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Linux/net/sched/sch_fq_codel.c

  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/codel.h>
 27 #include <net/codel_impl.h>
 28 #include <net/codel_qdisc.h>
 29 
 30 /*      Fair Queue CoDel.
 31  *
 32  * Principles :
 33  * Packets are classified (internal classifier or external) on flows.
 34  * This is a Stochastic model (as we use a hash, several flows
 35  *                             might be hashed on same slot)
 36  * Each flow has a CoDel managed queue.
 37  * Flows are linked onto two (Round Robin) lists,
 38  * so that new flows have priority on old ones.
 39  *
 40  * For a given flow, packets are not reordered (CoDel uses a FIFO)
 41  * head drops only.
 42  * ECN capability is on by default.
 43  * Low memory footprint (64 bytes per flow)
 44  */
 45 
 46 struct fq_codel_flow {
 47         struct sk_buff    *head;
 48         struct sk_buff    *tail;
 49         struct list_head  flowchain;
 50         int               deficit;
 51         u32               dropped; /* number of drops (or ECN marks) on this flow */
 52         struct codel_vars cvars;
 53 }; /* please try to keep this structure <= 64 bytes */
 54 
 55 struct fq_codel_sched_data {
 56         struct tcf_proto __rcu *filter_list; /* optional external classifier */
 57         struct fq_codel_flow *flows;    /* Flows table [flows_cnt] */
 58         u32             *backlogs;      /* backlog table [flows_cnt] */
 59         u32             flows_cnt;      /* number of flows */
 60         u32             perturbation;   /* hash perturbation */
 61         u32             quantum;        /* psched_mtu(qdisc_dev(sch)); */
 62         u32             drop_batch_size;
 63         u32             memory_limit;
 64         struct codel_params cparams;
 65         struct codel_stats cstats;
 66         u32             memory_usage;
 67         u32             drop_overmemory;
 68         u32             drop_overlimit;
 69         u32             new_flow_count;
 70 
 71         struct list_head new_flows;     /* list of new flows */
 72         struct list_head old_flows;     /* list of old flows */
 73 };
 74 
 75 static unsigned int fq_codel_hash(const struct fq_codel_sched_data *q,
 76                                   struct sk_buff *skb)
 77 {
 78         u32 hash = skb_get_hash_perturb(skb, q->perturbation);
 79 
 80         return reciprocal_scale(hash, q->flows_cnt);
 81 }
 82 
 83 static unsigned int fq_codel_classify(struct sk_buff *skb, struct Qdisc *sch,
 84                                       int *qerr)
 85 {
 86         struct fq_codel_sched_data *q = qdisc_priv(sch);
 87         struct tcf_proto *filter;
 88         struct tcf_result res;
 89         int result;
 90 
 91         if (TC_H_MAJ(skb->priority) == sch->handle &&
 92             TC_H_MIN(skb->priority) > 0 &&
 93             TC_H_MIN(skb->priority) <= q->flows_cnt)
 94                 return TC_H_MIN(skb->priority);
 95 
 96         filter = rcu_dereference_bh(q->filter_list);
 97         if (!filter)
 98                 return fq_codel_hash(q, skb) + 1;
 99 
100         *qerr = NET_XMIT_SUCCESS | __NET_XMIT_BYPASS;
101         result = tc_classify(skb, filter, &res, false);
102         if (result >= 0) {
103 #ifdef CONFIG_NET_CLS_ACT
104                 switch (result) {
105                 case TC_ACT_STOLEN:
106                 case TC_ACT_QUEUED:
107                         *qerr = NET_XMIT_SUCCESS | __NET_XMIT_STOLEN;
108                 case TC_ACT_SHOT:
109                         return 0;
110                 }
111 #endif
112                 if (TC_H_MIN(res.classid) <= q->flows_cnt)
113                         return TC_H_MIN(res.classid);
114         }
115         return 0;
116 }
117 
118 /* helper functions : might be changed when/if skb use a standard list_head */
119 
120 /* remove one skb from head of slot queue */
121 static inline struct sk_buff *dequeue_head(struct fq_codel_flow *flow)
122 {
123         struct sk_buff *skb = flow->head;
124 
125         flow->head = skb->next;
126         skb->next = NULL;
127         return skb;
128 }
129 
130 /* add skb to flow queue (tail add) */
131 static inline void flow_queue_add(struct fq_codel_flow *flow,
132                                   struct sk_buff *skb)
133 {
134         if (flow->head == NULL)
135                 flow->head = skb;
136         else
137                 flow->tail->next = skb;
138         flow->tail = skb;
139         skb->next = NULL;
140 }
141 
142 static unsigned int fq_codel_drop(struct Qdisc *sch, unsigned int max_packets)
143 {
144         struct fq_codel_sched_data *q = qdisc_priv(sch);
145         struct sk_buff *skb;
146         unsigned int maxbacklog = 0, idx = 0, i, len;
147         struct fq_codel_flow *flow;
148         unsigned int threshold;
149         unsigned int mem = 0;
150 
151         /* Queue is full! Find the fat flow and drop packet(s) from it.
