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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 other; /* Drops due to drop() calls */
64 u32 matched; /* Drops to flow match */
65 } stats;
66
67 unsigned int head;
68 unsigned int tail;
69
70 unsigned int tab_mask; /* size - 1 */
71
72 struct sk_buff **tab;
73};
74
75/* number of elements in queue including holes */
76static unsigned int choke_len(const struct choke_sched_data *q)
77{
78 return (q->tail - q->head) & q->tab_mask;
79}
80
81/* Is ECN parameter configured */
82static int use_ecn(const struct choke_sched_data *q)
83{
84 return q->flags & TC_RED_ECN;
85}
86
87/* Should packets over max just be dropped (versus marked) */
88static int use_harddrop(const struct choke_sched_data *q)
89{
90 return q->flags & TC_RED_HARDDROP;
91}
92
93/* Move head pointer forward to skip over holes */
94static void choke_zap_head_holes(struct choke_sched_data *q)
95{
96 do {
97 q->head = (q->head + 1) & q->tab_mask;
98 if (q->head == q->tail)
99 break;
100 } while (q->tab[q->head] == NULL);
101}
102
103/* Move tail pointer backwards to reuse holes */
104static void choke_zap_tail_holes(struct choke_sched_data *q)
105{
106 do {
107 q->tail = (q->tail - 1) & q->tab_mask;
108 if (q->head == q->tail)
109 break;
110 } while (q->tab[q->tail] == NULL);
111}
112
113/* Drop packet from queue array by creating a "hole" */
114static void choke_drop_by_idx(struct Qdisc *sch, unsigned int idx,
115 struct sk_buff **to_free)
116{
117 struct choke_sched_data *q = qdisc_priv(sch);
118 struct sk_buff *skb = q->tab[idx];
119
120 q->tab[idx] = NULL;
121
122 if (idx == q->head)
123 choke_zap_head_holes(q);
124 if (idx == q->tail)
125 choke_zap_tail_holes(q);
126
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 --sch->q.qlen;
131}
132
133struct choke_skb_cb {
134 u16 classid;
135 u8 keys_valid;
136 struct flow_keys_digest keys;
137};
138
139static inline struct choke_skb_cb *choke_skb_cb(const struct sk_buff *skb)
140{
141 qdisc_cb_private_validate(skb, sizeof(struct choke_skb_cb));
142 return (struct choke_skb_cb *)qdisc_skb_cb(skb)->data;
143}
144
145static inline void choke_set_classid(struct sk_buff *skb, u16 classid)
146{
147 choke_skb_cb(skb)->classid = classid;
148}
149
150/*
151 * Compare flow of two packets
152 * Returns true only if source and destination address and port match.
153 * false for special cases
154 */
155static bool choke_match_flow(struct sk_buff *skb1,
156 struct sk_buff *skb2)
157{
158 struct flow_keys temp;
159
160 if (skb1->protocol != skb2->protocol)
161 return false;
162
163 if (!choke_skb_cb(skb1)->keys_valid) {
164 choke_skb_cb(skb1)->keys_valid = 1;
165 skb_flow_dissect_flow_keys(skb1, &temp, 0);
166 make_flow_keys_digest(&choke_skb_cb(skb1)->keys, &temp);
167 }
168
169 if (!choke_skb_cb(skb2)->keys_valid) {
170 choke_skb_cb(skb2)->keys_valid = 1;
171 skb_flow_dissect_flow_keys(skb2, &temp, 0);
172 make_flow_keys_digest(&choke_skb_cb(skb2)->keys, &temp);
173 }
174
175 return !memcmp(&choke_skb_cb(skb1)->keys,
176 &choke_skb_cb(skb2)->keys,
177 sizeof(choke_skb_cb(skb1)->keys));
178}
179
180/*
181 * Select a packet at random from queue
182 * HACK: since queue can have holes from previous deletion; retry several
183 * times to find a random skb but then just give up and return the head
184 * Will return NULL if queue is empty (q->head == q->tail)
185 */
186static struct sk_buff *choke_peek_random(const struct choke_sched_data *q,
