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Linux/net/sched/sch_fq_codel.c

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  1 // SPDX-License-Identifier: GPL-2.0-or-later
  2 /*
  3  * Fair Queue CoDel discipline
  4  *
  5  *  Copyright (C) 2012,2015 Eric Dumazet <edumazet@google.com>
  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/slab.h>
 18 #include <linux/vmalloc.h>
 19 #include <net/netlink.h>
 20 #include <net/pkt_sched.h>
 21 #include <net/pkt_cls.h>
 22 #include <net/codel.h>
 23 #include <net/codel_impl.h>
 24 #include <net/codel_qdisc.h>
 25 
 26 /*      Fair Queue CoDel.
 27  *
 28  * Principles :
 29  * Packets are classified (internal classifier or external) on flows.
 30  * This is a Stochastic model (as we use a hash, several flows
 31  *                             might be hashed on same slot)
 32  * Each flow has a CoDel managed queue.
 33  * Flows are linked onto two (Round Robin) lists,
 34  * so that new flows have priority on old ones.
 35  *
 36  * For a given flow, packets are not reordered (CoDel uses a FIFO)
 37  * head drops only.
 38  * ECN capability is on by default.
 39  * Low memory footprint (64 bytes per flow)
 40  */
 41 
 42 struct fq_codel_flow {
 43         struct sk_buff    *head;
 44         struct sk_buff    *tail;
 45         struct list_head  flowchain;
 46         int               deficit;
 47         struct codel_vars cvars;
 48 }; /* please try to keep this structure <= 64 bytes */
 49 
 50 struct fq_codel_sched_data {
 51         struct tcf_proto __rcu *filter_list; /* optional external classifier */
 52         struct tcf_block *block;
 53         struct fq_codel_flow *flows;    /* Flows table [flows_cnt] */
 54         u32             *backlogs;      /* backlog table [flows_cnt] */
 55         u32             flows_cnt;      /* number of flows */
 56         u32             quantum;        /* psched_mtu(qdisc_dev(sch)); */
 57         u32             drop_batch_size;
 58         u32             memory_limit;
 59         struct codel_params cparams;
 60         struct codel_stats cstats;
 61         u32             memory_usage;
 62         u32             drop_overmemory;
 63         u32             drop_overlimit;
 64         u32             new_flow_count;
 65 
 66         struct list_head new_flows;     /* list of new flows */
 67         struct list_head old_flows;     /* list of old flows */
 68 };
 69 
 70 static unsigned int fq_codel_hash(const struct fq_codel_sched_data *q,
 71                                   struct sk_buff *skb)
 72 {
 73         return reciprocal_scale(skb_get_hash(skb), q->flows_cnt);
 74 }
 75 
 76 static unsigned int fq_codel_classify(struct sk_buff *skb, struct Qdisc *sch,
 77                                       int *qerr)
 78 {
 79         struct fq_codel_sched_data *q = qdisc_priv(sch);
 80         struct tcf_proto *filter;
 81         struct tcf_result res;
 82         int result;
 83 
 84         if (TC_H_MAJ(skb->priority) == sch->handle &&
 85             TC_H_MIN(skb->priority) > 0 &&
 86             TC_H_MIN(skb->priority) <= q->flows_cnt)
 87                 return TC_H_MIN(skb->priority);
 88 
 89         filter = rcu_dereference_bh(q->filter_list);
 90         if (!filter)
 91                 return fq_codel_hash(q, skb) + 1;
 92 
 93         *qerr = NET_XMIT_SUCCESS | __NET_XMIT_BYPASS;
 94         result = tcf_classify(skb, filter, &res, false);
 95         if (result >= 0) {
 96 #ifdef CONFIG_NET_CLS_ACT
 97                 switch (result) {
 98                 case TC_ACT_STOLEN:
 99                 case TC_ACT_QUEUED:
100                 case TC_ACT_TRAP:
101                         *qerr = NET_XMIT_SUCCESS | __NET_XMIT_STOLEN;
102                         fallthrough;
103                 case TC_ACT_SHOT:
104                         return 0;
105                 }
106 #endif
107                 if (TC_H_MIN(res.classid) <= q->flows_cnt)
108                         return TC_H_MIN(res.classid);
109         }
110         return 0;
111 }
112 
113 /* helper functions : might be changed when/if skb use a standard list_head */
114 
115 /* remove one skb from head of slot queue */
116 static inline struct sk_buff *dequeue_head(struct fq_codel_flow *flow)
117 {
118         struct sk_buff *skb = flow->head;
119 
120         flow->head = skb->next;
121         skb_mark_not_on_list(skb);
122         return skb;
123 }
124 
125 /* add skb to flow queue (tail add) */
126 static inline void flow_queue_add(struct fq_codel_flow *flow,
127                                   struct sk_buff *skb)
128 {
129         if (flow->head == NULL)
130                 flow->head = skb;
131         else
132                 flow->tail->next = skb;
133         flow->tail = skb;
134         skb->next = NULL;
135 }
136 
137 static unsigned int fq_codel_drop(struct Qdisc *sch, unsigned int max_packets,
138                                   struct sk_buff **to_free)
139 {
140         struct fq_codel_sched_data *q = qdisc_priv(sch);
141         struct sk_buff *skb;
142         unsigned int maxbacklog = 0, idx = 0, i, len;
143         struct fq_codel_flow *flow;
144         unsigned int threshold;
145         unsigned int mem = 0;
146 
147         /* Queue is full! Find the fat flow and drop packet(s) from it.
