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                 quota -= packets;
 386                 if (quota <= 0) {
 387                         __netif_schedule(q);
 388                         break;
 389                 }
 390         }
 391 }
 392
 393 unsigned long dev_trans_start(struct net_device *dev)
 394 {
 395         unsigned long val, res;
 396         unsigned int i;
 397
 398         if (is_vlan_dev(dev))
 399                 dev = vlan_dev_real_dev(dev);
 400         else if (netif_is_macvlan(dev))
 401                 dev = macvlan_dev_real_dev(dev);
 402         res = netdev_get_tx_queue(dev, 0)->trans_start;
 403         for (i = 1; i < dev->num_tx_queues; i++) {
 404                 val = netdev_get_tx_queue(dev, i)->trans_start;
 405                 if (val && time_after(val, res))
 406                         res = val;
 407         }
 408
 409         return res;
 410 }
 411 EXPORT_SYMBOL(dev_trans_start);
 412
 413 static void dev_watchdog(struct timer_list *t)
 414 {
 415         struct net_device *dev = from_timer(dev, t, watchdog_timer);
 416
 417         netif_tx_lock(dev);
 418         if (!qdisc_tx_is_noop(dev)) {
 419                 if (netif_device_present(dev) &&
 420                     netif_running(dev) &&
 421                     netif_carrier_ok(dev)) {
 422                         int some_queue_timedout = 0;
 423                         unsigned int i;
 424                         unsigned long trans_start;
 425
 426                         for (i = 0; i < dev->num_tx_queues; i++) {
 427                                 struct netdev_queue *txq;
 428
 429                                 txq = netdev_get_tx_queue(dev, i);
 430                                 trans_start = txq->trans_start;
 431                                 if (netif_xmit_stopped(txq) &&
 432                                     time_after(jiffies, (trans_start +
 433                                                          dev->watchdog_timeo))) {
 434                                         some_queue_timedout = 1;
 435                                         txq->trans_timeout++;
 436                                         break;
 437                                 }
 438                         }
 439
 440                         if (some_queue_timedout) {
 441                                 trace_net_dev_xmit_timeout(dev, i);
 442                                 WARN_ONCE(1, KERN_INFO "NETDEV WATCHDOG: %s (%s): transmit queue %u timed out\n",
 443                                        dev->name, netdev_drivername(dev), i);
 444                                 dev->netdev_ops->ndo_tx_timeout(dev, i);
 445                         }
 446                         if (!mod_timer(&dev->watchdog_timer,
 447                                        round_jiffies(jiffies +
 448                                                      dev->watchdog_timeo)))
 449                                 dev_hold(dev);
 450                 }
 451         }
 452         netif_tx_unlock(dev);
 453
 454         dev_put(dev);
 455 }
 456
 457 void __netdev_watchdog_up(struct net_device *dev)
 458 {
 459         if (dev->netdev_ops->ndo_tx_timeout) {
 460                 if (dev->watchdog_timeo <= 0)
 461                         dev->watchdog_timeo = 5*HZ;
 462                 if (!mod_timer(&dev->watchdog_timer,
 463                                round_jiffies(jiffies + dev->watchdog_timeo)))
 464                         dev_hold(dev);
 465         }
 466 }
 467 EXPORT_SYMBOL_GPL(__netdev_watchdog_up);
 468
 469 static void dev_watchdog_up(struct net_device *dev)
 470 {
 471         __netdev_watchdog_up(dev);
 472 }
 473
 474 static void dev_watchdog_down(struct net_device *dev)
 475 {
 476         netif_tx_lock_bh(dev);
 477         if (del_timer(&dev->watchdog_timer))
 478                 dev_put(dev);
 479         netif_tx_unlock_bh(dev);
 480 }
 481
 482 /**
 483  *      netif_carrier_on - set carrier
 484  *      @dev: network device
 485  *
 486  * Device has detected acquisition of carrier.
 487  */
 488 void netif_carrier_on(struct net_device *dev)
 489 {
 490         if (test_and_clear_bit(__LINK_STATE_NOCARRIER, &dev->state)) {
 491                 if (dev->reg_state == NETREG_UNINITIALIZED)
 492                         return;
 493                 atomic_inc(&dev->carrier_up_count);
 494                 linkwatch_fire_event(dev);
 495                 if (netif_running(dev))
 496                         __netdev_watchdog_up(dev);
 497         }
 498 }
 499 EXPORT_SYMBOL(netif_carrier_on);
 500
 501 /**
 502  *      netif_carrier_off - clear carrier
 503  *      @dev: network device
 504  *
 505  * Device has detected loss of carrier.
 506  */
 507 void netif_carrier_off(struct net_device *dev)
 508 {
 509         if (!test_and_set_bit(__LINK_STATE_NOCARRIER, &dev->state)) {
 510                 if (dev->reg_state == NETREG_UNINITIALIZED)
 511                         return;
 512                 atomic_inc(&dev->carrier_down_count);
 513                 linkwatch_fire_event(dev);
 514         }
 515 }
 516 EXPORT_SYMBOL(netif_carrier_off);
 517
 518 /* "NOOP" scheduler: the best scheduler, recommended for all interfaces
 519    under all circumstances. It is difficult to invent anything faster or
 520    cheaper.
