1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * net/sched/sch_red.c Random Early Detection queue.
4 *
5 * Authors: Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
6 *
7 * Changes:
8 * J Hadi Salim 980914: computation fixes
9 * Alexey Makarenko <makar@phoenix.kharkov.ua> 990814: qave on idle link was calculated incorrectly.
10 * J Hadi Salim 980816: ECN support
11 */
12
13 #include <linux/module.h>
14 #include <linux/types.h>
15 #include <linux/kernel.h>
16 #include <linux/skbuff.h>
17 #include <net/pkt_sched.h>
18 #include <net/pkt_cls.h>
19 #include <net/inet_ecn.h>
20 #include <net/red.h>
21
22
23 /* Parameters, settable by user:
24 -----------------------------
25
26 limit - bytes (must be > qth_max + burst)
27
28 Hard limit on queue length, should be chosen >qth_max
29 to allow packet bursts. This parameter does not
30 affect the algorithms behaviour and can be chosen
31 arbitrarily high (well, less than ram size)
32 Really, this limit will never be reached
33 if RED works correctly.
34 */
35
36 struct red_sched_data {
37 u32 limit; /* HARD maximal queue length */
38
39 unsigned char flags;
40 /* Non-flags in tc_red_qopt.flags. */
41 unsigned char userbits;
42
43 struct timer_list adapt_timer;
44 struct Qdisc *sch;
45 struct red_parms parms;
46 struct red_vars vars;
47 struct red_stats stats;
48 struct Qdisc *qdisc;
49 struct tcf_qevent qe_early_drop;
50 struct tcf_qevent qe_mark;
51 };
52
53 #define TC_RED_SUPPORTED_FLAGS (TC_RED_HISTORIC_FLAGS | TC_RED_NODROP)
54
55 static inline int red_use_ecn(struct red_sched_data *q)
56 {
57 return q->flags & TC_RED_ECN;
58 }
59
60 static inline int red_use_harddrop(struct red_sched_data *q)
61 {
62 return q->flags & TC_RED_HARDDROP;
63 }
64
65 static int red_use_nodrop(struct red_sched_data *q)
66 {
67 return q->flags & TC_RED_NODROP;
68 }
69
70 static int red_enqueue(struct sk_buff *skb, struct Qdisc *sch,
71 struct sk_buff **to_free)
72 {
73 struct red_sched_data *q = qdisc_priv(sch);
74 struct Qdisc *child = q->qdisc;
75 unsigned int len;
76 int ret;
77
78 q->vars.qavg = red_calc_qavg(&q->parms,
79 &q->vars,
80 child->qstats.backlog);
81
82 if (red_is_idling(&q->vars))
83 red_end_of_idle_period(&q->vars);
84
85 switch (red_action(&q->parms, &q->vars, q->vars.qavg)) {
86 case RED_DONT_MARK:
87 break;
88
89 case RED_PROB_MARK:
90 qdisc_qstats_overlimit(sch);
91 if (!red_use_ecn(q)) {
92 q->stats.prob_drop++;
93 goto congestion_drop;
94 }
95
96 if (INET_ECN_set_ce(skb)) {
97 q->stats.prob_mark++;
98 skb = tcf_qevent_handle(&q->qe_mark, sch, skb, to_free, &ret);
99 if (!skb)
100 return NET_XMIT_CN | ret;
101 } else if (!red_use_nodrop(q)) {
102 q->stats.prob_drop++;
103 goto congestion_drop;
104 }
105
106 /* Non-ECT packet in ECN nodrop mode: queue it. */
107 break;
108
109 case RED_HARD_MARK:
110 qdisc_qstats_overlimit(sch);
111 if (red_use_harddrop(q) || !red_use_ecn(q)) {
112 q->stats.forced_drop++;
113 goto congestion_drop;
114 }
115
116 if (INET_ECN_set_ce(skb)) {
117 q->stats.forced_mark++;
