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 <asm/uaccess.h> 15 #include <asm/system.h> 16 #include <linux/bitops.h> 17 #include <linux/module.h> 18 #include <linux/types.h> 19 #include <linux/kernel.h> 20 #include <linux/sched.h> 21 #include <linux/string.h> 22 #include <linux/mm.h> 23 #include <linux/socket.h> 24 #include <linux/sockios.h> 25 #include <linux/in.h> 26 #include <linux/errno.h> 27 #include <linux/interrupt.h> 28 #include <linux/netdevice.h> 29 #include <linux/skbuff.h> 30 #include <linux/rtnetlink.h> 31 #include <linux/init.h> 32 #include <linux/rcupdate.h> 33 #include <linux/list.h> 34 #include <net/sock.h> 35 #include <net/pkt_sched.h> 36 37 /* Main transmission queue. */ 38 39 /* Modifications to data participating in scheduling must be protected with 40 * dev->queue_lock spinlock. 41 * 42 * The idea is the following: 43 * - enqueue, dequeue are serialized via top level device 44 * spinlock dev->queue_lock. 45 * - ingress filtering is serialized via top level device 46 * spinlock dev->ingress_lock. 47 * - updates to tree and tree walking are only done under the rtnl mutex. 48 */ 49 50 void qdisc_lock_tree(struct net_device *dev) 51 { 52 spin_lock_bh(&dev->queue_lock); 53 spin_lock(&dev->ingress_lock); 54 } 55 56 void qdisc_unlock_tree(struct net_device *dev) 57 { 58 spin_unlock(&dev->ingress_lock); 59 spin_unlock_bh(&dev->queue_lock); 60 } 61 62 static inline int qdisc_qlen(struct Qdisc *q) 63 { 64 BUG_ON((int) q->q.qlen < 0); 65 return q->q.qlen; 66 } 67 68 static inline int dev_requeue_skb(struct sk_buff *skb, struct net_device *dev, 69 struct Qdisc *q) 70 { 71 if (unlikely(skb->next)) 72 dev->gso_skb = skb; 73 else 74 q->ops->requeue(skb, q); 75 76 netif_schedule(dev); 77 return 0; 78 } 79 80 static inline struct sk_buff *dev_dequeue_skb(struct net_device *dev, 81 struct Qdisc *q) 82 { 83 struct sk_buff *skb; 84 85 if ((skb = dev->gso_skb)) 86 dev->gso_skb = NULL; 87 else 88 skb = q->dequeue(q); 89 90 return skb; 91 } 92 93 static inline int handle_dev_cpu_collision(struct sk_buff *skb, 94 struct net_device *dev, 95 struct Qdisc *q) 96 { 97 int ret; 98 99 if (unlikely(dev->xmit_lock_owner == smp_processor_id())) { 100 /* 101 * Same CPU holding the lock. It may be a transient 102 * configuration error, when hard_start_xmit() recurses. We 103 * detect it by checking xmit owner and drop the packet when 104 * deadloop is detected. Return OK to try the next skb. 105 */ 106 kfree_skb(skb); 107 if (net_ratelimit()) 108 printk(KERN_WARNING "Dead loop on netdevice %s, " 109 "fix it urgently!\n", dev->name); 110 ret = qdisc_qlen(q); 111 } else { 112 /* 113 * Another cpu is holding lock, requeue & delay xmits for 114 * some time. 115 */ 116 __get_cpu_var(netdev_rx_stat).cpu_collision++; 117 ret = dev_requeue_skb(skb, dev, q); 118 } 119 120 return ret; 121 } 122 123 /* 124 * NOTE: Called under dev->queue_lock with locally disabled BH. 125 * 126 * __LINK_STATE_QDISC_RUNNING guarantees only one CPU can process this 127 * device at a time. dev->queue_lock serializes queue accesses for 128 * this device AND dev->qdisc pointer itself. 129 * 130 * netif_tx_lock serializes accesses to device driver. 