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 = READ_ONCE(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 res = READ_ONCE(netdev_get_tx_queue(dev, 0)->trans_start);
 431         unsigned long val;
 432         unsigned int i;
 433
 434         for (i = 1; i < dev->num_tx_queues; i++) {
 435                 val = READ_ONCE(netdev_get_tx_queue(dev, i)->trans_start);
 436                 if (val && time_after(val, res))
 437                         res = val;
 438         }
 439
 440         return res;
 441 }
 442 EXPORT_SYMBOL(dev_trans_start);
 443
 444 static void netif_freeze_queues(struct net_device *dev)
 445 {
 446         unsigned int i;
 447         int cpu;
 448
 449         cpu = smp_processor_id();
 450         for (i = 0; i < dev->num_tx_queues; i++) {
 451                 struct netdev_queue *txq = netdev_get_tx_queue(dev, i);
 452
 453                 /* We are the only thread of execution doing a
 454                  * freeze, but we have to grab the _xmit_lock in
 455                  * order to synchronize with threads which are in
 456                  * the ->hard_start_xmit() handler and already
 457                  * checked the frozen bit.
 458                  */
 459                 __netif_tx_lock(txq, cpu);
 460                 set_bit(__QUEUE_STATE_FROZEN, &txq->state);
 461                 __netif_tx_unlock(txq);
 462         }
 463 }
 464
 465 void netif_tx_lock(struct net_device *dev)
 466 {
 467         spin_lock(&dev->tx_global_lock);
 468         netif_freeze_queues(dev);
 469 }
 470 EXPORT_SYMBOL(netif_tx_lock);
 471
 472 static void netif_unfreeze_queues(struct net_device *dev)
 473 {
 474         unsigned int i;
 475
 476         for (i = 0; i < dev->num_tx_queues; i++) {
 477                 struct netdev_queue *txq = netdev_get_tx_queue(dev, i);
 478
 479                 /* No need to grab the _xmit_lock here.  If the
 480                  * queue is not stopped for another reason, we
 481                  * force a schedule.
 482                  */
 483                 clear_bit(__QUEUE_STATE_FROZEN, &txq->state);
 484                 netif_schedule_queue(txq);
 485         }
 486 }
 487
 488 void netif_tx_unlock(struct net_device *dev)
 489 {
 490         netif_unfreeze_queues(dev);
 491         spin_unlock(&dev->tx_global_lock);
 492 }
 493 EXPORT_SYMBOL(netif_tx_unlock);
 494
 495 static void dev_watchdog(struct timer_list *t)
 496 {
 497         struct net_device *dev = from_timer(dev, t, watchdog_timer);
 498         bool release = true;
 499
 500         spin_lock(&dev->tx_global_lock);
 501         if (!qdisc_tx_is_noop(dev)) {
 502                 if (netif_device_present(dev) &&
 503                     netif_running(dev) &&
 504                     netif_carrier_ok(dev)) {
 505                         int some_queue_timedout = 0;
 506                         unsigned int i;
 507                         unsigned long trans_start;
 508
 509                         for (i = 0; i < dev->num_tx_queues; i++) {
 510                                 struct netdev_queue *txq;
 511
 512                                 txq = netdev_get_tx_queue(dev, i);
 513                                 trans_start = READ_ONCE(txq->trans_start);
 514                                 if (netif_xmit_stopped(txq) &&
 515                                     time_after(jiffies, (trans_start +
 516                                                          dev->watchdog_timeo))) {
 517                                         some_queue_timedout = 1;
 518                                         atomic_long_inc(&txq->trans_timeout);
 519                                         break;
 520                                 }
 521                         }
 522
 523                         if (unlikely(some_queue_timedout)) {
 524                                 trace_net_dev_xmit_timeout(dev, i);
 525                                 WARN_ONCE(1, KERN_INFO "NETDEV WATCHDOG: %s (%s): transmit queue %u timed out\n",
 526                                        dev->name, netdev_drivername(dev), i);
 527                                 netif_freeze_queues(dev);
 528                                 dev->netdev_ops->ndo_tx_timeout(dev, i);
 529                                 netif_unfreeze_queues(dev);
 530                         }
 531                         if (!mod_timer(&dev->watchdog_timer,
 532                                        round_jiffies(jiffies +
 533                                                      dev->watchdog_timeo)))
 534                                 release = false;
 535                 }
 536         }
 537         spin_unlock(&dev->tx_global_lock);
 538
 539         if (release)
 540                 netdev_put(dev, &dev->watchdog_dev_tracker);
 541 }
 542
 543 void __netdev_watchdog_up(struct net_device *dev)
 544 {
 545         if (dev->netdev_ops->ndo_tx_timeout) {
 546                 if (dev->watchdog_timeo <= 0)
 547                         dev->watchdog_timeo = 5*HZ;
 548                 if (!mod_timer(&dev->watchdog_timer,
 549                                round_jiffies(jiffies + dev->watchdog_timeo)))
 550                         netdev_hold(dev, &dev->watchdog_dev_tracker,
 551                                     GFP_ATOMIC);
 552         }
 553 }
 554 EXPORT_SYMBOL_GPL(__netdev_watchdog_up);
 555
 556 static void dev_watchdog_up(struct net_device *dev)
 557 {
 558         __netdev_watchdog_up(dev);
 559 }
 560
 561 static void dev_watchdog_down(struct net_device *dev)
 562 {
 563         netif_tx_lock_bh(dev);
 564         if (del_timer(&dev->watchdog_timer))
 565                 netdev_put(dev, &dev->watchdog_dev_tracker);
 566         netif_tx_unlock_bh(dev);
 567 }
 568
 569 /**
 570  *      netif_carrier_on - set carrier
 571  *      @dev: network device
 572  *
 573  * Device has detected acquisition of carrier.
