1// SPDX-License-Identifier: GPL-2.0-or-later 2/* 3 * net/sched/sch_fq.c Fair Queue Packet Scheduler (per flow pacing) 4 * 5 * Copyright (C) 2013-2023 Eric Dumazet <edumazet@google.com> 6 * 7 * Meant to be mostly used for locally generated traffic : 8 * Fast classification depends on skb->sk being set before reaching us. 9 * If not, (router workload), we use rxhash as fallback, with 32 bits wide hash. 10 * All packets belonging to a socket are considered as a 'flow'. 11 * 12 * Flows are dynamically allocated and stored in a hash table of RB trees 13 * They are also part of one Round Robin 'queues' (new or old flows) 14 * 15 * Burst avoidance (aka pacing) capability : 16 * 17 * Transport (eg TCP) can set in sk->sk_pacing_rate a rate, enqueue a 18 * bunch of packets, and this packet scheduler adds delay between 19 * packets to respect rate limitation. 20 * 21 * enqueue() : 22 * - lookup one RB tree (out of 1024 or more) to find the flow. 23 * If non existent flow, create it, add it to the tree. 24 * Add skb to the per flow list of skb (fifo). 25 * - Use a special fifo for high prio packets 26 * 27 * dequeue() : serves flows in Round Robin 28 * Note : When a flow becomes empty, we do not immediately remove it from 29 * rb trees, for performance reasons (its expected to send additional packets, 30 * or SLAB cache will reuse socket for another flow) 31 */ 32 33#include <linux/module.h> 34#include <linux/types.h> 35#include <linux/kernel.h> 36#include <linux/jiffies.h> 37#include <linux/string.h> 38#include <linux/in.h> 39#include <linux/errno.h> 40#include <linux/init.h> 41#include <linux/skbuff.h> 42#include <linux/slab.h> 43#include <linux/rbtree.h> 44#include <linux/hash.h> 45#include <linux/prefetch.h> 46#include <linux/vmalloc.h> 47#include <net/netlink.h> 48#include <net/pkt_sched.h> 49#include <net/sock.h> 50#include <net/tcp_states.h> 51#include <net/tcp.h> 52 53struct fq_skb_cb { 54 u64 time_to_send; 55 u8 band; 56}; 57 58static inline struct fq_skb_cb *fq_skb_cb(struct sk_buff *skb) 59{ 60 qdisc_cb_private_validate(skb, sizeof(struct fq_skb_cb)); 61 return (struct fq_skb_cb *)qdisc_skb_cb(skb)->data; 62} 63 64/* 65 * Per flow structure, dynamically allocated. 66 * If packets have monotically increasing time_to_send, they are placed in O(1) 67 * in linear list (head,tail), otherwise are placed in a rbtree (t_root). 68 */ 69struct fq_flow { 70/* First cache line : used in fq_gc(), fq_enqueue(), fq_dequeue() */ 71 struct rb_root t_root; 72 struct sk_buff *head; /* list of skbs for this flow : first skb */ 73 union { 74 struct sk_buff *tail; /* last skb in the list */ 75 unsigned long age; /* (jiffies | 1UL) when flow was emptied, for gc */ 76 }; 77 union { 78 struct rb_node fq_node; /* anchor in fq_root[] trees */ 79 /* Following field is only used for q->internal, 80 * because q->internal is not hashed in fq_root[] 81 */ 82 u64 stat_fastpath_packets; 83 }; 84 struct sock *sk; 85 u32 socket_hash; /* sk_hash */ 86 int qlen; /* number of packets in flow queue */ 87 88/* Second cache line */ 89 int credit; 90 int band; 91 struct fq_flow *next; /* next pointer in RR lists */ 92 93 struct rb_node rate_node; /* anchor in q->delayed tree */ 94 u64 time_next_packet; 95}; 96 97struct fq_flow_head { 98 struct fq_flow *first; 99 struct fq_flow *last; 100}; 101 102struct fq_perband_flows { 103 struct fq_flow_head new_flows; 104 struct fq_flow_head old_flows; 105 int credit; 106 int quantum; /* based on band nr : 576KB, 192KB, 64KB */ 107}; 108 109struct fq_sched_data { 110/* Read mostly cache line */ 111 112 u32 quantum; 113 u32 initial_quantum; 114 u32 flow_refill_delay; 115 u32 flow_plimit; /* max packets per flow */ 116 unsigned long flow_max_rate; /* optional max rate per flow */ 117 u64 ce_threshold; 118 u64 horizon; /* horizon in ns */ 119 u32 orphan_mask; /* mask for orphaned skb */ 120 u32 low_rate_threshold; 121 struct rb_root *fq_root; 122 u8 rate_enable; 123 u8 fq_trees_log; 124 u8 horizon_drop; 125 u8 prio2band[(TC_PRIO_MAX + 1) >> 2]; 126 u32 timer_slack; /* hrtimer slack in ns */ 127 128/* Read/Write fields. */ 129 130 unsigned int band_nr; /* band being serviced in fq_dequeue() */ 131 132 struct fq_perband_flows band_flows[FQ_BANDS]; 133 134 struct fq_flow internal; /* fastpath queue. */ 135 struct rb_root delayed; /* for rate limited flows */ 136 u64 time_next_delayed_flow; 137 unsigned long unthrottle_latency_ns; 138 139 u32 band_pkt_count[FQ_BANDS]; 140 u32 flows; 141 u32 inactive_flows; /* Flows with no packet to send. */ 142 u32 throttled_flows; 143 144 u64 stat_throttled; 145 struct qdisc_watchdog watchdog; 146 u64 stat_gc_flows; 147 148/* Seldom used fields. */ 149 150 u64 stat_band_drops[FQ_BANDS]; 151 u64 stat_ce_mark; 152 u64 stat_horizon_drops; 153 u64 stat_horizon_caps; 154 u64 stat_flows_plimit; 155 u64 stat_pkts_too_long; 156 u64 stat_allocation_errors; 157}; 158 159/* return the i-th 2-bit value ("crumb") */ 160static u8 fq_prio2band(const u8 *prio2band, unsigned int prio) 161{ 162 return (prio2band[prio / 4] >> (2 * (prio & 0x3))) & 0x3; 163} 164 165/* 166 * f->tail and f->age share the same location. 