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1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * net/sched/sch_sfq.c Stochastic Fairness Queueing discipline.
4 *
5 * Authors: Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
6 */
7
8#include <linux/module.h>
9#include <linux/types.h>
10#include <linux/kernel.h>
11#include <linux/jiffies.h>
12#include <linux/string.h>
13#include <linux/in.h>
14#include <linux/errno.h>
15#include <linux/init.h>
16#include <linux/skbuff.h>
17#include <linux/siphash.h>
18#include <linux/slab.h>
19#include <linux/vmalloc.h>
20#include <net/netlink.h>
21#include <net/pkt_sched.h>
22#include <net/pkt_cls.h>
23#include <net/red.h>
24
25
26/* Stochastic Fairness Queuing algorithm.
27 =======================================
28
29 Source:
30 Paul E. McKenney "Stochastic Fairness Queuing",
31 IEEE INFOCOMM'90 Proceedings, San Francisco, 1990.
32
33 Paul E. McKenney "Stochastic Fairness Queuing",
34 "Interworking: Research and Experience", v.2, 1991, p.113-131.
35
36
37 See also:
38 M. Shreedhar and George Varghese "Efficient Fair
39 Queuing using Deficit Round Robin", Proc. SIGCOMM 95.
40
41
42 This is not the thing that is usually called (W)FQ nowadays.
43 It does not use any timestamp mechanism, but instead
44 processes queues in round-robin order.
45
46 ADVANTAGE:
47
48 - It is very cheap. Both CPU and memory requirements are minimal.
49
50 DRAWBACKS:
51
52 - "Stochastic" -> It is not 100% fair.
53 When hash collisions occur, several flows are considered as one.
54
55 - "Round-robin" -> It introduces larger delays than virtual clock
56 based schemes, and should not be used for isolating interactive
57 traffic from non-interactive. It means, that this scheduler
58 should be used as leaf of CBQ or P3, which put interactive traffic
59 to higher priority band.
60
61 We still need true WFQ for top level CSZ, but using WFQ
62 for the best effort traffic is absolutely pointless:
63 SFQ is superior for this purpose.
64
65 IMPLEMENTATION:
66 This implementation limits :
67 - maximal queue length per flow to 127 packets.
68 - max mtu to 2^18-1;
69 - max 65408 flows,
70 - number of hash buckets to 65536.
71
72 It is easy to increase these values, but not in flight. */
73
74#define SFQ_MAX_DEPTH 127 /* max number of packets per flow */
75#define SFQ_DEFAULT_FLOWS 128
76#define SFQ_MAX_FLOWS (0x10000 - SFQ_MAX_DEPTH - 1) /* max number of flows */
77#define SFQ_EMPTY_SLOT 0xffff
78#define SFQ_DEFAULT_HASH_DIVISOR 1024
79
80/* This type should contain at least SFQ_MAX_DEPTH + 1 + SFQ_MAX_FLOWS values */
81typedef u16 sfq_index;
82
83/*
84 * We dont use pointers to save space.
85 * Small indexes [0 ... SFQ_MAX_FLOWS - 1] are 'pointers' to slots[] array
86 * while following values [SFQ_MAX_FLOWS ... SFQ_MAX_FLOWS + SFQ_MAX_DEPTH]
87 * are 'pointers' to dep[] array
88 */
89struct sfq_head {
90 sfq_index next;
91 sfq_index prev;
92};
93
94struct sfq_slot {
95 struct sk_buff *skblist_next;
96 struct sk_buff *skblist_prev;
97 sfq_index qlen; /* number of skbs in skblist */
98 sfq_index next; /* next slot in sfq RR chain */
99 struct sfq_head dep; /* anchor in dep[] chains */
100 unsigned short hash; /* hash value (index in ht[]) */
101 int allot; /* credit for this slot */
102
103 unsigned int backlog;
104 struct red_vars vars;
105};
106
107struct sfq_sched_data {
108/* frequently used fields */
109 int limit; /* limit of total number of packets in this qdisc */
110 unsigned int divisor; /* number of slots in hash table */
111 u8 headdrop;
112 u8 maxdepth; /* limit of packets per flow */
113
114 siphash_key_t perturbation;
115 u8 cur_depth; /* depth of longest slot */
116 u8 flags;
117 struct tcf_proto __rcu *filter_list;
118 struct tcf_block *block;
119 sfq_index *ht; /* Hash table ('divisor' slots) */
120 struct sfq_slot *slots; /* Flows table ('maxflows' entries) */
121
122 struct red_parms *red_parms;
123 struct tc_sfqred_stats stats;
124 struct sfq_slot *tail; /* current slot in round */
125
126 struct sfq_head dep[SFQ_MAX_DEPTH + 1];
127 /* Linked lists of slots, indexed by depth
128 * dep[0] : list of unused flows
129 * dep[1] : list of flows with 1 packet
130 * dep[X] : list of flows with X packets
131 */
132
133 unsigned int maxflows; /* number of flows in flows array */
134 int perturb_period;
135 unsigned int quantum; /* Allotment per round: MUST BE >= MTU */
136 struct timer_list perturb_timer;
137 struct Qdisc *sch;
138};
139
140/*
141 * sfq_head are either in a sfq_slot or in dep[] array
142 */
143static inline struct sfq_head *sfq_dep_head(struct sfq_sched_data *q, sfq_index val)
144{
145 if (val < SFQ_MAX_FLOWS)
146 return &q->slots[val].dep;
147 return &q->dep[val - SFQ_MAX_FLOWS];
148}
149
150static unsigned int sfq_hash(const struct sfq_sched_data *q,
151 const struct sk_buff *skb)
152{
153 return skb_get_hash_perturb(skb, &q->perturbation) & (q->divisor - 1);
154}
155
156static unsigned int sfq_classify(struct sk_buff *skb, struct Qdisc *sch,
157 int *qerr)
158{
159 struct sfq_sched_data *q = qdisc_priv(sch);
160 struct tcf_result res;
161 struct tcf_proto *fl;
162 int result;
163
164 if (TC_H_MAJ(skb->priority) == sch->handle &&
165 TC_H_MIN(skb->priority) > 0 &&
166 TC_H_MIN(skb->priority) <= q->divisor)
167 return TC_H_MIN(skb->priority);
168
169 fl = rcu_dereference_bh(q->filter_list);
170 if (!fl)
171 return sfq_hash(q, skb) + 1;
172
173 *qerr = NET_XMIT_SUCCESS | __NET_XMIT_BYPASS;
174 result = tcf_classify(skb, NULL, fl, &res, false);
175 if (result >= 0) {
176#ifdef CONFIG_NET_CLS_ACT
177 switch (result) {
178 case TC_ACT_STOLEN:
179 case TC_ACT_QUEUED:
180 case TC_ACT_TRAP:
181 *qerr = NET_XMIT_SUCCESS | __NET_XMIT_STOLEN;
182 fallthrough;
183 case TC_ACT_SHOT:
184 return 0;
185 }
186#endif
187 if (TC_H_MIN(res.classid) <= q->divisor)
188 return TC_H_MIN(res.classid);
189 }
190 return 0;
191}
192
193/*
194 * x : slot number [0 .. SFQ_MAX_FLOWS - 1]
195 */
196static inline void sfq_link(struct sfq_sched_data *q, sfq_index x)
197{
198 sfq_index p, n;
199 struct sfq_slot *slot = &q->slots[x];
200 int qlen = slot->qlen;
201
202 p = qlen + SFQ_MAX_FLOWS;
203 n = q->dep[qlen].next;
204
205 slot->dep.next = n;
206 slot->dep.prev = p;
207
208 q->dep[qlen].next = x; /* sfq_dep_head(q, p)->next = x */
209 sfq_dep_head(q, n)->prev = x;
210}
211
212#define sfq_unlink(q, x, n, p) \
213 do { \
214 n = q->slots[x].dep.next; \
215 p = q->slots[x].dep.prev; \