 574  */
 575 void netif_carrier_on(struct net_device *dev)
 576 {
 577         if (test_and_clear_bit(__LINK_STATE_NOCARRIER, &dev->state)) {
 578                 if (dev->reg_state == NETREG_UNINITIALIZED)
 579                         return;
 580                 atomic_inc(&dev->carrier_up_count);
 581                 linkwatch_fire_event(dev);
 582                 if (netif_running(dev))
 583                         __netdev_watchdog_up(dev);
 584         }
 585 }
 586 EXPORT_SYMBOL(netif_carrier_on);
 587
 588 /**
 589  *      netif_carrier_off - clear carrier
 590  *      @dev: network device
 591  *
 592  * Device has detected loss of carrier.
 593  */
 594 void netif_carrier_off(struct net_device *dev)
 595 {
 596         if (!test_and_set_bit(__LINK_STATE_NOCARRIER, &dev->state)) {
 597                 if (dev->reg_state == NETREG_UNINITIALIZED)
 598                         return;
 599                 atomic_inc(&dev->carrier_down_count);
 600                 linkwatch_fire_event(dev);
 601         }
 602 }
 603 EXPORT_SYMBOL(netif_carrier_off);
 604
 605 /**
 606  *      netif_carrier_event - report carrier state event
 607  *      @dev: network device
 608  *
 609  * Device has detected a carrier event but the carrier state wasn't changed.
 610  * Use in drivers when querying carrier state asynchronously, to avoid missing
 611  * events (link flaps) if link recovers before it's queried.
 612  */
 613 void netif_carrier_event(struct net_device *dev)
 614 {
 615         if (dev->reg_state == NETREG_UNINITIALIZED)
 616                 return;
 617         atomic_inc(&dev->carrier_up_count);
 618         atomic_inc(&dev->carrier_down_count);
 619         linkwatch_fire_event(dev);
 620 }
 621 EXPORT_SYMBOL_GPL(netif_carrier_event);
 622
 623 /* "NOOP" scheduler: the best scheduler, recommended for all interfaces
 624    under all circumstances. It is difficult to invent anything faster or
 625    cheaper.
 626  */
 627
 628 static int noop_enqueue(struct sk_buff *skb, struct Qdisc *qdisc,
 629                         struct sk_buff **to_free)
 630 {
 631         __qdisc_drop(skb, to_free);
 632         return NET_XMIT_CN;
 633 }
 634
 635 static struct sk_buff *noop_dequeue(struct Qdisc *qdisc)
 636 {
 637         return NULL;
 638 }
 639
 640 struct Qdisc_ops noop_qdisc_ops __read_mostly = {
 641         .id             =       "noop",
 642         .priv_size      =       0,
 643         .enqueue        =       noop_enqueue,
 644         .dequeue        =       noop_dequeue,
 645         .peek           =       noop_dequeue,
 646         .owner          =       THIS_MODULE,
 647 };
 648
 649 static struct netdev_queue noop_netdev_queue = {
 650         RCU_POINTER_INITIALIZER(qdisc, &noop_qdisc),
 651         .qdisc_sleeping =       &noop_qdisc,
 652 };
 653
 654 struct Qdisc noop_qdisc = {
 655         .enqueue        =       noop_enqueue,
 656         .dequeue        =       noop_dequeue,
 657         .flags          =       TCQ_F_BUILTIN,
 658         .ops            =       &noop_qdisc_ops,
 659         .q.lock         =       __SPIN_LOCK_UNLOCKED(noop_qdisc.q.lock),
 660         .dev_queue      =       &noop_netdev_queue,
 661         .busylock       =       __SPIN_LOCK_UNLOCKED(noop_qdisc.busylock),
 662         .gso_skb = {
 663                 .next = (struct sk_buff *)&noop_qdisc.gso_skb,
 664                 .prev = (struct sk_buff *)&noop_qdisc.gso_skb,
 665                 .qlen = 0,
 666                 .lock = __SPIN_LOCK_UNLOCKED(noop_qdisc.gso_skb.lock),
 667         },
 668         .skb_bad_txq = {
 669                 .next = (struct sk_buff *)&noop_qdisc.skb_bad_txq,
 670                 .prev = (struct sk_buff *)&noop_qdisc.skb_bad_txq,
 671                 .qlen = 0,
 672                 .lock = __SPIN_LOCK_UNLOCKED(noop_qdisc.skb_bad_txq.lock),
 673         },
 674 };
 675 EXPORT_SYMBOL(noop_qdisc);
 676
 677 static int noqueue_init(struct Qdisc *qdisc, struct nlattr *opt,
 678                         struct netlink_ext_ack *extack)
 679 {
 680         /* register_qdisc() assigns a default of noop_enqueue if unset,
 681          * but __dev_queue_xmit() treats noqueue only as such
 682          * if this is NULL - so clear it here. */
 683         qdisc->enqueue = NULL;
 684         return 0;
 685 }
 686
 687 struct Qdisc_ops noqueue_qdisc_ops __read_mostly = {
 688         .id             =       "noqueue",
 689         .priv_size      =       0,
 690         .init           =       noqueue_init,
 691         .enqueue        =       noop_enqueue,
 692         .dequeue        =       noop_dequeue,
 693         .peek           =       noop_dequeue,
 694         .owner          =       THIS_MODULE,
 695 };
 696
 697 static const u8 prio2band[TC_PRIO_MAX + 1] = {
 698         1, 2, 2, 2, 1, 2, 0, 0 , 1, 1, 1, 1, 1, 1, 1, 1
 699 };
 700
 701 /* 3-band FIFO queue: old style, but should be a bit faster than
 702    generic prio+fifo combination.
