net/sched/sch_generic.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * net/sched/sch_generic.c      Generic packet scheduler routines.
   4  *
   5  * Authors:     Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
   6  *              Jamal Hadi Salim, <hadi@cyberus.ca> 990601
   7  *              - Ingress support
   8  */
   9
  10 #include <linux/bitops.h>
  11 #include <linux/module.h>
  12 #include <linux/types.h>
  13 #include <linux/kernel.h>
  14 #include <linux/sched.h>
  15 #include <linux/string.h>
  16 #include <linux/errno.h>
  17 #include <linux/netdevice.h>
  18 #include <linux/skbuff.h>
  19 #include <linux/rtnetlink.h>
  20 #include <linux/init.h>
  21 #include <linux/rcupdate.h>
  22 #include <linux/list.h>
  23 #include <linux/slab.h>
  24 #include <linux/if_vlan.h>
  25 #include <linux/skb_array.h>
  26 #include <linux/if_macvlan.h>
  27 #include <net/sch_generic.h>
  28 #include <net/pkt_sched.h>
  29 #include <net/dst.h>
  30 #include <trace/events/qdisc.h>
  31 #include <trace/events/net.h>
  32 #include <net/xfrm.h>
  33
  34 /* Qdisc to use by default */
  35 const struct Qdisc_ops *default_qdisc_ops = &pfifo_fast_ops;
  36 EXPORT_SYMBOL(default_qdisc_ops);
  37
  38 /* Main transmission queue. */
  39
  40 /* Modifications to data participating in scheduling must be protected with
  41  * qdisc_lock(qdisc) spinlock.
  42  *
  43  * The idea is the following:
  44  * - enqueue, dequeue are serialized via qdisc root lock
  45  * - ingress filtering is also serialized via qdisc root lock
  46  * - updates to tree and tree walking are only done under the rtnl mutex.
  47  */
  48
  49 #define SKB_XOFF_MAGIC ((struct sk_buff *)1UL)
  50
  51 static inline struct sk_buff *__skb_dequeue_bad_txq(struct Qdisc *q)
  52 {
  53         const struct netdev_queue *txq = q->dev_queue;
  54         spinlock_t *lock = NULL;
  55         struct sk_buff *skb;
  56
  57         if (q->flags & TCQ_F_NOLOCK) {
  58                 lock = qdisc_lock(q);
  59                 spin_lock(lock);
  60         }
  61
  62         skb = skb_peek(&q->skb_bad_txq);
  63         if (skb) {
  64                 /* check the reason of requeuing without tx lock first */
  65                 txq = skb_get_tx_queue(txq->dev, skb);
  66                 if (!netif_xmit_frozen_or_stopped(txq)) {
  67                         skb = __skb_dequeue(&q->skb_bad_txq);
  68                         if (qdisc_is_percpu_stats(q)) {
  69                                 qdisc_qstats_cpu_backlog_dec(q, skb);
  70                                 qdisc_qstats_cpu_qlen_dec(q);
  71                         } else {
  72                                 qdisc_qstats_backlog_dec(q, skb);
  73                                 q->q.qlen--;
  74                         }
  75                 } else {
  76                         skb = SKB_XOFF_MAGIC;
  77                 }
  78         }
  79
  80         if (lock)
  81                 spin_unlock(lock);
  82
  83         return skb;
  84 }
  85
  86 static inline struct sk_buff *qdisc_dequeue_skb_bad_txq(struct Qdisc *q)
  87 {
  88         struct sk_buff *skb = skb_peek(&q->skb_bad_txq);
  89
  90         if (unlikely(skb))
  91                 skb = __skb_dequeue_bad_txq(q);
  92
  93         return skb;
  94 }
  95
  96 static inline void qdisc_enqueue_skb_bad_txq(struct Qdisc *q,
  97                                              struct sk_buff *skb)
  98 {
  99         spinlock_t *lock = NULL;
 100
 101         if (q->flags & TCQ_F_NOLOCK) {
 102                 lock = qdisc_lock(q);
 103                 spin_lock(lock);
 104         }
 105
 106         __skb_queue_tail(&q->skb_bad_txq, skb);
 107
 108         if (qdisc_is_percpu_stats(q)) {
 109                 qdisc_qstats_cpu_backlog_inc(q, skb);
 110                 qdisc_qstats_cpu_qlen_inc(q);
 111         } else {
 112                 qdisc_qstats_backlog_inc(q, skb);
 113                 q->q.qlen++;
 114         }
 115
 116         if (lock)
 117                 spin_unlock(lock);
 118 }
 119
 120 static inline void dev_requeue_skb(struct sk_buff *skb, struct Qdisc *q)
 121 {
 122         spinlock_t *lock = NULL;
 123
 124         if (q->flags & TCQ_F_NOLOCK) {
 125                 lock = qdisc_lock(q);
 126                 spin_lock(lock);
 127         }
 128
 129         while (skb) {
 130                 struct sk_buff *next = skb->next;
 131
 132                 __skb_queue_tail(&q->gso_skb, skb);
 133
 134                 /* it's still part of the queue */
 135                 if (qdisc_is_percpu_stats(q)) {
 136                         qdisc_qstats_cpu_requeues_inc(q);
 137                         qdisc_qstats_cpu_backlog_inc(q, skb);
 138                         qdisc_qstats_cpu_qlen_inc(q);
 139                 } else {
 140                         q->qstats.requeues++;
 141                         qdisc_qstats_backlog_inc(q, skb);
 142                         q->q.qlen++;
 143                 }
 144
 145                 skb = next;
 146         }
 147         if (lock)
 148                 spin_unlock(lock);
 149         __netif_schedule(q);
 150 }
 151
 152 static void try_bulk_dequeue_skb(struct Qdisc *q,
 153                                  struct sk_buff *skb,
 154                                  const struct netdev_queue *txq,
 155                                  int *packets)
 156 {
 157         int bytelimit = qdisc_avail_bulklimit(txq) - skb->len;
 158
 159         while (bytelimit > 0) {
 160                 struct sk_buff *nskb = q->dequeue(q);
 161
 162                 if (!nskb)
 163                         break;
 164
 165                 bytelimit -= nskb->len; /* covers GSO len */
 166                 skb->next = nskb;
 167                 skb = nskb;
 168                 (*packets)++; /* GSO counts as one pkt */
 169         }
 170         skb_mark_not_on_list(skb);
 171 }
 172
 173 /* This variant of try_bulk_dequeue_skb() makes sure
 174  * all skbs in the chain are for the same txq
 175  */
 176 static void try_bulk_dequeue_skb_slow(struct Qdisc *q,
 177                                       struct sk_buff *skb,
 178                                       int *packets)
 179 {
 180         int mapping = skb_get_queue_mapping(skb);
 181         struct sk_buff *nskb;
 182         int cnt = 0;
 183
 184         do {
 185                 nskb = q->dequeue(q);
 186                 if (!nskb)
 187                         break;
 188                 if (unlikely(skb_get_queue_mapping(nskb) != mapping)) {
 189                         qdisc_enqueue_skb_bad_txq(q, nskb);
 190                         break;
 191                 }
 192                 skb->next = nskb;
 193                 skb = nskb;
 194         } while (++cnt < 8);
 195         (*packets) += cnt;
 196         skb_mark_not_on_list(skb);
 197 }
 198
 199 /* Note that dequeue_skb can possibly return a SKB list (via skb->next).
