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 <net/pkt_sched.h> 28 29 /* Main transmission queue. */ 30 31 /* Modifications to data participating in scheduling must be protected with 32 * dev->queue_lock spinlock. 33 * 34 * The idea is the following: 35 * - enqueue, dequeue are serialized via top level device 36 * spinlock dev->queue_lock. 37 * - ingress filtering is serialized via top level device 38 * spinlock dev->ingress_lock. 39 * - updates to tree and tree walking are only done under the rtnl mutex. 40 */ 41 42 void qdisc_lock_tree(struct net_device *dev) 43 { 44 spin_lock_bh(&dev->queue_lock); 45 spin_lock(&dev->ingress_lock); 46 } 47 48 void qdisc_unlock_tree(struct net_device *dev) 49 { 50 spin_unlock(&dev->ingress_lock); 51 spin_unlock_bh(&dev->queue_lock); 52 } 53 54 static inline int qdisc_qlen(struct Qdisc *q) 55 { 56 return q->q.qlen; 57 } 58 59 static inline int dev_requeue_skb(struct sk_buff *skb, struct net_device *dev, 60 struct Qdisc *q) 61 { 62 if (unlikely(skb->next)) 63 dev->gso_skb = skb; 64 else 65 q->ops->requeue(skb, q); 66 67 netif_schedule(dev); 68 return 0; 69 } 70 71 static inline struct sk_buff *dev_dequeue_skb(struct net_device *dev, 72 struct Qdisc *q) 73 { 74 struct sk_buff *skb; 75 76 if ((skb = dev->gso_skb)) 77 dev->gso_skb = NULL; 78 else 79 skb = q->dequeue(q); 80 81 return skb; 82 } 83 84 static inline int handle_dev_cpu_collision(struct sk_buff *skb, 85 struct net_device *dev, 86 struct Qdisc *q) 87 { 88 int ret; 89 90 if (unlikely(dev->xmit_lock_owner == smp_processor_id())) { 91 /* 92 * Same CPU holding the lock. It may be a transient 93 * configuration error, when hard_start_xmit() recurses. We 94 * detect it by checking xmit owner and drop the packet when 95 * deadloop is detected. Return OK to try the next skb. 96 */ 97 kfree_skb(skb); 98 if (net_ratelimit()) 99 printk(KERN_WARNING "Dead loop on netdevice %s, " 100 "fix it urgently!\n", dev->name); 101 ret = qdisc_qlen(q); 102 } else { 103 /* 104 * Another cpu is holding lock, requeue & delay xmits for 105 * some time. 106 */ 107 __get_cpu_var(netdev_rx_stat).cpu_collision++; 108 ret = dev_requeue_skb(skb, dev, q); 109 } 110 111 return ret; 112 } 113 114 /* 115 * NOTE: Called under dev->queue_lock with locally disabled BH. 116 * 117 * __LINK_STATE_QDISC_RUNNING guarantees only one CPU can process this 118 * device at a time. dev->queue_lock serializes queue accesses for 119 * this device AND dev->qdisc pointer itself. 120 * 121 * netif_tx_lock serializes accesses to device driver. 122 * 123 * dev->queue_lock and netif_tx_lock are mutually exclusive, 124 * if one is grabbed, another must be free. 125 * 126 * Note, that this procedure can be called by a watchdog timer 127 * 128 * Returns to the caller: 129 * 0 - queue is empty or throttled. 130 * >0 - queue is not empty. 