148          * This might sound expensive, but with 1024 flows, we scan
149          * 4KB of memory, and we dont need to handle a complex tree
150          * in fast path (packet queue/enqueue) with many cache misses.
151          * In stress mode, we'll try to drop 64 packets from the flow,
152          * amortizing this linear lookup to one cache line per drop.
153          */
154         for (i = 0; i < q->flows_cnt; i++) {
155                 if (q->backlogs[i] > maxbacklog) {
156                         maxbacklog = q->backlogs[i];
157                         idx = i;
158                 }
159         }
160 
161         /* Our goal is to drop half of this fat flow backlog */
162         threshold = maxbacklog >> 1;
163 
164         flow = &q->flows[idx];
165         len = 0;
166         i = 0;
167         do {
168                 skb = dequeue_head(flow);
169                 len += qdisc_pkt_len(skb);
170                 mem += get_codel_cb(skb)->mem_usage;
171                 __qdisc_drop(skb, to_free);
172         } while (++i < max_packets && len < threshold);
173 
174         /* Tell codel to increase its signal strength also */
175         flow->cvars.count += i;
176         q->backlogs[idx] -= len;
177         q->memory_usage -= mem;
178         sch->qstats.drops += i;
179         sch->qstats.backlog -= len;
180         sch->q.qlen -= i;
181         return idx;
182 }
183 
184 static int fq_codel_enqueue(struct sk_buff *skb, struct Qdisc *sch,
185                             struct sk_buff **to_free)
186 {
187         struct fq_codel_sched_data *q = qdisc_priv(sch);
188         unsigned int idx, prev_backlog, prev_qlen;
189         struct fq_codel_flow *flow;
190         int ret;
191         unsigned int pkt_len;
192         bool memory_limited;
193 
194         idx = fq_codel_classify(skb, sch, &ret);
195         if (idx == 0) {
196                 if (ret & __NET_XMIT_BYPASS)
197                         qdisc_qstats_drop(sch);
198                 __qdisc_drop(skb, to_free);
199                 return ret;
200         }
201         idx--;
202 
203         codel_set_enqueue_time(skb);
204         flow = &q->flows[idx];
205         flow_queue_add(flow, skb);
206         q->backlogs[idx] += qdisc_pkt_len(skb);
207         qdisc_qstats_backlog_inc(sch, skb);
208 
209         if (list_empty(&flow->flowchain)) {
210                 list_add_tail(&flow->flowchain, &q->new_flows);
211                 q->new_flow_count++;
212                 flow->deficit = q->quantum;
213         }
214         get_codel_cb(skb)->mem_usage = skb->truesize;
215         q->memory_usage += get_codel_cb(skb)->mem_usage;
216         memory_limited = q->memory_usage > q->memory_limit;
217         if (++sch->q.qlen <= sch->limit && !memory_limited)
218                 return NET_XMIT_SUCCESS;
219 
220         prev_backlog = sch->qstats.backlog;
221         prev_qlen = sch->q.qlen;
222 
223         /* save this packet length as it might be dropped by fq_codel_drop() */
224         pkt_len = qdisc_pkt_len(skb);
225         /* fq_codel_drop() is quite expensive, as it performs a linear search
226          * in q->backlogs[] to find a fat flow.