 521  */
 522
 523 static int noop_enqueue(struct sk_buff *skb, struct Qdisc *qdisc,
 524                         struct sk_buff **to_free)
 525 {
 526         __qdisc_drop(skb, to_free);
 527         return NET_XMIT_CN;
 528 }
 529
 530 static struct sk_buff *noop_dequeue(struct Qdisc *qdisc)
 531 {
 532         return NULL;
 533 }
 534
 535 struct Qdisc_ops noop_qdisc_ops __read_mostly = {
 536         .id             =       "noop",
 537         .priv_size      =       0,
 538         .enqueue        =       noop_enqueue,
 539         .dequeue        =       noop_dequeue,
 540         .peek           =       noop_dequeue,
 541         .owner          =       THIS_MODULE,
 542 };
 543
 544 static struct netdev_queue noop_netdev_queue = {
 545         RCU_POINTER_INITIALIZER(qdisc, &noop_qdisc),
 546         .qdisc_sleeping =       &noop_qdisc,
 547 };
 548
 549 struct Qdisc noop_qdisc = {
 550         .enqueue        =       noop_enqueue,
 551         .dequeue        =       noop_dequeue,
 552         .flags          =       TCQ_F_BUILTIN,
 553         .ops            =       &noop_qdisc_ops,
 554         .q.lock         =       __SPIN_LOCK_UNLOCKED(noop_qdisc.q.lock),
 555         .dev_queue      =       &noop_netdev_queue,
 556         .running        =       SEQCNT_ZERO(noop_qdisc.running),
 557         .busylock       =       __SPIN_LOCK_UNLOCKED(noop_qdisc.busylock),
 558         .gso_skb = {
 559                 .next = (struct sk_buff *)&noop_qdisc.gso_skb,
 560                 .prev = (struct sk_buff *)&noop_qdisc.gso_skb,
 561                 .qlen = 0,
 562                 .lock = __SPIN_LOCK_UNLOCKED(noop_qdisc.gso_skb.lock),
 563         },
 564         .skb_bad_txq = {
 565                 .next = (struct sk_buff *)&noop_qdisc.skb_bad_txq,
 566                 .prev = (struct sk_buff *)&noop_qdisc.skb_bad_txq,
 567                 .qlen = 0,
 568                 .lock = __SPIN_LOCK_UNLOCKED(noop_qdisc.skb_bad_txq.lock),
 569         },
 570 };
 571 EXPORT_SYMBOL(noop_qdisc);
 572
 573 static int noqueue_init(struct Qdisc *qdisc, struct nlattr *opt,
 574                         struct netlink_ext_ack *extack)
 575 {
 576         /* register_qdisc() assigns a default of noop_enqueue if unset,
 577          * but __dev_queue_xmit() treats noqueue only as such
 578          * if this is NULL - so clear it here. */
 579         qdisc->enqueue = NULL;
 580         return 0;
 581 }
 582
 583 struct Qdisc_ops noqueue_qdisc_ops __read_mostly = {
 584         .id             =       "noqueue",
 585         .priv_size      =       0,
 586         .init           =       noqueue_init,
 587         .enqueue        =       noop_enqueue,
 588         .dequeue        =       noop_dequeue,
 589         .peek           =       noop_dequeue,
 590         .owner          =       THIS_MODULE,
 591 };
 592
 593 static const u8 prio2band[TC_PRIO_MAX + 1] = {
 594         1, 2, 2, 2, 1, 2, 0, 0 , 1, 1, 1, 1, 1, 1, 1, 1
 595 };
 596
 597 /* 3-band FIFO queue: old style, but should be a bit faster than
 598    generic prio+fifo combination.
