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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/reciprocal_div.h>
18#include <linux/vmalloc.h>
19#include <net/pkt_sched.h>
20#include <net/inet_ecn.h>
21#include <net/red.h>
22#include <linux/ip.h>
23#include <net/ip.h>
24#include <linux/ipv6.h>
25#include <net/ipv6.h>
26
27/*
28 CHOKe stateless AQM for fair bandwidth allocation
29 =================================================
30
31 CHOKe (CHOose and Keep for responsive flows, CHOose and Kill for
32 unresponsive flows) is a variant of RED that penalizes misbehaving flows but
33 maintains no flow state. The difference from RED is an additional step
34 during the enqueuing process. If average queue size is over the
35 low threshold (qmin), a packet is chosen at random from the queue.
36 If both the new and chosen packet are from the same flow, both
37 are dropped. Unlike RED, CHOKe is not really a "classful" qdisc because it
38 needs to access packets in queue randomly. It has a minimal class
39 interface to allow overriding the builtin flow classifier with
40 filters.
41
42 Source:
43 R. Pan, B. Prabhakar, and K. Psounis, "CHOKe, A Stateless
44 Active Queue Management Scheme for Approximating Fair Bandwidth Allocation",
45 IEEE INFOCOM, 2000.
46
47 A. Tang, J. Wang, S. Low, "Understanding CHOKe: Throughput and Spatial
48 Characteristics", IEEE/ACM Transactions on Networking, 2004
49
50 */
51
52/* Upper bound on size of sk_buff table (packets) */
53#define CHOKE_MAX_QUEUE (128*1024 - 1)
54
55struct choke_sched_data {
56/* Parameters */
57 u32 limit;
58 unsigned char flags;
59
60 struct red_parms parms;
61
62/* Variables */
63 struct tcf_proto *filter_list;
64 struct {
65 u32 prob_drop; /* Early probability drops */
66 u32 prob_mark; /* Early probability marks */
67 u32 forced_drop; /* Forced drops, qavg > max_thresh */
68 u32 forced_mark; /* Forced marks, qavg > max_thresh */
69 u32 pdrop; /* Drops due to queue limits */
70 u32 other; /* Drops due to drop() calls */
71 u32 matched; /* Drops to flow match */
72 } stats;
73
74 unsigned int head;
75 unsigned int tail;
76
77 unsigned int tab_mask; /* size - 1 */
78
79 struct sk_buff **tab;
80};
81
82/* deliver a random number between 0 and N - 1 */
83static u32 random_N(unsigned int N)
84{
85 return reciprocal_divide(random32(), N);
86}
87
88/* number of elements in queue including holes */
89static unsigned int choke_len(const struct choke_sched_data *q)
90{
91 return (q->tail - q->head) & q->tab_mask;
92}
93
94/* Is ECN parameter configured */
95static int use_ecn(const struct choke_sched_data *q)
96{
97 return q->flags & TC_RED_ECN;
98}
99
100/* Should packets over max just be dropped (versus marked) */
101static int use_harddrop(const struct choke_sched_data *q)
102{
103 return q->flags & TC_RED_HARDDROP;
104}
105
106/* Move head pointer forward to skip over holes */
107static void choke_zap_head_holes(struct choke_sched_data *q)
108{
109 do {
110 q->head = (q->head + 1) & q->tab_mask;
111 if (q->head == q->tail)
112 break;
113 } while (q->tab[q->head] == NULL);
114}
115
116/* Move tail pointer backwards to reuse holes */
117static void choke_zap_tail_holes(struct choke_sched_data *q)
118{
119 do {
120 q->tail = (q->tail - 1) & q->tab_mask;
121 if (q->head == q->tail)
122 break;
123 } while (q->tab[q->tail] == NULL);
124}
125
126/* Drop packet from queue array by creating a "hole" */
127static void choke_drop_by_idx(struct Qdisc *sch, unsigned int idx)
128{
129 struct choke_sched_data *q = qdisc_priv(sch);
130 struct sk_buff *skb = q->tab[idx];
131
132 q->tab[idx] = NULL;
133
134 if (idx == q->head)
135 choke_zap_head_holes(q);
136 if (idx == q->tail)
137 choke_zap_tail_holes(q);
138
139 sch->qstats.backlog -= qdisc_pkt_len(skb);
140 qdisc_drop(skb, sch);
141 qdisc_tree_decrease_qlen(sch, 1);
142 --sch->q.qlen;
143}
144
145/*
146 * Compare flow of two packets
147 * Returns true only if source and destination address and port match.