152          * This might sound expensive, but with 1024 flows, we scan
153          * 4KB of memory, and we dont need to handle a complex tree
154          * in fast path (packet queue/enqueue) with many cache misses.
155          * In stress mode, we'll try to drop 64 packets from the flow,
156          * amortizing this linear lookup to one cache line per drop.
157          */
158         for (i = 0; i < q->flows_cnt; i++) {
159                 if (q->backlogs[i] > maxbacklog) {
160                         maxbacklog = q->backlogs[i];
161                         idx = i;
162                 }
163         }
164 
165         /* Our goal is to drop half of this fat flow backlog */
166         threshold = maxbacklog >> 1;
167 
168         flow = &q->flows[idx];
169         len = 0;
170         i = 0;
171         do {
172                 skb = dequeue_head(flow);
173                 len += qdisc_pkt_len(skb);
174                 mem += skb->truesize;
175                 kfree_skb(skb);
176         } while (++i < max_packets && len < threshold);
177 
178         flow->dropped += i;
179         q->backlogs[idx] -= len;
180         q->memory_usage -= mem;
181         sch->qstats.drops += i;
182         sch->qstats.backlog -= len;
183         sch->q.qlen -= i;
184         return idx;
185 }
186 
187 static unsigned int fq_codel_qdisc_drop(struct Qdisc *sch)
188 {
189         unsigned int prev_backlog;
190 
191         prev_backlog = sch->qstats.backlog;
192         fq_codel_drop(sch, 1U);
193         return prev_backlog - sch->qstats.backlog;
194 }
195 
196 static int fq_codel_enqueue(struct sk_buff *skb, struct Qdisc *sch)
197 {
198         struct fq_codel_sched_data *q = qdisc_priv(sch);
199         unsigned int idx, prev_backlog, prev_qlen;
200         struct fq_codel_flow *flow;
201         int uninitialized_var(ret);
202         unsigned int pkt_len;
203         bool memory_limited;
204 
205         idx = fq_codel_classify(skb, sch, &ret);
206         if (idx == 0) {
207                 if (ret & __NET_XMIT_BYPASS)
208                         qdisc_qstats_drop(sch);
209                 kfree_skb(skb);
210                 return ret;
211         }
212         idx--;
213 
214         codel_set_enqueue_time(skb);
215         flow = &q->flows[idx];
216         flow_queue_add(flow, skb);
217         q->backlogs[idx] += qdisc_pkt_len(skb);
218         qdisc_qstats_backlog_inc(sch, skb);
219 
220         if (list_empty(&flow->flowchain)) {
221                 list_add_tail(&flow->flowchain, &q->new_flows);
222                 q->new_flow_count++;
223                 flow->deficit = q->quantum;
224                 flow->dropped = 0;
225         }
226         q->memory_usage += skb->truesize;
227         memory_limited = q->memory_usage > q->memory_limit;
228         if (++sch->q.qlen <= sch->limit && !memory_limited)
229                 return NET_XMIT_SUCCESS;
230 
231         prev_backlog = sch->qstats.backlog;
232         prev_qlen = sch->q.qlen;
233 
234         /* save this packet length as it might be dropped by fq_codel_drop() */
235         pkt_len = qdisc_pkt_len(skb);
236         /* fq_codel_drop() is quite expensive, as it performs a linear search
237          * in q->backlogs[] to find a fat flow.