 599  */
 600
 601 #define PFIFO_FAST_BANDS 3
 602
 603 /*
 604  * Private data for a pfifo_fast scheduler containing:
 605  *      - rings for priority bands
 606  */
 607 struct pfifo_fast_priv {
 608         struct skb_array q[PFIFO_FAST_BANDS];
 609 };
 610
 611 static inline struct skb_array *band2list(struct pfifo_fast_priv *priv,
 612                                           int band)
 613 {
 614         return &priv->q[band];
 615 }
 616
 617 static int pfifo_fast_enqueue(struct sk_buff *skb, struct Qdisc *qdisc,
 618                               struct sk_buff **to_free)
 619 {
 620         int band = prio2band[skb->priority & TC_PRIO_MAX];
 621         struct pfifo_fast_priv *priv = qdisc_priv(qdisc);
 622         struct skb_array *q = band2list(priv, band);
 623         unsigned int pkt_len = qdisc_pkt_len(skb);
 624         int err;
 625
 626         err = skb_array_produce(q, skb);
 627
 628         if (unlikely(err)) {
 629                 if (qdisc_is_percpu_stats(qdisc))
 630                         return qdisc_drop_cpu(skb, qdisc, to_free);
 631                 else
 632                         return qdisc_drop(skb, qdisc, to_free);
 633         }
 634
 635         qdisc_update_stats_at_enqueue(qdisc, pkt_len);
 636         return NET_XMIT_SUCCESS;
 637 }
 638
 639 static struct sk_buff *pfifo_fast_dequeue(struct Qdisc *qdisc)
 640 {
 641         struct pfifo_fast_priv *priv = qdisc_priv(qdisc);
 642         struct sk_buff *skb = NULL;
 643         int band;
 644
 645         for (band = 0; band < PFIFO_FAST_BANDS && !skb; band++) {
 646                 struct skb_array *q = band2list(priv, band);
 647
 648                 if (__skb_array_empty(q))
 649                         continue;
 650
 651                 skb = __skb_array_consume(q);
 652         }
 653         if (likely(skb)) {
 654                 qdisc_update_stats_at_dequeue(qdisc, skb);
 655         } else {
 656                 WRITE_ONCE(qdisc->empty, true);
 657         }
 658
 659         return skb;
 660 }
 661
 662 static struct sk_buff *pfifo_fast_peek(struct Qdisc *qdisc)
 663 {
 664         struct pfifo_fast_priv *priv = qdisc_priv(qdisc);
 665         struct sk_buff *skb = NULL;
 666         int band;
 667
 668         for (band = 0; band < PFIFO_FAST_BANDS && !skb; band++) {
 669                 struct skb_array *q = band2list(priv, band);
 670
 671                 skb = __skb_array_peek(q);
 672         }
 673
 674         return skb;
 675 }
 676
 677 static void pfifo_fast_reset(struct Qdisc *qdisc)
 678 {
 679         int i, band;
 680         struct pfifo_fast_priv *priv = qdisc_priv(qdisc);
 681
 682         for (band = 0; band < PFIFO_FAST_BANDS; band++) {
 683                 struct skb_array *q = band2list(priv, band);
 684                 struct sk_buff *skb;
 685
 686                 /* NULL ring is possible if destroy path is due to a failed
 687                  * skb_array_init() in pfifo_fast_init() case.
 688                  */
 689                 if (!q->ring.queue)
 690                         continue;
 691
 692                 while ((skb = __skb_array_consume(q)) != NULL)
 693                         kfree_skb(skb);
 694         }
 695
 696         if (qdisc_is_percpu_stats(qdisc)) {
 697                 for_each_possible_cpu(i) {
 698                         struct gnet_stats_queue *q;
 699
 700                         q = per_cpu_ptr(qdisc->cpu_qstats, i);
 701                         q->backlog = 0;
 702                         q->qlen = 0;
 703                 }
 704         }
 705 }
 706
 707 static int pfifo_fast_dump(struct Qdisc *qdisc, struct sk_buff *skb)
 708 {
 709         struct tc_prio_qopt opt = { .bands = PFIFO_FAST_BANDS };
 710
 711         memcpy(&opt.priomap, prio2band, TC_PRIO_MAX + 1);
 712         if (nla_put(skb, TCA_OPTIONS, sizeof(opt), &opt))
 713                 goto nla_put_failure;
 714         return skb->len;
 715
 716 nla_put_failure:
 717         return -1;
 718 }
 719
 720 static int pfifo_fast_init(struct Qdisc *qdisc, struct nlattr *opt,
 721                            struct netlink_ext_ack *extack)
 722 {
 723         unsigned int qlen = qdisc_dev(qdisc)->tx_queue_len;
 724         struct pfifo_fast_priv *priv = qdisc_priv(qdisc);
 725         int prio;
 726
 727         /* guard against zero length rings */
 728         if (!qlen)
 729                 return -EINVAL;
 730
 731         for (prio = 0; prio < PFIFO_FAST_BANDS; prio++) {
 732                 struct skb_array *q = band2list(priv, prio);
 733                 int err;
 734
 735                 err = skb_array_init(q, qlen, GFP_KERNEL);
 736                 if (err)
 737                         return -ENOMEM;
 738         }
 739
 740         /* Can by-pass the queue discipline */
 741         qdisc->flags |= TCQ_F_CAN_BYPASS;
 742         return 0;
 743 }
 744
 745 static void pfifo_fast_destroy(struct Qdisc *sch)
 746 {
 747         struct pfifo_fast_priv *priv = qdisc_priv(sch);
 748         int prio;
 749
 750         for (prio = 0; prio < PFIFO_FAST_BANDS; prio++) {
 751                 struct skb_array *q = band2list(priv, prio);
 752
 753                 /* NULL ring is possible if destroy path is due to a failed
 754                  * skb_array_init() in pfifo_fast_init() case.
 755                  */
 756                 if (!q->ring.queue)
 757                         continue;
 758                 /* Destroy ring but no need to kfree_skb because a call to
 759                  * pfifo_fast_reset() has already done that work.
