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(p: &q->parms, |
79 | v: &q->vars, |
80 | backlog: child->qstats.backlog); |
81 | |
82 | if (red_is_idling(v: &q->vars)) |
83 | red_end_of_idle_period(v: &q->vars); |
84 | |
85 | switch (red_action(p: &q->parms, v: &q->vars, qavg: 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(qe: &q->qe_mark, sch, skb, to_free, ret: &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(qe: &q->qe_mark, sch, skb, to_free, ret: &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, sch: 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(qe: &q->qe_early_drop, sch, skb, to_free, ret: &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(v: &q->vars)) |
163 | red_start_of_idle_period(v: &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(qdisc: q->qdisc); |
181 | red_restart(v: &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(qdisc: 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(qe: &q->qe_mark, sch); |
218 | tcf_qevent_destroy(qe: &q->qe_early_drop, sch); |
219 | del_timer_sync(timer: &q->adapt_timer); |
220 | red_offload(sch, enable: false); |
221 | qdisc_put(qdisc: 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(nla: tb[TCA_RED_MAX_P]) : 0; |
252 | |
253 | ctl = nla_data(nla: tb[TCA_RED_PARMS]); |
254 | stab = nla_data(nla: tb[TCA_RED_STAB]); |
255 | if (!red_check_params(qth_min: ctl->qth_min, qth_max: ctl->qth_max, Wlog: ctl->Wlog, |
256 | Scell_log: ctl->Scell_log, stab)) |
257 | return -EINVAL; |
258 | |
259 | err = red_get_flags(qopt_flags: ctl->flags, TC_RED_HISTORIC_FLAGS, |
260 | flags_attr: tb[TCA_RED_FLAGS], TC_RED_SUPPORTED_FLAGS, |
261 | p_flags: &flags_bf, p_userbits: &userbits, extack); |
262 | if (err) |
263 | return err; |
264 | |
265 | if (ctl->limit > 0) { |
266 | child = fifo_create_dflt(sch, ops: &bfifo_qdisc_ops, limit: ctl->limit, |
267 | extack); |
268 | if (IS_ERR(ptr: child)) |
269 | return PTR_ERR(ptr: child); |
270 | |
271 | /* child is fifo, no need to check for noop_qdisc */ |
272 | qdisc_hash_add(q: child, invisible: true); |
273 | } |
274 | |
275 | sch_tree_lock(q: 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(sch: q->qdisc); |
287 | old_child = q->qdisc; |
288 | q->qdisc = child; |
289 | } |
290 | |
291 | red_set_parms(p: &q->parms, |
292 | qth_min: ctl->qth_min, qth_max: ctl->qth_max, Wlog: ctl->Wlog, |
293 | Plog: ctl->Plog, Scell_log: ctl->Scell_log, |
294 | stab, |
295 | max_P); |
296 | red_set_vars(v: &q->vars); |
297 | |
298 | del_timer(timer: &q->adapt_timer); |
299 | if (ctl->flags & TC_RED_ADAPTATIVE) |
300 | mod_timer(timer: &q->adapt_timer, expires: jiffies + HZ/2); |
301 | |
302 | if (!q->qdisc->q.qlen) |
303 | red_start_of_idle_period(v: &q->vars); |
304 | |
305 | sch_tree_unlock(q: sch); |
306 | |
307 | red_offload(sch, enable: true); |
308 | |
309 | if (old_child) |
310 | qdisc_put(qdisc: old_child); |
311 | return 0; |
312 | |
313 | unlock_out: |
314 | sch_tree_unlock(q: sch); |
315 | if (child) |
316 | qdisc_put(qdisc: 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: qdisc_root_sleeping(qdisc: sch)); |
328 | spin_lock(lock: root_lock); |
329 | red_adaptative_algo(p: &q->parms, v: &q->vars); |
330 | mod_timer(timer: &q->adapt_timer, expires: jiffies + HZ/2); |
331 | spin_unlock(lock: 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, nla: opt, policy: 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(qe: &q->qe_early_drop, sch, |
359 | binder_type: FLOW_BLOCK_BINDER_TYPE_RED_EARLY_DROP, |
360 | block_index_attr: tb[TCA_RED_EARLY_DROP_BLOCK], extack); |
361 | if (err) |
362 | return err; |
363 | |
364 | return tcf_qevent_init(qe: &q->qe_mark, sch, |
365 | binder_type: FLOW_BLOCK_BINDER_TYPE_RED_MARK, |
366 | block_index_attr: 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, nla: opt, policy: red_policy, |
377 | extack); |
378 | if (err < 0) |
379 | return err; |
380 | |
381 | err = tcf_qevent_validate_change(qe: &q->qe_early_drop, |
382 | block_index_attr: tb[TCA_RED_EARLY_DROP_BLOCK], extack); |
383 | if (err) |
384 | return err; |
385 | |
386 | err = tcf_qevent_validate_change(qe: &q->qe_mark, |
387 | block_index_attr: 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(q: sch, type: TC_SETUP_QDISC_RED, type_data: &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, attrtype: TCA_OPTIONS); |
430 | if (opts == NULL) |
431 | goto nla_put_failure; |
432 | if (nla_put(skb, attrtype: TCA_RED_PARMS, attrlen: sizeof(opt), data: &opt) || |
433 | nla_put_u32(skb, attrtype: TCA_RED_MAX_P, value: q->parms.max_P) || |
434 | nla_put_bitfield32(skb, attrtype: TCA_RED_FLAGS, |
435 | value: q->flags, TC_RED_SUPPORTED_FLAGS) || |
436 | tcf_qevent_dump(skb, attr_name: TCA_RED_MARK_BLOCK, qe: &q->qe_mark) || |
437 | tcf_qevent_dump(skb, attr_name: TCA_RED_EARLY_DROP_BLOCK, qe: &q->qe_early_drop)) |
438 | goto nla_put_failure; |
439 | return nla_nest_end(skb, start: opts); |
440 | |
441 | nla_put_failure: |
442 | nla_nest_cancel(skb, start: 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(qdisc: 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: &st, len: 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(dev: qdisc_dev(qdisc: sch), sch, new, old, |
493 | type: TC_SETUP_QDISC_RED, type_data: &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, pold: &q->qdisc); |
505 | |
506 | red_graft_offload(sch, new, old: *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, cl: 1, arg: 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 | |
552 | static int __init red_module_init(void) |
553 | { |
554 | return register_qdisc(qops: &red_qdisc_ops); |
555 | } |
556 | |
557 | static void __exit red_module_exit(void) |
558 | { |
559 | unregister_qdisc(qops: &red_qdisc_ops); |
560 | } |
561 | |
562 | module_init(red_module_init) |
563 | module_exit(red_module_exit) |
564 | |
565 | MODULE_LICENSE("GPL" ); |
566 | |