238          * So instead of dropping a single packet, drop half of its backlog
239          * with a 64 packets limit to not add a too big cpu spike here.
240          */
241         ret = fq_codel_drop(sch, q->drop_batch_size);
242 
243         prev_qlen -= sch->q.qlen;
244         prev_backlog -= sch->qstats.backlog;
245         q->drop_overlimit += prev_qlen;
246         if (memory_limited)
247                 q->drop_overmemory += prev_qlen;
248 
249         /* As we dropped packet(s), better let upper stack know this.
250          * If we dropped a packet for this flow, return NET_XMIT_CN,
251          * but in this case, our parents wont increase their backlogs.
252          */
253         if (ret == idx) {
254                 qdisc_tree_reduce_backlog(sch, prev_qlen - 1,
255                                           prev_backlog - pkt_len);
256                 return NET_XMIT_CN;
257         }
258         qdisc_tree_reduce_backlog(sch, prev_qlen, prev_backlog);
259         return NET_XMIT_SUCCESS;
260 }
261 
262 /* This is the specific function called from codel_dequeue()
263  * to dequeue a packet from queue. Note: backlog is handled in
264  * codel, we dont need to reduce it here.
265  */
266 static struct sk_buff *dequeue_func(struct codel_vars *vars, void *ctx)
267 {
268         struct Qdisc *sch = ctx;
269         struct fq_codel_sched_data *q = qdisc_priv(sch);
270         struct fq_codel_flow *flow;
271         struct sk_buff *skb = NULL;
272 
273         flow = container_of(vars, struct fq_codel_flow, cvars);
274         if (flow->head) {
275                 skb = dequeue_head(flow);
276                 q->backlogs[flow - q->flows] -= qdisc_pkt_len(skb);
277                 q->memory_usage -= skb->truesize;
278                 sch->q.qlen--;
279                 sch->qstats.backlog -= qdisc_pkt_len(skb);
280         }
281         return skb;
282 }
283 
284 static void drop_func(struct sk_buff *skb, void *ctx)
285 {
286         struct Qdisc *sch = ctx;
287 
288         qdisc_drop(skb, sch);
289 }
290 
291 static struct sk_buff *fq_codel_dequeue(struct Qdisc *sch)
292 {
293         struct fq_codel_sched_data *q = qdisc_priv(sch);
294         struct sk_buff *skb;
295         struct fq_codel_flow *flow;
296         struct list_head *head;
297         u32 prev_drop_count, prev_ecn_mark;
298         unsigned int prev_backlog;
299 
300 begin:
301         head = &q->new_flows;
302         if (list_empty(head)) {
303                 head = &q->old_flows;
304                 if (list_empty(head))
305                         return NULL;
306         }
307         flow = list_first_entry(head, struct fq_codel_flow, flowchain);
308 
309         if (flow->deficit <= 0) {
310                 flow->deficit += q->quantum;
311                 list_move_tail(&flow->flowchain, &q->old_flows);
312                 goto begin;
313         }
314 
315         prev_drop_count = q->cstats.drop_count;
316         prev_ecn_mark = q->cstats.ecn_mark;
317         prev_backlog = sch->qstats.backlog;
318 
319         skb = codel_dequeue(sch, &sch->qstats.backlog, &q->cparams,
320                             &flow->cvars, &q->cstats, qdisc_pkt_len,
321                             codel_get_enqueue_time, drop_func, dequeue_func);
322 
323         flow->dropped += q->cstats.drop_count - prev_drop_count;
324         flow->dropped += q->cstats.ecn_mark - prev_ecn_mark;
325 
326         if (!skb) {
327                 /* force a pass through old_flows to prevent starvation */
328                 if ((head == &q->new_flows) && !list_empty(&q->old_flows))
329                         list_move_tail(&flow->flowchain, &q->old_flows);
330                 else
331                         list_del_init(&flow->flowchain);
332                 goto begin;
333         }
334         qdisc_bstats_update(sch, skb);
335         flow->deficit -= qdisc_pkt_len(skb);
336         /* We cant call qdisc_tree_reduce_backlog() if our qlen is 0,
337          * or HTB crashes. Defer it for next round.