 703  */
 704
 705 #define PFIFO_FAST_BANDS 3
 706
 707 /*
 708  * Private data for a pfifo_fast scheduler containing:
 709  *      - rings for priority bands
 710  */
 711 struct pfifo_fast_priv {
 712         struct skb_array q[PFIFO_FAST_BANDS];
 713 };
 714
 715 static inline struct skb_array *band2list(struct pfifo_fast_priv *priv,
 716                                           int band)
 717 {
 718         return &priv->q[band];
 719 }
 720
 721 static int pfifo_fast_enqueue(struct sk_buff *skb, struct Qdisc *qdisc,
 722                               struct sk_buff **to_free)
 723 {
 724         int band = prio2band[skb->priority & TC_PRIO_MAX];
 725         struct pfifo_fast_priv *priv = qdisc_priv(qdisc);
 726         struct skb_array *q = band2list(priv, band);
 727         unsigned int pkt_len = qdisc_pkt_len(skb);
 728         int err;
 729
 730         err = skb_array_produce(q, skb);
 731
 732         if (unlikely(err)) {
 733                 if (qdisc_is_percpu_stats(qdisc))
 734                         return qdisc_drop_cpu(skb, qdisc, to_free);
 735                 else
 736                         return qdisc_drop(skb, qdisc, to_free);
 737         }
 738
 739         qdisc_update_stats_at_enqueue(qdisc, pkt_len);
 740         return NET_XMIT_SUCCESS;
 741 }
 742
 743 static struct sk_buff *pfifo_fast_dequeue(struct Qdisc *qdisc)
 744 {
 745         struct pfifo_fast_priv *priv = qdisc_priv(qdisc);
 746         struct sk_buff *skb = NULL;
 747         bool need_retry = true;
 748         int band;
 749
 750 retry:
 751         for (band = 0; band < PFIFO_FAST_BANDS && !skb; band++) {
 752                 struct skb_array *q = band2list(priv, band);
 753
 754                 if (__skb_array_empty(q))
 755                         continue;
 756
 757                 skb = __skb_array_consume(q);
 758         }
 759         if (likely(skb)) {
 760                 qdisc_update_stats_at_dequeue(qdisc, skb);
 761         } else if (need_retry &&
 762                    READ_ONCE(qdisc->state) & QDISC_STATE_NON_EMPTY) {
 763                 /* Delay clearing the STATE_MISSED here to reduce
 764                  * the overhead of the second spin_trylock() in
 765                  * qdisc_run_begin() and __netif_schedule() calling
 766                  * in qdisc_run_end().
 767                  */
 768                 clear_bit(__QDISC_STATE_MISSED, &qdisc->state);
 769                 clear_bit(__QDISC_STATE_DRAINING, &qdisc->state);
 770
 771                 /* Make sure dequeuing happens after clearing
 772                  * STATE_MISSED.
 773                  */
 774                 smp_mb__after_atomic();
 775
 776                 need_retry = false;
 777
 778                 goto retry;
 779         }
 780
 781         return skb;
 782 }
 783
 784 static struct sk_buff *pfifo_fast_peek(struct Qdisc *qdisc)
 785 {
 786         struct pfifo_fast_priv *priv = qdisc_priv(qdisc);
 787         struct sk_buff *skb = NULL;
 788         int band;
 789
 790         for (band = 0; band < PFIFO_FAST_BANDS && !skb; band++) {
 791                 struct skb_array *q = band2list(priv, band);
 792
 793                 skb = __skb_array_peek(q);
 794         }
 795
 796         return skb;
 797 }
 798
 799 static void pfifo_fast_reset(struct Qdisc *qdisc)
 800 {
 801         int i, band;
 802         struct pfifo_fast_priv *priv = qdisc_priv(qdisc);
 803
 804         for (band = 0; band < PFIFO_FAST_BANDS; band++) {
 805                 struct skb_array *q = band2list(priv, band);
 806                 struct sk_buff *skb;
 807
 808                 /* NULL ring is possible if destroy path is due to a failed
 809                  * skb_array_init() in pfifo_fast_init() case.
 810                  */
 811                 if (!q->ring.queue)
 812                         continue;
 813
 814                 while ((skb = __skb_array_consume(q)) != NULL)
 815                         kfree_skb(skb);
 816         }
 817
 818         if (qdisc_is_percpu_stats(qdisc)) {
 819                 for_each_possible_cpu(i) {
 820                         struct gnet_stats_queue *q;
 821
 822                         q = per_cpu_ptr(qdisc->cpu_qstats, i);
 823                         q->backlog = 0;
 824                         q->qlen = 0;
 825                 }
 826         }
 827 }
 828
 829 static int pfifo_fast_dump(struct Qdisc *qdisc, struct sk_buff *skb)
 830 {
 831         struct tc_prio_qopt opt = { .bands = PFIFO_FAST_BANDS };
 832
 833         memcpy(&opt.priomap, prio2band, TC_PRIO_MAX + 1);
 834         if (nla_put(skb, TCA_OPTIONS, sizeof(opt), &opt))
 835                 goto nla_put_failure;
 836         return skb->len;
 837
 838 nla_put_failure:
 839         return -1;
 840 }
 841
 842 static int pfifo_fast_init(struct Qdisc *qdisc, struct nlattr *opt,
 843                            struct netlink_ext_ack *extack)
 844 {
 845         unsigned int qlen = qdisc_dev(qdisc)->tx_queue_len;
 846         struct pfifo_fast_priv *priv = qdisc_priv(qdisc);
 847         int prio;
 848
 849         /* guard against zero length rings */
 850         if (!qlen)
 851                 return -EINVAL;
 852
 853         for (prio = 0; prio < PFIFO_FAST_BANDS; prio++) {
 854                 struct skb_array *q = band2list(priv, prio);
 855                 int err;
 856
 857                 err = skb_array_init(q, qlen, GFP_KERNEL);
 858                 if (err)
 859                         return -ENOMEM;
 860         }
 861
 862         /* Can by-pass the queue discipline */
 863         qdisc->flags |= TCQ_F_CAN_BYPASS;
 864         return 0;
 865 }
 866
 867 static void pfifo_fast_destroy(struct Qdisc *sch)
 868 {
 869         struct pfifo_fast_priv *priv = qdisc_priv(sch);
 870         int prio;
 871
 872         for (prio = 0; prio < PFIFO_FAST_BANDS; prio++) {
 873                 struct skb_array *q = band2list(priv, prio);
 874
 875                 /* NULL ring is possible if destroy path is due to a failed
 876                  * skb_array_init() in pfifo_fast_init() case.
