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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// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * net/sched/sch_choke.c CHOKE scheduler
4 *
5 * Copyright (c) 2011 Stephen Hemminger <shemminger@vyatta.com>
6 * Copyright (c) 2011 Eric Dumazet <eric.dumazet@gmail.com>
7 */
8
9#include <linux/module.h>
10#include <linux/types.h>
11#include <linux/kernel.h>
12#include <linux/skbuff.h>
13#include <linux/vmalloc.h>
14#include <net/pkt_sched.h>
15#include <net/pkt_cls.h>
16#include <net/inet_ecn.h>
17#include <net/red.h>
18#include <net/flow_dissector.h>
19
20/*
21 CHOKe stateless AQM for fair bandwidth allocation
22 =================================================
23
24 CHOKe (CHOose and Keep for responsive flows, CHOose and Kill for
25 unresponsive flows) is a variant of RED that penalizes misbehaving flows but
26 maintains no flow state. The difference from RED is an additional step
27 during the enqueuing process. If average queue size is over the
28 low threshold (qmin), a packet is chosen at random from the queue.
29 If both the new and chosen packet are from the same flow, both
30 are dropped. Unlike RED, CHOKe is not really a "classful" qdisc because it
31 needs to access packets in queue randomly. It has a minimal class
32 interface to allow overriding the builtin flow classifier with
33 filters.
34
35 Source:
36 R. Pan, B. Prabhakar, and K. Psounis, "CHOKe, A Stateless
37 Active Queue Management Scheme for Approximating Fair Bandwidth Allocation",
38 IEEE INFOCOM, 2000.
39
40 A. Tang, J. Wang, S. Low, "Understanding CHOKe: Throughput and Spatial
41 Characteristics", IEEE/ACM Transactions on Networking, 2004
42
43 */
44
45/* Upper bound on size of sk_buff table (packets) */
46#define CHOKE_MAX_QUEUE (128*1024 - 1)
47
48struct choke_sched_data {
49/* Parameters */
50 u32 limit;
51 unsigned char flags;
52
53 struct red_parms parms;
54
55/* Variables */
56 struct red_vars vars;
57 struct {
58 u32 prob_drop; /* Early probability drops */
59 u32 prob_mark; /* Early probability marks */
60 u32 forced_drop; /* Forced drops, qavg > max_thresh */
61 u32 forced_mark; /* Forced marks, qavg > max_thresh */
62 u32 pdrop; /* Drops due to queue limits */
63 u32 matched; /* Drops to flow match */
64 } stats;
65
66 unsigned int head;
67 unsigned int tail;
68
69 unsigned int tab_mask; /* size - 1 */
70
71 struct sk_buff **tab;
72};
73
74/* number of elements in queue including holes */
75static unsigned int choke_len(const struct choke_sched_data *q)
76{
77 return (q->tail - q->head) & q->tab_mask;
78}
79
80/* Is ECN parameter configured */
81static int use_ecn(const struct choke_sched_data *q)
82{
83 return q->flags & TC_RED_ECN;
84}
85
86/* Should packets over max just be dropped (versus marked) */
87static int use_harddrop(const struct choke_sched_data *q)
88{
89 return q->flags & TC_RED_HARDDROP;
90}
91
92/* Move head pointer forward to skip over holes */
93static void choke_zap_head_holes(struct choke_sched_data *q)
94{
95 do {
96 q->head = (q->head + 1) & q->tab_mask;
97 if (q->head == q->tail)
98 break;
99 } while (q->tab[q->head] == NULL);
100}
101
102/* Move tail pointer backwards to reuse holes */
103static void choke_zap_tail_holes(struct choke_sched_data *q)
104{
105 do {
106 q->tail = (q->tail - 1) & q->tab_mask;
107 if (q->head == q->tail)
108 break;
109 } while (q->tab[q->tail] == NULL);
110}
111
112/* Drop packet from queue array by creating a "hole" */
113static void choke_drop_by_idx(struct Qdisc *sch, unsigned int idx,
114 struct sk_buff **to_free)
115{
116 struct choke_sched_data *q = qdisc_priv(sch);
117 struct sk_buff *skb = q->tab[idx];
118
119 q->tab[idx] = NULL;
120
121 if (idx == q->head)
122 choke_zap_head_holes(q);
123 if (idx == q->tail)
124 choke_zap_tail_holes(q);
125
126 --sch->q.qlen;
127 qdisc_qstats_backlog_dec(sch, skb);
128 qdisc_tree_reduce_backlog(sch, 1, qdisc_pkt_len(skb));
129 qdisc_drop(skb, sch, to_free);
130}
131
132struct choke_skb_cb {
133 u8 keys_valid;
134 struct flow_keys_digest keys;
135};
136
137static inline struct choke_skb_cb *choke_skb_cb(const struct sk_buff *skb)
138{
139 qdisc_cb_private_validate(skb, sizeof(struct choke_skb_cb));
140 return (struct choke_skb_cb *)qdisc_skb_cb(skb)->data;
141}
142
143/*
144 * Compare flow of two packets
145 * Returns true only if source and destination address and port match.
