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45e14433 | 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> | |
cdfb74d4 | 17 | #include <linux/vmalloc.h> |
45e14433 | 18 | #include <net/pkt_sched.h> |
19 | #include <net/inet_ecn.h> | |
20 | #include <net/red.h> | |
1bd758eb | 21 | #include <net/flow_dissector.h> |
45e14433 | 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 | ||
51 | struct choke_sched_data { | |
52 | /* Parameters */ | |
53 | u32 limit; | |
54 | unsigned char flags; | |
55 | ||
56 | struct red_parms parms; | |
57 | ||
58 | /* Variables */ | |
eeca6688 | 59 | struct red_vars vars; |
25d8c0d5 | 60 | struct tcf_proto __rcu *filter_list; |
45e14433 | 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 | ||
45e14433 | 79 | /* number of elements in queue including holes */ |
80 | static 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 */ | |
86 | static 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) */ | |
92 | static 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 */ | |
98 | static 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 */ | |
108 | static 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" */ | |
118 | static 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 | ||
25331d6c | 130 | qdisc_qstats_backlog_dec(sch, skb); |
2ccccf5f | 131 | qdisc_tree_reduce_backlog(sch, 1, qdisc_pkt_len(skb)); |
45e14433 | 132 | qdisc_drop(skb, sch); |
45e14433 | 133 | --sch->q.qlen; |
134 | } | |
135 | ||
26f70e12 | 136 | struct choke_skb_cb { |
2bcc34bb ED |
137 | u16 classid; |
138 | u8 keys_valid; | |
2e99403d | 139 | struct flow_keys_digest keys; |
26f70e12 ED |
140 | }; |
141 | ||
142 | static inline struct choke_skb_cb *choke_skb_cb(const struct sk_buff *skb) | |
143 | { | |
16bda13d | 144 | qdisc_cb_private_validate(skb, sizeof(struct choke_skb_cb)); |
26f70e12 ED |
145 | return (struct choke_skb_cb *)qdisc_skb_cb(skb)->data; |
146 | } | |
147 | ||
45e14433 | 148 | static inline void choke_set_classid(struct sk_buff *skb, u16 classid) |
149 | { | |
26f70e12 | 150 | choke_skb_cb(skb)->classid = classid; |
45e14433 | 151 | } |
152 | ||
153 | static u16 choke_get_classid(const struct sk_buff *skb) | |
154 | { | |
26f70e12 | 155 | return choke_skb_cb(skb)->classid; |
45e14433 | 156 | } |
157 | ||
2bcc34bb ED |
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 | */ | |
163 | static bool choke_match_flow(struct sk_buff *skb1, | |
164 | struct sk_buff *skb2) | |
165 | { | |
25711786 ED |
166 | struct flow_keys temp; |
167 | ||
2bcc34bb ED |
168 | if (skb1->protocol != skb2->protocol) |
169 | return false; | |
170 | ||
171 | if (!choke_skb_cb(skb1)->keys_valid) { | |
172 | choke_skb_cb(skb1)->keys_valid = 1; | |
cd79a238 | 173 | skb_flow_dissect_flow_keys(skb1, &temp, 0); |
2e99403d | 174 | make_flow_keys_digest(&choke_skb_cb(skb1)->keys, &temp); |
2bcc34bb ED |
175 | } |
176 | ||
177 | if (!choke_skb_cb(skb2)->keys_valid) { | |
