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TOMOYO Linux Cross Reference
Linux/net/sched/sch_fq_codel.c

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  1 /*
  2  * Fair Queue CoDel discipline
  3  *
  4  *      This program is free software; you can redistribute it and/or
  5  *      modify it under the terms of the GNU General Public License
  6  *      as published by the Free Software Foundation; either version
  7  *      2 of the License, or (at your option) any later version.
  8  *
  9  *  Copyright (C) 2012,2015 Eric Dumazet <edumazet@google.com>
 10  */
 11 
 12 #include <linux/module.h>
 13 #include <linux/types.h>
 14 #include <linux/kernel.h>
 15 #include <linux/jiffies.h>
 16 #include <linux/string.h>
 17 #include <linux/in.h>
 18 #include <linux/errno.h>
 19 #include <linux/init.h>
 20 #include <linux/skbuff.h>
 21 #include <linux/jhash.h>
 22 #include <linux/slab.h>
 23 #include <linux/vmalloc.h>
 24 #include <net/netlink.h>
 25 #include <net/pkt_sched.h>
 26 #include <net/pkt_cls.h>
 27 #include <net/codel.h>
 28 #include <net/codel_impl.h>
 29 #include <net/codel_qdisc.h>
 30 
 31 /*      Fair Queue CoDel.
 32  *
 33  * Principles :
 34  * Packets are classified (internal classifier or external) on flows.
 35  * This is a Stochastic model (as we use a hash, several flows
 36  *                             might be hashed on same slot)
 37  * Each flow has a CoDel managed queue.
 38  * Flows are linked onto two (Round Robin) lists,
 39  * so that new flows have priority on old ones.
 40  *
 41  * For a given flow, packets are not reordered (CoDel uses a FIFO)
 42  * head drops only.
 43  * ECN capability is on by default.
 44  * Low memory footprint (64 bytes per flow)
 45  */
 46 
 47 struct fq_codel_flow {
 48         struct sk_buff    *head;
 49         struct sk_buff    *tail;
 50         struct list_head  flowchain;
 51         int               deficit;
 52         u32               dropped; /* number of drops (or ECN marks) on this flow */
 53         struct codel_vars cvars;
 54 }; /* please try to keep this structure <= 64 bytes */
 55 
 56 struct fq_codel_sched_data {
 57         struct tcf_proto __rcu *filter_list; /* optional external classifier */
 58         struct tcf_block *block;
 59         struct fq_codel_flow *flows;    /* Flows table [flows_cnt] */
 60         u32             *backlogs;      /* backlog table [flows_cnt] */
 61         u32             flows_cnt;      /* number of flows */
 62         u32             quantum;        /* psched_mtu(qdisc_dev(sch)); */
 63         u32             drop_batch_size;
 64         u32             memory_limit;
 65         struct codel_params cparams;
 66         struct codel_stats cstats;
 67         u32             memory_usage;
 68         u32             drop_overmemory;
 69         u32             drop_overlimit;
 70         u32             new_flow_count;
 71 
 72         struct list_head new_flows;     /* list of new flows */
 73         struct list_head old_flows;     /* list of old flows */
 74 };
 75 
 76 static unsigned int fq_codel_hash(const struct fq_codel_sched_data *q,
 77                                   struct sk_buff *skb)
 78 {
 79         return reciprocal_scale(skb_get_hash(skb), q->flows_cnt);
 80 }
 81 
 82 static unsigned int fq_codel_classify(struct sk_buff *skb, struct Qdisc *sch,
 83                                       int *qerr)
 84 {
 85         struct fq_codel_sched_data *q = qdisc_priv(sch);
 86         struct tcf_proto *filter;
 87         struct tcf_result res;
 88         int result;
 89 
 90         if (TC_H_MAJ(skb->priority) == sch->handle &&
 91             TC_H_MIN(skb->priority) > 0 &&
 92             TC_H_MIN(skb->priority) <= q->flows_cnt)
 93                 return TC_H_MIN(skb->priority);
 94 
 95         filter = rcu_dereference_bh(q->filter_list);
 96         if (!filter)
 97                 return fq_codel_hash(q, skb) + 1;
 98 
 99         *qerr = NET_XMIT_SUCCESS | __NET_XMIT_BYPASS;
100         result = tcf_classify(skb, filter, &res, false);
101         if (result >= 0) {
102 #ifdef CONFIG_NET_CLS_ACT
103                 switch (result) {
104                 case TC_ACT_STOLEN:
105                 case TC_ACT_QUEUED:
106                 case TC_ACT_TRAP:
107                         *qerr = NET_XMIT_SUCCESS | __NET_XMIT_STOLEN;
108                         /* fall through */
109                 case TC_ACT_SHOT:
110                         return 0;
111                 }
112 #endif
113                 if (TC_H_MIN(res.classid) <= q->flows_cnt)