 760                  */
 761                 ptr_ring_cleanup(&q->ring, NULL);
 762         }
 763 }
 764
 765 static int pfifo_fast_change_tx_queue_len(struct Qdisc *sch,
 766                                           unsigned int new_len)
 767 {
 768         struct pfifo_fast_priv *priv = qdisc_priv(sch);
 769         struct skb_array *bands[PFIFO_FAST_BANDS];
 770         int prio;
 771
 772         for (prio = 0; prio < PFIFO_FAST_BANDS; prio++) {
 773                 struct skb_array *q = band2list(priv, prio);
 774
 775                 bands[prio] = q;
 776         }
 777
 778         return skb_array_resize_multiple(bands, PFIFO_FAST_BANDS, new_len,
 779                                          GFP_KERNEL);
 780 }
 781
 782 struct Qdisc_ops pfifo_fast_ops __read_mostly = {
 783         .id             =       "pfifo_fast",
 784         .priv_size      =       sizeof(struct pfifo_fast_priv),
 785         .enqueue        =       pfifo_fast_enqueue,
 786         .dequeue        =       pfifo_fast_dequeue,
 787         .peek           =       pfifo_fast_peek,
 788         .init           =       pfifo_fast_init,
 789         .destroy        =       pfifo_fast_destroy,
 790         .reset          =       pfifo_fast_reset,
 791         .dump           =       pfifo_fast_dump,
 792         .change_tx_queue_len =  pfifo_fast_change_tx_queue_len,
 793         .owner          =       THIS_MODULE,
 794         .static_flags   =       TCQ_F_NOLOCK | TCQ_F_CPUSTATS,
 795 };
 796 EXPORT_SYMBOL(pfifo_fast_ops);
 797
 798 static struct lock_class_key qdisc_tx_busylock;
 799 static struct lock_class_key qdisc_running_key;
 800
 801 struct Qdisc *qdisc_alloc(struct netdev_queue *dev_queue,
 802                           const struct Qdisc_ops *ops,
 803                           struct netlink_ext_ack *extack)
 804 {
 805         struct Qdisc *sch;
 806         unsigned int size = sizeof(*sch) + ops->priv_size;
 807         int err = -ENOBUFS;
 808         struct net_device *dev;
 809
 810         if (!dev_queue) {
 811                 NL_SET_ERR_MSG(extack, "No device queue given");
 812                 err = -EINVAL;
 813                 goto errout;
 814         }
 815
 816         dev = dev_queue->dev;
 817         sch = kzalloc_node(size, GFP_KERNEL, netdev_queue_numa_node_read(dev_queue));
 818
 819         if (!sch)
 820                 goto errout;
 821         __skb_queue_head_init(&sch->gso_skb);
 822         __skb_queue_head_init(&sch->skb_bad_txq);
 823         qdisc_skb_head_init(&sch->q);
 824         spin_lock_init(&sch->q.lock);
 825
 826         if (ops->static_flags & TCQ_F_CPUSTATS) {
 827                 sch->cpu_bstats =
 828                         netdev_alloc_pcpu_stats(struct gnet_stats_basic_cpu);
 829                 if (!sch->cpu_bstats)
 830                         goto errout1;
 831
 832                 sch->cpu_qstats = alloc_percpu(struct gnet_stats_queue);
 833                 if (!sch->cpu_qstats) {
 834                         free_percpu(sch->cpu_bstats);
 835                         goto errout1;
 836                 }
 837         }
 838
 839         spin_lock_init(&sch->busylock);
 840         lockdep_set_class(&sch->busylock,
 841                           dev->qdisc_tx_busylock ?: &qdisc_tx_busylock);
 842
 843         /* seqlock has the same scope of busylock, for NOLOCK qdisc */
 844         spin_lock_init(&sch->seqlock);
 845         lockdep_set_class(&sch->busylock,
 846                           dev->qdisc_tx_busylock ?: &qdisc_tx_busylock);
 847
 848         seqcount_init(&sch->running);
 849         lockdep_set_class(&sch->running,
 850                           dev->qdisc_running_key ?: &qdisc_running_key);
 851
 852         sch->ops = ops;
 853         sch->flags = ops->static_flags;
 854         sch->enqueue = ops->enqueue;
 855         sch->dequeue = ops->dequeue;
 856         sch->dev_queue = dev_queue;
 857         sch->empty = true;
 858         dev_hold(dev);
 859         refcount_set(&sch->refcnt, 1);
 860
 861         return sch;
 862 errout1:
 863         kfree(sch);
 864 errout:
 865         return ERR_PTR(err);
 866 }
 867
 868 struct Qdisc *qdisc_create_dflt(struct netdev_queue *dev_queue,
 869                                 const struct Qdisc_ops *ops,
 870                                 unsigned int parentid,
 871                                 struct netlink_ext_ack *extack)
 872 {
 873         struct Qdisc *sch;
 874
 875         if (!try_module_get(ops->owner)) {
 876                 NL_SET_ERR_MSG(extack, "Failed to increase module reference counter");
 877                 return NULL;
 878         }
 879
 880         sch = qdisc_alloc(dev_queue, ops, extack);
 881         if (IS_ERR(sch)) {
 882                 module_put(ops->owner);
 883                 return NULL;
 884         }
 885         sch->parent = parentid;
 886
 887         if (!ops->init || ops->init(sch, NULL, extack) == 0) {
 888                 trace_qdisc_create(ops, dev_queue->dev, parentid);
 889                 return sch;
 890         }
 891
