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 static void qdisc_maybe_clear_missed(struct Qdisc *q,
  39                                      const struct netdev_queue *txq)
  40 {
  41         clear_bit(__QDISC_STATE_MISSED, &q->state);
  42
  43         /* Make sure the below netif_xmit_frozen_or_stopped()
  44          * checking happens after clearing STATE_MISSED.
  45          */
  46         smp_mb__after_atomic();
  47
  48         /* Checking netif_xmit_frozen_or_stopped() again to
  49          * make sure STATE_MISSED is set if the STATE_MISSED
  50          * set by netif_tx_wake_queue()'s rescheduling of
  51          * net_tx_action() is cleared by the above clear_bit().
  52          */
  53         if (!netif_xmit_frozen_or_stopped(txq))
  54                 set_bit(__QDISC_STATE_MISSED, &q->state);
  55         else
  56                 set_bit(__QDISC_STATE_DRAINING, &q->state);
  57 }
  58
  59 /* Main transmission queue. */
  60
  61 /* Modifications to data participating in scheduling must be protected with
  62  * qdisc_lock(qdisc) spinlock.
  63  *
  64  * The idea is the following:
  65  * - enqueue, dequeue are serialized via qdisc root lock
  66  * - ingress filtering is also serialized via qdisc root lock
  67  * - updates to tree and tree walking are only done under the rtnl mutex.
  68  */
  69
  70 #define SKB_XOFF_MAGIC ((struct sk_buff *)1UL)
  71
  72 static inline struct sk_buff *__skb_dequeue_bad_txq(struct Qdisc *q)
  73 {
  74         const struct netdev_queue *txq = q->dev_queue;
  75         spinlock_t *lock = NULL;
  76         struct sk_buff *skb;
  77
  78         if (q->flags & TCQ_F_NOLOCK) {
  79                 lock = qdisc_lock(q);
  80                 spin_lock(lock);
  81         }
  82
  83         skb = skb_peek(&q->skb_bad_txq);
  84         if (skb) {
  85                 /* check the reason of requeuing without tx lock first */
  86                 txq = skb_get_tx_queue(txq->dev, skb);
  87                 if (!netif_xmit_frozen_or_stopped(txq)) {
  88                         skb = __skb_dequeue(&q->skb_bad_txq);
  89                         if (qdisc_is_percpu_stats(q)) {
  90                                 qdisc_qstats_cpu_backlog_dec(q, skb);
  91                                 qdisc_qstats_cpu_qlen_dec(q);
  92                         } else {
  93                                 qdisc_qstats_backlog_dec(q, skb);
  94                                 q->q.qlen--;
  95                         }
  96                 } else {
  97                         skb = SKB_XOFF_MAGIC;
  98                         qdisc_maybe_clear_missed(q, txq);
  99                 }
 100         }
 101
 102         if (lock)
 103                 spin_unlock(lock);
 104
 105         return skb;
 106 }
 107
 108 static inline struct sk_buff *qdisc_dequeue_skb_bad_txq(struct Qdisc *q)
 109 {
 110         struct sk_buff *skb = skb_peek(&q->skb_bad_txq);
 111
 112         if (unlikely(skb))
 113                 skb = __skb_dequeue_bad_txq(q);
 114
 115         return skb;
 116 }
 117
 118 static inline void qdisc_enqueue_skb_bad_txq(struct Qdisc *q,
 119                                              struct sk_buff *skb)
 120 {
 121         spinlock_t *lock = NULL;
 122
 123         if (q->flags & TCQ_F_NOLOCK) {
 124                 lock = qdisc_lock(q);
 125                 spin_lock(lock);
 126         }
 127
 128         __skb_queue_tail(&q->skb_bad_txq, skb);
 129
 130         if (qdisc_is_percpu_stats(q)) {
 131                 qdisc_qstats_cpu_backlog_inc(q, skb);
 132                 qdisc_qstats_cpu_qlen_inc(q);
 133         } else {
 134                 qdisc_qstats_backlog_inc(q, skb);
 135                 q->q.qlen++;
 136         }
 137
 138         if (lock)
 139                 spin_unlock(lock);
 140 }
 141
 142 static inline void dev_requeue_skb(struct sk_buff *skb, struct Qdisc *q)
 143 {
 144         spinlock_t *lock = NULL;
 145
 146         if (q->flags & TCQ_F_NOLOCK) {
 147                 lock = qdisc_lock(q);
 148                 spin_lock(lock);
 149         }
 150
 151         while (skb) {
 152                 struct sk_buff *next = skb->next;
 153
 154                 __skb_queue_tail(&q->gso_skb, skb);
 155
 156                 /* it's still part of the queue */
 157                 if (qdisc_is_percpu_stats(q)) {
 158                         qdisc_qstats_cpu_requeues_inc(q);
 159                         qdisc_qstats_cpu_backlog_inc(q, skb);
 160                         qdisc_qstats_cpu_qlen_inc(q);
 161                 } else {
 162                         q->qstats.requeues++;
 163                         qdisc_qstats_backlog_inc(q, skb);
 164                         q->q.qlen++;
 165                 }
 166
 167                 skb = next;
 168         }
 169
 170         if (lock) {
 171                 spin_unlock(lock);
 172                 set_bit(__QDISC_STATE_MISSED, &q->state);
 173         } else {
 174                 __netif_schedule(q);
 175         }
 176 }
 177
 178 static void try_bulk_dequeue_skb(struct Qdisc *q,
 179                                  struct sk_buff *skb,
 180                                  const struct netdev_queue *txq,
 181                                  int *packets)
 182 {
 183         int bytelimit = qdisc_avail_bulklimit(txq) - skb->len;
 184
 185         while (bytelimit > 0) {
 186                 struct sk_buff *nskb = q->dequeue(q);
 187
 188                 if (!nskb)
 189                         break;
 190
 191                 bytelimit -= nskb->len; /* covers GSO len */
 192                 skb->next = nskb;
 193                 skb = nskb;
 194                 (*packets)++; /* GSO counts as one pkt */
 195         }
 196         skb_mark_not_on_list(skb);
 197 }
 198
 199 /* This variant of try_bulk_dequeue_skb() makes sure
 200  * all skbs in the chain are for the same txq
 201  */
 202 static void try_bulk_dequeue_skb_slow(struct Qdisc *q,
 203                                       struct sk_buff *skb,
 204                                       int *packets)
 205 {
 206         int mapping = skb_get_queue_mapping(skb);
 207         struct sk_buff *nskb;
 208         int cnt = 0;
 209
 210         do {
 211                 nskb = q->dequeue(q);
 212                 if (!nskb)
 213                         break;
 214                 if (unlikely(skb_get_queue_mapping(nskb) != mapping)) {
 215                         qdisc_enqueue_skb_bad_txq(q, nskb);
 216                         break;
 217                 }
 218                 skb->next = nskb;
 219                 skb = nskb;
 220         } while (++cnt < 8);
 221         (*packets) += cnt;
 222         skb_mark_not_on_list(skb);
 223 }
 224
 225 /* Note that dequeue_skb can possibly return a SKB list (via skb->next).
 226  * A requeued skb (via q->gso_skb) can also be a SKB list.
 227  */
 228 static struct sk_buff *dequeue_skb(struct Qdisc *q, bool *validate,
 229                                    int *packets)
 230 {
 231         const struct netdev_queue *txq = q->dev_queue;
 232         struct sk_buff *skb = NULL;
 233
 234         *packets = 1;
 235         if (unlikely(!skb_queue_empty(&q->gso_skb))) {
 236                 spinlock_t *lock = NULL;
 237
 238                 if (q->flags & TCQ_F_NOLOCK) {
 239                         lock = qdisc_lock(q);
 240                         spin_lock(lock);
 241                 }
 242
 243                 skb = skb_peek(&q->gso_skb);
 244
 245                 /* skb may be null if another cpu pulls gso_skb off in between
 246                  * empty check and lock.
