2 * net/sched/sch_generic.c Generic packet scheduler routines.
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.
9 * Authors: Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
10 * Jamal Hadi Salim, <hadi@cyberus.ca> 990601
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>
23 #include <linux/socket.h>
24 #include <linux/sockios.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>
35 #include <net/pkt_sched.h>
37 /* Main transmission queue. */
39 /* Modifications to data participating in scheduling must be protected with
40 * dev->queue_lock spinlock.
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.
50 void qdisc_lock_tree(struct net_device *dev)
52 spin_lock_bh(&dev->queue_lock);
53 spin_lock(&dev->ingress_lock);
56 void qdisc_unlock_tree(struct net_device *dev)
58 spin_unlock(&dev->ingress_lock);
59 spin_unlock_bh(&dev->queue_lock);
63 dev->queue_lock serializes queue accesses for this device
64 AND dev->qdisc pointer itself.
66 netif_tx_lock serializes accesses to device driver.
68 dev->queue_lock and netif_tx_lock are mutually exclusive,
69 if one is grabbed, another must be free.
75 Returns: 0 - queue is empty or throttled.
76 >0 - queue is not empty.
78 NOTE: Called under dev->queue_lock with locally disabled BH.
81 static inline int qdisc_restart(struct net_device *dev)
83 struct Qdisc *q = dev->qdisc;
87 if (((skb = dev->gso_skb)) || ((skb = q->dequeue(q)))) {
88 unsigned nolock = (dev->features & NETIF_F_LLTX);
93 * When the driver has LLTX set it does its own locking
94 * in start_xmit. No need to add additional overhead by
95 * locking again. These checks are worth it because
96 * even uncongested locks can be quite expensive.
97 * The driver can do trylock like here too, in case
98 * of lock congestion it should return -1 and the packet
102 if (!netif_tx_trylock(dev)) {
104 /* So, someone grabbed the driver. */
106 /* It may be transient configuration error,
107 when hard_start_xmit() recurses. We detect
108 it by checking xmit owner and drop the
109 packet when deadloop is detected.
111 if (dev->xmit_lock_owner == smp_processor_id()) {
114 printk(KERN_DEBUG "Dead loop on netdevice %s, fix it urgently!\n", dev->name);
117 __get_cpu_var(netdev_rx_stat).cpu_collision++;
123 /* And release queue */
124 spin_unlock(&dev->queue_lock);
126 if (!netif_queue_stopped(dev)) {
129 ret = dev_hard_start_xmit(skb, dev);
130 if (ret == NETDEV_TX_OK) {
132 netif_tx_unlock(dev);
134 spin_lock(&dev->queue_lock);
138 if (ret == NETDEV_TX_LOCKED && nolock) {
139 spin_lock(&dev->queue_lock);
145 /* NETDEV_TX_BUSY - we need to requeue */
146 /* Release the driver */
148 netif_tx_unlock(dev);
150 spin_lock(&dev->queue_lock);
154 /* Device kicked us out :(
155 This is possible in three cases:
158 1. fastroute is enabled
159 2. device cannot determine busy state
160 before start of transmission (f.e. dialout)
161 3. device is buggy (ppp)
165 if (unlikely(q == &noop_qdisc))
170 q->ops->requeue(skb, q);
176 BUG_ON((int) q->q.qlen < 0);
180 void __qdisc_run(struct net_device *dev)