146 * false for special cases
147 */
148static bool choke_match_flow(struct sk_buff *skb1,
149 struct sk_buff *skb2)
150{
151 struct flow_keys temp;
152
153 if (skb1->protocol != skb2->protocol)
154 return false;
155
156 if (!choke_skb_cb(skb1)->keys_valid) {
157 choke_skb_cb(skb1)->keys_valid = 1;
158 skb_flow_dissect_flow_keys(skb1, &temp, 0);
159 make_flow_keys_digest(&choke_skb_cb(skb1)->keys, &temp);
160 }
161
162 if (!choke_skb_cb(skb2)->keys_valid) {
163 choke_skb_cb(skb2)->keys_valid = 1;
164 skb_flow_dissect_flow_keys(skb2, &temp, 0);
165 make_flow_keys_digest(&choke_skb_cb(skb2)->keys, &temp);
166 }
167
168 return !memcmp(&choke_skb_cb(skb1)->keys,
169 &choke_skb_cb(skb2)->keys,
170 sizeof(choke_skb_cb(skb1)->keys));
171}
172
173/*
174 * Select a packet at random from queue
175 * HACK: since queue can have holes from previous deletion; retry several
176 * times to find a random skb but then just give up and return the head
177 * Will return NULL if queue is empty (q->head == q->tail)
178 */
179static struct sk_buff *choke_peek_random(const struct choke_sched_data *q,
180 unsigned int *pidx)
181{
182 struct sk_buff *skb;
183 int retrys = 3;
184
185 do {
186 *pidx = (q->head + get_random_u32_below(choke_len(q))) & q->tab_mask;
187 skb = q->tab[*pidx];
188 if (skb)
189 return skb;
190 } while (--retrys > 0);
191
192 return q->tab[*pidx = q->head];
193}
194
195/*
196 * Compare new packet with random packet in queue
197 * returns true if matched and sets *pidx
198 */
199static bool choke_match_random(const struct choke_sched_data *q,
200 struct sk_buff *nskb,
201 unsigned int *pidx)
202{
203 struct sk_buff *oskb;
204
205 if (q->head == q->tail)
206 return false;
207
208 oskb = choke_peek_random(q, pidx);
209 return choke_match_flow(oskb, nskb);
210}
211
212static int choke_enqueue(struct sk_buff *skb, struct Qdisc *sch,
213 struct sk_buff **to_free)
214{
215 struct choke_sched_data *q = qdisc_priv(sch);
216 const struct red_parms *p = &q->parms;
217
218 choke_skb_cb(skb)->keys_valid = 0;
219 /* Compute average queue usage (see RED) */
220 q->vars.qavg = red_calc_qavg(p, &q->vars, sch->q.qlen);
221 if (red_is_idling(&q->vars))
222 red_end_of_idle_period(&q->vars);
223
224 /* Is queue small? */
225 if (q->vars.qavg <= p->qth_min)
226 q->vars.qcount = -1;
227 else {
228 unsigned int idx;
229
230 /* Draw a packet at random from queue and compare flow */
231 if (choke_match_random(q, skb, &idx)) {
232 q->stats.matched++;
233 choke_drop_by_idx(sch, idx, to_free);
234 goto congestion_drop;
235 }
236
237 /* Queue is large, always mark/drop */
238 if (q->vars.qavg > p->qth_max) {
239 q->vars.qcount = -1;
240
241 qdisc_qstats_overlimit(sch);
242 if (use_harddrop(q) || !use_ecn(q) ||
243 !INET_ECN_set_ce(skb)) {
244 q->stats.forced_drop++;
245 goto congestion_drop;
246 }
247
248 q->stats.forced_mark++;
249 } else if (++q->vars.qcount) {
250 if (red_mark_probability(p, &q->vars, q->vars.qavg)) {
251 q->vars.qcount = 0;
252 q->vars.qR = red_random(p);
253
254 qdisc_qstats_overlimit(sch);
255 if (!use_ecn(q) || !INET_ECN_set_ce(skb)) {
256 q->stats.prob_drop++;
257 goto congestion_drop;
258 }
259
260 q->stats.prob_mark++;
261 }
262 } else
263 q->vars.qR = red_random(p);