118 skb = tcf_qevent_handle(&q->qe_mark, sch, skb, to_free, &ret);
119 if (!skb)
120 return NET_XMIT_CN | ret;
121 } else if (!red_use_nodrop(q)) {
122 q->stats.forced_drop++;
123 goto congestion_drop;
124 }
125
126 /* Non-ECT packet in ECN nodrop mode: queue it. */
127 break;
128 }
129
130 len = qdisc_pkt_len(skb);
131 ret = qdisc_enqueue(skb, child, to_free);
132 if (likely(ret == NET_XMIT_SUCCESS)) {
133 sch->qstats.backlog += len;
134 sch->q.qlen++;
135 } else if (net_xmit_drop_count(ret)) {
136 q->stats.pdrop++;
137 qdisc_qstats_drop(sch);
138 }
139 return ret;
140
141 congestion_drop:
142 skb = tcf_qevent_handle(&q->qe_early_drop, sch, skb, to_free, &ret);
143 if (!skb)
144 return NET_XMIT_CN | ret;
145
146 qdisc_drop(skb, sch, to_free);
147 return NET_XMIT_CN;
148 }
149
150 static struct sk_buff *red_dequeue(struct Qdisc *sch)
151 {
152 struct sk_buff *skb;
153 struct red_sched_data *q = qdisc_priv(sch);
154 struct Qdisc *child = q->qdisc;
155
156 skb = child->dequeue(child);
157 if (skb) {
158 qdisc_bstats_update(sch, skb);
159 qdisc_qstats_backlog_dec(sch, skb);
160 sch->q.qlen--;
161 } else {
162 if (!red_is_idling(&q->vars))
163 red_start_of_idle_period(&q->vars);
164 }
165 return skb;
166 }
167
168 static struct sk_buff *red_peek(struct Qdisc *sch)
169 {
170 struct red_sched_data *q = qdisc_priv(sch);
171 struct Qdisc *child = q->qdisc;
172
173 return child->ops->peek(child);
174 }
175
176 static void red_reset(struct Qdisc *sch)
177 {
178 struct red_sched_data *q = qdisc_priv(sch);
179
180 qdisc_reset(q->qdisc);
181 red_restart(&q->vars);
182 }
183
184 static int red_offload(struct Qdisc *sch, bool enable)
185 {
186 struct red_sched_data *q = qdisc_priv(sch);
187 struct net_device *dev = qdisc_dev(sch);
188 struct tc_red_qopt_offload opt = {
189 .handle = sch->handle,
190 .parent = sch->parent,
191 };
192
193 if (!tc_can_offload(dev) || !dev->netdev_ops->ndo_setup_tc)
194 return -EOPNOTSUPP;
195
196 if (enable) {
197 opt.command = TC_RED_REPLACE;
198 opt.set.min = q->parms.qth_min >> q->parms.Wlog;
199 opt.set.max = q->parms.qth_max >> q->parms.Wlog;
200 opt.set.probability = q->parms.max_P;
201 opt.set.limit = q->limit;
202 opt.set.is_ecn = red_use_ecn(q);
203 opt.set.is_harddrop = red_use_harddrop(q);
204 opt.set.is_nodrop = red_use_nodrop(q);
205 opt.set.qstats = &sch->qstats;
206 } else {
207 opt.command = TC_RED_DESTROY;
208 }
209
210 return dev->netdev_ops->ndo_setup_tc(dev, TC_SETUP_QDISC_RED, &opt);
211 }
212
213 static void red_destroy(struct Qdisc *sch)
214 {
215 struct red_sched_data *q = qdisc_priv(sch);
216
217 tcf_qevent_destroy(&q->qe_mark, sch);
218 tcf_qevent_destroy(&q->qe_early_drop, sch);
219 del_timer_sync(&q->adapt_timer);
220 red_offload(sch, false);
221 qdisc_put(q->qdisc);
222 }
223
224 static const struct nla_policy red_policy[TCA_RED_MAX + 1] = {
225 [TCA_RED_UNSPEC] = { .strict_start_type = TCA_RED_FLAGS },
226 [TCA_RED_PARMS] = { .len = sizeof(struct tc_red_qopt) },
227 [TCA_RED_STAB] = { .len = RED_STAB_SIZE },