148 * false for special cases
149 */
150static bool choke_match_flow(struct sk_buff *skb1,
151 struct sk_buff *skb2)
152{
153 int off1, off2, poff;
154 const u32 *ports1, *ports2;
155 u8 ip_proto;
156 __u32 hash1;
157
158 if (skb1->protocol != skb2->protocol)
159 return false;
160
161 /* Use hash value as quick check
162 * Assumes that __skb_get_rxhash makes IP header and ports linear
163 */
164 hash1 = skb_get_rxhash(skb1);
165 if (!hash1 || hash1 != skb_get_rxhash(skb2))
166 return false;
167
168 /* Probably match, but be sure to avoid hash collisions */
169 off1 = skb_network_offset(skb1);
170 off2 = skb_network_offset(skb2);
171
172 switch (skb1->protocol) {
173 case __constant_htons(ETH_P_IP): {
174 const struct iphdr *ip1, *ip2;
175
176 ip1 = (const struct iphdr *) (skb1->data + off1);
177 ip2 = (const struct iphdr *) (skb2->data + off2);
178
179 ip_proto = ip1->protocol;
180 if (ip_proto != ip2->protocol ||
181 ip1->saddr != ip2->saddr || ip1->daddr != ip2->daddr)
182 return false;
183
184 if (ip_is_fragment(ip1) | ip_is_fragment(ip2))
185 ip_proto = 0;
186 off1 += ip1->ihl * 4;
187 off2 += ip2->ihl * 4;
188 break;
189 }
190
191 case __constant_htons(ETH_P_IPV6): {
192 const struct ipv6hdr *ip1, *ip2;
193
194 ip1 = (const struct ipv6hdr *) (skb1->data + off1);
195 ip2 = (const struct ipv6hdr *) (skb2->data + off2);
196
197 ip_proto = ip1->nexthdr;
198 if (ip_proto != ip2->nexthdr ||
199 ipv6_addr_cmp(&ip1->saddr, &ip2->saddr) ||
200 ipv6_addr_cmp(&ip1->daddr, &ip2->daddr))
201 return false;
202 off1 += 40;
203 off2 += 40;
204 }
205
206 default: /* Maybe compare MAC header here? */
207 return false;
208 }
209
210 poff = proto_ports_offset(ip_proto);
211 if (poff < 0)
212 return true;
213
214 off1 += poff;
215 off2 += poff;
216
217 ports1 = (__force u32 *)(skb1->data + off1);
218 ports2 = (__force u32 *)(skb2->data + off2);
219 return *ports1 == *ports2;
220}
221
222struct choke_skb_cb {
223 u16 classid;
224};
225
226static inline struct choke_skb_cb *choke_skb_cb(const struct sk_buff *skb)
227{
228 BUILD_BUG_ON(sizeof(skb->cb) <
229 sizeof(struct qdisc_skb_cb) + sizeof(struct choke_skb_cb));
230 return (struct choke_skb_cb *)qdisc_skb_cb(skb)->data;
231}
232
233static inline void choke_set_classid(struct sk_buff *skb, u16 classid)
234{
235 choke_skb_cb(skb)->classid = classid;
236}
237
238static u16 choke_get_classid(const struct sk_buff *skb)
239{
240 return choke_skb_cb(skb)->classid;
241}
242
243/*
244 * Classify flow using either:
245 * 1. pre-existing classification result in skb
246 * 2. fast internal classification
247 * 3. use TC filter based classification
248 */
249static bool choke_classify(struct sk_buff *skb,
250 struct Qdisc *sch, int *qerr)
251
252{
253 struct choke_sched_data *q = qdisc_priv(sch);
254 struct tcf_result res;
255 int result;
256
257 result = tc_classify(skb, q->filter_list, &res);
258 if (result >= 0) {
259#ifdef CONFIG_NET_CLS_ACT
260 switch (result) {
261 case TC_ACT_STOLEN:
262 case TC_ACT_QUEUED:
263 *qerr = NET_XMIT_SUCCESS | __NET_XMIT_STOLEN;
264 case TC_ACT_SHOT:
265 return false;
266 }
267#endif
268 choke_set_classid(skb, TC_H_MIN(res.classid));
269 return true;
270 }
271
272 return false;
273}
274
275/*
276 * Select a packet at random from queue
277 * HACK: since queue can have holes from previous deletion; retry several