187 unsigned int *pidx)
188{
189 struct sk_buff *skb;
190 int retrys = 3;
191
192 do {
193 *pidx = (q->head + prandom_u32_max(choke_len(q))) & q->tab_mask;
194 skb = q->tab[*pidx];
195 if (skb)
196 return skb;
197 } while (--retrys > 0);
198
199 return q->tab[*pidx = q->head];
200}
201
202/*
203 * Compare new packet with random packet in queue
204 * returns true if matched and sets *pidx
205 */
206static bool choke_match_random(const struct choke_sched_data *q,
207 struct sk_buff *nskb,
208 unsigned int *pidx)
209{
210 struct sk_buff *oskb;
211
212 if (q->head == q->tail)
213 return false;
214
215 oskb = choke_peek_random(q, pidx);
216 return choke_match_flow(oskb, nskb);
217}
218
219static int choke_enqueue(struct sk_buff *skb, struct Qdisc *sch,
220 struct sk_buff **to_free)
221{
222 struct choke_sched_data *q = qdisc_priv(sch);
223 const struct red_parms *p = &q->parms;
224
225 choke_skb_cb(skb)->keys_valid = 0;
226 /* Compute average queue usage (see RED) */
227 q->vars.qavg = red_calc_qavg(p, &q->vars, sch->q.qlen);
228 if (red_is_idling(&q->vars))
229 red_end_of_idle_period(&q->vars);
230
231 /* Is queue small? */
232 if (q->vars.qavg <= p->qth_min)
233 q->vars.qcount = -1;
234 else {
235 unsigned int idx;
236
237 /* Draw a packet at random from queue and compare flow */
238 if (choke_match_random(q, skb, &idx)) {
239 q->stats.matched++;
240 choke_drop_by_idx(sch, idx, to_free);
241 goto congestion_drop;
242 }
243
244 /* Queue is large, always mark/drop */
245 if (q->vars.qavg > p->qth_max) {
246 q->vars.qcount = -1;
247
248 qdisc_qstats_overlimit(sch);
249 if (use_harddrop(q) || !use_ecn(q) ||
250 !INET_ECN_set_ce(skb)) {
251 q->stats.forced_drop++;
252 goto congestion_drop;
253 }
254
255 q->stats.forced_mark++;
256 } else if (++q->vars.qcount) {
257 if (red_mark_probability(p, &q->vars, q->vars.qavg)) {
258 q->vars.qcount = 0;
259 q->vars.qR = red_random(p);
260
261 qdisc_qstats_overlimit(sch);
262 if (!use_ecn(q) || !INET_ECN_set_ce(skb)) {
263 q->stats.prob_drop++;
264 goto congestion_drop;
265 }
266
267 q->stats.prob_mark++;
268 }
269 } else
270 q->vars.qR = red_random(p);
271 }
272
273 /* Admit new packet */
274 if (sch->q.qlen < q->limit) {
275 q->tab[q->tail] = skb;
276 q->tail = (q->tail + 1) & q->tab_mask;
277 ++sch->q.qlen;
278 qdisc_qstats_backlog_inc(sch, skb);
279 return NET_XMIT_SUCCESS;
280 }
281
282 q->stats.pdrop++;
283 return qdisc_drop(skb, sch, to_free);
284
285congestion_drop:
286 qdisc_drop(skb, sch, to_free);
287 return NET_XMIT_CN;
288}
289
290static struct sk_buff *choke_dequeue(struct Qdisc *sch)
291{
292 struct choke_sched_data *q = qdisc_priv(sch);
293 struct sk_buff *skb;
294
295 if (q->head == q->tail) {
296 if (!red_is_idling(&q->vars))
297 red_start_of_idle_period(&q->vars);
298 return NULL;
299 }
300
301 skb = q->tab[q->head];
302 q->tab[q->head] = NULL;
303 choke_zap_head_holes(q);
304 --sch->q.qlen;
305 qdisc_qstats_backlog_dec(sch, skb);
306 qdisc_bstats_update(sch, skb);
307
308 return skb;
309}
310
311static void choke_reset(struct Qdisc *sch)
312{
313 struct choke_sched_data *q = qdisc_priv(sch);
314
315 while (q->head != q->tail) {
316 struct sk_buff *skb = q->tab[q->head];
317
318 q->head = (q->head + 1) & q->tab_mask;
319 if (!skb)
320 continue;
321 rtnl_qdisc_drop(skb, sch);
322 }
323
324 sch->q.qlen = 0;
325 sch->qstats.backlog = 0;
326 memset(q->tab, 0, (q->tab_mask + 1) * sizeof(struct sk_buff *));
327 q->head = q->tail = 0;
328 red_restart(&q->vars);
329}
330
