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                 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                                   struct sk_buff **to_free)
 144 {
 145         struct fq_codel_sched_data *q = qdisc_priv(sch);
 146         struct sk_buff *skb;
 147         unsigned int maxbacklog = 0, idx = 0, i, len;
 148         struct fq_codel_flow *flow;
 149         unsigned int threshold;
 150         unsigned int mem = 0;
 151
 152         /* Queue is full! Find the fat flow and drop packet(s) from it.
 153          * This might sound expensive, but with 1024 flows, we scan
 154          * 4KB of memory, and we dont need to handle a complex tree
 155          * in fast path (packet queue/enqueue) with many cache misses.
 156          * In stress mode, we'll try to drop 64 packets from the flow,
 157          * amortizing this linear lookup to one cache line per drop.
 158          */
 159         for (i = 0; i < q->flows_cnt; i++) {
 160                 if (q->backlogs[i] > maxbacklog) {
 161                         maxbacklog = q->backlogs[i];
 162                         idx = i;
 163                 }
 164         }
 165
 166         /* Our goal is to drop half of this fat flow backlog */
 167         threshold = maxbacklog >> 1;
 168
 169         flow = &q->flows[idx];
 170         len = 0;
 171         i = 0;
 172         do {
 173                 skb = dequeue_head(flow);
 174                 len += qdisc_pkt_len(skb);
 175                 mem += get_codel_cb(skb)->mem_usage;
 176                 __qdisc_drop(skb, to_free);
 177         } while (++i < max_packets && len < threshold);
 178
 179         flow->dropped += i;
 180         q->backlogs[idx] -= len;
 181         q->memory_usage -= mem;
 182         sch->qstats.drops += i;
 183         sch->qstats.backlog -= len;
 184         sch->q.qlen -= i;
 185         return idx;
 186 }
 187
 188 static int fq_codel_enqueue(struct sk_buff *skb, struct Qdisc *sch,
 189                             struct sk_buff **to_free)
 190 {
 191         struct fq_codel_sched_data *q = qdisc_priv(sch);
 192         unsigned int idx, prev_backlog, prev_qlen;
 193         struct fq_codel_flow *flow;
 194         int uninitialized_var(ret);
 195         unsigned int pkt_len;
 196         bool memory_limited;
 197
 198         idx = fq_codel_classify(skb, sch, &ret);
 199         if (idx == 0) {
 200                 if (ret & __NET_XMIT_BYPASS)
 201                         qdisc_qstats_drop(sch);
 202                 __qdisc_drop(skb, to_free);
 203                 return ret;
 204         }
 205         idx--;
 206
 207         codel_set_enqueue_time(skb);
 208         flow = &q->flows[idx];
 209         flow_queue_add(flow, skb);
 210         q->backlogs[idx] += qdisc_pkt_len(skb);
 211         qdisc_qstats_backlog_inc(sch, skb);
 212
 213         if (list_empty(&flow->flowchain)) {
 214                 list_add_tail(&flow->flowchain, &q->new_flows);
 215                 q->new_flow_count++;
 216                 flow->deficit = q->quantum;
 217                 flow->dropped = 0;
 218         }
 219         get_codel_cb(skb)->mem_usage = skb->truesize;
 220         q->memory_usage += get_codel_cb(skb)->mem_usage;
 221         memory_limited = q->memory_usage > q->memory_limit;
 222         if (++sch->q.qlen <= sch->limit && !memory_limited)
 223                 return NET_XMIT_SUCCESS;
 224
 225         prev_backlog = sch->qstats.backlog;
 226         prev_qlen = sch->q.qlen;
 227
 228         /* save this packet length as it might be dropped by fq_codel_drop() */
 229         pkt_len = qdisc_pkt_len(skb);
 230         /* fq_codel_drop() is quite expensive, as it performs a linear search
 231          * in q->backlogs[] to find a fat flow.
 232          * So instead of dropping a single packet, drop half of its backlog
 233          * with a 64 packets limit to not add a too big cpu spike here.
 234          */
 235         ret = fq_codel_drop(sch, q->drop_batch_size, to_free);
 236
 237         prev_qlen -= sch->q.qlen;
 238         prev_backlog -= sch->qstats.backlog;
 239         q->drop_overlimit += prev_qlen;
 240         if (memory_limited)
 241                 q->drop_overmemory += prev_qlen;
 242
 243         /* As we dropped packet(s), better let upper stack know this.
