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 <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>
29 /* Main transmission queue. */
31 /* Modifications to data participating in scheduling must be protected with
32 * qdisc_lock(qdisc) spinlock.
34 * The idea is the following:
35 * - enqueue, dequeue are serialized via qdisc root lock
36 * - ingress filtering is also serialized via qdisc root lock
37 * - updates to tree and tree walking are only done under the rtnl mutex.
40 static inline int qdisc_qlen(struct Qdisc
*q
)
45 static inline int dev_requeue_skb(struct sk_buff
*skb
, struct Qdisc
*q
)
54 static inline struct sk_buff
*dequeue_skb(struct Qdisc
*q
)
56 struct sk_buff
*skb
= q
->gso_skb
;
59 struct net_device
*dev
= qdisc_dev(q
);
60 struct netdev_queue
*txq
;
62 /* check the reason of requeuing without tx lock first */
63 txq
= netdev_get_tx_queue(dev
, skb_get_queue_mapping(skb
));
64 if (!netif_tx_queue_stopped(txq
) && !netif_tx_queue_frozen(txq
))
75 static inline int handle_dev_cpu_collision(struct sk_buff
*skb
,
76 struct netdev_queue
*dev_queue
,
81 if (unlikely(dev_queue
->xmit_lock_owner
== smp_processor_id())) {
83 * Same CPU holding the lock. It may be a transient
84 * configuration error, when hard_start_xmit() recurses. We
85 * detect it by checking xmit owner and drop the packet when
86 * deadloop is detected. Return OK to try the next skb.
90 printk(KERN_WARNING
"Dead loop on netdevice %s, "
91 "fix it urgently!\n", dev_queue
->dev
->name
);
95 * Another cpu is holding lock, requeue & delay xmits for
98 __get_cpu_var(netdev_rx_stat
).cpu_collision
++;
99 ret
= dev_requeue_skb(skb
, q
);
106 * NOTE: Called under qdisc_lock(q) with locally disabled BH.
108 * __QDISC_STATE_RUNNING guarantees only one CPU can process
109 * this qdisc at a time. qdisc_lock(q) serializes queue accesses for
112 * netif_tx_lock serializes accesses to device driver.
114 * qdisc_lock(q) and netif_tx_lock are mutually exclusive,
115 * if one is grabbed, another must be free.
117 * Note, that this procedure can be called by a watchdog timer
119 * Returns to the caller:
120 * 0 - queue is empty or throttled.
121 * >0 - queue is not empty.
124 static inline int qdisc_restart(struct Qdisc
*q
)
126 struct netdev_queue
*txq
;
127 int ret
= NETDEV_TX_BUSY
;
128 struct net_device
*dev
;
129 spinlock_t
*root_lock
;
133 if (unlikely((skb
= dequeue_skb(q
)) == NULL
))
136 root_lock
= qdisc_lock(q
);
138 /* And release qdisc */
139 spin_unlock(root_lock
);
142 txq
= netdev_get_tx_queue(dev
, skb_get_queue_mapping(skb
));
144 HARD_TX_LOCK(dev
, txq
, smp_processor_id());
145 if (!netif_tx_queue_stopped(txq
) &&
146 !netif_tx_queue_frozen(txq
))
147 ret
= dev_hard_start_xmit(skb
, dev
, txq
);
148 HARD_TX_UNLOCK(dev
, txq
);
150 spin_lock(root_lock
);
154 /* Driver sent out skb successfully */
158 case NETDEV_TX_LOCKED
:
159 /* Driver try lock failed */
160 ret
= handle_dev_cpu_collision(skb
, txq
, q
);
164 /* Driver returned NETDEV_TX_BUSY - requeue skb */
165 if (unlikely (ret
!= NETDEV_TX_BUSY
&& net_ratelimit()))
166 printk(KERN_WARNING
"BUG %s code %d qlen %d\n",
167 dev
->name
, ret
, q
->q
.qlen
);
169 ret
= dev_requeue_skb(skb
, q
);
173 if (ret
&& (netif_tx_queue_stopped(txq
) ||
174 netif_tx_queue_frozen(txq
)))
180 void __qdisc_run(struct Qdisc
*q
)
182 unsigned long start_time
= jiffies
;
184 while (qdisc_restart(q
)) {
186 * Postpone processing if
187 * 1. another process needs the CPU;
188 * 2. we've been doing it for too long.