338          */
339         if (q->cstats.drop_count && sch->q.qlen) {
340                 qdisc_tree_reduce_backlog(sch, q->cstats.drop_count,
341                                           q->cstats.drop_len);
342                 q->cstats.drop_count = 0;
343                 q->cstats.drop_len = 0;
344         }
345         return skb;
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                 while (flow->head) {
359                         struct sk_buff *skb = dequeue_head(flow);
360 
361                         qdisc_qstats_backlog_dec(sch, skb);
362                         kfree_skb(skb);
363                 }
364 
365                 INIT_LIST_HEAD(&flow->flowchain);
366                 codel_vars_init(&flow->cvars);
367         }
368         memset(q->backlogs, 0, q->flows_cnt * sizeof(u32));
369         sch->q.qlen = 0;
370         q->memory_usage = 0;
371 }
372 
373 static const struct nla_policy fq_codel_policy[TCA_FQ_CODEL_MAX + 1] = {
374         [TCA_FQ_CODEL_TARGET]   = { .type = NLA_U32 },
375         [TCA_FQ_CODEL_LIMIT]    = { .type = NLA_U32 },
376         [TCA_FQ_CODEL_INTERVAL] = { .type = NLA_U32 },
377         [TCA_FQ_CODEL_ECN]      = { .type = NLA_U32 },
378         [TCA_FQ_CODEL_FLOWS]    = { .type = NLA_U32 },
379         [TCA_FQ_CODEL_QUANTUM]  = { .type = NLA_U32 },
380         [TCA_FQ_CODEL_CE_THRESHOLD] = { .type = NLA_U32 },
381         [TCA_FQ_CODEL_DROP_BATCH_SIZE] = { .type = NLA_U32 },
382         [TCA_FQ_CODEL_MEMORY_LIMIT] = { .type = NLA_U32 },
383 };
384 
385 static int fq_codel_change(struct Qdisc *sch, struct nlattr *opt)
386 {
387         struct fq_codel_sched_data *q = qdisc_priv(sch);
388         struct nlattr *tb[TCA_FQ_CODEL_MAX + 1];
389         int err;
390 
391         if (!opt)
392                 return -EINVAL;
393 
394         err = nla_parse_nested(tb, TCA_FQ_CODEL_MAX, opt, fq_codel_policy);
395         if (err < 0)
396                 return err;
397         if (tb[TCA_FQ_CODEL_FLOWS]) {
398                 if (q->flows)
399                         return -EINVAL;
400                 q->flows_cnt = nla_get_u32(tb[TCA_FQ_CODEL_FLOWS]);
401                 if (!q->flows_cnt ||
402                     q->flows_cnt > 65536)
403                         return -EINVAL;
404         }
405         sch_tree_lock(sch);
406 
407         if (tb[TCA_FQ_CODEL_TARGET]) {
408                 u64 target = nla_get_u32(tb[TCA_FQ_CODEL_TARGET]);
409 
410                 q->cparams.target = (target * NSEC_PER_USEC) >> CODEL_SHIFT;
411         }
412 
413         if (tb[TCA_FQ_CODEL_CE_THRESHOLD]) {
414                 u64 val = nla_get_u32(tb[TCA_FQ_CODEL_CE_THRESHOLD]);
415 
416                 q->cparams.ce_threshold = (val * NSEC_PER_USEC) >> CODEL_SHIFT;
417         }
418 
419         if (tb[TCA_FQ_CODEL_INTERVAL]) {
420                 u64 interval = nla_get_u32(tb[TCA_FQ_CODEL_INTERVAL]);
421 
422                 q->cparams.interval = (interval * NSEC_PER_USEC) >> CODEL_SHIFT;
423         }
424 
425         if (tb[TCA_FQ_CODEL_LIMIT])
426                 sch->limit = nla_get_u32(tb[TCA_FQ_CODEL_LIMIT]);
427 
428         if (tb[TCA_FQ_CODEL_ECN])
429                 q->cparams.ecn = !!nla_get_u32(tb[TCA_FQ_CODEL_ECN]);
430 
431         if (tb[TCA_FQ_CODEL_QUANTUM])
432                 q->quantum = max(256U, nla_get_u32(tb[TCA_FQ_CODEL_QUANTUM]));
433 
434         if (tb[TCA_FQ_CODEL_DROP_BATCH_SIZE])
435                 q->drop_batch_size = min(1U, nla_get_u32(tb[TCA_FQ_CODEL_DROP_BATCH_SIZE]));
436 
437         if (tb[TCA_FQ_CODEL_MEMORY_LIMIT])
438                 q->memory_limit = min(1U << 31, nla_get_u32(tb[TCA_FQ_CODEL_MEMORY_LIMIT]));
439 
440         while (sch->q.qlen > sch->limit ||
441                q->memory_usage > q->memory_limit) {