 247                  */
 248                 if (!skb) {
 249                         if (lock)
 250                                 spin_unlock(lock);
 251                         goto validate;
 252                 }
 253
 254                 /* skb in gso_skb were already validated */
 255                 *validate = false;
 256                 if (xfrm_offload(skb))
 257                         *validate = true;
 258                 /* check the reason of requeuing without tx lock first */
 259                 txq = skb_get_tx_queue(txq->dev, skb);
 260                 if (!netif_xmit_frozen_or_stopped(txq)) {
 261                         skb = __skb_dequeue(&q->gso_skb);
 262                         if (qdisc_is_percpu_stats(q)) {
 263                                 qdisc_qstats_cpu_backlog_dec(q, skb);
 264                                 qdisc_qstats_cpu_qlen_dec(q);
 265                         } else {
 266                                 qdisc_qstats_backlog_dec(q, skb);
 267                                 q->q.qlen--;
 268                         }
 269                 } else {
 270                         skb = NULL;
 271                         qdisc_maybe_clear_missed(q, txq);
 272                 }
 273                 if (lock)
 274                         spin_unlock(lock);
 275                 goto trace;
 276         }
 277 validate:
 278         *validate = true;
 279
 280         if ((q->flags & TCQ_F_ONETXQUEUE) &&
 281             netif_xmit_frozen_or_stopped(txq)) {
 282                 qdisc_maybe_clear_missed(q, txq);
 283                 return skb;
 284         }
 285
 286         skb = qdisc_dequeue_skb_bad_txq(q);
 287         if (unlikely(skb)) {
 288                 if (skb == SKB_XOFF_MAGIC)
 289                         return NULL;
 290                 goto bulk;
 291         }
 292         skb = q->dequeue(q);
 293         if (skb) {
 294 bulk:
 295                 if (qdisc_may_bulk(q))
 296                         try_bulk_dequeue_skb(q, skb, txq, packets);
 297                 else
 298                         try_bulk_dequeue_skb_slow(q, skb, packets);
 299         }
 300 trace:
 301         trace_qdisc_dequeue(q, txq, *packets, skb);
 302         return skb;
 303 }
 304
 305 /*
 306  * Transmit possibly several skbs, and handle the return status as
 307  * required. Owning qdisc running bit guarantees that only one CPU
 308  * can execute this function.
 309  *
 310  * Returns to the caller:
 311  *                              false  - hardware queue frozen backoff
 312  *                              true   - feel free to send more pkts
 313  */
 314 bool sch_direct_xmit(struct sk_buff *skb, struct Qdisc *q,
 315                      struct net_device *dev, struct netdev_queue *txq,
 316                      spinlock_t *root_lock, bool validate)
 317 {
 318         int ret = NETDEV_TX_BUSY;
 319         bool again = false;
 320
 321         /* And release qdisc */
 322         if (root_lock)
 323                 spin_unlock(root_lock);
 324
 325         /* Note that we validate skb (GSO, checksum, ...) outside of locks */
 326         if (validate)
 327                 skb = validate_xmit_skb_list(skb, dev, &again);
 328
 329 #ifdef CONFIG_XFRM_OFFLOAD
 330         if (unlikely(again)) {
 331                 if (root_lock)
 332                         spin_lock(root_lock);
 333
 334                 dev_requeue_skb(skb, q);
 335                 return false;
 336         }
 337 #endif
 338
 339         if (likely(skb)) {
 340                 HARD_TX_LOCK(dev, txq, smp_processor_id());
 341                 if (!netif_xmit_frozen_or_stopped(txq))
 342                         skb = dev_hard_start_xmit(skb, dev, txq, &ret);
 343                 else
 344                         qdisc_maybe_clear_missed(q, txq);
 345
 346                 HARD_TX_UNLOCK(dev, txq);
 347         } else {
 348                 if (root_lock)
 349                         spin_lock(root_lock);
 350                 return true;
 351         }
 352
 353         if (root_lock)
 354                 spin_lock(root_lock);
 355
 356         if (!dev_xmit_complete(ret)) {
 357                 /* Driver returned NETDEV_TX_BUSY - requeue skb */
 358                 if (unlikely(ret != NETDEV_TX_BUSY))
 359                         net_warn_ratelimited("BUG %s code %d qlen %d\n",
 360                                              dev->name, ret, q->q.qlen);
 361
 362                 dev_requeue_skb(skb, q);
 363                 return false;
 364         }
 365
 366         return true;
 367 }
 368
 369 /*
 370  * NOTE: Called under qdisc_lock(q) with locally disabled BH.
 371  *
 372  * running seqcount guarantees only one CPU can process
 373  * this qdisc at a time. qdisc_lock(q) serializes queue accesses for
 374  * this queue.
 375  *
 376  *  netif_tx_lock serializes accesses to device driver.
 377  *
 378  *  qdisc_lock(q) and netif_tx_lock are mutually exclusive,
 379  *  if one is grabbed, another must be free.
 380  *
 381  * Note, that this procedure can be called by a watchdog timer
 382  *
 383  * Returns to the caller:
 384  *                              0  - queue is empty or throttled.
 385  *                              >0 - queue is not empty.
 386  *
 387  */
 388 static inline bool qdisc_restart(struct Qdisc *q, int *packets)
 389 {
 390         spinlock_t *root_lock = NULL;
 391         struct netdev_queue *txq;
 392         struct net_device *dev;
 393         struct sk_buff *skb;
 394         bool validate;
 395
 396         /* Dequeue packet */
 397         skb = dequeue_skb(q, &validate, packets);
 398         if (unlikely(!skb))
 399                 return false;
 400
 401         if (!(q->flags & TCQ_F_NOLOCK))
 402                 root_lock = qdisc_lock(q);
 403
 404         dev = qdisc_dev(q);
 405         txq = skb_get_tx_queue(dev, skb);
 406
 407         return sch_direct_xmit(skb, q, dev, txq, root_lock, validate);
 408 }
 409
 410 void __qdisc_run(struct Qdisc *q)
 411 {
 412         int quota = dev_tx_weight;
 413         int packets;
 414
 415         while (qdisc_restart(q, &packets)) {
 416                 quota -= packets;
 417                 if (quota <= 0) {
 418                         if (q->flags & TCQ_F_NOLOCK)
 419                                 set_bit(__QDISC_STATE_MISSED, &q->state);
 420                         else
 421                                 __netif_schedule(q);
 422
 423                         break;
 424                 }
 425         }
 426 }
 427
 428 unsigned long dev_trans_start(struct net_device *dev)
 429 {
 430         unsigned long val, res;
 431         unsigned int i;
 432
 433         if (is_vlan_dev(dev))
 434                 dev = vlan_dev_real_dev(dev);
 435         else if (netif_is_macvlan(dev))
 436                 dev = macvlan_dev_real_dev(dev);
 437         res = READ_ONCE(netdev_get_tx_queue(dev, 0)->trans_start);
 438         for (i = 1; i < dev->num_tx_queues; i++) {
 439                 val = READ_ONCE(netdev_get_tx_queue(dev, i)->trans_start);
 440                 if (val && time_after(val, res))
 441                         res = val;
 442         }
 443
 444         return res;
 445 }
 446 EXPORT_SYMBOL(dev_trans_start);
 447
 448 static void netif_freeze_queues(struct net_device *dev)
 449 {
 450         unsigned int i;
 451         int cpu;
 452
 453         cpu = smp_processor_id();
 454         for (i = 0; i < dev->num_tx_queues; i++) {
 455                 struct netdev_queue *txq = netdev_get_tx_queue(dev, i);
 456
 457                 /* We are the only thread of execution doing a
 458                  * freeze, but we have to grab the _xmit_lock in
 459                  * order to synchronize with threads which are in
 460                  * the ->hard_start_xmit() handler and already
 461                  * checked the frozen bit.
