H_MIN(cl);
575 return 0;
576}
577
578static void choke_walk(struct Qdisc *sch, struct qdisc_walker *arg)
579{
580 if (!arg->stop) {
581 if (arg->fn(sch, 1, arg) < 0) {
582 arg->stop = 1;
583 return;
584 }
585 arg->count++;
586 }
587}
588
589static const struct Qdisc_class_ops choke_class_ops = {
590 .leaf = choke_leaf,
591 .get = choke_get,
592 .put = choke_put,
593 .tcf_chain = choke_find_tcf,
594 .bind_tcf = choke_bind,
595 .unbind_tcf = choke_put,
596 .dump = choke_dump_class,
597 .walk = choke_walk,
598};
599
600static struct sk_buff *choke_peek_head(struct Qdisc *sch)
601{
602 struct choke_sched_data *q = qdisc_priv(sch);
603
604 return (q->head != q->tail) ? q->tab[q->head] : NULL;
605}
606
607static struct Qdisc_ops choke_qdisc_ops __read_mostly = {
608 .id = "choke",
609 .priv_size = sizeof(struct choke_sched_data),
610
611 .enqueue = choke_enqueue,
612 .dequeue = choke_dequeue,
613 .peek = choke_peek_head,
614 .drop = choke_drop,
615 .init = choke_init,
616 .destroy = choke_destroy,
617 .reset = choke_reset,
618 .change = choke_change,
619 .dump = choke_dump,
620 .dump_stats = choke_dump_stats,
621 .owner = THIS_MODULE,
622};
623
624static int __init choke_module_init(void)
625{
626 return register_qdisc(&choke_qdisc_ops);
627}
628
629static void __exit choke_module_exit(void)
630{
631 unregister_qdisc(&choke_qdisc_ops);
632}
633
634module_init(choke_module_init)
635module_exit(choke_module_exit)
636
637MODULE_LICENSE("GPL");