 877                  */
 878                 if (!q->ring.queue)
 879                         continue;
 880                 /* Destroy ring but no need to kfree_skb because a call to
 881                  * pfifo_fast_reset() has already done that work.
 882                  */
 883                 ptr_ring_cleanup(&q->ring, NULL);
 884         }
 885 }
 886
 887 static int pfifo_fast_change_tx_queue_len(struct Qdisc *sch,
 888                                           unsigned int new_len)
 889 {
 890         struct pfifo_fast_priv *priv = qdisc_priv(sch);
 891         struct skb_array *bands[PFIFO_FAST_BANDS];
 892         int prio;
 893
 894         for (prio = 0; prio < PFIFO_FAST_BANDS; prio++) {
 895                 struct skb_array *q = band2list(priv, prio);
 896
 897                 bands[prio] = q;
 898         }
 899
 900         return skb_array_resize_multiple(bands, PFIFO_FAST_BANDS, new_len,
 901                                          GFP_KERNEL);
 902 }
 903
 904 struct Qdisc_ops pfifo_fast_ops __read_mostly = {
 905         .id             =       "pfifo_fast",
 906         .priv_size      =       sizeof(struct pfifo_fast_priv),
 907         .enqueue        =       pfifo_fast_enqueue,
 908         .dequeue        =       pfifo_fast_dequeue,
 909         .peek           =       pfifo_fast_peek,
 910         .init           =       pfifo_fast_init,
 911         .destroy        =       pfifo_fast_destroy,
 912         .reset          =       pfifo_fast_reset,
 913         .dump           =       pfifo_fast_dump,
 914         .change_tx_queue_len =  pfifo_fast_change_tx_queue_len,
 915         .owner          =       THIS_MODULE,
 916         .static_flags   =       TCQ_F_NOLOCK | TCQ_F_CPUSTATS,
 917 };
 918 EXPORT_SYMBOL(pfifo_fast_ops);
 919
 920 static struct lock_class_key qdisc_tx_busylock;
 921
 922 struct Qdisc *qdisc_alloc(struct netdev_queue *dev_queue,
 923                           const struct Qdisc_ops *ops,
 924                           struct netlink_ext_ack *extack)
 925 {
 926         struct Qdisc *sch;
 927         unsigned int size = sizeof(*sch) + ops->priv_size;
 928         int err = -ENOBUFS;
 929         struct net_device *dev;
 930
 931         if (!dev_queue) {
 932                 NL_SET_ERR_MSG(extack, "No device queue given");
 933                 err = -EINVAL;
 934                 goto errout;
 935         }
 936
 937         dev = dev_queue->dev;
 938         sch = kzalloc_node(size, GFP_KERNEL, netdev_queue_numa_node_read(dev_queue));
 939
 940         if (!sch)
 941                 goto errout;
 942         __skb_queue_head_init(&sch->gso_skb);
 943         __skb_queue_head_init(&sch->skb_bad_txq);
 944         gnet_stats_basic_sync_init(&sch->bstats);
 945         spin_lock_init(&sch->q.lock);
 946
 947         if (ops->static_flags & TCQ_F_CPUSTATS) {
 948                 sch->cpu_bstats =
 949                         netdev_alloc_pcpu_stats(struct gnet_stats_basic_sync);
 950                 if (!sch->cpu_bstats)
 951                         goto errout1;
 952
 953                 sch->cpu_qstats = alloc_percpu(struct gnet_stats_queue);
 954                 if (!sch->cpu_qstats) {
 955                         free_percpu(sch->cpu_bstats);
 956                         goto errout1;
 957                 }
 958         }
 959
 960         spin_lock_init(&sch->busylock);
 961         lockdep_set_class(&sch->busylock,
 962                           dev->qdisc_tx_busylock ?: &qdisc_tx_busylock);
 963
 964         /* seqlock has the same scope of busylock, for NOLOCK qdisc */
 965         spin_lock_init(&sch->seqlock);
 966         lockdep_set_class(&sch->seqlock,
 967                           dev->qdisc_tx_busylock ?: &qdisc_tx_busylock);
 968
 969         sch->ops = ops;
 970         sch->flags = ops->static_flags;
 971         sch->enqueue = ops->enqueue;
 972         sch->dequeue = ops->dequeue;
 973         sch->dev_queue = dev_queue;
 974         netdev_hold(dev, &sch->dev_tracker, GFP_KERNEL);
 975         refcount_set(&sch->refcnt, 1);
 976
 977         return sch;
 978 errout1:
 979         kfree(sch);
 980 errout:
 981         return ERR_PTR(err);
 982 }
 983
 984 struct Qdisc *qdisc_create_dflt(struct netdev_queue *dev_queue,
 985                                 const struct Qdisc_ops *ops,
 986                                 unsigned int parentid,
 987                                 struct netlink_ext_ack *extack)
 988 {
 989         struct Qdisc *sch;
 990
 991         if (!try_module_get(ops->owner)) {
 992                 NL_SET_ERR_MSG(extack, "Failed to increase module reference counter");
 993                 return NULL;
 994         }
 995
 996         sch = qdisc_alloc(dev_queue, ops, extack);
 997         if (IS_ERR(sch)) {
 998                 module_put(ops->owner);
 999                 return NULL;
1000         }
1001         sch->parent = parentid;
1002
1003         if (!ops->init || ops->init(sch, NULL, extack) == 0) {
1004                 trace_qdisc_create(ops, dev_queue->dev, parentid);
1005                 return sch;
1006         }
1007
1008         qdisc_put(sch);
1009         return NULL;
1010 }
1011 EXPORT_SYMBOL(qdisc_create_dflt);
1012
1013 /* Under qdisc_lock(qdisc) and BH! */
1014
1015 void qdisc_reset(struct Qdisc *qdisc)
1016 {