278 * times to find a random skb but then just give up and return the head
279 * Will return NULL if queue is empty (q->head == q->tail)
280 */
281static struct sk_buff *choke_peek_random(const struct choke_sched_data *q,
282 unsigned int *pidx)
283{
284 struct sk_buff *skb;
285 int retrys = 3;
286
287 do {
288 *pidx = (q->head + random_N(choke_len(q))) & q->tab_mask;
289 skb = q->tab[*pidx];
290 if (skb)
291 return skb;
292 } while (--retrys > 0);
293
294 return q->tab[*pidx = q->head];
295}
296
297/*
298 * Compare new packet with random packet in queue
299 * returns true if matched and sets *pidx
300 */
301static bool choke_match_random(const struct choke_sched_data *q,
302 struct sk_buff *nskb,
303 unsigned int *pidx)
304{
305 struct sk_buff *oskb;
306
307 if (q->head == q->tail)
308 return false;
309
310 oskb = choke_peek_random(q, pidx);
311 if (q->filter_list)
312 return choke_get_classid(nskb) == choke_get_classid(oskb);
313
314 return choke_match_flow(oskb, nskb);
315}
316
317static int choke_enqueue(struct sk_buff *skb, struct Qdisc *sch)
318{
319 struct choke_sched_data *q = qdisc_priv(sch);
320 struct red_parms *p = &q->parms;
321 int ret = NET_XMIT_SUCCESS | __NET_XMIT_BYPASS;
322
323 if (q->filter_list) {
324 /* If using external classifiers, get result and record it. */
325 if (!choke_classify(skb, sch, &ret))
326 goto other_drop; /* Packet was eaten by filter */
327 }
328
329 /* Compute average queue usage (see RED) */
330 p->qavg = red_calc_qavg(p, sch->q.qlen);
331 if (red_is_idling(p))
332 red_end_of_idle_period(p);
333
334 /* Is queue small? */
335 if (p->qavg <= p->qth_min)
336 p->qcount = -1;
337 else {
338 unsigned int idx;
339
340 /* Draw a packet at random from queue and compare flow */
341 if (choke_match_random(q, skb, &idx)) {
342 q->stats.matched++;
343 choke_drop_by_idx(sch, idx);
344 goto congestion_drop;
345 }
346
347 /* Queue is large, always mark/drop */
348 if (p->qavg > p->qth_max) {
349 p->qcount = -1;
350
351 sch->qstats.overlimits++;
352 if (use_harddrop(q) || !use_ecn(q) ||
353 !INET_ECN_set_ce(skb)) {
354 q->stats.forced_drop++;
355 goto congestion_drop;
356 }
357
358 q->stats.forced_mark++;
359 } else if (++p->qcount) {
360 if (red_mark_probability(p, p->qavg)) {
361 p->qcount = 0;
362 p->qR = red_random(p);
363
364 sch->qstats.overlimits++;
365 if (!use_ecn(q) || !INET_ECN_set_ce(skb)) {
366 q->stats.prob_drop++;
367 goto congestion_drop;
368 }
369
370 q->stats.prob_mark++;
371 }
372 } else
373 p->qR = red_random(p);
374 }
375
376 /* Admit new packet */
377 if (sch->q.qlen < q->limit) {
378 q->tab[q->tail] = skb;
379 q->tail = (q->tail + 1) & q->tab_mask;
380 ++sch->q.qlen;
381 sch->qstats.backlog += qdisc_pkt_len(skb);
382 return NET_XMIT_SUCCESS;
383 }
384
385 q->stats.pdrop++;
386 sch->qstats.drops++;
387 kfree_skb(skb);
388 return NET_XMIT_DROP;
389
390 congestion_drop:
391 qdisc_drop(skb, sch);
392 return NET_XMIT_CN;
393
394 other_drop:
395 if (ret & __NET_XMIT_BYPASS)
396 sch->qstats.drops++;
397 kfree_skb(skb);
398 return ret;
399}
400
401static struct sk_buff *choke_dequeue(struct Qdisc *sch)
402{
403 struct choke_sched_data *q = qdisc_priv(sch);
404 struct sk_buff *skb;
405
406 if (q->head == q->tail) {
407 if (!red_is_idling(&q->parms))
408 red_start_of_idle_period(&q->parms);
