net/sched/sch_fq_codel.c

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