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