 462                  */
 463                 __netif_tx_lock(txq, cpu);
 464                 set_bit(__QUEUE_STATE_FROZEN, &txq->state);
 465                 __netif_tx_unlock(txq);
 466         }
 467 }
 468
 469 void netif_tx_lock(struct net_device *dev)
 470 {
 471         spin_lock(&dev->tx_global_lock);
 472         netif_freeze_queues(dev);
 473 }
 474 EXPORT_SYMBOL(netif_tx_lock);
 475
 476 static void netif_unfreeze_queues(struct net_device *dev)
 477 {
 478         unsigned int i;
 479
 480         for (i = 0; i < dev->num_tx_queues; i++) {
 481                 struct netdev_queue *txq = netdev_get_tx_queue(dev, i);
 482
 483                 /* No need to grab the _xmit_lock here.  If the
 484                  * queue is not stopped for another reason, we
 485                  * force a schedule.
 486                  */
 487                 clear_bit(__QUEUE_STATE_FROZEN, &txq->state);
 488                 netif_schedule_queue(txq);
 489         }
 490 }
 491
 492 void netif_tx_unlock(struct net_device *dev)
 493 {
 494         netif_unfreeze_queues(dev);
 495         spin_unlock(&dev->tx_global_lock);
 496 }
 497 EXPORT_SYMBOL(netif_tx_unlock);
 498
 499 static void dev_watchdog(struct timer_list *t)
 500 {
 501         struct net_device *dev = from_timer(dev, t, watchdog_timer);
 502         bool release = true;
 503
 504         spin_lock(&dev->tx_global_lock);
 505         if (!qdisc_tx_is_noop(dev)) {
 506                 if (netif_device_present(dev) &&
 507                     netif_running(dev) &&
 508                     netif_carrier_ok(dev)) {
 509                         int some_queue_timedout = 0;
 510                         unsigned int i;
 511                         unsigned long trans_start;
 512
 513                         for (i = 0; i < dev->num_tx_queues; i++) {
 514                                 struct netdev_queue *txq;
 515
 516                                 txq = netdev_get_tx_queue(dev, i);
 517                                 trans_start = READ_ONCE(txq->trans_start);
 518                                 if (netif_xmit_stopped(txq) &&
 519                                     time_after(jiffies, (trans_start +
 520                                                          dev->watchdog_timeo))) {
 521                                         some_queue_timedout = 1;
 522                                         atomic_long_inc(&txq->trans_timeout);
 523                                         break;
 524                                 }
 525                         }
 526
 527                         if (unlikely(some_queue_timedout)) {
 528                                 trace_net_dev_xmit_timeout(dev, i);
 529                                 WARN_ONCE(1, KERN_INFO "NETDEV WATCHDOG: %s (%s): transmit queue %u timed out\n",
 530                                        dev->name, netdev_drivername(dev), i);
 531                                 netif_freeze_queues(dev);
 532                                 dev->netdev_ops->ndo_tx_timeout(dev, i);
 533                                 netif_unfreeze_queues(dev);
 534                         }
 535                         if (!mod_timer(&dev->watchdog_timer,
 536                                        round_jiffies(jiffies +
 537                                                      dev->watchdog_timeo)))
 538                                 release = false;
 539                 }
 540         }
 541         spin_unlock(&dev->tx_global_lock);
 542
 543         if (release)
 544                 netdev_put(dev, &dev->watchdog_dev_tracker);
 545 }
 546
 547 void __netdev_watchdog_up(struct net_device *dev)
 548 {
 549         if (dev->netdev_ops->ndo_tx_timeout) {
 550                 if (dev->watchdog_timeo <= 0)
 551                         dev->watchdog_timeo = 5*HZ;
 552                 if (!mod_timer(&dev->watchdog_timer,
 553                                round_jiffies(jiffies + dev->watchdog_timeo)))
 554                         netdev_hold(dev, &dev->watchdog_dev_tracker,
 555                                     GFP_ATOMIC);
 556         }
 557 }
 558 EXPORT_SYMBOL_GPL(__netdev_watchdog_up);
 559
 560 static void dev_watchdog_up(struct net_device *dev)
 561 {
 562         __netdev_watchdog_up(dev);
 563 }
 564
 565 static void dev_watchdog_down(struct net_device *dev)
 566 {
 567         netif_tx_lock_bh(dev);
 568         if (del_timer(&dev->watchdog_timer))
 569                 netdev_put(dev, &dev->watchdog_dev_tracker);
 570         netif_tx_unlock_bh(dev);
 571 }
 572
 573 /**
 574  *      netif_carrier_on - set carrier
 575  *      @dev: network device
 576  *
 577  * Device has detected acquisition of carrier.
 578  */
 579 void netif_carrier_on(struct net_device *dev)
 580 {
 581         if (test_and_clear_bit(__LINK_STATE_NOCARRIER, &dev->state)) {
 582                 if (dev->reg_state == NETREG_UNINITIALIZED)
 583                         return;
 584                 atomic_inc(&dev->carrier_up_count);
 585                 linkwatch_fire_event(dev);
 586                 if (netif_running(dev))
 587                         __netdev_watchdog_up(dev);
 588         }
 589 }
 590 EXPORT_SYMBOL(netif_carrier_on);
 591
 592 /**
 593  *      netif_carrier_off - clear carrier
 594  *      @dev: network device
 595  *
 596  * Device has detected loss of carrier.
 597  */
 598 void netif_carrier_off(struct net_device *dev)
 599 {
 600         if (!test_and_set_bit(__LINK_STATE_NOCARRIER, &dev->state)) {
 601                 if (dev->reg_state == NETREG_UNINITIALIZED)
 602                         return;
 603                 atomic_inc(&dev->carrier_down_count);
 604                 linkwatch_fire_event(dev);
 605         }
 606 }
 607 EXPORT_SYMBOL(netif_carrier_off);
 608
 609 /**
 610  *      netif_carrier_event - report carrier state event
 611  *      @dev: network device
 612  *
 613  * Device has detected a carrier event but the carrier state wasn't changed.
 614  * Use in drivers when querying carrier state asynchronously, to avoid missing
 615  * events (link flaps) if link recovers before it's queried.
 616  */
 617 void netif_carrier_event(struct net_device *dev)
 618 {
 619         if (dev->reg_state == NETREG_UNINITIALIZED)
 620                 return;
 621         atomic_inc(&dev->carrier_up_count);
 622         atomic_inc(&dev->carrier_down_count);
 623         linkwatch_fire_event(dev);
 624 }
 625 EXPORT_SYMBOL_GPL(netif_carrier_event);
 626
 627 /* "NOOP" scheduler: the best scheduler, recommended for all interfaces
 628    under all circumstances. It is difficult to invent anything faster or
 629    cheaper.