1017         const struct Qdisc_ops *ops = qdisc->ops;
1018
1019         trace_qdisc_reset(qdisc);
1020
1021         if (ops->reset)
1022                 ops->reset(qdisc);
1023
1024         __skb_queue_purge(&qdisc->gso_skb);
1025         __skb_queue_purge(&qdisc->skb_bad_txq);
1026
1027         qdisc->q.qlen = 0;
1028         qdisc->qstats.backlog = 0;
1029 }
1030 EXPORT_SYMBOL(qdisc_reset);
1031
1032 void qdisc_free(struct Qdisc *qdisc)
1033 {
1034         if (qdisc_is_percpu_stats(qdisc)) {
1035                 free_percpu(qdisc->cpu_bstats);
1036                 free_percpu(qdisc->cpu_qstats);
1037         }
1038
1039         kfree(qdisc);
1040 }
1041
1042 static void qdisc_free_cb(struct rcu_head *head)
1043 {
1044         struct Qdisc *q = container_of(head, struct Qdisc, rcu);
1045
1046         qdisc_free(q);
1047 }
1048
1049 static void qdisc_destroy(struct Qdisc *qdisc)
1050 {
1051         const struct Qdisc_ops  *ops = qdisc->ops;
1052
1053 #ifdef CONFIG_NET_SCHED
1054         qdisc_hash_del(qdisc);
1055
1056         qdisc_put_stab(rtnl_dereference(qdisc->stab));
1057 #endif
1058         gen_kill_estimator(&qdisc->rate_est);
1059
1060         qdisc_reset(qdisc);
1061
1062         if (ops->destroy)
1063                 ops->destroy(qdisc);
1064
1065         module_put(ops->owner);
1066         netdev_put(qdisc_dev(qdisc), &qdisc->dev_tracker);
1067
1068         trace_qdisc_destroy(qdisc);
1069
1070         call_rcu(&qdisc->rcu, qdisc_free_cb);
1071 }
1072
1073 void qdisc_put(struct Qdisc *qdisc)
1074 {
1075         if (!qdisc)
1076                 return;
1077
1078         if (qdisc->flags & TCQ_F_BUILTIN ||
1079             !refcount_dec_and_test(&qdisc->refcnt))
1080                 return;
1081
1082         qdisc_destroy(qdisc);
1083 }
1084 EXPORT_SYMBOL(qdisc_put);
1085
1086 /* Version of qdisc_put() that is called with rtnl mutex unlocked.
1087  * Intended to be used as optimization, this function only takes rtnl lock if
1088  * qdisc reference counter reached zero.
1089  */
1090
1091 void qdisc_put_unlocked(struct Qdisc *qdisc)
1092 {
1093         if (qdisc->flags & TCQ_F_BUILTIN ||
1094             !refcount_dec_and_rtnl_lock(&qdisc->refcnt))
1095                 return;
1096
1097         qdisc_destroy(qdisc);
1098         rtnl_unlock();
1099 }
1100 EXPORT_SYMBOL(qdisc_put_unlocked);
1101
1102 /* Attach toplevel qdisc to device queue. */
1103 struct Qdisc *dev_graft_qdisc(struct netdev_queue *dev_queue,
1104                               struct Qdisc *qdisc)
1105 {
1106         struct Qdisc *oqdisc = dev_queue->qdisc_sleeping;
1107         spinlock_t *root_lock;
1108
1109         root_lock = qdisc_lock(oqdisc);
1110         spin_lock_bh(root_lock);
1111
1112         /* ... and graft new one */
1113         if (qdisc == NULL)
1114                 qdisc = &noop_qdisc;
1115         dev_queue->qdisc_sleeping = qdisc;
1116         rcu_assign_pointer(dev_queue->qdisc, &noop_qdisc);
1117
1118         spin_unlock_bh(root_lock);
1119
1120         return oqdisc;
1121 }
1122 EXPORT_SYMBOL(dev_graft_qdisc);
1123
1124 static void shutdown_scheduler_queue(struct net_device *dev,
1125                                      struct netdev_queue *dev_queue,
1126                                      void *_qdisc_default)
1127 {
1128         struct Qdisc *qdisc = dev_queue->qdisc_sleeping;
1129         struct Qdisc *qdisc_default = _qdisc_default;
1130
1131         if (qdisc) {
1132                 rcu_assign_pointer(dev_queue->qdisc, qdisc_default);
1133                 dev_queue->qdisc_sleeping = qdisc_default;
1134
1135                 qdisc_put(qdisc);
1136         }
1137 }
1138
1139 static void attach_one_default_qdisc(struct net_device *dev,
1140                                      struct netdev_queue *dev_queue,
1141                                      void *_unused)
1142 {
1143         struct Qdisc *qdisc;
1144         const struct Qdisc_ops *ops = default_qdisc_ops;
1145
1146         if (dev->priv_flags & IFF_NO_QUEUE)
1147                 ops = &noqueue_qdisc_ops;
1148         else if(dev->type == ARPHRD_CAN)
1149                 ops = &pfifo_fast_ops;
1150
1151         qdisc = qdisc_create_dflt(dev_queue, ops, TC_H_ROOT, NULL);
1152         if (!qdisc)
1153                 return;
1154
1155         if (!netif_is_multiqueue(dev))
1156                 qdisc->flags |= TCQ_F_ONETXQUEUE | TCQ_F_NOPARENT;
1157         dev_queue->qdisc_sleeping = qdisc;
1158 }
1159
1160 static void attach_default_qdiscs(struct net_device *dev)
1161 {
1162         struct netdev_queue *txq;
1163         struct Qdisc *qdisc;
1164
1165         txq = netdev_get_tx_queue(dev, 0);
1166
1167         if (!netif_is_multiqueue(dev) ||
1168             dev->priv_flags & IFF_NO_QUEUE) {
1169                 netdev_for_each_tx_queue(dev, attach_one_default_qdisc, NULL);
1170                 qdisc = txq->qdisc_sleeping;
1171                 rcu_assign_pointer(dev->qdisc, qdisc);
1172                 qdisc_refcount_inc(qdisc);
1173         } else {
1174                 qdisc = qdisc_create_dflt(txq, &mq_qdisc_ops, TC_H_ROOT, NULL);
1175                 if (qdisc) {
1176                         rcu_assign_pointer(dev->qdisc, qdisc);
1177                         qdisc->ops->attach(qdisc);
1178                 }
1179         }
1180         qdisc = rtnl_dereference(dev->qdisc);