 200  * A requeued skb (via q->gso_skb) can also be a SKB list.
 201  */
 202 static struct sk_buff *dequeue_skb(struct Qdisc *q, bool *validate,
 203                                    int *packets)
 204 {
 205         const struct netdev_queue *txq = q->dev_queue;
 206         struct sk_buff *skb = NULL;
 207
 208         *packets = 1;
 209         if (unlikely(!skb_queue_empty(&q->gso_skb))) {
 210                 spinlock_t *lock = NULL;
 211
 212                 if (q->flags & TCQ_F_NOLOCK) {
 213                         lock = qdisc_lock(q);
 214                         spin_lock(lock);
 215                 }
 216
 217                 skb = skb_peek(&q->gso_skb);
 218
 219                 /* skb may be null if another cpu pulls gso_skb off in between
 220                  * empty check and lock.
 221                  */
 222                 if (!skb) {
 223                         if (lock)
 224                                 spin_unlock(lock);
 225                         goto validate;
 226                 }
 227
 228                 /* skb in gso_skb were already validated */
 229                 *validate = false;
 230                 if (xfrm_offload(skb))
 231                         *validate = true;
 232                 /* check the reason of requeuing without tx lock first */
 233                 txq = skb_get_tx_queue(txq->dev, skb);
 234                 if (!netif_xmit_frozen_or_stopped(txq)) {
 235                         skb = __skb_dequeue(&q->gso_skb);
 236                         if (qdisc_is_percpu_stats(q)) {
 237                                 qdisc_qstats_cpu_backlog_dec(q, skb);
 238                                 qdisc_qstats_cpu_qlen_dec(q);
 239                         } else {
 240                                 qdisc_qstats_backlog_dec(q, skb);
 241                                 q->q.qlen--;
 242                         }
 243                 } else {
 244                         skb = NULL;
 245                 }
 246                 if (lock)
 247                         spin_unlock(lock);
 248                 goto trace;
 249         }
 250 validate:
 251         *validate = true;
 252
 253         if ((q->flags & TCQ_F_ONETXQUEUE) &&
 254             netif_xmit_frozen_or_stopped(txq))
 255                 return skb;
 256
 257         skb = qdisc_dequeue_skb_bad_txq(q);
 258         if (unlikely(skb)) {
 259                 if (skb == SKB_XOFF_MAGIC)
 260                         return NULL;
 261                 goto bulk;
 262         }
 263         skb = q->dequeue(q);
 264         if (skb) {
 265 bulk:
 266                 if (qdisc_may_bulk(q))
 267                         try_bulk_dequeue_skb(q, skb, txq, packets);
 268                 else
 269                         try_bulk_dequeue_skb_slow(q, skb, packets);
 270         }
 271 trace:
 272         trace_qdisc_dequeue(q, txq, *packets, skb);
 273         return skb;
 274 }
 275
 276 /*
 277  * Transmit possibly several skbs, and handle the return status as
 278  * required. Owning running seqcount bit guarantees that
 279  * only one CPU can execute this function.
 280  *
 281  * Returns to the caller:
 282  *                              false  - hardware queue frozen backoff
 283  *                              true   - feel free to send more pkts
 284  */
 285 bool sch_direct_xmit(struct sk_buff *skb, struct Qdisc *q,
 286                      struct net_device *dev, struct netdev_queue *txq,
 287                      spinlock_t *root_lock, bool validate)
 288 {
 289         int ret = NETDEV_TX_BUSY;
 290         bool again = false;
 291
 292         /* And release qdisc */
 293         if (root_lock)
 294                 spin_unlock(root_lock);
 295
 296         /* Note that we validate skb (GSO, checksum, ...) outside of locks */
 297         if (validate)
 298                 skb = validate_xmit_skb_list(skb, dev, &again);
 299
 300 #ifdef CONFIG_XFRM_OFFLOAD
 301         if (unlikely(again)) {
 302                 if (root_lock)
 303                         spin_lock(root_lock);
 304
 305                 dev_requeue_skb(skb, q);
 306                 return false;
 307         }
 308 #endif
 309
 310         if (likely(skb)) {
 311                 HARD_TX_LOCK(dev, txq, smp_processor_id());
 312                 if (!netif_xmit_frozen_or_stopped(txq))
 313                         skb = dev_hard_start_xmit(skb, dev, txq, &ret);
 314
 315                 HARD_TX_UNLOCK(dev, txq);
 316         } else {
 317                 if (root_lock)
 318                         spin_lock(root_lock);
 319                 return true;
 320         }
 321
 322         if (root_lock)
 323                 spin_lock(root_lock);
 324
 325         if (!dev_xmit_complete(ret)) {
 326                 /* Driver returned NETDEV_TX_BUSY - requeue skb */
 327                 if (unlikely(ret != NETDEV_TX_BUSY))
 328                         net_warn_ratelimited("BUG %s code %d qlen %d\n",
 329                                              dev->name, ret, q->q.qlen);
 330
 331                 dev_requeue_skb(skb, q);
 332                 return false;
 333         }
 334
 335         return true;
 336 }
 337
 338 /*
 339  * NOTE: Called under qdisc_lock(q) with locally disabled BH.
 340  *
 341  * running seqcount guarantees only one CPU can process
 342  * this qdisc at a time. qdisc_lock(q) serializes queue accesses for
 343  * this queue.
 344  *
 345  *  netif_tx_lock serializes accesses to device driver.
 346  *
 347  *  qdisc_lock(q) and netif_tx_lock are mutually exclusive,
 348  *  if one is grabbed, another must be free.
 349  *
 350  * Note, that this procedure can be called by a watchdog timer
 351  *
 352  * Returns to the caller:
 353  *                              0  - queue is empty or throttled.
 354  *                              >0 - queue is not empty.