190 if (need_resched() || jiffies
!= start_time
) {
196 clear_bit(__QDISC_STATE_RUNNING
, &q
->state
);
199 static void dev_watchdog(unsigned long arg
)
201 struct net_device
*dev
= (struct net_device
*)arg
;
204 if (!qdisc_tx_is_noop(dev
)) {
205 if (netif_device_present(dev
) &&
206 netif_running(dev
) &&
207 netif_carrier_ok(dev
)) {
208 int some_queue_stopped
= 0;
211 for (i
= 0; i
< dev
->num_tx_queues
; i
++) {
212 struct netdev_queue
*txq
;
214 txq
= netdev_get_tx_queue(dev
, i
);
215 if (netif_tx_queue_stopped(txq
)) {
216 some_queue_stopped
= 1;
221 if (some_queue_stopped
&&
222 time_after(jiffies
, (dev
->trans_start
+
223 dev
->watchdog_timeo
))) {
225 WARN_ONCE(1, KERN_INFO
"NETDEV WATCHDOG: %s (%s): transmit timed out\n",
226 dev
->name
, netdev_drivername(dev
, drivername
, 64));
227 dev
->tx_timeout(dev
);
229 if (!mod_timer(&dev
->watchdog_timer
,
230 round_jiffies(jiffies
+
231 dev
->watchdog_timeo
)))
235 netif_tx_unlock(dev
);
240 void __netdev_watchdog_up(struct net_device
*dev
)
242 if (dev
->tx_timeout
) {
243 if (dev
->watchdog_timeo
<= 0)
244 dev
->watchdog_timeo
= 5*HZ
;
245 if (!mod_timer(&dev
->watchdog_timer
,
246 round_jiffies(jiffies
+ dev
->watchdog_timeo
)))
251 static void dev_watchdog_up(struct net_device
*dev
)
253 __netdev_watchdog_up(dev
);
256 static void dev_watchdog_down(struct net_device
*dev
)
258 netif_tx_lock_bh(dev
);
259 if (del_timer(&dev
->watchdog_timer
))
261 netif_tx_unlock_bh(dev
);
265 * netif_carrier_on - set carrier
266 * @dev: network device
268 * Device has detected that carrier.
270 void netif_carrier_on(struct net_device
*dev
)
272 if (test_and_clear_bit(__LINK_STATE_NOCARRIER
, &dev
->state
)) {
273 if (dev
->reg_state
== NETREG_UNINITIALIZED
)
275 linkwatch_fire_event(dev
);
276 if (netif_running(dev
))
277 __netdev_watchdog_up(dev
);
280 EXPORT_SYMBOL(netif_carrier_on
);
283 * netif_carrier_off - clear carrier
284 * @dev: network device
286 * Device has detected loss of carrier.
288 void netif_carrier_off(struct net_device
*dev
)
290 if (!test_and_set_bit(__LINK_STATE_NOCARRIER
, &dev
->state
)) {
291 if (dev
->reg_state
== NETREG_UNINITIALIZED
)
293 linkwatch_fire_event(dev
);
296 EXPORT_SYMBOL(netif_carrier_off
);
298 /* "NOOP" scheduler: the best scheduler, recommended for all interfaces
299 under all circumstances. It is difficult to invent anything faster or
303 static int noop_enqueue(struct sk_buff
*skb
, struct Qdisc
* qdisc
)
309 static struct sk_buff
*noop_dequeue(struct Qdisc
* qdisc
)
314 static int noop_requeue(struct sk_buff
*skb
, struct Qdisc
* qdisc
)
317 printk(KERN_DEBUG
"%s deferred output. It is buggy.\n",
323 struct Qdisc_ops noop_qdisc_ops __read_mostly
= {
326 .enqueue
= noop_enqueue
,
327 .dequeue
= noop_dequeue
,
328 .requeue
= noop_requeue
,
329 .owner
= THIS_MODULE
,
332 static struct netdev_queue noop_netdev_queue
= {
333 .qdisc
= &noop_qdisc
,
334 .qdisc_sleeping
= &noop_qdisc
,
337 struct Qdisc noop_qdisc
= {
338 .enqueue
= noop_enqueue
,