442                 struct sk_buff *skb = fq_codel_dequeue(sch);
443 
444                 q->cstats.drop_len += qdisc_pkt_len(skb);
445                 kfree_skb(skb);
446                 q->cstats.drop_count++;
447         }
448         qdisc_tree_reduce_backlog(sch, q->cstats.drop_count, q->cstats.drop_len);
449         q->cstats.drop_count = 0;
450         q->cstats.drop_len = 0;
451 
452         sch_tree_unlock(sch);
453         return 0;
454 }
455 
456 static void *fq_codel_zalloc(size_t sz)
457 {
458         void *ptr = kzalloc(sz, GFP_KERNEL | __GFP_NOWARN);
459 
460         if (!ptr)
461                 ptr = vzalloc(sz);
462         return ptr;
463 }
464 
465 static void fq_codel_free(void *addr)
466 {
467         kvfree(addr);
468 }
469 
470 static void fq_codel_destroy(struct Qdisc *sch)
471 {
472         struct fq_codel_sched_data *q = qdisc_priv(sch);
473 
474         tcf_destroy_chain(&q->filter_list);
475         fq_codel_free(q->backlogs);
476         fq_codel_free(q->flows);
477 }
478 
479 static int fq_codel_init(struct Qdisc *sch, struct nlattr *opt)
480 {
481         struct fq_codel_sched_data *q = qdisc_priv(sch);
482         int i;
483 
484         sch->limit = 10*1024;
485         q->flows_cnt = 1024;
486         q->memory_limit = 32 << 20; /* 32 MBytes */
487         q->drop_batch_size = 64;
488         q->quantum = psched_mtu(qdisc_dev(sch));
489         q->perturbation = prandom_u32();
490         INIT_LIST_HEAD(&q->new_flows);
491         INIT_LIST_HEAD(&q->old_flows);
492         codel_params_init(&q->cparams);
493         codel_stats_init(&q->cstats);
494         q->cparams.ecn = true;
495         q->cparams.mtu = psched_mtu(qdisc_dev(sch));
496 
497         if (opt) {
498                 int err = fq_codel_change(sch, opt);
499                 if (err)
500                         return err;
501         }
502 
503         if (!q->flows) {
504                 q->flows = fq_codel_zalloc(q->flows_cnt *
505                                            sizeof(struct fq_codel_flow));
506                 if (!q->flows)
507                         return -ENOMEM;
508                 q->backlogs = fq_codel_zalloc(q->flows_cnt * sizeof(u32));
509                 if (!q->backlogs) {
510                         fq_codel_free(q->flows);
511                         return -ENOMEM;
512                 }
513                 for (i = 0; i < q->flows_cnt; i++) {
514                         struct fq_codel_flow *flow = q->flows + i;
515 
516                         INIT_LIST_HEAD(&flow->flowchain);
517                         codel_vars_init(&flow->cvars);
518                 }
519         }
520         if (sch->limit >= 1)
521                 sch->flags |= TCQ_F_CAN_BYPASS;
522         else
523                 sch->flags &= ~TCQ_F_CAN_BYPASS;
524         return 0;
525 }
526 
527 static int fq_codel_dump(struct Qdisc *sch, struct sk_buff *skb)
528 {
529         struct fq_codel_sched_data *q = qdisc_priv(sch);
530         struct nlattr *opts;
531 
532         opts = nla_nest_start(skb, TCA_OPTIONS);
533         if (opts == NULL)
534                 goto nla_put_failure;
535 
536         if (nla_put_u32(skb, TCA_FQ_CODEL_TARGET,
537                         codel_time_to_us(q->cparams.target)) ||
538             nla_put_u32(skb, TCA_FQ_CODEL_LIMIT,
539                         sch->limit) ||
540             nla_put_u32(skb, TCA_FQ_CODEL_INTERVAL,
541                         codel_time_to_us(q->cparams.interval)) ||
542             nla_put_u32(skb, TCA_FQ_CODEL_ECN,
543                         q->cparams.ecn) ||
544             nla_put_u32(skb, TCA_FQ_CODEL_QUANTUM,
545                         q->quantum) ||
546             nla_put_u32(skb, TCA_FQ_CODEL_DROP_BATCH_SIZE,
