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
, jiffies
+ dev
->watchdog_timeo
))
232 static void dev_watchdog_up(struct net_device
*dev
)
234 __netdev_watchdog_up(dev
);
237 static void dev_watchdog_down(struct net_device
*dev
)
239 netif_tx_lock_bh(dev
);
240 if (del_timer(&dev
->watchdog_timer
))
242 netif_tx_unlock_bh(dev
);
245 void netif_carrier_on(struct net_device
*dev
)
247 if (test_and_clear_bit(__LINK_STATE_NOCARRIER
, &dev
->state
))
248 linkwatch_fire_event(dev
);
249 if (netif_running(dev
))
250 __netdev_watchdog_up(dev
);
253 void netif_carrier_off(struct net_device
*dev
)
255 if (!test_and_set_bit(__LINK_STATE_NOCARRIER
, &dev
->state
))
256 linkwatch_fire_event(dev
);
259 /* "NOOP" scheduler: the best scheduler, recommended for all interfaces
260 under all circumstances. It is difficult to invent anything faster or
264 static int noop_enqueue(struct sk_buff
*skb
, struct Qdisc
* qdisc
)
270 static struct sk_buff
*noop_dequeue(struct Qdisc
* qdisc
)
275 static int noop_requeue(struct sk_buff
*skb
, struct Qdisc
* qdisc
)
278 printk(KERN_DEBUG
"%s deferred output. It is buggy.\n",
284 struct Qdisc_ops noop_qdisc_ops
= {
287 .enqueue
= noop_enqueue
,
288 .dequeue
= noop_dequeue
,
289 .requeue
= noop_requeue
,
290 .owner
= THIS_MODULE
,
293 struct Qdisc noop_qdisc
= {
294 .enqueue
= noop_enqueue
,
295 .dequeue
= noop_dequeue
,
296 .flags
= TCQ_F_BUILTIN
,
297 .ops
= &noop_qdisc_ops
,
298 .list
= LIST_HEAD_INIT(noop_qdisc
.list
),
301 static struct Qdisc_ops noqueue_qdisc_ops
= {
304 .enqueue
= noop_enqueue
,
305 .dequeue
= noop_dequeue
,
306 .requeue
= noop_requeue
,
307 .owner
= THIS_MODULE
,
310 static struct Qdisc noqueue_qdisc
= {
312 .dequeue
= noop_dequeue
,
313 .flags
= TCQ_F_BUILTIN
,
314 .ops
= &noqueue_qdisc_ops
,
315 .list
= LIST_HEAD_INIT(noqueue_qdisc
.list
),
319 static const u8 prio2band
[TC_PRIO_MAX
+1] =
320 { 1, 2, 2, 2, 1, 2, 0, 0 , 1, 1, 1, 1, 1, 1, 1, 1 };
322 /* 3-band FIFO queue: old style, but should be a bit faster than
323 generic prio+fifo combination.
326 #define PFIFO_FAST_BANDS 3
328 static inline struct sk_buff_head
*prio2list(struct sk_buff
*skb
,
331 struct sk_buff_head
*list
= qdisc_priv(qdisc
);
332 return list
+ prio2band
[skb
->priority
& TC_PRIO_MAX
];
335 static int pfifo_fast_enqueue(struct sk_buff
*skb
, struct Qdisc
* qdisc
)
337 struct sk_buff_head
*list
= prio2list(skb
, qdisc
);
339 if (skb_queue_len(list
) < qdisc
->dev
->tx_queue_len
) {
341 return __qdisc_enqueue_tail(skb
, qdisc
, list
);
344 return qdisc_drop(skb
, qdisc
);
347 static struct sk_buff
*pfifo_fast_dequeue(struct Qdisc
* qdisc
)
350 struct sk_buff_head
*list
= qdisc_priv(qdisc
);
352 for (prio
= 0; prio
< PFIFO_FAST_BANDS
; prio
++) {
353 if (!skb_queue_empty(list
+ prio
)) {
355 return __qdisc_dequeue_head(qdisc
, list
+ prio
);
362 static int pfifo_fast_requeue(struct sk_buff
*skb
, struct Qdisc
* qdisc
)
365 return __qdisc_requeue(skb
, qdisc
, prio2list(skb
, qdisc
));
368 static void pfifo_fast_reset(struct Qdisc
* qdisc
)
371 struct sk_buff_head
*list
= qdisc_priv(qdisc
);
373 for (prio
= 0; prio
< PFIFO_FAST_BANDS
; prio
++)
374 __qdisc_reset_queue(qdisc
, list
+ prio
);
376 qdisc
->qstats
.backlog
= 0;
380 static int pfifo_fast_dump(struct Qdisc
*qdisc
, struct sk_buff
*skb
)
382 struct tc_prio_qopt opt
= { .bands
= PFIFO_FAST_BANDS
};
384 memcpy(&opt
.priomap
, prio2band
, TC_PRIO_MAX
+1);
385 RTA_PUT(skb
, TCA_OPTIONS
, sizeof(opt
), &opt
);
392 static int pfifo_fast_init(struct Qdisc
*qdisc
, struct rtattr
*opt
)
395 struct sk_buff_head
*list
= qdisc_priv(qdisc
);
397 for (prio
= 0; prio
< PFIFO_FAST_BANDS
; prio
++)
398 skb_queue_head_init(list
+ prio
);
403 static struct Qdisc_ops pfifo_fast_ops
= {
405 .priv_size
= PFIFO_FAST_BANDS
* sizeof(struct sk_buff_head
),
406 .enqueue
= pfifo_fast_enqueue
,
407 .dequeue
= pfifo_fast_dequeue
,
408 .requeue
= pfifo_fast_requeue
,
409 .init
= pfifo_fast_init