227          * So instead of dropping a single packet, drop half of its backlog
228          * with a 64 packets limit to not add a too big cpu spike here.
229          */
230         ret = fq_codel_drop(sch, q->drop_batch_size, to_free);
231 
232         prev_qlen -= sch->q.qlen;
233         prev_backlog -= sch->qstats.backlog;
234         q->drop_overlimit += prev_qlen;
235         if (memory_limited)
236                 q->drop_overmemory += prev_qlen;
237 
238         /* As we dropped packet(s), better let upper stack know this.
239          * If we dropped a packet for this flow, return NET_XMIT_CN,
240          * but in this case, our parents wont increase their backlogs.
241          */
242         if (ret == idx) {
243                 qdisc_tree_reduce_backlog(sch, prev_qlen - 1,
244                                           prev_backlog - pkt_len);
245                 return NET_XMIT_CN;
246         }
247         qdisc_tree_reduce_backlog(sch, prev_qlen, prev_backlog);
248         return NET_XMIT_SUCCESS;
249 }
250 
251 /* This is the specific function called from codel_dequeue()
252  * to dequeue a packet from queue. Note: backlog is handled in
253  * codel, we dont need to reduce it here.
254  */
255 static struct sk_buff *dequeue_func(struct codel_vars *vars, void *ctx)
256 {
257         struct Qdisc *sch = ctx;
258         struct fq_codel_sched_data *q = qdisc_priv(sch);
259         struct fq_codel_flow *flow;
260         struct sk_buff *skb = NULL;
261 
262         flow = container_of(vars, struct fq_codel_flow, cvars);
263         if (flow->head) {
264                 skb = dequeue_head(flow);
265                 q->backlogs[flow - q->flows] -= qdisc_pkt_len(skb);
266                 q->memory_usage -= get_codel_cb(skb)->mem_usage;
267                 sch->q.qlen--;
268                 sch->qstats.backlog -= qdisc_pkt_len(skb);
269         }
270         return skb;
271 }
272 
273 static void drop_func(struct sk_buff *skb, void *ctx)
274 {
275         struct Qdisc *sch = ctx;
276 
277         kfree_skb(skb);
278         qdisc_qstats_drop(sch);
279 }
280 
281 static struct sk_buff *fq_codel_dequeue(struct Qdisc *sch)
282 {
283         struct fq_codel_sched_data *q = qdisc_priv(sch);
284         struct sk_buff *skb;
285         struct fq_codel_flow *flow;
286         struct list_head *head;
287 
288 begin:
289         head = &q->new_flows;
290         if (list_empty(head)) {
291                 head = &q->old_flows;
292                 if (list_empty(head))
293                         return NULL;
294         }
295         flow = list_first_entry(head, struct fq_codel_flow, flowchain);
296 
297         if (flow->deficit <= 0) {
298                 flow->deficit += q->quantum;
299                 list_move_tail(&flow->flowchain, &q->old_flows);
300                 goto begin;
301         }
302 
303         skb = codel_dequeue(sch, &sch->qstats.backlog, &q->cparams,
304                             &flow->cvars, &q->cstats, qdisc_pkt_len,
305                             codel_get_enqueue_time, drop_func, dequeue_func);
306 
307         if (!skb) {
308                 /* force a pass through old_flows to prevent starvation */
309                 if ((head == &q->new_flows) && !list_empty(&q->old_flows))
310                         list_move_tail(&flow->flowchain, &q->old_flows);
311                 else
312                         list_del_init(&flow->flowchain);
313                 goto begin;
314         }
315         qdisc_bstats_update(sch, skb);
316         flow->deficit -= qdisc_pkt_len(skb);
317         /* We cant call qdisc_tree_reduce_backlog() if our qlen is 0,
318          * or HTB crashes. Defer it for next round.