 355  *
 356  */
 357 static inline bool qdisc_restart(struct Qdisc *q, int *packets)
 358 {
 359         spinlock_t *root_lock = NULL;
 360         struct netdev_queue *txq;
 361         struct net_device *dev;
 362         struct sk_buff *skb;
 363         bool validate;
 364
 365         /* Dequeue packet */
 366         skb = dequeue_skb(q, &validate, packets);
 367         if (unlikely(!skb))
 368                 return false;
 369
 370         if (!(q->flags & TCQ_F_NOLOCK))
 371                 root_lock = qdisc_lock(q);
 372
 373         dev = qdisc_dev(q);
 374         txq = skb_get_tx_queue(dev, skb);
 375
 376         return sch_direct_xmit(skb, q, dev, txq, root_lock, validate);
 377 }
 378
 379 void __qdisc_run(struct Qdisc *q)
 380 {
 381         int quota = dev_tx_weight;
 382         int packets;
 383
 384         while (qdisc_restart(q, &packets)) {
 385                 /*
 386                  * Ordered by possible occurrence: Postpone processing if
 387                  * 1. we've exceeded packet quota
 388                  * 2. another process needs the CPU;
 389                  */
 390                 quota -= packets;
 391                 if (quota <= 0 || need_resched()) {
 392                         __netif_schedule(q);
 393                         break;
 394                 }
 395         }
 396 }
 397
 398 unsigned long dev_trans_start(struct net_device *dev)
 399 {
 400         unsigned long val, res;
 401         unsigned int i;
 402
 403         if (is_vlan_dev(dev))
 404                 dev = vlan_dev_real_dev(dev);
 405         else if (netif_is_macvlan(dev))
 406                 dev = macvlan_dev_real_dev(dev);
 407         res = netdev_get_tx_queue(dev, 0)->trans_start;
 408         for (i = 1; i < dev->num_tx_queues; i++) {
 409                 val = netdev_get_tx_queue(dev, i)->trans_start;
 410                 if (val && time_after(val, res))
 411                         res = val;
 412         }
 413
 414         return res;
 415 }
 416 EXPORT_SYMBOL(dev_trans_start);
 417
 418 static void dev_watchdog(struct timer_list *t)
 419 {
 420         struct net_device *dev = from_timer(dev, t, watchdog_timer);
 421
 422         netif_tx_lock(dev);
 423         if (!qdisc_tx_is_noop(dev)) {
 424                 if (netif_device_present(dev) &&
 425                     netif_running(dev) &&
 426                     netif_carrier_ok(dev)) {
 427                         int some_queue_timedout = 0;
 428                         unsigned int i;
 429                         unsigned long trans_start;
 430
 431                         for (i = 0; i < dev->num_tx_queues; i++) {
 432                                 struct netdev_queue *txq;
 433
 434                                 txq = netdev_get_tx_queue(dev, i);
 435                                 trans_start = txq->trans_start;
 436                                 if (netif_xmit_stopped(txq) &&
 437                                     time_after(jiffies, (trans_start +
 438                                                          dev->watchdog_timeo))) {
 439                                         some_queue_timedout = 1;
 440                                         txq->trans_timeout++;
 441                                         break;
 442                                 }
 443                         }
 444
 445                         if (some_queue_timedout) {
 446                                 trace_net_dev_xmit_timeout(dev, i);
 447                                 WARN_ONCE(1, KERN_INFO "NETDEV WATCHDOG: %s (%s): transmit queue %u timed out\n",
 448                                        dev->name, netdev_drivername(dev), i);
 449                                 dev->netdev_ops->ndo_tx_timeout(dev);
 450                         }
 451                         if (!mod_timer(&dev->watchdog_timer,
 452                                        round_jiffies(jiffies +
 453                                                      dev->watchdog_timeo)))
 454                                 dev_hold(dev);
 455                 }
 456         }
 457         netif_tx_unlock(dev);
 458
 459         dev_put(dev);
 460 }
 461
 462 void __netdev_watchdog_up(struct net_device *dev)
 463 {
 464         if (dev->netdev_ops->ndo_tx_timeout) {
 465                 if (dev->watchdog_timeo <= 0)
 466                         dev->watchdog_timeo = 5*HZ;
 467                 if (!mod_timer(&dev->watchdog_timer,
 468                                round_jiffies(jiffies + dev->watchdog_timeo)))
 469                         dev_hold(dev);
 470         }
 471 }
 472
 473 static void dev_watchdog_up(struct net_device *dev)
 474 {
 475         __netdev_watchdog_up(dev);
 476 }
 477
 478 static void dev_watchdog_down(struct net_device *dev)
 479 {
 480         netif_tx_lock_bh(dev);
 481         if (del_timer(&dev->watchdog_timer))
 482                 dev_put(dev);
 483         netif_tx_unlock_bh(dev);
 484 }
 485
 486 /**
 487  *      netif_carrier_on - set carrier
 488  *      @dev: network device
 489  *
 490  * Device has detected acquisition of carrier.
 491  */
 492 void netif_carrier_on(struct net_device *dev)
 493 {
 494         if (test_and_clear_bit(__LINK_STATE_NOCARRIER, &dev->state)) {
 495                 if (dev->reg_state == NETREG_UNINITIALIZED)
 496                         return;
 497                 atomic_inc(&dev->carrier_up_count);
 498                 linkwatch_fire_event(dev);
 499                 if (netif_running(dev))
 500                         __netdev_watchdog_up(dev);
 501         }
 502 }
 503 EXPORT_SYMBOL(netif_carrier_on);
 504
 505 /**
 506  *      netif_carrier_off - clear carrier
 507  *      @dev: network device
 508  *
 509  * Device has detected loss of carrier.
 510  */
 511 void netif_carrier_off(struct net_device *dev)
 512 {
 513         if (!test_and_set_bit(__LINK_STATE_NOCARRIER, &dev->state)) {
 514                 if (dev->reg_state == NETREG_UNINITIALIZED)
 515                         return;
 516                 atomic_inc(&dev->carrier_down_count);
 517                 linkwatch_fire_event(dev);
 518         }
 519 }
 520 EXPORT_SYMBOL(netif_carrier_off);
 521
 522 /* "NOOP" scheduler: the best scheduler, recommended for all interfaces
 523    under all circumstances. It is difficult to invent anything faster or
 524    cheaper.