,
410 .reset
= pfifo_fast_reset
,
411 .dump
= pfifo_fast_dump
,
412 .owner
= THIS_MODULE
,
415 struct Qdisc
*qdisc_alloc(struct net_device
*dev
, struct Qdisc_ops
*ops
)
422 /* ensure that the Qdisc and the private data are 32-byte aligned */
423 size
= QDISC_ALIGN(sizeof(*sch
));
424 size
+= ops
->priv_size
+ (QDISC_ALIGNTO
- 1);
426 p
= kzalloc(size
, GFP_KERNEL
);
429 sch
= (struct Qdisc
*) QDISC_ALIGN((unsigned long) p
);
430 sch
->padded
= (char *) sch
- (char *) p
;
432 INIT_LIST_HEAD(&sch
->list
);
433 skb_queue_head_init(&sch
->q
);
435 sch
->enqueue
= ops
->enqueue
;
436 sch
->dequeue
= ops
->dequeue
;
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
,
447 unsigned int parentid
)
451 sch
= qdisc_alloc(dev
, ops
);
454 sch
->stats_lock
= &dev
->queue_lock
;
455 sch
->parent
= parentid
;
457 if (!ops
->init
|| ops
->init(sch
, NULL
) == 0)
465 /* Under dev->queue_lock and BH! */
467 void qdisc_reset(struct Qdisc
*qdisc
)
469 struct Qdisc_ops
*ops
= qdisc
->ops
;
475 /* this is the rcu callback function to clean up a qdisc when there
476 * are no further references to it */
478 static void __qdisc_destroy(struct rcu_head
*head
)
480 struct Qdisc
*qdisc
= container_of(head
, struct Qdisc
, q_rcu
);
481 kfree((char *) qdisc
- qdisc
->padded
);
484 /* Under dev->queue_lock and BH! */
486 void qdisc_destroy(struct Qdisc
*qdisc
)
488 struct Qdisc_ops
*ops
= qdisc
->ops
;
490 if (qdisc
->flags
& TCQ_F_BUILTIN
||
491 !atomic_dec_and_test(&qdisc
->refcnt
))
494 list_del(&qdisc
->list
);
495 #ifdef CONFIG_NET_ESTIMATOR
496 gen_kill_estimator(&qdisc
->bstats
, &qdisc
->rate_est
);
503 module_put(ops
->owner
);
505 call_rcu(&qdisc
->q_rcu
, __qdisc_destroy
);
508 void dev_activate(struct net_device
*dev
)
510 /* No queueing discipline is attached to device;
511 create default one i.e. pfifo_fast for devices,
512 which need queueing and noqueue_qdisc for
516 if (dev
->qdisc_sleeping
== &noop_qdisc
) {
518 if (dev
->tx_queue_len
) {
519 qdisc
= qdisc_create_dflt(dev
, &pfifo_fast_ops
,
522 printk(KERN_INFO
"%s: activation failed\n", dev
->name
);
525 list_add_tail(&qdisc
->list
, &dev
->qdisc_list
);
527 qdisc
= &noqueue_qdisc
;
529 dev
->qdisc_sleeping
= qdisc
;
532 if (!netif_carrier_ok(dev
))
533 /* Delay activation until next carrier-on event */
536 spin_lock_bh(&dev
->queue_lock
);
537 rcu_assign_pointer(dev
->qdisc
, dev
->qdisc_sleeping
);
538 if (dev
->qdisc
!= &noqueue_qdisc
) {
539 dev
->trans_start
= jiffies
;
540 dev_watchdog_up(dev
);
542 spin_unlock_bh(&dev
->queue_lock
);
545 void dev_deactivate(struct net_device
*dev
)
550 spin_lock_bh(&dev
->queue_lock
);
552 dev
->qdisc
= &noop_qdisc
;
558 spin_unlock_bh(&dev
->queue_lock
);
562 dev_watchdog_down(dev
);
564 /* Wait for outstanding dev_queue_xmit calls. */
567 /* Wait for outstanding qdisc_run calls. */
568 while (test_bit(__LINK_STATE_QDISC_RUNNING
, &dev
->state
))
572 void dev_init_scheduler(struct net_device
*dev
)
574 qdisc_lock_tree(dev
);
575 dev
->qdisc
= &noop_qdisc
;
576 dev
->qdisc_sleeping
= &noop_qdisc
;
577 INIT_LIST_HEAD(&dev
->qdisc_list
);
578 qdisc_unlock_tree(dev
);
580 dev_watchdog_init(dev
);
583 void dev_shutdown(struct net_device
*dev
)
587 qdisc_lock_tree(dev
);
588 qdisc
= dev
->qdisc_sleeping
;
589 dev
->qdisc
= &noop_qdisc
;
590 dev
->qdisc_sleeping
= &noop_qdisc
;
591 qdisc_destroy(qdisc
);
592 #if defined(CONFIG_NET_SCH_INGRESS) || defined(CONFIG_NET_SCH_INGRESS_MODULE)
593 if ((qdisc
= dev
->qdisc_ingress
) != NULL
) {
594 dev
->qdisc_ingress
= NULL
;
595 qdisc_destroy(qdisc
);
598 BUG_TRAP(!timer_pending(&dev
->watchdog_timer
));
599 qdisc_unlock_tree(dev
);
602 EXPORT_SYMBOL(netif_carrier_on
);
603 EXPORT_SYMBOL(netif_carrier_off
);
604 EXPORT_SYMBOL(noop_qdisc
);
605 EXPORT_SYMBOL(qdisc_create_dflt
);
606 EXPORT_SYMBOL(qdisc_destroy
);
607 EXPORT_SYMBOL(qdisc_reset
);
608 EXPORT_SYMBOL(qdisc_lock_tree
);
609 EXPORT_SYMBOL(qdisc_unlock_tree
);