409 return NULL;
410 }
411
412 skb = q->tab[q->head];
413 q->tab[q->head] = NULL;
414 choke_zap_head_holes(q);
415 --sch->q.qlen;
416 sch->qstats.backlog -= qdisc_pkt_len(skb);
417 qdisc_bstats_update(sch, skb);
418
419 return skb;
420}
421
422static unsigned int choke_drop(struct Qdisc *sch)
423{
424 struct choke_sched_data *q = qdisc_priv(sch);
425 unsigned int len;
426
427 len = qdisc_queue_drop(sch);
428 if (len > 0)
429 q->stats.other++;
430 else {
431 if (!red_is_idling(&q->parms))
432 red_start_of_idle_period(&q->parms);
433 }
434
435 return len;
436}
437
438static void choke_reset(struct Qdisc *sch)
439{
440 struct choke_sched_data *q = qdisc_priv(sch);
441
442 red_restart(&q->parms);
443}
444
445static const struct nla_policy choke_policy[TCA_CHOKE_MAX + 1] = {
446 [TCA_CHOKE_PARMS] = { .len = sizeof(struct tc_red_qopt) },
447 [TCA_CHOKE_STAB] = { .len = RED_STAB_SIZE },
448};
449
450
451static void choke_free(void *addr)
452{
453 if (addr) {
454 if (is_vmalloc_addr(addr))
455 vfree(addr);
456 else
457 kfree(addr);
458 }
459}
460
461static int choke_change(struct Qdisc *sch, struct nlattr *opt)
462{
463 struct choke_sched_data *q = qdisc_priv(sch);
464 struct nlattr *tb[TCA_CHOKE_MAX + 1];
465 const struct tc_red_qopt *ctl;
466 int err;
467 struct sk_buff **old = NULL;
468 unsigned int mask;
469
470 if (opt == NULL)
471 return -EINVAL;
472
473 err = nla_parse_nested(tb, TCA_CHOKE_MAX, opt, choke_policy);
474 if (err < 0)
475 return err;
476
477 if (tb[TCA_CHOKE_PARMS] == NULL ||
478 tb[TCA_CHOKE_STAB] == NULL)
479 return -EINVAL;
480
481 ctl = nla_data(tb[TCA_CHOKE_PARMS]);
482
483 if (ctl->limit > CHOKE_MAX_QUEUE)
484 return -EINVAL;
485
486 mask = roundup_pow_of_two(ctl->limit + 1) - 1;
487 if (mask != q->tab_mask) {
488 struct sk_buff **ntab;
489
490 ntab = kcalloc(mask + 1, sizeof(struct sk_buff *), GFP_KERNEL);
491 if (!ntab)
492 ntab = vzalloc((mask + 1) * sizeof(struct sk_buff *));
493 if (!ntab)
494 return -ENOMEM;
495
496 sch_tree_lock(sch);
497 old = q->tab;
498 if (old) {
499 unsigned int oqlen = sch->q.qlen, tail = 0;
500
501 while (q->head != q->tail) {
502 struct sk_buff *skb = q->tab[q->head];
503
504 q->head = (q->head + 1) & q->tab_mask;
505 if (!skb)
506 continue;
507 if (tail < mask) {
508 ntab[tail++] = skb;
509 continue;
510 }
511 sch->qstats.backlog -= qdisc_pkt_len(skb);
512 --sch->q.qlen;
513 qdisc_drop(skb, sch);
514 }
515 qdisc_tree_decrease_qlen(sch, oqlen - sch->q.qlen);
516 q->head = 0;
517 q->tail = tail;
518 }
519
520 q->tab_mask = mask;
521 q->tab = ntab;
522 } else
523 sch_tree_lock(sch);
524
525 q->flags = ctl->flags;
526 q->limit = ctl->limit;
527
528 red_set_parms(&q->parms, ctl->qth_min, ctl->qth_max, ctl->Wlog,
529 ctl->Plog, ctl->Scell_log,
530 nla_data(tb[TCA_CHOKE_STAB]));
531
532 if (q->head == q->tail)
533 red_end_of_idle_period(&q->parms);
534
535 sch_tree_unlock(sch);
536 choke_free(old);
537 return 0;
538}
539
540static int choke_init(struct Qdisc *sch, struct nlattr *opt)
541{
542 return choke_change(sch, opt);
543}
544
545static int choke_dump(struct Qdisc *sch, struct sk_buff *skb)
546{
547 struct choke_sched_data *q = qdisc_priv(sch);
548 struct nlattr *opts = NULL;
549 struct tc_red_qopt opt = {
550 .limit = q->limit,
551 .flags = q->flags,
552 .qth_min = q->parms.qth_min >> q->parms.Wlog,
