1 /* 2 * net/sched/sch_generic.c Generic packet scheduler routines. 3 * 4 * This program is free software; you can redistribute it and/or 5 * modify it under the terms of the GNU General Public License 6 * as published by the Free Software Foundation; either version 7 * 2 of the License, or (at your option) any later version. 8 * 9 * Authors: Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru> 10 * Jamal Hadi Salim, <hadi@cyberus.ca> 990601 11 * - Ingress support 12 */ 13 14 #include <linux/bitops.h> 15 #include <linux/module.h> 16 #include <linux/types.h> 17 #include <linux/kernel.h> 18 #include <linux/sched.h> 19 #include <linux/string.h> 20 #include <linux/errno.h> 21 #include <linux/netdevice.h> 22 #include <linux/skbuff.h> 23 #include <linux/rtnetlink.h> 24 #include <linux/init.h> 25 #include <linux/rcupdate.h> 26 #include <linux/list.h> 27 #include <linux/slab.h> 28 #include <net/pkt_sched.h> 29 #include <net/dst.h> 30 31 /* Main transmission queue. */ 32 33 /* Modifications to data participating in scheduling must be protected with 34 * qdisc_lock(qdisc) spinlock. 35 * 36 * The idea is the following: 37 * - enqueue, dequeue are serialized via qdisc root lock 38 * - ingress filtering is also serialized via qdisc root lock 39 * - updates to tree and tree walking are only done under the rtnl mutex. 40 */ 41 42 static inline int dev_requeue_skb(struct sk_buff *skb, struct Qdisc *q) 43 { 44 skb_dst_force(skb); 45 q->gso_skb = skb; 46 q->qstats.requeues++; 47 q->q.qlen++; /* it's still part of the queue */ 48 __netif_schedule(q); 49 50 return 0; 51 } 52 53 static inline struct sk_buff *dequeue_skb(struct Qdisc *q) 54 { 55 struct sk_buff *skb = q->gso_skb; 56 57 if (unlikely(skb)) { 58 struct net_device *dev = qdisc_dev(q); 59 struct netdev_queue *txq; 60 61 /* check the reason of requeuing without tx lock first */ 62 txq = netdev_get_tx_queue(dev, skb_get_queue_mapping(skb)); 63 if (!netif_tx_queue_stopped(txq) && 64 !netif_tx_queue_frozen(txq)) { 65 q->gso_skb = NULL; 66 q->q.qlen--; 67 } else 68 skb = NULL; 69 } else { 70 skb = q->dequeue(q); 71 } 72 73 return skb; 74 } 75 76 static inline int handle_dev_cpu_collision(struct sk_buff *skb, 77 struct netdev_queue *dev_queue, 78 struct Qdisc *q) 79 { 80 int ret; 81 82 if (unlikely(dev_queue->xmit_lock_owner == smp_processor_id())) { 83 /* 84 * Same CPU holding the lock. It may be a transient 85 * configuration error, when hard_start_xmit() recurses. We 86 * detect it by checking xmit owner and drop the packet when 87 * deadloop is detected. Return OK to try the next skb. 88 */ 89 kfree_skb(skb); 90 if (net_ratelimit()) 91 printk(KERN_WARNING "Dead loop on netdevice %s, " 92 "fix it urgently!