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/config.h>
18 #include <linux/module.h>
19 #include <linux/types.h>
20 #include <linux/kernel.h>
21 #include <linux/sched.h>
22 #include <linux/string.h>
24 #include <linux/socket.h>
25 #include <linux/sockios.h>
27 #include <linux/errno.h>
28 #include <linux/interrupt.h>
29 #include <linux/netdevice.h>
30 #include <linux/skbuff.h>
31 #include <linux/rtnetlink.h>
32 #include <linux/init.h>
33 #include <linux/rcupdate.h>
34 #include <linux/list.h>
36 #include <net/pkt_sched.h>
38 /* Main transmission queue. */
40 /* Main qdisc structure lock.
42 However, modifications
43 to data, participating in scheduling must be additionally
44 protected with dev->queue_lock spinlock.
46 The idea is the following:
47 - enqueue, dequeue are serialized via top level device
48 spinlock dev->queue_lock.
49 - tree walking is protected by read_lock_bh(qdisc_tree_lock)
50 and this lock is used only in process context.
51 - updates to tree are made under rtnl semaphore or
52 from softirq context (__qdisc_destroy rcu-callback)
53 hence this lock needs local bh disabling.
55 qdisc_tree_lock must be grabbed BEFORE dev->queue_lock!
57 DEFINE_RWLOCK(qdisc_tree_lock);
59 void qdisc_lock_tree(struct net_device *dev)
61 write_lock_bh(&qdisc_tree_lock);
62 spin_lock_bh(&dev->queue_lock);
65 void qdisc_unlock_tree(struct net_device *dev)
67 spin_unlock_bh(&dev->queue_lock);
68 write_unlock_bh(&qdisc_tree_lock);
72 dev->queue_lock serializes queue accesses for this device
73 AND dev->qdisc pointer itself.
75 dev->xmit_lock serializes accesses to device driver.
77 dev->queue_lock and dev->xmit_lock are mutually exclusive,
78 if one is grabbed, another must be free.
83 Note, that this procedure can be called by a watchdog timer, so that
84 we do not check dev->tbusy flag here.
86 Returns: 0 - queue is empty.
87 >0 - queue is not empty, but throttled.
88 <0 - queue is not empty. Device is throttled, if dev->tbusy != 0.
90 NOTE: Called under dev->queue_lock with locally disabled BH.
93 int qdisc_restart(struct net_device *dev)
95 struct Qdisc *q = dev->qdisc;
99 if ((skb = q->dequeue(q)) != NULL) {
100 unsigned nolock = (dev->features & NETIF_F_LLTX);
102 * When the driver has LLTX set it does its own locking
103 * in start_xmit. No need to add additional overhead by
104 * locking again. These checks are worth it because
105 * even uncongested locks can be quite expensive.
106 * The driver can do trylock like here too, in case
107 * of lock congestion it should return -1 and the packet
111 if (!spin_trylock(&dev->xmit_lock)) {
113 /* So, someone grabbed the driver. */
115 /* It may be transient configuration error,
116 when hard_start_xmit() recurses. We detect
117 it by checking xmit owner and drop the
118 packet when deadloop is detected.
120 if (dev->xmit_lock_owner == smp_processor_id()) {
123 printk(KERN_DEBUG "Dead loop on netdevice %s, fix it urgently!\n", dev->name);
126 __get_cpu_var(netdev_rx_stat).cpu_collision++;
129 /* Remember that the driver is grabbed by us. */
130 dev->xmit_lock_owner = smp_processor_id();
134 /* And release queue */
135 spin_unlock(&dev->queue_lock);
137 if (!netif_queue_stopped(dev)) {
140 dev_queue_xmit_nit(skb, dev);
142 ret = dev->hard_start_xmit(skb, dev);
143 if (ret == NETDEV_TX_OK) {
145 dev->xmit_lock_owner = -1;
146 spin_unlock(&dev->xmit_lock);
148 spin_lock(&dev->queue_lock);
151 if (ret == NETDEV_TX_LOCKED && nolock) {