216 sfq_dep_head(q, p)->next = n; \
217 sfq_dep_head(q, n)->prev = p; \
218 } while (0)
219
220
221static inline void sfq_dec(struct sfq_sched_data *q, sfq_index x)
222{
223 sfq_index p, n;
224 int d;
225
226 sfq_unlink(q, x, n, p);
227
228 d = q->slots[x].qlen--;
229 if (n == p && q->cur_depth == d)
230 q->cur_depth--;
231 sfq_link(q, x);
232}
233
234static inline void sfq_inc(struct sfq_sched_data *q, sfq_index x)
235{
236 sfq_index p, n;
237 int d;
238
239 sfq_unlink(q, x, n, p);
240
241 d = ++q->slots[x].qlen;
242 if (q->cur_depth < d)
243 q->cur_depth = d;
244 sfq_link(q, x);
245}
246
247/* helper functions : might be changed when/if skb use a standard list_head */
248
249/* remove one skb from tail of slot queue */
250static inline struct sk_buff *slot_dequeue_tail(struct sfq_slot *slot)
251{
252 struct sk_buff *skb = slot->skblist_prev;
253
254 slot->skblist_prev = skb->prev;
255 skb->prev->next = (struct sk_buff *)slot;
256 skb->next = skb->prev = NULL;
257 return skb;
258}
259
260/* remove one skb from head of slot queue */
261static inline struct sk_buff *slot_dequeue_head(struct sfq_slot *slot)
262{
263 struct sk_buff *skb = slot->skblist_next;
264
265 slot->skblist_next = skb->next;
266 skb->next->prev = (struct sk_buff *)slot;
267 skb->next = skb->prev = NULL;
268 return skb;
269}
270
271static inline void slot_queue_init(struct sfq_slot *slot)
272{
273 memset(slot, 0, sizeof(*slot));
274 slot->skblist_prev = slot->skblist_next = (struct sk_buff *)slot;
275}
276
277/* add skb to slot queue (tail add) */
278static inline void slot_queue_add(struct sfq_slot *slot, struct sk_buff *skb)
279{
280 skb->prev = slot->skblist_prev;
281 skb->next = (struct sk_buff *)slot;
282 slot->skblist_prev->next = skb;
283 slot->skblist_prev = skb;
284}
285
286static unsigned int sfq_drop(struct Qdisc *sch, struct sk_buff **to_free)
287{
288 struct sfq_sched_data *q = qdisc_priv(sch);
289 sfq_index x, d = q->cur_depth;
290 struct sk_buff *skb;
291 unsigned int len;
292 struct sfq_slot *slot;
293
294 /* Queue is full! Find the longest slot and drop tail packet from it */
295 if (d > 1) {
296 x = q->dep[d].next;
297 slot = &q->slots[x];
298drop:
299 skb = q->headdrop ? slot_dequeue_head(slot) : slot_dequeue_tail(slot);
300 len = qdisc_pkt_len(skb);
301 slot->backlog -= len;
302 sfq_dec(q, x);
303 sch->q.qlen--;
304 qdisc_qstats_backlog_dec(sch, skb);
305 qdisc_drop(skb, sch, to_free);
306 return len;
307 }
308
309 if (d == 1) {
310 /* It is difficult to believe, but ALL THE SLOTS HAVE LENGTH 1. */
311 x = q->tail->next;
312 slot = &q->slots[x];
313 q->tail->next = slot->next;
314 q->ht[slot->hash] = SFQ_EMPTY_SLOT;
315 goto drop;
316 }
317
318 return 0;
319}
320
321/* Is ECN parameter configured */
322static int sfq_prob_mark(const struct sfq_sched_data *q)
323{
324 return q->flags & TC_RED_ECN;
325}
326
327/* Should packets over max threshold just be marked */
328static int sfq_hard_mark(const struct sfq_sched_data *q)
329{
330 return (q->flags & (TC_RED_ECN | TC_RED_HARDDROP)) == TC_RED_ECN;
331}
332
333static int sfq_headdrop(const struct sfq_sched_data *q)
334{
335 return q->headdrop;
336}
337
338static int
339sfq_enqueue(struct sk_buff *skb, struct Qdisc *sch, struct sk_buff **to_free)
340{
341 struct sfq_sched_data *q = qdisc_priv(sch);
342 unsigned int hash, dropped;
343 sfq_index x, qlen;
344 struct sfq_slot *slot;
345 int ret;
346 struct sk_buff *head;
347 int delta;
348
349 hash = sfq_classify(skb, sch, &ret);
350 if (hash == 0) {
351 if (ret & __NET_XMIT_BYPASS)
352 qdisc_qstats_drop(sch);
353 __qdisc_drop(skb, to_free);
354 return ret;
355 }
356 hash--;
357
358 x = q->ht[hash];
359 slot = &q->slots[x];
360 if (x == SFQ_EMPTY_SLOT) {
361 x = q->dep[0].next; /* get a free slot */
362 if (x >= SFQ_MAX_FLOWS)
363 return qdisc_drop(skb, sch, to_free);
364 q->ht[hash] = x;
365 slot = &q->slots[x];
366 slot->hash = hash;
367 slot->backlog = 0; /* should already be 0 anyway... */
368 red_set_vars(&slot->vars);
369 goto enqueue;
370 }
371 if (q->red_parms) {
372 slot->vars.qavg = red_calc_qavg_no_idle_time(q->red_parms,
373 &slot->vars,
374 slot->backlog);
375 switch (red_action(q->red_parms,
376 &slot->vars,
377 slot->vars.qavg)) {
378 case RED_DONT_MARK:
379 break;
380
381 case RED_PROB_MARK:
382 qdisc_qstats_overlimit(sch);
383 if (sfq_prob_mark(q)) {
384 /* We know we have at least one packet in queue */
385 if (sfq_headdrop(q) &&
386 INET_ECN_set_ce(slot->skblist_next)) {
387 q->stats.prob_mark_head++;
388 break;
389 }
390 if (INET_ECN_set_ce(skb)) {
391 q->stats.prob_mark++;
392 break;
393 }
394 }
395 q->stats.prob_drop++;
396 goto congestion_drop;
397
398 case RED_HARD_MARK:
399 qdisc_qstats_overlimit(sch);
400 if (sfq_hard_mark(q)) {
401 /* We know we have at least one packet in queue */
402 if (sfq_headdrop(q) &&
403 INET_ECN_set_ce(slot->skblist_next)) {
404 q->stats.forced_mark_head++;
405 break;
406 }
407 if (INET_ECN_set_ce(skb)) {
408 q->stats.forced_mark++;
409 break;
410 }
411 }
412 q->stats.forced_drop++;
413 goto congestion_drop;
414 }
415 }
416
417 if (slot->qlen >= q->maxdepth) {
418congestion_drop:
419 if (!sfq_headdrop(q))
420 return qdisc_drop(skb, sch, to_free);
421
422 /* We know we have at least one packet in queue */
423 head = slot_dequeue_head(slot);
424 delta = qdisc_pkt_len(head) - qdisc_pkt_len(skb);
425 sch->qstats.backlog -= delta;
426 slot->backlog -= delta;
427 qdisc_drop(head, sch, to_free);
428
429 slot_queue_add(slot, skb);
430 qdisc_tree_reduce_backlog(sch, 0, delta);
431 return NET_XMIT_CN;
432 }
433
434enqueue:
435 qdisc_qstats_backlog_inc(sch, skb);
436 slot->backlog += qdisc_pkt_len(skb);
437 slot_queue_add(slot, skb);
438 sfq_inc(q, x);
439 if (slot->qlen == 1) { /* The flow is new */
440 if (q->tail == NULL) { /* It is the first flow */
441 slot->next = x;
442 } else {
443 slot->next = q->tail->next;
444 q->tail->next = x;
445 }
446 /* We put this flow at the end of our flow list.
447 * This might sound unfair for a new flow to wait after old ones,
448 * but we could endup servicing new flows only, and freeze old ones.
449 */
450 q->tail = slot;
451 /* We could use a bigger initial quantum for new flows */
452 slot->allot = q->quantum;
453 }
454 if (++sch->q.qlen <= q->limit)
455 return NET_XMIT_SUCCESS;
456
457 qlen = slot->qlen;
458 dropped = sfq_drop(sch, to_free);
459 /* Return Congestion Notification only if we dropped a packet
460 * from this flow.