131 * 132 * dev->queue_lock and netif_tx_lock are mutually exclusive, 133 * if one is grabbed, another must be free. 134 * 135 * Note, that this procedure can be called by a watchdog timer 136 * 137 * Returns to the caller: 138 * 0 - queue is empty or throttled. 139 * >0 - queue is not empty. 140 * 141 */ 142 static inline int qdisc_restart(struct net_device *dev) 143 { 144 struct Qdisc *q = dev->qdisc; 145 struct sk_buff *skb; 146 unsigned lockless; 147 int ret; 148 149 /* Dequeue packet */ 150 if (unlikely((skb = dev_dequeue_skb(dev, q)) == NULL)) 151 return 0; 152 153 /* 154 * When the driver has LLTX set, it does its own locking in 155 * start_xmit. These checks are worth it because even uncongested 156 * locks can be quite expensive. The driver can do a trylock, as 157 * is being done here; in case of lock contention it should return 158 * NETDEV_TX_LOCKED and the packet will be requeued. 159 */ 160 lockless = (dev->features & NETIF_F_LLTX); 161 162 if (!lockless && !netif_tx_trylock(dev)) { 163 /* Another CPU grabbed the driver tx lock */ 164 return handle_dev_cpu_collision(skb, dev, q); 165 } 166 167 /* And release queue */ 168 spin_unlock(&dev->queue_lock); 169 170 ret = NETDEV_TX_BUSY; 171 if (!netif_queue_stopped(dev)) 172 ret = dev_hard_start_xmit(skb, dev); 173 174 if (!lockless) 175 netif_tx_unlock(dev); 176 177 spin_lock(&dev->queue_lock); 178 q = dev->qdisc; 179 180 switch (ret) { 181 case NETDEV_TX_OK: 182 /* Driver sent out skb successfully */ 183 ret = qdisc_qlen(q); 184 break; 185 186 case NETDEV_TX_LOCKED: 187 /* Driver try lock failed */ 188 ret = handle_dev_cpu_collision(skb, dev, q); 189 break; 190 191 default: 192 /* Driver returned NETDEV_TX_BUSY - requeue skb */ 193 if (unlikely (ret != NETDEV_TX_BUSY && net_ratelimit())) 194 printk(KERN_WARNING "BUG %s code %d qlen %d\n", 195 dev->name, ret, q->q.qlen); 196 197 ret = dev_requeue_skb(skb, dev, q); 198 break; 199 } 200 201 return ret; 202 } 203 204 void __qdisc_run(struct net_device *dev) 205 { 206 do { 207 if (!qdisc_restart(dev)) 208 break; 209 } while (!netif_queue_stopped(dev)); 210 211 clear_bit(__LINK_STATE_QDISC_RUNNING, &dev->state); 212 } 213 214 static void dev_watchdog(unsigned long arg) 215 { 216 struct net_device *dev = (struct net_device *)arg; 217 218 netif_tx_lock(dev); 219 if (dev->qdisc != &noop_qdisc) { 220 if (netif_device_present(dev) && 221 netif_running(dev) && 222 netif_carrier_ok(dev)) { 223 if (netif_queue_stopped(dev) && 224 time_after(jiffies, dev->trans_start + dev->watchdog_timeo)) { 225 226 printk(KERN_INFO "NETDEV WATCHDOG: %s: transmit timed out\n", 227 dev->name); 228 dev->tx_timeout(dev); 229 } 230 if (!mod_timer(&dev->watchdog_timer, round_jiffies(jiffies + dev->watchdog_timeo))) 231 dev_hold(dev); 232 } 233 } 234 netif_tx_unlock(dev); 235 236 dev_put(dev); 237 } 238 239 static void dev_watchdog_init(struct net_device *dev) 240 { 241 init_timer(&dev->watchdog_timer); 242 dev->watchdog_timer.data = (unsigned long)dev; 243 dev->watchdog_timer.function = dev_watchdog; 244 } 245 246 void __netdev_watchdog_up(struct net_device *dev) 247 { 248 if (dev->tx_timeout) { 249 if (dev->watchdog_timeo <= 0) 250 dev->watchdog_timeo = 5*HZ; 251 if (!mod_timer(&dev->watchdog_timer, 252 round_jiffies(jiffies + dev->watchdog_timeo))) 253 