152 spin_lock(&dev->queue_lock);
157 /* NETDEV_TX_BUSY - we need to requeue */
158 /* Release the driver */
160 dev->xmit_lock_owner = -1;
161 spin_unlock(&dev->xmit_lock);
163 spin_lock(&dev->queue_lock);
167 /* Device kicked us out :(
168 This is possible in three cases:
171 1. fastroute is enabled
172 2. device cannot determine busy state
173 before start of transmission (f.e. dialout)
174 3. device is buggy (ppp)
178 q->ops->requeue(skb, q);
182 BUG_ON((int) q->q.qlen < 0);
186 static void dev_watchdog(unsigned long arg)
188 struct net_device *dev = (struct net_device *)arg;
190 spin_lock(&dev->xmit_lock);
191 if (dev->qdisc != &noop_qdisc) {
192 if (netif_device_present(dev) &&
193 netif_running(dev) &&
194 netif_carrier_ok(dev)) {
195 if (netif_queue_stopped(dev) &&
196 time_after(jiffies, dev->trans_start + dev->watchdog_timeo)) {
198 printk(KERN_INFO "NETDEV WATCHDOG: %s: transmit timed out\n",
200 dev->tx_timeout(dev);
202 if (!mod_timer(&dev->watchdog_timer, jiffies + dev->watchdog_timeo))
206 spin_unlock(&dev->xmit_lock);
211 static void dev_watchdog_init(struct net_device *dev)
213 init_timer(&dev->watchdog_timer);
214 dev->watchdog_timer.data = (unsigned long)dev;
215 dev->watchdog_timer.function = dev_watchdog;
218 void __netdev_watchdog_up(struct net_device *dev)
220 if (dev->tx_timeout) {
221 if (dev->watchdog_timeo <= 0)
222 dev->watchdog_timeo = 5*HZ;
223 if (!mod_timer(&dev->watchdog_timer, jiffies + dev->watchdog_timeo))
228 static void dev_watchdog_up(struct net_device *dev)
230 spin_lock_bh(&dev->xmit_lock);
231 __netdev_watchdog_up(dev);
232 spin_unlock_bh(&dev->xmit_lock);
235 static void dev_watchdog_down(struct net_device *dev)
237 spin_lock_bh(&dev->xmit_lock);
238 if (del_timer(&dev->watchdog_timer))
240 spin_unlock_bh(&dev->xmit_lock);
243 void netif_carrier_on(struct net_device *dev)
245 if (test_and_clear_bit(__LINK_STATE_NOCARRIER, &dev->state))
246 linkwatch_fire_event(dev);
247 if (netif_running(dev))
248 __netdev_watchdog_up(dev);
251 void netif_carrier_off(struct net_device *dev)
253 if (!test_and_set_bit(__LINK_STATE_NOCARRIER, &dev->state))
254 linkwatch_fire_event(dev);
257 /* "NOOP" scheduler: the best scheduler, recommended for all interfaces
258 under all circumstances. It is difficult to invent anything faster or
262 static int noop_enqueue(struct sk_buff *skb, struct Qdisc * qdisc)
268 static struct sk_buff *noop_dequeue(struct Qdisc * qdisc)
273 static int noop_requeue(struct sk_buff *skb, struct Qdisc* qdisc)
276 printk(KERN_DEBUG "%s deferred output. It is buggy.\n",
282 struct Qdisc_ops noop_qdisc_ops = {
285 .enqueue = noop_enqueue,
286 .dequeue = noop_dequeue,
287 .requeue = noop_requeue,
288 .owner = THIS_MODULE,
291 struct Qdisc noop_qdisc = {
292 .enqueue = noop_enqueue,
293 .dequeue = noop_dequeue,
294 .flags = TCQ_F_BUILTIN,
295 .ops = &noop_qdisc_ops,
296 .list = LIST_HEAD_INIT(noop_qdisc.list),
299 static struct Qdisc_ops noqueue_qdisc_ops = {
302 .enqueue = noop_enqueue,
303 .dequeue = noop_dequeue,
304 .requeue = noop_requeue,
305 .owner = THIS_MODULE,
308 static struct Qdisc noqueue_qdisc = {
310 .dequeue = noop_dequeue,
311 .flags = TCQ_F_BUILTIN,
312 .ops = &noqueue_qdisc_ops,
313 .list = LIST_HEAD_INIT(noqueue_qdisc.list),
317 static const u8 prio2band[TC_PRIO_MAX+1] =
318 { 1, 2, 2, 2, 1, 2, 0, 0 , 1, 1, 1, 1, 1, 1, 1, 1 };
320 /* 3-band FIFO queue: old style, but should be a bit faster than
321 generic prio+fifo combination.