183 if (!qdisc_restart(dev))
185 } while (!netif_queue_stopped(dev));
187 clear_bit(__LINK_STATE_QDISC_RUNNING, &dev->state);
190 static void dev_watchdog(unsigned long arg)
192 struct net_device *dev = (struct net_device *)arg;
195 if (dev->qdisc != &noop_qdisc) {
196 if (netif_device_present(dev) &&
197 netif_running(dev) &&
198 netif_carrier_ok(dev)) {
199 if (netif_queue_stopped(dev) &&
200 time_after(jiffies, dev->trans_start + dev->watchdog_timeo)) {
202 printk(KERN_INFO "NETDEV WATCHDOG: %s: transmit timed out\n",
204 dev->tx_timeout(dev);
206 if (!mod_timer(&dev->watchdog_timer, round_jiffies(jiffies + dev->watchdog_timeo)))
210 netif_tx_unlock(dev);
215 static void dev_watchdog_init(struct net_device *dev)
217 init_timer(&dev->watchdog_timer);
218 dev->watchdog_timer.data = (unsigned long)dev;
219 dev->watchdog_timer.function = dev_watchdog;
222 void __netdev_watchdog_up(struct net_device *dev)
224 if (dev->tx_timeout) {
225 if (dev->watchdog_timeo <= 0)
226 dev->watchdog_timeo = 5*HZ;
227 if (!mod_timer(&dev->watchdog_timer,
228 round_jiffies(jiffies + dev->watchdog_timeo)))
233 static void dev_watchdog_up(struct net_device *dev)
235 __netdev_watchdog_up(dev);
238 static void dev_watchdog_down(struct net_device *dev)
240 netif_tx_lock_bh(dev);
241 if (del_timer(&dev->watchdog_timer))
243 netif_tx_unlock_bh(dev);
246 void netif_carrier_on(struct net_device *dev)
248 if (test_and_clear_bit(__LINK_STATE_NOCARRIER, &dev->state))
249 linkwatch_fire_event(dev);
250 if (netif_running(dev))
251 __netdev_watchdog_up(dev);
254 void netif_carrier_off(struct net_device *dev)
256 if (!test_and_set_bit(__LINK_STATE_NOCARRIER, &dev->state))
257 linkwatch_fire_event(dev);
260 /* "NOOP" scheduler: the best scheduler, recommended for all interfaces
261 under all circumstances. It is difficult to invent anything faster or
265 static int noop_enqueue(struct sk_buff *skb, struct Qdisc * qdisc)
271 static struct sk_buff *noop_dequeue(struct Qdisc * qdisc)
276 static int noop_requeue(struct sk_buff *skb, struct Qdisc* qdisc)
279 printk(KERN_DEBUG "%s deferred output. It is buggy.\n",
285 struct Qdisc_ops noop_qdisc_ops = {
288 .enqueue = noop_enqueue,
289 .dequeue = noop_dequeue,
290 .requeue = noop_requeue,
291 .owner = THIS_MODULE,
294 struct Qdisc noop_qdisc = {
295 .enqueue = noop_enqueue,
296 .dequeue = noop_dequeue,
297 .flags = TCQ_F_BUILTIN,
298 .ops = &noop_qdisc_ops,
299 .list = LIST_HEAD_INIT(noop_qdisc.list),
302 static struct Qdisc_ops noqueue_qdisc_ops = {
305 .enqueue = noop_enqueue,
306 .dequeue = noop_dequeue,
307 .requeue = noop_requeue,
308 .owner = THIS_MODULE,
311 static struct Qdisc noqueue_qdisc = {
313 .dequeue = noop_dequeue,
314 .flags = TCQ_F_BUILTIN,
315 .ops = &noqueue_qdisc_ops,
316 .list = LIST_HEAD_INIT(noqueue_qdisc.list),
320 static const u8 prio2band[TC_PRIO_MAX+1] =
321 { 1, 2, 2, 2, 1, 2, 0, 0 , 1, 1, 1, 1, 1, 1, 1, 1 };
323 /* 3-band FIFO queue: old style, but should be a bit faster than
324 generic prio+fifo combination.