 525  */
 526
 527 static int noop_enqueue(struct sk_buff *skb, struct Qdisc *qdisc,
 528                         struct sk_buff **to_free)
 529 {
 530         __qdisc_drop(skb, to_free);
 531         return NET_XMIT_CN;
 532 }
 533
 534 static struct sk_buff *noop_dequeue(struct Qdisc *qdisc)
 535 {
 536         return NULL;
 537 }
 538
 539 struct Qdisc_ops noop_qdisc_ops __read_mostly = {
 540         .id             =       "noop",
 541         .priv_size      =       0,
 542         .enqueue        =       noop_enqueue,
 543         .dequeue        =       noop_dequeue,
 544         .peek           =       noop_dequeue,
 545         .owner          =       THIS_MODULE,
 546 };
 547
 548 static struct netdev_queue noop_netdev_queue = {
 549         RCU_POINTER_INITIALIZER(qdisc, &noop_qdisc),
 550         .qdisc_sleeping =       &noop_qdisc,
 551 };
 552
 553 struct Qdisc noop_qdisc = {
 554         .enqueue        =       noop_enqueue,
 555         .dequeue        =       noop_dequeue,
 556         .flags          =       TCQ_F_BUILTIN,
 557         .ops            =       &noop_qdisc_ops,
 558         .q.lock         =       __SPIN_LOCK_UNLOCKED(noop_qdisc.q.lock),
 559         .dev_queue      =       &noop_netdev_queue,
 560         .running        =       SEQCNT_ZERO(noop_qdisc.running),
 561         .busylock       =       __SPIN_LOCK_UNLOCKED(noop_qdisc.busylock),
 562         .gso_skb = {
 563                 .next = (struct sk_buff *)&noop_qdisc.gso_skb,
 564                 .prev = (struct sk_buff *)&noop_qdisc.gso_skb,
 565                 .qlen = 0,
 566                 .lock = __SPIN_LOCK_UNLOCKED(noop_qdisc.gso_skb.lock),
 567         },
 568         .skb_bad_txq = {
 569                 .next = (struct sk_buff *)&noop_qdisc.skb_bad_txq,
 570                 .prev = (struct sk_buff *)&noop_qdisc.skb_bad_txq,
 571                 .qlen = 0,
 572                 .lock = __SPIN_LOCK_UNLOCKED(noop_qdisc.skb_bad_txq.lock),
 573         },
 574 };
 575 EXPORT_SYMBOL(noop_qdisc);
 576
 577 static int noqueue_init(struct Qdisc *qdisc, struct nlattr *opt,
 578                         struct netlink_ext_ack *extack)
 579 {
 580         /* register_qdisc() assigns a default of noop_enqueue if unset,
 581          * but __dev_queue_xmit() treats noqueue only as such
 582          * if this is NULL - so clear it here. */
 583         qdisc->enqueue = NULL;
 584         return 0;
 585 }
 586
 587 struct Qdisc_ops noqueue_qdisc_ops __read_mostly = {
 588         .id             =       "noqueue",
 589         .priv_size      =       0,
 590         .init           =       noqueue_init,
 591         .enqueue        =       noop_enqueue,
 592         .dequeue        =       noop_dequeue,
 593         .peek           =       noop_dequeue,
 594         .owner          =       THIS_MODULE,
 595 };
 596
 597 static const u8 prio2band[TC_PRIO_MAX + 1] = {
 598         1, 2, 2, 2, 1, 2, 0, 0 , 1, 1, 1, 1, 1, 1, 1, 1
 599 };
 600
 601 /* 3-band FIFO queue: old style, but should be a bit faster than
 602    generic prio+fifo combination.
 603  */
 604
 605 #define PFIFO_FAST_BANDS 3
 606
 607 /*
 608  * Private data for a pfifo_fast scheduler containing:
 609  *      - rings for priority bands
 610  */
 611 struct pfifo_fast_priv {
 612         struct skb_array q[PFIFO_FAST_BANDS];
 613 };
 614
 615 static inline struct skb_array *band2list(struct pfifo_fast_priv *priv,
 616                                           int band)
 617 {
 618         return &priv->q[band];
 619 }
 620
 621 static int pfifo_fast_enqueue(struct sk_buff *skb, struct Qdisc *qdisc,
 622                               struct sk_buff **to_free)
 623 {
 624         int band = prio2band[skb->priority & TC_PRIO_MAX];
 625         struct pfifo_fast_priv *priv = qdisc_priv(qdisc);
 626         struct skb_array *q = band2list(priv, band);
 627         unsigned int pkt_len = qdisc_pkt_len(skb);
 628         int err;
 629
 630         err = skb_array_produce(q, skb);
 631
 632         if (unlikely(err)) {
 633                 if (qdisc_is_percpu_stats(qdisc))
 634                         return qdisc_drop_cpu(skb, qdisc, to_free);
 635                 else
 636                         return qdisc_drop(skb, qdisc, to_free);
 637         }
 638
 639         qdisc_update_stats_at_enqueue(qdisc, pkt_len);
 640         return NET_XMIT_SUCCESS;
 641 }
 642
 643 static struct sk_buff *pfifo_fast_dequeue(struct Qdisc *qdisc)
 644 {
 645         struct pfifo_fast_priv *priv = qdisc_priv(qdisc);
 646         struct sk_buff *skb = NULL;
 647         int band;
 648
 649         for (band = 0; band < PFIFO_FAST_BANDS && !skb; band++) {
 650                 struct skb_array *q = band2list(priv, band);
 651
 652                 if (__skb_array_empty(q))
 653                         continue;
 654
 655                 skb = __skb_array_consume(q);
 656         }
 657         if (likely(skb)) {
 658                 qdisc_update_stats_at_dequeue(qdisc, skb);
 659         } else {
 660                 qdisc->empty = true;
 661         }
 662
 663         return skb;
 664 }
 665
 666 static struct sk_buff *pfifo_fast_peek(struct Qdisc *qdisc)
 667 {
 668         struct pfifo_fast_priv *priv = qdisc_priv(qdisc);
 669         struct sk_buff *skb = NULL;
 670         int band;
 671
 672         for (band = 0; band < PFIFO_FAST_BANDS && !skb; band++) {
 673                 struct skb_array *q = band2list(priv, band);
 674
 675                 skb = __skb_array_peek(q);
 676         }
 677
 678         return skb;
 679 }
 680
 681 static void pfifo_fast_reset(struct Qdisc *qdisc)
 682 {
 683         int i, band;
 684         struct pfifo_fast_priv *priv = qdisc_priv(qdisc);
 685
 686         for (band = 0; band < PFIFO_FAST_BANDS; band++) {
 687                 struct skb_array *q = band2list(priv, band);
 688                 struct sk_buff *skb;
 689
 690                 /* NULL ring is possible if destroy path is due to a failed
 691                  * skb_array_init() in pfifo_fast_init() case.