324 #define PFIFO_FAST_BANDS 3
326 static inline struct sk_buff_head *prio2list(struct sk_buff *skb,
329 struct sk_buff_head *list = qdisc_priv(qdisc);
330 return list + prio2band[skb->priority & TC_PRIO_MAX];
333 static int pfifo_fast_enqueue(struct sk_buff *skb, struct Qdisc* qdisc)
335 struct sk_buff_head *list = prio2list(skb, qdisc);
337 if (skb_queue_len(list) < qdisc->dev->tx_queue_len) {
339 return __qdisc_enqueue_tail(skb, qdisc, list);
342 return qdisc_drop(skb, qdisc);
345 static struct sk_buff *pfifo_fast_dequeue(struct Qdisc* qdisc)
348 struct sk_buff_head *list = qdisc_priv(qdisc);
350 for (prio = 0; prio < PFIFO_FAST_BANDS; prio++) {
351 if (!skb_queue_empty(list + prio)) {
353 return __qdisc_dequeue_head(qdisc, list + prio);
360 static int pfifo_fast_requeue(struct sk_buff *skb, struct Qdisc* qdisc)
363 return __qdisc_requeue(skb, qdisc, prio2list(skb, qdisc));
366 static void pfifo_fast_reset(struct Qdisc* qdisc)
369 struct sk_buff_head *list = qdisc_priv(qdisc);
371 for (prio = 0; prio < PFIFO_FAST_BANDS; prio++)
372 __qdisc_reset_queue(qdisc, list + prio);
374 qdisc->qstats.backlog = 0;
378 static int pfifo_fast_dump(struct Qdisc *qdisc, struct sk_buff *skb)
380 struct tc_prio_qopt opt = { .bands = PFIFO_FAST_BANDS };
382 memcpy(&opt.priomap, prio2band, TC_PRIO_MAX+1);
383 RTA_PUT(skb, TCA_OPTIONS, sizeof(opt), &opt);
390 static int pfifo_fast_init(struct Qdisc *qdisc, struct rtattr *opt)
393 struct sk_buff_head *list = qdisc_priv(qdisc);
395 for (prio = 0; prio < PFIFO_FAST_BANDS; prio++)
396 skb_queue_head_init(list + prio);
401 static struct Qdisc_ops pfifo_fast_ops = {
403 .priv_size = PFIFO_FAST_BANDS * sizeof(struct sk_buff_head),
404 .enqueue = pfifo_fast_enqueue,
405 .dequeue = pfifo_fast_dequeue,
406 .requeue = pfifo_fast_requeue,
407 .init = pfifo_fast_init,
408 .reset = pfifo_fast_reset,
409 .dump = pfifo_fast_dump,
410 .owner = THIS_MODULE,
413 struct Qdisc *qdisc_alloc(struct net_device *dev, struct Qdisc_ops *ops)
420 /* ensure that the Qdisc and the private data are 32-byte aligned */
421 size = QDISC_ALIGN(sizeof(*sch));
422 size += ops->priv_size + (QDISC_ALIGNTO - 1);
424 p = kmalloc(size, GFP_KERNEL);
428 sch = (struct Qdisc *) QDISC_ALIGN((unsigned long) p);
429 sch->padded = (char *) sch - (char *) p;
431 INIT_LIST_HEAD(&sch->list);
432 skb_queue_head_init(&sch->q);
434 sch->enqueue = ops->enqueue;
435 sch->dequeue = ops->dequeue;
438 sch->stats_lock = &dev->queue_lock;
439 atomic_set(&sch->refcnt, 1);
443 return ERR_PTR(-err);
446 struct Qdisc * qdisc_create_dflt(struct net_device *dev, struct Qdisc_ops *ops)
450 sch = qdisc_alloc(dev, ops);
454 if (!ops->init || ops->init(sch, NULL) == 0)
462 /* Under dev->queue_lock and BH! */
464 void qdisc_reset(struct Qdisc *qdisc)
466 struct Qdisc_ops *ops = qdisc->ops;
472 /* this is the rcu callback function to clean up a qdisc when there
473 * are no further references to it */
475 static void __qdisc_destroy(struct rcu_head *head)
477 struct Qdisc *qdisc = container_of(head, struct Qdisc, q_rcu);
478 struct Qdisc_ops *ops = qdisc->ops;
480 #ifdef CONFIG_NET_ESTIMATOR
481 gen_kill_estimator(&qdisc->bstats, &qdisc->rate_est);
483 write_lock(&qdisc_tree_lock);
488 write_unlock(&qdisc_tree_lock);
489 module_put(ops->owner);
