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/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->next = NULL;
 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         u32 quantum = 0;
 386         int err;
 387
 388         if (!opt)
 389                 return -EINVAL;
 390
 391         err = nla_parse_nested(tb, TCA_FQ_CODEL_MAX, opt, fq_codel_policy,
 392                                NULL);
 393         if (err < 0)
 394                 return err;
 395         if (tb[TCA_FQ_CODEL_FLOWS]) {
 396                 if (q->flows)
 397                         return -EINVAL;
 398                 q->flows_cnt = nla_get_u32(tb[TCA_FQ_CODEL_FLOWS]);
 399                 if (!q->flows_cnt ||
 400                     q->flows_cnt > 65536)
 401                         return -EINVAL;
 402         }
 403         if (tb[TCA_FQ_CODEL_QUANTUM]) {
 404                 quantum = max(256U, nla_get_u32(tb[TCA_FQ_CODEL_QUANTUM]));
 405                 if (quantum > FQ_CODEL_QUANTUM_MAX) {
 406                         NL_SET_ERR_MSG(extack, "Invalid quantum");
 407                         return -EINVAL;
 408                 }
 409         }
 410         sch_tree_lock(sch);
 411
 412         if (tb[TCA_FQ_CODEL_TARGET]) {
 413                 u64 target = nla_get_u32(tb[TCA_FQ_CODEL_TARGET]);
 414
 415                 q->cparams.target = (target * NSEC_PER_USEC) >> CODEL_SHIFT;
 416         }
 417
 418         if (tb[TCA_FQ_CODEL_CE_THRESHOLD]) {
 419                 u64 val = nla_get_u32(tb[TCA_FQ_CODEL_CE_THRESHOLD]);
 420
 421                 q->cparams.ce_threshold = (val * NSEC_PER_USEC) >> CODEL_SHIFT;
 422         }
 423
 424         if (tb[TCA_FQ_CODEL_INTERVAL]) {
 425                 u64 interval = nla_get_u32(tb[TCA_FQ_CODEL_INTERVAL]);
 426
 427                 q->cparams.interval = (interval * NSEC_PER_USEC) >> CODEL_SHIFT;
 428         }
 429
 430         if (tb[TCA_FQ_CODEL_LIMIT])
 431                 sch->limit = nla_get_u32(tb[TCA_FQ_CODEL_LIMIT]);
 432
 433         if (tb[TCA_FQ_CODEL_ECN])
 434                 q->cparams.ecn = !!nla_get_u32(tb[TCA_FQ_CODEL_ECN]);
 435
 436         if (quantum)
 437                 q->quantum = quantum;
 438
 439         if (tb[TCA_FQ_CODEL_DROP_BATCH_SIZE])
 440                 q->drop_batch_size = max(1U, nla_get_u32(tb[TCA_FQ_CODEL_DROP_BATCH_SIZE]));
 441
 442         if (tb[TCA_FQ_CODEL_MEMORY_LIMIT])
 443                 q->memory_limit = min(1U << 31, nla_get_u32(tb[TCA_FQ_CODEL_MEMORY_LIMIT]));
 444
 445         while (sch->q.qlen > sch->limit ||
 446                q->memory_usage > q->memory_limit) {
 447                 struct sk_buff *skb = fq_codel_dequeue(sch);
 448
 449                 q->cstats.drop_len += qdisc_pkt_len(skb);
 450                 rtnl_kfree_skbs(skb, skb);
 451                 q->cstats.drop_count++;
 452         }
 453         qdisc_tree_reduce_backlog(sch, q->cstats.drop_count, q->cstats.drop_len);
 454         q->cstats.drop_count = 0;
 455         q->cstats.drop_len = 0;
 456
 457         sch_tree_unlock(sch);
 458         return 0;
 459 }
 460
 461 static void fq_codel_destroy(struct Qdisc *sch)
 462 {
 463         struct fq_codel_sched_data *q = qdisc_priv(sch);
 464
 465         tcf_block_put(q->block);
 466         kvfree(q->backlogs);
 467         kvfree(q->flows);
 468 }
 469
 470 static int fq_codel_init(struct Qdisc *sch, struct nlattr *opt,
 471                          struct netlink_ext_ack *extack)
 472 {
 473         struct fq_codel_sched_data *q = qdisc_priv(sch);
 474         int i;
 475         int err;