 630  */
 631
 632 static int noop_enqueue(struct sk_buff *skb, struct Qdisc *qdisc,
 633                         struct sk_buff **to_free)
 634 {
 635         __qdisc_drop(skb, to_free);
 636         return NET_XMIT_CN;
 637 }
 638
 639 static struct sk_buff *noop_dequeue(struct Qdisc *qdisc)
 640 {
 641         return NULL;
 642 }
 643
 644 struct Qdisc_ops noop_qdisc_ops __read_mostly = {
 645         .id             =       "noop",
 646         .priv_size      =       0,
 647         .enqueue        =       noop_enqueue,
 648         .dequeue        =       noop_dequeue,
 649         .peek           =       noop_dequeue,
 650         .owner          =       THIS_MODULE,
 651 };
 652
 653 static struct netdev_queue noop_netdev_queue = {
 654         RCU_POINTER_INITIALIZER(qdisc, &noop_qdisc),
 655         .qdisc_sleeping =       &noop_qdisc,
 656 };
 657
 658 struct Qdisc noop_qdisc = {
 659         .enqueue        =       noop_enqueue,
 660         .dequeue        =       noop_dequeue,
 661         .flags          =       TCQ_F_BUILTIN,
 662         .ops            =       &noop_qdisc_ops,
 663         .q.lock         =       __SPIN_LOCK_UNLOCKED(noop_qdisc.q.lock),
 664         .dev_queue      =       &noop_netdev_queue,
 665         .busylock       =       __SPIN_LOCK_UNLOCKED(noop_qdisc.busylock),
 666         .gso_skb = {
 667                 .next = (struct sk_buff *)&noop_qdisc.gso_skb,
 668                 .prev = (struct sk_buff *)&noop_qdisc.gso_skb,
 669                 .qlen = 0,
 670                 .lock = __SPIN_LOCK_UNLOCKED(noop_qdisc.gso_skb.lock),
 671         },
 672         .skb_bad_txq = {
 673                 .next = (struct sk_buff *)&noop_qdisc.skb_bad_txq,
 674                 .prev = (struct sk_buff *)&noop_qdisc.skb_bad_txq,
 675                 .qlen = 0,
 676                 .lock = __SPIN_LOCK_UNLOCKED(noop_qdisc.skb_bad_txq.lock),
 677         },
 678 };
 679 EXPORT_SYMBOL(noop_qdisc);
 680
 681 static int noqueue_init(struct Qdisc *qdisc, struct nlattr *opt,
 682                         struct netlink_ext_ack *extack)
 683 {
 684         /* register_qdisc() assigns a default of noop_enqueue if unset,
 685          * but __dev_queue_xmit() treats noqueue only as such
 686          * if this is NULL - so clear it here. */
 687         qdisc->enqueue = NULL;
 688         return 0;
 689 }
 690
 691 struct Qdisc_ops noqueue_qdisc_ops __read_mostly = {
 692         .id             =       "noqueue",
 693         .priv_size      =       0,
 694         .init           =       noqueue_init,
 695         .enqueue        =       noop_enqueue,
 696         .dequeue        =       noop_dequeue,
 697         .peek           =       noop_dequeue,
 698         .owner          =       THIS_MODULE,
 699 };
 700
 701 static const u8 prio2band[TC_PRIO_MAX + 1] = {
 702         1, 2, 2, 2, 1, 2, 0, 0 , 1, 1, 1, 1, 1, 1, 1, 1
 703 };
 704
 705 /* 3-band FIFO queue: old style, but should be a bit faster than
 706    generic prio+fifo combination.
 707  */
 708
 709 #define PFIFO_FAST_BANDS 3
 710
 711 /*
 712  * Private data for a pfifo_fast scheduler containing:
 713  *      - rings for priority bands
 714  */
 715 struct pfifo_fast_priv {
 716         struct skb_array q[PFIFO_FAST_BANDS];
 717 };
 718
 719 static inline struct skb_array *band2list(struct pfifo_fast_priv *priv,
 720                                           int band)
 721 {
 722         return &priv->q[band];
 723 }
 724
 725 static int pfifo_fast_enqueue(struct sk_buff *skb, struct Qdisc *qdisc,
 726                               struct sk_buff **to_free)
 727 {
 728         int band = prio2band[skb->priority & TC_PRIO_MAX];
 729         struct pfifo_fast_priv *priv = qdisc_priv(qdisc);
 730         struct skb_array *q = band2list(priv, band);
 731         unsigned int pkt_len = qdisc_pkt_len(skb);
 732         int err;
 733
 734         err = skb_array_produce(q, skb);
 735
 736         if (unlikely(err)) {
 737                 if (qdisc_is_percpu_stats(qdisc))
 738                         return qdisc_drop_cpu(skb, qdisc, to_free);
 739                 else
 740                         return qdisc_drop(skb, qdisc, to_free);
 741         }
 742
 743         qdisc_update_stats_at_enqueue(qdisc, pkt_len);
 744         return NET_XMIT_SUCCESS;
 745 }
 746
 747 static struct sk_buff *pfifo_fast_dequeue(struct Qdisc *qdisc)
 748 {
 749         struct pfifo_fast_priv *priv = qdisc_priv(qdisc);
 750         struct sk_buff *skb = NULL;
 751         bool need_retry = true;
 752         int band;
 753
 754 retry:
 755         for (band = 0; band < PFIFO_FAST_BANDS && !skb; band++) {
 756                 struct skb_array *q = band2list(priv, band);
 757
 758                 if (__skb_array_empty(q))
 759                         continue;
 760
 761                 skb = __skb_array_consume(q);
 762         }
 763         if (likely(skb)) {
 764                 qdisc_update_stats_at_dequeue(qdisc, skb);
 765         } else if (need_retry &&
 766                    READ_ONCE(qdisc->state) & QDISC_STATE_NON_EMPTY) {
 767                 /* Delay clearing the STATE_MISSED here to reduce
 768                  * the overhead of the second spin_trylock() in
 769                  * qdisc_run_begin() and __netif_schedule() calling
 770                  * in qdisc_run_end().
 771                  */
 772                 clear_bit(__QDISC_STATE_MISSED, &qdisc->state);
 773                 clear_bit(__QDISC_STATE_DRAINING, &qdisc->state);
 774
 775                 /* Make sure dequeuing happens after clearing
 776                  * STATE_MISSED.
 777                  */
 778                 smp_mb__after_atomic();
 779
 780                 need_retry = false;
 781
 782                 goto retry;
 783         }
 784
 785         return skb;
 786 }
 787
 788 static struct sk_buff *pfifo_fast_peek(struct Qdisc *qdisc)
 789 {
 790         struct pfifo_fast_priv *priv = qdisc_priv(qdisc);
 791         struct sk_buff *skb = NULL;
 792         int band;
 793
 794         for (band = 0; band < PFIFO_FAST_BANDS && !skb; band++) {
 795                 struct skb_array *q = band2list(priv, band);
 796
 797                 skb = __skb_array_peek(q);
 798         }
 799
 800         return skb;
 801 }
 802
 803 static void pfifo_fast_reset(struct Qdisc *qdisc)
 804 {
 805         int i, band;
 806         struct pfifo_fast_priv *priv = qdisc_priv(qdisc);
 807
 808         for (band = 0; band < PFIFO_FAST_BANDS; band++) {
 809                 struct skb_array *q = band2list(priv, band);
 810                 struct sk_buff *skb;
 811
 812                 /* NULL ring is possible if destroy path is due to a failed
 813                  * skb_array_init() in pfifo_fast_init() case.