\n", dev_queue->dev->name); 93 ret = qdisc_qlen(q); 94 } else { 95 /* 96 * Another cpu is holding lock, requeue & delay xmits for 97 * some time. 98 */ 99 __get_cpu_var(softnet_data).cpu_collision++; 100 ret = dev_requeue_skb(skb, q); 101 } 102 103 return ret; 104 } 105 106 /* 107 * Transmit one skb, and handle the return status as required. Holding the 108 * __QDISC_STATE_RUNNING bit guarantees that only one CPU can execute this 109 * function. 110 * 111 * Returns to the caller: 112 * 0 - queue is empty or throttled. 113 * >0 - queue is not empty. 114 */ 115 int sch_direct_xmit(struct sk_buff *skb, struct Qdisc *q, 116 struct net_device *dev, struct netdev_queue *txq, 117 spinlock_t *root_lock) 118 { 119 int ret = NETDEV_TX_BUSY; 120 121 /* And release qdisc */ 122 spin_unlock(root_lock); 123 124 HARD_TX_LOCK(dev, txq, smp_processor_id()); 125 if (!netif_tx_queue_stopped(txq) && !netif_tx_queue_frozen(txq)) 126 ret = dev_hard_start_xmit(skb, dev, txq); 127 128 HARD_TX_UNLOCK(dev, txq); 129 130 spin_lock(root_lock); 131 132 if (dev_xmit_complete(ret)) { 133 /* Driver sent out skb successfully or skb was consumed */ 134 ret = qdisc_qlen(q); 135 } else if (ret == NETDEV_TX_LOCKED) { 136 /* Driver try lock failed */ 137 ret = handle_dev_cpu_collision(skb, txq, q); 138 } else { 139 /* Driver returned NETDEV_TX_BUSY - requeue skb */ 140 if (unlikely (ret != NETDEV_TX_BUSY && net_ratelimit())) 141 printk(KERN_WARNING "BUG %s code %d qlen %d\n", 142 dev->name, ret, q->q.qlen); 143 144 ret = dev_requeue_skb(skb, q); 145 } 146 147 if (ret && (netif_tx_queue_stopped(txq) || 148 netif_tx_queue_frozen(txq))) 149 ret = 0; 150 151 return ret; 152 } 153 154 /* 155 * NOTE: Called under qdisc_lock(q) with locally disabled BH. 156 * 157 * __QDISC_STATE_RUNNING guarantees only one CPU can process 158 * this qdisc at a time. qdisc_lock(q) serializes queue accesses for 159 * this queue. 160 * 161 * netif_tx_lock serializes accesses to device driver. 162 * 163 * qdisc_lock(q) and netif_tx_lock are mutually exclusive, 164 * if one is grabbed, another must be free. 165 * 166 * Note, that this procedure can be called by a watchdog timer 167 * 168 * Returns to the caller: 169 * 0 - queue is empty or throttled. 170 * >0 - queue is not empty. 171 * 172 */ 173 static inline int qdisc_restart(struct Qdisc *q) 174 { 175 struct netdev_queue *txq; 176 struct net_device *dev; 177 spinlock_t *root_lock; 178 struct sk_buff *skb; 179 180 /* Dequeue packet */ 181 skb = dequeue_skb(q); 182 if (unlikely(!skb)) 183 return 0; 184 WARN_ON_ONCE(skb_dst_is_noref(skb)); 185 root_lock = qdisc_lock(q); 186 dev = qdisc_dev(q); 187 txq = netdev_get_tx_queue(dev, skb_get_queue_mapping(skb)); 188 189 return sch_direct_xmit(skb, q, dev, txq, root_lock); 190 } 191 192 void __qdisc_run(struct Qdisc *q) 193 { 194 unsigned long start_time = jiffies; 195 196 while (qdisc_restart(q)) { 197 /* 198 * Postpone processing if 199 * 1. another process needs the CPU; 200 * 2. we've been doing it for too long. 201 */ 202 if (need_resched() || jiffies != start_time) { 203 __netif_schedule(q); 204 