327 #define PFIFO_FAST_BANDS 3
329 static inline struct sk_buff_head *prio2list(struct sk_buff *skb,
332 struct sk_buff_head *list = qdisc_priv(qdisc);
333 return list + prio2band[skb->priority & TC_PRIO_MAX];
336 static int pfifo_fast_enqueue(struct sk_buff *skb, struct Qdisc* qdisc)
338 struct sk_buff_head *list = prio2list(skb, qdisc);
340 if (skb_queue_len(list) < qdisc->dev->tx_queue_len) {
342 return __qdisc_enqueue_tail(skb, qdisc, list);
345 return qdisc_drop(skb, qdisc);
348 static struct sk_buff *pfifo_fast_dequeue(struct Qdisc* qdisc)
351 struct sk_buff_head *list = qdisc_priv(qdisc);
353 for (prio = 0; prio < PFIFO_FAST_BANDS; prio++) {
354 if (!skb_queue_empty(list + prio)) {
356 return __qdisc_dequeue_head(qdisc, list + prio);
363 static int pfifo_fast_requeue(struct sk_buff *skb, struct Qdisc* qdisc)
366 return __qdisc_requeue(skb, qdisc, prio2list(skb, qdisc));
369 static void pfifo_fast_reset(struct Qdisc* qdisc)
372 struct sk_buff_head *list = qdisc_priv(qdisc);
374 for (prio = 0; prio < PFIFO_FAST_BANDS; prio++)
375 __qdisc_reset_queue(qdisc, list + prio);
377 qdisc->qstats.backlog = 0;
381 static int pfifo_fast_dump(struct Qdisc *qdisc, struct sk_buff *skb)
383 struct tc_prio_qopt opt = { .bands = PFIFO_FAST_BANDS };
385 memcpy(&opt.priomap, prio2band, TC_PRIO_MAX+1);
386 RTA_PUT(skb, TCA_OPTIONS, sizeof(opt), &opt);
393 static int pfifo_fast_init(struct Qdisc *qdisc, struct rtattr *opt)
396 struct sk_buff_head *list = qdisc_priv(qdisc);
398 for (prio = 0; prio < PFIFO_FAST_BANDS; prio++)
399 skb_queue_head_init(list + prio);
404 static struct Qdisc_ops pfifo_fast_ops = {
406 .priv_size = PFIFO_FAST_BANDS * sizeof(struct sk_buff_head),
407 .enqueue = pfifo_fast_enqueue,
408 .dequeue = pfifo_fast_dequeue,
409 .requeue = pfifo_fast_requeue,
410 .init = pfifo_fast_init,
411 .reset = pfifo_fast_reset,
412 .dump = pfifo_fast_dump,
413 .owner = THIS_MODULE,
416 struct Qdisc *qdisc_alloc(struct net_device *dev, struct Qdisc_ops *ops)
423 /* ensure that the Qdisc and the private data are 32-byte aligned */
424 size = QDISC_ALIGN(sizeof(*sch));
425 size += ops->priv_size + (QDISC_ALIGNTO - 1);
427 p = kzalloc(size, GFP_KERNEL);
430 sch = (struct Qdisc *) QDISC_ALIGN((unsigned long) p);
431 sch->padded = (char *) sch - (char *) p;
433 INIT_LIST_HEAD(&sch->list);
434 skb_queue_head_init(&sch->q);
436 sch->enqueue = ops->enqueue;
437 sch->dequeue = ops->dequeue;
440 atomic_set(&sch->refcnt, 1);
444 return ERR_PTR(-err);
447 struct Qdisc * qdisc_create_dflt(struct net_device *dev, struct Qdisc_ops *ops,
448 unsigned int parentid)
452 sch = qdisc_alloc(dev, ops);
455 sch->stats_lock = &dev->queue_lock;
456 sch->parent = parentid;
458 if (!ops->init || ops->init(sch, NULL) == 0)
466 /* Under dev->queue_lock and BH! */
468 void qdisc_reset(struct Qdisc *qdisc)
470 struct Qdisc_ops *ops = qdisc->ops;