167 * We can use the low order bit to differentiate if this location points 168 * to a sk_buff or contains a jiffies value, if we force this value to be odd. 169 * This assumes f->tail low order bit must be 0 since alignof(struct sk_buff) >= 2 170 */ 171static void fq_flow_set_detached(struct fq_flow *f) 172{ 173 f->age = jiffies | 1UL; 174} 175 176static bool fq_flow_is_detached(const struct fq_flow *f) 177{ 178 return !!(f->age & 1UL); 179} 180 181/* special value to mark a throttled flow (not on old/new list) */ 182static struct fq_flow throttled; 183 184static bool fq_flow_is_throttled(const struct fq_flow *f) 185{ 186 return f->next == &throttled; 187} 188 189enum new_flow { 190 NEW_FLOW, 191 OLD_FLOW 192}; 193 194static void fq_flow_add_tail(struct fq_sched_data *q, struct fq_flow *flow, 195 enum new_flow list_sel) 196{ 197 struct fq_perband_flows *pband = &q->band_flows[flow->band]; 198 struct fq_flow_head *head = (list_sel == NEW_FLOW) ? 199 &pband->new_flows : 200 &pband->old_flows; 201 202 if (head->first) 203 head->last->next = flow; 204 else 205 head->first = flow; 206 head->last = flow; 207 flow->next = NULL; 208} 209 210static void fq_flow_unset_throttled(struct fq_sched_data *q, struct fq_flow *f) 211{ 212 rb_erase(&f->rate_node, &q->delayed); 213 q->throttled_flows--; 214 fq_flow_add_tail(q, f, OLD_FLOW); 215} 216 217static void fq_flow_set_throttled(struct fq_sched_data *q, struct fq_flow *f) 218{ 219 struct rb_node **p = &q->delayed.rb_node, *parent = NULL; 220 221 while (*p) { 222 struct fq_flow *aux; 223 224 parent = *p; 225 aux = rb_entry(parent, struct fq_flow, rate_node); 226 if (f->time_next_packet >= aux->time_next_packet) 227 p = &parent->rb_right; 228 else 229 p = &parent->rb_left; 230 } 231 rb_link_node(&f->rate_node, parent, p); 232 rb_insert_color(&f->rate_node, &q->delayed); 233 q->throttled_flows++; 234 q->stat_throttled++; 235 236 f->next = &throttled; 237 if (q->time_next_delayed_flow > f->time_next_packet) 238 q->time_next_delayed_flow = f->time_next_packet; 239} 240 241 242static struct kmem_cache *fq_flow_cachep __read_mostly; 243 244 245/* limit number of collected flows per round */ 246#define FQ_GC_MAX 8 247#define FQ_GC_AGE (3*HZ) 248 249static bool fq_gc_candidate(const struct fq_flow *f) 250{ 251 return fq_flow_is_detached(f) && 252 time_after(jiffies, f->age + FQ_GC_AGE); 253} 254 255static void fq_gc(struct fq_sched_data *q, 256 struct rb_root *root, 257 struct sock *sk) 258{ 259 struct rb_node **p, *parent; 260 void *tofree[FQ_GC_MAX]; 261 struct fq_flow *f; 262 int i, fcnt = 0; 263 264 p = &root->rb_node; 265 parent = NULL; 266 while (*p) { 267 parent = *p; 268 269 f = rb_entry(parent, struct fq_flow, fq_node); 270 if (f->sk == sk) 271 break; 272 273 if (fq_gc_candidate(f)) { 274 tofree[fcnt++] = f; 275 if (fcnt == FQ_GC_MAX) 276 break; 277 } 278 279 if (f->sk > sk) 280 p = &parent->rb_right; 281 else 282 p = &parent->rb_left; 283 } 284 285 if (!fcnt) 286 return; 287 288 for (i = fcnt; i > 0; ) { 289 f = tofree[--i]; 290 rb_erase(&f->fq_node, root); 291 } 292 q->flows -= fcnt; 293 q->inactive_flows -= fcnt; 294 q->stat_gc_flows += fcnt; 295 296 kmem_cache_free_bulk(fq_flow_cachep, fcnt, tofree); 297} 298 299/* Fast path can be used if : 300 * 1) Packet tstamp is in the past. 301 * 2) FQ qlen == 0 OR 302 * (no flow is currently eligible for transmit, 303 * AND fast path queue has less than 8 packets) 304 * 3) No SO_MAX_PACING_RATE on the socket (if any). 305 * 4) No @maxrate attribute on this qdisc, 306 * 307 * FQ can not use generic TCQ_F_CAN_BYPASS infrastructure. 308 */ 309static bool fq_fastpath_check(const struct Qdisc *sch, struct sk_buff *skb, 310 u64 now) 311{ 312 const struct fq_sched_data *q = qdisc_priv(sch); 313 const struct sock *sk; 314 315 if (fq_skb_cb(skb)->time_to_send > now) 316 return false; 317 318 if (sch->q.qlen != 0) { 319 /* Even if some packets are stored in this qdisc, 320 * we can still enable fast path if all of them are 321 * scheduled in the future (ie no flows are eligible) 322 * or in the fast path queue. 