break; 205 } 206 } 207 208 qdisc_run_end(q); 209 } 210 211 unsigned long dev_trans_start(struct net_device *dev) 212 { 213 unsigned long val, res = dev->trans_start; 214 unsigned int i; 215 216 for (i = 0; i < dev->num_tx_queues; i++) { 217 val = netdev_get_tx_queue(dev, i)->trans_start; 218 if (val && time_after(val, res)) 219 res = val; 220 } 221 dev->trans_start = res; 222 return res; 223 } 224 EXPORT_SYMBOL(dev_trans_start); 225 226 static void dev_watchdog(unsigned long arg) 227 { 228 struct net_device *dev = (struct net_device *)arg; 229 230 netif_tx_lock(dev); 231 if (!qdisc_tx_is_noop(dev)) { 232 if (netif_device_present(dev) && 233 netif_running(dev) && 234 netif_carrier_ok(dev)) { 235 int some_queue_timedout = 0; 236 unsigned int i; 237 unsigned long trans_start; 238 239 for (i = 0; i < dev->num_tx_queues; i++) { 240 struct netdev_queue *txq; 241 242 txq = netdev_get_tx_queue(dev, i); 243 /* 244 * old device drivers set dev->trans_start 245 */ 246 trans_start = txq->trans_start ? : dev->trans_start; 247 if (netif_tx_queue_stopped(txq) && 248 time_after(jiffies, (trans_start + 249 dev->watchdog_timeo))) { 250 some_queue_timedout = 1; 251 break; 252 } 253 } 254 255 if (some_queue_timedout) { 256 char drivername[64]; 257 WARN_ONCE(1, KERN_INFO "NETDEV WATCHDOG: %s (%s): transmit queue %u timed out\n", 258 dev->name, netdev_drivername(dev, drivername, 64), i); 259 dev->netdev_ops->ndo_tx_timeout(dev); 260 } 261 if (!mod_timer(&dev->watchdog_timer, 262 round_jiffies(jiffies + 263 dev->watchdog_timeo))) 264 dev_hold(dev); 265 } 266 } 267 netif_tx_unlock(dev); 268 269 dev_put(dev); 270 } 271 272 void __netdev_watchdog_up(struct net_device *dev) 273 { 274 if (dev->netdev_ops->ndo_tx_timeout) { 275 if (dev->watchdog_timeo <= 0) 276 dev->watchdog_timeo = 5*HZ; 277 if (!mod_timer(&dev->watchdog_timer, 278 round_jiffies(jiffies + dev->watchdog_timeo))) 279 dev_hold(dev); 280 } 281 } 282 283 static void dev_watchdog_up(struct net_device *dev) 284 { 285 __netdev_watchdog_up(dev); 286 } 287 288 static void dev_watchdog_down(struct net_device *dev) 289 { 290 netif_tx_lock_bh(dev); 291 if (del_timer(&dev->watchdog_timer)) 292 dev_put(dev); 293 netif_tx_unlock_bh(dev); 294 } 295 296 /** 297 * netif_carrier_on - set carrier 298 * @dev: network device 299 * 300 * Device has detected that carrier. 301 */ 302 void netif_carrier_on(struct net_device *dev) 303 { 304 if (test_and_clear_bit(__LINK_STATE_NOCARRIER, &dev->state)) { 305 if (dev->reg_state == NETREG_UNINITIALIZED) 306 return; 307 linkwatch_fire_event(dev); 308 if (netif_running(dev)) 309 __netdev_watchdog_up(dev); 310 } 311 } 312 EXPORT_SYMBOL(netif_carrier_on); 313 314 /** 315 * netif_carrier_off - clear carrier 316 * @dev: network device 317 * 318 * Device has detected loss of carrier. 