331static const struct nla_policy choke_policy[TCA_CHOKE_MAX + 1] = {
332 [TCA_CHOKE_PARMS] = { .len = sizeof(struct tc_red_qopt) },
333 [TCA_CHOKE_STAB] = { .len = RED_STAB_SIZE },
334 [TCA_CHOKE_MAX_P] = { .type = NLA_U32 },
335};
336
337
338static void choke_free(void *addr)
339{
340 kvfree(addr);
341}
342
343static int choke_change(struct Qdisc *sch, struct nlattr *opt,
344 struct netlink_ext_ack *extack)
345{
346 struct choke_sched_data *q = qdisc_priv(sch);
347 struct nlattr *tb[TCA_CHOKE_MAX + 1];
348 const struct tc_red_qopt *ctl;
349 int err;
350 struct sk_buff **old = NULL;
351 unsigned int mask;
352 u32 max_P;
353
354 if (opt == NULL)
355 return -EINVAL;
356
357 err = nla_parse_nested_deprecated(tb, TCA_CHOKE_MAX, opt,
358 choke_policy, NULL);
359 if (err < 0)
360 return err;
361
362 if (tb[TCA_CHOKE_PARMS] == NULL ||
363 tb[TCA_CHOKE_STAB] == NULL)
364 return -EINVAL;
365
366 max_P = tb[TCA_CHOKE_MAX_P] ? nla_get_u32(tb[TCA_CHOKE_MAX_P]) : 0;
367
368 ctl = nla_data(tb[TCA_CHOKE_PARMS]);
369
370 if (!red_check_params(ctl->qth_min, ctl->qth_max, ctl->Wlog))
371 return -EINVAL;
372
373 if (ctl->limit > CHOKE_MAX_QUEUE)
374 return -EINVAL;
375
376 mask = roundup_pow_of_two(ctl->limit + 1) - 1;
377 if (mask != q->tab_mask) {
378 struct sk_buff **ntab;
379
380 ntab = kvmalloc_array((mask + 1), sizeof(struct sk_buff *), GFP_KERNEL | __GFP_ZERO);
381 if (!ntab)
382 return -ENOMEM;
383
384 sch_tree_lock(sch);
385 old = q->tab;
386 if (old) {
387 unsigned int oqlen = sch->q.qlen, tail = 0;
388 unsigned dropped = 0;
389
390 while (q->head != q->tail) {
391 struct sk_buff *skb = q->tab[q->head];
392
393 q->head = (q->head + 1) & q->tab_mask;
394 if (!skb)
395 continue;
396 if (tail < mask) {
397 ntab[tail++] = skb;
398 continue;
399 }
400 dropped += qdisc_pkt_len(skb);
401 qdisc_qstats_backlog_dec(sch, skb);
402 --sch->q.qlen;
403 rtnl_qdisc_drop(skb, sch);
404 }
405 qdisc_tree_reduce_backlog(sch, oqlen - sch->q.qlen, dropped);
406 q->head = 0;
407 q->tail = tail;
408 }
409
410 q->tab_mask = mask;
411 q->tab = ntab;
412 } else
413 sch_tree_lock(sch);
414
415 q->flags = ctl->flags;
416 q->limit = ctl->limit;
417
418 red_set_parms(&q->parms, ctl->qth_min, ctl->qth_max, ctl->Wlog,
419 ctl->Plog, ctl->Scell_log,
420 nla_data(tb[TCA_CHOKE_STAB]),
421 max_P);
422 red_set_vars(&q->vars);
423
424 if (q->head == q->tail)
425 red_end_of_idle_period(&q->vars);
426
427 sch_tree_unlock(sch);
428 choke_free(old);
429 return 0;
430}
431
432static int choke_init(struct Qdisc *sch, struct nlattr *opt,
433 struct netlink_ext_ack *extack)
434{
435 return choke_change(sch, opt, extack);
436}
437
438static int choke_dump(struct Qdisc *sch, struct sk_buff *skb)
439{
440 struct choke_sched_data *q = qdisc_priv(sch);
441 struct nlattr *opts = NULL;
442 struct tc_red_qopt opt = {
443 .limit = q->limit,
444 .flags = q->flags,
445 .qth_min = q->parms.qth_min >> q->parms.Wlog,
446 .qth_max = q->parms.qth_max >> q->parms.Wlog,
447 .Wlog = q->parms.Wlog,
448 .Plog = q->parms.Plog,
449 .Scell_log = q->parms.Scell_log,
450 };
451
452 opts = nla_nest_start_noflag(skb, TCA_OPTIONS);
453 if (opts == NULL)
454 goto nla_put_failure;
455
456 if (nla_put(skb, TCA_CHOKE_PARMS, sizeof(opt), &opt) ||
457 nla_put_u32(skb, TCA_CHOKE_MAX_P, q->parms.max_P))
458 goto nla_put_failure;
459 return nla_nest_end(skb, opts);
460
461nla_put_failure:
462 nla_nest_cancel(skb, opts);
463 return -EMSGSIZE;
464}
465
466static int choke_dump_stats(struct Qdisc *sch, struct gnet_dump *d)