264 }
265
266 /* Admit new packet */
267 if (sch->q.qlen < q->limit) {
268 q->tab[q->tail] = skb;
269 q->tail = (q->tail + 1) & q->tab_mask;
270 ++sch->q.qlen;
271 qdisc_qstats_backlog_inc(sch, skb);
272 return NET_XMIT_SUCCESS;
273 }
274
275 q->stats.pdrop++;
276 return qdisc_drop(skb, sch, to_free);
277
278congestion_drop:
279 qdisc_drop(skb, sch, to_free);
280 return NET_XMIT_CN;
281}
282
283static struct sk_buff *choke_dequeue(struct Qdisc *sch)
284{
285 struct choke_sched_data *q = qdisc_priv(sch);
286 struct sk_buff *skb;
287
288 if (q->head == q->tail) {
289 if (!red_is_idling(&q->vars))
290 red_start_of_idle_period(&q->vars);
291 return NULL;
292 }
293
294 skb = q->tab[q->head];
295 q->tab[q->head] = NULL;
296 choke_zap_head_holes(q);
297 --sch->q.qlen;
298 qdisc_qstats_backlog_dec(sch, skb);
299 qdisc_bstats_update(sch, skb);
300
301 return skb;
302}
303
304static void choke_reset(struct Qdisc *sch)
305{
306 struct choke_sched_data *q = qdisc_priv(sch);
307
308 while (q->head != q->tail) {
309 struct sk_buff *skb = q->tab[q->head];
310
311 q->head = (q->head + 1) & q->tab_mask;
312 if (!skb)
313 continue;
314 rtnl_qdisc_drop(skb, sch);
315 }
316
317 if (q->tab)
318 memset(q->tab, 0, (q->tab_mask + 1) * sizeof(struct sk_buff *));
319 q->head = q->tail = 0;
320 red_restart(&q->vars);
321}
322
323static const struct nla_policy choke_policy[TCA_CHOKE_MAX + 1] = {
324 [TCA_CHOKE_PARMS] = { .len = sizeof(struct tc_red_qopt) },
325 [TCA_CHOKE_STAB] = { .len = RED_STAB_SIZE },
326 [TCA_CHOKE_MAX_P] = { .type = NLA_U32 },
327};
328
329
330static void choke_free(void *addr)
331{
332 kvfree(addr);
333}
334
335static int choke_change(struct Qdisc *sch, struct nlattr *opt,
336 struct netlink_ext_ack *extack)
337{
338 struct choke_sched_data *q = qdisc_priv(sch);
339 struct nlattr *tb[TCA_CHOKE_MAX + 1];
340 const struct tc_red_qopt *ctl;
341 int err;
342 struct sk_buff **old = NULL;
343 unsigned int mask;
344 u32 max_P;
345 u8 *stab;
346
347 if (opt == NULL)
348 return -EINVAL;
349
350 err = nla_parse_nested_deprecated(tb, TCA_CHOKE_MAX, opt,
351 choke_policy, NULL);
352 if (err < 0)
353 return err;
354
355 if (tb[TCA_CHOKE_PARMS] == NULL ||
356 tb[TCA_CHOKE_STAB] == NULL)
357 return -EINVAL;
358
359 max_P = nla_get_u32_default(tb[TCA_CHOKE_MAX_P], 0);
360
361 ctl = nla_data(tb[TCA_CHOKE_PARMS]);
362 stab = nla_data(tb[TCA_CHOKE_STAB]);
363 if (!red_check_params(ctl->qth_min, ctl->qth_max, ctl->Wlog, ctl->Scell_log, stab))
364 return -EINVAL;
365
366 if (ctl->limit > CHOKE_MAX_QUEUE)
367 return -EINVAL;
368
369 mask = roundup_pow_of_two(ctl->limit + 1) - 1;
370 if (mask != q->tab_mask) {
371 struct sk_buff **ntab;
372
373 ntab = kvcalloc(mask + 1, sizeof(struct sk_buff *), GFP_KERNEL);
374 if (!ntab)
375 return -ENOMEM;
376
377 sch_tree_lock(sch);
378 old = q->tab;
379 if (old) {
380 unsigned int oqlen = sch->q.qlen, tail = 0;
381 unsigned dropped = 0;
382
383 while (q->head != q->tail) {
384 struct sk_buff *skb = q->tab[q->head];
385
386 q->head = (q->head + 1) & q->tab_mask;
387 if (!skb)
388 continue;
389 if (tail < mask) {
390 ntab[tail++] = skb;
391 continue;
392 }
393 dropped += qdisc_pkt_len(skb);
394 qdisc_qstats_backlog_dec(sch, skb);
395 --sch->q.qlen;