319          */
320         if (q->cstats.drop_count && sch->q.qlen) {
321                 qdisc_tree_reduce_backlog(sch, q->cstats.drop_count,
322                                           q->cstats.drop_len);
323                 q->cstats.drop_count = 0;
324                 q->cstats.drop_len = 0;
325         }
326         return skb;
327 }
328 
329 static void fq_codel_flow_purge(struct fq_codel_flow *flow)
330 {
331         rtnl_kfree_skbs(flow->head, flow->tail);
332         flow->head = NULL;
333 }
334 
335 static void fq_codel_reset(struct Qdisc *sch)
336 {
337         struct fq_codel_sched_data *q = qdisc_priv(sch);
338         int i;
339 
340         INIT_LIST_HEAD(&q->new_flows);
341         INIT_LIST_HEAD(&q->old_flows);
342         for (i = 0; i < q->flows_cnt; i++) {
343                 struct fq_codel_flow *flow = q->flows + i;
344 
345                 fq_codel_flow_purge(flow);
346                 INIT_LIST_HEAD(&flow->flowchain);
347                 codel_vars_init(&flow->cvars);
348         }
349         memset(q->backlogs, 0, q->flows_cnt * sizeof(u32));
350         sch->q.qlen = 0;
351         sch->qstats.backlog = 0;
352         q->memory_usage = 0;
353 }
354 
355 static const struct nla_policy fq_codel_policy[TCA_FQ_CODEL_MAX + 1] = {
356         [TCA_FQ_CODEL_TARGET]   = { .type = NLA_U32 },
357         [TCA_FQ_CODEL_LIMIT]    = { .type = NLA_U32 },
358         [TCA_FQ_CODEL_INTERVAL] = { .type = NLA_U32 },
359         [TCA_FQ_CODEL_ECN]      = { .type = NLA_U32 },
360         [TCA_FQ_CODEL_FLOWS]    = { .type = NLA_U32 },
361         [TCA_FQ_CODEL_QUANTUM]  = { .type = NLA_U32 },
362         [TCA_FQ_CODEL_CE_THRESHOLD] = { .type = NLA_U32 },
363         [TCA_FQ_CODEL_DROP_BATCH_SIZE] = { .type = NLA_U32 },
364         [TCA_FQ_CODEL_MEMORY_LIMIT] = { .type = NLA_U32 },
365 };
366 
367 static int fq_codel_change(struct Qdisc *sch, struct nlattr *opt,
368                            struct netlink_ext_ack *extack)
369 {
370         struct fq_codel_sched_data *q = qdisc_priv(sch);
371         struct nlattr *tb[TCA_FQ_CODEL_MAX + 1];
372         int err;
373 
374         if (!opt)
375                 return -EINVAL;
376 
377         err = nla_parse_nested_deprecated(tb, TCA_FQ_CODEL_MAX, opt,
378                                           fq_codel_policy, NULL);
379         if (err < 0)
380                 return err;
381         if (tb[TCA_FQ_CODEL_FLOWS]) {
382                 if (q->flows)
383                         return -EINVAL;
384                 q->flows_cnt = nla_get_u32(tb[TCA_FQ_CODEL_FLOWS]);
385                 if (!q->flows_cnt ||
386                     q->flows_cnt > 65536)
387                         return -EINVAL;
388         }
389         sch_tree_lock(sch);
390 
391         if (tb[TCA_FQ_CODEL_TARGET]) {
392                 u64 target = nla_get_u32(tb[TCA_FQ_CODEL_TARGET]);
393 
394                 q->cparams.target = (target * NSEC_PER_USEC) >> CODEL_SHIFT;
395         }
396 
397         if (tb[TCA_FQ_CODEL_CE_THRESHOLD]) {
398                 u64 val = nla_get_u32(tb[TCA_FQ_CODEL_CE_THRESHOLD]);
399 
400                 q->cparams.ce_threshold = (val * NSEC_PER_USEC) >> CODEL_SHIFT;
401         }
402 
403         if (tb[TCA_FQ_CODEL_INTERVAL]) {
404                 u64 interval = nla_get_u32(tb[TCA_FQ_CODEL_INTERVAL]);
405 
406                 q->cparams.interval = (interval * NSEC_PER_USEC) >> CODEL_SHIFT;
407         }
408 
409         if (tb[TCA_FQ_CODEL_LIMIT])
410                 sch->limit = nla_get_u32(tb[TCA_FQ_CODEL_LIMIT]);
411 
412         if (tb[TCA_FQ_CODEL_ECN])
413                 q->cparams.ecn = !!nla_get_u32(tb[TCA_FQ_CODEL_ECN]);
414 
415         if (tb[TCA_FQ_CODEL_QUANTUM])
416                 q->quantum = max(256U, nla_get_u32(tb[TCA_FQ_CODEL_QUANTUM]));
417 
418         if (tb[TCA_FQ_CODEL_DROP_BATCH_SIZE])
419                 q->drop_batch_size = max(1U, nla_get_u32(tb[TCA_FQ_CODEL_DROP_BATCH_SIZE]));
420 
421         if (tb[TCA_FQ_CODEL_MEMORY_LIMIT])
422                 q->memory_limit = min(1U << 31, nla_get_u32(tb[TCA_FQ_CODEL_MEMORY_LIMIT]));