339 .dequeue
= noop_dequeue
,
340 .flags
= TCQ_F_BUILTIN
,
341 .ops
= &noop_qdisc_ops
,
342 .list
= LIST_HEAD_INIT(noop_qdisc
.list
),
343 .requeue
.lock
= __SPIN_LOCK_UNLOCKED(noop_qdisc
.q
.lock
),
344 .q
.lock
= __SPIN_LOCK_UNLOCKED(noop_qdisc
.q
.lock
),
345 .dev_queue
= &noop_netdev_queue
,
347 EXPORT_SYMBOL(noop_qdisc
);
349 static struct Qdisc_ops noqueue_qdisc_ops __read_mostly
= {
352 .enqueue
= noop_enqueue
,
353 .dequeue
= noop_dequeue
,
354 .requeue
= noop_requeue
,
355 .owner
= THIS_MODULE
,
358 static struct Qdisc noqueue_qdisc
;
359 static struct netdev_queue noqueue_netdev_queue
= {
360 .qdisc
= &noqueue_qdisc
,
361 .qdisc_sleeping
= &noqueue_qdisc
,
364 static struct Qdisc noqueue_qdisc
= {
366 .dequeue
= noop_dequeue
,
367 .flags
= TCQ_F_BUILTIN
,
368 .ops
= &noqueue_qdisc_ops
,
369 .list
= LIST_HEAD_INIT(noqueue_qdisc
.list
),
370 .requeue
.lock
= __SPIN_LOCK_UNLOCKED(noqueue_qdisc
.q
.lock
),
371 .q
.lock
= __SPIN_LOCK_UNLOCKED(noqueue_qdisc
.q
.lock
),
372 .dev_queue
= &noqueue_netdev_queue
,
376 static const u8 prio2band
[TC_PRIO_MAX
+1] =
377 { 1, 2, 2, 2, 1, 2, 0, 0 , 1, 1, 1, 1, 1, 1, 1, 1 };
379 /* 3-band FIFO queue: old style, but should be a bit faster than
380 generic prio+fifo combination.
383 #define PFIFO_FAST_BANDS 3
385 static inline struct sk_buff_head
*prio2list(struct sk_buff
*skb
,
388 struct sk_buff_head
*list
= qdisc_priv(qdisc
);
389 return list
+ prio2band
[skb
->priority
& TC_PRIO_MAX
];
392 static int pfifo_fast_enqueue(struct sk_buff
*skb
, struct Qdisc
* qdisc
)
394 struct sk_buff_head
*list
= prio2list(skb
, qdisc
);
396 if (skb_queue_len(list
) < qdisc_dev(qdisc
)->tx_queue_len
) {
398 return __qdisc_enqueue_tail(skb
, qdisc
, list
);
401 return qdisc_drop(skb
, qdisc
);
404 static struct sk_buff
*pfifo_fast_dequeue(struct Qdisc
* qdisc
)
407 struct sk_buff_head
*list
= qdisc_priv(qdisc
);
409 for (prio
= 0; prio
< PFIFO_FAST_BANDS
; prio
++) {
410 if (!skb_queue_empty(list
+ prio
)) {
412 return __qdisc_dequeue_head(qdisc
, list
+ prio
);
419 static int pfifo_fast_requeue(struct sk_buff
*skb
, struct Qdisc
* qdisc
)
422 return __qdisc_requeue(skb
, qdisc
, prio2list(skb
, qdisc
));
425 static void pfifo_fast_reset(struct Qdisc
* qdisc
)
428 struct sk_buff_head
*list
= qdisc_priv(qdisc
);
430 for (prio
= 0; prio
< PFIFO_FAST_BANDS
; prio
++)
431 __qdisc_reset_queue(qdisc
, list
+ prio
);
433 qdisc
->qstats
.backlog
= 0;
437 static int pfifo_fast_dump(struct Qdisc
*qdisc
, struct sk_buff
*skb
)
439 struct tc_prio_qopt opt
= { .bands
= PFIFO_FAST_BANDS
};
441 memcpy(&opt
.priomap
, prio2band
, TC_PRIO_MAX
+1);
442 NLA_PUT(skb
, TCA_OPTIONS
, sizeof(opt
), &opt
);
449 static int pfifo_fast_init(struct Qdisc
*qdisc
, struct nlattr
*opt
)
452 struct sk_buff_head
*list
= qdisc_priv(qdisc
);
454 for (prio
= 0; prio
< PFIFO_FAST_BANDS
; prio
++)
455 skb_queue_head_init(list
+ prio
);
460 static struct Qdisc_ops pfifo_fast_ops __read_mostly
= {
462 .priv_size
= PFIFO_FAST_BANDS
* sizeof(struct sk_buff_head