323 */ 324 if (q->flows != q->inactive_flows + q->throttled_flows) 325 return false; 326 327 /* Do not allow fast path queue to explode, we want Fair Queue mode 328 * under pressure. 329 */ 330 if (q->internal.qlen >= 8) 331 return false; 332 } 333 334 sk = skb->sk; 335 if (sk && sk_fullsock(sk) && !sk_is_tcp(sk) && 336 sk->sk_max_pacing_rate != ~0UL) 337 return false; 338 339 if (q->flow_max_rate != ~0UL) 340 return false; 341 342 return true; 343} 344 345static struct fq_flow *fq_classify(struct Qdisc *sch, struct sk_buff *skb, 346 u64 now) 347{ 348 struct fq_sched_data *q = qdisc_priv(sch); 349 struct rb_node **p, *parent; 350 struct sock *sk = skb->sk; 351 struct rb_root *root; 352 struct fq_flow *f; 353 354 /* SYNACK messages are attached to a TCP_NEW_SYN_RECV request socket 355 * or a listener (SYNCOOKIE mode) 356 * 1) request sockets are not full blown, 357 * they do not contain sk_pacing_rate 358 * 2) They are not part of a 'flow' yet 359 * 3) We do not want to rate limit them (eg SYNFLOOD attack), 360 * especially if the listener set SO_MAX_PACING_RATE 361 * 4) We pretend they are orphaned 362 */ 363 if (!sk || sk_listener(sk)) { 364 unsigned long hash = skb_get_hash(skb) & q->orphan_mask; 365 366 /* By forcing low order bit to 1, we make sure to not 367 * collide with a local flow (socket pointers are word aligned) 368 */ 369 sk = (struct sock *)((hash << 1) | 1UL); 370 skb_orphan(skb); 371 } else if (sk->sk_state == TCP_CLOSE) { 372 unsigned long hash = skb_get_hash(skb) & q->orphan_mask; 373 /* 374 * Sockets in TCP_CLOSE are non connected. 375 * Typical use case is UDP sockets, they can send packets 376 * with sendto() to many different destinations. 377 * We probably could use a generic bit advertising 378 * non connected sockets, instead of sk_state == TCP_CLOSE, 379 * if we care enough. 380 */ 381 sk = (struct sock *)((hash << 1) | 1UL); 382 } 383 384 if (fq_fastpath_check(sch, skb, now)) { 385 q->internal.stat_fastpath_packets++; 386 if (skb->sk == sk && q->rate_enable && 387 READ_ONCE(sk->sk_pacing_status) != SK_PACING_FQ) 388 smp_store_release(&sk->sk_pacing_status, 389 SK_PACING_FQ); 390 return &q->internal; 391 } 392 393 root = &q->fq_root[hash_ptr(sk, q->fq_trees_log)]; 394 395 fq_gc(q, root, sk); 396 397 p = &root->rb_node; 398 parent = NULL; 399 while (*p) { 400 parent = *p; 401 402 f = rb_entry(parent, struct fq_flow, fq_node); 403 if (f->sk == sk) { 404 /* socket might have been reallocated, so check 405 * if its sk_hash is the same. 406 * It not, we need to refill credit with 407 * initial quantum 408 */ 409 if (unlikely(skb->sk == sk && 410 f->socket_hash != sk->sk_hash)) { 411 f->credit = q->initial_quantum; 412 f->socket_hash = sk->sk_hash; 413 if (q->rate_enable) 414 smp_store_release(&sk->sk_pacing_status, 415 SK_PACING_FQ); 416 if (fq_flow_is_throttled(f)) 417 fq_flow_unset_throttled(q, f); 418 f->time_next_packet = 0ULL; 419 } 420 return f; 421 } 422 if (f->sk > sk) 423 p = &parent->rb_right; 424 else 425 p = &parent->rb_left; 426 } 427 428 f = kmem_cache_zalloc(fq_flow_cachep, GFP_ATOMIC | __GFP_NOWARN); 429 if (unlikely(!f)) { 430 q->stat_allocation_errors++; 431 return &q->internal; 432 } 433 /* f->t_root is already zeroed after kmem_cache_zalloc() */ 434 435 fq_flow_set_detached(f); 436 f->sk = sk; 437 if (skb->sk == sk) { 438 f->socket_hash = sk->sk_hash; 439 if (q->rate_enable) 440 smp_store_release(&sk->sk_pacing_status, 441 SK_PACING_FQ); 442 } 443 f->credit = q->initial_quantum; 444 445 rb_link_node(&f->fq_node, parent, p); 446 rb_insert_color(&f->fq_node, root); 447 448 q->flows++; 449 q->inactive_flows++; 450 return f; 451} 452 453static struct sk_buff *fq_peek(struct fq_flow *flow) 454{ 455 struct sk_buff *skb = skb_rb_first(&flow->t_root); 456 struct sk_buff *head = flow->head; 457 458 if (!skb) 459 return head; 460 461 if (!head) 462 return skb; 463 464 if (fq_skb_cb(skb)->time_to_send < fq_skb_cb(head)->time_to_send) 465 return skb; 466 return head; 467} 468 469static void fq_erase_head(struct Qdisc *sch, struct fq_flow *flow, 470 struct sk_buff *skb) 471{ 472 if (skb == flow->head) { 473 flow->head = skb->next; 474 } else { 475 rb_erase(&skb->rbnode, &flow->t_root); 476 skb->dev = qdisc_dev(sch); 477 } 478} 479 480/* Remove one skb from flow queue. 481 * This skb must be the return value of prior fq_peek(). 