423 
424         while (sch->q.qlen > sch->limit ||
425                q->memory_usage > q->memory_limit) {
426                 struct sk_buff *skb = fq_codel_dequeue(sch);
427 
428                 q->cstats.drop_len += qdisc_pkt_len(skb);
429                 rtnl_kfree_skbs(skb, skb);
430                 q->cstats.drop_count++;
431         }
432         qdisc_tree_reduce_backlog(sch, q->cstats.drop_count, q->cstats.drop_len);
433         q->cstats.drop_count = 0;
434         q->cstats.drop_len = 0;
435 
436         sch_tree_unlock(sch);
437         return 0;
438 }
439 
440 static void fq_codel_destroy(struct Qdisc *sch)
441 {
442         struct fq_codel_sched_data *q = qdisc_priv(sch);
443 
444         tcf_block_put(q->block);
445         kvfree(q->backlogs);
446         kvfree(q->flows);
447 }
448 
449 static int fq_codel_init(struct Qdisc *sch, struct nlattr *opt,
450                          struct netlink_ext_ack *extack)
451 {
452         struct fq_codel_sched_data *q = qdisc_priv(sch);
453         int i;
454         int err;
455 
456         sch->limit = 10*1024;
457         q->flows_cnt = 1024;
458         q->memory_limit = 32 << 20; /* 32 MBytes */
459         q->drop_batch_size = 64;
460         q->quantum = psched_mtu(qdisc_dev(sch));
461         INIT_LIST_HEAD(&q->new_flows);
462         INIT_LIST_HEAD(&q->old_flows);
463         codel_params_init(&q->cparams);
464         codel_stats_init(&q->cstats);
465         q->cparams.ecn = true;
466         q->cparams.mtu = psched_mtu(qdisc_dev(sch));
467 
468         if (opt) {
469                 err = fq_codel_change(sch, opt, extack);
470                 if (err)
471                         goto init_failure;
472         }
473 
474         err = tcf_block_get(&q->block, &q->filter_list, sch, extack);
475         if (err)
476                 goto init_failure;
477 
478         if (!q->flows) {
479                 q->flows = kvcalloc(q->flows_cnt,
480                                     sizeof(struct fq_codel_flow),
481                                     GFP_KERNEL);
482                 if (!q->flows) {
483                         err = -ENOMEM;
484                         goto init_failure;
485                 }
486                 q->backlogs = kvcalloc(q->flows_cnt, sizeof(u32), GFP_KERNEL);
487                 if (!q->backlogs) {
488                         err = -ENOMEM;
489                         goto alloc_failure;
490                 }
491                 for (i = 0; i < q->flows_cnt; i++) {
492                         struct fq_codel_flow *flow = q->flows + i;
493 
494                         INIT_LIST_HEAD(&flow->flowchain);
495                         codel_vars_init(&flow->cvars);
496                 }
497         }
498         if (sch->limit >= 1)
499                 sch->flags |= TCQ_F_CAN_BYPASS;
500         else
501                 sch->flags &= ~TCQ_F_CAN_BYPASS;
502         return 0;
503 
504 alloc_failure:
505         kvfree(q->flows);
506         q->flows = NULL;
507 init_failure:
508         q->flows_cnt = 0;
509         return err;
510 }
511 
512 static int fq_codel_dump(struct Qdisc *sch, struct sk_buff *skb)
513 {
514         struct fq_codel_sched_data *q = qdisc_priv(sch);
515         struct nlattr *opts;
516 
517         opts = nla_nest_start_noflag(skb, TCA_OPTIONS);
518         if (opts == NULL)
519                 goto nla_put_failure;
520 
521         if (nla_put_u32(skb, TCA_FQ_CODEL_TARGET,
522                         codel_time_to_us(q->cparams.target)) ||
523             nla_put_u32(skb, TCA_FQ_CODEL_LIMIT,
524                         sch->limit) ||
525             nla_put_u32(skb, TCA_FQ_CODEL_INTERVAL,
526                         codel_time_to_us(q->cparams.interval)) ||
527             nla_put_u32(skb, TCA_FQ_CODEL_ECN,
528                         q->cparams.ecn) ||
529             nla_put_u32(skb, TCA_FQ_CODEL_QUANTUM,
530                         q->quantum) ||
531             nla_put_u32(skb, TCA_FQ_CODEL_DROP_BATCH_SIZE,