 476
 477         sch->limit = 10*1024;
 478         q->flows_cnt = 1024;
 479         q->memory_limit = 32 << 20; /* 32 MBytes */
 480         q->drop_batch_size = 64;
 481         q->quantum = psched_mtu(qdisc_dev(sch));
 482         INIT_LIST_HEAD(&q->new_flows);
 483         INIT_LIST_HEAD(&q->old_flows);
 484         codel_params_init(&q->cparams);
 485         codel_stats_init(&q->cstats);
 486         q->cparams.ecn = true;
 487         q->cparams.mtu = psched_mtu(qdisc_dev(sch));
 488
 489         if (opt) {
 490                 err = fq_codel_change(sch, opt, extack);
 491                 if (err)
 492                         goto init_failure;
 493         }
 494
 495         err = tcf_block_get(&q->block, &q->filter_list, sch, extack);
 496         if (err)
 497                 goto init_failure;
 498
 499         if (!q->flows) {
 500                 q->flows = kvcalloc(q->flows_cnt,
 501                                     sizeof(struct fq_codel_flow),
 502                                     GFP_KERNEL);
 503                 if (!q->flows) {
 504                         err = -ENOMEM;
 505                         goto init_failure;
 506                 }
 507                 q->backlogs = kvcalloc(q->flows_cnt, sizeof(u32), GFP_KERNEL);
 508                 if (!q->backlogs) {
 509                         err = -ENOMEM;
 510                         goto alloc_failure;
 511                 }
 512                 for (i = 0; i < q->flows_cnt; i++) {
 513                         struct fq_codel_flow *flow = q->flows + i;
 514
 515                         INIT_LIST_HEAD(&flow->flowchain);
 516                         codel_vars_init(&flow->cvars);
 517                 }
 518         }
 519         if (sch->limit >= 1)
 520                 sch->flags |= TCQ_F_CAN_BYPASS;
 521         else
 522                 sch->flags &= ~TCQ_F_CAN_BYPASS;
 523         return 0;
 524
 525 alloc_failure:
 526         kvfree(q->flows);
 527         q->flows = NULL;
 528 init_failure:
 529         q->flows_cnt = 0;
 530         return err;
 531 }
 532
 533 static int fq_codel_dump(struct Qdisc *sch, struct sk_buff *skb)
 534 {
 535         struct fq_codel_sched_data *q = qdisc_priv(sch);
 536         struct nlattr *opts;
 537
 538         opts = nla_nest_start(skb, TCA_OPTIONS);
 539         if (opts == NULL)
 540                 goto nla_put_failure;
 541
 542         if (nla_put_u32(skb, TCA_FQ_CODEL_TARGET,
 543                         codel_time_to_us(q->cparams.target)) ||
 544             nla_put_u32(skb, TCA_FQ_CODEL_LIMIT,
 545                         sch->limit) ||
 546             nla_put_u32(skb, TCA_FQ_CODEL_INTERVAL,
 547                         codel_time_to_us(q->cparams.interval)) ||
 548             nla_put_u32(skb, TCA_FQ_CODEL_ECN,
 549                         q->cparams.ecn) ||
 550             nla_put_u32(skb, TCA_FQ_CODEL_QUANTUM,
 551                         q->quantum) ||
 552             nla_put_u32(skb, TCA_FQ_CODEL_DROP_BATCH_SIZE,
 553                         q->drop_batch_size) ||
 554             nla_put_u32(skb, TCA_FQ_CODEL_MEMORY_LIMIT,
 555                         q->memory_limit) ||
 556             nla_put_u32(skb, TCA_FQ_CODEL_FLOWS,
 557                         q->flows_cnt))
 558                 goto nla_put_failure;
 559
 560         if (q->cparams.ce_threshold != CODEL_DISABLED_THRESHOLD &&
 561             nla_put_u32(skb, TCA_FQ_CODEL_CE_THRESHOLD,
 562                         codel_time_to_us(q->cparams.ce_threshold)))
 563                 goto nla_put_failure;
 564