461 */
462 if (qlen != slot->qlen) {
463 qdisc_tree_reduce_backlog(sch, 0, dropped - qdisc_pkt_len(skb));
464 return NET_XMIT_CN;
465 }
466
467 /* As we dropped a packet, better let upper stack know this */
468 qdisc_tree_reduce_backlog(sch, 1, dropped);
469 return NET_XMIT_SUCCESS;
470}
471
472static struct sk_buff *
473sfq_dequeue(struct Qdisc *sch)
474{
475 struct sfq_sched_data *q = qdisc_priv(sch);
476 struct sk_buff *skb;
477 sfq_index a, next_a;
478 struct sfq_slot *slot;
479
480 /* No active slots */
481 if (q->tail == NULL)
482 return NULL;
483
484next_slot:
485 a = q->tail->next;
486 slot = &q->slots[a];
487 if (slot->allot <= 0) {
488 q->tail = slot;
489 slot->allot += q->quantum;
490 goto next_slot;
491 }
492 skb = slot_dequeue_head(slot);
493 sfq_dec(q, a);
494 qdisc_bstats_update(sch, skb);
495 sch->q.qlen--;
496 qdisc_qstats_backlog_dec(sch, skb);
497 slot->backlog -= qdisc_pkt_len(skb);
498 /* Is the slot empty? */
499 if (slot->qlen == 0) {
500 q->ht[slot->hash] = SFQ_EMPTY_SLOT;
501 next_a = slot->next;
502 if (a == next_a) {
503 q->tail = NULL; /* no more active slots */
504 return skb;
505 }
506 q->tail->next = next_a;
507 } else {
508 slot->allot -= qdisc_pkt_len(skb);
509 }
510 return skb;
511}
512
513static void
514sfq_reset(struct Qdisc *sch)
515{
516 struct sk_buff *skb;
517
518 while ((skb = sfq_dequeue(sch)) != NULL)
519 rtnl_kfree_skbs(skb, skb);
520}
521
522/*
523 * When q->perturbation is changed, we rehash all queued skbs
524 * to avoid OOO (Out Of Order) effects.
525 * We dont use sfq_dequeue()/sfq_enqueue() because we dont want to change
526 * counters.
527 */
528static void sfq_rehash(struct Qdisc *sch)
529{
530 struct sfq_sched_data *q = qdisc_priv(sch);
531 struct sk_buff *skb;
532 int i;
533 struct sfq_slot *slot;
534 struct sk_buff_head list;
535 int dropped = 0;
536 unsigned int drop_len = 0;
537
538 __skb_queue_head_init(&list);
539
540 for (i = 0; i < q->maxflows; i++) {
541 slot = &q->slots[i];
542 if (!slot->qlen)
543 continue;
544 while (slot->qlen) {
545 skb = slot_dequeue_head(slot);
546 sfq_dec(q, i);
547 __skb_queue_tail(&list, skb);
548 }
549 slot->backlog = 0;
550 red_set_vars(&slot->vars);
551 q->ht[slot->hash] = SFQ_EMPTY_SLOT;
552 }
553 q->tail = NULL;
554
555 while ((skb = __skb_dequeue(&list)) != NULL) {
556 unsigned int hash = sfq_hash(q, skb);
557 sfq_index x = q->ht[hash];
558
559 slot = &q->slots[x];
560 if (x == SFQ_EMPTY_SLOT) {
561 x = q->dep[0].next; /* get a free slot */
562 if (x >= SFQ_MAX_FLOWS) {
563drop:
564 qdisc_qstats_backlog_dec(sch, skb);
565 drop_len += qdisc_pkt_len(skb);
566 kfree_skb(skb);
567 dropped++;
568 continue;
569 }
570 q->ht[hash] = x;
571 slot = &q->slots[x];
572 slot->hash = hash;
573 }
574 if (slot->qlen >= q->maxdepth)
575 goto drop;
576 slot_queue_add(slot, skb);
577 if (q->red_parms)
578 slot->vars.qavg = red_calc_qavg(q->red_parms,
579 &slot->vars,
580 slot->backlog);
581 slot->backlog += qdisc_pkt_len(skb);
582 sfq_inc(q, x);
583 if (slot->qlen == 1) { /* The flow is new */
584 if (q->tail == NULL) { /* It is the first flow */
585 slot->next = x;
586 } else {
587 slot->next = q->tail->next;
588 q->tail->next = x;
589 }
590 q->tail = slot;
591 slot->allot = q->quantum;
592 }
593 }
594 sch->q.qlen -= dropped;
595 qdisc_tree_reduce_backlog(sch, dropped, drop_len);
596}
597
598static void sfq_perturbation(struct timer_list *t)
599{
600 struct sfq_sched_data *q = from_timer(q, t, perturb_timer);
601 struct Qdisc *sch = q->sch;
602 spinlock_t *root_lock;
603 siphash_key_t nkey;
604 int period;
605
606 get_random_bytes(&nkey, sizeof(nkey));
607 rcu_read_lock();
608 root_lock = qdisc_lock(qdisc_root_sleeping(sch));
609 spin_lock(root_lock);
610 q->perturbation = nkey;
611 if (!q->filter_list && q->tail)
612 sfq_rehash(sch);
613 spin_unlock(root_lock);
614
615 /* q->perturb_period can change under us from
616 * sfq_change() and sfq_destroy().
617 */
618 period = READ_ONCE(q->perturb_period);
619 if (period)
620 mod_timer(&q->perturb_timer, jiffies + period);
621 rcu_read_unlock();
622}
623
624static int sfq_change(struct Qdisc *sch, struct nlattr *opt,
625 struct netlink_ext_ack *extack)
626{
627 struct sfq_sched_data *q = qdisc_priv(sch);
628 struct tc_sfq_qopt *ctl = nla_data(opt);
629 struct tc_sfq_qopt_v1 *ctl_v1 = NULL;
630 unsigned int qlen, dropped = 0;
631 struct red_parms *p = NULL;
632 struct sk_buff *to_free = NULL;
633 struct sk_buff *tail = NULL;
634
635 if (opt->nla_len < nla_attr_size(sizeof(*ctl)))
636 return -EINVAL;
637 if (opt->nla_len >= nla_attr_size(sizeof(*ctl_v1)))
638 ctl_v1 = nla_data(opt);
639 if (ctl->divisor &&
640 (!is_power_of_2(ctl->divisor) || ctl->divisor > 65536))
641 return -EINVAL;
642
643 if ((int)ctl->quantum < 0) {
644 NL_SET_ERR_MSG_MOD(extack, "invalid quantum");
645 return -EINVAL;
646 }
647 if (ctl_v1 && !red_check_params(ctl_v1->qth_min, ctl_v1->qth_max,
648 ctl_v1->Wlog, ctl_v1->Scell_log, NULL))
649 return -EINVAL;
650 if (ctl_v1 && ctl_v1->qth_min) {
651 p = kmalloc(sizeof(*p), GFP_KERNEL);
652 if (!p)
653 return -ENOMEM;
654 }
655 if (ctl->limit == 1) {
656 NL_SET_ERR_MSG_MOD(extack, "invalid limit");
657 return -EINVAL;
658 }
659 sch_tree_lock(sch);
660 if (ctl->quantum)
661 q->quantum = ctl->quantum;
662 WRITE_ONCE(q->perturb_period, ctl->perturb_period * HZ);
663 if (ctl->flows)
664 q->maxflows = min_t(u32, ctl->flows, SFQ_MAX_FLOWS);
665 if (ctl->divisor) {
666 q->divisor = ctl->divisor;
667 q->maxflows = min_t(u32, q->maxflows, q->divisor);
668 }
669 if (ctl_v1) {
670 if (ctl_v1->depth)
671 q->maxdepth = min_t(u32, ctl_v1->depth, SFQ_MAX_DEPTH);
672 if (p) {
673 swap(q->red_parms, p);
674 red_set_parms(q->red_parms,
675 ctl_v1->qth_min, ctl_v1->qth_max,
676 ctl_v1->Wlog,
677 ctl_v1->Plog, ctl_v1->Scell_log,
678 NULL,
679 ctl_v1->max_P);
680 }
681 q->flags = ctl_v1->flags;
682 q->headdrop = ctl_v1->headdrop;
683 }
684 if (ctl->limit) {
685 q->limit = min_t(u32, ctl->limit, q->maxdepth * q->maxflows);
686 q->maxflows = min_t(u32, q->maxflows, q->limit);
687 }
688
689 qlen = sch->q.qlen;
690 while (sch->q.qlen > q->limit) {
691 dropped += sfq_drop(sch, &to_free);
692 if (!tail)
693 tail = to_free;
694 }
695