1181
1182         /* Detect default qdisc setup/init failed and fallback to "noqueue" */
1183         if (qdisc == &noop_qdisc) {
1184                 netdev_warn(dev, "default qdisc (%s) fail, fallback to %s\n",
1185                             default_qdisc_ops->id, noqueue_qdisc_ops.id);
1186                 netdev_for_each_tx_queue(dev, shutdown_scheduler_queue, &noop_qdisc);
1187                 dev->priv_flags |= IFF_NO_QUEUE;
1188                 netdev_for_each_tx_queue(dev, attach_one_default_qdisc, NULL);
1189                 qdisc = txq->qdisc_sleeping;
1190                 rcu_assign_pointer(dev->qdisc, qdisc);
1191                 qdisc_refcount_inc(qdisc);
1192                 dev->priv_flags ^= IFF_NO_QUEUE;
1193         }
1194
1195 #ifdef CONFIG_NET_SCHED
1196         if (qdisc != &noop_qdisc)
1197                 qdisc_hash_add(qdisc, false);
1198 #endif
1199 }
1200
1201 static void transition_one_qdisc(struct net_device *dev,
1202                                  struct netdev_queue *dev_queue,
1203                                  void *_need_watchdog)
1204 {
1205         struct Qdisc *new_qdisc = dev_queue->qdisc_sleeping;
1206         int *need_watchdog_p = _need_watchdog;
1207
1208         if (!(new_qdisc->flags & TCQ_F_BUILTIN))
1209                 clear_bit(__QDISC_STATE_DEACTIVATED, &new_qdisc->state);
1210
1211         rcu_assign_pointer(dev_queue->qdisc, new_qdisc);
1212         if (need_watchdog_p) {
1213                 WRITE_ONCE(dev_queue->trans_start, 0);
1214                 *need_watchdog_p = 1;
1215         }
1216 }
1217
1218 void dev_activate(struct net_device *dev)
1219 {
1220         int need_watchdog;
1221
1222         /* No queueing discipline is attached to device;
1223          * create default one for devices, which need queueing
1224          * and noqueue_qdisc for virtual interfaces
1225          */
1226
1227         if (rtnl_dereference(dev->qdisc) == &noop_qdisc)
1228                 attach_default_qdiscs(dev);
1229
1230         if (!netif_carrier_ok(dev))
1231                 /* Delay activation until next carrier-on event */
1232                 return;
1233
1234         need_watchdog = 0;
1235         netdev_for_each_tx_queue(dev, transition_one_qdisc, &need_watchdog);
1236         if (dev_ingress_queue(dev))
1237                 transition_one_qdisc(dev, dev_ingress_queue(dev), NULL);
1238
1239         if (need_watchdog) {
1240                 netif_trans_update(dev);
1241                 dev_watchdog_up(dev);
1242         }
1243 }
1244 EXPORT_SYMBOL(dev_activate);
1245
1246 static void qdisc_deactivate(struct Qdisc *qdisc)
1247 {
1248         if (qdisc->flags & TCQ_F_BUILTIN)
1249                 return;
1250
1251         set_bit(__QDISC_STATE_DEACTIVATED, &qdisc->state);
1252 }
1253
1254 static void dev_deactivate_queue(struct net_device *dev,
1255                                  struct netdev_queue *dev_queue,
1256                                  void *_qdisc_default)
1257 {
1258         struct Qdisc *qdisc_default = _qdisc_default;
1259         struct Qdisc *qdisc;
1260
1261         qdisc = rtnl_dereference(dev_queue->qdisc);
1262         if (qdisc) {
1263                 qdisc_deactivate(qdisc);
1264                 rcu_assign_pointer(dev_queue->qdisc, qdisc_default);
1265         }
1266 }
1267
1268 static void dev_reset_queue(struct net_device *dev,
1269                             struct netdev_queue *dev_queue,
1270                             void *_unused)
1271 {
1272         struct Qdisc *qdisc;
1273         bool nolock;
1274
1275         qdisc = dev_queue->qdisc_sleeping;
1276         if (!qdisc)
1277                 return;
1278
1279         nolock = qdisc->flags & TCQ_F_NOLOCK;
1280
1281         if (nolock)
1282                 spin_lock_bh(&qdisc->seqlock);
1283         spin_lock_bh(qdisc_lock(qdisc));
1284
1285         qdisc_reset(qdisc);
1286
1287         spin_unlock_bh(qdisc_lock(qdisc));
1288         if (nolock) {
1289                 clear_bit(__QDISC_STATE_MISSED, &qdisc->state);
1290                 clear_bit(__QDISC_STATE_DRAINING, &qdisc->state);
1291                 spin_unlock_bh(&qdisc->seqlock);
1292         }
1293 }
1294
1295 static bool some_qdisc_is_busy(struct net_device *dev)
1296 {
1297         unsigned int i;
1298
1299         for (i = 0; i < dev->num_tx_queues; i++) {
1300                 struct netdev_queue *dev_queue;
1301                 spinlock_t *root_lock;
1302                 struct Qdisc *q;
1303                 int val;
1304
1305                 dev_queue = netdev_get_tx_queue(dev, i);
1306                 q = dev_queue->qdisc_sleeping;
1307
1308                 root_lock = qdisc_lock(q);
1309                 spin_lock_bh(root_lock);
1310
1311                 val = (qdisc_is_running(q) ||
1312                        test_bit(__QDISC_STATE_SCHED, &q->state));
1313
1314                 spin_unlock_bh(root_lock);
1315
1316                 if (val)
1317                         return true;
1318         }
1319         return false;
1320 }
1321
1322 /**
1323  *      dev_deactivate_many - deactivate transmissions on several devices
1324  *      @head: list of devices to deactivate
1325  *
1326  *      This function returns only when all outstanding transmissions
1327  *      have completed, unless all devices are in dismantle phase.