547                         q->drop_batch_size) ||
548             nla_put_u32(skb, TCA_FQ_CODEL_MEMORY_LIMIT,
549                         q->memory_limit) ||
550             nla_put_u32(skb, TCA_FQ_CODEL_FLOWS,
551                         q->flows_cnt))
552                 goto nla_put_failure;
553 
554         if (q->cparams.ce_threshold != CODEL_DISABLED_THRESHOLD &&
555             nla_put_u32(skb, TCA_FQ_CODEL_CE_THRESHOLD,
556                         codel_time_to_us(q->cparams.ce_threshold)))
557                 goto nla_put_failure;
558 
559         return nla_nest_end(skb, opts);
560 
561 nla_put_failure:
562         return -1;
563 }
564 
565 static int fq_codel_dump_stats(struct Qdisc *sch, struct gnet_dump *d)
566 {
567         struct fq_codel_sched_data *q = qdisc_priv(sch);
568         struct tc_fq_codel_xstats st = {
569                 .type                           = TCA_FQ_CODEL_XSTATS_QDISC,
570         };
571         struct list_head *pos;
572 
573         st.qdisc_stats.maxpacket = q->cstats.maxpacket;
574         st.qdisc_stats.drop_overlimit = q->drop_overlimit;
575         st.qdisc_stats.ecn_mark = q->cstats.ecn_mark;
576         st.qdisc_stats.new_flow_count = q->new_flow_count;
577         st.qdisc_stats.ce_mark = q->cstats.ce_mark;
578         st.qdisc_stats.memory_usage  = q->memory_usage;
579         st.qdisc_stats.drop_overmemory = q->drop_overmemory;
580 
581         list_for_each(pos, &q->new_flows)
582                 st.qdisc_stats.new_flows_len++;
583 
584         list_for_each(pos, &q->old_flows)
585                 st.qdisc_stats.old_flows_len++;
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_get(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         /* we cannot bypass queue discipline anymore */
604         sch->flags &= ~TCQ_F_CAN_BYPASS;
605         return 0;
606 }
607 
608 static void fq_codel_put(struct Qdisc *q, unsigned long cl)
609 {
610 }
611 
612 static struct tcf_proto __rcu **fq_codel_find_tcf(struct Qdisc *sch,
613                                                   unsigned long cl)
614 {
615         struct fq_codel_sched_data *q = qdisc_priv(sch);
616 
617         if (cl)
618                 return NULL;
619         return &q->filter_list;
620 }
621 
622 static int fq_codel_dump_class(struct Qdisc *sch, unsigned long cl,
623                           struct sk_buff *skb, struct tcmsg *tcm)
624 {
625         tcm->tcm_handle |= TC_H_MIN(cl);
626         return 0;
627 }
628 
629 static int fq_codel_dump_class_stats(struct Qdisc *sch, unsigned long cl,
630                                      struct gnet_dump *d)
631 {
632         struct fq_codel_sched_data *q = qdisc_priv(sch);
633         u32 idx = cl - 1;
634         struct gnet_stats_queue qs = { 0 };
635         struct tc_fq_codel_xstats xstats;
636 
637         if (idx < q->flows_cnt) {
638                 const struct fq_codel_flow *flow = &q->flows[idx];
639                 const struct sk_buff *skb = flow->head;
640 
641                 memset(&xstats, 0, sizeof(xstats));
642                 xstats.type = TCA_FQ_CODEL_XSTATS_CLASS;
643                 xstats.class_stats.deficit = flow->deficit;
644                 xstats.class_stats.ldelay =
645                         codel_time_to_us(flow->cvars.ldelay);
646                 xstats.class_stats.count = flow->cvars.count;
647                 xstats.class_stats.lastcount = flow->cvars.lastcount;
648                 xstats.class_stats.dropping = flow->cvars.dropping;
649                 if (flow->cvars.dropping) {
650                         codel_tdiff_t delta = flow->cvars.drop_next -
651                                               codel_get_time();
652 
653                         xstats.class_stats.drop_next = (delta >= 0) ?