476 /* this is the rcu callback function to clean up a qdisc when there
477 * are no further references to it */
479 static void __qdisc_destroy(struct rcu_head *head)
481 struct Qdisc *qdisc = container_of(head, struct Qdisc, q_rcu);
482 kfree((char *) qdisc - qdisc->padded);
485 /* Under dev->queue_lock and BH! */
487 void qdisc_destroy(struct Qdisc *qdisc)
489 struct Qdisc_ops *ops = qdisc->ops;
491 if (qdisc->flags & TCQ_F_BUILTIN ||
492 !atomic_dec_and_test(&qdisc->refcnt))
495 list_del(&qdisc->list);
496 #ifdef CONFIG_NET_ESTIMATOR
497 gen_kill_estimator(&qdisc->bstats, &qdisc->rate_est);
504 module_put(ops->owner);
506 call_rcu(&qdisc->q_rcu, __qdisc_destroy);
509 void dev_activate(struct net_device *dev)
511 /* No queueing discipline is attached to device;
512 create default one i.e. pfifo_fast for devices,
513 which need queueing and noqueue_qdisc for
517 if (dev->qdisc_sleeping == &noop_qdisc) {
519 if (dev->tx_queue_len) {
520 qdisc = qdisc_create_dflt(dev, &pfifo_fast_ops,
523 printk(KERN_INFO "%s: activation failed\n", dev->name);
526 list_add_tail(&qdisc->list, &dev->qdisc_list);
528 qdisc = &noqueue_qdisc;
530 dev->qdisc_sleeping = qdisc;
533 if (!netif_carrier_ok(dev))
534 /* Delay activation until next carrier-on event */
537 spin_lock_bh(&dev->queue_lock);
538 rcu_assign_pointer(dev->qdisc, dev->qdisc_sleeping);
539 if (dev->qdisc != &noqueue_qdisc) {
540 dev->trans_start = jiffies;
541 dev_watchdog_up(dev);
543 spin_unlock_bh(&dev->queue_lock);
546 void dev_deactivate(struct net_device *dev)
551 spin_lock_bh(&dev->queue_lock);
553 dev->qdisc = &noop_qdisc;
559 spin_unlock_bh(&dev->queue_lock);
563 dev_watchdog_down(dev);
565 /* Wait for outstanding dev_queue_xmit calls. */
568 /* Wait for outstanding qdisc_run calls. */
569 while (test_bit(__LINK_STATE_QDISC_RUNNING, &dev->state))
573 void dev_init_scheduler(struct net_device *dev)
575 qdisc_lock_tree(dev);
576 dev->qdisc = &noop_qdisc;
577 dev->qdisc_sleeping = &noop_qdisc;
578 INIT_LIST_HEAD(&dev->qdisc_list);
579 qdisc_unlock_tree(dev);
581 dev_watchdog_init(dev);
584 void dev_shutdown(struct net_device *dev)
588 qdisc_lock_tree(dev);
589 qdisc = dev->qdisc_sleeping;
590 dev->qdisc = &noop_qdisc;
591 dev->qdisc_sleeping = &noop_qdisc;
592 qdisc_destroy(qdisc);
593 #if defined(CONFIG_NET_SCH_INGRESS) || defined(CONFIG_NET_SCH_INGRESS_MODULE)
594 if ((qdisc = dev->qdisc_ingress) != NULL) {
595 dev->qdisc_ingress = NULL;
596 qdisc_destroy(qdisc);
599 BUG_TRAP(!timer_pending(&dev->watchdog_timer));
600 qdisc_unlock_tree(dev);
603 EXPORT_SYMBOL(netif_carrier_on);
604 EXPORT_SYMBOL(netif_carrier_off);
605 EXPORT_SYMBOL(noop_qdisc);
606 EXPORT_SYMBOL(qdisc_create_dflt);
607 EXPORT_SYMBOL(qdisc_destroy);
608 EXPORT_SYMBOL(qdisc_reset);
609 EXPORT_SYMBOL(qdisc_lock_tree);
610 EXPORT_SYMBOL(qdisc_unlock_tree);