114                         return TC_H_MIN(res.classid);
115         }
116         return 0;
117 }
118 
119 /* helper functions : might be changed when/if skb use a standard list_head */
120 
121 /* remove one skb from head of slot queue */
122 static inline struct sk_buff *dequeue_head(struct fq_codel_flow *flow)
123 {
124         struct sk_buff *skb = flow->head;
125 
126         flow->head = skb->next;
127         skb_mark_not_on_list(skb);
128         return skb;
129 }
130 
131 /* add skb to flow queue (tail add) */
132 static inline void flow_queue_add(struct fq_codel_flow *flow,
133                                   struct sk_buff *skb)
134 {
135         if (flow->head == NULL)
136                 flow->head = skb;
137         else
138                 flow->tail->next = skb;
139         flow->tail = skb;
140         skb->next = NULL;
141 }
142 
143 static unsigned int fq_codel_drop(struct Qdisc *sch, unsigned int max_packets,
144                                   struct sk_buff **to_free)
145 {
146         struct fq_codel_sched_data *q = qdisc_priv(sch);
147         struct sk_buff *skb;
148         unsigned int maxbacklog = 0, idx = 0, i, len;
149         struct fq_codel_flow *flow;
150         unsigned int threshold;
151         unsigned int mem = 0;
152 
153         /* Queue is full! Find the fat flow and drop packet(s) from it.
154          * This might sound expensive, but with 1024 flows, we scan
155          * 4KB of memory, and we dont need to handle a complex tree
156          * in fast path (packet queue/enqueue) with many cache misses.
157          * In stress mode, we'll try to drop 64 packets from the flow,
158          * amortizing this linear lookup to one cache line per drop.
159          */
160         for (i = 0; i < q->flows_cnt; i++) {
161                 if (q->backlogs[i] > maxbacklog) {
162                         maxbacklog = q->backlogs[i];
163                         idx = i;
164                 }
165         }
166 
167         /* Our goal is to drop half of this fat flow backlog */
168         threshold = maxbacklog >> 1;
169 
170         flow = &q->flows[idx];
171         len = 0;
172         i = 0;
173         do {
174                 skb = dequeue_head(flow);
175                 len += qdisc_pkt_len(skb);
176                 mem += get_codel_cb(skb)->mem_usage;
177                 __qdisc_drop(skb, to_free);
178         } while (++i < max_packets && len < threshold);
179 
180         flow->dropped += i;
181         q->backlogs[idx] -= len;
182         q->memory_usage -= mem;
183         sch->qstats.drops += i;
184         sch->qstats.backlog -= len;
185         sch->q.qlen -= i;
186         return idx;
187 }
188 
189 static int fq_codel_enqueue(struct sk_buff *skb, struct Qdisc *sch,
190                             struct sk_buff **to_free)
191 {
192         struct fq_codel_sched_data *q = qdisc_priv(sch);
193         unsigned int idx, prev_backlog, prev_qlen;
194         struct fq_codel_flow *flow;
195         int uninitialized_var(ret);
196         unsigned int pkt_len;
197         bool memory_limited;
198 
199         idx = fq_codel_classify(skb, sch, &ret);
200         if (idx == 0) {
201                 if (ret & __NET_XMIT_BYPASS)
202                         qdisc_qstats_drop(sch);
203                 __qdisc_drop(skb, to_free);
204                 return ret;
205         }
206         idx--;
207 
208         codel_set_enqueue_time(skb);
209         flow = &q->flows[idx];
210         flow_queue_add(flow, skb);
211         q->backlogs[idx] += qdisc_pkt_len(skb);
212         qdisc_qstats_backlog_inc(sch, skb);
213 
214         if (list_empty(&flow->flowchain)) {
215                 list_add_tail(&flow->flowchain, &q->new_flows);
216                 q->new_flow_count++;
217                 flow->deficit = q->quantum;
218                 flow->dropped = 0;
219         }
220         get_codel_cb(skb)->mem_usage = skb->truesize;
221         q->memory_usage += get_codel_cb(skb)->mem_usage;
222         memory_limited = q->memory_usage > q->memory_limit;
223         if (++sch->q.qlen <= sch->limit && !memory_limited)
224                 return NET_XMIT_SUCCESS;
225 
226         prev_backlog = sch->qstats.backlog;
227         prev_qlen = sch->q.qlen;
228 
229         /* save this packet length as it might be dropped by fq_codel_drop() */
230         pkt_len = qdisc_pkt_len(skb);
231         /* fq_codel_drop() is quite expensive, as it performs a linear search
232          * in q->backlogs[] to find a fat flow.