131 * 132 */ 133 static inline int qdisc_restart(struct net_device *dev) 134 { 135 struct Qdisc *q = dev->qdisc; 136 struct sk_buff *skb; 137 int ret; 138 139 /* Dequeue packet */ 140 if (unlikely((skb = dev_dequeue_skb(dev, q)) == NULL)) 141 return 0; 142 143 144 /* And release queue */ 145 spin_unlock(&dev->queue_lock); 146 147 HARD_TX_LOCK(dev, smp_processor_id()); 148 ret = dev_hard_start_xmit(skb, dev); 149 HARD_TX_UNLOCK(dev); 150 151 spin_lock(&dev->queue_lock); 152 q = dev->qdisc; 153 154 switch (ret) { 155 case NETDEV_TX_OK: 156 /* Driver sent out skb successfully */ 157 ret = qdisc_qlen(q); 158 break; 159 160 case NETDEV_TX_LOCKED: 161 /* Driver try lock failed */ 162 ret = handle_dev_cpu_collision(skb, dev, q); 163 break; 164 165 default: 166 /* Driver returned NETDEV_TX_BUSY - requeue skb */ 167 if (unlikely (ret != NETDEV_TX_BUSY && net_ratelimit())) 168 printk(KERN_WARNING "BUG %s code %d qlen %d\n", 169 dev->name, ret, q->q.qlen); 170 171 ret = dev_requeue_skb(skb, dev, q); 172 break; 173 } 174 175 return ret; 176 } 177 178 void __qdisc_run(struct net_device *dev) 179 { 180 do { 181 if (!qdisc_restart(dev)) 182 break; 183 } while (!netif_queue_stopped(dev)); 184 185 clear_bit(__LINK_STATE_QDISC_RUNNING, &dev->state); 186 } 187 188 static void dev_watchdog(unsigned long arg) 189 { 190 struct net_device *dev = (struct net_device *)arg; 191 192 netif_tx_lock(dev); 193 if (dev->qdisc != &noop_qdisc) { 194 if (netif_device_present(dev) && 195 netif_running(dev) && 196 netif_carrier_ok(dev)) { 197 if (netif_queue_stopped(dev) && 198 time_after(jiffies, dev->trans_start + dev->watchdog_timeo)) { 199 200 printk(KERN_INFO "NETDEV WATCHDOG: %s: transmit timed out\n", 201 dev->name); 202 dev->tx_timeout(dev); 203 } 204 if (!mod_timer(&dev->watchdog_timer, round_jiffies(jiffies + dev->watchdog_timeo))) 205 dev_hold(dev); 206 } 207 } 208 netif_tx_unlock(dev); 209 210 dev_put(dev); 211 } 212 213 static void dev_watchdog_init(struct net_device *dev) 214 { 215 init_timer(&dev->watchdog_timer); 216 dev->watchdog_timer.data = (unsigned long)dev; 217 dev->watchdog_timer.function = dev_watchdog; 218 } 219 220 void __netdev_watchdog_up(struct net_device *dev) 221 { 222 if (dev->tx_timeout) { 223 if (dev->watchdog_timeo <= 0) 224 dev->watchdog_timeo = 5*HZ; 225 if (!mod_timer(&dev->watchdog_timer, 226 round_jiffies(jiffies + dev->watchdog_timeo))) 227 dev_hold(dev); 228 } 229 } 230 231 static void dev_watchdog_up(struct net_device *dev) 232 { 233 __netdev_watchdog_up(dev); 234 } 235 236 static void dev_watchdog_down(struct net_device *dev) 237 { 238 netif_tx_lock_bh(dev); 239 if (del_timer(&dev->watchdog_timer)) 240 dev_put(dev); 241 netif_tx_unlock_bh(dev); 242 } 243 244 /** 245 * netif_carrier_on - set carrier 246 * @dev: network device 247 * 248 * Device has detected that carrier. 249 */ 250 void netif_carrier_on(struct net_device *dev) 251 { 252 if (test_and_clear_bit(__LINK_STATE_NOCARRIER, &dev->state)) { 253 linkwatch_fire_event(dev); 254 if (netif_running(dev)) 255 __netdev_watchdog_up(dev); 256 } 257 } 258 259 /** 260 * netif_carrier_off - clear carrier 261 * @dev: network device 262 * 263 * Device has detected loss of carrier. 