 814                  */
 815                 if (!q->ring.queue)
 816                         continue;
 817
 818                 while ((skb = __skb_array_consume(q)) != NULL)
 819                         kfree_skb(skb);
 820         }
 821
 822         if (qdisc_is_percpu_stats(qdisc)) {
 823                 for_each_possible_cpu(i) {
 824                         struct gnet_stats_queue *q;
 825
 826                         q = per_cpu_ptr(qdisc->cpu_qstats, i);
 827                         q->backlog = 0;
 828                         q->qlen = 0;
 829                 }
 830         }
 831 }
 832
 833 static int pfifo_fast_dump(struct Qdisc *qdisc, struct sk_buff *skb)
 834 {
 835         struct tc_prio_qopt opt = { .bands = PFIFO_FAST_BANDS };
 836
 837         memcpy(&opt.priomap, prio2band, TC_PRIO_MAX + 1);
 838         if (nla_put(skb, TCA_OPTIONS, sizeof(opt), &opt))
 839                 goto nla_put_failure;
 840         return skb->len;
 841
 842 nla_put_failure:
 843         return -1;
 844 }
 845
 846 static int pfifo_fast_init(struct Qdisc *qdisc, struct nlattr *opt,
 847                            struct netlink_ext_ack *extack)
 848 {
 849         unsigned int qlen = qdisc_dev(qdisc)->tx_queue_len;
 850         struct pfifo_fast_priv *priv = qdisc_priv(qdisc);
 851         int prio;
 852
 853         /* guard against zero length rings */
 854         if (!qlen)
 855                 return -EINVAL;
 856
 857         for (prio = 0; prio < PFIFO_FAST_BANDS; prio++) {
 858                 struct skb_array *q = band2list(priv, prio);
 859                 int err;
 860
 861                 err = skb_array_init(q, qlen, GFP_KERNEL);
 862                 if (err)
 863                         return -ENOMEM;
 864         }
 865
 866         /* Can by-pass the queue discipline */
 867         qdisc->flags |= TCQ_F_CAN_BYPASS;
 868         return 0;
 869 }
 870
 871 static void pfifo_fast_destroy(struct Qdisc *sch)
 872 {
 873         struct pfifo_fast_priv *priv = qdisc_priv(sch);
 874         int prio;
 875
 876         for (prio = 0; prio < PFIFO_FAST_BANDS; prio++) {
 877                 struct skb_array *q = band2list(priv, prio);
 878
 879                 /* NULL ring is possible if destroy path is due to a failed
 880                  * skb_array_init() in pfifo_fast_init() case.
 881                  */
 882                 if (!q->ring.queue)
 883                         continue;
 884                 /* Destroy ring but no need to kfree_skb because a call to
 885                  * pfifo_fast_reset() has already done that work.
 886                  */
 887                 ptr_ring_cleanup(&q->ring, NULL);
 888         }
 889 }
 890
 891 static int pfifo_fast_change_tx_queue_len(struct Qdisc *sch,
 892                                           unsigned int new_len)
 893 {
 894         struct pfifo_fast_priv *priv = qdisc_priv(sch);
 895         struct skb_array *bands[PFIFO_FAST_BANDS];
 896         int prio;
 897
 898         for (prio = 0; prio < PFIFO_FAST_BANDS; prio++) {
 899                 struct skb_array *q = band2list(priv, prio);
 900
 901                 bands[prio] = q;
 902         }
 903
 904         return skb_array_resize_multiple(bands, PFIFO_FAST_BANDS, new_len,
 905                                          GFP_KERNEL);
 906 }
 907
 908 struct Qdisc_ops pfifo_fast_ops __read_mostly = {
 909         .id             =       "pfifo_fast",
 910         .priv_size      =       sizeof(struct pfifo_fast_priv),
 911         .enqueue        =       pfifo_fast_enqueue,
 912         .dequeue        =       pfifo_fast_dequeue,
 913         .peek           =       pfifo_fast_peek,
 914         .init           =       pfifo_fast_init,
 915         .destroy        =       pfifo_fast_destroy,
 916         .reset          =       pfifo_fast_reset,
 917         .dump           =       pfifo_fast_dump,
 918         .change_tx_queue_len =  pfifo_fast_change_tx_queue_len,
 919         .owner          =       THIS_MODULE,
 920         .static_flags   =       TCQ_F_NOLOCK | TCQ_F_CPUSTATS,
 921 };
 922 EXPORT_SYMBOL(pfifo_fast_ops);
 923
 924 static struct lock_class_key qdisc_tx_busylock;
 925
 926 struct Qdisc *qdisc_alloc(struct netdev_queue *dev_queue,
 927                           const struct Qdisc_ops *ops,
 928                           struct netlink_ext_ack *extack)
 929 {
 930         struct Qdisc *sch;
 931         unsigned int size = sizeof(*sch) + ops->priv_size;
 932         int err = -ENOBUFS;
 933         struct net_device *dev;
 934
 935         if (!dev_queue) {
 936                 NL_SET_ERR_MSG(extack, "No device queue given");
 937                 err = -EINVAL;
 938                 goto errout;
 939         }
 940
 941         dev = dev_queue->dev;
 942         sch = kzalloc_node(size, GFP_KERNEL, netdev_queue_numa_node_read(dev_queue));
 943
 944         if (!sch)
 945                 goto errout;
 946         __skb_queue_head_init(&sch->gso_skb);
 947         __skb_queue_head_init(&sch->skb_bad_txq);
 948         qdisc_skb_head_init(&sch->q);
 949         gnet_stats_basic_sync_init(&sch->bstats);
 950         spin_lock_init(&sch->q.lock);
 951
 952         if (ops->static_flags & TCQ_F_CPUSTATS) {
 953                 sch->cpu_bstats =
 954                         netdev_alloc_pcpu_stats(struct gnet_stats_basic_sync);
 955                 if (!sch->cpu_bstats)
 956                         goto errout1;
 957
 958                 sch->cpu_qstats = alloc_percpu(struct gnet_stats_queue);
 959                 if (!sch->cpu_qstats) {
 960                         free_percpu(sch->cpu_bstats);
 961                         goto errout1;
 962                 }
 963         }
 964
 965         spin_lock_init(&sch->busylock);
 966         lockdep_set_class(&sch->busylock,
 967                           dev->qdisc_tx_busylock ?: &qdisc_tx_busylock);
 968
 969         /* seqlock has the same scope of busylock, for NOLOCK qdisc */
 970         spin_lock_init(&sch->seqlock);
 971         lockdep_set_class(&sch->seqlock,
 972                           dev->qdisc_tx_busylock ?: &qdisc_tx_busylock);
 973
 974         sch->ops = ops;
 975         sch->flags = ops->static_flags;
 976         sch->enqueue = ops->enqueue;
 977         sch->dequeue = ops->dequeue;
 978         sch->dev_queue = dev_queue;
 979         netdev_hold(dev, &sch->dev_tracker, GFP_KERNEL);
 980         refcount_set(&sch->refcnt, 1);
 981
 982         return sch;
 983 errout1:
 984         kfree(sch);
 985 errout:
 986         return ERR_PTR(err);
 987 }
 988
 989 struct Qdisc *qdisc_create_dflt(struct netdev_queue *dev_queue,
 990                                 const struct Qdisc_ops *ops,
 991                                 unsigned int parentid,
 992                                 struct netlink_ext_ack *extack)
 993 {
 994         struct Qdisc *sch;
 995
 996         if (!try_module_get(ops->owner)) {
 997                 NL_SET_ERR_MSG(extack, "Failed to increase module reference counter");
 998                 return NULL;
 999         }
1000
1001         sch = qdisc_alloc(dev_queue, ops, extack);
1002         if (IS_ERR(sch)) {
1003                 module_put(ops->owner);
1004                 return NULL;
1005         }
1006         sch->parent = parentid;
1007
1008         if (!ops->init || ops->init(sch, NULL, extack) == 0) {
1009                 trace_qdisc_create(ops, dev_queue->dev, parentid);
1010                 return sch;
1011         }
1012
1013         qdisc_put(sch);
1014         return NULL;
1015 }
1016 EXPORT_SYMBOL(qdisc_create_dflt);
1017
1018 /* Under qdisc_lock(qdisc) and BH! */
1019
1020 void qdisc_reset(struct Qdisc *qdisc)
1021 {
1022         const struct Qdisc_ops *ops = qdisc->ops;
1023
1024         trace_qdisc_reset(qdisc);
1025
1026         if (ops->reset)
1027                 ops->reset(qdisc);
1028
1029         __skb_queue_purge(&qdisc->gso_skb);
1030         __skb_queue_purge(&qdisc->skb_bad_txq);
1031
1032         qdisc->q.qlen = 0;
1033         qdisc->qstats.backlog = 0;
1034 }
1035 EXPORT_SYMBOL(qdisc_reset);
1036
1037 void qdisc_free(struct Qdisc *qdisc)
1038 {
1039         if (qdisc_is_percpu_stats(qdisc)) {
1040                 free_percpu(qdisc->cpu_bstats);
1041                 free_percpu(qdisc->cpu_qstats);
1042         }
1043
1044         kfree(qdisc);
1045 }
1046
1047 static void qdisc_free_cb(struct rcu_head *head)
1048 {
1049         struct Qdisc *q = container_of(head, struct Qdisc, rcu);
1050
1051         qdisc_free(q);
1052 }
1053
1054 static void qdisc_destroy(struct Qdisc *qdisc)
1055 {
1056         const struct Qdisc_ops  *ops = qdisc->ops;
1057
1058 #ifdef CONFIG_NET_SCHED
1059         qdisc_hash_del(qdisc);
1060
1061         qdisc_put_stab(rtnl_dereference(qdisc->stab));
1062 #endif
1063         gen_kill_estimator(&qdisc->rate_est);
1064
1065         qdisc_reset(qdisc);
1066
1067         if (ops->destroy)
1068                 ops->destroy(qdisc);
1069
1070         module_put(ops->owner);
1071         netdev_put(qdisc_dev(qdisc), &qdisc->dev_tracker);
1072
1073         trace_qdisc_destroy(qdisc);
1074
1075         call_rcu(&qdisc->rcu, qdisc_free_cb);
1076 }
1077
1078 void qdisc_put(struct Qdisc *qdisc)
1079 {
1080         if (!qdisc)
1081                 return;
1082
1083         if (qdisc->flags & TCQ_F_BUILTIN ||
1084             !refcount_dec_and_test(&qdisc->refcnt))
1085                 return;
1086
1087         qdisc_destroy(qdisc);
1088 }
1089 EXPORT_SYMBOL(qdisc_put);
1090
1091 /* Version of qdisc_put() that is called with rtnl mutex unlocked.