319 */ 320 void netif_carrier_off(struct net_device *dev) 321 { 322 if (!test_and_set_bit(__LINK_STATE_NOCARRIER, &dev->state)) { 323 if (dev->reg_state == NETREG_UNINITIALIZED) 324 return; 325 linkwatch_fire_event(dev); 326 } 327 } 328 EXPORT_SYMBOL(netif_carrier_off); 329 330 /** 331 * netif_notify_peers - notify network peers about existence of @dev 332 * @dev: network device 333 * 334 * Generate traffic such that interested network peers are aware of 335 * @dev, such as by generating a gratuitous ARP. This may be used when 336 * a device wants to inform the rest of the network about some sort of 337 * reconfiguration such as a failover event or virtual machine 338 * migration. 339 */ 340 void netif_notify_peers(struct net_device *dev) 341 { 342 rtnl_lock(); 343 call_netdevice_notifiers(NETDEV_NOTIFY_PEERS, dev); 344 rtnl_unlock(); 345 } 346 EXPORT_SYMBOL(netif_notify_peers); 347 348 /* "NOOP" scheduler: the best scheduler, recommended for all interfaces 349 under all circumstances. It is difficult to invent anything faster or 350 cheaper. 351 */ 352 353 static int noop_enqueue(struct sk_buff *skb, struct Qdisc * qdisc) 354 { 355 kfree_skb(skb); 356 return NET_XMIT_CN; 357 } 358 359 static struct sk_buff *noop_dequeue(struct Qdisc * qdisc) 360 { 361 return NULL; 362 } 363 364 struct Qdisc_ops noop_qdisc_ops __read_mostly = { 365 .id = "noop", 366 .priv_size = 0, 367 .enqueue = noop_enqueue, 368 .dequeue = noop_dequeue, 369 .peek = noop_dequeue, 370 .owner = THIS_MODULE, 371 }; 372 373 static struct netdev_queue noop_netdev_queue = { 374 .qdisc = &noop_qdisc, 375 .qdisc_sleeping = &noop_qdisc, 376 }; 377 378 struct Qdisc noop_qdisc = { 379 .enqueue = noop_enqueue, 380 .dequeue = noop_dequeue, 381 .flags = TCQ_F_BUILTIN, 382 .ops = &noop_qdisc_ops, 383 .list = LIST_HEAD_INIT(noop_qdisc.list), 384 .q.lock = __SPIN_LOCK_UNLOCKED(noop_qdisc.q.lock), 385 .dev_queue = &noop_netdev_queue, 386 }; 387 EXPORT_SYMBOL(noop_qdisc); 388 389 static struct Qdisc_ops noqueue_qdisc_ops __read_mostly = { 390 .id = "noqueue", 391 .priv_size = 0, 392 .enqueue = noop_enqueue, 393 .dequeue = noop_dequeue, 394 .peek = noop_dequeue, 395 .owner = THIS_MODULE, 396 }; 397 398 static struct Qdisc noqueue_qdisc; 399 static struct netdev_queue noqueue_netdev_queue = { 400 .qdisc = &noqueue_qdisc, 401 .qdisc_sleeping = &noqueue_qdisc, 402 }; 403 404 static struct Qdisc noqueue_qdisc = { 405 .enqueue = NULL, 406 .dequeue = noop_dequeue, 407 .flags = TCQ_F_BUILTIN, 408 .ops = &noqueue_qdisc_ops, 409 .list = LIST_HEAD_INIT(noqueue_qdisc.list), 410 .q.lock = __SPIN_LOCK_UNLOCKED(noqueue_qdisc.q.lock), 411 .dev_queue = &noqueue_netdev_queue, 412 }; 413 414 415 static const u8 prio2band[TC_PRIO_MAX+1] = 416 { 1, 2, 2, 2, 1, 2, 0, 0 , 1, 1, 1, 1, 1, 1, 1, 1 }; 417 418 /* 3-band FIFO queue: old style, but should be a bit faster than 419 generic prio+fifo combination. 