696 rtnl_kfree_skbs(to_free, tail);
697 qdisc_tree_reduce_backlog(sch, qlen - sch->q.qlen, dropped);
698
699 del_timer(&q->perturb_timer);
700 if (q->perturb_period) {
701 mod_timer(&q->perturb_timer, jiffies + q->perturb_period);
702 get_random_bytes(&q->perturbation, sizeof(q->perturbation));
703 }
704 sch_tree_unlock(sch);
705 kfree(p);
706 return 0;
707}
708
709static void *sfq_alloc(size_t sz)
710{
711 return kvmalloc(sz, GFP_KERNEL);
712}
713
714static void sfq_free(void *addr)
715{
716 kvfree(addr);
717}
718
719static void sfq_destroy(struct Qdisc *sch)
720{
721 struct sfq_sched_data *q = qdisc_priv(sch);
722
723 tcf_block_put(q->block);
724 WRITE_ONCE(q->perturb_period, 0);
725 del_timer_sync(&q->perturb_timer);
726 sfq_free(q->ht);
727 sfq_free(q->slots);
728 kfree(q->red_parms);
729}
730
731static int sfq_init(struct Qdisc *sch, struct nlattr *opt,
732 struct netlink_ext_ack *extack)
733{
734 struct sfq_sched_data *q = qdisc_priv(sch);
735 int i;
736 int err;
737
738 q->sch = sch;
739 timer_setup(&q->perturb_timer, sfq_perturbation, TIMER_DEFERRABLE);
740
741 err = tcf_block_get(&q->block, &q->filter_list, sch, extack);
742 if (err)
743 return err;
744
745 for (i = 0; i < SFQ_MAX_DEPTH + 1; i++) {
746 q->dep[i].next = i + SFQ_MAX_FLOWS;
747 q->dep[i].prev = i + SFQ_MAX_FLOWS;
748 }
749
750 q->limit = SFQ_MAX_DEPTH;
751 q->maxdepth = SFQ_MAX_DEPTH;
752 q->cur_depth = 0;
753 q->tail = NULL;
754 q->divisor = SFQ_DEFAULT_HASH_DIVISOR;
755 q->maxflows = SFQ_DEFAULT_FLOWS;
756 q->quantum = psched_mtu(qdisc_dev(sch));
757 q->perturb_period = 0;
758 get_random_bytes(&q->perturbation, sizeof(q->perturbation));
759
760 if (opt) {
761 int err = sfq_change(sch, opt, extack);
762 if (err)
763 return err;
764 }
765
766 q->ht = sfq_alloc(sizeof(q->ht[0]) * q->divisor);
767 q->slots = sfq_alloc(sizeof(q->slots[0]) * q->maxflows);
768 if (!q->ht || !q->slots) {
769 /* Note: sfq_destroy() will be called by our caller */
770 return -ENOMEM;
771 }
772
773 for (i = 0; i < q->divisor; i++)
774 q->ht[i] = SFQ_EMPTY_SLOT;
775
776 for (i = 0; i < q->maxflows; i++) {
777 slot_queue_init(&q->slots[i]);
778 sfq_link(q, i);
779 }
780 if (q->limit >= 1)
781 sch->flags |= TCQ_F_CAN_BYPASS;
782 else
783 sch->flags &= ~TCQ_F_CAN_BYPASS;
784 return 0;
785}
786
787static int sfq_dump(struct Qdisc *sch, struct sk_buff *skb)
788{
789 struct sfq_sched_data *q = qdisc_priv(sch);
790 unsigned char *b = skb_tail_pointer(skb);
791 struct tc_sfq_qopt_v1 opt;
792 struct red_parms *p = q->red_parms;
793
794 memset(&opt, 0, sizeof(opt));
795 opt.v0.quantum = q->quantum;
796 opt.v0.perturb_period = q->perturb_period / HZ;
797 opt.v0.limit = q->limit;
798 opt.v0.divisor = q->divisor;
799 opt.v0.flows = q->maxflows;
800 opt.depth = q->maxdepth;
801 opt.headdrop = q->headdrop;
802
803 if (p) {
804 opt.qth_min = p->qth_min >> p->Wlog;
805 opt.qth_max = p->qth_max >> p->Wlog;
806 opt.Wlog = p->Wlog;
807 opt.Plog = p->Plog;
808 opt.Scell_log = p->Scell_log;
809 opt.max_P = p->max_P;
810 }
811 memcpy(&opt.stats, &q->stats, sizeof(opt.stats));
812 opt.flags = q->flags;
813
814 if (nla_put(skb, TCA_OPTIONS, sizeof(opt), &opt))
815 goto nla_put_failure;
816
817 return skb->len;
818
819nla_put_failure:
820 nlmsg_trim(skb, b);
821 return -1;
822}
823
824static struct Qdisc *sfq_leaf(struct Qdisc *sch, unsigned long arg)
825{
826 return NULL;
827}
828
829static unsigned long sfq_find(struct Qdisc *sch, u32 classid)
830{
831 return 0;
832}
833
834static unsigned long sfq_bind(struct Qdisc *sch, unsigned long parent,
835 u32 classid)
836{
837 return 0;
838}
839
840static void sfq_unbind(struct Qdisc *q, unsigned long cl)
841{
842}
843
844static struct tcf_block *sfq_tcf_block(struct Qdisc *sch, unsigned long cl,
845 struct netlink_ext_ack *extack)
846{
847 struct sfq_sched_data *q = qdisc_priv(sch);
848
849 if (cl)
850 return NULL;
851 return q->block;
852}
853
854static int sfq_dump_class(struct Qdisc *sch, unsigned long cl,
855 struct sk_buff *skb, struct tcmsg *tcm)
856{
857 tcm->tcm_handle |= TC_H_MIN(cl);
858 return 0;
859}
860
861static int sfq_dump_class_stats(struct Qdisc *sch, unsigned long cl,
862 struct gnet_dump *d)
863{
864 struct sfq_sched_data *q = qdisc_priv(sch);
865 sfq_index idx = q->ht[cl - 1];
866 struct gnet_stats_queue qs = { 0 };
867 struct tc_sfq_xstats xstats = { 0 };
868
869 if (idx != SFQ_EMPTY_SLOT) {
870 const struct sfq_slot *slot = &q->slots[idx];
871
872 xstats.allot = slot->allot;
873 qs.qlen = slot->qlen;
874 qs.backlog = slot->backlog;
875 }
876 if (gnet_stats_copy_queue(d, NULL, &qs, qs.qlen) < 0)
877 return -1;
878 return gnet_stats_copy_app(d, &xstats, sizeof(xstats));
879}
880
881static void sfq_walk(struct Qdisc *sch, struct qdisc_walker *arg)
882{
883 struct sfq_sched_data *q = qdisc_priv(sch);
884 unsigned int i;
885
886 if (arg->stop)
887 return;
888
889 for (i = 0; i < q->divisor; i++) {
890 if (q->ht[i] == SFQ_EMPTY_SLOT) {
891 arg->count++;
892 continue;
893 }
894 if (!tc_qdisc_stats_dump(sch, i + 1, arg))
895 break;
896 }
897}
898
899static const struct Qdisc_class_ops sfq_class_ops = {
900 .leaf = sfq_leaf,
901 .find = sfq_find,
902 .tcf_block = sfq_tcf_block,
903 .bind_tcf = sfq_bind,
904 .unbind_tcf = sfq_unbind,
905 .dump = sfq_dump_class,
906 .dump_stats = sfq_dump_class_stats,
907 .walk = sfq_walk,
908};
909
910static struct Qdisc_ops sfq_qdisc_ops __read_mostly = {
911 .cl_ops = &sfq_class_ops,
912 .id = "sfq",
913 .priv_size = sizeof(struct sfq_sched_data),
914 .enqueue = sfq_enqueue,
915 .dequeue = sfq_dequeue,
916 .peek = qdisc_peek_dequeued,
917 .init = sfq_init,
918 .reset = sfq_reset,
919 .destroy = sfq_destroy,
920 .change = NULL,
921 .dump = sfq_dump,
922 .owner = THIS_MODULE,
923};
924MODULE_ALIAS_NET_SCH("sfq");
925
926static int __init sfq_module_init(void)
927{
928 return register_qdisc(&sfq_qdisc_ops);
929}
930static void __exit sfq_module_exit(void)
931{
932 unregister_qdisc(&sfq_qdisc_ops);
933}
934module_init(sfq_module_init)
935module_exit(sfq_module_exit)
936MODULE_LICENSE("GPL");
937MODULE_DESCRIPTION("Stochastic Fairness qdisc");
1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * net/sched/sch_sfq.c Stochastic Fairness Queueing discipline.