482 */ 483static void fq_dequeue_skb(struct Qdisc *sch, struct fq_flow *flow, 484 struct sk_buff *skb) 485{ 486 fq_erase_head(sch, flow, skb); 487 skb_mark_not_on_list(skb); 488 qdisc_qstats_backlog_dec(sch, skb); 489 sch->q.qlen--; 490} 491 492static void flow_queue_add(struct fq_flow *flow, struct sk_buff *skb) 493{ 494 struct rb_node **p, *parent; 495 struct sk_buff *head, *aux; 496 497 head = flow->head; 498 if (!head || 499 fq_skb_cb(skb)->time_to_send >= fq_skb_cb(flow->tail)->time_to_send) { 500 if (!head) 501 flow->head = skb; 502 else 503 flow->tail->next = skb; 504 flow->tail = skb; 505 skb->next = NULL; 506 return; 507 } 508 509 p = &flow->t_root.rb_node; 510 parent = NULL; 511 512 while (*p) { 513 parent = *p; 514 aux = rb_to_skb(parent); 515 if (fq_skb_cb(skb)->time_to_send >= fq_skb_cb(aux)->time_to_send) 516 p = &parent->rb_right; 517 else 518 p = &parent->rb_left; 519 } 520 rb_link_node(&skb->rbnode, parent, p); 521 rb_insert_color(&skb->rbnode, &flow->t_root); 522} 523 524static bool fq_packet_beyond_horizon(const struct sk_buff *skb, 525 const struct fq_sched_data *q, u64 now) 526{ 527 return unlikely((s64)skb->tstamp > (s64)(now + q->horizon)); 528} 529 530static int fq_enqueue(struct sk_buff *skb, struct Qdisc *sch, 531 struct sk_buff **to_free) 532{ 533 struct fq_sched_data *q = qdisc_priv(sch); 534 struct fq_flow *f; 535 u64 now; 536 u8 band; 537 538 band = fq_prio2band(q->prio2band, skb->priority & TC_PRIO_MAX); 539 if (unlikely(q->band_pkt_count[band] >= sch->limit)) { 540 q->stat_band_drops[band]++; 541 return qdisc_drop(skb, sch, to_free); 542 } 543 544 now = ktime_get_ns(); 545 if (!skb->tstamp) { 546 fq_skb_cb(skb)->time_to_send = now; 547 } else { 548 /* Check if packet timestamp is too far in the future. */ 549 if (fq_packet_beyond_horizon(skb, q, now)) { 550 if (q->horizon_drop) { 551 q->stat_horizon_drops++; 552 return qdisc_drop(skb, sch, to_free); 553 } 554 q->stat_horizon_caps++; 555 skb->tstamp = now + q->horizon; 556 } 557 fq_skb_cb(skb)->time_to_send = skb->tstamp; 558 } 559 560 f = fq_classify(sch, skb, now); 561 562 if (f != &q->internal) { 563 if (unlikely(f->qlen >= q->flow_plimit)) { 564 q->stat_flows_plimit++; 565 return qdisc_drop(skb, sch, to_free); 566 } 567 568 if (fq_flow_is_detached(f)) { 569 fq_flow_add_tail(q, f, NEW_FLOW); 570 if (time_after(jiffies, f->age + q->flow_refill_delay)) 571 f->credit = max_t(u32, f->credit, q->quantum); 572 } 573 574 f->band = band; 575 q->band_pkt_count[band]++; 576 fq_skb_cb(skb)->band = band; 577 if (f->qlen == 0) 578 q->inactive_flows--; 579 } 580 581 f->qlen++; 582 /* Note: this overwrites f->age */ 583 flow_queue_add(f, skb); 584 585 qdisc_qstats_backlog_inc(sch, skb); 586 sch->q.qlen++; 587 588 return NET_XMIT_SUCCESS; 589} 590 591static void fq_check_throttled(struct fq_sched_data *q, u64 now) 592{ 593 unsigned long sample; 594 struct rb_node *p; 595 596 if (q->time_next_delayed_flow > now) 597 return; 598 599 /* Update unthrottle latency EWMA. 600 * This is cheap and can help diagnosing timer/latency problems. 601 */ 602 sample = (unsigned long)(now - q->time_next_delayed_flow); 603 q->unthrottle_latency_ns -= q->unthrottle_latency_ns >> 3; 604 q->unthrottle_latency_ns += sample >> 3; 605 606 q->time_next_delayed_flow = ~0ULL; 607 while ((p = rb_first(&q->delayed)) != NULL) { 608 struct fq_flow *f = rb_entry(p, struct fq_flow, rate_node); 609 610 if (f->time_next_packet > now) { 611 q->time_next_delayed_flow = f->time_next_packet; 612 break; 613 } 614 fq_flow_unset_throttled(q, f); 615 } 616} 617 618static struct fq_flow_head *fq_pband_head_select(struct fq_perband_flows *pband) 619{ 620 if (pband->credit <= 0) 621 return NULL; 622 623 if (pband->new_flows.first) 624 return &pband->new_flows; 625 626 return pband->old_flows.first ? &pband->old_flows : NULL; 627} 628 629static struct sk_buff *fq_dequeue(struct Qdisc *sch) 630{ 631 struct fq_sched_data *q = qdisc_priv(sch); 632 struct fq_perband_flows *pband; 633 struct fq_flow_head *head; 634 struct sk_buff *skb; 635 struct fq_flow *f; 636 unsigned long rate; 637 int retry; 638 u32 plen; 639 u64 now; 640 641 if (!sch->q.qlen) 642 return NULL; 643 644 skb = fq_peek(&q->internal); 645 if (unlikely(skb)) { 646 q->internal.qlen--; 647 fq_dequeue_skb(sch, &q->internal, skb); 648 goto out; 649 } 650 651 now = ktime_get_ns(); 652 fq_check_throttled(q, now); 653 retry = 0; 654 pband = &q->band_flows[q->band_nr]; 655begin: 656 head = fq_pband_head_select(pband); 657 