1092  * Intended to be used as optimization, this function only takes rtnl lock if
1093  * qdisc reference counter reached zero.
1094  */
1095
1096 void qdisc_put_unlocked(struct Qdisc *qdisc)
1097 {
1098         if (qdisc->flags & TCQ_F_BUILTIN ||
1099             !refcount_dec_and_rtnl_lock(&qdisc->refcnt))
1100                 return;
1101
1102         qdisc_destroy(qdisc);
1103         rtnl_unlock();
1104 }
1105 EXPORT_SYMBOL(qdisc_put_unlocked);
1106
1107 /* Attach toplevel qdisc to device queue. */
1108 struct Qdisc *dev_graft_qdisc(struct netdev_queue *dev_queue,
1109                               struct Qdisc *qdisc)
1110 {
1111         struct Qdisc *oqdisc = dev_queue->qdisc_sleeping;
1112         spinlock_t *root_lock;
1113
1114         root_lock = qdisc_lock(oqdisc);
1115         spin_lock_bh(root_lock);
1116
1117         /* ... and graft new one */
1118         if (qdisc == NULL)
1119                 qdisc = &noop_qdisc;
1120         dev_queue->qdisc_sleeping = qdisc;
1121         rcu_assign_pointer(dev_queue->qdisc, &noop_qdisc);
1122
1123         spin_unlock_bh(root_lock);
1124
1125         return oqdisc;
1126 }
1127 EXPORT_SYMBOL(dev_graft_qdisc);
1128
1129 static void attach_one_default_qdisc(struct net_device *dev,
1130                                      struct netdev_queue *dev_queue,
1131                                      void *_unused)
1132 {
1133         struct Qdisc *qdisc;
1134         const struct Qdisc_ops *ops = default_qdisc_ops;
1135
1136         if (dev->priv_flags & IFF_NO_QUEUE)
1137                 ops = &noqueue_qdisc_ops;
1138         else if(dev->type == ARPHRD_CAN)
1139                 ops = &pfifo_fast_ops;
1140
1141         qdisc = qdisc_create_dflt(dev_queue, ops, TC_H_ROOT, NULL);
1142         if (!qdisc)
1143                 return;
1144
1145         if (!netif_is_multiqueue(dev))
1146                 qdisc->flags |= TCQ_F_ONETXQUEUE | TCQ_F_NOPARENT;
1147         dev_queue->qdisc_sleeping = qdisc;
1148 }
1149
1150 static void attach_default_qdiscs(struct net_device *dev)
1151 {
1152         struct netdev_queue *txq;
1153         struct Qdisc *qdisc;
1154
1155         txq = netdev_get_tx_queue(dev, 0);
1156
1157         if (!netif_is_multiqueue(dev) ||
1158             dev->priv_flags & IFF_NO_QUEUE) {
1159                 netdev_for_each_tx_queue(dev, attach_one_default_qdisc, NULL);
1160                 qdisc = txq->qdisc_sleeping;
1161                 rcu_assign_pointer(dev->qdisc, qdisc);
1162                 qdisc_refcount_inc(qdisc);
1163         } else {
1164                 qdisc = qdisc_create_dflt(txq, &mq_qdisc_ops, TC_H_ROOT, NULL);
1165                 if (qdisc) {
1166                         rcu_assign_pointer(dev->qdisc, qdisc);
1167                         qdisc->ops->attach(qdisc);
1168                 }
1169         }
1170         qdisc = rtnl_dereference(dev->qdisc);
1171
1172         /* Detect default qdisc setup/init failed and fallback to "noqueue" */
1173         if (qdisc == &noop_qdisc) {
1174                 netdev_warn(dev, "default qdisc (%s) fail, fallback to %s\n",
1175                             default_qdisc_ops->id, noqueue_qdisc_ops.id);
1176                 dev->priv_flags |= IFF_NO_QUEUE;
1177                 netdev_for_each_tx_queue(dev, attach_one_default_qdisc, NULL);
1178                 qdisc = txq->qdisc_sleeping;
1179                 rcu_assign_pointer(dev->qdisc, qdisc);
1180                 qdisc_refcount_inc(qdisc);
1181                 dev->priv_flags ^= IFF_NO_QUEUE;
1182         }
1183
1184 #ifdef CONFIG_NET_SCHED
1185         if (qdisc != &noop_qdisc)
1186                 qdisc_hash_add(qdisc, false);
1187 #endif
1188 }
1189
1190 static void transition_one_qdisc(struct net_device *dev,
1191                                  struct netdev_queue *dev_queue,
1192                                  void *_need_watchdog)
1193 {
1194         struct Qdisc *new_qdisc = dev_queue->qdisc_sleeping;
1195         int *need_watchdog_p = _need_watchdog;
1196
1197         if (!(new_qdisc->flags & TCQ_F_BUILTIN))
1198                 clear_bit(__QDISC_STATE_DEACTIVATED, &new_qdisc->state);
1199
1200         rcu_assign_pointer(dev_queue->qdisc, new_qdisc);
1201         if (need_watchdog_p) {
1202                 WRITE_ONCE(dev_queue->trans_start, 0);
1203                 *need_watchdog_p = 1;
1204         }
1205 }
1206
1207 void dev_activate(struct net_device *dev)
1208 {
1209         int need_watchdog;
1210
1211         /* No queueing discipline is attached to device;
1212          * create default one for devices, which need queueing
1213          * and noqueue_qdisc for virtual interfaces
1214          */
1215
1216         if (rtnl_dereference(dev->qdisc) == &noop_qdisc)
1217                 attach_default_qdiscs(dev);
1218
1219         if (!netif_carrier_ok(dev))
1220                 /* Delay activation until next carrier-on event */
1221                 return;
1222
1223         need_watchdog = 0;
1224         netdev_for_each_tx_queue(dev, transition_one_qdisc, &need_watchdog);
1225         if (dev_ingress_queue(dev))
1226                 transition_one_qdisc(dev, dev_ingress_queue(dev), NULL);
1227
1228         if (need_watchdog) {
1229                 netif_trans_update(dev);
1230                 dev_watchdog_up(dev);
1231         }
1232 }
1233 EXPORT_SYMBOL(dev_activate);
1234
1235 static void qdisc_deactivate(struct Qdisc *qdisc)
1236 {
1237         if (qdisc->flags & TCQ_F_BUILTIN)
1238                 return;
1239
1240         set_bit(__QDISC_STATE_DEACTIVATED, &qdisc->state);
1241 }
1242
1243 static void dev_deactivate_queue(struct net_device *dev,
1244                                  struct netdev_queue *dev_queue,