467{
468 struct choke_sched_data *q = qdisc_priv(sch);
469 struct tc_choke_xstats st = {
470 .early = q->stats.prob_drop + q->stats.forced_drop,
471 .marked = q->stats.prob_mark + q->stats.forced_mark,
472 .pdrop = q->stats.pdrop,
473 .other = q->stats.other,
474 .matched = q->stats.matched,
475 };
476
477 return gnet_stats_copy_app(d, &st, sizeof(st));
478}
479
480static void choke_destroy(struct Qdisc *sch)
481{
482 struct choke_sched_data *q = qdisc_priv(sch);
483
484 choke_free(q->tab);
485}
486
487static struct sk_buff *choke_peek_head(struct Qdisc *sch)
488{
489 struct choke_sched_data *q = qdisc_priv(sch);
490
491 return (q->head != q->tail) ? q->tab[q->head] : NULL;
492}
493
494static struct Qdisc_ops choke_qdisc_ops __read_mostly = {
495 .id = "choke",
496 .priv_size = sizeof(struct choke_sched_data),
497
498 .enqueue = choke_enqueue,
499 .dequeue = choke_dequeue,
500 .peek = choke_peek_head,
501 .init = choke_init,
502 .destroy = choke_destroy,
503 .reset = choke_reset,
504 .change = choke_change,
505 .dump = choke_dump,
506 .dump_stats = choke_dump_stats,
507 .owner = THIS_MODULE,
508};
509
510static int __init choke_module_init(void)
511{
512 return register_qdisc(&choke_qdisc_ops);
513}
514
515static void __exit choke_module_exit(void)
516{
517 unregister_qdisc(&choke_qdisc_ops);
518}
519
520module_init(choke_module_init)
521module_exit(choke_module_exit)
522
523MODULE_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/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
52struct 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 */
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 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
137struct choke_skb_cb {
138 u16 classid;
139 u8 keys_valid;
140 struct flow_keys_digest keys;
141};
142
143static 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
149static 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 */
159static 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 */
190static 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 */
210static 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
223static 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
289congestion_drop:
290 qdisc_drop(skb, sch, to_free);
291 return NET_XMIT_CN;
292}
293
294static 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
315static 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
335static 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
342static void choke_free(void *addr)
343{
344 kvfree(addr);
345}
346
347static 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
435static 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
441static 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
464nla_put_failure:
465 nla_nest_cancel(skb, opts);
466 return -EMSGSIZE;
467}
468
469static 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
483static void choke_destroy(struct Qdisc *sch)
484{
485 struct choke_sched_data *q = qdisc_priv(sch);
486
487 choke_free(q->tab);
488}
489
490static 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
497static 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
513static int __init choke_module_init(void)
514{
515 return register_qdisc(&choke_qdisc_ops);
516}
517
518static void __exit choke_module_exit(void)
519{
520 unregister_qdisc(&choke_qdisc_ops);
521}
522
523module_init(choke_module_init)
524module_exit(choke_module_exit)
525
526MODULE_LICENSE("GPL");