if (!head) { 658 while (++retry <= FQ_BANDS) { 659 if (++q->band_nr == FQ_BANDS) 660 q->band_nr = 0; 661 pband = &q->band_flows[q->band_nr]; 662 pband->credit = min(pband->credit + pband->quantum, 663 pband->quantum); 664 goto begin; 665 } 666 if (q->time_next_delayed_flow != ~0ULL) 667 qdisc_watchdog_schedule_range_ns(&q->watchdog, 668 q->time_next_delayed_flow, 669 q->timer_slack); 670 return NULL; 671 } 672 f = head->first; 673 retry = 0; 674 if (f->credit <= 0) { 675 f->credit += q->quantum; 676 head->first = f->next; 677 fq_flow_add_tail(q, f, OLD_FLOW); 678 goto begin; 679 } 680 681 skb = fq_peek(f); 682 if (skb) { 683 u64 time_next_packet = max_t(u64, fq_skb_cb(skb)->time_to_send, 684 f->time_next_packet); 685 686 if (now < time_next_packet) { 687 head->first = f->next; 688 f->time_next_packet = time_next_packet; 689 fq_flow_set_throttled(q, f); 690 goto begin; 691 } 692 prefetch(&skb->end); 693 if ((s64)(now - time_next_packet - q->ce_threshold) > 0) { 694 INET_ECN_set_ce(skb); 695 q->stat_ce_mark++; 696 } 697 if (--f->qlen == 0) 698 q->inactive_flows++; 699 q->band_pkt_count[fq_skb_cb(skb)->band]--; 700 fq_dequeue_skb(sch, f, skb); 701 } else { 702 head->first = f->next; 703 /* force a pass through old_flows to prevent starvation */ 704 if (head == &pband->new_flows) { 705 fq_flow_add_tail(q, f, OLD_FLOW); 706 } else { 707 fq_flow_set_detached(f); 708 } 709 goto begin; 710 } 711 plen = qdisc_pkt_len(skb); 712 f->credit -= plen; 713 pband->credit -= plen; 714 715 if (!q->rate_enable) 716 goto out; 717 718 rate = q->flow_max_rate; 719 720 /* If EDT time was provided for this skb, we need to 721 * update f->time_next_packet only if this qdisc enforces 722 * a flow max rate. 723 */ 724 if (!skb->tstamp) { 725 if (skb->sk) 726 rate = min(READ_ONCE(skb->sk->sk_pacing_rate), rate); 727 728 if (rate <= q->low_rate_threshold) { 729 f->credit = 0; 730 } else { 731 plen = max(plen, q->quantum); 732 if (f->credit > 0) 733 goto out; 734 } 735 } 736 if (rate != ~0UL) { 737 u64 len = (u64)plen * NSEC_PER_SEC; 738 739 if (likely(rate)) 740 len = div64_ul(len, rate); 741 /* Since socket rate can change later, 742 * clamp the delay to 1 second. 743 * Really, providers of too big packets should be fixed ! 744 */ 745 if (unlikely(len > NSEC_PER_SEC)) { 746 len = NSEC_PER_SEC; 747 q->stat_pkts_too_long++; 748 } 749 /* Account for schedule/timers drifts. 750 * f->time_next_packet was set when prior packet was sent, 751 * and current time (@now) can be too late by tens of us. 752 */ 753 if (f->time_next_packet) 754 len -= min(len/2, now - f->time_next_packet); 755 f->time_next_packet = now + len; 756 } 757out: 758 qdisc_bstats_update(sch, skb); 759 return skb; 760} 761 762static void fq_flow_purge(struct fq_flow *flow) 763{ 764 struct rb_node *p = rb_first(&flow->t_root); 765 766 while (p) { 767 struct sk_buff *skb = rb_to_skb(p); 768 769 p = rb_next(p); 770 rb_erase(&skb->rbnode, &flow->t_root); 771 rtnl_kfree_skbs(skb, skb); 772 } 773 rtnl_kfree_skbs(flow->head, flow->tail); 774 flow->head = NULL; 775 flow->qlen = 0; 776} 777 778static void fq_reset(struct Qdisc *sch) 779{ 780 struct fq_sched_data *q = qdisc_priv(sch); 781 struct rb_root *root; 782 struct rb_node *p; 783 struct fq_flow *f; 784 unsigned int idx; 785 786 sch->q.qlen = 0; 787 sch->qstats.backlog = 0; 788 789 fq_flow_purge(&q->internal); 790 791 if (!q->fq_root) 792 return; 793 794 for (idx = 0; idx < (1U << q->fq_trees_log); idx++) { 795 root = &q->fq_root[idx]; 796 while ((p = rb_first(root)) != NULL) { 797 f = rb_entry(p, struct fq_flow, fq_node); 798 rb_erase(p, root); 799 800 fq_flow_purge(f); 801 802 kmem_cache_free(fq_flow_cachep, f); 803 } 804 } 805 for (idx = 0; idx < FQ_BANDS; idx++) { 806 q->band_flows[idx].new_flows.first = NULL; 807 q->band_flows[idx].old_flows.first = NULL; 808 } 809 q->delayed = RB_ROOT; 810 q->flows = 0; 811 q->inactive_flows = 0; 812 q->throttled_flows = 0; 813} 814 815static void fq_rehash(struct fq_sched_data *q, 816 struct rb_root *old_array, u32 old_log, 817 struct rb_root *new_array, u32 new_log) 818{ 819 struct rb_node *op, **np, *parent; 820 struct rb_root *oroot, *nroot; 821 struct fq_flow *of, *nf; 822 int fcnt = 0; 823 u32 idx; 824 825 for (idx = 0; idx < (1U << old_log); idx++) { 826 oroot = &old_array[idx]; 827 while ((op = rb_first(oroot)) != NULL) { 828 rb_erase(op, oroot); 829 of = rb_entry(op, struct fq_flow, fq_node); 830 if (fq_gc_candidate(of)) { 831 fcnt++; 832 kmem_cache_free(fq_flow_cachep, of); 833 continue; 