1328  */
1329 void dev_deactivate_many(struct list_head *head)
1330 {
1331         struct net_device *dev;
1332
1333         list_for_each_entry(dev, head, close_list) {
1334                 netdev_for_each_tx_queue(dev, dev_deactivate_queue,
1335                                          &noop_qdisc);
1336                 if (dev_ingress_queue(dev))
1337                         dev_deactivate_queue(dev, dev_ingress_queue(dev),
1338                                              &noop_qdisc);
1339
1340                 dev_watchdog_down(dev);
1341         }
1342
1343         /* Wait for outstanding qdisc-less dev_queue_xmit calls or
1344          * outstanding qdisc enqueuing calls.
1345          * This is avoided if all devices are in dismantle phase :
1346          * Caller will call synchronize_net() for us
1347          */
1348         synchronize_net();
1349
1350         list_for_each_entry(dev, head, close_list) {
1351                 netdev_for_each_tx_queue(dev, dev_reset_queue, NULL);
1352
1353                 if (dev_ingress_queue(dev))
1354                         dev_reset_queue(dev, dev_ingress_queue(dev), NULL);
1355         }
1356
1357         /* Wait for outstanding qdisc_run calls. */
1358         list_for_each_entry(dev, head, close_list) {
1359                 while (some_qdisc_is_busy(dev)) {
1360                         /* wait_event() would avoid this sleep-loop but would
1361                          * require expensive checks in the fast paths of packet
1362                          * processing which isn't worth it.
1363                          */
1364                         schedule_timeout_uninterruptible(1);
1365                 }
1366         }
1367 }
1368
1369 void dev_deactivate(struct net_device *dev)
1370 {
1371         LIST_HEAD(single);
1372
1373         list_add(&dev->close_list, &single);
1374         dev_deactivate_many(&single);
1375         list_del(&single);
1376 }
1377 EXPORT_SYMBOL(dev_deactivate);
1378
1379 static int qdisc_change_tx_queue_len(struct net_device *dev,
1380                                      struct netdev_queue *dev_queue)
1381 {
1382         struct Qdisc *qdisc = dev_queue->qdisc_sleeping;
1383         const struct Qdisc_ops *ops = qdisc->ops;
1384
1385         if (ops->change_tx_queue_len)
1386                 return ops->change_tx_queue_len(qdisc, dev->tx_queue_len);
1387         return 0;
1388 }
1389
1390 void dev_qdisc_change_real_num_tx(struct net_device *dev,
1391                                   unsigned int new_real_tx)
1392 {
1393         struct Qdisc *qdisc = rtnl_dereference(dev->qdisc);
1394
1395         if (qdisc->ops->change_real_num_tx)
1396                 qdisc->ops->change_real_num_tx(qdisc, new_real_tx);
1397 }
1398
1399 void mq_change_real_num_tx(struct Qdisc *sch, unsigned int new_real_tx)
1400 {
1401 #ifdef CONFIG_NET_SCHED
1402         struct net_device *dev = qdisc_dev(sch);
1403         struct Qdisc *qdisc;
1404         unsigned int i;
1405
1406         for (i = new_real_tx; i < dev->real_num_tx_queues; i++) {
1407                 qdisc = netdev_get_tx_queue(dev, i)->qdisc_sleeping;
1408                 /* Only update the default qdiscs we created,
1409                  * qdiscs with handles are always hashed.
1410                  */
1411                 if (qdisc != &noop_qdisc && !qdisc->handle)
1412                         qdisc_hash_del(qdisc);
1413         }
1414         for (i = dev->real_num_tx_queues; i < new_real_tx; i++) {
1415                 qdisc = netdev_get_tx_queue(dev, i)->qdisc_sleeping;
1416                 if (qdisc != &noop_qdisc && !qdisc->handle)
1417                         qdisc_hash_add(qdisc, false);
1418         }
1419 #endif
1420 }
1421 EXPORT_SYMBOL(mq_change_real_num_tx);
1422
1423 int dev_qdisc_change_tx_queue_len(struct net_device *dev)
1424 {
1425         bool up = dev->flags & IFF_UP;
1426         unsigned int i;
1427         int ret = 0;
1428
1429         if (up)
1430                 dev_deactivate(dev);
1431
1432         for (i = 0; i < dev->num_tx_queues; i++) {
1433                 ret = qdisc_change_tx_queue_len(dev, &dev->_tx[i]);
1434
1435                 /* TODO: revert changes on a partial failure */
1436                 if (ret)
1437                         break;
1438         }
1439
1440         if (up)
1441                 dev_activate(dev);
1442         return ret;
1443 }
1444
1445 static void dev_init_scheduler_queue(struct net_device *dev,
1446                                      struct netdev_queue *dev_queue,
1447                                      void *_qdisc)
1448 {
1449         struct Qdisc *qdisc = _qdisc;
1450
1451         rcu_assign_pointer(dev_queue->qdisc, qdisc);
1452         dev_queue->qdisc_sleeping = qdisc;
1453 }
1454
1455 void dev_init_scheduler(struct net_device *dev)
1456 {
1457         rcu_assign_pointer(dev->qdisc, &noop_qdisc);
1458         netdev_for_each_tx_queue(dev, dev_init_scheduler_queue, &noop_qdisc);
1459         if (dev_ingress_queue(dev))
1460                 dev_init_scheduler_queue(dev, dev_ingress_queue(dev), &noop_qdisc);
1461
1462         timer_setup(&dev->watchdog_timer, dev_watchdog, 0);
1463 }
1464
1465 void dev_shutdown(struct net_device *dev)
1466 {
1467         netdev_for_each_tx_queue(dev, shutdown_scheduler_queue, &noop_qdisc);
1468         if (dev_ingress_queue(dev))
1469                 shutdown_scheduler_queue(dev, dev_ingress_queue(dev), &noop_qdisc);
1470         qdisc_put(rtnl_dereference(dev->qdisc));
1471         rcu_assign_pointer(dev->qdisc, &noop_qdisc);
1472
1473         WARN_ON(timer_pending(&dev->watchdog_timer));
1474 }
1475
1476 /**
1477  * psched_ratecfg_precompute__() - Pre-compute values for reciprocal division
1478  * @rate:   Rate to compute reciprocal division values of
1479  * @mult:   Multiplier for reciprocal division
1480  * @shift:  Shift for reciprocal division
1481  *
1482  * The multiplier and shift for reciprocal division by rate are stored
1483  * in mult and shift.