178 | choke_skb_cb(skb2)->keys_valid = 1; | |
cd79a238 | 179 | skb_flow_dissect_flow_keys(skb2, &temp, 0); |
2e99403d | 180 | make_flow_keys_digest(&choke_skb_cb(skb2)->keys, &temp); |
2bcc34bb ED |
181 | } |
182 | ||
183 | return !memcmp(&choke_skb_cb(skb1)->keys, | |
184 | &choke_skb_cb(skb2)->keys, | |
2e99403d | 185 | sizeof(choke_skb_cb(skb1)->keys)); |
2bcc34bb ED |
186 | } |
187 | ||
45e14433 | 188 | /* |
189 | * Classify flow using either: | |
190 | * 1. pre-existing classification result in skb | |
191 | * 2. fast internal classification | |
192 | * 3. use TC filter based classification | |
193 | */ | |
194 | static bool choke_classify(struct sk_buff *skb, | |
195 | struct Qdisc *sch, int *qerr) | |
196 | ||
197 | { | |
198 | struct choke_sched_data *q = qdisc_priv(sch); | |
199 | struct tcf_result res; | |
25d8c0d5 | 200 | struct tcf_proto *fl; |
45e14433 | 201 | int result; |
202 | ||
25d8c0d5 | 203 | fl = rcu_dereference_bh(q->filter_list); |
3b3ae880 | 204 | result = tc_classify(skb, fl, &res, false); |
45e14433 | 205 | if (result >= 0) { |
206 | #ifdef CONFIG_NET_CLS_ACT | |
207 | switch (result) { | |
208 | case TC_ACT_STOLEN: | |
209 | case TC_ACT_QUEUED: | |
210 | *qerr = NET_XMIT_SUCCESS | __NET_XMIT_STOLEN; | |
211 | case TC_ACT_SHOT: | |
212 | return false; | |
213 | } | |
214 | #endif | |
215 | choke_set_classid(skb, TC_H_MIN(res.classid)); | |
216 | return true; | |
217 | } | |
218 | ||
219 | return false; | |
220 | } | |
221 | ||
222 | /* | |
223 | * Select a packet at random from queue | |
224 | * HACK: since queue can have holes from previous deletion; retry several | |
225 | * times to find a random skb but then just give up and return the head | |
226 | * Will return NULL if queue is empty (q->head == q->tail) | |
227 | */ | |
228 | static struct sk_buff *choke_peek_random(const struct choke_sched_data *q, | |
229 | unsigned int *pidx) | |
230 | { | |
231 | struct sk_buff *skb; | |
232 | int retrys = 3; | |
233 | ||
234 | do { | |
f337db64 | 235 | *pidx = (q->head + prandom_u32_max(choke_len(q))) & q->tab_mask; |
45e14433 | 236 | skb = q->tab[*pidx]; |
237 | if (skb) | |
238 | return skb; | |
239 | } while (--retrys > 0); | |
240 | ||
241 | return q->tab[*pidx = q->head]; | |
242 | } | |
243 | ||
244 | /* | |
245 | * Compare new packet with random packet in queue | |
246 | * returns true if matched and sets *pidx | |
247 | */ | |
248 | static bool choke_match_random(const struct choke_sched_data *q, | |
249 | struct sk_buff *nskb, | |
250 | unsigned int *pidx) | |
251 | { | |
252 | struct sk_buff *oskb; | |
253 | ||
254 | if (q->head == q->tail) | |
255 | return false; | |
256 | ||
257 | oskb = choke_peek_random(q, pidx); | |
25d8c0d5 | 258 | if (rcu_access_pointer(q->filter_list)) |
45e14433 | 259 | return choke_get_classid(nskb) == choke_get_classid(oskb); |
260 | ||
261 | return choke_match_flow(oskb, nskb); | |
262 | } | |
263 | ||
264 | static int choke_enqueue(struct sk_buff *skb, struct Qdisc *sch) | |