),
463 .enqueue
= pfifo_fast_enqueue
,
464 .dequeue
= pfifo_fast_dequeue
,
465 .requeue
= pfifo_fast_requeue
,
466 .init
= pfifo_fast_init
,
467 .reset
= pfifo_fast_reset
,
468 .dump
= pfifo_fast_dump
,
469 .owner
= THIS_MODULE
,
472 struct Qdisc
*qdisc_alloc(struct netdev_queue
*dev_queue
,
473 struct Qdisc_ops
*ops
)
480 /* ensure that the Qdisc and the private data are 32-byte aligned */
481 size
= QDISC_ALIGN(sizeof(*sch
));
482 size
+= ops
->priv_size
+ (QDISC_ALIGNTO
- 1);
484 p
= kzalloc(size
, GFP_KERNEL
);
487 sch
= (struct Qdisc
*) QDISC_ALIGN((unsigned long) p
);
488 sch
->padded
= (char *) sch
- (char *) p
;
490 INIT_LIST_HEAD(&sch
->list
);
491 skb_queue_head_init(&sch
->requeue
);
492 skb_queue_head_init(&sch
->q
);
494 sch
->enqueue
= ops
->enqueue
;
495 sch
->dequeue
= ops
->dequeue
;
496 sch
->dev_queue
= dev_queue
;
497 dev_hold(qdisc_dev(sch
));
498 atomic_set(&sch
->refcnt
, 1);
505 struct Qdisc
* qdisc_create_dflt(struct net_device
*dev
,
506 struct netdev_queue
*dev_queue
,
507 struct Qdisc_ops
*ops
,
508 unsigned int parentid
)
512 sch
= qdisc_alloc(dev_queue
, ops
);
515 sch
->parent
= parentid
;
517 if (!ops
->init
|| ops
->init(sch
, NULL
) == 0)
524 EXPORT_SYMBOL(qdisc_create_dflt
);
526 /* Under qdisc_lock(qdisc) and BH! */
528 void qdisc_reset(struct Qdisc
*qdisc
)
530 const struct Qdisc_ops
*ops
= qdisc
->ops
;
535 EXPORT_SYMBOL(qdisc_reset
);
537 void qdisc_destroy(struct Qdisc
*qdisc
)
539 const struct Qdisc_ops
*ops
= qdisc
->ops
;
541 if (qdisc
->flags
& TCQ_F_BUILTIN
||
542 !atomic_dec_and_test(&qdisc
->refcnt
))
545 #ifdef CONFIG_NET_SCHED
546 qdisc_list_del(qdisc
);
548 qdisc_put_stab(qdisc
->stab
);
550 gen_kill_estimator(&qdisc
->bstats
, &qdisc
->rate_est
);
556 module_put(ops
->owner
);
557 dev_put(qdisc_dev(qdisc
));
559 kfree_skb(qdisc
->gso_skb
);
560 __skb_queue_purge(&qdisc
->requeue
);
562 kfree((char *) qdisc
- qdisc
->padded
);
564 EXPORT_SYMBOL(qdisc_destroy
);
566 static bool dev_all_qdisc_sleeping_noop(struct net_device
*dev
)
570 for (i
= 0; i
< dev
->num_tx_queues
; i
++) {
571 struct netdev_queue
*txq
= netdev_get_tx_queue(dev
, i
);
573 if (txq
->qdisc_sleeping
!= &noop_qdisc
)
579 static void attach_one_default_qdisc(struct net_device
*dev
,
580 struct netdev_queue
*dev_queue
,
585 if (dev
->tx_queue_len
) {
586 qdisc
= qdisc_create_dflt(dev
, dev_queue
,
587 &pfifo_fast_ops
, TC_H_ROOT
);
589 printk(KERN_INFO
"%s: activation failed\n", dev
->name
);
593 qdisc
= &noqueue_qdisc
;
595 dev_queue
->qdisc_sleeping
= qdisc
;
598 static void transition_one_qdisc(struct net_device
*dev
,
599 struct netdev_queue
*dev_queue
,
600 void *_need_watchdog
)
602 struct Qdisc
*new_qdisc
= dev_queue
->qdisc_sleeping
;
603 int *need_watchdog_p
= _need_watchdog
;
605 if (!(new_qdisc
->flags
& TCQ_F_BUILTIN
))
606 clear_bit(__QDISC_STATE_DEACTIVATED
, &new_qdisc
->state
);
608 rcu_assign_pointer(dev_queue
->qdisc
, new_qdisc
);
609 if (need_watchdog_p
&& new_qdisc
!= &noqueue_qdisc
)