4 *
5 * Authors: Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
6 */
7
8#include <linux/module.h>
9#include <linux/types.h>
10#include <linux/kernel.h>
11#include <linux/jiffies.h>
12#include <linux/string.h>
13#include <linux/in.h>
14#include <linux/errno.h>
15#include <linux/init.h>
16#include <linux/skbuff.h>
17#include <linux/siphash.h>
18#include <linux/slab.h>
19#include <linux/vmalloc.h>
20#include <net/netlink.h>
21#include <net/pkt_sched.h>
22#include <net/pkt_cls.h>
23#include <net/red.h>
24
25
26/* Stochastic Fairness Queuing algorithm.
27 =======================================
28
29 Source:
30 Paul E. McKenney "Stochastic Fairness Queuing",
31 IEEE INFOCOMM'90 Proceedings, San Francisco, 1990.
32
33 Paul E. McKenney "Stochastic Fairness Queuing",
34 "Interworking: Research and Experience", v.2, 1991, p.113-131.
35
36
37 See also:
38 M. Shreedhar and George Varghese "Efficient Fair
39 Queuing using Deficit Round Robin", Proc. SIGCOMM 95.
40
41
42 This is not the thing that is usually called (W)FQ nowadays.
43 It does not use any timestamp mechanism, but instead
44 processes queues in round-robin order.
45
46 ADVANTAGE:
47
48 - It is very cheap. Both CPU and memory requirements are minimal.
49
50 DRAWBACKS:
51
52 - "Stochastic" -> It is not 100% fair.
53 When hash collisions occur, several flows are considered as one.
54
55 - "Round-robin" -> It introduces larger delays than virtual clock
56 based schemes, and should not be used for isolating interactive
57 traffic from non-interactive. It means, that this scheduler
58 should be used as leaf of CBQ or P3, which put interactive traffic
59 to higher priority band.
60
61 We still need true WFQ for top level CSZ, but using WFQ
62 for the best effort traffic is absolutely pointless:
63 SFQ is superior for this purpose.
64
65 IMPLEMENTATION:
66 This implementation limits :
67 - maximal queue length per flow to 127 packets.
68 - max mtu to 2^18-1;
69 - max 65408 flows,
70 - number of hash buckets to 65536.
71
72 It is easy to increase these values, but not in flight. */
73
74#define SFQ_MAX_DEPTH 127 /* max number of packets per flow */
75#define SFQ_DEFAULT_FLOWS 128
76#define SFQ_MAX_FLOWS (0x10000 - SFQ_MAX_DEPTH - 1) /* max number of flows */
77#define SFQ_EMPTY_SLOT 0xffff
78#define SFQ_DEFAULT_HASH_DIVISOR 1024
79
80/* We use 16 bits to store allot, and want to handle packets up to 64K
81 * Scale allot by 8 (1<<3) so that no overflow occurs.
82 */
83#define SFQ_ALLOT_SHIFT 3
84#define SFQ_ALLOT_SIZE(X) DIV_ROUND_UP(X, 1 << SFQ_ALLOT_SHIFT)
85
86/* This type should contain at least SFQ_MAX_DEPTH + 1 + SFQ_MAX_FLOWS values */
87typedef u16 sfq_index;
88
89/*
90 * We dont use pointers to save space.
91 * Small indexes [0 ... SFQ_MAX_FLOWS - 1] are 'pointers' to slots[] array
92 * while following values [SFQ_MAX_FLOWS ... SFQ_MAX_FLOWS + SFQ_MAX_DEPTH]
93 * are 'pointers' to dep[] array
94 */
95struct sfq_head {
96 sfq_index next;
97 sfq_index prev;
98};
99
100struct sfq_slot {
101 struct sk_buff *skblist_next;
102 struct sk_buff *skblist_prev;
103 sfq_index qlen; /* number of skbs in skblist */
104 sfq_index next; /* next slot in sfq RR chain */
105 struct sfq_head dep; /* anchor in dep[] chains */
106 unsigned short hash; /* hash value (index in ht[]) */
107 short allot; /* credit for this slot */
108
109 unsigned int backlog;
110 struct red_vars vars;
111};
112
113struct sfq_sched_data {
114/* frequently used fields */
115 int limit; /* limit of total number of packets in this qdisc */
116 unsigned int divisor; /* number of slots in hash table */
117 u8 headdrop;
118 u8 maxdepth; /* limit of packets per flow */
119
120 siphash_key_t perturbation;
121 u8 cur_depth; /* depth of longest slot */
122 u8 flags;
123 unsigned short scaled_quantum; /* SFQ_ALLOT_SIZE(quantum) */
124 struct tcf_proto __rcu *filter_list;
125 struct tcf_block *block;
126 sfq_index *ht; /* Hash table ('divisor' slots) */
127 struct sfq_slot *slots; /* Flows table ('maxflows' entries) */
128
129 struct red_parms *red_parms;
130 struct tc_sfqred_stats stats;
131 struct sfq_slot *tail; /* current slot in round */
132
133 struct sfq_head dep[SFQ_MAX_DEPTH + 1];
134 /* Linked lists of slots, indexed by depth
135 * dep[0] : list of unused flows
136 * dep[1] : list of flows with 1 packet
137 * dep[X] : list of flows with X packets
138 */
139
140 unsigned int maxflows; /* number of flows in flows array */
141 int perturb_period;
142 unsigned int quantum; /* Allotment per round: MUST BE >= MTU */
143 struct timer_list perturb_timer;
144 struct Qdisc *sch;
145};
146
147/*
148 * sfq_head are either in a sfq_slot or in dep[] array
149 */
150static inline struct sfq_head *sfq_dep_head(struct sfq_sched_data *q, sfq_index val)
151{
152 if (val < SFQ_MAX_FLOWS)
153 return &q->slots[val].dep;
154 return &q->dep[val - SFQ_MAX_FLOWS];
155}
156
157static unsigned int sfq_hash(const struct sfq_sched_data *q,
158 const struct sk_buff *skb)
159{
160 return skb_get_hash_perturb(skb, &q->perturbation) & (q->divisor - 1);
161}
162
163static unsigned int sfq_classify(struct sk_buff *skb, struct Qdisc *sch,
164 int *qerr)
165{
166 struct sfq_sched_data *q = qdisc_priv(sch);
167 struct tcf_result res;
168 struct tcf_proto *fl;
169 int result;
170
171 if (TC_H_MAJ(skb->priority) == sch->handle &&
172 TC_H_MIN(skb->priority) > 0 &&
173 TC_H_MIN(skb->priority) <= q->divisor)
174 return TC_H_MIN(skb->priority);
175
176 fl = rcu_dereference_bh(q->filter_list);
177 if (!fl)
178 return sfq_hash(q, skb) + 1;
179
180 *qerr = NET_XMIT_SUCCESS | __NET_XMIT_BYPASS;
181 result = tcf_classify(skb, fl, &res, false);
182 if (result >= 0) {
183#ifdef CONFIG_NET_CLS_ACT
184 switch (result) {
185 case TC_ACT_STOLEN:
186 case TC_ACT_QUEUED:
187 case TC_ACT_TRAP:
188 *qerr = NET_XMIT_SUCCESS | __NET_XMIT_STOLEN;
189 fallthrough;
190 case TC_ACT_SHOT:
191 return 0;
192 }
193#endif
194 if (TC_H_MIN(res.classid) <= q->divisor)
195 return TC_H_MIN(res.classid);
196 }
197 return 0;
198}
199
200/*
201 * x : slot number [0 .. SFQ_MAX_FLOWS - 1]
202 */
203static inline void sfq_link(struct sfq_sched_data *q, sfq_index x)
204{
205 sfq_index p, n;
206 struct sfq_slot *slot = &q->slots[x];
207 int qlen = slot->qlen;
208
209 p = qlen + SFQ_MAX_FLOWS;
210 n = q->dep[qlen].next;
211
212 slot->dep.next = n;
213 slot->dep.prev = p;
214
215 q->dep[qlen].next = x; /* sfq_dep_head(q, p)->next = x */
216 sfq_dep_head(q, n)->prev = x;
217}
218
219#define sfq_unlink(q, x, n, p) \
220 do { \