265 | { | |
25d8c0d5 | 266 | int ret = NET_XMIT_SUCCESS | __NET_XMIT_BYPASS; |
45e14433 | 267 | struct choke_sched_data *q = qdisc_priv(sch); |
eeca6688 | 268 | const struct red_parms *p = &q->parms; |
45e14433 | 269 | |
25d8c0d5 | 270 | if (rcu_access_pointer(q->filter_list)) { |
45e14433 | 271 | /* If using external classifiers, get result and record it. */ |
272 | if (!choke_classify(skb, sch, &ret)) | |
273 | goto other_drop; /* Packet was eaten by filter */ | |
274 | } | |
275 | ||
2bcc34bb | 276 | choke_skb_cb(skb)->keys_valid = 0; |
45e14433 | 277 | /* Compute average queue usage (see RED) */ |
eeca6688 ED |
278 | q->vars.qavg = red_calc_qavg(p, &q->vars, sch->q.qlen); |
279 | if (red_is_idling(&q->vars)) | |
280 | red_end_of_idle_period(&q->vars); | |
45e14433 | 281 | |
282 | /* Is queue small? */ | |
eeca6688 ED |
283 | if (q->vars.qavg <= p->qth_min) |
284 | q->vars.qcount = -1; | |
45e14433 | 285 | else { |
286 | unsigned int idx; | |
287 | ||
288 | /* Draw a packet at random from queue and compare flow */ | |
289 | if (choke_match_random(q, skb, &idx)) { | |
290 | q->stats.matched++; | |
291 | choke_drop_by_idx(sch, idx); | |
292 | goto congestion_drop; | |
293 | } | |
294 | ||
295 | /* Queue is large, always mark/drop */ | |
eeca6688 ED |
296 | if (q->vars.qavg > p->qth_max) { |
297 | q->vars.qcount = -1; | |
45e14433 | 298 | |
25331d6c | 299 | qdisc_qstats_overlimit(sch); |
45e14433 | 300 | if (use_harddrop(q) || !use_ecn(q) || |
301 | !INET_ECN_set_ce(skb)) { | |
302 | q->stats.forced_drop++; | |
303 | goto congestion_drop; | |
304 | } | |
305 | ||
306 | q->stats.forced_mark++; | |
eeca6688 ED |
307 | } else if (++q->vars.qcount) { |
308 | if (red_mark_probability(p, &q->vars, q->vars.qavg)) { | |
309 | q->vars.qcount = 0; | |
310 | q->vars.qR = red_random(p); | |
45e14433 | 311 | |
25331d6c | 312 | qdisc_qstats_overlimit(sch); |
45e14433 | 313 | if (!use_ecn(q) || !INET_ECN_set_ce(skb)) { |
314 | q->stats.prob_drop++; | |
315 | goto congestion_drop; | |
316 | } | |
317 | ||
318 | q->stats.prob_mark++; | |
319 | } | |
320 | } else | |
eeca6688 | 321 | q->vars.qR = red_random(p); |
45e14433 | 322 | } |
323 | ||
324 | /* Admit new packet */ | |
325 | if (sch->q.qlen < q->limit) { | |
326 | q->tab[q->tail] = skb; | |
327 | q->tail = (q->tail + 1) & q->tab_mask; | |
328 | ++sch->q.qlen; | |
25331d6c | 329 | qdisc_qstats_backlog_inc(sch, skb); |
45e14433 | 330 | return NET_XMIT_SUCCESS; |
331 | } | |
332 | ||
333 | q->stats.pdrop++; | |
17045755 | 334 | return qdisc_drop(skb, sch); |
45e14433 | 335 | |
17045755 | 336 | congestion_drop: |
45e14433 | 337 | qdisc_drop(skb, sch); |
338 | return NET_XMIT_CN; | |
339 | ||
17045755 | 340 | other_drop: |
45e14433 | 341 | if (ret & __NET_XMIT_BYPASS) |
25331d6c | 342 | qdisc_qstats_drop(sch); |
45e14433 | 343 | kfree_skb(skb); |
344 | return ret; | |
345 | } | |
346 | ||
347 | static struct sk_buff *choke_dequeue(struct Qdisc *sch) | |