532                         q->drop_batch_size) ||
533             nla_put_u32(skb, TCA_FQ_CODEL_MEMORY_LIMIT,
534                         q->memory_limit) ||
535             nla_put_u32(skb, TCA_FQ_CODEL_FLOWS,
536                         q->flows_cnt))
537                 goto nla_put_failure;
538 
539         if (q->cparams.ce_threshold != CODEL_DISABLED_THRESHOLD &&
540             nla_put_u32(skb, TCA_FQ_CODEL_CE_THRESHOLD,
541                         codel_time_to_us(q->cparams.ce_threshold)))
542                 goto nla_put_failure;
543 
544         return nla_nest_end(skb, opts);
545 
546 nla_put_failure:
547         return -1;
548 }
549 
550 static int fq_codel_dump_stats(struct Qdisc *sch, struct gnet_dump *d)
551 {
552         struct fq_codel_sched_data *q = qdisc_priv(sch);
553         struct tc_fq_codel_xstats st = {
554                 .type                           = TCA_FQ_CODEL_XSTATS_QDISC,
555         };
556         struct list_head *pos;
557 
558         st.qdisc_stats.maxpacket = q->cstats.maxpacket;
559         st.qdisc_stats.drop_overlimit = q->drop_overlimit;
560         st.qdisc_stats.ecn_mark = q->cstats.ecn_mark;
561         st.qdisc_stats.new_flow_count = q->new_flow_count;
562         st.qdisc_stats.ce_mark = q->cstats.ce_mark;
563         st.qdisc_stats.memory_usage  = q->memory_usage;
564         st.qdisc_stats.drop_overmemory = q->drop_overmemory;
565 
566         sch_tree_lock(sch);
567         list_for_each(pos, &q->new_flows)
568                 st.qdisc_stats.new_flows_len++;
569 
570         list_for_each(pos, &q->old_flows)
571                 st.qdisc_stats.old_flows_len++;
572         sch_tree_unlock(sch);
573 
574         return gnet_stats_copy_app(d, &st, sizeof(st));
575 }
576 
577 static struct Qdisc *fq_codel_leaf(struct Qdisc *sch, unsigned long arg)
578 {
579         return NULL;
580 }
581 
582 static unsigned long fq_codel_find(struct Qdisc *sch, u32 classid)
583 {
584         return 0;
585 }
586 
587 static unsigned long fq_codel_bind(struct Qdisc *sch, unsigned long parent,
588                               u32 classid)
589 {
590         return 0;
591 }
592 
593 static void fq_codel_unbind(struct Qdisc *q, unsigned long cl)
594 {
595 }
596 
597 static struct tcf_block *fq_codel_tcf_block(struct Qdisc *sch, unsigned long cl,
598                                             struct netlink_ext_ack *extack)
599 {
600         struct fq_codel_sched_data *q = qdisc_priv(sch);
601 
602         if (cl)
603                 return NULL;
604         return q->block;
605 }
606 
607 static int fq_codel_dump_class(struct Qdisc *sch, unsigned long cl,
608                           struct sk_buff *skb, struct tcmsg *tcm)
609 {
610         tcm->tcm_handle |= TC_H_MIN(cl);
611         return 0;
612 }
613 
614 static int fq_codel_dump_class_stats(struct Qdisc *sch, unsigned long cl,
615                                      struct gnet_dump *d)
616 {
617         struct fq_codel_sched_data *q = qdisc_priv(sch);
618         u32 idx = cl - 1;
619         struct gnet_stats_queue qs = { 0 };
620         struct tc_fq_codel_xstats xstats;
621 
622         if (idx < q->flows_cnt) {
623                 const struct fq_codel_flow *flow = &q->flows[idx];
624                 const struct sk_buff *skb;
625 
626                 memset(&xstats, 0, sizeof(xstats));
627                 xstats.type = TCA_FQ_CODEL_XSTATS_CLASS;
628                 xstats.class_stats.deficit = flow->deficit;
629                 xstats.class_stats.ldelay =
630                         codel_time_to_us(flow->cvars.ldelay);
631                 xstats.class_stats.count = flow->cvars.count;
632                 xstats.class_stats.lastcount = flow->cvars.lastcount;
633                 xstats.class_stats.dropping = flow->cvars.dropping;
634                 if (flow->cvars.dropping) {
635                         codel_tdiff_t delta = flow->cvars.drop_next -
636                                               codel_get_time();
637 
638                         xstats.class_stats.drop_next = (delta >= 0) ?