420 */ 421 422 #define PFIFO_FAST_BANDS 3 423 424 /* 425 * Private data for a pfifo_fast scheduler containing: 426 * - queues for the three band 427 * - bitmap indicating which of the bands contain skbs 428 */ 429 struct pfifo_fast_priv { 430 u32 bitmap; 431 struct sk_buff_head q[PFIFO_FAST_BANDS]; 432 }; 433 434 /* 435 * Convert a bitmap to the first band number where an skb is queued, where: 436 * bitmap=0 means there are no skbs on any band. 437 * bitmap=1 means there is an skb on band 0. 438 * bitmap=7 means there are skbs on all 3 bands, etc. 439 */ 440 static const int bitmap2band[] = {-1, 0, 1, 0, 2, 0, 1, 0}; 441 442 static inline struct sk_buff_head *band2list(struct pfifo_fast_priv *priv, 443 int band) 444 { 445 return priv->q + band; 446 } 447 448 static int pfifo_fast_enqueue(struct sk_buff *skb, struct Qdisc* qdisc) 449 { 450 if (skb_queue_len(&qdisc->q) < qdisc_dev(qdisc)->tx_queue_len) { 451 int band = prio2band[skb->priority & TC_PRIO_MAX]; 452 struct pfifo_fast_priv *priv = qdisc_priv(qdisc); 453 struct sk_buff_head *list = band2list(priv, band); 454 455 priv->bitmap |= (1 << band); 456 qdisc->q.qlen++; 457 return __qdisc_enqueue_tail(skb, qdisc, list); 458 } 459 460 return qdisc_drop(skb, qdisc); 461 } 462 463 static struct sk_buff *pfifo_fast_dequeue(struct Qdisc* qdisc) 464 { 465 struct pfifo_fast_priv *priv = qdisc_priv(qdisc); 466 int band = bitmap2band[priv->bitmap]; 467 468 if (likely(band >= 0)) { 469 struct sk_buff_head *list = band2list(priv, band); 470 struct sk_buff *skb = __qdisc_dequeue_head(qdisc, list); 471 472 qdisc->q.qlen--; 473 if (skb_queue_empty(list)) 474 priv->bitmap &= ~(1 << band); 475 476 return skb; 477 } 478 479 return NULL; 480 } 481 482 static struct sk_buff *pfifo_fast_peek(struct Qdisc* qdisc) 483 { 484 struct pfifo_fast_priv *priv = qdisc_priv(qdisc); 485 int band = bitmap2band[priv->bitmap]; 486 487 if (band >= 0) { 488 struct sk_buff_head *list = band2list(priv, band); 489 490 return skb_peek(list); 491 } 492 493 return NULL; 494 } 495 496 static void pfifo_fast_reset(struct Qdisc* qdisc) 497 { 498 int prio; 499 struct pfifo_fast_priv *priv = qdisc_priv(qdisc); 500 501 for (prio = 0; prio < PFIFO_FAST_BANDS; prio++) 502 __qdisc_reset_queue(qdisc, band2list(priv, prio)); 503 504 priv->bitmap = 0; 505 qdisc->qstats.backlog = 0; 506 qdisc->q.qlen = 0; 507 } 508 509 static int pfifo_fast_dump(struct Qdisc *qdisc, struct sk_buff *skb) 510 { 511 struct tc_prio_qopt opt = { .bands = PFIFO_FAST_BANDS }; 512 513 memcpy(&opt.priomap, prio2band, TC_PRIO_MAX+1); 514 NLA_PUT(skb, TCA_OPTIONS, sizeof(opt), &opt); 515 return skb->len; 516 517 nla_put_failure: 518 return -1; 519 } 520 521 static int pfifo_fast_init(struct Qdisc *qdisc, struct nlattr *opt) 522 { 523 int prio; 524 struct pfifo_fast_priv *priv = qdisc_priv(qdisc); 525 526 for (prio = 0; prio < PFIFO_FAST_BANDS; prio++) 527 skb_queue_head_init(band2list(priv, prio)); 528 529 return 0; 530 } 531 532 struct Qdisc_ops pfifo_fast_ops __read_mostly = { 