 244          * If we dropped a packet for this flow, return NET_XMIT_CN,
 245          * but in this case, our parents wont increase their backlogs.
 246          */
 247         if (ret == idx) {
 248                 qdisc_tree_reduce_backlog(sch, prev_qlen - 1,
 249                                           prev_backlog - pkt_len);
 250                 return NET_XMIT_CN;
 251         }
 252         qdisc_tree_reduce_backlog(sch, prev_qlen, prev_backlog);
 253         return NET_XMIT_SUCCESS;
 254 }
 255
 256 /* This is the specific function called from codel_dequeue()
 257  * to dequeue a packet from queue. Note: backlog is handled in
 258  * codel, we dont need to reduce it here.
 259  */
 260 static struct sk_buff *dequeue_func(struct codel_vars *vars, void *ctx)
 261 {
 262         struct Qdisc *sch = ctx;
 263         struct fq_codel_sched_data *q = qdisc_priv(sch);
 264         struct fq_codel_flow *flow;
 265         struct sk_buff *skb = NULL;
 266
 267         flow = container_of(vars, struct fq_codel_flow, cvars);
 268         if (flow->head) {
 269                 skb = dequeue_head(flow);
 270                 q->backlogs[flow - q->flows] -= qdisc_pkt_len(skb);
 271                 q->memory_usage -= get_codel_cb(skb)->mem_usage;
 272                 sch->q.qlen--;
 273                 sch->qstats.backlog -= qdisc_pkt_len(skb);
 274         }
 275         return skb;
 276 }
 277
 278 static void drop_func(struct sk_buff *skb, void *ctx)
 279 {
 280         struct Qdisc *sch = ctx;
 281
 282         kfree_skb(skb);
 283         qdisc_qstats_drop(sch);
 284 }
 285
 286 static struct sk_buff *fq_codel_dequeue(struct Qdisc *sch)
 287 {
 288         struct fq_codel_sched_data *q = qdisc_priv(sch);
 289         struct sk_buff *skb;
 290         struct fq_codel_flow *flow;
 291         struct list_head *head;
 292         u32 prev_drop_count, prev_ecn_mark;
 293
 294 begin:
 295         head = &q->new_flows;
 296         if (list_empty(head)) {
 297                 head = &q->old_flows;
 298                 if (list_empty(head))
 299                         return NULL;
 300         }
 301         flow = list_first_entry(head, struct fq_codel_flow, flowchain);
 302
 303         if (flow->deficit <= 0) {
 304                 flow->deficit += q->quantum;
 305                 list_move_tail(&flow->flowchain, &q->old_flows);
 306                 goto begin;
 307         }
 308
 309         prev_drop_count = q->cstats.drop_count;
 310         prev_ecn_mark = q->cstats.ecn_mark;
 311
 312         skb = codel_dequeue(sch, &sch->qstats.backlog, &q->cparams,
 313                             &flow->cvars, &q->cstats, qdisc_pkt_len,
 314                             codel_get_enqueue_time, drop_func, dequeue_func);
 315
 316         flow->dropped += q->cstats.drop_count - prev_drop_count;
 317         flow->dropped += q->cstats.ecn_mark - prev_ecn_mark;
 318
 319         if (!skb) {
 320                 /* force a pass through old_flows to prevent starvation */
 321                 if ((head == &q->new_flows) && !list_empty(&q->old_flows))
 322                         list_move_tail(&flow->flowchain, &q->old_flows);
 323                 else
 324                         list_del_init(&flow->flowchain);
 325                 goto begin;
 326         }
 327         qdisc_bstats_update(sch, skb);
 328         flow->deficit -= qdisc_pkt_len(skb);
 329         /* We cant call qdisc_tree_reduce_backlog() if our qlen is 0,
 330          * or HTB crashes. Defer it for next round.