264 */ 265 void netif_carrier_off(struct net_device *dev) 266 { 267 if (!test_and_set_bit(__LINK_STATE_NOCARRIER, &dev->state)) 268 linkwatch_fire_event(dev); 269 } 270 271 /* "NOOP" scheduler: the best scheduler, recommended for all interfaces 272 under all circumstances. It is difficult to invent anything faster or 273 cheaper. 274 */ 275 276 static int noop_enqueue(struct sk_buff *skb, struct Qdisc * qdisc) 277 { 278 kfree_skb(skb); 279 return NET_XMIT_CN; 280 } 281 282 static struct sk_buff *noop_dequeue(struct Qdisc * qdisc) 283 { 284 return NULL; 285 } 286 287 static int noop_requeue(struct sk_buff *skb, struct Qdisc* qdisc) 288 { 289 if (net_ratelimit()) 290 printk(KERN_DEBUG "%s deferred output. It is buggy.\n", 291 skb->dev->name); 292 kfree_skb(skb); 293 return NET_XMIT_CN; 294 } 295 296 struct Qdisc_ops noop_qdisc_ops = { 297 .id = "noop", 298 .priv_size = 0, 299 .enqueue = noop_enqueue, 300 .dequeue = noop_dequeue, 301 .requeue = noop_requeue, 302 .owner = THIS_MODULE, 303 }; 304 305 struct Qdisc noop_qdisc = { 306 .enqueue = noop_enqueue, 307 .dequeue = noop_dequeue, 308 .flags = TCQ_F_BUILTIN, 309 .ops = &noop_qdisc_ops, 310 .list = LIST_HEAD_INIT(noop_qdisc.list), 311 }; 312 313 static struct Qdisc_ops noqueue_qdisc_ops = { 314 .id = "noqueue", 315 .priv_size = 0, 316 .enqueue = noop_enqueue, 317 .dequeue = noop_dequeue, 318 .requeue = noop_requeue, 319 .owner = THIS_MODULE, 320 }; 321 322 static struct Qdisc noqueue_qdisc = { 323 .enqueue = NULL, 324 .dequeue = noop_dequeue, 325 .flags = TCQ_F_BUILTIN, 326 .ops = &noqueue_qdisc_ops, 327 .list = LIST_HEAD_INIT(noqueue_qdisc.list), 328 }; 329 330 331 static const u8 prio2band[TC_PRIO_MAX+1] = 332 { 1, 2, 2, 2, 1, 2, 0, 0 , 1, 1, 1, 1, 1, 1, 1, 1 }; 333 334 /* 3-band FIFO queue: old style, but should be a bit faster than 335 generic prio+fifo combination. 336 */ 337 338 #define PFIFO_FAST_BANDS 3 339 340 static inline struct sk_buff_head *prio2list(struct sk_buff *skb, 341 struct Qdisc *qdisc) 342 { 343 struct sk_buff_head *list = qdisc_priv(qdisc); 344 return list + prio2band[skb->priority & TC_PRIO_MAX]; 345 } 346 347 static int pfifo_fast_enqueue(struct sk_buff *skb, struct Qdisc* qdisc) 348 { 349 struct sk_buff_head *list = prio2list(skb, qdisc); 350 351 if (skb_queue_len(list) < qdisc->dev->tx_queue_len) { 352 qdisc->q.qlen++; 353 return __qdisc_enqueue_tail(skb, qdisc, list); 354 } 355 356 return qdisc_drop(skb, qdisc); 357 } 358 359 static struct sk_buff *pfifo_fast_dequeue(struct Qdisc* qdisc) 360 { 361 int prio; 362 struct sk_buff_head *list = qdisc_priv(qdisc); 363 364 for (prio = 0; prio < PFIFO_FAST_BANDS; prio++) { 365 if (!skb_queue_empty(list + prio)) { 366 qdisc->q.qlen--; 367 return __qdisc_dequeue_head(qdisc, list + prio); 368 } 369 } 370 371 return NULL; 372 } 373 374 static int pfifo_fast_requeue(struct sk_buff *skb, struct Qdisc* qdisc) 375 { 376 qdisc->q.qlen++; 377 return __qdisc_requeue(skb, qdisc, prio2list(skb, qdisc)); 378 } 379 380 static void pfifo_fast_reset(struct Qdisc* qdisc) 381 { 382 int prio; 383 struct