228 [TCA_RED_MAX_P] = { .type = NLA_U32 },
229 [TCA_RED_FLAGS] = NLA_POLICY_BITFIELD32(TC_RED_SUPPORTED_FLAGS),
230 [TCA_RED_EARLY_DROP_BLOCK] = { .type = NLA_U32 },
231 [TCA_RED_MARK_BLOCK] = { .type = NLA_U32 },
232 };
233
234 static int __red_change(struct Qdisc *sch, struct nlattr **tb,
235 struct netlink_ext_ack *extack)
236 {
237 struct Qdisc *old_child = NULL, *child = NULL;
238 struct red_sched_data *q = qdisc_priv(sch);
239 struct nla_bitfield32 flags_bf;
240 struct tc_red_qopt *ctl;
241 unsigned char userbits;
242 unsigned char flags;
243 int err;
244 u32 max_P;
245 u8 *stab;
246
247 if (tb[TCA_RED_PARMS] == NULL ||
248 tb[TCA_RED_STAB] == NULL)
249 return -EINVAL;
250
251 max_P = tb[TCA_RED_MAX_P] ? nla_get_u32(tb[TCA_RED_MAX_P]) : 0;
252
253 ctl = nla_data(tb[TCA_RED_PARMS]);
254 stab = nla_data(tb[TCA_RED_STAB]);
255 if (!red_check_params(ctl->qth_min, ctl->qth_max, ctl->Wlog,
256 ctl->Scell_log, stab))
257 return -EINVAL;
258
259 err = red_get_flags(ctl->flags, TC_RED_HISTORIC_FLAGS,
260 tb[TCA_RED_FLAGS], TC_RED_SUPPORTED_FLAGS,
261 &flags_bf, &userbits, extack);
262 if (err)
263 return err;
264
265 if (ctl->limit > 0) {
266 child = fifo_create_dflt(sch, &bfifo_qdisc_ops, ctl->limit,
267 extack);
268 if (IS_ERR(child))
269 return PTR_ERR(child);
270
271 /* child is fifo, no need to check for noop_qdisc */
272 qdisc_hash_add(child, true);
273 }
274
275 sch_tree_lock(sch);
276
277 flags = (q->flags & ~flags_bf.selector) | flags_bf.value;
278 err = red_validate_flags(flags, extack);
279 if (err)
280 goto unlock_out;
281
282 q->flags = flags;
283 q->userbits = userbits;
284 q->limit = ctl->limit;
285 if (child) {
286 qdisc_tree_flush_backlog(q->qdisc);
287 old_child = q->qdisc;
288 q->qdisc = child;
289 }
290
291 red_set_parms(&q->parms,
292 ctl->qth_min, ctl->qth_max, ctl->Wlog,
293 ctl->Plog, ctl->Scell_log,
294 stab,
295 max_P);
296 red_set_vars(&q->vars);
297
298 del_timer(&q->adapt_timer);
299 if (ctl->flags & TC_RED_ADAPTATIVE)
300 mod_timer(&q->adapt_timer, jiffies + HZ/2);
301
302 if (!q->qdisc->q.qlen)
303 red_start_of_idle_period(&q->vars);
304
305 sch_tree_unlock(sch);
306
307 red_offload(sch, true);
308
309 if (old_child)
310 qdisc_put(old_child);
311 return 0;
312
313 unlock_out:
314 sch_tree_unlock(sch);
315 if (child)
316 qdisc_put(child);
317 return err;
318 }
319
320 static inline void red_adaptative_timer(struct timer_list *t)
321 {
322 struct red_sched_data *q = from_timer(q, t, adapt_timer);
323 struct Qdisc *sch = q->sch;
324 spinlock_t *root_lock;
325
326 rcu_read_lock();
327 root_lock = qdisc_lock(qdisc_root_sleeping(sch));
328 spin_lock(root_lock);
329 red_adaptative_algo(&q->parms, &q->vars);
330 mod_timer(&q->adapt_timer, jiffies + HZ/2);
331 spin_unlock(root_lock);
332 rcu_read_unlock();
333 }
334
335 static int red_init(struct Qdisc *sch, struct nlattr *opt,
336 struct netlink_ext_ack *extack)
337 {
338 struct red_sched_data *q = qdisc_priv(sch);
339 struct nlattr *tb[TCA_RED_MAX + 1];
340 int err;
341
342 q->qdisc = &noop_qdisc;