dev_hold(dev); 254 } 255 } 256 257 static void dev_watchdog_up(struct net_device *dev) 258 { 259 __netdev_watchdog_up(dev); 260 } 261 262 static void dev_watchdog_down(struct net_device *dev) 263 { 264 netif_tx_lock_bh(dev); 265 if (del_timer(&dev->watchdog_timer)) 266 dev_put(dev); 267 netif_tx_unlock_bh(dev); 268 } 269 270 void netif_carrier_on(struct net_device *dev) 271 { 272 if (test_and_clear_bit(__LINK_STATE_NOCARRIER, &dev->state)) 273 linkwatch_fire_event(dev); 274 if (netif_running(dev)) 275 __netdev_watchdog_up(dev); 276 } 277 278 void netif_carrier_off(struct net_device *dev) 279 { 280 if (!test_and_set_bit(__LINK_STATE_NOCARRIER, &dev->state)) 281 linkwatch_fire_event(dev); 282 } 283 284 /* "NOOP" scheduler: the best scheduler, recommended for all interfaces 285 under all circumstances. It is difficult to invent anything faster or 286 cheaper. 287 */ 288 289 static int noop_enqueue(struct sk_buff *skb, struct Qdisc * qdisc) 290 { 291 kfree_skb(skb); 292 return NET_XMIT_CN; 293 } 294 295 static struct sk_buff *noop_dequeue(struct Qdisc * qdisc) 296 { 297 return NULL; 298 } 299 300 static int noop_requeue(struct sk_buff *skb, struct Qdisc* qdisc) 301 { 302 if (net_ratelimit()) 303 printk(KERN_DEBUG "%s deferred output. It is buggy.\n", 304 skb->dev->name); 305 kfree_skb(skb); 306 return NET_XMIT_CN; 307 } 308 309 struct Qdisc_ops noop_qdisc_ops = { 310 .id = "noop", 311 .priv_size = 0, 312 .enqueue = noop_enqueue, 313 .dequeue = noop_dequeue, 314 .requeue = noop_requeue, 315 .owner = THIS_MODULE, 316 }; 317 318 struct Qdisc noop_qdisc = { 319 .enqueue = noop_enqueue, 320 .dequeue = noop_dequeue, 321 .flags = TCQ_F_BUILTIN, 322 .ops = &noop_qdisc_ops, 323 .list = LIST_HEAD_INIT(noop_qdisc.list), 324 }; 325 326 static struct Qdisc_ops noqueue_qdisc_ops = { 327 .id = "noqueue", 328 .priv_size = 0, 329 .enqueue = noop_enqueue, 330 .dequeue = noop_dequeue, 331 .requeue = noop_requeue, 332 .owner = THIS_MODULE, 333 }; 334 335 static struct Qdisc noqueue_qdisc = { 336 .enqueue = NULL, 337 .dequeue = noop_dequeue, 338 .flags = TCQ_F_BUILTIN, 339 .ops = &noqueue_qdisc_ops, 340 .list = LIST_HEAD_INIT(noqueue_qdisc.list), 341 }; 342 343 344 static const u8 prio2band[TC_PRIO_MAX+1] = 345 { 1, 2, 2, 2, 1, 2, 0, 0 , 1, 1, 1, 1, 1, 1, 1, 1 }; 346 347 /* 3-band FIFO queue: old style, but should be a bit faster than 348 generic prio+fifo combination. 349 */ 350 351 #define PFIFO_FAST_BANDS 3 352 353 static inline struct sk_buff_head *prio2list(struct sk_buff *skb, 354 struct Qdisc *qdisc) 355 { 356 struct sk_buff_head *list = qdisc_priv(qdisc); 357 return list + prio2band[skb->priority & TC_PRIO_MAX]; 358 } 359 360 static int pfifo_fast_enqueue(struct sk_buff *skb, struct Qdisc* qdisc) 361 { 362 struct sk_buff_head *list = prio2list(skb, qdisc); 363 364 if (skb_queue_len(list) < qdisc->dev->tx_queue_len) { 365 qdisc->q.qlen++; 366 return __qdisc_enqueue_tail(skb, qdisc, list); 367 } 368 369 return qdisc_drop(skb, qdisc); 370 } 371 372 static struct sk_buff *pfifo_fast_dequeue(struct Qdisc* qdisc) 373 { 374 int prio; 375 struct sk_buff_head *list = qdisc_priv(qdisc); 376 377 for (prio = 0; prio < PFIFO_FAST_BANDS; prio++) { 378 if (!skb_queue_empty(list + prio)) { 379 qdisc->q.qlen--; 