 692                  */
 693                 if (!q->ring.queue)
 694                         continue;
 695
 696                 while ((skb = __skb_array_consume(q)) != NULL)
 697                         kfree_skb(skb);
 698         }
 699
 700         if (qdisc_is_percpu_stats(qdisc)) {
 701                 for_each_possible_cpu(i) {
 702                         struct gnet_stats_queue *q;
 703
 704                         q = per_cpu_ptr(qdisc->cpu_qstats, i);
 705                         q->backlog = 0;
 706                         q->qlen = 0;
 707                 }
 708         }
 709 }
 710
 711 static int pfifo_fast_dump(struct Qdisc *qdisc, struct sk_buff *skb)
 712 {
 713         struct tc_prio_qopt opt = { .bands = PFIFO_FAST_BANDS };
 714
 715         memcpy(&opt.priomap, prio2band, TC_PRIO_MAX + 1);
 716         if (nla_put(skb, TCA_OPTIONS, sizeof(opt), &opt))
 717                 goto nla_put_failure;
 718         return skb->len;
 719
 720 nla_put_failure:
 721         return -1;
 722 }
 723
 724 static int pfifo_fast_init(struct Qdisc *qdisc, struct nlattr *opt,
 725                            struct netlink_ext_ack *extack)
 726 {
 727         unsigned int qlen = qdisc_dev(qdisc)->tx_queue_len;
 728         struct pfifo_fast_priv *priv = qdisc_priv(qdisc);
 729         int prio;
 730
 731         /* guard against zero length rings */
 732         if (!qlen)
 733                 return -EINVAL;
 734
 735         for (prio = 0; prio < PFIFO_FAST_BANDS; prio++) {
 736                 struct skb_array *q = band2list(priv, prio);
 737                 int err;
 738
 739                 err = skb_array_init(q, qlen, GFP_KERNEL);
 740                 if (err)
 741                         return -ENOMEM;
 742         }
 743
 744         /* Can by-pass the queue discipline */
 745         qdisc->flags |= TCQ_F_CAN_BYPASS;
 746         return 0;
 747 }
 748
 749 static void pfifo_fast_destroy(struct Qdisc *sch)
 750 {
 751         struct pfifo_fast_priv *priv = qdisc_priv(sch);
 752         int prio;
 753
 754         for (prio = 0; prio < PFIFO_FAST_BANDS; prio++) {
 755                 struct skb_array *q = band2list(priv, prio);
 756
 757                 /* NULL ring is possible if destroy path is due to a failed
 758                  * skb_array_init() in pfifo_fast_init() case.
 759                  */
 760                 if (!q->ring.queue)
 761                         continue;
 762                 /* Destroy ring but no need to kfree_skb because a call to
 763                  * pfifo_fast_reset() has already done that work.
 764                  */
 765                 ptr_ring_cleanup(&q->ring, NULL);
 766         }
 767 }
 768
 769 static int pfifo_fast_change_tx_queue_len(struct Qdisc *sch,
 770                                           unsigned int new_len)
 771 {
 772         struct pfifo_fast_priv *priv = qdisc_priv(sch);
 773         struct skb_array *bands[PFIFO_FAST_BANDS];
 774         int prio;
 775
 776         for (prio = 0; prio < PFIFO_FAST_BANDS; prio++) {
 777                 struct skb_array *q = band2list(priv, prio);
 778
 779                 bands[prio] = q;
 780         }
 781
 782         return skb_array_resize_multiple(bands, PFIFO_FAST_BANDS, new_len,
 783                                          GFP_KERNEL);
 784 }
 785
 786 struct Qdisc_ops pfifo_fast_ops __read_mostly = {
 787         .id             =       "pfifo_fast",
 788         .priv_size      =       sizeof(struct pfifo_fast_priv),
 789         .enqueue        =       pfifo_fast_enqueue,
 790         .dequeue        =       pfifo_fast_dequeue,
 791         .peek           =       pfifo_fast_peek,
 792         .init           =       pfifo_fast_init,
 793         .destroy        =       pfifo_fast_destroy,
 794         .reset          =       pfifo_fast_reset,
 795         .dump           =       pfifo_fast_dump,
 796         .change_tx_queue_len =  pfifo_fast_change_tx_queue_len,
 797         .owner          =       THIS_MODULE,
 798         .static_flags   =       TCQ_F_NOLOCK | TCQ_F_CPUSTATS,
 799 };
 800 EXPORT_SYMBOL(pfifo_fast_ops);
 801
 802 static struct lock_class_key qdisc_tx_busylock;
 803 static struct lock_class_key qdisc_running_key;
 804
 805 struct Qdisc *qdisc_alloc(struct netdev_queue *dev_queue,
 806                           const struct Qdisc_ops *ops,
 807                           struct netlink_ext_ack *extack)
 808 {
 809         void *p;
 810         struct Qdisc *sch;
 811         unsigned int size = QDISC_ALIGN(sizeof(*sch)) + ops->priv_size;
 812         int err = -ENOBUFS;
 813         struct net_device *dev;
 814
 815         if (!dev_queue) {
 816                 NL_SET_ERR_MSG(extack, "No device queue given");
 817                 err = -EINVAL;
 818                 goto errout;
 819         }
 820
 821         dev = dev_queue->dev;
 822         p = kzalloc_node(size, GFP_KERNEL,
 823                          netdev_queue_numa_node_read(dev_queue));
 824
 825         if (!p)
 826                 goto errout;
 827         sch = (struct Qdisc *) QDISC_ALIGN((unsigned long) p);
 828         /* if we got non aligned memory, ask more and do alignment ourself */
 829         if (sch != p) {
 830                 kfree(p);
 831                 p = kzalloc_node(size + QDISC_ALIGNTO - 1, GFP_KERNEL,
 832                                  netdev_queue_numa_node_read(dev_queue));
 833                 if (!p)
 834                         goto errout;
 835                 sch = (struct Qdisc *) QDISC_ALIGN((unsigned long) p);
 836                 sch->padded = (char *) sch - (char *) p;
 837         }
 838         __skb_queue_head_init(&sch->gso_skb);
 839         __skb_queue_head_init(&sch->skb_bad_txq);
 840         qdisc_skb_head_init(&sch->q);
 841         spin_lock_init(&sch->q.lock);
 842
 843         if (ops->static_flags & TCQ_F_CPUSTATS) {
 844                 sch->cpu_bstats =
 845                         netdev_alloc_pcpu_stats(struct gnet_stats_basic_cpu);
 846                 if (!sch->cpu_bstats)
 847                         goto errout1;
 848
 849                 sch->cpu_qstats = alloc_percpu(struct gnet_stats_queue);