 892         qdisc_put(sch);
 893         return NULL;
 894 }
 895 EXPORT_SYMBOL(qdisc_create_dflt);
 896
 897 /* Under qdisc_lock(qdisc) and BH! */
 898
 899 void qdisc_reset(struct Qdisc *qdisc)
 900 {
 901         const struct Qdisc_ops *ops = qdisc->ops;
 902         struct sk_buff *skb, *tmp;
 903
 904         trace_qdisc_reset(qdisc);
 905
 906         if (ops->reset)
 907                 ops->reset(qdisc);
 908
 909         skb_queue_walk_safe(&qdisc->gso_skb, skb, tmp) {
 910                 __skb_unlink(skb, &qdisc->gso_skb);
 911                 kfree_skb_list(skb);
 912         }
 913
 914         skb_queue_walk_safe(&qdisc->skb_bad_txq, skb, tmp) {
 915                 __skb_unlink(skb, &qdisc->skb_bad_txq);
 916                 kfree_skb_list(skb);
 917         }
 918
 919         qdisc->q.qlen = 0;
 920         qdisc->qstats.backlog = 0;
 921 }
 922 EXPORT_SYMBOL(qdisc_reset);
 923
 924 void qdisc_free(struct Qdisc *qdisc)
 925 {
 926         if (qdisc_is_percpu_stats(qdisc)) {
 927                 free_percpu(qdisc->cpu_bstats);
 928                 free_percpu(qdisc->cpu_qstats);
 929         }
 930
 931         kfree(qdisc);
 932 }
 933
 934 static void qdisc_free_cb(struct rcu_head *head)
 935 {
 936         struct Qdisc *q = container_of(head, struct Qdisc, rcu);
 937
 938         qdisc_free(q);
 939 }
 940
 941 static void qdisc_destroy(struct Qdisc *qdisc)
 942 {
 943         const struct Qdisc_ops  *ops = qdisc->ops;
 944
 945 #ifdef CONFIG_NET_SCHED
 946         qdisc_hash_del(qdisc);
 947
 948         qdisc_put_stab(rtnl_dereference(qdisc->stab));
 949 #endif
 950         gen_kill_estimator(&qdisc->rate_est);
 951
 952         qdisc_reset(qdisc);
 953
 954         if (ops->destroy)
 955                 ops->destroy(qdisc);
 956
 957         module_put(ops->owner);
 958         dev_put(qdisc_dev(qdisc));
 959
 960         trace_qdisc_destroy(qdisc);
 961
 962         call_rcu(&qdisc->rcu, qdisc_free_cb);
 963 }
 964
 965 void qdisc_put(struct Qdisc *qdisc)
 966 {
 967         if (!qdisc)
 968                 return;
 969
 970         if (qdisc->flags & TCQ_F_BUILTIN ||
 971             !refcount_dec_and_test(&qdisc->refcnt))
 972                 return;
 973
 974         qdisc_destroy(qdisc);
 975 }
 976 EXPORT_SYMBOL(qdisc_put);
 977
 978 /* Version of qdisc_put() that is called with rtnl mutex unlocked.
 979  * Intended to be used as optimization, this function only takes rtnl lock if
 980  * qdisc reference counter reached zero.
 981  */
 982
 983 void qdisc_put_unlocked(struct Qdisc *qdisc)
 984 {
 985         if (qdisc->flags & TCQ_F_BUILTIN ||
 986             !refcount_dec_and_rtnl_lock(&qdisc->refcnt))
 987                 return;
 988
 989         qdisc_destroy(qdisc);
 990         rtnl_unlock();
 991 }
 992 EXPORT_SYMBOL(qdisc_put_unlocked);
 993
 994 /* Attach toplevel qdisc to device queue. */
 995 struct Qdisc *dev_graft_qdisc(struct netdev_queue *dev_queue,
 996                               struct Qdisc *qdisc)
 997 {
 998         struct Qdisc *oqdisc = dev_queue->qdisc_sleeping;
 999         spinlock_t *root_lock;
1000
1001         root_lock = qdisc_lock(oqdisc);
1002         spin_lock_bh(root_lock);
1003
1004         /* ... and graft new one */
1005         if (qdisc == NULL)
1006                 qdisc = &noop_qdisc;
1007         dev_queue->qdisc_sleeping = qdisc;
1008         rcu_assign_pointer(dev_queue->qdisc, &noop_qdisc);
1009
1010         spin_unlock_bh(root_lock);
1011
1012         return oqdisc;
1013 }
1014 EXPORT_SYMBOL(dev_graft_qdisc);
1015
1016 static void attach_one_default_qdisc(struct net_device *dev,
1017                                      struct netdev_queue *dev_queue,
1018                                      void *_unused)
1019 {
1020         struct Qdisc *qdisc;
1021         const struct Qdisc_ops *ops = default_qdisc_ops;
1022
1023         if (dev->priv_flags & IFF_NO_QUEUE)
1024                 ops = &noqueue_qdisc_ops;
1025         else if(dev->type == ARPHRD_CAN)
1026                 ops = &pfifo_fast_ops;
1027
1028         qdisc = qdisc_create_dflt(dev_queue, ops, TC_H_ROOT, NULL);
1029         if (!qdisc)
1030                 return;
1031
1032         if (!netif_is_multiqueue(dev))
1033                 qdisc->flags |= TCQ_F_ONETXQUEUE | TCQ_F_NOPARENT;
1034         dev_queue->qdisc_sleeping = qdisc;
1035 }
1036
1037 static void attach_default_qdiscs(struct net_device *dev)
1038 {
1039         struct netdev_queue *txq;
1040         struct Qdisc *qdisc;
1041
1042         txq = netdev_get_tx_queue(dev, 0);
1043
1044         if (!netif_is_multiqueue(dev) ||
1045             dev->priv_flags & IFF_NO_QUEUE) {
1046                 netdev_for_each_tx_queue(dev, attach_one_default_qdisc, NULL);
1047                 dev->qdisc = txq->qdisc_sleeping;
1048                 qdisc_refcount_inc(dev->qdisc);
1049         } else {
1050                 qdisc = qdisc_create_dflt(txq, &mq_qdisc_ops, TC_H_ROOT, NULL);
1051                 if (qdisc) {
1052                         dev->qdisc = qdisc;
1053                         qdisc->ops->attach(qdisc);