533 .id = "pfifo_fast", 534 .priv_size = sizeof(struct pfifo_fast_priv), 535 .enqueue = pfifo_fast_enqueue, 536 .dequeue = pfifo_fast_dequeue, 537 .peek = pfifo_fast_peek, 538 .init = pfifo_fast_init, 539 .reset = pfifo_fast_reset, 540 .dump = pfifo_fast_dump, 541 .owner = THIS_MODULE, 542 }; 543 544 struct Qdisc *qdisc_alloc(struct netdev_queue *dev_queue, 545 struct Qdisc_ops *ops) 546 { 547 void *p; 548 struct Qdisc *sch; 549 unsigned int size; 550 int err = -ENOBUFS; 551 552 /* ensure that the Qdisc and the private data are 64-byte aligned */ 553 size = QDISC_ALIGN(sizeof(*sch)); 554 size += ops->priv_size + (QDISC_ALIGNTO - 1); 555 556 p = kzalloc(size, GFP_KERNEL); 557 if (!p) 558 goto errout; 559 sch = (struct Qdisc *) QDISC_ALIGN((unsigned long) p); 560 sch->padded = (char *) sch - (char *) p; 561 562 INIT_LIST_HEAD(&sch->list); 563 skb_queue_head_init(&sch->q); 564 sch->ops = ops; 565 sch->enqueue = ops->enqueue; 566 sch->dequeue = ops->dequeue; 567 sch->dev_queue = dev_queue; 568 dev_hold(qdisc_dev(sch)); 569 atomic_set(&sch->refcnt, 1); 570 571 return sch; 572 errout: 573 return ERR_PTR(err); 574 } 575 576 struct Qdisc * qdisc_create_dflt(struct net_device *dev, 577 struct netdev_queue *dev_queue, 578 struct Qdisc_ops *ops, 579 unsigned int parentid) 580 { 581 struct Qdisc *sch; 582 583 sch = qdisc_alloc(dev_queue, ops); 584 if (IS_ERR(sch)) 585 goto errout; 586 sch->parent = parentid; 587 588 if (!ops->init || ops->init(sch, NULL) == 0) 589 return sch; 590 591 qdisc_destroy(sch); 592 errout: 593 return NULL; 594 } 595 EXPORT_SYMBOL(qdisc_create_dflt); 596 597 /* Under qdisc_lock(qdisc) and BH! */ 598 599 void qdisc_reset(struct Qdisc *qdisc) 600 { 601 const struct Qdisc_ops *ops = qdisc->ops; 602 603 if (ops->reset) 604 ops->reset(qdisc); 605 606 if (qdisc->gso_skb) { 607 kfree_skb(qdisc->gso_skb); 608 qdisc->gso_skb = NULL; 609 qdisc->q.qlen = 0; 610 } 611 } 612 EXPORT_SYMBOL(qdisc_reset); 613 614 static void qdisc_rcu_free(struct rcu_head *head) 615 { 616 struct Qdisc *qdisc = container_of(head, struct Qdisc, rcu_head); 617 618 kfree((char *) qdisc - qdisc->padded); 619 } 620 621 void qdisc_destroy(struct Qdisc *qdisc) 622 { 623 const struct Qdisc_ops *ops = qdisc->ops; 624 625 if (qdisc->flags & TCQ_F_BUILTIN || 626 !atomic_dec_and_test(&qdisc->refcnt)) 627 return; 628 629 #ifdef CONFIG_NET_SCHED 630 qdisc_list_del(qdisc); 631 632 qdisc_put_stab(qdisc->stab); 633 #endif 634 gen_kill_estimator(&qdisc->bstats, &qdisc->rate_est); 635 if (ops->reset) 636 ops->reset(qdisc); 637 if (ops->destroy) 638 ops->destroy(qdisc); 639 640 module_put(ops->owner); 641 dev_put(qdisc_dev(qdisc)); 642 643 kfree_skb(qdisc->gso_skb); 644 /* 645 * gen_estimator est_timer() might access qdisc->q.lock, 646 * wait a RCU grace period before freeing qdisc. 