553 .qth_max = q->parms.qth_max >> q->parms.Wlog,
554 .Wlog = q->parms.Wlog,
555 .Plog = q->parms.Plog,
556 .Scell_log = q->parms.Scell_log,
557 };
558
559 opts = nla_nest_start(skb, TCA_OPTIONS);
560 if (opts == NULL)
561 goto nla_put_failure;
562
563 NLA_PUT(skb, TCA_CHOKE_PARMS, sizeof(opt), &opt);
564 return nla_nest_end(skb, opts);
565
566nla_put_failure:
567 nla_nest_cancel(skb, opts);
568 return -EMSGSIZE;
569}
570
571static int choke_dump_stats(struct Qdisc *sch, struct gnet_dump *d)
572{
573 struct choke_sched_data *q = qdisc_priv(sch);
574 struct tc_choke_xstats st = {
575 .early = q->stats.prob_drop + q->stats.forced_drop,
576 .marked = q->stats.prob_mark + q->stats.forced_mark,
577 .pdrop = q->stats.pdrop,
578 .other = q->stats.other,
579 .matched = q->stats.matched,
580 };
581
582 return gnet_stats_copy_app(d, &st, sizeof(st));
583}
584
585static void choke_destroy(struct Qdisc *sch)
586{
587 struct choke_sched_data *q = qdisc_priv(sch);
588
589 tcf_destroy_chain(&q->filter_list);
590 choke_free(q->tab);
591}
592
593static struct Qdisc *choke_leaf(struct Qdisc *sch, unsigned long arg)
594{
595 return NULL;
596}
597
598static unsigned long choke_get(struct Qdisc *sch, u32 classid)
599{
600 return 0;
601}
602
603static void choke_put(struct Qdisc *q, unsigned long cl)
604{
605}
606
607static unsigned long choke_bind(struct Qdisc *sch, unsigned long parent,
608 u32 classid)
609{
610 return 0;
611}
612
613static struct tcf_proto **choke_find_tcf(struct Qdisc *sch, unsigned long cl)
614{
615 struct choke_sched_data *q = qdisc_priv(sch);
616
617 if (cl)
618 return NULL;
619 return &q->filter_list;
620}
621
622static int choke_dump_class(struct Qdisc *sch, unsigned long cl,
623 struct sk_buff *skb, struct tcmsg *tcm)
624{
625 tcm->tcm_handle |= TC_H_MIN(cl);
626 return 0;
627}
628
629static void choke_walk(struct Qdisc *sch, struct qdisc_walker *arg)
630{
631 if (!arg->stop) {
632 if (arg->fn(sch, 1, arg) < 0) {
633 arg->stop = 1;
634 return;
635 }
636 arg->count++;
637 }
638}
639
640static const struct Qdisc_class_ops choke_class_ops = {
641 .leaf = choke_leaf,
642 .get = choke_get,
643 .put = choke_put,
644 .tcf_chain = choke_find_tcf,
645 .bind_tcf = choke_bind,
646 .unbind_tcf = choke_put,
647 .dump = choke_dump_class,
648 .walk = choke_walk,
649};
650
651static struct sk_buff *choke_peek_head(struct Qdisc *sch)
652{
653 struct choke_sched_data *q = qdisc_priv(sch);
654
655 return (q->head != q->tail) ? q->tab[q->head] : NULL;
656}
657
658static struct Qdisc_ops choke_qdisc_ops __read_mostly = {
659 .id = "choke",
660 .priv_size = sizeof(struct choke_sched_data),
661
662 .enqueue = choke_enqueue,
663 .dequeue = choke_dequeue,
664 .peek = choke_peek_head,
665 .drop = choke_drop,
666 .init = choke_init,
667 .destroy = choke_destroy,
668 .reset = choke_reset,
669 .change = choke_change,
670 .dump = choke_dump,
671 .dump_stats = choke_dump_stats,
672 .owner = THIS_MODULE,
673};
674
675static int __init choke_module_init(void)
676{
677 return register_qdisc(&choke_qdisc_ops);
678}
679
680static void __exit choke_module_exit(void)
681{
682 unregister_qdisc(&choke_qdisc_ops);
683}
684
685module_init(choke_module_init)
686module_exit(choke_module_exit)
687
688MODULE_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");