 850                 if (!sch->cpu_qstats) {
 851                         free_percpu(sch->cpu_bstats);
 852                         goto errout1;
 853                 }
 854         }
 855
 856         spin_lock_init(&sch->busylock);
 857         lockdep_set_class(&sch->busylock,
 858                           dev->qdisc_tx_busylock ?: &qdisc_tx_busylock);
 859
 860         /* seqlock has the same scope of busylock, for NOLOCK qdisc */
 861         spin_lock_init(&sch->seqlock);
 862         lockdep_set_class(&sch->busylock,
 863                           dev->qdisc_tx_busylock ?: &qdisc_tx_busylock);
 864
 865         seqcount_init(&sch->running);
 866         lockdep_set_class(&sch->running,
 867                           dev->qdisc_running_key ?: &qdisc_running_key);
 868
 869         sch->ops = ops;
 870         sch->flags = ops->static_flags;
 871         sch->enqueue = ops->enqueue;
 872         sch->dequeue = ops->dequeue;
 873         sch->dev_queue = dev_queue;
 874         sch->empty = true;
 875         dev_hold(dev);
 876         refcount_set(&sch->refcnt, 1);
 877
 878         return sch;
 879 errout1:
 880         kfree(p);
 881 errout:
 882         return ERR_PTR(err);
 883 }
 884
 885 struct Qdisc *qdisc_create_dflt(struct netdev_queue *dev_queue,
 886                                 const struct Qdisc_ops *ops,
 887                                 unsigned int parentid,
 888                                 struct netlink_ext_ack *extack)
 889 {
 890         struct Qdisc *sch;
 891
 892         if (!try_module_get(ops->owner)) {
 893                 NL_SET_ERR_MSG(extack, "Failed to increase module reference counter");
 894                 return NULL;
 895         }
 896
 897         sch = qdisc_alloc(dev_queue, ops, extack);
 898         if (IS_ERR(sch)) {
 899                 module_put(ops->owner);
 900                 return NULL;
 901         }
 902         sch->parent = parentid;
 903
 904         if (!ops->init || ops->init(sch, NULL, extack) == 0)
 905                 return sch;
 906
 907         qdisc_put(sch);
 908         return NULL;
 909 }
 910 EXPORT_SYMBOL(qdisc_create_dflt);
 911
 912 /* Under qdisc_lock(qdisc) and BH! */
 913
 914 void qdisc_reset(struct Qdisc *qdisc)
 915 {
 916         const struct Qdisc_ops *ops = qdisc->ops;
 917         struct sk_buff *skb, *tmp;
 918
 919         if (ops->reset)
 920                 ops->reset(qdisc);
 921
 922         skb_queue_walk_safe(&qdisc->gso_skb, skb, tmp) {
 923                 __skb_unlink(skb, &qdisc->gso_skb);
 924                 kfree_skb_list(skb);
 925         }
 926
 927         skb_queue_walk_safe(&qdisc->skb_bad_txq, skb, tmp) {
 928                 __skb_unlink(skb, &qdisc->skb_bad_txq);
 929                 kfree_skb_list(skb);
 930         }
 931
 932         qdisc->q.qlen = 0;
 933         qdisc->qstats.backlog = 0;
 934 }
 935 EXPORT_SYMBOL(qdisc_reset);
 936
 937 void qdisc_free(struct Qdisc *qdisc)
 938 {
 939         if (qdisc_is_percpu_stats(qdisc)) {
 940                 free_percpu(qdisc->cpu_bstats);
 941                 free_percpu(qdisc->cpu_qstats);
 942         }
 943
 944         kfree((char *) qdisc - qdisc->padded);
 945 }
 946
 947 static void qdisc_free_cb(struct rcu_head *head)
 948 {
 949         struct Qdisc *q = container_of(head, struct Qdisc, rcu);
 950
 951         qdisc_free(q);
 952 }
 953
 954 static void qdisc_destroy(struct Qdisc *qdisc)
 955 {
 956         const struct Qdisc_ops  *ops = qdisc->ops;
 957         struct sk_buff *skb, *tmp;
 958
 959 #ifdef CONFIG_NET_SCHED
 960         qdisc_hash_del(qdisc);
 961
 962         qdisc_put_stab(rtnl_dereference(qdisc->stab));
 963 #endif
 964         gen_kill_estimator(&qdisc->rate_est);
 965         if (ops->reset)
 966                 ops->reset(qdisc);
 967         if (ops->destroy)
 968                 ops->destroy(qdisc);
 969
 970         module_put(ops->owner);
 971         dev_put(qdisc_dev(qdisc));
 972
 973         skb_queue_walk_safe(&qdisc->gso_skb, skb, tmp) {
 974                 __skb_unlink(skb, &qdisc->gso_skb);
 975                 kfree_skb_list(skb);
 976         }
 977
 978         skb_queue_walk_safe(&qdisc->skb_bad_txq, skb, tmp) {
 979                 __skb_unlink(skb, &qdisc->skb_bad_txq);
 980                 kfree_skb_list(skb);
 981         }
 982
 983         call_rcu(&qdisc->rcu, qdisc_free_cb);
 984 }
 985
 986 void qdisc_put(struct Qdisc *qdisc)
 987 {
 988         if (qdisc->flags & TCQ_F_BUILTIN ||
 989             !refcount_dec_and_test(&qdisc->refcnt))
 990                 return;
 991
 992         qdisc_destroy(qdisc);
 993 }
 994 EXPORT_SYMBOL(qdisc_put);
 995
 996 /* Version of qdisc_put() that is called with rtnl mutex unlocked.
 997  * Intended to be used as optimization, this function only takes rtnl lock if
 998  * qdisc reference counter reached zero.
 999  */
1000
1001 void qdisc_put_unlocked(struct Qdisc *qdisc)
1002 {
1003         if (qdisc->flags & TCQ_F_BUILTIN ||
1004             !refcount_dec_and_rtnl_lock(&qdisc->refcnt))
1005                 return;
1006
1007         qdisc_destroy(qdisc);
1008         rtnl_unlock();
1009 }
1010 EXPORT_SYMBOL(qdisc_put_unlocked);
1011
1012 /* Attach toplevel qdisc to device queue. */
1013 struct Qdisc *dev_graft_qdisc(struct netdev_queue *dev_queue,
1014                               struct Qdisc *qdisc)
1015 {
1016         struct Qdisc *oqdisc = dev_queue->qdisc_sleeping;
1017         spinlock_t *root_lock;
1018
1019         root_lock = qdisc_lock(oqdisc);
1020         spin_lock_bh(root_lock);
1021
1022         /* ... and graft new one */
1023         if (qdisc == NULL)
1024                 qdisc = &noop_qdisc;
1025         dev_queue->qdisc_sleeping = qdisc;
1026         rcu_assign_pointer(dev_queue->qdisc, &noop_qdisc);
1027
1028         spin_unlock_bh(root_lock);
1029
1030         return oqdisc;
1031 }
1032 EXPORT_SYMBOL(dev_graft_qdisc);
1033
1034 static void attach_one_default_qdisc(struct net_device *dev,
1035                                      struct netdev_queue *dev_queue,
1036                                      void *_unused)
1037 {
1038         struct Qdisc *qdisc;
1039         const struct Qdisc_ops *ops = default_qdisc_ops;