233          * So instead of dropping a single packet, drop half of its backlog
234          * with a 64 packets limit to not add a too big cpu spike here.
235          */
236         ret = fq_codel_drop(sch, q->drop_batch_size, to_free);
237 
238         prev_qlen -= sch->q.qlen;
239         prev_backlog -= sch->qstats.backlog;
240         q->drop_overlimit += prev_qlen;
241         if (memory_limited)
242                 q->drop_overmemory += prev_qlen;
243 
244         /* As we dropped packet(s), better let upper stack know this.
245          * If we dropped a packet for this flow, return NET_XMIT_CN,
246          * but in this case, our parents wont increase their backlogs.
247          */
248         if (ret == idx) {
249                 qdisc_tree_reduce_backlog(sch, prev_qlen - 1,
250                                           prev_backlog - pkt_len);
251                 return NET_XMIT_CN;
252         }
253         qdisc_tree_reduce_backlog(sch, prev_qlen, prev_backlog);
254         return NET_XMIT_SUCCESS;
255 }
256 
257 /* This is the specific function called from codel_dequeue()
258  * to dequeue a packet from queue. Note: backlog is handled in
259  * codel, we dont need to reduce it here.
260  */
261 static struct sk_buff *dequeue_func(struct codel_vars *vars, void *ctx)
262 {
263         struct Qdisc *sch = ctx;
264         struct fq_codel_sched_data *q = qdisc_priv(sch);
265         struct fq_codel_flow *flow;
266         struct sk_buff *skb = NULL;
267 
268         flow = container_of(vars, struct fq_codel_flow, cvars);
269         if (flow->head) {
270                 skb = dequeue_head(flow);
271                 q->backlogs[flow - q->flows] -= qdisc_pkt_len(skb);
272                 q->memory_usage -= get_codel_cb(skb)->mem_usage;
273                 sch->q.qlen--;
274                 sch->qstats.backlog -= qdisc_pkt_len(skb);
275         }
276         return skb;
277 }
278 
279 static void drop_func(struct sk_buff *skb, void *ctx)
280 {
281         struct Qdisc *sch = ctx;
282 
283         kfree_skb(skb);
284         qdisc_qstats_drop(sch);
285 }
286 
287 static struct sk_buff *fq_codel_dequeue(struct Qdisc *sch)
288 {
289         struct fq_codel_sched_data *q = qdisc_priv(sch);
290         struct sk_buff *skb;
291         struct fq_codel_flow *flow;
292         struct list_head *head;
293         u32 prev_drop_count, prev_ecn_mark;
294 
295 begin:
296         head = &q->new_flows;
297         if (list_empty(head)) {
298                 head = &q->old_flows;
299                 if (list_empty(head))
300                         return NULL;
301         }
302         flow = list_first_entry(head, struct fq_codel_flow, flowchain);
303 
304         if (flow->deficit <= 0) {
305                 flow->deficit += q->quantum;
306                 list_move_tail(&flow->flowchain, &q->old_flows);
307                 goto begin;
308         }
309 
310         prev_drop_count = q->cstats.drop_count;
311         prev_ecn_mark = q->cstats.ecn_mark;
312 
313         skb = codel_dequeue(sch, &sch->qstats.backlog, &q->cparams,
314                             &flow->cvars, &q->cstats, qdisc_pkt_len,
315                             codel_get_enqueue_time, drop_func, dequeue_func);
316 
317         flow->dropped += q->cstats.drop_count - prev_drop_count;
318         flow->dropped += q->cstats.ecn_mark - prev_ecn_mark;
319 
320         if (!skb) {
321                 /* force a pass through old_flows to prevent starvation */
322                 if ((head == &q->new_flows) && !list_empty(&q->old_flows))
323                         list_move_tail(&flow->flowchain, &q->old_flows);
324                 else
325                         list_del_init(&flow->flowchain);
326                 goto begin;
327         }
328         qdisc_bstats_update(sch, skb);
329         flow->deficit -= qdisc_pkt_len(skb);
330         /* We cant call qdisc_tree_reduce_backlog() if our qlen is 0,
331          * or HTB crashes. Defer it for next round.