834 } 835 nroot = &new_array[hash_ptr(of->sk, new_log)]; 836 837 np = &nroot->rb_node; 838 parent = NULL; 839 while (*np) { 840 parent = *np; 841 842 nf = rb_entry(parent, struct fq_flow, fq_node); 843 BUG_ON(nf->sk == of->sk); 844 845 if (nf->sk > of->sk) 846 np = &parent->rb_right; 847 else 848 np = &parent->rb_left; 849 } 850 851 rb_link_node(&of->fq_node, parent, np); 852 rb_insert_color(&of->fq_node, nroot); 853 } 854 } 855 q->flows -= fcnt; 856 q->inactive_flows -= fcnt; 857 q->stat_gc_flows += fcnt; 858} 859 860static void fq_free(void *addr) 861{ 862 kvfree(addr); 863} 864 865static int fq_resize(struct Qdisc *sch, u32 log) 866{ 867 struct fq_sched_data *q = qdisc_priv(sch); 868 struct rb_root *array; 869 void *old_fq_root; 870 u32 idx; 871 872 if (q->fq_root && log == q->fq_trees_log) 873 return 0; 874 875 /* If XPS was setup, we can allocate memory on right NUMA node */ 876 array = kvmalloc_node(sizeof(struct rb_root) << log, GFP_KERNEL | __GFP_RETRY_MAYFAIL, 877 netdev_queue_numa_node_read(sch->dev_queue)); 878 if (!array) 879 return -ENOMEM; 880 881 for (idx = 0; idx < (1U << log); idx++) 882 array[idx] = RB_ROOT; 883 884 sch_tree_lock(sch); 885 886 old_fq_root = q->fq_root; 887 if (old_fq_root) 888 fq_rehash(q, old_fq_root, q->fq_trees_log, array, log); 889 890 q->fq_root = array; 891 q->fq_trees_log = log; 892 893 sch_tree_unlock(sch); 894 895 fq_free(old_fq_root); 896 897 return 0; 898} 899 900static const struct netlink_range_validation iq_range = { 901 .max = INT_MAX, 902}; 903 904static const struct nla_policy fq_policy[TCA_FQ_MAX + 1] = { 905 [TCA_FQ_UNSPEC] = { .strict_start_type = TCA_FQ_TIMER_SLACK }, 906 907 [TCA_FQ_PLIMIT] = { .type = NLA_U32 }, 908 [TCA_FQ_FLOW_PLIMIT] = { .type = NLA_U32 }, 909 [TCA_FQ_QUANTUM] = { .type = NLA_U32 }, 910 [TCA_FQ_INITIAL_QUANTUM] = NLA_POLICY_FULL_RANGE(NLA_U32, &iq_range), 911 [TCA_FQ_RATE_ENABLE] = { .type = NLA_U32 }, 912 [TCA_FQ_FLOW_DEFAULT_RATE] = { .type = NLA_U32 }, 913 [TCA_FQ_FLOW_MAX_RATE] = { .type = NLA_U32 }, 914 [TCA_FQ_BUCKETS_LOG] = { .type = NLA_U32 }, 915 [TCA_FQ_FLOW_REFILL_DELAY] = { .type = NLA_U32 }, 916 [TCA_FQ_ORPHAN_MASK] = { .type = NLA_U32 }, 917 [TCA_FQ_LOW_RATE_THRESHOLD] = { .type = NLA_U32 }, 918 [TCA_FQ_CE_THRESHOLD] = { .type = NLA_U32 }, 919 [TCA_FQ_TIMER_SLACK] = { .type = NLA_U32 }, 920 [TCA_FQ_HORIZON] = { .type = NLA_U32 }, 921 [TCA_FQ_HORIZON_DROP] = { .type = NLA_U8 }, 922 [TCA_FQ_PRIOMAP] = NLA_POLICY_EXACT_LEN(sizeof(struct tc_prio_qopt)), 923 [TCA_FQ_WEIGHTS] = NLA_POLICY_EXACT_LEN(FQ_BANDS * sizeof(s32)), 924}; 925 926/* compress a u8 array with all elems <= 3 to an array of 2-bit fields */ 927static void fq_prio2band_compress_crumb(const u8 *in, u8 *out) 928{ 929 const int num_elems = TC_PRIO_MAX + 1; 930 int i; 931 932 memset(out, 0, num_elems / 4); 933 for (i = 0; i < num_elems; i++) 934 out[i / 4] |= in[i] << (2 * (i & 0x3)); 935} 936 937static void fq_prio2band_decompress_crumb(const u8 *in, u8 *out) 938{ 939 const int num_elems = TC_PRIO_MAX + 1; 940 int i; 941 942 for (i = 0; i < num_elems; i++) 943 out[i] = fq_prio2band(in, i); 944} 945 946static int fq_load_weights(struct fq_sched_data *q, 947 const struct nlattr *attr, 948 struct netlink_ext_ack *extack) 949{ 950 s32 *weights = nla_data(attr); 951 int i; 952 953 for (i = 0; i < FQ_BANDS; i++) { 954 if (weights[i] < FQ_MIN_WEIGHT) { 955 NL_SET_ERR_MSG_FMT_MOD(extack, "Weight %d less that minimum allowed %d", 956 weights[i], FQ_MIN_WEIGHT); 957 return -EINVAL; 958 } 959 } 960 for (i = 0; i < FQ_BANDS; i++) 961 q->band_flows[i].quantum = weights[i]; 962 return 0; 963} 964 965static int fq_load_priomap(struct fq_sched_data *q, 966 const struct nlattr *attr, 967 struct netlink_ext_ack *extack) 968{ 969 const struct tc_prio_qopt *map = nla_data(attr); 970 int i; 971 972 if (map->bands != FQ_BANDS) { 973 NL_SET_ERR_MSG_MOD(extack, "FQ only supports 3 bands"); 974 return -EINVAL; 975 } 976 for (i = 0; i < TC_PRIO_MAX + 1; i++) { 977 if (map->priomap[i] >= FQ_BANDS) { 978 NL_SET_ERR_MSG_FMT_MOD(extack, "FQ priomap field %d maps to a too high band %d", 979 i, map->priomap[i]); 980 return -EINVAL; 981 } 982 } 983 fq_prio2band_compress_crumb(map->priomap, q->prio2band); 984 return 0; 985} 986 987static int fq_change(struct Qdisc *sch, struct nlattr *opt, 988 struct netlink_ext_ack *extack) 989{ 990 struct fq_sched_data *q = qdisc_priv(sch); 991 struct nlattr *tb[TCA_FQ_MAX + 1]; 992 int err, drop_count = 0; 993 unsigned drop_len = 0; 994 u32 fq_log; 995 996 err = nla_parse_nested_deprecated(tb, TCA_FQ_MAX, opt, fq_policy, 997 NULL); 998 if (err < 0) 999 return err; 1000 1001 sch_tree_lock(sch); 1002 1003 fq_log = q->fq_trees_log; 1004 1005 if (tb[TCA_FQ_BUCKETS_LOG]) { 1006 u32 nval = nla_get_u32(tb[TCA_FQ_BUCKETS_LOG]); 1007 1008 if (nval >= 1 && nval <= ilog2(256*1024)) 1009 fq_log = nval; 1010 else 1011 err = -EINVAL; 1012 } 1013 if (tb[TCA_FQ_PLIMIT]) 1014 sch->limit = nla_get_u32(tb[TCA_FQ_PLIMIT]); 1015 1016 if (tb[TCA_FQ_FLOW_PLIMIT]) 1017 q->flow_plimit = nla_get_u32(tb[TCA_FQ_FLOW_PLIMIT]); 1018 1019 if (tb[TCA_FQ_QUANTUM]) { 1020 u32 quantum = nla_get_u32(tb[TCA_FQ_QUANTUM]); 1021 1022 if (quantum > 0 && quantum <= (1 << 20)) { 1023 q->quantum = quantum; 1024 } else { 1025 NL_SET_ERR_MSG_MOD(extack, "invalid quantum"); 1026 err = -EINVAL; 1027 } 1028 } 1029 1030 if (tb[TCA_FQ_INITIAL_QUANTUM]) 1031 q->initial_quantum = nla_get_u32(tb[TCA_FQ_INITIAL_QUANTUM]); 1032 1033 if (tb[TCA_FQ_FLOW_DEFAULT_RATE]) 1034 pr_warn_ratelimited("sch_fq: defrate %u ignored.\n", 1035 nla_get_u32(tb[TCA_FQ_FLOW_DEFAULT_RATE])); 1036 1037 if (tb[TCA_FQ_FLOW_MAX_RATE]) { 1038 u32 rate = nla_get_u32(tb[TCA_FQ_FLOW_MAX_RATE]); 1039 1040 q->flow_max_rate = (rate == ~0U) ? ~0UL : rate; 1041 } 1042 if (tb[TCA_FQ_LOW_RATE_THRESHOLD]) 1043 q->low_rate_threshold = 1044 nla_get_u32(tb[TCA_FQ_LOW_RATE_THRESHOLD]); 1045 1046 if (tb[TCA_FQ_RATE_ENABLE]) { 1047 u32 enable = nla_get_u32(tb[TCA_FQ_RATE_ENABLE]); 1048 1049 if (enable <= 1) 1050 q->rate_enable = enable; 1051 else 1052 err = -EINVAL; 1053 } 1054 1055 if (tb[TCA_FQ_FLOW_REFILL_DELAY]) { 1056 u32 usecs_delay = nla_get_u32(tb[TCA_FQ_FLOW_REFILL_DELAY]) ; 1057 1058 q->flow_refill_delay = usecs_to_jiffies(usecs_delay); 1059 } 1060 1061 if (!err && tb[TCA_FQ_PRIOMAP]) 1062 err = fq_load_priomap(q, tb[TCA_FQ_PRIOMAP], extack); 1063 1064 if (!err && tb[TCA_FQ_WEIGHTS]) 1065 err = fq_load_weights(q, tb[TCA_FQ_WEIGHTS], extack); 1066 1067 if (tb[TCA_FQ_ORPHAN_MASK]) 1068 q->orphan_mask = nla_get_u32(tb[TCA_FQ_ORPHAN_MASK]); 1069 1070 if (tb[TCA_FQ_CE_THRESHOLD]) 1071 q->ce_threshold = (u64)NSEC_PER_USEC * 1072 nla_get_u32(tb[TCA_FQ_CE_THRESHOLD]); 1073 1074 if (tb[TCA_FQ_TIMER_SLACK]) 1075 q->timer_slack = nla_get_u32(tb[TCA_FQ_TIMER_SLACK]); 1076 1077 if (tb[TCA_FQ_HORIZON]) 1078 q->horizon = (u64)NSEC_PER_USEC * 1079 nla_get_u32(tb[TCA_FQ_HORIZON]); 1080 1081 if (tb[TCA_FQ_HORIZON_DROP]) 1082 q->horizon_drop = nla_get_u8(tb[TCA_FQ_HORIZON_DROP]); 1083 1084 if (!err) { 1085 1086 sch_tree_unlock(sch); 1087 err = fq_resize(sch, fq_log); 1088 sch_tree_lock(sch); 1089 } 1090 while (sch->q.qlen > sch->limit) { 1091 struct sk_buff *skb = fq_dequeue(sch); 1092 1093 if (!skb) 1094 break; 1095 drop_len += qdisc_pkt_len(skb); 1096 rtnl_kfree_skbs(skb, skb); 1097 drop_count++; 1098 } 1099 qdisc_tree_reduce_backlog(sch, drop_count, drop_len); 1100 1101 sch_tree_unlock(sch); 1102 return err; 1103} 1104 1105static void fq_destroy(struct Qdisc *sch) 1106{ 1107 struct fq_sched_data *q = qdisc_priv(sch); 1108 1109 fq_reset(sch); 1110 fq_free(q->fq_root); 1111 qdisc_watchdog_cancel(&q->watchdog); 1112} 1113 1114static int fq_init(struct Qdisc *sch, struct nlattr *opt, 1115 struct netlink_ext_ack *extack) 1116{ 1117 struct fq_sched_data *q = qdisc_priv(sch); 1118 int i, err; 1119 1120 sch->limit = 10000; 1121 q->flow_plimit = 100; 1122 q->quantum = 2 * psched_mtu(qdisc_dev(sch)); 1123 q->initial_quantum = 10 * psched_mtu(qdisc_dev(sch)); 1124 q->flow_refill_delay = msecs_to_jiffies(40); 1125 q->flow_max_rate = ~0UL; 1126 q->time_next_delayed_flow = ~0ULL; 1127 q->rate_enable = 1; 1128 for (i = 0; i < FQ_BANDS; i++) { 1129 q->band_flows[i].new_flows.first = NULL; 1130 q->band_flows[i].old_flows.first = NULL; 1131 } 1132 q->band_flows[0].quantum = 9 << 16; 1133 q->band_flows[1].quantum = 3 << 16; 1134 q->band_flows[2].quantum = 1 << 16; 1135 q->delayed = RB_ROOT; 1136 q->fq_root = NULL; 1137 q->fq_trees_log = ilog2(1024); 1138 q->orphan_mask = 1024 - 1; 1139 q->low_rate_threshold = 550000 / 8; 1140 1141 q->timer_slack = 10 * NSEC_PER_USEC; /* 10 usec of hrtimer slack */ 1142 1143 q->horizon = 10ULL * NSEC_PER_SEC; /* 10 seconds */ 1144 q->horizon_drop = 1; /* by default, drop packets beyond horizon */ 1145 1146 /* Default ce_threshold of 4294 seconds */ 1147 q->ce_threshold = (u64)NSEC_PER_USEC * ~0U; 1148 1149 fq_prio2band_compress_crumb(sch_default_prio2band, q->prio2band); 1150 qdisc_watchdog_init_clockid(&q->watchdog, sch, CLOCK_MONOTONIC); 1151 1152 if (opt) 1153 