610 *need_watchdog_p
= 1;
613 void dev_activate(struct net_device
*dev
)
617 /* No queueing discipline is attached to device;
618 create default one i.e. pfifo_fast for devices,
619 which need queueing and noqueue_qdisc for
623 if (dev_all_qdisc_sleeping_noop(dev
))
624 netdev_for_each_tx_queue(dev
, attach_one_default_qdisc
, NULL
);
626 if (!netif_carrier_ok(dev
))
627 /* Delay activation until next carrier-on event */
631 netdev_for_each_tx_queue(dev
, transition_one_qdisc
, &need_watchdog
);
632 transition_one_qdisc(dev
, &dev
->rx_queue
, NULL
);
635 dev
->trans_start
= jiffies
;
636 dev_watchdog_up(dev
);
640 static void dev_deactivate_queue(struct net_device
*dev
,
641 struct netdev_queue
*dev_queue
,
642 void *_qdisc_default
)
644 struct Qdisc
*qdisc_default
= _qdisc_default
;
647 qdisc
= dev_queue
->qdisc
;
649 spin_lock_bh(qdisc_lock(qdisc
));
651 if (!(qdisc
->flags
& TCQ_F_BUILTIN
))
652 set_bit(__QDISC_STATE_DEACTIVATED
, &qdisc
->state
);
654 rcu_assign_pointer(dev_queue
->qdisc
, qdisc_default
);
657 spin_unlock_bh(qdisc_lock(qdisc
));
661 static bool some_qdisc_is_busy(struct net_device
*dev
)
665 for (i
= 0; i
< dev
->num_tx_queues
; i
++) {
666 struct netdev_queue
*dev_queue
;
667 spinlock_t
*root_lock
;
671 dev_queue
= netdev_get_tx_queue(dev
, i
);
672 q
= dev_queue
->qdisc_sleeping
;
673 root_lock
= qdisc_lock(q
);
675 spin_lock_bh(root_lock
);
677 val
= (test_bit(__QDISC_STATE_RUNNING
, &q
->state
) ||
678 test_bit(__QDISC_STATE_SCHED
, &q
->state
));
680 spin_unlock_bh(root_lock
);
688 void dev_deactivate(struct net_device
*dev
)
690 netdev_for_each_tx_queue(dev
, dev_deactivate_queue
, &noop_qdisc
);
691 dev_deactivate_queue(dev
, &dev
->rx_queue
, &noop_qdisc
);
693 dev_watchdog_down(dev
);
695 /* Wait for outstanding qdisc-less dev_queue_xmit calls. */
698 /* Wait for outstanding qdisc_run calls. */
699 while (some_qdisc_is_busy(dev
))
703 static void dev_init_scheduler_queue(struct net_device
*dev
,
704 struct netdev_queue
*dev_queue
,
707 struct Qdisc
*qdisc
= _qdisc
;
709 dev_queue
->qdisc
= qdisc
;
710 dev_queue
->qdisc_sleeping
= qdisc
;
713 void dev_init_scheduler(struct net_device
*dev
)
715 netdev_for_each_tx_queue(dev
, dev_init_scheduler_queue
, &noop_qdisc
);
716 dev_init_scheduler_queue(dev
, &dev
->rx_queue
, &noop_qdisc
);
718 setup_timer(&dev
->watchdog_timer
, dev_watchdog
, (unsigned long)dev
);
721 static void shutdown_scheduler_queue(struct net_device
*dev
,
722 struct netdev_queue
*dev_queue
,
723 void *_qdisc_default
)
725 struct Qdisc
*qdisc
= dev_queue
->qdisc_sleeping
;
726 struct Qdisc
*qdisc_default
= _qdisc_default
;
729 rcu_assign_pointer(dev_queue
->qdisc
, qdisc_default
);
730 dev_queue
->qdisc_sleeping
= qdisc_default
;
732 qdisc_destroy(qdisc
);
736 void dev_shutdown(struct net_device
*dev
)
738 netdev_for_each_tx_queue(dev
, shutdown_scheduler_queue
, &noop_qdisc
);
739 shutdown_scheduler_queue(dev
, &dev
->rx_queue
, &noop_qdisc
);
740 WARN_ON(timer_pending(&dev
->watchdog_timer
));