380 return __qdisc_dequeue_head(qdisc, list + prio); 381 } 382 } 383 384 return NULL; 385 } 386 387 static int pfifo_fast_requeue(struct sk_buff *skb, struct Qdisc* qdisc) 388 { 389 qdisc->q.qlen++; 390 return __qdisc_requeue(skb, qdisc, prio2list(skb, qdisc)); 391 } 392 393 static void pfifo_fast_reset(struct Qdisc* qdisc) 394 { 395 int prio; 396 struct sk_buff_head *list = qdisc_priv(qdisc); 397 398 for (prio = 0; prio < PFIFO_FAST_BANDS; prio++) 399 __qdisc_reset_queue(qdisc, list + prio); 400 401 qdisc->qstats.backlog = 0; 402 qdisc->q.qlen = 0; 403 } 404 405 static int pfifo_fast_dump(struct Qdisc *qdisc, struct sk_buff *skb) 406 { 407 struct tc_prio_qopt opt = { .bands = PFIFO_FAST_BANDS }; 408 409 memcpy(&opt.priomap, prio2band, TC_PRIO_MAX+1); 410 RTA_PUT(skb, TCA_OPTIONS, sizeof(opt), &opt); 411 return skb->len; 412 413 rtattr_failure: 414 return -1; 415 } 416 417 static int pfifo_fast_init(struct Qdisc *qdisc, struct rtattr *opt) 418 { 419 int prio; 420 struct sk_buff_head *list = qdisc_priv(qdisc); 421 422 for (prio = 0; prio < PFIFO_FAST_BANDS; prio++) 423 skb_queue_head_init(list + prio); 424 425 return 0; 426 } 427 428 static struct Qdisc_ops pfifo_fast_ops = { 429 .id = "pfifo_fast", 430 .priv_size = PFIFO_FAST_BANDS * sizeof(struct sk_buff_head), 431 .enqueue = pfifo_fast_enqueue, 432 .dequeue = pfifo_fast_dequeue, 433 .requeue = pfifo_fast_requeue, 434 .init = pfifo_fast_init, 435 .reset = pfifo_fast_reset, 436 .dump = pfifo_fast_dump, 437 .owner = THIS_MODULE, 438 }; 439 440 struct Qdisc *qdisc_alloc(struct net_device *dev, struct Qdisc_ops *ops) 441 { 442 void *p; 443 struct Qdisc *sch; 444 unsigned int size; 445 int err = -ENOBUFS; 446 447 /* ensure that the Qdisc and the private data are 32-byte aligned */ 448 size = QDISC_ALIGN(sizeof(*sch)); 449 size += ops->priv_size + (QDISC_ALIGNTO - 1); 450 451 p = kzalloc(size, GFP_KERNEL); 452 if (!p) 453 goto errout; 454 sch = (struct Qdisc *) QDISC_ALIGN((unsigned long) p); 455 sch->padded = (char *) sch - (char *) p; 456 457 INIT_LIST_HEAD(&sch->list); 458 skb_queue_head_init(&sch->q); 459 sch->ops = ops; 460 sch->enqueue = ops->enqueue; 461 sch->dequeue = ops->dequeue; 462 sch->dev = dev; 463 dev_hold(dev); 464 atomic_set(&sch->refcnt, 1); 465 466 return sch; 467 errout: 468 return ERR_PTR(-err); 469 } 470 471 struct Qdisc * qdisc_create_dflt(struct net_device *dev, struct Qdisc_ops *ops, 472 unsigned int parentid) 473 { 474 struct Qdisc *sch; 475 476 sch = qdisc_alloc(dev, ops); 477 if (IS_ERR(sch)) 478 goto errout; 479 sch->stats_lock = &dev->queue_lock; 480 sch->parent = parentid; 481 482 if (!ops->init || ops->init(sch, NULL) == 0) 483 return sch; 484 485 qdisc_destroy(sch); 486 errout: 487 return NULL; 488 } 489 490 /* Under dev->queue_lock and BH! */ 491 492 void qdisc_reset(struct Qdisc *qdisc) 493 { 494 struct Qdisc_ops *ops = qdisc->ops; 495 496 if (ops->reset) 497 ops->reset(qdisc); 498 } 499 500 /* this is the rcu callback function to clean up a qdisc when there 501 * are no further references to it */ 502 503 static void __qdisc_destroy(struct rcu_head *head) 504 { 505 struct Qdisc *qdisc = container_of(head, struct Qdisc, q_rcu); 506 kfree((char *) qdisc - qdisc->padded); 507 } 508 509 /* Under dev->queue_lock and BH! */ 510 511 void qdisc_destroy(struct Qdisc *qdisc) 512 { 513 struct Qdisc_ops *ops = qdisc->ops; 514 515 if (qdisc->flags & TCQ_F_BUILTIN || 516 !atomic_dec_and_test(&qdisc->refcnt)) 517 return; 518 519 list_del(&qdisc->list); 520 #ifdef CONFIG_NET_ESTIMATOR 521 gen_kill_estimator(&qdisc->bstats, &qdisc->rate_est); 522 #endif 523 if (ops->reset) 524 ops->reset(qdisc); 525 if (ops->destroy) 526 ops->destroy(qdisc); 527 528 module_put(ops->owner); 529 dev_put(qdisc->dev); 530 call_rcu(&qdisc->q_rcu, __qdisc_destroy); 531 } 532 533 void dev_activate(struct net_device *dev) 534 { 535 /* No queueing discipline is attached to device; 536 create default one i.e. pfifo_fast for devices, 537 which need queueing and noqueue_qdisc for 538 virtual interfaces 539 */ 540 541 if (dev->qdisc_sleeping == &noop_qdisc) { 542 struct Qdisc *qdisc; 543 if (dev->tx_queue_len) { 544 qdisc = qdisc_create_dflt(dev, &pfifo_fast_ops, 545 TC_H_ROOT); 546 if (qdisc == NULL) { 547 printk(KERN_INFO "%s: activation failed\n", dev->name); 548 return; 549 } 550 list_add_tail(&qdisc->list, &dev->qdisc_list); 551 } else { 552 qdisc = &noqueue_qdisc; 553 } 554 dev->qdisc_sleeping = qdisc; 555 } 556 557 if (!netif_carrier_ok(dev)) 558 /* Delay activation until next carrier-on event */ 559 return; 560 561 spin_lock_bh(&dev->queue_lock); 562 rcu_assign_pointer(dev->qdisc, dev->qdisc_sleeping); 563 if (dev->qdisc != &noqueue_qdisc) { 564 dev->trans_start = jiffies; 565 dev_watchdog_up(dev); 566 } 567 spin_unlock_bh(&dev->queue_lock); 568 } 569 570 void dev_deactivate(struct net_device *dev) 571 { 572 struct Qdisc *qdisc; 573 struct sk_buff *skb; 574 575 spin_lock_bh(&dev->queue_lock); 576 qdisc = dev->qdisc; 577 dev->qdisc = &noop_qdisc; 578 579 qdisc_reset(qdisc); 580 581 skb = dev->gso_skb; 582 dev->gso_skb = NULL; 583 spin_unlock_bh(&dev->queue_lock); 584 585 kfree_skb(skb); 586 587 dev_watchdog_down(dev); 588 589 /* Wait for outstanding dev_queue_xmit calls. */ 590 synchronize_rcu(); 591 592 /* Wait for outstanding qdisc_run calls. */ 593 while (test_bit(__LINK_STATE_QDISC_RUNNING, &dev->state)) 594 yield(); 595 } 596 597 void dev_init_scheduler(struct net_device *dev) 598 { 599 qdisc_lock_tree(dev); 600 dev->qdisc = &noop_qdisc; 601 dev->qdisc_sleeping = &noop_qdisc; 602 INIT_LIST_HEAD(&dev->qdisc_list); 603 qdisc_unlock_tree(dev); 604 605 dev_watchdog_init(dev); 606 } 607 608 void dev_shutdown(struct net_device *dev) 609 { 610 struct Qdisc *qdisc; 611 612 qdisc_lock_tree(dev); 613 qdisc = dev->qdisc_sleeping; 614 dev->qdisc = &noop_qdisc; 615 dev->qdisc_sleeping = &noop_qdisc; 616 qdisc_destroy(qdisc); 617 #if defined(CONFIG_NET_SCH_INGRESS) || defined(CONFIG_NET_SCH_INGRESS_MODULE) 618 if ((qdisc = dev->qdisc_ingress) != NULL) { 619 dev->qdisc_ingress = NULL; 620 qdisc_destroy(qdisc); 621 } 622 #endif 623 BUG_TRAP(!timer_pending(&dev->watchdog_timer)); 624 qdisc_unlock_tree(dev); 625 } 626 627 EXPORT_SYMBOL(netif_carrier_on); 628 EXPORT_SYMBOL(netif_carrier_off); 629 EXPORT_SYMBOL(noop_qdisc); 630 EXPORT_SYMBOL(qdisc_create_dflt); 631 EXPORT_SYMBOL(qdisc_destroy); 632 EXPORT_SYMBOL(qdisc_reset); 633 EXPORT_SYMBOL(qdisc_lock_tree); 634 EXPORT_SYMBOL(qdisc_unlock_tree); 635