1245                                  void *_qdisc_default)
1246 {
1247         struct Qdisc *qdisc_default = _qdisc_default;
1248         struct Qdisc *qdisc;
1249
1250         qdisc = rtnl_dereference(dev_queue->qdisc);
1251         if (qdisc) {
1252                 qdisc_deactivate(qdisc);
1253                 rcu_assign_pointer(dev_queue->qdisc, qdisc_default);
1254         }
1255 }
1256
1257 static void dev_reset_queue(struct net_device *dev,
1258                             struct netdev_queue *dev_queue,
1259                             void *_unused)
1260 {
1261         struct Qdisc *qdisc;
1262         bool nolock;
1263
1264         qdisc = dev_queue->qdisc_sleeping;
1265         if (!qdisc)
1266                 return;
1267
1268         nolock = qdisc->flags & TCQ_F_NOLOCK;
1269
1270         if (nolock)
1271                 spin_lock_bh(&qdisc->seqlock);
1272         spin_lock_bh(qdisc_lock(qdisc));
1273
1274         qdisc_reset(qdisc);
1275
1276         spin_unlock_bh(qdisc_lock(qdisc));
1277         if (nolock) {
1278                 clear_bit(__QDISC_STATE_MISSED, &qdisc->state);
1279                 clear_bit(__QDISC_STATE_DRAINING, &qdisc->state);
1280                 spin_unlock_bh(&qdisc->seqlock);
1281         }
1282 }
1283
1284 static bool some_qdisc_is_busy(struct net_device *dev)
1285 {
1286         unsigned int i;
1287
1288         for (i = 0; i < dev->num_tx_queues; i++) {
1289                 struct netdev_queue *dev_queue;
1290                 spinlock_t *root_lock;
1291                 struct Qdisc *q;
1292                 int val;
1293
1294                 dev_queue = netdev_get_tx_queue(dev, i);
1295                 q = dev_queue->qdisc_sleeping;
1296
1297                 root_lock = qdisc_lock(q);
1298                 spin_lock_bh(root_lock);
1299
1300                 val = (qdisc_is_running(q) ||
1301                        test_bit(__QDISC_STATE_SCHED, &q->state));
1302
1303                 spin_unlock_bh(root_lock);
1304
1305                 if (val)
1306                         return true;
1307         }
1308         return false;
1309 }
1310
1311 /**
1312  *      dev_deactivate_many - deactivate transmissions on several devices
1313  *      @head: list of devices to deactivate
1314  *
1315  *      This function returns only when all outstanding transmissions
1316  *      have completed, unless all devices are in dismantle phase.
1317  */
1318 void dev_deactivate_many(struct list_head *head)
1319 {
1320         struct net_device *dev;
1321
1322         list_for_each_entry(dev, head, close_list) {
1323                 netdev_for_each_tx_queue(dev, dev_deactivate_queue,
1324                                          &noop_qdisc);
1325                 if (dev_ingress_queue(dev))
1326                         dev_deactivate_queue(dev, dev_ingress_queue(dev),
1327                                              &noop_qdisc);
1328
1329                 dev_watchdog_down(dev);
1330         }
1331
1332         /* Wait for outstanding qdisc-less dev_queue_xmit calls or
1333          * outstanding qdisc enqueuing calls.
1334          * This is avoided if all devices are in dismantle phase :
1335          * Caller will call synchronize_net() for us
1336          */
1337         synchronize_net();
1338
1339         list_for_each_entry(dev, head, close_list) {
1340                 netdev_for_each_tx_queue(dev, dev_reset_queue, NULL);
1341
1342                 if (dev_ingress_queue(dev))
1343                         dev_reset_queue(dev, dev_ingress_queue(dev), NULL);
1344         }
1345
1346         /* Wait for outstanding qdisc_run calls. */
1347         list_for_each_entry(dev, head, close_list) {
1348                 while (some_qdisc_is_busy(dev)) {
1349                         /* wait_event() would avoid this sleep-loop but would
1350                          * require expensive checks in the fast paths of packet
1351                          * processing which isn't worth it.
1352                          */
1353                         schedule_timeout_uninterruptible(1);
1354                 }
1355         }
1356 }
1357
1358 void dev_deactivate(struct net_device *dev)
1359 {
1360         LIST_HEAD(single);
1361
1362         list_add(&dev->close_list, &single);
1363         dev_deactivate_many(&single);
1364         list_del(&single);
1365 }
1366 EXPORT_SYMBOL(dev_deactivate);
1367
1368 static int qdisc_change_tx_queue_len(struct net_device *dev,
1369                                      struct netdev_queue *dev_queue)
1370 {
1371         struct Qdisc *qdisc = dev_queue->qdisc_sleeping;
1372         const struct Qdisc_ops *ops = qdisc->ops;
1373
1374         if (ops->change_tx_queue_len)
1375                 return ops->change_tx_queue_len(qdisc, dev->tx_queue_len);
1376         return 0;
1377 }
1378
1379 void dev_qdisc_change_real_num_tx(struct net_device *dev,
1380                                   unsigned int new_real_tx)
1381 {
1382         struct Qdisc *qdisc = rtnl_dereference(dev->qdisc);
1383
1384         if (qdisc->ops->change_real_num_tx)
1385                 qdisc->ops->change_real_num_tx(qdisc, new_real_tx);
1386 }
1387
1388 void mq_change_real_num_tx(struct Qdisc *sch, unsigned int new_real_tx)
1389 {
1390 #ifdef CONFIG_NET_SCHED
1391         struct net_device *dev = qdisc_dev(sch);
1392         struct Qdisc *qdisc;
1393         unsigned int i;
1394
1395         for (i = new_real_tx; i < dev->real_num_tx_queues; i++) {
1396                 qdisc = netdev_get_tx_queue(dev, i)->qdisc_sleeping;
1397                 /* Only update the default qdiscs we created,
1398                  * qdiscs with handles are always hashed.