647 */ 648 call_rcu(&qdisc->rcu_head, qdisc_rcu_free); 649 } 650 EXPORT_SYMBOL(qdisc_destroy); 651 652 /* Attach toplevel qdisc to device queue. */ 653 struct Qdisc *dev_graft_qdisc(struct netdev_queue *dev_queue, 654 struct Qdisc *qdisc) 655 { 656 struct Qdisc *oqdisc = dev_queue->qdisc_sleeping; 657 spinlock_t *root_lock; 658 659 root_lock = qdisc_lock(oqdisc); 660 spin_lock_bh(root_lock); 661 662 /* Prune old scheduler */ 663 if (oqdisc && atomic_read(&oqdisc->refcnt) <= 1) 664 qdisc_reset(oqdisc); 665 666 /* ... and graft new one */ 667 if (qdisc == NULL) 668 qdisc = &noop_qdisc; 669 dev_queue->qdisc_sleeping = qdisc; 670 rcu_assign_pointer(dev_queue->qdisc, &noop_qdisc); 671 672 spin_unlock_bh(root_lock); 673 674 return oqdisc; 675 } 676 677 static void attach_one_default_qdisc(struct net_device *dev, 678 struct netdev_queue *dev_queue, 679 void *_unused) 680 { 681 struct Qdisc *qdisc; 682 683 if (dev->tx_queue_len) { 684 qdisc = qdisc_create_dflt(dev, dev_queue, 685 &pfifo_fast_ops, TC_H_ROOT); 686 if (!qdisc) { 687 printk(KERN_INFO "%s: activation failed\n", dev->name); 688 return; 689 } 690 691 /* Can by-pass the queue discipline for default qdisc */ 692 qdisc->flags |= TCQ_F_CAN_BYPASS; 693 } else { 694 qdisc = &noqueue_qdisc; 695 } 696 dev_queue->qdisc_sleeping = qdisc; 697 } 698 699 static void attach_default_qdiscs(struct net_device *dev) 700 { 701 struct netdev_queue *txq; 702 struct Qdisc *qdisc; 703 704 txq = netdev_get_tx_queue(dev, 0); 705 706 if (!netif_is_multiqueue(dev) || dev->tx_queue_len == 0) { 707 netdev_for_each_tx_queue(dev, attach_one_default_qdisc, NULL); 708 dev->qdisc = txq->qdisc_sleeping; 709 atomic_inc(&dev->qdisc->refcnt); 710 } else { 711 qdisc = qdisc_create_dflt(dev, txq, &mq_qdisc_ops, TC_H_ROOT); 712 if (qdisc) { 713 qdisc->ops->attach(qdisc); 714 dev->qdisc = qdisc; 715 } 716 } 717 } 718 719 static void transition_one_qdisc(struct net_device *dev, 720 struct netdev_queue *dev_queue, 721 void *_need_watchdog) 722 { 723 struct Qdisc *new_qdisc = dev_queue->qdisc_sleeping; 724 int *need_watchdog_p = _need_watchdog; 725 726 if (!(new_qdisc->flags & TCQ_F_BUILTIN)) 727 clear_bit(__QDISC_STATE_DEACTIVATED, &new_qdisc->state); 728 729 rcu_assign_pointer(dev_queue->qdisc, new_qdisc); 730 if (need_watchdog_p && new_qdisc != &noqueue_qdisc) { 731 dev_queue->trans_start = 0; 732 *need_watchdog_p = 1; 733 } 734 } 735 736 void dev_activate(struct net_device *dev) 737 { 738 int need_watchdog; 739 740 /* No queueing discipline is attached to device; 741 create default one i.e. pfifo_fast for devices, 742 which need queueing and noqueue_qdisc for 743 virtual interfaces 744 */ 745 746 if (dev->qdisc == &noop_qdisc) 747 attach_default_qdiscs(dev); 748 749 if (!netif_carrier_ok(dev)) 750 /* Delay activation until next carrier-on event */ 751 return; 752 753 need_watchdog = 0; 754 netdev_for_each_tx_queue(dev, transition_one_qdisc, &need_watchdog); 755 transition_one_qdisc(dev, &dev->rx_queue, NULL); 756 757 if (need_watchdog) { 758 dev->trans_start = jiffies; 759 dev_watchdog_up(dev); 760 } 761 } 762 763 static void dev_deactivate_queue(struct net_device *dev, 764 struct netdev_queue *dev_queue, 765 void *_qdisc_default) 766 { 767 struct Qdisc *qdisc_default = _qdisc_default; 768 struct Qdisc *qdisc; 769 770 qdisc = dev_queue->qdisc; 771 if (qdisc) { 772 spin_lock_bh(qdisc_lock(qdisc)); 773 774 if (!