348 | { | |
349 | struct choke_sched_data *q = qdisc_priv(sch); | |
350 | struct sk_buff *skb; | |
351 | ||
352 | if (q->head == q->tail) { | |
eeca6688 ED |
353 | if (!red_is_idling(&q->vars)) |
354 | red_start_of_idle_period(&q->vars); | |
45e14433 | 355 | return NULL; |
356 | } | |
357 | ||
358 | skb = q->tab[q->head]; | |
359 | q->tab[q->head] = NULL; | |
360 | choke_zap_head_holes(q); | |
361 | --sch->q.qlen; | |
25331d6c | 362 | qdisc_qstats_backlog_dec(sch, skb); |
45e14433 | 363 | qdisc_bstats_update(sch, skb); |
364 | ||
365 | return skb; | |
366 | } | |
367 | ||
45e14433 | 368 | static void choke_reset(struct Qdisc *sch) |
369 | { | |
370 | struct choke_sched_data *q = qdisc_priv(sch); | |
371 | ||
77e62da6 WC |
372 | while (q->head != q->tail) { |
373 | struct sk_buff *skb = q->tab[q->head]; | |
374 | ||
375 | q->head = (q->head + 1) & q->tab_mask; | |
376 | if (!skb) | |
377 | continue; | |
378 | qdisc_qstats_backlog_dec(sch, skb); | |
379 | --sch->q.qlen; | |
380 | qdisc_drop(skb, sch); | |
381 | } | |
382 | ||
383 | memset(q->tab, 0, (q->tab_mask + 1) * sizeof(struct sk_buff *)); | |
384 | q->head = q->tail = 0; | |
eeca6688 | 385 | red_restart(&q->vars); |
45e14433 | 386 | } |
387 | ||
388 | static const struct nla_policy choke_policy[TCA_CHOKE_MAX + 1] = { | |
389 | [TCA_CHOKE_PARMS] = { .len = sizeof(struct tc_red_qopt) }, | |
390 | [TCA_CHOKE_STAB] = { .len = RED_STAB_SIZE }, | |
a73ed26b | 391 | [TCA_CHOKE_MAX_P] = { .type = NLA_U32 }, |
45e14433 | 392 | }; |
393 | ||
394 | ||
395 | static void choke_free(void *addr) | |
396 | { | |
4cb28970 | 397 | kvfree(addr); |
45e14433 | 398 | } |
399 | ||
400 | static int choke_change(struct Qdisc *sch, struct nlattr *opt) | |
401 | { | |
402 | struct choke_sched_data *q = qdisc_priv(sch); | |
403 | struct nlattr *tb[TCA_CHOKE_MAX + 1]; | |
404 | const struct tc_red_qopt *ctl; | |
405 | int err; | |
406 | struct sk_buff **old = NULL; | |
407 | unsigned int mask; | |
a73ed26b | 408 | u32 max_P; |
45e14433 | 409 | |
410 | if (opt == NULL) | |
411 | return -EINVAL; | |
412 | ||
413 | err = nla_parse_nested(tb, TCA_CHOKE_MAX, opt, choke_policy); | |
414 | if (err < 0) | |
415 | return err; | |
416 | ||
417 | if (tb[TCA_CHOKE_PARMS] == NULL || | |
418 | tb[TCA_CHOKE_STAB] == NULL) | |
419 | return -EINVAL; | |
420 | ||
a73ed26b ED |
421 | max_P = tb[TCA_CHOKE_MAX_P] ? nla_get_u32(tb[TCA_CHOKE_MAX_P]) : 0; |
422 | ||
45e14433 | 423 | ctl = nla_data(tb[TCA_CHOKE_PARMS]); |
424 | ||
425 | if (ctl->limit > CHOKE_MAX_QUEUE) | |
426 | return -EINVAL; | |
427 | ||
428 | mask = roundup_pow_of_two(ctl->limit + 1) - 1; | |
429 | if (mask != q->tab_mask) { | |
430 | struct sk_buff **ntab; | |
431 | ||
8be04b93 JP |
432 | ntab = kcalloc(mask + 1, sizeof(struct sk_buff *), |
433 | GFP_KERNEL | __GFP_NOWARN); | |
45e14433 | 434 | if (!ntab) |
435 | ntab = vzalloc((mask + 1) * sizeof(struct sk_buff *)); | |
436 | if (!ntab) | |