 331          */
 332         if (q->cstats.drop_count && sch->q.qlen) {
 333                 qdisc_tree_reduce_backlog(sch, q->cstats.drop_count,
 334                                           q->cstats.drop_len);
 335                 q->cstats.drop_count = 0;
 336                 q->cstats.drop_len = 0;
 337         }
 338         return skb;
 339 }
 340
 341 static void fq_codel_flow_purge(struct fq_codel_flow *flow)
 342 {
 343         rtnl_kfree_skbs(flow->head, flow->tail);
 344         flow->head = NULL;
 345 }
 346
 347 static void fq_codel_reset(struct Qdisc *sch)
 348 {
 349         struct fq_codel_sched_data *q = qdisc_priv(sch);
 350         int i;
 351
 352         INIT_LIST_HEAD(&q->new_flows);
 353         INIT_LIST_HEAD(&q->old_flows);
 354         for (i = 0; i < q->flows_cnt; i++) {
 355                 struct fq_codel_flow *flow = q->flows + i;
 356
 357                 fq_codel_flow_purge(flow);
 358                 INIT_LIST_HEAD(&flow->flowchain);
 359                 codel_vars_init(&flow->cvars);
 360         }
 361         memset(q->backlogs, 0, q->flows_cnt * sizeof(u32));
 362         sch->q.qlen = 0;
 363         sch->qstats.backlog = 0;
 364         q->memory_usage = 0;
 365 }
 366
 367 static const struct nla_policy fq_codel_policy[TCA_FQ_CODEL_MAX + 1] = {
 368         [TCA_FQ_CODEL_TARGET]   = { .type = NLA_U32 },
 369         [TCA_FQ_CODEL_LIMIT]    = { .type = NLA_U32 },
 370         [TCA_FQ_CODEL_INTERVAL] = { .type = NLA_U32 },
 371         [TCA_FQ_CODEL_ECN]      = { .type = NLA_U32 },
 372         [TCA_FQ_CODEL_FLOWS]    = { .type = NLA_U32 },
 373         [TCA_FQ_CODEL_QUANTUM]  = { .type = NLA_U32 },
 374         [TCA_FQ_CODEL_CE_THRESHOLD] = { .type = NLA_U32 },
 375         [TCA_FQ_CODEL_DROP_BATCH_SIZE] = { .type = NLA_U32 },
 376         [TCA_FQ_CODEL_MEMORY_LIMIT] = { .type = NLA_U32 },
 377 };
 378
 379 static int fq_codel_change(struct Qdisc *sch, struct nlattr *opt)
 380 {
 381         struct fq_codel_sched_data *q = qdisc_priv(sch);
 382         struct nlattr *tb[TCA_FQ_CODEL_MAX + 1];
 383         int err;
 384
 385         if (!opt)
 386                 return -EINVAL;
 387
 388         err = nla_parse_nested(tb, TCA_FQ_CODEL_MAX, opt, fq_codel_policy,
 389                                NULL);
 390         if (err < 0)
 391                 return err;
 392         if (tb[TCA_FQ_CODEL_FLOWS]) {
 393                 if (q->flows)
 394                         return -EINVAL;
 395                 q->flows_cnt = nla_get_u32(tb[TCA_FQ_CODEL_FLOWS]);
 396                 if (!q->flows_cnt ||
 397                     q->flows_cnt > 65536)
 398                         return -EINVAL;
 399         }
 400         sch_tree_lock(sch);
 401
 402         if (tb[TCA_FQ_CODEL_TARGET]) {
 403                 u64 target = nla_get_u32(tb[TCA_FQ_CODEL_TARGET]);
 404
 405                 q->cparams.target = (target * NSEC_PER_USEC) >> CODEL_SHIFT;
 406         }
 407
 408         if (tb[TCA_FQ_CODEL_CE_THRESHOLD]) {
 409                 u64 val = nla_get_u32(tb[TCA_FQ_CODEL_CE_THRESHOLD]);
 410
 411                 q->cparams.ce_threshold = (val * NSEC_PER_USEC) >> CODEL_SHIFT;
 412         }
 413
 414         if (tb[TCA_FQ_CODEL_INTERVAL]) {
 415                 u64 interval = nla_get_u32(tb[TCA_FQ_CODEL_INTERVAL]);
 416
 417                 q->cparams.interval = (interval * NSEC_PER_USEC) >> CODEL_SHIFT;
 418         }
 419
 420         if (tb[TCA_FQ_CODEL_LIMIT])
 421                 sch->limit = nla_get_u32(tb[TCA_FQ_CODEL_LIMIT]);
 422
 423         if (tb[TCA_FQ_CODEL_ECN])
 424                 q->cparams.ecn = !!nla_get_u32(tb[TCA_FQ_CODEL_ECN]);
 425
 426         if (tb[TCA_FQ_CODEL_QUANTUM])
 427                 q->quantum = max(256U, nla_get_u32(tb[TCA_FQ_CODEL_QUANTUM]));
 428
 429         if (tb[TCA_FQ_CODEL_DROP_BATCH_SIZE])
 430                 q->drop_batch_size = min(1U, nla_get_u32(tb[TCA_FQ_CODEL_DROP_BATCH_SIZE]));
 431
 432         if (tb[TCA_FQ_CODEL_MEMORY_LIMIT])
 433                 q->memory_limit = min(1U << 31, nla_get_u32(tb[TCA_FQ_CODEL_MEMORY_LIMIT]));
 434
 435         while (sch->q.qlen > sch->limit ||
 436                q->memory_usage > q->memory_limit) {
 437                 struct sk_buff *skb = fq_codel_dequeue(sch);
 438
 439                 q->cstats.drop_len += qdisc_pkt_len(skb);
 440                 rtnl_kfree_skbs(skb, skb);
 441                 q->cstats.drop_count++;
 442         }
 443         qdisc_tree_reduce_backlog(sch, q->cstats.drop_count, q->cstats.drop_len);