(qdisc->flags & TCQ_F_BUILTIN)) 775 set_bit(__QDISC_STATE_DEACTIVATED, &qdisc->state); 776 777 rcu_assign_pointer(dev_queue->qdisc, qdisc_default); 778 qdisc_reset(qdisc); 779 780 spin_unlock_bh(qdisc_lock(qdisc)); 781 } 782 } 783 784 static bool some_qdisc_is_busy(struct net_device *dev) 785 { 786 unsigned int i; 787 788 for (i = 0; i < dev->num_tx_queues; i++) { 789 struct netdev_queue *dev_queue; 790 spinlock_t *root_lock; 791 struct Qdisc *q; 792 int val; 793 794 dev_queue = netdev_get_tx_queue(dev, i); 795 q = dev_queue->qdisc_sleeping; 796 root_lock = qdisc_lock(q); 797 798 spin_lock_bh(root_lock); 799 800 val = (qdisc_is_running(q) || 801 test_bit(__QDISC_STATE_SCHED, &q->state)); 802 803 spin_unlock_bh(root_lock); 804 805 if (val) 806 return true; 807 } 808 return false; 809 } 810 811 void dev_deactivate(struct net_device *dev) 812 { 813 netdev_for_each_tx_queue(dev, dev_deactivate_queue, &noop_qdisc); 814 dev_deactivate_queue(dev, &dev->rx_queue, &noop_qdisc); 815 816 dev_watchdog_down(dev); 817 818 /* Wait for outstanding qdisc-less dev_queue_xmit calls. */ 819 synchronize_rcu(); 820 821 /* Wait for outstanding qdisc_run calls. */ 822 while (some_qdisc_is_busy(dev)) 823 yield(); 824 } 825 826 static void dev_init_scheduler_queue(struct net_device *dev, 827 struct netdev_queue *dev_queue, 828 void *_qdisc) 829 { 830 struct Qdisc *qdisc = _qdisc; 831 832 dev_queue->qdisc = qdisc; 833 dev_queue->qdisc_sleeping = qdisc; 834 } 835 836 void dev_init_scheduler(struct net_device *dev) 837 { 838 dev->qdisc = &noop_qdisc; 839 netdev_for_each_tx_queue(dev, dev_init_scheduler_queue, &noop_qdisc); 840 dev_init_scheduler_queue(dev, &dev->rx_queue, &noop_qdisc); 841 842 setup_timer(&dev->watchdog_timer, dev_watchdog, (unsigned long)dev); 843 } 844 845 static void shutdown_scheduler_queue(struct net_device *dev, 846 struct netdev_queue *dev_queue, 847 void *_qdisc_default) 848 { 849 struct Qdisc *qdisc = dev_queue->qdisc_sleeping; 850 struct Qdisc *qdisc_default = _qdisc_default; 851 852 if (qdisc) { 853 rcu_assign_pointer(dev_queue->qdisc, qdisc_default); 854 dev_queue->qdisc_sleeping = qdisc_default; 855 856 qdisc_destroy(qdisc); 857 } 858 } 859 860 void dev_shutdown(struct net_device *dev) 861 { 862 netdev_for_each_tx_queue(dev, shutdown_scheduler_queue, &noop_qdisc); 863 shutdown_scheduler_queue(dev, &dev->rx_queue, &noop_qdisc); 864 qdisc_destroy(dev->qdisc); 865 dev->qdisc = &noop_qdisc; 866 867 WARN_ON(timer_pending(&dev->watchdog_timer)); 868 } 869