1040
1041         if (dev->priv_flags & IFF_NO_QUEUE)
1042                 ops = &noqueue_qdisc_ops;
1043
1044         qdisc = qdisc_create_dflt(dev_queue, ops, TC_H_ROOT, NULL);
1045         if (!qdisc) {
1046                 netdev_info(dev, "activation failed\n");
1047                 return;
1048         }
1049         if (!netif_is_multiqueue(dev))
1050                 qdisc->flags |= TCQ_F_ONETXQUEUE | TCQ_F_NOPARENT;
1051         dev_queue->qdisc_sleeping = qdisc;
1052 }
1053
1054 static void attach_default_qdiscs(struct net_device *dev)
1055 {
1056         struct netdev_queue *txq;
1057         struct Qdisc *qdisc;
1058
1059         txq = netdev_get_tx_queue(dev, 0);
1060
1061         if (!netif_is_multiqueue(dev) ||
1062             dev->priv_flags & IFF_NO_QUEUE) {
1063                 netdev_for_each_tx_queue(dev, attach_one_default_qdisc, NULL);
1064                 dev->qdisc = txq->qdisc_sleeping;
1065                 qdisc_refcount_inc(dev->qdisc);
1066         } else {
1067                 qdisc = qdisc_create_dflt(txq, &mq_qdisc_ops, TC_H_ROOT, NULL);
1068                 if (qdisc) {
1069                         dev->qdisc = qdisc;
1070                         qdisc->ops->attach(qdisc);
1071                 }
1072         }
1073 #ifdef CONFIG_NET_SCHED
1074         if (dev->qdisc != &noop_qdisc)
1075                 qdisc_hash_add(dev->qdisc, false);
1076 #endif
1077 }
1078
1079 static void transition_one_qdisc(struct net_device *dev,
1080                                  struct netdev_queue *dev_queue,
1081                                  void *_need_watchdog)
1082 {
1083         struct Qdisc *new_qdisc = dev_queue->qdisc_sleeping;
1084         int *need_watchdog_p = _need_watchdog;
1085
1086         if (!(new_qdisc->flags & TCQ_F_BUILTIN))
1087                 clear_bit(__QDISC_STATE_DEACTIVATED, &new_qdisc->state);
1088
1089         rcu_assign_pointer(dev_queue->qdisc, new_qdisc);
1090         if (need_watchdog_p) {
1091                 dev_queue->trans_start = 0;
1092                 *need_watchdog_p = 1;
1093         }
1094 }
1095
1096 void dev_activate(struct net_device *dev)
1097 {
1098         int need_watchdog;
1099
1100         /* No queueing discipline is attached to device;
1101          * create default one for devices, which need queueing
1102          * and noqueue_qdisc for virtual interfaces
1103          */
1104
1105         if (dev->qdisc == &noop_qdisc)
1106                 attach_default_qdiscs(dev);
1107
1108         if (!netif_carrier_ok(dev))
1109                 /* Delay activation until next carrier-on event */
1110                 return;
1111
1112         need_watchdog = 0;
1113         netdev_for_each_tx_queue(dev, transition_one_qdisc, &need_watchdog);
1114         if (dev_ingress_queue(dev))
1115                 transition_one_qdisc(dev, dev_ingress_queue(dev), NULL);
1116
1117         if (need_watchdog) {
1118                 netif_trans_update(dev);
1119                 dev_watchdog_up(dev);
1120         }
1121 }
1122 EXPORT_SYMBOL(dev_activate);
1123
1124 static void dev_deactivate_queue(struct net_device *dev,
1125                                  struct netdev_queue *dev_queue,
1126                                  void *_qdisc_default)
1127 {
1128         struct Qdisc *qdisc_default = _qdisc_default;
1129         struct Qdisc *qdisc;
1130
1131         qdisc = rtnl_dereference(dev_queue->qdisc);
1132         if (qdisc) {
1133                 bool nolock = qdisc->flags & TCQ_F_NOLOCK;
1134
1135                 if (nolock)
1136                         spin_lock_bh(&qdisc->seqlock);
1137                 spin_lock_bh(qdisc_lock(qdisc));
1138
1139                 if (!(qdisc->flags & TCQ_F_BUILTIN))
1140                         set_bit(__QDISC_STATE_DEACTIVATED, &qdisc->state);
1141
1142                 rcu_assign_pointer(dev_queue->qdisc, qdisc_default);
1143                 qdisc_reset(qdisc);
1144
1145                 spin_unlock_bh(qdisc_lock(qdisc));
1146                 if (nolock)
1147                         spin_unlock_bh(&qdisc->seqlock);
1148         }
1149 }
1150
1151 static bool some_qdisc_is_busy(struct net_device *dev)
1152 {
1153         unsigned int i;
1154
1155         for (i = 0; i < dev->num_tx_queues; i++) {
1156                 struct netdev_queue *dev_queue;
1157                 spinlock_t *root_lock;
1158                 struct Qdisc *q;
1159                 int val;
1160
1161                 dev_queue = netdev_get_tx_queue(dev, i);
1162                 q = dev_queue->qdisc_sleeping;
1163
1164                 root_lock = qdisc_lock(q);
1165                 spin_lock_bh(root_lock);
1166
1167                 val = (qdisc_is_running(q) ||
1168                        test_bit(__QDISC_STATE_SCHED, &q->state));
1169
1170                 spin_unlock_bh(root_lock);
1171
1172                 if (val)
1173                         return true;
1174         }
1175         return false;
1176 }
1177
1178 static void dev_qdisc_reset(struct net_device *dev,
1179                             struct netdev_queue *dev_queue,
1180                             void *none)
1181 {
1182         struct Qdisc *qdisc = dev_queue->qdisc_sleeping;
1183
1184         if (qdisc)
1185                 qdisc_reset(qdisc);
1186 }
1187
1188 /**
1189  *      dev_deactivate_many - deactivate transmissions on several devices
1190  *      @head: list of devices to deactivate
1191  *
1192  *      This function returns only when all outstanding transmissions
1193  *      have completed, unless all devices are in dismantle phase.
1194  */
1195 void dev_deactivate_many(struct list_head *head)
1196 {
1197         struct net_device *dev;
1198
1199         list_for_each_entry(dev, head, close_list) {
1200                 netdev_for_each_tx_queue(dev, dev_deactivate_queue,
1201                                          &noop_qdisc);
1202                 if (dev_ingress_queue(dev))
1203                         dev_deactivate_queue(dev, dev_ingress_queue(dev),
1204                                              &noop_qdisc);
1205
1206                 dev_watchdog_down(dev);
1207         }
1208
1209         /* Wait for outstanding qdisc-less dev_queue_xmit calls.