221 n = q->slots[x].dep.next; \
222 p = q->slots[x].dep.prev; \
223 sfq_dep_head(q, p)->next = n; \
224 sfq_dep_head(q, n)->prev = p; \
225 } while (0)
226
227
228static inline void sfq_dec(struct sfq_sched_data *q, sfq_index x)
229{
230 sfq_index p, n;
231 int d;
232
233 sfq_unlink(q, x, n, p);
234
235 d = q->slots[x].qlen--;
236 if (n == p && q->cur_depth == d)
237 q->cur_depth--;
238 sfq_link(q, x);
239}
240
241static inline void sfq_inc(struct sfq_sched_data *q, sfq_index x)
242{
243 sfq_index p, n;
244 int d;
245
246 sfq_unlink(q, x, n, p);
247
248 d = ++q->slots[x].qlen;
249 if (q->cur_depth < d)
250 q->cur_depth = d;
251 sfq_link(q, x);
252}
253
254/* helper functions : might be changed when/if skb use a standard list_head */
255
256/* remove one skb from tail of slot queue */
257static inline struct sk_buff *slot_dequeue_tail(struct sfq_slot *slot)
258{
259 struct sk_buff *skb = slot->skblist_prev;
260
261 slot->skblist_prev = skb->prev;
262 skb->prev->next = (struct sk_buff *)slot;
263 skb->next = skb->prev = NULL;
264 return skb;
265}
266
267/* remove one skb from head of slot queue */
268static inline struct sk_buff *slot_dequeue_head(struct sfq_slot *slot)
269{
270 struct sk_buff *skb = slot->skblist_next;
271
272 slot->skblist_next = skb->next;
273 skb->next->prev = (struct sk_buff *)slot;
274 skb->next = skb->prev = NULL;
275 return skb;
276}
277
278static inline void slot_queue_init(struct sfq_slot *slot)
279{
280 memset(slot, 0, sizeof(*slot));
281 slot->skblist_prev = slot->skblist_next = (struct sk_buff *)slot;
282}
283
284/* add skb to slot queue (tail add) */
285static inline void slot_queue_add(struct sfq_slot *slot, struct sk_buff *skb)
286{
287 skb->prev = slot->skblist_prev;
288 skb->next = (struct sk_buff *)slot;
289 slot->skblist_prev->next = skb;
290 slot->skblist_prev = skb;
291}
292
293static unsigned int sfq_drop(struct Qdisc *sch, struct sk_buff **to_free)
294{
295 struct sfq_sched_data *q = qdisc_priv(sch);
296 sfq_index x, d = q->cur_depth;
297 struct sk_buff *skb;
298 unsigned int len;
299 struct sfq_slot *slot;
300
301 /* Queue is full! Find the longest slot and drop tail packet from it */
302 if (d > 1) {
303 x = q->dep[d].next;
304 slot = &q->slots[x];
305drop:
306 skb = q->headdrop ? slot_dequeue_head(slot) : slot_dequeue_tail(slot);
307 len = qdisc_pkt_len(skb);
308 slot->backlog -= len;
309 sfq_dec(q, x);
310 sch->q.qlen--;
311 qdisc_qstats_backlog_dec(sch, skb);
312 qdisc_drop(skb, sch, to_free);
313 return len;
314 }
315
316 if (d == 1) {
317 /* It is difficult to believe, but ALL THE SLOTS HAVE LENGTH 1. */
318 x = q->tail->next;
319 slot = &q->slots[x];
320 q->tail->next = slot->next;
321 q->ht[slot->hash] = SFQ_EMPTY_SLOT;
322 goto drop;
323 }
324
325 return 0;
326}
327
328/* Is ECN parameter configured */
329static int sfq_prob_mark(const struct sfq_sched_data *q)
330{
331 return q->flags & TC_RED_ECN;
332}
333
334/* Should packets over max threshold just be marked */
335static int sfq_hard_mark(const struct sfq_sched_data *q)
336{
337 return (q->flags & (TC_RED_ECN | TC_RED_HARDDROP)) == TC_RED_ECN;
338}
339
340static int sfq_headdrop(const struct sfq_sched_data *q)
341{
342 return q->headdrop;
343}
344
345static int
346sfq_enqueue(struct sk_buff *skb, struct Qdisc *sch, struct sk_buff **to_free)
347{
348 struct sfq_sched_data *q = qdisc_priv(sch);
349 unsigned int hash, dropped;
350 sfq_index x, qlen;
351 struct sfq_slot *slot;
352 int ret;
353 struct sk_buff *head;
354 int delta;
355
356 hash = sfq_classify(skb, sch, &ret);
357 if (hash == 0) {
358 if (ret & __NET_XMIT_BYPASS)
359 qdisc_qstats_drop(sch);
360 __qdisc_drop(skb, to_free);
361 return ret;
362 }
363 hash--;
364
365 x = q->ht[hash];
366 slot = &q->slots[x];
367 if (x == SFQ_EMPTY_SLOT) {
368 x = q->dep[0].next; /* get a free slot */
369 if (x >= SFQ_MAX_FLOWS)
370 return qdisc_drop(skb, sch, to_free);
371 q->ht[hash] = x;
372 slot = &q->slots[x];
373 slot->hash = hash;
374 slot->backlog = 0; /* should already be 0 anyway... */
375 red_set_vars(&slot->vars);
376 goto enqueue;
377 }
378 if (q->red_parms) {
379 slot->vars.qavg = red_calc_qavg_no_idle_time(q->red_parms,
380 &slot->vars,
381 slot->backlog);
382 switch (red_action(q->red_parms,
383 &slot->vars,
384 slot->vars.qavg)) {
385 case RED_DONT_MARK:
386 break;
387
388 case RED_PROB_MARK:
389 qdisc_qstats_overlimit(sch);
390 if (sfq_prob_mark(q)) {
391 /* We know we have at least one packet in queue */
392 if (sfq_headdrop(q) &&
393 INET_ECN_set_ce(slot->skblist_next)) {
394 q->stats.prob_mark_head++;
395 break;
396 }
397 if (INET_ECN_set_ce(skb)) {
398 q->stats.prob_mark++;
399 break;
400 }
401 }
402 q->stats.prob_drop++;
403 goto congestion_drop;
404
405 case RED_HARD_MARK:
406 qdisc_qstats_overlimit(sch);
407 if (sfq_hard_mark(q)) {
408 /* We know we have at least one packet in queue */
409 if (sfq_headdrop(q) &&
410 INET_ECN_set_ce(slot->skblist_next)) {
411 q->stats.forced_mark_head++;
412 break;
413 }
414 if (INET_ECN_set_ce(skb)) {
415 q->stats.forced_mark++;
416 break;
417 }
418 }
419 q->stats.forced_drop++;
420 goto congestion_drop;
421 }
422 }
423
424 if (slot->qlen >= q->maxdepth) {
425congestion_drop:
426 if (!sfq_headdrop(q))
427 return qdisc_drop(skb, sch, to_free);
428
429 /* We know we have at least one packet in queue */
430 head = slot_dequeue_head(slot);
431 delta = qdisc_pkt_len(head) - qdisc_pkt_len(skb);
432 sch->qstats.backlog -= delta;
433 slot->backlog -= delta;
434 qdisc_drop(head, sch, to_free);
435
436 slot_queue_add(slot, skb);
437 qdisc_tree_reduce_backlog(sch, 0, delta);
438 return NET_XMIT_CN;
439 }
440
441enqueue:
442 qdisc_qstats_backlog_inc(sch, skb);
443 slot->backlog += qdisc_pkt_len(skb);
444 slot_queue_add(slot, skb);
445 sfq_inc(q, x);
446 if (slot->qlen == 1) { /* The flow is new */
447 if (q->tail == NULL) { /* It is the first flow */
448 slot->next = x;
449 } else {
450 slot->next = q->tail->next;
451 q->tail->next = x;
452 }
453 /* We put this flow at the end of our flow list.
454 * This might sound unfair for a new flow to wait after old ones,
455 * but we could endup servicing new flows only, and freeze old ones.
456 */
457 q->tail = slot;
458 /* We could use a bigger initial quantum for new flows */
459 slot->allot = q->scaled_quantum;
460 }
461 if (++sch->q.qlen <= q->limit)
462 return NET_XMIT_SUCCESS;
463
464 qlen = slot->qlen;
465 dropped = sfq_drop(sch, to_free);
466 /* Return Congestion Notification only if we dropped a packet
467 * from this flow.