1054                 }
1055         }
1056
1057         /* Detect default qdisc setup/init failed and fallback to "noqueue" */
1058         if (dev->qdisc == &noop_qdisc) {
1059                 netdev_warn(dev, "default qdisc (%s) fail, fallback to %s\n",
1060                             default_qdisc_ops->id, noqueue_qdisc_ops.id);
1061                 dev->priv_flags |= IFF_NO_QUEUE;
1062                 netdev_for_each_tx_queue(dev, attach_one_default_qdisc, NULL);
1063                 dev->qdisc = txq->qdisc_sleeping;
1064                 qdisc_refcount_inc(dev->qdisc);
1065                 dev->priv_flags ^= IFF_NO_QUEUE;
1066         }
1067
1068 #ifdef CONFIG_NET_SCHED
1069         if (dev->qdisc != &noop_qdisc)
1070                 qdisc_hash_add(dev->qdisc, false);
1071 #endif
1072 }
1073
1074 static void transition_one_qdisc(struct net_device *dev,
1075                                  struct netdev_queue *dev_queue,
1076                                  void *_need_watchdog)
1077 {
1078         struct Qdisc *new_qdisc = dev_queue->qdisc_sleeping;
1079         int *need_watchdog_p = _need_watchdog;
1080
1081         if (!(new_qdisc->flags & TCQ_F_BUILTIN))
1082                 clear_bit(__QDISC_STATE_DEACTIVATED, &new_qdisc->state);
1083
1084         rcu_assign_pointer(dev_queue->qdisc, new_qdisc);
1085         if (need_watchdog_p) {
1086                 dev_queue->trans_start = 0;
1087                 *need_watchdog_p = 1;
1088         }
1089 }
1090
1091 void dev_activate(struct net_device *dev)
1092 {
1093         int need_watchdog;
1094
1095         /* No queueing discipline is attached to device;
1096          * create default one for devices, which need queueing
1097          * and noqueue_qdisc for virtual interfaces
1098          */
1099
1100         if (dev->qdisc == &noop_qdisc)
1101                 attach_default_qdiscs(dev);
1102
1103         if (!netif_carrier_ok(dev))
1104                 /* Delay activation until next carrier-on event */
1105                 return;
1106
1107         need_watchdog = 0;
1108         netdev_for_each_tx_queue(dev, transition_one_qdisc, &need_watchdog);
1109         if (dev_ingress_queue(dev))
1110                 transition_one_qdisc(dev, dev_ingress_queue(dev), NULL);
1111
1112         if (need_watchdog) {
1113                 netif_trans_update(dev);
1114                 dev_watchdog_up(dev);
1115         }
1116 }
1117 EXPORT_SYMBOL(dev_activate);
1118
1119 static void qdisc_deactivate(struct Qdisc *qdisc)
1120 {
1121         if (qdisc->flags & TCQ_F_BUILTIN)
1122                 return;
1123
1124         set_bit(__QDISC_STATE_DEACTIVATED, &qdisc->state);
1125 }
1126
1127 static void dev_deactivate_queue(struct net_device *dev,
1128                                  struct netdev_queue *dev_queue,
1129                                  void *_qdisc_default)
1130 {
1131         struct Qdisc *qdisc_default = _qdisc_default;
1132         struct Qdisc *qdisc;
1133
1134         qdisc = rtnl_dereference(dev_queue->qdisc);
1135         if (qdisc) {
1136                 qdisc_deactivate(qdisc);
1137                 rcu_assign_pointer(dev_queue->qdisc, qdisc_default);
1138         }
1139 }
1140
1141 static void dev_reset_queue(struct net_device *dev,
1142                             struct netdev_queue *dev_queue,
1143                             void *_unused)
1144 {
1145         struct Qdisc *qdisc;
1146         bool nolock;
1147
1148         qdisc = dev_queue->qdisc_sleeping;
1149         if (!qdisc)
1150                 return;
1151
1152         nolock = qdisc->flags & TCQ_F_NOLOCK;
1153
1154         if (nolock)
1155                 spin_lock_bh(&qdisc->seqlock);
1156         spin_lock_bh(qdisc_lock(qdisc));
1157
1158         qdisc_reset(qdisc);
1159
1160         spin_unlock_bh(qdisc_lock(qdisc));
1161         if (nolock)
1162                 spin_unlock_bh(&qdisc->seqlock);
1163 }
1164
1165 static bool some_qdisc_is_busy(struct net_device *dev)
1166 {
1167         unsigned int i;
1168
1169         for (i = 0; i < dev->num_tx_queues; i++) {
1170                 struct netdev_queue *dev_queue;
1171                 spinlock_t *root_lock;
1172                 struct Qdisc *q;
1173                 int val;
1174
1175                 dev_queue = netdev_get_tx_queue(dev, i);
1176                 q = dev_queue->qdisc_sleeping;
1177
1178                 root_lock = qdisc_lock(q);
1179                 spin_lock_bh(root_lock);
1180
1181                 val = (qdisc_is_running(q) ||
1182                        test_bit(__QDISC_STATE_SCHED, &q->state));
1183
1184                 spin_unlock_bh(root_lock);
1185
1186                 if (val)
1187                         return true;
1188         }
1189         return false;
1190 }
1191
1192 /**
1193  *      dev_deactivate_many - deactivate transmissions on several devices
1194  *      @head: list of devices to deactivate
1195  *
1196  *      This function returns only when all outstanding transmissions
1197  *      have completed, unless all devices are in dismantle phase.