654                                 codel_time_to_us(delta) :
655                                 -codel_time_to_us(-delta);
656                 }
657                 while (skb) {
658                         qs.qlen++;
659                         skb = skb->next;
660                 }
661                 qs.backlog = q->backlogs[idx];
662                 qs.drops = flow->dropped;
663         }
664         if (gnet_stats_copy_queue(d, NULL, &qs, qs.qlen) < 0)
665                 return -1;
666         if (idx < q->flows_cnt)
667                 return gnet_stats_copy_app(d, &xstats, sizeof(xstats));
668         return 0;
669 }
670 
671 static void fq_codel_walk(struct Qdisc *sch, struct qdisc_walker *arg)
672 {
673         struct fq_codel_sched_data *q = qdisc_priv(sch);
674         unsigned int i;
675 
676         if (arg->stop)
677                 return;
678 
679         for (i = 0; i < q->flows_cnt; i++) {
680                 if (list_empty(&q->flows[i].flowchain) ||
681                     arg->count < arg->skip) {
682                         arg->count++;
683                         continue;
684                 }
685                 if (arg->fn(sch, i + 1, arg) < 0) {
686                         arg->stop = 1;
687                         break;
688                 }
689                 arg->count++;
690         }
691 }
692 
693 static const struct Qdisc_class_ops fq_codel_class_ops = {
694         .leaf           =       fq_codel_leaf,
695         .get            =       fq_codel_get,
696         .put            =       fq_codel_put,
697         .tcf_chain      =       fq_codel_find_tcf,
698         .bind_tcf       =       fq_codel_bind,
699         .unbind_tcf     =       fq_codel_put,
700         .dump           =       fq_codel_dump_class,
701         .dump_stats     =       fq_codel_dump_class_stats,
702         .walk           =       fq_codel_walk,
703 };
704 
705 static struct Qdisc_ops fq_codel_qdisc_ops __read_mostly = {
706         .cl_ops         =       &fq_codel_class_ops,
707         .id             =       "fq_codel",
708         .priv_size      =       sizeof(struct fq_codel_sched_data),
709         .enqueue        =       fq_codel_enqueue,
710         .dequeue        =       fq_codel_dequeue,
711         .peek           =       qdisc_peek_dequeued,
712         .drop           =       fq_codel_qdisc_drop,
713         .init           =       fq_codel_init,
714         .reset          =       fq_codel_reset,
715         .destroy        =       fq_codel_destroy,
716         .change         =       fq_codel_change,
717         .dump           =       fq_codel_dump,
718         .dump_stats =   fq_codel_dump_stats,
719         .owner          =       THIS_MODULE,
720 };
721 
722 static int __init fq_codel_module_init(void)
723 {
724         return register_qdisc(&fq_codel_qdisc_ops);
725 }
726 
727 static void __exit fq_codel_module_exit(void)
728 {
729         unregister_qdisc(&fq_codel_qdisc_ops);
730 }
731 
732 module_init(fq_codel_module_init)
733 module_exit(fq_codel_module_exit)
734 MODULE_AUTHOR("Eric Dumazet");
735 MODULE_LICENSE("GPL");
736 

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