468 */
469 if (qlen != slot->qlen) {
470 qdisc_tree_reduce_backlog(sch, 0, dropped - qdisc_pkt_len(skb));
471 return NET_XMIT_CN;
472 }
473
474 /* As we dropped a packet, better let upper stack know this */
475 qdisc_tree_reduce_backlog(sch, 1, dropped);
476 return NET_XMIT_SUCCESS;
477}
478
479static struct sk_buff *
480sfq_dequeue(struct Qdisc *sch)
481{
482 struct sfq_sched_data *q = qdisc_priv(sch);
483 struct sk_buff *skb;
484 sfq_index a, next_a;
485 struct sfq_slot *slot;
486
487 /* No active slots */
488 if (q->tail == NULL)
489 return NULL;
490
491next_slot:
492 a = q->tail->next;
493 slot = &q->slots[a];
494 if (slot->allot <= 0) {
495 q->tail = slot;
496 slot->allot += q->scaled_quantum;
497 goto next_slot;
498 }
499 skb = slot_dequeue_head(slot);
500 sfq_dec(q, a);
501 qdisc_bstats_update(sch, skb);
502 sch->q.qlen--;
503 qdisc_qstats_backlog_dec(sch, skb);
504 slot->backlog -= qdisc_pkt_len(skb);
505 /* Is the slot empty? */
506 if (slot->qlen == 0) {
507 q->ht[slot->hash] = SFQ_EMPTY_SLOT;
508 next_a = slot->next;
509 if (a == next_a) {
510 q->tail = NULL; /* no more active slots */
511 return skb;
512 }
513 q->tail->next = next_a;
514 } else {
515 slot->allot -= SFQ_ALLOT_SIZE(qdisc_pkt_len(skb));
516 }
517 return skb;
518}
519
520static void
521sfq_reset(struct Qdisc *sch)
522{
523 struct sk_buff *skb;
524
525 while ((skb = sfq_dequeue(sch)) != NULL)
526 rtnl_kfree_skbs(skb, skb);
527}
528
529/*
530 * When q->perturbation is changed, we rehash all queued skbs
531 * to avoid OOO (Out Of Order) effects.
532 * We dont use sfq_dequeue()/sfq_enqueue() because we dont want to change
533 * counters.
534 */
535static void sfq_rehash(struct Qdisc *sch)
536{
537 struct sfq_sched_data *q = qdisc_priv(sch);
538 struct sk_buff *skb;
539 int i;
540 struct sfq_slot *slot;
541 struct sk_buff_head list;
542 int dropped = 0;
543 unsigned int drop_len = 0;
544
545 __skb_queue_head_init(&list);
546
547 for (i = 0; i < q->maxflows; i++) {
548 slot = &q->slots[i];
549 if (!slot->qlen)
550 continue;
551 while (slot->qlen) {
552 skb = slot_dequeue_head(slot);
553 sfq_dec(q, i);
554 __skb_queue_tail(&list, skb);
555 }
556 slot->backlog = 0;
557 red_set_vars(&slot->vars);
558 q->ht[slot->hash] = SFQ_EMPTY_SLOT;
559 }
560 q->tail = NULL;
561
562 while ((skb = __skb_dequeue(&list)) != NULL) {
563 unsigned int hash = sfq_hash(q, skb);
564 sfq_index x = q->ht[hash];
565
566 slot = &q->slots[x];
567 if (x == SFQ_EMPTY_SLOT) {
568 x = q->dep[0].next; /* get a free slot */
569 if (x >= SFQ_MAX_FLOWS) {
570drop:
571 qdisc_qstats_backlog_dec(sch, skb);
572 drop_len += qdisc_pkt_len(skb);
573 kfree_skb(skb);
574 dropped++;
575 continue;
576 }
577 q->ht[hash] = x;
578 slot = &q->slots[x];
579 slot->hash = hash;
580 }
581 if (slot->qlen >= q->maxdepth)
582 goto drop;
583 slot_queue_add(slot, skb);
584 if (q->red_parms)
585 slot->vars.qavg = red_calc_qavg(q->red_parms,
586 &slot->vars,
587 slot->backlog);
588 slot->backlog += qdisc_pkt_len(skb);
589 sfq_inc(q, x);
590 if (slot->qlen == 1) { /* The flow is new */
591 if (q->tail == NULL) { /* It is the first flow */
592 slot->next = x;
593 } else {
594 slot->next = q->tail->next;
595 q->tail->next = x;
596 }
597 q->tail = slot;
598 slot->allot = q->scaled_quantum;
599 }
600 }
601 sch->q.qlen -= dropped;
602 qdisc_tree_reduce_backlog(sch, dropped, drop_len);
603}
604
605static void sfq_perturbation(struct timer_list *t)
606{
607 struct sfq_sched_data *q = from_timer(q, t, perturb_timer);
608 struct Qdisc *sch = q->sch;
609 spinlock_t *root_lock = qdisc_lock(qdisc_root_sleeping(sch));
610 siphash_key_t nkey;
611
612 get_random_bytes(&nkey, sizeof(nkey));
613 spin_lock(root_lock);
614 q->perturbation = nkey;
615 if (!q->filter_list && q->tail)
616 sfq_rehash(sch);
617 spin_unlock(root_lock);
618
619 if (q->perturb_period)
620 mod_timer(&q->perturb_timer, jiffies + q->perturb_period);
621}
622
623static int sfq_change(struct Qdisc *sch, struct nlattr *opt)
624{
625 struct sfq_sched_data *q = qdisc_priv(sch);
626 struct tc_sfq_qopt *ctl = nla_data(opt);
627 struct tc_sfq_qopt_v1 *ctl_v1 = NULL;
628 unsigned int qlen, dropped = 0;
629 struct red_parms *p = NULL;
630 struct sk_buff *to_free = NULL;
631 struct sk_buff *tail = NULL;
632
633 if (opt->nla_len < nla_attr_size(sizeof(*ctl)))
634 return -EINVAL;
635 if (opt->nla_len >= nla_attr_size(sizeof(*ctl_v1)))
636 ctl_v1 = nla_data(opt);
637 if (ctl->divisor &&
638 (!is_power_of_2(ctl->divisor) || ctl->divisor > 65536))
639 return -EINVAL;
640
641 /* slot->allot is a short, make sure quantum is not too big. */
642 if (ctl->quantum) {
643 unsigned int scaled = SFQ_ALLOT_SIZE(ctl->quantum);
644
645 if (scaled <= 0 || scaled > SHRT_MAX)
646 return -EINVAL;
647 }
648
649 if (ctl_v1 && !red_check_params(ctl_v1->qth_min, ctl_v1->qth_max,
650 ctl_v1->Wlog))
651 return -EINVAL;
652 if (ctl_v1 && ctl_v1->qth_min) {
653 p = kmalloc(sizeof(*p), GFP_KERNEL);
654 if (!p)
655 return -ENOMEM;
656 }
657 sch_tree_lock(sch);
658 if (ctl->quantum) {
659 q->quantum = ctl->quantum;
660 q->scaled_quantum = SFQ_ALLOT_SIZE(q->quantum);
661 }
662 q->perturb_period = ctl->perturb_period * HZ;
663 if (ctl->flows)
664 q->maxflows = min_t(u32, ctl->flows, SFQ_MAX_FLOWS);
665 if (ctl->divisor) {
666 q->divisor = ctl->divisor;
667 q->maxflows = min_t(u32, q->maxflows, q->divisor);
668 }
669 if (ctl_v1) {
670 if (ctl_v1->depth)
671 q->maxdepth = min_t(u32, ctl_v1->depth, SFQ_MAX_DEPTH);
672 if (p) {
673 swap(q->red_parms, p);
674 red_set_parms(q->red_parms,
675 ctl_v1->qth_min, ctl_v1->qth_max,
676 ctl_v1->Wlog,
677 ctl_v1->Plog, ctl_v1->Scell_log,
678 NULL,
679 ctl_v1->max_P);
680 }
681 q->flags = ctl_v1->flags;
682 q->headdrop = ctl_v1->headdrop;
683 }
684 if (ctl->limit) {
685 q->limit = min_t(u32, ctl->limit, q->maxdepth * q->maxflows);
686 q->maxflows = min_t(u32, q->maxflows, q->limit);
687 }
688
689 qlen = sch->q.qlen;
690 while (sch->q.qlen > q->limit) {
691 dropped += sfq_drop(sch, &to_free);
692 if (!tail)
693 tail = to_free;
694 }
695
696 rtnl_kfree_skbs(to_free, tail);