1198  */
1199 void dev_deactivate_many(struct list_head *head)
1200 {
1201         struct net_device *dev;
1202
1203         list_for_each_entry(dev, head, close_list) {
1204                 netdev_for_each_tx_queue(dev, dev_deactivate_queue,
1205                                          &noop_qdisc);
1206                 if (dev_ingress_queue(dev))
1207                         dev_deactivate_queue(dev, dev_ingress_queue(dev),
1208                                              &noop_qdisc);
1209
1210                 dev_watchdog_down(dev);
1211         }
1212
1213         /* Wait for outstanding qdisc-less dev_queue_xmit calls or
1214          * outstanding qdisc enqueuing calls.
1215          * This is avoided if all devices are in dismantle phase :
1216          * Caller will call synchronize_net() for us
1217          */
1218         synchronize_net();
1219
1220         list_for_each_entry(dev, head, close_list) {
1221                 netdev_for_each_tx_queue(dev, dev_reset_queue, NULL);
1222
1223                 if (dev_ingress_queue(dev))
1224                         dev_reset_queue(dev, dev_ingress_queue(dev), NULL);
1225         }
1226
1227         /* Wait for outstanding qdisc_run calls. */
1228         list_for_each_entry(dev, head, close_list) {
1229                 while (some_qdisc_is_busy(dev)) {
1230                         /* wait_event() would avoid this sleep-loop but would
1231                          * require expensive checks in the fast paths of packet
1232                          * processing which isn't worth it.
1233                          */
1234                         schedule_timeout_uninterruptible(1);
1235                 }
1236         }
1237 }
1238
1239 void dev_deactivate(struct net_device *dev)
1240 {
1241         LIST_HEAD(single);
1242
1243         list_add(&dev->close_list, &single);
1244         dev_deactivate_many(&single);
1245         list_del(&single);
1246 }
1247 EXPORT_SYMBOL(dev_deactivate);
1248
1249 static int qdisc_change_tx_queue_len(struct net_device *dev,
1250                                      struct netdev_queue *dev_queue)
1251 {
1252         struct Qdisc *qdisc = dev_queue->qdisc_sleeping;
1253         const struct Qdisc_ops *ops = qdisc->ops;
1254
1255         if (ops->change_tx_queue_len)
1256                 return ops->change_tx_queue_len(qdisc, dev->tx_queue_len);
1257         return 0;
1258 }
1259
1260 int dev_qdisc_change_tx_queue_len(struct net_device *dev)
1261 {
1262         bool up = dev->flags & IFF_UP;
1263         unsigned int i;
1264         int ret = 0;
1265
1266         if (up)
1267                 dev_deactivate(dev);
1268
1269         for (i = 0; i < dev->num_tx_queues; i++) {
1270                 ret = qdisc_change_tx_queue_len(dev, &dev->_tx[i]);
1271
1272                 /* TODO: revert changes on a partial failure */
1273                 if (ret)
1274                         break;
1275         }
1276
1277         if (up)
1278                 dev_activate(dev);
1279         return ret;
1280 }
1281
1282 static void dev_init_scheduler_queue(struct net_device *dev,
1283                                      struct netdev_queue *dev_queue,
1284                                      void *_qdisc)
1285 {
1286         struct Qdisc *qdisc = _qdisc;
1287
1288         rcu_assign_pointer(dev_queue->qdisc, qdisc);
1289         dev_queue->qdisc_sleeping = qdisc;
1290 }
1291
1292 void dev_init_scheduler(struct net_device *dev)
1293 {
1294         dev->qdisc = &noop_qdisc;
1295         netdev_for_each_tx_queue(dev, dev_init_scheduler_queue, &noop_qdisc);
1296         if (dev_ingress_queue(dev))
1297                 dev_init_scheduler_queue(dev, dev_ingress_queue(dev), &noop_qdisc);
1298
1299         timer_setup(&dev->watchdog_timer, dev_watchdog, 0);
1300 }
1301
1302 static void shutdown_scheduler_queue(struct net_device *dev,
1303                                      struct netdev_queue *dev_queue,
1304                                      void *_qdisc_default)
1305 {
1306         struct Qdisc *qdisc = dev_queue->qdisc_sleeping;
1307         struct Qdisc *qdisc_default = _qdisc_default;
1308
1309         if (qdisc) {
1310                 rcu_assign_pointer(dev_queue->qdisc, qdisc_default);
1311                 dev_queue->qdisc_sleeping = qdisc_default;
1312
1313                 qdisc_put(qdisc);