343 q->sch = sch;
344 timer_setup(&q->adapt_timer, red_adaptative_timer, 0);
345
346 if (!opt)
347 return -EINVAL;
348
349 err = nla_parse_nested_deprecated(tb, TCA_RED_MAX, opt, red_policy,
350 extack);
351 if (err < 0)
352 return err;
353
354 err = __red_change(sch, tb, extack);
355 if (err)
356 return err;
357
358 err = tcf_qevent_init(&q->qe_early_drop, sch,
359 FLOW_BLOCK_BINDER_TYPE_RED_EARLY_DROP,
360 tb[TCA_RED_EARLY_DROP_BLOCK], extack);
361 if (err)
362 return err;
363
364 return tcf_qevent_init(&q->qe_mark, sch,
365 FLOW_BLOCK_BINDER_TYPE_RED_MARK,
366 tb[TCA_RED_MARK_BLOCK], extack);
367 }
368
369 static int red_change(struct Qdisc *sch, struct nlattr *opt,
370 struct netlink_ext_ack *extack)
371 {
372 struct red_sched_data *q = qdisc_priv(sch);
373 struct nlattr *tb[TCA_RED_MAX + 1];
374 int err;
375
376 err = nla_parse_nested_deprecated(tb, TCA_RED_MAX, opt, red_policy,
377 extack);
378 if (err < 0)
379 return err;
380
381 err = tcf_qevent_validate_change(&q->qe_early_drop,
382 tb[TCA_RED_EARLY_DROP_BLOCK], extack);
383 if (err)
384 return err;
385
386 err = tcf_qevent_validate_change(&q->qe_mark,
387 tb[TCA_RED_MARK_BLOCK], extack);
388 if (err)
389 return err;
390
391 return __red_change(sch, tb, extack);
392 }
393
394 static int red_dump_offload_stats(struct Qdisc *sch)
395 {
396 struct tc_red_qopt_offload hw_stats = {
397 .command = TC_RED_STATS,
398 .handle = sch->handle,
399 .parent = sch->parent,
400 {
401 .stats.bstats = &sch->bstats,
402 .stats.qstats = &sch->qstats,
403 },
404 };
405
406 return qdisc_offload_dump_helper(sch, TC_SETUP_QDISC_RED, &hw_stats);
407 }
408
409 static int red_dump(struct Qdisc *sch, struct sk_buff *skb)
410 {
411 struct red_sched_data *q = qdisc_priv(sch);
412 struct nlattr *opts = NULL;
413 struct tc_red_qopt opt = {
414 .limit = q->limit,
415 .flags = (q->flags & TC_RED_HISTORIC_FLAGS) |
416 q->userbits,
417 .qth_min = q->parms.qth_min >> q->parms.Wlog,
418 .qth_max = q->parms.qth_max >> q->parms.Wlog,
419 .Wlog = q->parms.Wlog,
420 .Plog = q->parms.Plog,
421 .Scell_log = q->parms.Scell_log,
422 };
423 int err;
424
425 err = red_dump_offload_stats(sch);
426 if (err)
427 goto nla_put_failure;
428
429 opts = nla_nest_start_noflag(skb, TCA_OPTIONS);
430 if (opts == NULL)
431 goto nla_put_failure;
432 if (nla_put(skb, TCA_RED_PARMS, sizeof(opt), &opt) ||
433 nla_put_u32(skb, TCA_RED_MAX_P, q->parms.max_P) ||
434 nla_put_bitfield32(skb, TCA_RED_FLAGS,
435 q->flags, TC_RED_SUPPORTED_FLAGS) ||
436 tcf_qevent_dump(skb, TCA_RED_MARK_BLOCK, &q->qe_mark) ||
437 tcf_qevent_dump(skb, TCA_RED_EARLY_DROP_BLOCK, &q->qe_early_drop))
438 goto nla_put_failure;
439 return nla_nest_end(skb, opts);
440
441 nla_put_failure:
442 nla_nest_cancel(skb, opts);
443 return -EMSGSIZE;
444 }
445
446 static int red_dump_stats(struct Qdisc *sch, struct gnet_dump *d)
447 {
448 struct red_sched_data *q = qdisc_priv(sch);
449 struct net_device *dev = qdisc_dev(sch);
450 struct tc_red_xstats st = {0};
451
452 if (sch->flags & TCQ_F_OFFLOADED) {