 565         return nla_nest_end(skb, opts);
 566
 567 nla_put_failure:
 568         return -1;
 569 }
 570
 571 static int fq_codel_dump_stats(struct Qdisc *sch, struct gnet_dump *d)
 572 {
 573         struct fq_codel_sched_data *q = qdisc_priv(sch);
 574         struct tc_fq_codel_xstats st = {
 575                 .type                           = TCA_FQ_CODEL_XSTATS_QDISC,
 576         };
 577         struct list_head *pos;
 578
 579         st.qdisc_stats.maxpacket = q->cstats.maxpacket;
 580         st.qdisc_stats.drop_overlimit = q->drop_overlimit;
 581         st.qdisc_stats.ecn_mark = q->cstats.ecn_mark;
 582         st.qdisc_stats.new_flow_count = q->new_flow_count;
 583         st.qdisc_stats.ce_mark = q->cstats.ce_mark;
 584         st.qdisc_stats.memory_usage  = q->memory_usage;
 585         st.qdisc_stats.drop_overmemory = q->drop_overmemory;
 586
 587         sch_tree_lock(sch);
 588         list_for_each(pos, &q->new_flows)
 589                 st.qdisc_stats.new_flows_len++;
 590
 591         list_for_each(pos, &q->old_flows)
 592                 st.qdisc_stats.old_flows_len++;
 593         sch_tree_unlock(sch);
 594
 595         return gnet_stats_copy_app(d, &st, sizeof(st));
 596 }
 597
 598 static struct Qdisc *fq_codel_leaf(struct Qdisc *sch, unsigned long arg)
 599 {
 600         return NULL;
 601 }
 602
 603 static unsigned long fq_codel_find(struct Qdisc *sch, u32 classid)
 604 {
 605         return 0;
 606 }
 607
 608 static unsigned long fq_codel_bind(struct Qdisc *sch, unsigned long parent,
 609                               u32 classid)
 610 {
 611         return 0;
 612 }
 613
 614 static void fq_codel_unbind(struct Qdisc *q, unsigned long cl)
 615 {
 616 }
 617
 618 static struct tcf_block *fq_codel_tcf_block(struct Qdisc *sch, unsigned long cl,
 619                                             struct netlink_ext_ack *extack)
 620 {
 621         struct fq_codel_sched_data *q = qdisc_priv(sch);
 622
 623         if (cl)
 624                 return NULL;
 625         return q->block;
 626 }
 627
 628 static int fq_codel_dump_class(struct Qdisc *sch, unsigned long cl,
 629                           struct sk_buff *skb, struct tcmsg *tcm)
 630 {
 631         tcm->tcm_handle |= TC_H_MIN(cl);
 632         return 0;
 633 }
 634
 635 static int fq_codel_dump_class_stats(struct Qdisc *sch, unsigned long cl,
 636                                      struct gnet_dump *d)
 637 {
 638         struct fq_codel_sched_data *q = qdisc_priv(sch);
 639         u32 idx = cl - 1;
 640         struct gnet_stats_queue qs = { 0 };
 641         struct tc_fq_codel_xstats xstats;
 642
 643         if (idx < q->flows_cnt) {
 644                 const struct fq_codel_flow *flow = &q->flows[idx];
 645                 const struct sk_buff *skb;
 646
 647                 memset(&xstats, 0, sizeof(xstats));
 648                 xstats.type = TCA_FQ_CODEL_XSTATS_CLASS;
 649                 xstats.class_stats.deficit = flow->deficit;
 650                 xstats.class_stats.ldelay =
 651                         codel_time_to_us(flow->cvars.ldelay);
 652                 xstats.class_stats.count = flow->cvars.count;
 653                 xstats.class_stats.lastcount = flow->cvars.lastcount;
 654                 xstats.class_stats.dropping = flow->cvars.dropping;
 655                 if (flow->cvars.dropping) {
 656                         codel_tdiff_t delta = flow->cvars.drop_next -
 657                                               codel_get_time();
 658
 659                         xstats.class_stats.drop_next = (delta >= 0) ?