1314         }
1315 }
1316
1317 void dev_shutdown(struct net_device *dev)
1318 {
1319         netdev_for_each_tx_queue(dev, shutdown_scheduler_queue, &noop_qdisc);
1320         if (dev_ingress_queue(dev))
1321                 shutdown_scheduler_queue(dev, dev_ingress_queue(dev), &noop_qdisc);
1322         qdisc_put(dev->qdisc);
1323         dev->qdisc = &noop_qdisc;
1324
1325         WARN_ON(timer_pending(&dev->watchdog_timer));
1326 }
1327
1328 void psched_ratecfg_precompute(struct psched_ratecfg *r,
1329                                const struct tc_ratespec *conf,
1330                                u64 rate64)
1331 {
1332         memset(r, 0, sizeof(*r));
1333         r->overhead = conf->overhead;
1334         r->rate_bytes_ps = max_t(u64, conf->rate, rate64);
1335         r->linklayer = (conf->linklayer & TC_LINKLAYER_MASK);
1336         r->mult = 1;
1337         /*
1338          * The deal here is to replace a divide by a reciprocal one
1339          * in fast path (a reciprocal divide is a multiply and a shift)
1340          *
1341          * Normal formula would be :
1342          *  time_in_ns = (NSEC_PER_SEC * len) / rate_bps
1343          *
1344          * We compute mult/shift to use instead :
1345          *  time_in_ns = (len * mult) >> shift;
1346          *
1347          * We try to get the highest possible mult value for accuracy,
1348          * but have to make sure no overflows will ever happen.
1349          */
1350         if (r->rate_bytes_ps > 0) {
1351                 u64 factor = NSEC_PER_SEC;
1352
1353                 for (;;) {
1354                         r->mult = div64_u64(factor, r->rate_bytes_ps);
1355                         if (r->mult & (1U << 31) || factor & (1ULL << 63))
1356                                 break;
1357                         factor <<= 1;
1358                         r->shift++;
1359                 }
1360         }
1361 }
1362 EXPORT_SYMBOL(psched_ratecfg_precompute);
1363
1364 static void mini_qdisc_rcu_func(struct rcu_head *head)
1365 {
1366 }
1367
1368 void mini_qdisc_pair_swap(struct mini_Qdisc_pair *miniqp,
1369                           struct tcf_proto *tp_head)
1370 {
1371         /* Protected with chain0->filter_chain_lock.
1372          * Can't access chain directly because tp_head can be NULL.
1373          */
1374         struct mini_Qdisc *miniq_old =
1375                 rcu_dereference_protected(*miniqp->p_miniq, 1);
1376         struct mini_Qdisc *miniq;
1377
1378         if (!tp_head) {
1379                 RCU_INIT_POINTER(*miniqp->p_miniq, NULL);
1380                 /* Wait for flying RCU callback before it is freed. */
1381                 rcu_barrier();
1382                 return;
1383         }
1384
1385         miniq = !miniq_old || miniq_old == &miniqp->miniq2 ?
1386                 &miniqp->miniq1 : &miniqp->miniq2;
1387
1388         /* We need to make sure that readers won't see the miniq
1389          * we are about to modify. So wait until previous call_rcu callback
1390          * is done.
1391          */
1392         rcu_barrier();
1393         miniq->filter_list = tp_head;
1394         rcu_assign_pointer(*miniqp->p_miniq, miniq);
1395
1396         if (miniq_old)
1397                 /* This is counterpart of the rcu barriers above. We need to
1398                  * block potential new user of miniq_old until all readers
1399                  * are not seeing it.
1400                  */
1401                 call_rcu(&miniq_old->rcu, mini_qdisc_rcu_func);
1402 }
1403 EXPORT_SYMBOL(mini_qdisc_pair_swap);
1404
1405 void mini_qdisc_pair_block_init(struct mini_Qdisc_pair *miniqp,
1406                                 struct tcf_block *block)
1407 {
1408         miniqp->miniq1.block = block;
1409         miniqp->miniq2.block = block;
1410 }
1411 EXPORT_SYMBOL(mini_qdisc_pair_block_init);
1412
1413 void mini_qdisc_pair_init(struct mini_Qdisc_pair *miniqp, struct Qdisc *qdisc,
1414                           struct mini_Qdisc __rcu **p_miniq)
1415 {
1416         miniqp->miniq1.cpu_bstats = qdisc->cpu_bstats;
1417         miniqp->miniq1.cpu_qstats = qdisc->cpu_qstats;
1418         miniqp->miniq2.cpu_bstats = qdisc->cpu_bstats;
1419         miniqp->miniq2.cpu_qstats = qdisc->cpu_qstats;
1420         miniqp->p_miniq = p_miniq;
1421 }
1422 EXPORT_SYMBOL(mini_qdisc_pair_init);