437 | return -ENOMEM; | |
438 | ||
439 | sch_tree_lock(sch); | |
440 | old = q->tab; | |
441 | if (old) { | |
442 | unsigned int oqlen = sch->q.qlen, tail = 0; | |
2ccccf5f | 443 | unsigned dropped = 0; |
45e14433 | 444 | |
445 | while (q->head != q->tail) { | |
446 | struct sk_buff *skb = q->tab[q->head]; | |
447 | ||
448 | q->head = (q->head + 1) & q->tab_mask; | |
449 | if (!skb) | |
450 | continue; | |
451 | if (tail < mask) { | |
452 | ntab[tail++] = skb; | |
453 | continue; | |
454 | } | |
2ccccf5f | 455 | dropped += qdisc_pkt_len(skb); |
25331d6c | 456 | qdisc_qstats_backlog_dec(sch, skb); |
45e14433 | 457 | --sch->q.qlen; |
458 | qdisc_drop(skb, sch); | |
459 | } | |
2ccccf5f | 460 | qdisc_tree_reduce_backlog(sch, oqlen - sch->q.qlen, dropped); |
45e14433 | 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, | |
a73ed26b ED |
475 | nla_data(tb[TCA_CHOKE_STAB]), |
476 | max_P); | |
eeca6688 | 477 | red_set_vars(&q->vars); |
45e14433 | 478 | |
479 | if (q->head == q->tail) | |
eeca6688 | 480 | red_end_of_idle_period(&q->vars); |
45e14433 | 481 | |
482 | sch_tree_unlock(sch); | |
483 | choke_free(old); | |
484 | return 0; | |
485 | } | |
486 | ||
487 | static int choke_init(struct Qdisc *sch, struct nlattr *opt) | |
488 | { | |
489 | return choke_change(sch, opt); | |
490 | } | |
491 | ||
492 | static 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 | ||
1b34ec43 DM |
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; | |
45e14433 | 513 | return nla_nest_end(skb, opts); |
514 | ||
515 | nla_put_failure: | |
516 | nla_nest_cancel(skb, opts); | |
517 | return -EMSGSIZE; | |
518 | } | |
519 | ||
520 | static 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 | ||
534 | static 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 | ||
45e14433 | 542 | static struct sk_buff *choke_peek_head(struct Qdisc *sch) |
543 | { | |
544 | struct choke_sched_data *q = qdisc_priv(sch); | |
545 | ||
546 | return (q->head != q->tail) ? q->tab[q->head] : NULL; | |
547 | } | |
548 | ||
549 | static struct Qdisc_ops choke_qdisc_ops __read_mostly = { | |
550 | .id = "choke", | |
551 | .priv_size = sizeof(struct choke_sched_data), | |
552 | ||
553 | .enqueue = choke_enqueue, | |
554 | .dequeue = choke_dequeue, | |
555 | .peek = choke_peek_head, | |
45e14433 | 556 | .init = choke_init, |
557 | .destroy = choke_destroy, | |
558 | .reset = choke_reset, | |
559 | .change = choke_change, | |
560 | .dump = choke_dump, | |
561 | .dump_stats = choke_dump_stats, | |
562 | .owner = THIS_MODULE, | |
563 | }; | |
564 | ||
565 | static int __init choke_module_init(void) | |
566 | { | |
567 | return register_qdisc(&choke_qdisc_ops); | |
568 | } | |
569 | ||
570 | static void __exit choke_module_exit(void) | |
571 | { | |
572 | unregister_qdisc(&choke_qdisc_ops); | |
573 | } | |
574 | ||
575 | module_init(choke_module_init) | |
576 | module_exit(choke_module_exit) | |
577 | ||
578 | MODULE_LICENSE("GPL"); |