1399                  */
1400                 if (qdisc != &noop_qdisc && !qdisc->handle)
1401                         qdisc_hash_del(qdisc);
1402         }
1403         for (i = dev->real_num_tx_queues; i < new_real_tx; i++) {
1404                 qdisc = netdev_get_tx_queue(dev, i)->qdisc_sleeping;
1405                 if (qdisc != &noop_qdisc && !qdisc->handle)
1406                         qdisc_hash_add(qdisc, false);
1407         }
1408 #endif
1409 }
1410 EXPORT_SYMBOL(mq_change_real_num_tx);
1411
1412 int dev_qdisc_change_tx_queue_len(struct net_device *dev)
1413 {
1414         bool up = dev->flags & IFF_UP;
1415         unsigned int i;
1416         int ret = 0;
1417
1418         if (up)
1419                 dev_deactivate(dev);
1420
1421         for (i = 0; i < dev->num_tx_queues; i++) {
1422                 ret = qdisc_change_tx_queue_len(dev, &dev->_tx[i]);
1423
1424                 /* TODO: revert changes on a partial failure */
1425                 if (ret)
1426                         break;
1427         }
1428
1429         if (up)
1430                 dev_activate(dev);
1431         return ret;
1432 }
1433
1434 static void dev_init_scheduler_queue(struct net_device *dev,
1435                                      struct netdev_queue *dev_queue,
1436                                      void *_qdisc)
1437 {
1438         struct Qdisc *qdisc = _qdisc;
1439
1440         rcu_assign_pointer(dev_queue->qdisc, qdisc);
1441         dev_queue->qdisc_sleeping = qdisc;
1442 }
1443
1444 void dev_init_scheduler(struct net_device *dev)
1445 {
1446         rcu_assign_pointer(dev->qdisc, &noop_qdisc);
1447         netdev_for_each_tx_queue(dev, dev_init_scheduler_queue, &noop_qdisc);
1448         if (dev_ingress_queue(dev))
1449                 dev_init_scheduler_queue(dev, dev_ingress_queue(dev), &noop_qdisc);
1450
1451         timer_setup(&dev->watchdog_timer, dev_watchdog, 0);
1452 }
1453
1454 static void shutdown_scheduler_queue(struct net_device *dev,
1455                                      struct netdev_queue *dev_queue,
1456                                      void *_qdisc_default)
1457 {
1458         struct Qdisc *qdisc = dev_queue->qdisc_sleeping;
1459         struct Qdisc *qdisc_default = _qdisc_default;
1460
1461         if (qdisc) {
1462                 rcu_assign_pointer(dev_queue->qdisc, qdisc_default);
1463                 dev_queue->qdisc_sleeping = qdisc_default;
1464
1465                 qdisc_put(qdisc);
1466         }
1467 }
1468
1469 void dev_shutdown(struct net_device *dev)
1470 {
1471         netdev_for_each_tx_queue(dev, shutdown_scheduler_queue, &noop_qdisc);
1472         if (dev_ingress_queue(dev))
1473                 shutdown_scheduler_queue(dev, dev_ingress_queue(dev), &noop_qdisc);
1474         qdisc_put(rtnl_dereference(dev->qdisc));
1475         rcu_assign_pointer(dev->qdisc, &noop_qdisc);
1476
1477         WARN_ON(timer_pending(&dev->watchdog_timer));
1478 }
1479
1480 /**
1481  * psched_ratecfg_precompute__() - Pre-compute values for reciprocal division
1482  * @rate:   Rate to compute reciprocal division values of
1483  * @mult:   Multiplier for reciprocal division
1484  * @shift:  Shift for reciprocal division
1485  *
1486  * The multiplier and shift for reciprocal division by rate are stored
1487  * in mult and shift.
1488  *
1489  * The deal here is to replace a divide by a reciprocal one
1490  * in fast path (a reciprocal divide is a multiply and a shift)
1491  *
1492  * Normal formula would be :
1493  *  time_in_ns = (NSEC_PER_SEC * len) / rate_bps
1494  *
1495  * We compute mult/shift to use instead :
1496  *  time_in_ns = (len * mult) >> shift;
1497  *
1498  * We try to get the highest possible mult value for accuracy,
1499  * but have to make sure no overflows will ever happen.
1500  *
1501  * reciprocal_value() is not used here it doesn't handle 64-bit values.
1502  */
1503 static void psched_ratecfg_precompute__(u64 rate, u32 *mult, u8 *shift)
1504 {
1505         u64 factor = NSEC_PER_SEC;
1506
1507         *mult = 1;
1508         *shift = 0;
1509
1510         if (rate <= 0)
1511                 return;
1512
1513         for (;;) {
1514                 *mult = div64_u64(factor, rate);
1515                 if (*mult & (1U << 31) || factor & (1ULL << 63))
1516                         break;
1517                 factor <<= 1;
1518                 (*shift)++;
1519         }
1520 }
1521
1522 void psched_ratecfg_precompute(struct psched_ratecfg *r,
1523                                const struct tc_ratespec *conf,
1524                                u64 rate64)
1525 {
1526         memset(r, 0, sizeof(*r));
1527         r->overhead = conf->overhead;
1528         r->mpu = conf->mpu;
1529         r->rate_bytes_ps = max_t(u64, conf->rate, rate64);
1530         r->linklayer = (conf->linklayer & TC_LINKLAYER_MASK);
1531         psched_ratecfg_precompute__(r->rate_bytes_ps, &r->mult, &r->shift);
1532 }
1533 EXPORT_SYMBOL(psched_ratecfg_precompute);
1534
1535 void psched_ppscfg_precompute(struct psched_pktrate *r, u64 pktrate64)
1536 {
1537         r->rate_pkts_ps = pktrate64;
1538         psched_ratecfg_precompute__(r->rate_pkts_ps, &r->mult, &r->shift);
1539 }
1540 EXPORT_SYMBOL(psched_ppscfg_precompute);
1541
1542 void mini_qdisc_pair_swap(struct mini_Qdisc_pair *miniqp,
1543                           struct tcf_proto *tp_head)
1544 {
1545         /* Protected with chain0->filter_chain_lock.
1546          * Can't access chain directly because tp_head can be NULL.
1547          */
1548         struct mini_Qdisc *miniq_old =
1549                 rcu_dereference_protected(*miniqp->p_miniq, 1);
1550         struct mini_Qdisc *miniq;
1551
1552         if (!tp_head) {
1553                 RCU_INIT_POINTER(*miniqp->p_miniq, NULL);
1554         } else {
1555                 miniq = miniq_old != &miniqp->miniq1 ?
1556                         &miniqp->miniq1 : &miniqp->miniq2;
1557
1558                 /* We need to make sure that readers won't see the miniq
1559                  * we are about to modify. So ensure that at least one RCU
1560                  * grace period has elapsed since the miniq was made
1561                  * inactive.
1562                  */
1563                 if (IS_ENABLED(CONFIG_PREEMPT_RT))
1564                         cond_synchronize_rcu(miniq->rcu_state);
1565                 else if (!poll_state_synchronize_rcu(miniq->rcu_state))
1566                         synchronize_rcu_expedited();
1567
1568                 miniq->filter_list = tp_head;
1569                 rcu_assign_pointer(*miniqp->p_miniq, miniq);
1570         }
1571
1572         if (miniq_old)
1573                 /* This is counterpart of the rcu sync above. We need to
1574                  * block potential new user of miniq_old until all readers
1575                  * are not seeing it.
1576                  */
1577                 miniq_old->rcu_state = start_poll_synchronize_rcu();
1578 }
1579 EXPORT_SYMBOL(mini_qdisc_pair_swap);
1580
1581 void mini_qdisc_pair_block_init(struct mini_Qdisc_pair *miniqp,
1582                                 struct tcf_block *block)
1583 {
1584         miniqp->miniq1.block = block;
1585         miniqp->miniq2.block = block;
1586 }
1587 EXPORT_SYMBOL(mini_qdisc_pair_block_init);
1588
1589 void mini_qdisc_pair_init(struct mini_Qdisc_pair *miniqp, struct Qdisc *qdisc,
1590                           struct mini_Qdisc __rcu **p_miniq)
1591 {
1592         miniqp->miniq1.cpu_bstats = qdisc->cpu_bstats;
1593         miniqp->miniq1.cpu_qstats = qdisc->cpu_qstats;
1594         miniqp->miniq2.cpu_bstats = qdisc->cpu_bstats;
1595         miniqp->miniq2.cpu_qstats = qdisc->cpu_qstats;
1596         miniqp->miniq1.rcu_state = get_state_synchronize_rcu();
1597         miniqp->miniq2.rcu_state = miniqp->miniq1.rcu_state;
1598         miniqp->p_miniq = p_miniq;
1599 }
1600 EXPORT_SYMBOL(mini_qdisc_pair_init);