err = fq_change(sch, opt, extack); 1154 else 1155 err = fq_resize(sch, q->fq_trees_log); 1156 1157 return err; 1158} 1159 1160static int fq_dump(struct Qdisc *sch, struct sk_buff *skb) 1161{ 1162 struct fq_sched_data *q = qdisc_priv(sch); 1163 u64 ce_threshold = q->ce_threshold; 1164 struct tc_prio_qopt prio = { 1165 .bands = FQ_BANDS, 1166 }; 1167 u64 horizon = q->horizon; 1168 struct nlattr *opts; 1169 s32 weights[3]; 1170 1171 opts = nla_nest_start_noflag(skb, TCA_OPTIONS); 1172 if (opts == NULL) 1173 goto nla_put_failure; 1174 1175 /* TCA_FQ_FLOW_DEFAULT_RATE is not used anymore */ 1176 1177 do_div(ce_threshold, NSEC_PER_USEC); 1178 do_div(horizon, NSEC_PER_USEC); 1179 1180 if (nla_put_u32(skb, TCA_FQ_PLIMIT, sch->limit) || 1181 nla_put_u32(skb, TCA_FQ_FLOW_PLIMIT, q->flow_plimit) || 1182 nla_put_u32(skb, TCA_FQ_QUANTUM, q->quantum) || 1183 nla_put_u32(skb, TCA_FQ_INITIAL_QUANTUM, q->initial_quantum) || 1184 nla_put_u32(skb, TCA_FQ_RATE_ENABLE, q->rate_enable) || 1185 nla_put_u32(skb, TCA_FQ_FLOW_MAX_RATE, 1186 min_t(unsigned long, q->flow_max_rate, ~0U)) || 1187 nla_put_u32(skb, TCA_FQ_FLOW_REFILL_DELAY, 1188 jiffies_to_usecs(q->flow_refill_delay)) || 1189 nla_put_u32(skb, TCA_FQ_ORPHAN_MASK, q->orphan_mask) || 1190 nla_put_u32(skb, TCA_FQ_LOW_RATE_THRESHOLD, 1191 q->low_rate_threshold) || 1192 nla_put_u32(skb, TCA_FQ_CE_THRESHOLD, (u32)ce_threshold) || 1193 nla_put_u32(skb, TCA_FQ_BUCKETS_LOG, q->fq_trees_log) || 1194 nla_put_u32(skb, TCA_FQ_TIMER_SLACK, q->timer_slack) || 1195 nla_put_u32(skb, TCA_FQ_HORIZON, (u32)horizon) || 1196 nla_put_u8(skb, TCA_FQ_HORIZON_DROP, q->horizon_drop)) 1197 goto nla_put_failure; 1198 1199 fq_prio2band_decompress_crumb(q->prio2band, prio.priomap); 1200 if (nla_put(skb, TCA_FQ_PRIOMAP, sizeof(prio), &prio)) 1201 goto nla_put_failure; 1202 1203 weights[0] = q->band_flows[0].quantum; 1204 weights[1] = q->band_flows[1].quantum; 1205 weights[2] = q->band_flows[2].quantum; 1206 if (nla_put(skb, TCA_FQ_WEIGHTS, sizeof(weights), &weights)) 1207 goto nla_put_failure; 1208 1209 return nla_nest_end(skb, opts); 1210 1211nla_put_failure: 1212 return -1; 1213} 1214 1215static int fq_dump_stats(struct Qdisc *sch, struct gnet_dump *d) 1216{ 1217 struct fq_sched_data *q = qdisc_priv(sch); 1218 struct tc_fq_qd_stats st; 1219 int i; 1220 1221 st.pad = 0; 1222 1223 sch_tree_lock(sch); 1224 1225 st.gc_flows = q->stat_gc_flows; 1226 st.highprio_packets = 0; 1227 st.fastpath_packets = q->internal.stat_fastpath_packets; 1228 st.tcp_retrans = 0; 1229 st.throttled = q->stat_throttled; 1230 st.flows_plimit = q->stat_flows_plimit; 1231 st.pkts_too_long = q->stat_pkts_too_long; 1232 st.allocation_errors = q->stat_allocation_errors; 1233 st.time_next_delayed_flow = q->time_next_delayed_flow + q->timer_slack - 1234 ktime_get_ns(); 1235 st.flows = q->flows; 1236 st.inactive_flows = q->inactive_flows; 1237 st.throttled_flows = q->throttled_flows; 1238 st.unthrottle_latency_ns = min_t(unsigned long, 1239 q->unthrottle_latency_ns, ~0U); 1240 st.ce_mark = q->stat_ce_mark; 1241 st.horizon_drops = q->stat_horizon_drops; 1242 st.horizon_caps = q->stat_horizon_caps; 1243 for (i = 0; i < FQ_BANDS; i++) { 1244 st.band_drops[i] = q->stat_band_drops[i]; 1245 st.band_pkt_count[i] = q->band_pkt_count[i]; 1246 } 1247 sch_tree_unlock(sch); 1248 1249 return gnet_stats_copy_app(d, &st, sizeof(st)); 1250} 1251 1252static struct Qdisc_ops fq_qdisc_ops __read_mostly = { 1253 .id = "fq", 1254 .priv_size = sizeof(struct fq_sched_data), 1255 1256 .enqueue = fq_enqueue, 1257 .dequeue = fq_dequeue, 1258 .peek = qdisc_peek_dequeued, 1259 .init = fq_init, 1260 .reset = fq_reset, 1261 .destroy = fq_destroy, 1262 .change = fq_change, 1263 .dump = fq_dump, 1264 .dump_stats = fq_dump_stats, 1265 .owner = THIS_MODULE, 1266}; 1267MODULE_ALIAS_NET_SCH("fq"); 1268 1269static int __init fq_module_init(void) 1270{ 1271 int ret; 1272 1273 fq_flow_cachep = kmem_cache_create("fq_flow_cache", 1274 sizeof(struct fq_flow), 1275 0, SLAB_HWCACHE_ALIGN, NULL); 1276 if (!fq_flow_cachep) 1277 return -ENOMEM; 1278 1279 ret = register_qdisc(&fq_qdisc_ops); 1280 if (ret) 1281 kmem_cache_destroy(fq_flow_cachep); 1282 return ret; 1283} 1284 1285static void __exit fq_module_exit(void) 1286{ 1287 unregister_qdisc(&fq_qdisc_ops); 1288 kmem_cache_destroy(fq_flow_cachep); 1289} 1290 1291module_init(fq_module_init) 1292module_exit(fq_module_exit) 1293MODULE_AUTHOR("Eric Dumazet"); 1294MODULE_LICENSE("GPL"); 1295MODULE_DESCRIPTION("Fair Queue Packet Scheduler"); 1296