332          */
333         if (q->cstats.drop_count && sch->q.qlen) {
334                 qdisc_tree_reduce_backlog(sch, q->cstats.drop_count,
335                                           q->cstats.drop_len);
336                 q->cstats.drop_count = 0;
337                 q->cstats.drop_len = 0;
338         }
339         return skb;
340 }
341 
342 static void fq_codel_flow_purge(struct fq_codel_flow *flow)
343 {
344         rtnl_kfree_skbs(flow->head, flow->tail);
345         flow->head = NULL;
346 }
347 
348 static void fq_codel_reset(struct Qdisc *sch)
349 {
350         struct fq_codel_sched_data *q = qdisc_priv(sch);
351         int i;
352 
353         INIT_LIST_HEAD(&q->new_flows);
354         INIT_LIST_HEAD(&q->old_flows);
355         for (i = 0; i < q->flows_cnt; i++) {
356                 struct fq_codel_flow *flow = q->flows + i;
357 
358                 fq_codel_flow_purge(flow);
359                 INIT_LIST_HEAD(&flow->flowchain);
360                 codel_vars_init(&flow->cvars);
361         }
362         memset(q->backlogs, 0, q->flows_cnt * sizeof(u32));
363         sch->q.qlen = 0;
364         sch->qstats.backlog = 0;
365         q->memory_usage = 0;
366 }
367 
368 static const struct nla_policy fq_codel_policy[TCA_FQ_CODEL_MAX + 1] = {
369         [TCA_FQ_CODEL_TARGET]   = { .type = NLA_U32 },
370         [TCA_FQ_CODEL_LIMIT]    = { .type = NLA_U32 },
371         [TCA_FQ_CODEL_INTERVAL] = { .type = NLA_U32 },
372         [TCA_FQ_CODEL_ECN]      = { .type = NLA_U32 },
373         [TCA_FQ_CODEL_FLOWS]    = { .type = NLA_U32 },
374         [TCA_FQ_CODEL_QUANTUM]  = { .type = NLA_U32 },
375         [TCA_FQ_CODEL_CE_THRESHOLD] = { .type = NLA_U32 },
376         [TCA_FQ_CODEL_DROP_BATCH_SIZE] = { .type = NLA_U32 },
377         [TCA_FQ_CODEL_MEMORY_LIMIT] = { .type = NLA_U32 },
378 };
379 
380 static int fq_codel_change(struct Qdisc *sch, struct nlattr *opt,
381                            struct netlink_ext_ack *extack)
382 {
383         struct fq_codel_sched_data *q = qdisc_priv(sch);
384         struct nlattr *tb[TCA_FQ_CODEL_MAX + 1];
385         int err;
386 
387         if (!opt)
388                 return -EINVAL;
389 
390         err = nla_parse_nested(tb, TCA_FQ_CODEL_MAX, opt, fq_codel_policy,
391                                NULL);
392         if (err < 0)
393                 return err;
394         if (tb[TCA_FQ_CODEL_FLOWS]) {
395                 if (q->flows)
396                         return -EINVAL;
397                 q->flows_cnt = nla_get_u32(tb[TCA_FQ_CODEL_FLOWS]);
398                 if (!q->flows_cnt ||
399                     q->flows_cnt > 65536)
400                         return -EINVAL;
401         }
402         sch_tree_lock(sch);
403 
404         if (tb[TCA_FQ_CODEL_TARGET]) {
405                 u64 target = nla_get_u32(tb[TCA_FQ_CODEL_TARGET]);
406 
407                 q->cparams.target = (target * NSEC_PER_USEC) >> CODEL_SHIFT;
408         }
409 
410         if (tb[TCA_FQ_CODEL_CE_THRESHOLD]) {
411                 u64 val = nla_get_u32(tb[TCA_FQ_CODEL_CE_THRESHOLD]);
412 
413                 q->cparams.ce_threshold = (val * NSEC_PER_USEC) >> CODEL_SHIFT;
414         }
415 
416         if (tb[TCA_FQ_CODEL_INTERVAL]) {
417                 u64 interval = nla_get_u32(tb[TCA_FQ_CODEL_INTERVAL]);
418 
419                 q->cparams.interval = (interval * NSEC_PER_USEC) >> CODEL_SHIFT;
420         }
421 
422         if (tb[TCA_FQ_CODEL_LIMIT])
423                 sch->limit = nla_get_u32(tb[TCA_FQ_CODEL_LIMIT]);
424 
425         if (tb[TCA_FQ_CODEL_ECN])
426                 q->cparams.ecn = !!nla_get_u32(tb[TCA_FQ_CODEL_ECN]);
427 
428         if (tb[TCA_FQ_CODEL_QUANTUM])
429                 q->quantum = max(256U, nla_get_u32(tb[TCA_FQ_CODEL_QUANTUM]));
430 
431         if (tb[TCA_FQ_CODEL_DROP_BATCH_SIZE])
432                 q->drop_batch_size = min(1U, nla_get_u32(tb[TCA_FQ_CODEL_DROP_BATCH_SIZE]));
433 
434         if (tb[TCA_FQ_CODEL_MEMORY_LIMIT])
435                 q->memory_limit = min(1U << 31, nla_get_u32(tb[TCA_FQ_CODEL_MEMORY_LIMIT]));