453 struct tc_red_qopt_offload hw_stats_request = {
454 .command = TC_RED_XSTATS,
455 .handle = sch->handle,
456 .parent = sch->parent,
457 {
458 .xstats = &q->stats,
459 },
460 };
461 dev->netdev_ops->ndo_setup_tc(dev, TC_SETUP_QDISC_RED,
462 &hw_stats_request);
463 }
464 st.early = q->stats.prob_drop + q->stats.forced_drop;
465 st.pdrop = q->stats.pdrop;
466 st.marked = q->stats.prob_mark + q->stats.forced_mark;
467
468 return gnet_stats_copy_app(d, &st, sizeof(st));
469 }
470
471 static int red_dump_class(struct Qdisc *sch, unsigned long cl,
472 struct sk_buff *skb, struct tcmsg *tcm)
473 {
474 struct red_sched_data *q = qdisc_priv(sch);
475
476 tcm->tcm_handle |= TC_H_MIN(1);
477 tcm->tcm_info = q->qdisc->handle;
478 return 0;
479 }
480
481 static void red_graft_offload(struct Qdisc *sch,
482 struct Qdisc *new, struct Qdisc *old,
483 struct netlink_ext_ack *extack)
484 {
485 struct tc_red_qopt_offload graft_offload = {
486 .handle = sch->handle,
487 .parent = sch->parent,
488 .child_handle = new->handle,
489 .command = TC_RED_GRAFT,
490 };
491
492 qdisc_offload_graft_helper(qdisc_dev(sch), sch, new, old,
493 TC_SETUP_QDISC_RED, &graft_offload, extack);
494 }
495
496 static int red_graft(struct Qdisc *sch, unsigned long arg, struct Qdisc *new,
497 struct Qdisc **old, struct netlink_ext_ack *extack)
498 {
499 struct red_sched_data *q = qdisc_priv(sch);
500
501 if (new == NULL)
502 new = &noop_qdisc;
503
504 *old = qdisc_replace(sch, new, &q->qdisc);
505
506 red_graft_offload(sch, new, *old, extack);
507 return 0;
508 }
509
510 static struct Qdisc *red_leaf(struct Qdisc *sch, unsigned long arg)
511 {
512 struct red_sched_data *q = qdisc_priv(sch);
513 return q->qdisc;
514 }
515
516 static unsigned long red_find(struct Qdisc *sch, u32 classid)
517 {
518 return 1;
519 }
520
521 static void red_walk(struct Qdisc *sch, struct qdisc_walker *walker)
522 {
523 if (!walker->stop) {
524 tc_qdisc_stats_dump(sch, 1, walker);
525 }
526 }
527
528 static const struct Qdisc_class_ops red_class_ops = {
529 .graft = red_graft,
530 .leaf = red_leaf,
531 .find = red_find,
532 .walk = red_walk,
533 .dump = red_dump_class,
534 };
535
536 static struct Qdisc_ops red_qdisc_ops __read_mostly = {
537 .id = "red",
538 .priv_size = sizeof(struct red_sched_data),
539 .cl_ops = &red_class_ops,
540 .enqueue = red_enqueue,
541 .dequeue = red_dequeue,
542 .peek = red_peek,
543 .init = red_init,
544 .reset = red_reset,
545 .destroy = red_destroy,
546 .change = red_change,
547 .dump = red_dump,
548 .dump_stats = red_dump_stats,
549 .owner = THIS_MODULE,
550 };
551 MODULE_ALIAS_NET_SCH("red");
552
553 static int __init red_module_init(void)
554 {
555 return register_qdisc(&red_qdisc_ops);
556 }
557
558 static void __exit red_module_exit(void)
559 {
560 unregister_qdisc(&red_qdisc_ops);
561 }
562
563 module_init(red_module_init)
564 module_exit(red_module_exit)
565
566 MODULE_LICENSE("GPL");
567 MODULE_DESCRIPTION("Random Early Detection qdisc");
568
Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.