 444         q->cstats.drop_count = 0;
 445         q->cstats.drop_len = 0;
 446
 447         sch_tree_unlock(sch);
 448         return 0;
 449 }
 450
 451 static void fq_codel_destroy(struct Qdisc *sch)
 452 {
 453         struct fq_codel_sched_data *q = qdisc_priv(sch);
 454
 455         tcf_block_put(q->block);
 456         kvfree(q->backlogs);
 457         kvfree(q->flows);
 458 }
 459
 460 static int fq_codel_init(struct Qdisc *sch, struct nlattr *opt)
 461 {
 462         struct fq_codel_sched_data *q = qdisc_priv(sch);
 463         int i;
 464         int err;
 465
 466         sch->limit = 10*1024;
 467         q->flows_cnt = 1024;
 468         q->memory_limit = 32 << 20; /* 32 MBytes */
 469         q->drop_batch_size = 64;
 470         q->quantum = psched_mtu(qdisc_dev(sch));
 471         INIT_LIST_HEAD(&q->new_flows);
 472         INIT_LIST_HEAD(&q->old_flows);
 473         codel_params_init(&q->cparams);
 474         codel_stats_init(&q->cstats);
 475         q->cparams.ecn = true;
 476         q->cparams.mtu = psched_mtu(qdisc_dev(sch));
 477
 478         if (opt) {
 479                 int err = fq_codel_change(sch, opt);
 480                 if (err)
 481                         return err;
 482         }
 483
 484         err = tcf_block_get(&q->block, &q->filter_list);
 485         if (err)
 486                 return err;
 487
 488         if (!q->flows) {
 489                 q->flows = kvzalloc(q->flows_cnt *
 490                                            sizeof(struct fq_codel_flow), GFP_KERNEL);
 491                 if (!q->flows)
 492                         return -ENOMEM;
 493                 q->backlogs = kvzalloc(q->flows_cnt * sizeof(u32), GFP_KERNEL);
 494                 if (!q->backlogs) {
 495                         kvfree(q->flows);
 496                         return -ENOMEM;
 497                 }
 498                 for (i = 0; i < q->flows_cnt; i++) {
 499                         struct fq_codel_flow *flow = q->flows + i;
 500
 501                         INIT_LIST_HEAD(&flow->flowchain);
 502                         codel_vars_init(&flow->cvars);
 503                 }
 504         }
 505         if (sch->limit >= 1)
 506                 sch->flags |= TCQ_F_CAN_BYPASS;
 507         else
 508                 sch->flags &= ~TCQ_F_CAN_BYPASS;
 509         return 0;
 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(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_get(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         /* we cannot bypass queue discipline anymore */
 591         sch->flags &= ~TCQ_F_CAN_BYPASS;
 592         return 0;
 593 }
 594
 595 static void fq_codel_put(struct Qdisc *q, unsigned long cl)
 596 {
 597 }
 598
 599 static struct tcf_block *fq_codel_tcf_block(struct Qdisc *sch, unsigned long cl)
 600 {
 601         struct fq_codel_sched_data *q = qdisc_priv(sch);
 602
 603         if (cl)
 604                 return NULL;
 605         return q->block;
 606 }
 607
 608 static int fq_codel_dump_class(struct Qdisc *sch, unsigned long cl,
 609                           struct sk_buff *skb, struct tcmsg *tcm)
 610 {
 611         tcm->tcm_handle |= TC_H_MIN(cl);
 612         return 0;
 613 }
 614
 615 static int fq_codel_dump_class_stats(struct Qdisc *sch, unsigned long cl,
 616                                      struct gnet_dump *d)
 617 {
 618         struct fq_codel_sched_data *q = qdisc_priv(sch);
 619         u32 idx = cl - 1;
 620         struct gnet_stats_queue qs = { 0 };
 621         struct tc_fq_codel_xstats xstats;
 622
 623         if (idx < q->flows_cnt) {
 624                 const struct fq_codel_flow *flow = &q->flows[idx];
 625                 const struct sk_buff *skb;
 626
 627                 memset(&xstats, 0, sizeof(xstats));
 628                 xstats.type = TCA_FQ_CODEL_XSTATS_CLASS;
 629                 xstats.class_stats.deficit = flow->deficit;
 630                 xstats.class_stats.ldelay =
 631                         codel_time_to_us(flow->cvars.ldelay);
 632                 xstats.class_stats.count = flow->cvars.count;
 633                 xstats.class_stats.lastcount = flow->cvars.lastcount;
 634                 xstats.class_stats.dropping = flow->cvars.dropping;
 635                 if (flow->cvars.dropping) {
 636                         codel_tdiff_t delta = flow->cvars.drop_next -
 637                                               codel_get_time();
 638
 639                         xstats.class_stats.drop_next = (delta >= 0) ?