436 
437         while (sch->q.qlen > sch->limit ||
438                q->memory_usage > q->memory_limit) {
439                 struct sk_buff *skb = fq_codel_dequeue(sch);
440 
441                 q->cstats.drop_len += qdisc_pkt_len(skb);
442                 rtnl_kfree_skbs(skb, skb);
443                 q->cstats.drop_count++;
444         }
445         qdisc_tree_reduce_backlog(sch, q->cstats.drop_count, q->cstats.drop_len);
446         q->cstats.drop_count = 0;
447         q->cstats.drop_len = 0;
448 
449         sch_tree_unlock(sch);
450         return 0;
451 }
452 
453 static void fq_codel_destroy(struct Qdisc *sch)
454 {
455         struct fq_codel_sched_data *q = qdisc_priv(sch);
456 
457         tcf_block_put(q->block);
458         kvfree(q->backlogs);
459         kvfree(q->flows);
460 }
461 
462 static int fq_codel_init(struct Qdisc *sch, struct nlattr *opt,
463                          struct netlink_ext_ack *extack)
464 {
465         struct fq_codel_sched_data *q = qdisc_priv(sch);
466         int i;
467         int err;
468 
469         sch->limit = 10*1024;
470         q->flows_cnt = 1024;
471         q->memory_limit = 32 << 20; /* 32 MBytes */
472         q->drop_batch_size = 64;
473         q->quantum = psched_mtu(qdisc_dev(sch));
474         INIT_LIST_HEAD(&q->new_flows);
475         INIT_LIST_HEAD(&q->old_flows);
476         codel_params_init(&q->cparams);
477         codel_stats_init(&q->cstats);
478         q->cparams.ecn = true;
479         q->cparams.mtu = psched_mtu(qdisc_dev(sch));
480 
481         if (opt) {
482                 err = fq_codel_change(sch, opt, extack);
483                 if (err)
484                         goto init_failure;
485         }
486 
487         err = tcf_block_get(&q->block, &q->filter_list, sch, extack);
488         if (err)
489                 goto init_failure;
490 
491         if (!q->flows) {
492                 q->flows = kvcalloc(q->flows_cnt,
493                                     sizeof(struct fq_codel_flow),
494                                     GFP_KERNEL);
495                 if (!q->flows) {
496                         err = -ENOMEM;
497                         goto init_failure;
498                 }
499                 q->backlogs = kvcalloc(q->flows_cnt, sizeof(u32), GFP_KERNEL);
500                 if (!q->backlogs) {
501                         err = -ENOMEM;
502                         goto alloc_failure;
503                 }
504                 for (i = 0; i < q->flows_cnt; i++) {
505                         struct fq_codel_flow *flow = q->flows + i;
506 
507                         INIT_LIST_HEAD(&flow->flowchain);
508                         codel_vars_init(&flow->cvars);
509                 }
510         }
511         if (sch->limit >= 1)
512                 sch->flags |= TCQ_F_CAN_BYPASS;
513         else
514                 sch->flags &= ~TCQ_F_CAN_BYPASS;
515         return 0;
516 
517 alloc_failure:
518         kvfree(q->flows);
519         q->flows = NULL;
520 init_failure:
521         q->flows_cnt = 0;
522         return err;
523 }
524 
525 static int fq_codel_dump(struct Qdisc *sch, struct sk_buff *skb)
526 {
527         struct fq_codel_sched_data *q = qdisc_priv(sch);
528         struct nlattr *opts;
529 
530         opts = nla_nest_start(skb, TCA_OPTIONS);
531         if (opts == NULL)
532                 goto nla_put_failure;
533 
534         if (nla_put_u32(skb, TCA_FQ_CODEL_TARGET,
535                         codel_time_to_us(q->cparams.target)) ||
536             nla_put_u32(skb, TCA_FQ_CODEL_LIMIT,
537                         sch->limit) ||
538             nla_put_u32(skb, TCA_FQ_CODEL_INTERVAL,
539                         codel_time_to_us(q->cparams.interval)) ||
540             nla_put_u32(skb, TCA_FQ_CODEL_ECN,
541                         q->cparams.ecn) ||
542             nla_put_u32(skb, TCA_FQ_CODEL_QUANTUM,
543                         q->quantum) ||
544             nla_put_u32(skb, TCA_FQ_CODEL_DROP_BATCH_SIZE,