697 qdisc_tree_reduce_backlog(sch, qlen - sch->q.qlen, dropped);
698
699 del_timer(&q->perturb_timer);
700 if (q->perturb_period) {
701 mod_timer(&q->perturb_timer, jiffies + q->perturb_period);
702 get_random_bytes(&q->perturbation, sizeof(q->perturbation));
703 }
704 sch_tree_unlock(sch);
705 kfree(p);
706 return 0;
707}
708
709static void *sfq_alloc(size_t sz)
710{
711 return kvmalloc(sz, GFP_KERNEL);
712}
713
714static void sfq_free(void *addr)
715{
716 kvfree(addr);
717}
718
719static void sfq_destroy(struct Qdisc *sch)
720{
721 struct sfq_sched_data *q = qdisc_priv(sch);
722
723 tcf_block_put(q->block);
724 q->perturb_period = 0;
725 del_timer_sync(&q->perturb_timer);
726 sfq_free(q->ht);
727 sfq_free(q->slots);
728 kfree(q->red_parms);
729}
730
731static int sfq_init(struct Qdisc *sch, struct nlattr *opt,
732 struct netlink_ext_ack *extack)
733{
734 struct sfq_sched_data *q = qdisc_priv(sch);
735 int i;
736 int err;
737
738 q->sch = sch;
739 timer_setup(&q->perturb_timer, sfq_perturbation, TIMER_DEFERRABLE);
740
741 err = tcf_block_get(&q->block, &q->filter_list, sch, extack);
742 if (err)
743 return err;
744
745 for (i = 0; i < SFQ_MAX_DEPTH + 1; i++) {
746 q->dep[i].next = i + SFQ_MAX_FLOWS;
747 q->dep[i].prev = i + SFQ_MAX_FLOWS;
748 }
749
750 q->limit = SFQ_MAX_DEPTH;
751 q->maxdepth = SFQ_MAX_DEPTH;
752 q->cur_depth = 0;
753 q->tail = NULL;
754 q->divisor = SFQ_DEFAULT_HASH_DIVISOR;
755 q->maxflows = SFQ_DEFAULT_FLOWS;
756 q->quantum = psched_mtu(qdisc_dev(sch));
757 q->scaled_quantum = SFQ_ALLOT_SIZE(q->quantum);
758 q->perturb_period = 0;
759 get_random_bytes(&q->perturbation, sizeof(q->perturbation));
760
761 if (opt) {
762 int err = sfq_change(sch, opt);
763 if (err)
764 return err;
765 }
766
767 q->ht = sfq_alloc(sizeof(q->ht[0]) * q->divisor);
768 q->slots = sfq_alloc(sizeof(q->slots[0]) * q->maxflows);
769 if (!q->ht || !q->slots) {
770 /* Note: sfq_destroy() will be called by our caller */
771 return -ENOMEM;
772 }
773
774 for (i = 0; i < q->divisor; i++)
775 q->ht[i] = SFQ_EMPTY_SLOT;
776
777 for (i = 0; i < q->maxflows; i++) {
778 slot_queue_init(&q->slots[i]);
779 sfq_link(q, i);
780 }
781 if (q->limit >= 1)
782 sch->flags |= TCQ_F_CAN_BYPASS;
783 else
784 sch->flags &= ~TCQ_F_CAN_BYPASS;
785 return 0;
786}
787
788static int sfq_dump(struct Qdisc *sch, struct sk_buff *skb)
789{
790 struct sfq_sched_data *q = qdisc_priv(sch);
791 unsigned char *b = skb_tail_pointer(skb);
792 struct tc_sfq_qopt_v1 opt;
793 struct red_parms *p = q->red_parms;
794
795 memset(&opt, 0, sizeof(opt));
796 opt.v0.quantum = q->quantum;
797 opt.v0.perturb_period = q->perturb_period / HZ;
798 opt.v0.limit = q->limit;
799 opt.v0.divisor = q->divisor;
800 opt.v0.flows = q->maxflows;
801 opt.depth = q->maxdepth;
802 opt.headdrop = q->headdrop;
803
804 if (p) {
805 opt.qth_min = p->qth_min >> p->Wlog;
806 opt.qth_max = p->qth_max >> p->Wlog;
807 opt.Wlog = p->Wlog;
808 opt.Plog = p->Plog;
809 opt.Scell_log = p->Scell_log;
810 opt.max_P = p->max_P;
811 }
812 memcpy(&opt.stats, &q->stats, sizeof(opt.stats));
813 opt.flags = q->flags;
814
815 if (nla_put(skb, TCA_OPTIONS, sizeof(opt), &opt))
816 goto nla_put_failure;
817
818 return skb->len;
819
820nla_put_failure:
821 nlmsg_trim(skb, b);
822 return -1;
823}
824
825static struct Qdisc *sfq_leaf(struct Qdisc *sch, unsigned long arg)
826{
827 return NULL;
828}
829
830static unsigned long sfq_find(struct Qdisc *sch, u32 classid)
831{
832 return 0;
833}
834
835static unsigned long sfq_bind(struct Qdisc *sch, unsigned long parent,
836 u32 classid)
837{
838 return 0;
839}
840
841static void sfq_unbind(struct Qdisc *q, unsigned long cl)
842{
843}
844
845static struct tcf_block *sfq_tcf_block(struct Qdisc *sch, unsigned long cl,
846 struct netlink_ext_ack *extack)
847{
848 struct sfq_sched_data *q = qdisc_priv(sch);
849
850 if (cl)
851 return NULL;
852 return q->block;
853}
854
855static int sfq_dump_class(struct Qdisc *sch, unsigned long cl,
856 struct sk_buff *skb, struct tcmsg *tcm)
857{
858 tcm->tcm_handle |= TC_H_MIN(cl);
859 return 0;
860}
861
862static int sfq_dump_class_stats(struct Qdisc *sch, unsigned long cl,
863 struct gnet_dump *d)
864{
865 struct sfq_sched_data *q = qdisc_priv(sch);
866 sfq_index idx = q->ht[cl - 1];
867 struct gnet_stats_queue qs = { 0 };
868 struct tc_sfq_xstats xstats = { 0 };
869
870 if (idx != SFQ_EMPTY_SLOT) {
871 const struct sfq_slot *slot = &q->slots[idx];
872
873 xstats.allot = slot->allot << SFQ_ALLOT_SHIFT;
874 qs.qlen = slot->qlen;
875 qs.backlog = slot->backlog;
876 }
877 if (gnet_stats_copy_queue(d, NULL, &qs, qs.qlen) < 0)
878 return -1;
879 return gnet_stats_copy_app(d, &xstats, sizeof(xstats));
880}
881
882static void sfq_walk(struct Qdisc *sch, struct qdisc_walker *arg)
883{
884 struct sfq_sched_data *q = qdisc_priv(sch);
885 unsigned int i;
886
887 if (arg->stop)
888 return;
889
890 for (i = 0; i < q->divisor; i++) {
891 if (q->ht[i] == SFQ_EMPTY_SLOT ||
892 arg->count < arg->skip) {
893 arg->count++;
894 continue;
895 }
896 if (arg->fn(sch, i + 1, arg) < 0) {
897 arg->stop = 1;
898 break;
899 }
900 arg->count++;
901 }
902}
903
904static const struct Qdisc_class_ops sfq_class_ops = {
905 .leaf = sfq_leaf,
906 .find = sfq_find,
907 .tcf_block = sfq_tcf_block,
908 .bind_tcf = sfq_bind,
909 .unbind_tcf = sfq_unbind,
910 .dump = sfq_dump_class,
911 .dump_stats = sfq_dump_class_stats,
912 .walk = sfq_walk,
913};
914
915static struct Qdisc_ops sfq_qdisc_ops __read_mostly = {
916 .cl_ops = &sfq_class_ops,
917 .id = "sfq",
918 .priv_size = sizeof(struct sfq_sched_data),
919 .enqueue = sfq_enqueue,
920 .dequeue = sfq_dequeue,
921 .peek = qdisc_peek_dequeued,
922 .init = sfq_init,
923 .reset = sfq_reset,
924 .destroy = sfq_destroy,
925 .change = NULL,
926 .dump = sfq_dump,
927 .owner = THIS_MODULE,
928};
929
930static int __init sfq_module_init(void)
931{
932 return register_qdisc(&sfq_qdisc_ops);
933}
934static void __exit sfq_module_exit(void)
935{
936 unregister_qdisc(&sfq_qdisc_ops);
937}
938module_init(sfq_module_init)
939module_exit(sfq_module_exit)
940MODULE_LICENSE("GPL");