1484  *
1485  * The deal here is to replace a divide by a reciprocal one
1486  * in fast path (a reciprocal divide is a multiply and a shift)
1487  *
1488  * Normal formula would be :
1489  *  time_in_ns = (NSEC_PER_SEC * len) / rate_bps
1490  *
1491  * We compute mult/shift to use instead :
1492  *  time_in_ns = (len * mult) >> shift;
1493  *
1494  * We try to get the highest possible mult value for accuracy,
1495  * but have to make sure no overflows will ever happen.
1496  *
1497  * reciprocal_value() is not used here it doesn't handle 64-bit values.
1498  */
1499 static void psched_ratecfg_precompute__(u64 rate, u32 *mult, u8 *shift)
1500 {
1501         u64 factor = NSEC_PER_SEC;
1502
1503         *mult = 1;
1504         *shift = 0;
1505
1506         if (rate <= 0)
1507                 return;
1508
1509         for (;;) {
1510                 *mult = div64_u64(factor, rate);
1511                 if (*mult & (1U << 31) || factor & (1ULL << 63))
1512                         break;
1513                 factor <<= 1;
1514                 (*shift)++;
1515         }
1516 }
1517
1518 void psched_ratecfg_precompute(struct psched_ratecfg *r,
1519                                const struct tc_ratespec *conf,
1520                                u64 rate64)
1521 {
1522         memset(r, 0, sizeof(*r));
1523         r->overhead = conf->overhead;
1524         r->mpu = conf->mpu;
1525         r->rate_bytes_ps = max_t(u64, conf->rate, rate64);
1526         r->linklayer = (conf->linklayer & TC_LINKLAYER_MASK);
1527         psched_ratecfg_precompute__(r->rate_bytes_ps, &r->mult, &r->shift);
1528 }
1529 EXPORT_SYMBOL(psched_ratecfg_precompute);
1530
1531 void psched_ppscfg_precompute(struct psched_pktrate *r, u64 pktrate64)
1532 {
1533         r->rate_pkts_ps = pktrate64;
1534         psched_ratecfg_precompute__(r->rate_pkts_ps, &r->mult, &r->shift);
1535 }
1536 EXPORT_SYMBOL(psched_ppscfg_precompute);
1537
1538 void mini_qdisc_pair_swap(struct mini_Qdisc_pair *miniqp,
1539                           struct tcf_proto *tp_head)
1540 {
1541         /* Protected with chain0->filter_chain_lock.
1542          * Can't access chain directly because tp_head can be NULL.
1543          */
1544         struct mini_Qdisc *miniq_old =
1545                 rcu_dereference_protected(*miniqp->p_miniq, 1);
1546         struct mini_Qdisc *miniq;
1547
1548         if (!tp_head) {
1549                 RCU_INIT_POINTER(*miniqp->p_miniq, NULL);
1550         } else {
1551                 miniq = miniq_old != &miniqp->miniq1 ?
1552                         &miniqp->miniq1 : &miniqp->miniq2;
1553
1554                 /* We need to make sure that readers won't see the miniq
1555                  * we are about to modify. So ensure that at least one RCU
1556                  * grace period has elapsed since the miniq was made
1557                  * inactive.
1558                  */
1559                 if (IS_ENABLED(CONFIG_PREEMPT_RT))
1560                         cond_synchronize_rcu(miniq->rcu_state);
1561                 else if (!poll_state_synchronize_rcu(miniq->rcu_state))
1562                         synchronize_rcu_expedited();
1563
1564                 miniq->filter_list = tp_head;
1565                 rcu_assign_pointer(*miniqp->p_miniq, miniq);
1566         }
1567
1568         if (miniq_old)
1569                 /* This is counterpart of the rcu sync above. We need to
1570                  * block potential new user of miniq_old until all readers
1571                  * are not seeing it.
1572                  */
1573                 miniq_old->rcu_state = start_poll_synchronize_rcu();
1574 }
1575 EXPORT_SYMBOL(mini_qdisc_pair_swap);
1576
1577 void mini_qdisc_pair_block_init(struct mini_Qdisc_pair *miniqp,
1578                                 struct tcf_block *block)
1579 {
1580         miniqp->miniq1.block = block;
1581         miniqp->miniq2.block = block;
1582 }
1583 EXPORT_SYMBOL(mini_qdisc_pair_block_init);
1584
1585 void mini_qdisc_pair_init(struct mini_Qdisc_pair *miniqp, struct Qdisc *qdisc,
1586                           struct mini_Qdisc __rcu **p_miniq)
1587 {
1588         miniqp->miniq1.cpu_bstats = qdisc->cpu_bstats;
1589         miniqp->miniq1.cpu_qstats = qdisc->cpu_qstats;
1590         miniqp->miniq2.cpu_bstats = qdisc->cpu_bstats;
1591         miniqp->miniq2.cpu_qstats = qdisc->cpu_qstats;
1592         miniqp->miniq1.rcu_state = get_state_synchronize_rcu();
1593         miniqp->miniq2.rcu_state = miniqp->miniq1.rcu_state;
1594         miniqp->p_miniq = p_miniq;
1595 }
1596 EXPORT_SYMBOL(mini_qdisc_pair_init);