545                         q->drop_batch_size) ||
546             nla_put_u32(skb, TCA_FQ_CODEL_MEMORY_LIMIT,
547                         q->memory_limit) ||
548             nla_put_u32(skb, TCA_FQ_CODEL_FLOWS,
549                         q->flows_cnt))
550                 goto nla_put_failure;
551 
552         if (q->cparams.ce_threshold != CODEL_DISABLED_THRESHOLD &&
553             nla_put_u32(skb, TCA_FQ_CODEL_CE_THRESHOLD,
554                         codel_time_to_us(q->cparams.ce_threshold)))
555                 goto nla_put_failure;
556 
557         return nla_nest_end(skb, opts);
558 
559 nla_put_failure:
560         return -1;
561 }
562 
563 static int fq_codel_dump_stats(struct Qdisc *sch, struct gnet_dump *d)
564 {
565         struct fq_codel_sched_data *q = qdisc_priv(sch);
566         struct tc_fq_codel_xstats st = {
567                 .type                           = TCA_FQ_CODEL_XSTATS_QDISC,
568         };
569         struct list_head *pos;
570 
571         st.qdisc_stats.maxpacket = q->cstats.maxpacket;
572         st.qdisc_stats.drop_overlimit = q->drop_overlimit;
573         st.qdisc_stats.ecn_mark = q->cstats.ecn_mark;
574         st.qdisc_stats.new_flow_count = q->new_flow_count;
575         st.qdisc_stats.ce_mark = q->cstats.ce_mark;
576         st.qdisc_stats.memory_usage  = q->memory_usage;
577         st.qdisc_stats.drop_overmemory = q->drop_overmemory;
578 
579         sch_tree_lock(sch);
580         list_for_each(pos, &q->new_flows)
581                 st.qdisc_stats.new_flows_len++;
582 
583         list_for_each(pos, &q->old_flows)
584                 st.qdisc_stats.old_flows_len++;
585         sch_tree_unlock(sch);
586 
587         return gnet_stats_copy_app(d, &st, sizeof(st));
588 }
589 
590 static struct Qdisc *fq_codel_leaf(struct Qdisc *sch, unsigned long arg)
591 {
592         return NULL;
593 }
594 
595 static unsigned long fq_codel_find(struct Qdisc *sch, u32 classid)
596 {
597         return 0;
598 }
599 
600 static unsigned long fq_codel_bind(struct Qdisc *sch, unsigned long parent,
601                               u32 classid)
602 {
603         return 0;
604 }
605 
606 static void fq_codel_unbind(struct Qdisc *q, unsigned long cl)
607 {
608 }
609 
610 static struct tcf_block *fq_codel_tcf_block(struct Qdisc *sch, unsigned long cl,
611                                             struct netlink_ext_ack *extack)
612 {
613         struct fq_codel_sched_data *q = qdisc_priv(sch);
614 
615         if (cl)
616                 return NULL;
617         return q->block;
618 }
619 
620 static int fq_codel_dump_class(struct Qdisc *sch, unsigned long cl,
621                           struct sk_buff *skb, struct tcmsg *tcm)
622 {
623         tcm->tcm_handle |= TC_H_MIN(cl);
624         return 0;
625 }
626 
627 static int fq_codel_dump_class_stats(struct Qdisc *sch, unsigned long cl,
628                                      struct gnet_dump *d)
629 {
630         struct fq_codel_sched_data *q = qdisc_priv(sch);
631         u32 idx = cl - 1;
632         struct gnet_stats_queue qs = { 0 };
633         struct tc_fq_codel_xstats xstats;
634 
635         if (idx < q->flows_cnt) {
636                 const struct fq_codel_flow *flow = &q->flows[idx];
637                 const struct sk_buff *skb;
638 
639                 memset(&xstats, 0, sizeof(xstats));
640                 xstats.type = TCA_FQ_CODEL_XSTATS_CLASS;
641                 xstats.class_stats.deficit = flow->deficit;
642                 xstats.class_stats.ldelay =
643                         codel_time_to_us(flow->cvars.ldelay);
644                 xstats.class_stats.count = flow->cvars.count;
645                 xstats.class_stats.lastcount = flow->cvars.lastcount;
646                 xstats.class_stats.dropping = flow->cvars.dropping;
647                 if (flow->cvars.dropping) {
648                         codel_tdiff_t delta = flow->cvars.drop_next -
649                                               codel_get_time();
650 
651                         xstats.class_stats.drop_next = (delta >= 0) ?