396 rtnl_qdisc_drop(skb, sch);
397 }
398 qdisc_tree_reduce_backlog(sch, oqlen - sch->q.qlen, dropped);
399 q->head = 0;
400 q->tail = tail;
401 }
402
403 q->tab_mask = mask;
404 q->tab = ntab;
405 } else
406 sch_tree_lock(sch);
407
408 WRITE_ONCE(q->flags, ctl->flags);
409 WRITE_ONCE(q->limit, ctl->limit);
410
411 red_set_parms(&q->parms, ctl->qth_min, ctl->qth_max, ctl->Wlog,
412 ctl->Plog, ctl->Scell_log,
413 stab,
414 max_P);
415 red_set_vars(&q->vars);
416
417 if (q->head == q->tail)
418 red_end_of_idle_period(&q->vars);
419
420 sch_tree_unlock(sch);
421 choke_free(old);
422 return 0;
423}
424
425static int choke_init(struct Qdisc *sch, struct nlattr *opt,
426 struct netlink_ext_ack *extack)
427{
428 return choke_change(sch, opt, extack);
429}
430
431static int choke_dump(struct Qdisc *sch, struct sk_buff *skb)
432{
433 struct choke_sched_data *q = qdisc_priv(sch);
434 u8 Wlog = READ_ONCE(q->parms.Wlog);
435 struct nlattr *opts = NULL;
436 struct tc_red_qopt opt = {
437 .limit = READ_ONCE(q->limit),
438 .flags = READ_ONCE(q->flags),
439 .qth_min = READ_ONCE(q->parms.qth_min) >> Wlog,
440 .qth_max = READ_ONCE(q->parms.qth_max) >> Wlog,
441 .Wlog = Wlog,
442 .Plog = READ_ONCE(q->parms.Plog),
443 .Scell_log = READ_ONCE(q->parms.Scell_log),
444 };
445
446 opts = nla_nest_start_noflag(skb, TCA_OPTIONS);
447 if (opts == NULL)
448 goto nla_put_failure;
449
450 if (nla_put(skb, TCA_CHOKE_PARMS, sizeof(opt), &opt) ||
451 nla_put_u32(skb, TCA_CHOKE_MAX_P, READ_ONCE(q->parms.max_P)))
452 goto nla_put_failure;
453 return nla_nest_end(skb, opts);
454
455nla_put_failure:
456 nla_nest_cancel(skb, opts);
457 return -EMSGSIZE;
458}
459
460static int choke_dump_stats(struct Qdisc *sch, struct gnet_dump *d)
461{
462 struct choke_sched_data *q = qdisc_priv(sch);
463 struct tc_choke_xstats st = {
464 .early = q->stats.prob_drop + q->stats.forced_drop,
465 .marked = q->stats.prob_mark + q->stats.forced_mark,
466 .pdrop = q->stats.pdrop,
467 .matched = q->stats.matched,
468 };
469
470 return gnet_stats_copy_app(d, &st, sizeof(st));
471}
472
473static void choke_destroy(struct Qdisc *sch)
474{
475 struct choke_sched_data *q = qdisc_priv(sch);
476
477 choke_free(q->tab);
478}
479
480static struct sk_buff *choke_peek_head(struct Qdisc *sch)
481{
482 struct choke_sched_data *q = qdisc_priv(sch);
483
484 return (q->head != q->tail) ? q->tab[q->head] : NULL;
485}
486
487static struct Qdisc_ops choke_qdisc_ops __read_mostly = {
488 .id = "choke",
489 .priv_size = sizeof(struct choke_sched_data),
490
491 .enqueue = choke_enqueue,
492 .dequeue = choke_dequeue,
493 .peek = choke_peek_head,
494 .init = choke_init,
495 .destroy = choke_destroy,
496 .reset = choke_reset,
497 .change = choke_change,
498 .dump = choke_dump,
499 .dump_stats = choke_dump_stats,
500 .owner = THIS_MODULE,
501};
502MODULE_ALIAS_NET_SCH("choke");
503
504static int __init choke_module_init(void)
505{
506 return register_qdisc(&choke_qdisc_ops);
507}
508
509static void __exit choke_module_exit(void)
510{
511 unregister_qdisc(&choke_qdisc_ops);
512}
513
514module_init(choke_module_init)
515module_exit(choke_module_exit)
516
517MODULE_LICENSE("GPL");
518MODULE_DESCRIPTION("Choose and keep responsive flows scheduler");