1210          * This is avoided if all devices are in dismantle phase :
1211          * Caller will call synchronize_net() for us
1212          */
1213         synchronize_net();
1214
1215         /* Wait for outstanding qdisc_run calls. */
1216         list_for_each_entry(dev, head, close_list) {
1217                 while (some_qdisc_is_busy(dev))
1218                         yield();
1219                 /* The new qdisc is assigned at this point so we can safely
1220                  * unwind stale skb lists and qdisc statistics
1221                  */
1222                 netdev_for_each_tx_queue(dev, dev_qdisc_reset, NULL);
1223                 if (dev_ingress_queue(dev))
1224                         dev_qdisc_reset(dev, dev_ingress_queue(dev), NULL);
1225         }
1226 }
1227
1228 void dev_deactivate(struct net_device *dev)
1229 {
1230         LIST_HEAD(single);
1231
1232         list_add(&dev->close_list, &single);
1233         dev_deactivate_many(&single);
1234         list_del(&single);
1235 }
1236 EXPORT_SYMBOL(dev_deactivate);
1237
1238 static int qdisc_change_tx_queue_len(struct net_device *dev,
1239                                      struct netdev_queue *dev_queue)
1240 {
1241         struct Qdisc *qdisc = dev_queue->qdisc_sleeping;
1242         const struct Qdisc_ops *ops = qdisc->ops;
1243
1244         if (ops->change_tx_queue_len)
1245                 return ops->change_tx_queue_len(qdisc, dev->tx_queue_len);
1246         return 0;
1247 }
1248
1249 int dev_qdisc_change_tx_queue_len(struct net_device *dev)
1250 {
1251         bool up = dev->flags & IFF_UP;
1252         unsigned int i;
1253         int ret = 0;
1254
1255         if (up)
1256                 dev_deactivate(dev);
1257
1258         for (i = 0; i < dev->num_tx_queues; i++) {
1259                 ret = qdisc_change_tx_queue_len(dev, &dev->_tx[i]);
1260
1261                 /* TODO: revert changes on a partial failure */
1262                 if (ret)
1263                         break;
1264         }
1265
1266         if (up)
1267                 dev_activate(dev);
1268         return ret;
1269 }
1270
1271 static void dev_init_scheduler_queue(struct net_device *dev,
1272                                      struct netdev_queue *dev_queue,
1273                                      void *_qdisc)
1274 {
1275         struct Qdisc *qdisc = _qdisc;
1276
1277         rcu_assign_pointer(dev_queue->qdisc, qdisc);
1278         dev_queue->qdisc_sleeping = qdisc;
1279 }
1280
1281 void dev_init_scheduler(struct net_device *dev)
1282 {
1283         dev->qdisc = &noop_qdisc;
1284         netdev_for_each_tx_queue(dev, dev_init_scheduler_queue, &noop_qdisc);
1285         if (dev_ingress_queue(dev))
1286                 dev_init_scheduler_queue(dev, dev_ingress_queue(dev), &noop_qdisc);
1287
1288         timer_setup(&dev->watchdog_timer, dev_watchdog, 0);
1289 }
1290
1291 static void shutdown_scheduler_queue(struct net_device *dev,
1292                                      struct netdev_queue *dev_queue,
1293                                      void *_qdisc_default)
1294 {
1295         struct Qdisc *qdisc = dev_queue->qdisc_sleeping;
1296         struct Qdisc *qdisc_default = _qdisc_default;
1297
1298         if (qdisc) {
1299                 rcu_assign_pointer(dev_queue->qdisc, qdisc_default);
1300                 dev_queue->qdisc_sleeping = qdisc_default;
1301
1302                 qdisc_put(qdisc);
1303         }
1304 }
1305
1306 void dev_shutdown(struct net_device *dev)
1307 {
1308         netdev_for_each_tx_queue(dev, shutdown_scheduler_queue, &noop_qdisc);
1309         if (dev_ingress_queue(dev))
1310                 shutdown_scheduler_queue(dev, dev_ingress_queue(dev), &noop_qdisc);
1311         qdisc_put(dev->qdisc);
1312         dev->qdisc = &noop_qdisc;
1313
1314         WARN_ON(timer_pending(&dev->watchdog_timer));
1315 }
1316
1317 void psched_ratecfg_precompute(struct psched_ratecfg *r,
1318                                const struct tc_ratespec *conf,
1319                                u64 rate64)
1320 {
1321         memset(r, 0, sizeof(*r));
1322         r->overhead = conf->overhead;
1323         r->rate_bytes_ps = max_t(u64, conf->rate, rate64);
1324         r->linklayer = (conf->linklayer & TC_LINKLAYER_MASK);
1325         r->mult = 1;
1326         /*
1327          * The deal here is to replace a divide by a reciprocal one
1328          * in fast path (a reciprocal divide is a multiply and a shift)
1329          *
1330          * Normal formula would be :
1331          *  time_in_ns = (NSEC_PER_SEC * len) / rate_bps
1332          *
1333          * We compute mult/shift to use instead :
1334          *  time_in_ns = (len * mult) >> shift;
1335          *
1336          * We try to get the highest possible mult value for accuracy,
1337          * but have to make sure no overflows will ever happen.
1338          */
1339         if (r->rate_bytes_ps > 0) {
1340                 u64 factor = NSEC_PER_SEC;
1341
1342                 for (;;) {
1343                         r->mult = div64_u64(factor, r->rate_bytes_ps);
1344                         if (r->mult & (1U << 31) || factor & (1ULL << 63))
1345                                 break;
1346                         factor <<= 1;
1347                         r->shift++;
1348                 }
1349         }
1350 }
1351 EXPORT_SYMBOL(psched_ratecfg_precompute);
1352
1353 static void mini_qdisc_rcu_func(struct rcu_head *head)
1354 {
1355 }
1356
1357 void mini_qdisc_pair_swap(struct mini_Qdisc_pair *miniqp,
1358                           struct tcf_proto *tp_head)
1359 {
1360         /* Protected with chain0->filter_chain_lock.
1361          * Can't access chain directly because tp_head can be NULL.
1362          */
1363         struct mini_Qdisc *miniq_old =
1364                 rcu_dereference_protected(*miniqp->p_miniq, 1);
1365         struct mini_Qdisc *miniq;
1366
1367         if (!tp_head) {
1368                 RCU_INIT_POINTER(*miniqp->p_miniq, NULL);
1369                 /* Wait for flying RCU callback before it is freed. */
1370                 rcu_barrier();
1371                 return;
1372         }
1373
1374         miniq = !miniq_old || miniq_old == &miniqp->miniq2 ?
1375                 &miniqp->miniq1 : &miniqp->miniq2;
1376
1377         /* We need to make sure that readers won't see the miniq
1378          * we are about to modify. So wait until previous call_rcu callback
1379          * is done.
1380          */
1381         rcu_barrier();
1382         miniq->filter_list = tp_head;
1383         rcu_assign_pointer(*miniqp->p_miniq, miniq);
1384
1385         if (miniq_old)
1386                 /* This is counterpart of the rcu barriers above. We need to
1387                  * block potential new user of miniq_old until all readers
1388                  * are not seeing it.
1389                  */
1390                 call_rcu(&miniq_old->rcu, mini_qdisc_rcu_func);
1391 }
1392 EXPORT_SYMBOL(mini_qdisc_pair_swap);
1393
1394 void mini_qdisc_pair_init(struct mini_Qdisc_pair *miniqp, struct Qdisc *qdisc,
1395                           struct mini_Qdisc __rcu **p_miniq)
1396 {
1397         miniqp->miniq1.cpu_bstats = qdisc->cpu_bstats;
1398         miniqp->miniq1.cpu_qstats = qdisc->cpu_qstats;
1399         miniqp->miniq2.cpu_bstats = qdisc->cpu_bstats;
1400         miniqp->miniq2.cpu_qstats = qdisc->cpu_qstats;
1401         miniqp->p_miniq = p_miniq;
1402 }
1403 EXPORT_SYMBOL(mini_qdisc_pair_init);