 640                                 codel_time_to_us(delta) :
 641                                 -codel_time_to_us(-delta);
 642                 }
 643                 if (flow->head) {
 644                         sch_tree_lock(sch);
 645                         skb = flow->head;
 646                         while (skb) {
 647                                 qs.qlen++;
 648                                 skb = skb->next;
 649                         }
 650                         sch_tree_unlock(sch);
 651                 }
 652                 qs.backlog = q->backlogs[idx];
 653                 qs.drops = flow->dropped;
 654         }
 655         if (gnet_stats_copy_queue(d, NULL, &qs, qs.qlen) < 0)
 656                 return -1;
 657         if (idx < q->flows_cnt)
 658                 return gnet_stats_copy_app(d, &xstats, sizeof(xstats));
 659         return 0;
 660 }
 661
 662 static void fq_codel_walk(struct Qdisc *sch, struct qdisc_walker *arg)
 663 {
 664         struct fq_codel_sched_data *q = qdisc_priv(sch);
 665         unsigned int i;
 666
 667         if (arg->stop)
 668                 return;
 669
 670         for (i = 0; i < q->flows_cnt; i++) {
 671                 if (list_empty(&q->flows[i].flowchain) ||
 672                     arg->count < arg->skip) {
 673                         arg->count++;
 674                         continue;
 675                 }
 676                 if (arg->fn(sch, i + 1, arg) < 0) {
 677                         arg->stop = 1;
 678                         break;
 679                 }
 680                 arg->count++;
 681         }
 682 }
 683
 684 static const struct Qdisc_class_ops fq_codel_class_ops = {
 685         .leaf           =       fq_codel_leaf,
 686         .get            =       fq_codel_get,
 687         .put            =       fq_codel_put,
 688         .tcf_block      =       fq_codel_tcf_block,
 689         .bind_tcf       =       fq_codel_bind,
 690         .unbind_tcf     =       fq_codel_put,
 691         .dump           =       fq_codel_dump_class,
 692         .dump_stats     =       fq_codel_dump_class_stats,
 693         .walk           =       fq_codel_walk,
 694 };
 695
 696 static struct Qdisc_ops fq_codel_qdisc_ops __read_mostly = {
 697         .cl_ops         =       &fq_codel_class_ops,
 698         .id             =       "fq_codel",
 699         .priv_size      =       sizeof(struct fq_codel_sched_data),
 700         .enqueue        =       fq_codel_enqueue,
 701         .dequeue        =       fq_codel_dequeue,
 702         .peek           =       qdisc_peek_dequeued,
 703         .init           =       fq_codel_init,
 704         .reset          =       fq_codel_reset,
 705         .destroy        =       fq_codel_destroy,
 706         .change         =       fq_codel_change,
 707         .dump           =       fq_codel_dump,
 708         .dump_stats =   fq_codel_dump_stats,
 709         .owner          =       THIS_MODULE,
 710 };
 711
 712 static int __init fq_codel_module_init(void)
 713 {
 714         return register_qdisc(&fq_codel_qdisc_ops);
 715 }
 716
 717 static void __exit fq_codel_module_exit(void)
 718 {
 719         unregister_qdisc(&fq_codel_qdisc_ops);
 720 }
 721
 722 module_init(fq_codel_module_init)
 723 module_exit(fq_codel_module_exit)
 724 MODULE_AUTHOR("Eric Dumazet");
 725 MODULE_LICENSE("GPL");