sk_buff_head *list = qdisc_priv(qdisc); 384 385 for (prio = 0; prio < PFIFO_FAST_BANDS; prio++) 386 __qdisc_reset_queue(qdisc, list + prio); 387 388 qdisc->qstats.backlog = 0; 389 qdisc->q.qlen = 0; 390 } 391 392 static int pfifo_fast_dump(struct Qdisc *qdisc, struct sk_buff *skb) 393 { 394 struct tc_prio_qopt opt = { .bands = PFIFO_FAST_BANDS }; 395 396 memcpy(&opt.priomap, prio2band, TC_PRIO_MAX+1); 397 RTA_PUT(skb, TCA_OPTIONS, sizeof(opt), &opt); 398 return skb->len; 399 400 rtattr_failure: 401 return -1; 402 } 403 404 static int pfifo_fast_init(struct Qdisc *qdisc, struct rtattr *opt) 405 { 406 int prio; 407 struct sk_buff_head *list = qdisc_priv(qdisc); 408 409 for (prio = 0; prio < PFIFO_FAST_BANDS; prio++) 410 skb_queue_head_init(list + prio); 411 412 return 0; 413 } 414 415 static struct Qdisc_ops pfifo_fast_ops = { 416 .id = "pfifo_fast", 417 .priv_size = PFIFO_FAST_BANDS * sizeof(struct sk_buff_head), 418 .enqueue = pfifo_fast_enqueue, 419 .dequeue = pfifo_fast_dequeue, 420 .requeue = pfifo_fast_requeue, 421 .init = pfifo_fast_init, 422 .reset = pfifo_fast_reset, 423 .dump = pfifo_fast_dump, 424 .owner = THIS_MODULE, 425 }; 426 427 struct Qdisc *qdisc_alloc(struct net_device *dev, struct Qdisc_ops *ops) 428 { 429 void *p; 430 struct Qdisc *sch; 431 unsigned int size; 432 int err = -ENOBUFS; 433 434 /* ensure that the Qdisc and the private data are 32-byte aligned */ 435 size = QDISC_ALIGN(sizeof(*sch)); 436 size += ops->priv_size + (QDISC_ALIGNTO - 1); 437 438 p = kzalloc(size, GFP_KERNEL); 439 if (!p) 440 goto errout; 441 sch = (struct Qdisc *) QDISC_ALIGN((unsigned long) p); 442 sch->padded = (char *) sch - (char *) p; 443 444 INIT_LIST_HEAD(&sch->list); 445 skb_queue_head_init(&sch->q); 446 sch->ops = ops; 447 sch->enqueue = ops->enqueue; 448 sch->dequeue = ops->dequeue; 449 sch->dev = dev; 450 dev_hold(dev); 451 atomic_set(&sch->refcnt, 1); 452 453 return sch; 454 errout: 455 return ERR_PTR(-err); 456 } 457 458 struct Qdisc * qdisc_create_dflt(struct net_device *dev, struct Qdisc_ops *ops, 459 unsigned int parentid) 460 { 461 struct Qdisc *sch; 462 463 sch = qdisc_alloc(dev, ops); 464 if (IS_ERR(sch)) 465 goto errout; 466 sch->stats_lock = &dev->queue_lock; 467 sch->parent = parentid; 468 469 if (!ops->init || ops->init(sch, NULL) == 0) 470 return sch; 471 472 qdisc_destroy(sch); 473 errout: 474 return NULL; 475 } 476 477 /* Under dev->queue_lock and BH! */ 478 479 void qdisc_reset(struct Qdisc *qdisc) 480 { 481 struct Qdisc_ops *ops = qdisc->ops; 482 483 if (ops->reset) 484 ops->reset(qdisc); 485 } 486 487 /* this is the rcu callback function to clean up a qdisc when there 488 * are no further references to it */ 489 490 static void __qdisc_destroy(struct rcu_head *head) 491 { 492 struct Qdisc *qdisc = container_of(head, struct Qdisc, q_rcu); 493 kfree((char *) qdisc - qdisc->padded); 494 } 495 496 /* Under dev->queue_lock and BH! */ 497 498 void qdisc_destroy(struct Qdisc *qdisc) 499 { 500 struct Qdisc_ops *ops = qdisc->ops; 501 502 if (qdisc->flags & TCQ_F_BUILTIN || 503 !atomic_dec_and_test(&qdisc->refcnt)) 504 return; 505 506 list_del(&qdisc->list); 507 gen_kill_estimator(&qdisc->bstats, &qdisc->rate_est); 508 if (ops->reset) 509 ops->reset(qdisc); 510 if (ops->destroy) 511 ops->destroy(qdisc); 512 513 module_put(ops->owner); 514 dev_put(qdisc->dev); 515 call_rcu(&qdisc->q_rcu, __qdisc_destroy); 516 } 517 518 void dev_activate(struct net_device *dev) 519 { 520 /* No queueing discipline is attached to device; 521 create default one i.e. pfifo_fast for devices, 522 which need queueing and noqueue_qdisc for 523 virtual interfaces 524 */ 525 526 if (dev->qdisc_sleeping == &noop_qdisc) { 527 struct Qdisc *qdisc; 528 if (dev->tx_queue_len) { 529 qdisc = qdisc_create_dflt(dev, &pfifo_fast_ops, 530 TC_H_ROOT); 531 if (qdisc == NULL) { 532 printk(KERN_INFO "%s: activation failed\n", dev->name); 533 return; 534 } 535 list_add_tail(&qdisc->list, &dev->qdisc_list); 536 } else { 537 qdisc = &noqueue_qdisc; 538 } 539 dev->qdisc_sleeping = qdisc; 540 } 541 542 if (!netif_carrier_ok(dev)) 543 /* Delay activation until next carrier-on event */ 544 return; 545 546 spin_lock_bh(&dev->queue_lock); 547 rcu_assign_pointer(dev->qdisc, dev->qdisc_sleeping); 548 if (dev->qdisc != &noqueue_qdisc) { 549 dev->trans_start = jiffies; 550 dev_watchdog_up(dev); 551 } 552 spin_unlock_bh(&dev->queue_lock); 553 } 554 555 void dev_deactivate(struct net_device *dev) 556 { 557 struct Qdisc *qdisc; 558 struct sk_buff *skb; 559 560 spin_lock_bh(&dev->queue_lock); 561 qdisc = dev->qdisc; 562 dev->qdisc = &noop_qdisc; 563 564 qdisc_reset(qdisc); 565 566 skb = dev->gso_skb; 567 dev->gso_skb = NULL; 568 spin_unlock_bh(&dev->queue_lock); 569 570 kfree_skb(skb); 571 572 dev_watchdog_down(dev); 573 574 /* Wait for outstanding dev_queue_xmit calls. */ 575 synchronize_rcu(); 576 577 /* Wait for outstanding qdisc_run calls. */ 578 while (test_bit(__LINK_STATE_QDISC_RUNNING, &dev->state)) 579 yield(); 580 } 581 582 void dev_init_scheduler(struct net_device *dev) 583 { 584 qdisc_lock_tree(dev); 585 dev->qdisc = &noop_qdisc; 586 dev->qdisc_sleeping = &noop_qdisc; 587 INIT_LIST_HEAD(&dev->qdisc_list); 588 qdisc_unlock_tree(dev); 589 590 dev_watchdog_init(dev); 591 } 592 593 void dev_shutdown(struct net_device *dev) 594 { 595 struct Qdisc *qdisc; 596 597 qdisc_lock_tree(dev); 598 qdisc = dev->qdisc_sleeping; 599 dev->qdisc = &noop_qdisc; 600 dev->qdisc_sleeping = &noop_qdisc; 601 qdisc_destroy(qdisc); 602 #if defined(CONFIG_NET_SCH_INGRESS) || defined(CONFIG_NET_SCH_INGRESS_MODULE) 603 if ((qdisc = dev->qdisc_ingress) != NULL) { 604 dev->qdisc_ingress = NULL; 605 qdisc_destroy(qdisc); 606 } 607 #endif 608 BUG_TRAP(!timer_pending(&dev->watchdog_timer)); 609 qdisc_unlock_tree(dev); 610 } 611 612 EXPORT_SYMBOL(netif_carrier_on); 613 EXPORT_SYMBOL(netif_carrier_off); 614 EXPORT_SYMBOL(noop_qdisc); 615 EXPORT_SYMBOL(qdisc_create_dflt); 616 EXPORT_SYMBOL(qdisc_destroy); 617 EXPORT_SYMBOL(qdisc_reset); 618 EXPORT_SYMBOL(qdisc_lock_tree); 619 EXPORT_SYMBOL(qdisc_unlock_tree); 620