492 kfree((char *) qdisc - qdisc->padded);
495 /* Under dev->queue_lock and BH! */
497 void qdisc_destroy(struct Qdisc *qdisc)
499 struct list_head cql = LIST_HEAD_INIT(cql);
500 struct Qdisc *cq, *q, *n;
502 if (qdisc->flags & TCQ_F_BUILTIN ||
503 !atomic_dec_and_test(&qdisc->refcnt))
506 if (!list_empty(&qdisc->list)) {
507 if (qdisc->ops->cl_ops == NULL)
508 list_del(&qdisc->list);
510 list_move(&qdisc->list, &cql);
513 /* unlink inner qdiscs from dev->qdisc_list immediately */
514 list_for_each_entry(cq, &cql, list)
515 list_for_each_entry_safe(q, n, &qdisc->dev->qdisc_list, list)
516 if (TC_H_MAJ(q->parent) == TC_H_MAJ(cq->handle)) {
517 if (q->ops->cl_ops == NULL)
518 list_del_init(&q->list);
520 list_move_tail(&q->list, &cql);
522 list_for_each_entry_safe(cq, n, &cql, list)
523 list_del_init(&cq->list);
525 call_rcu(&qdisc->q_rcu, __qdisc_destroy);
528 void dev_activate(struct net_device *dev)
530 /* No queueing discipline is attached to device;
531 create default one i.e. pfifo_fast for devices,
532 which need queueing and noqueue_qdisc for
536 if (dev->qdisc_sleeping == &noop_qdisc) {
538 if (dev->tx_queue_len) {
539 qdisc = qdisc_create_dflt(dev, &pfifo_fast_ops);
541 printk(KERN_INFO "%s: activation failed\n", dev->name);
544 write_lock_bh(&qdisc_tree_lock);
545 list_add_tail(&qdisc->list, &dev->qdisc_list);
546 write_unlock_bh(&qdisc_tree_lock);
548 qdisc = &noqueue_qdisc;
550 write_lock_bh(&qdisc_tree_lock);
551 dev->qdisc_sleeping = qdisc;
552 write_unlock_bh(&qdisc_tree_lock);
555 if (!netif_carrier_ok(dev))
556 /* Delay activation until next carrier-on event */
559 spin_lock_bh(&dev->queue_lock);
560 rcu_assign_pointer(dev->qdisc, dev->qdisc_sleeping);
561 if (dev->qdisc != &noqueue_qdisc) {
562 dev->trans_start = jiffies;
563 dev_watchdog_up(dev);
565 spin_unlock_bh(&dev->queue_lock);
568 void dev_deactivate(struct net_device *dev)
572 spin_lock_bh(&dev->queue_lock);
574 dev->qdisc = &noop_qdisc;
578 spin_unlock_bh(&dev->queue_lock);
580 dev_watchdog_down(dev);
582 while (test_bit(__LINK_STATE_SCHED, &dev->state))
585 spin_unlock_wait(&dev->xmit_lock);
588 void dev_init_scheduler(struct net_device *dev)
590 qdisc_lock_tree(dev);
591 dev->qdisc = &noop_qdisc;
592 dev->qdisc_sleeping = &noop_qdisc;
593 INIT_LIST_HEAD(&dev->qdisc_list);
594 qdisc_unlock_tree(dev);
596 dev_watchdog_init(dev);
599 void dev_shutdown(struct net_device *dev)
603 qdisc_lock_tree(dev);
604 qdisc = dev->qdisc_sleeping;
605 dev->qdisc = &noop_qdisc;
606 dev->qdisc_sleeping = &noop_qdisc;
607 qdisc_destroy(qdisc);
608 #if defined(CONFIG_NET_SCH_INGRESS) || defined(CONFIG_NET_SCH_INGRESS_MODULE)
609 if ((qdisc = dev->qdisc_ingress) != NULL) {
610 dev->qdisc_ingress = NULL;
611 qdisc_destroy(qdisc);
614 BUG_TRAP(!timer_pending(&dev->watchdog_timer));
615 qdisc_unlock_tree(dev);
618 EXPORT_SYMBOL(__netdev_watchdog_up);
619 EXPORT_SYMBOL(netif_carrier_on);
620 EXPORT_SYMBOL(netif_carrier_off);
621 EXPORT_SYMBOL(noop_qdisc);
622 EXPORT_SYMBOL(noop_qdisc_ops);
623 EXPORT_SYMBOL(qdisc_create_dflt);
624 EXPORT_SYMBOL(qdisc_alloc);
625 EXPORT_SYMBOL(qdisc_destroy);
626 EXPORT_SYMBOL(qdisc_reset);
627 EXPORT_SYMBOL(qdisc_restart);
628 EXPORT_SYMBOL(qdisc_lock_tree);
629 EXPORT_SYMBOL(qdisc_unlock_tree);