639                                 codel_time_to_us(delta) :
640                                 -codel_time_to_us(-delta);
641                 }
642                 if (flow->head) {
643                         sch_tree_lock(sch);
644                         skb = flow->head;
645                         while (skb) {
646                                 qs.qlen++;
647                                 skb = skb->next;
648                         }
649                         sch_tree_unlock(sch);
650                 }
651                 qs.backlog = q->backlogs[idx];
652                 qs.drops = 0;
653         }
654         if (gnet_stats_copy_queue(d, NULL, &qs, qs.qlen) < 0)
655                 return -1;
656         if (idx < q->flows_cnt)
657                 return gnet_stats_copy_app(d, &xstats, sizeof(xstats));
658         return 0;
659 }
660 
661 static void fq_codel_walk(struct Qdisc *sch, struct qdisc_walker *arg)
662 {
663         struct fq_codel_sched_data *q = qdisc_priv(sch);
664         unsigned int i;
665 
666         if (arg->stop)
667                 return;
668 
669         for (i = 0; i < q->flows_cnt; i++) {
670                 if (list_empty(&q->flows[i].flowchain) ||
671                     arg->count < arg->skip) {
672                         arg->count++;
673                         continue;
674                 }
675                 if (arg->fn(sch, i + 1, arg) < 0) {
676                         arg->stop = 1;
677                         break;
678                 }
679                 arg->count++;
680         }
681 }
682 
683 static const struct Qdisc_class_ops fq_codel_class_ops = {
684         .leaf           =       fq_codel_leaf,
685         .find           =       fq_codel_find,
686         .tcf_block      =       fq_codel_tcf_block,
687         .bind_tcf       =       fq_codel_bind,
688         .unbind_tcf     =       fq_codel_unbind,
689         .dump           =       fq_codel_dump_class,
690         .dump_stats     =       fq_codel_dump_class_stats,
691         .walk           =       fq_codel_walk,
692 };
693 
694 static struct Qdisc_ops fq_codel_qdisc_ops __read_mostly = {
695         .cl_ops         =       &fq_codel_class_ops,
696         .id             =       "fq_codel",
697         .priv_size      =       sizeof(struct fq_codel_sched_data),
698         .enqueue        =       fq_codel_enqueue,
699         .dequeue        =       fq_codel_dequeue,
700         .peek           =       qdisc_peek_dequeued,
701         .init           =       fq_codel_init,
702         .reset          =       fq_codel_reset,
703         .destroy        =       fq_codel_destroy,
704         .change         =       fq_codel_change,
705         .dump           =       fq_codel_dump,
706         .dump_stats =   fq_codel_dump_stats,
707         .owner          =       THIS_MODULE,
708 };
709 
710 static int __init fq_codel_module_init(void)
711 {
712         return register_qdisc(&fq_codel_qdisc_ops);
713 }
714 
715 static void __exit fq_codel_module_exit(void)
716 {
717         unregister_qdisc(&fq_codel_qdisc_ops);
718 }
719 
720 module_init(fq_codel_module_init)
721 module_exit(fq_codel_module_exit)
722 MODULE_AUTHOR("Eric Dumazet");
723 MODULE_LICENSE("GPL");
724 MODULE_DESCRIPTION("Fair Queue CoDel discipline");
725 

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