 660                                 codel_time_to_us(delta) :
 661                                 -codel_time_to_us(-delta);
 662                 }
 663                 if (flow->head) {
 664                         sch_tree_lock(sch);
 665                         skb = flow->head;
 666                         while (skb) {
 667                                 qs.qlen++;
 668                                 skb = skb->next;
 669                         }
 670                         sch_tree_unlock(sch);
 671                 }
 672                 qs.backlog = q->backlogs[idx];
 673                 qs.drops = flow->dropped;
 674         }
 675         if (gnet_stats_copy_queue(d, NULL, &qs, qs.qlen) < 0)
 676                 return -1;
 677         if (idx < q->flows_cnt)
 678                 return gnet_stats_copy_app(d, &xstats, sizeof(xstats));
 679         return 0;
 680 }
 681
 682 static void fq_codel_walk(struct Qdisc *sch, struct qdisc_walker *arg)
 683 {
 684         struct fq_codel_sched_data *q = qdisc_priv(sch);
 685         unsigned int i;
 686
 687         if (arg->stop)
 688                 return;
 689
 690         for (i = 0; i < q->flows_cnt; i++) {
 691                 if (list_empty(&q->flows[i].flowchain) ||
 692                     arg->count < arg->skip) {
 693                         arg->count++;
 694                         continue;
 695                 }
 696                 if (arg->fn(sch, i + 1, arg) < 0) {
 697                         arg->stop = 1;
 698                         break;
 699                 }
 700                 arg->count++;
 701         }
 702 }
 703
 704 static const struct Qdisc_class_ops fq_codel_class_ops = {
 705         .leaf           =       fq_codel_leaf,
 706         .find           =       fq_codel_find,
 707         .tcf_block      =       fq_codel_tcf_block,
 708         .bind_tcf       =       fq_codel_bind,
 709         .unbind_tcf     =       fq_codel_unbind,
 710         .dump           =       fq_codel_dump_class,
 711         .dump_stats     =       fq_codel_dump_class_stats,
 712         .walk           =       fq_codel_walk,
 713 };
 714
 715 static struct Qdisc_ops fq_codel_qdisc_ops __read_mostly = {
 716         .cl_ops         =       &fq_codel_class_ops,
 717         .id             =       "fq_codel",
 718         .priv_size      =       sizeof(struct fq_codel_sched_data),
 719         .enqueue        =       fq_codel_enqueue,
 720         .dequeue        =       fq_codel_dequeue,
 721         .peek           =       qdisc_peek_dequeued,
 722         .init           =       fq_codel_init,
 723         .reset          =       fq_codel_reset,
 724         .destroy        =       fq_codel_destroy,
 725         .change         =       fq_codel_change,
 726         .dump           =       fq_codel_dump,
 727         .dump_stats =   fq_codel_dump_stats,
 728         .owner          =       THIS_MODULE,
 729 };
 730
 731 static int __init fq_codel_module_init(void)
 732 {
 733         return register_qdisc(&fq_codel_qdisc_ops);
 734 }
 735
 736 static void __exit fq_codel_module_exit(void)
 737 {
 738         unregister_qdisc(&fq_codel_qdisc_ops);
 739 }
 740
 741 module_init(fq_codel_module_init)
 742 module_exit(fq_codel_module_exit)
 743 MODULE_AUTHOR("Eric Dumazet");
 744 MODULE_LICENSE("GPL");