652                                 codel_time_to_us(delta) :
653                                 -codel_time_to_us(-delta);
654                 }
655                 if (flow->head) {
656                         sch_tree_lock(sch);
657                         skb = flow->head;
658                         while (skb) {
659                                 qs.qlen++;
660                                 skb = skb->next;
661                         }
662                         sch_tree_unlock(sch);
663                 }
664                 qs.backlog = q->backlogs[idx];
665                 qs.drops = flow->dropped;
666         }
667         if (gnet_stats_copy_queue(d, NULL, &qs, qs.qlen) < 0)
668                 return -1;
669         if (idx < q->flows_cnt)
670                 return gnet_stats_copy_app(d, &xstats, sizeof(xstats));
671         return 0;
672 }
673 
674 static void fq_codel_walk(struct Qdisc *sch, struct qdisc_walker *arg)
675 {
676         struct fq_codel_sched_data *q = qdisc_priv(sch);
677         unsigned int i;
678 
679         if (arg->stop)
680                 return;
681 
682         for (i = 0; i < q->flows_cnt; i++) {
683                 if (list_empty(&q->flows[i].flowchain) ||
684                     arg->count < arg->skip) {
685                         arg->count++;
686                         continue;
687                 }
688                 if (arg->fn(sch, i + 1, arg) < 0) {
689                         arg->stop = 1;
690                         break;
691                 }
692                 arg->count++;
693         }
694 }
695 
696 static const struct Qdisc_class_ops fq_codel_class_ops = {
697         .leaf           =       fq_codel_leaf,
698         .find           =       fq_codel_find,
699         .tcf_block      =       fq_codel_tcf_block,
700         .bind_tcf       =       fq_codel_bind,
701         .unbind_tcf     =       fq_codel_unbind,
702         .dump           =       fq_codel_dump_class,
703         .dump_stats     =       fq_codel_dump_class_stats,
704         .walk           =       fq_codel_walk,
705 };
706 
707 static struct Qdisc_ops fq_codel_qdisc_ops __read_mostly = {
708         .cl_ops         =       &fq_codel_class_ops,
709         .id             =       "fq_codel",
710         .priv_size      =       sizeof(struct fq_codel_sched_data),
711         .enqueue        =       fq_codel_enqueue,
712         .dequeue        =       fq_codel_dequeue,
713         .peek           =       qdisc_peek_dequeued,
714         .init           =       fq_codel_init,
715         .reset          =       fq_codel_reset,
716         .destroy        =       fq_codel_destroy,
717         .change         =       fq_codel_change,
718         .dump           =       fq_codel_dump,
719         .dump_stats =   fq_codel_dump_stats,
720         .owner          =       THIS_MODULE,
721 };
722 
723 static int __init fq_codel_module_init(void)
724 {
725         return register_qdisc(&fq_codel_qdisc_ops);
726 }
727 
728 static void __exit fq_codel_module_exit(void)
729 {
730         unregister_qdisc(&fq_codel_qdisc_ops);
731 }
732 
733 module_init(fq_codel_module_init)
734 module_exit(fq_codel_module_exit)
735 MODULE_AUTHOR("Eric Dumazet");
736 MODULE_LICENSE("GPL");
737 

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