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
)
53 static inline struct sk_buff
*dequeue_skb(struct Qdisc
*q
)
55 struct sk_buff
*skb
= q
->gso_skb
;
58 struct net_device
*dev
= qdisc_dev(q
);
59 struct netdev_queue
*txq
;
61 /* check the reason of requeuing without tx lock first */
62 txq
= netdev_get_tx_queue(dev
, skb_get_queue_mapping(skb
));
63 if (!netif_tx_queue_stopped(txq
) && !netif_tx_queue_frozen(txq
))
74 static inline int handle_dev_cpu_collision(struct sk_buff
*skb
,
75 struct netdev_queue
*dev_queue
,
80 if (unlikely(dev_queue
->xmit_lock_owner
== smp_processor_id())) {
82 * Same CPU holding the lock. It may be a transient
83 * configuration error, when hard_start_xmit() recurses. We
84 * detect it by checking xmit owner and drop the packet when
85 * deadloop is detected. Return OK to try the next skb.
89 printk(KERN_WARNING
"Dead loop on netdevice %s, "
90 "fix it urgently!\n", dev_queue
->dev
->name
);
94 * Another cpu is holding lock, requeue & delay xmits for
97 __get_cpu_var(netdev_rx_stat
).cpu_collision
++;
98 ret
= dev_requeue_skb(skb
, q
);
105 * NOTE: Called under qdisc_lock(q) with locally disabled BH.
107 * __QDISC_STATE_RUNNING guarantees only one CPU can process
108 * this qdisc at a time. qdisc_lock(q) serializes queue accesses for
111 * netif_tx_lock serializes accesses to device driver.
113 * qdisc_lock(q) and netif_tx_lock are mutually exclusive,
114 * if one is grabbed, another must be free.
116 * Note, that this procedure can be called by a watchdog timer
118 * Returns to the caller:
119 * 0 - queue is empty or throttled.
120 * >0 - queue is not empty.
123 static inline int qdisc_restart(struct Qdisc
*q
)
125 struct netdev_queue
*txq
;
126 int ret
= NETDEV_TX_BUSY
;
127 struct net_device
*dev
;
128 spinlock_t
*root_lock
;
132 if (unlikely((skb
= dequeue_skb(q
)) == NULL
))
135 root_lock
= qdisc_lock(q
);
137 /* And release qdisc */
138 spin_unlock(root_lock
);
141 txq
= netdev_get_tx_queue(dev
, skb_get_queue_mapping(skb
));
143 HARD_TX_LOCK(dev
, txq
, smp_processor_id());
144 if (!netif_tx_queue_stopped(txq
) &&
145 !netif_tx_queue_frozen(txq
))
146 ret
= dev_hard_start_xmit(skb
, dev
, txq
);
147 HARD_TX_UNLOCK(dev
, txq
);
149 spin_lock(root_lock
);
153 /* Driver sent out skb successfully */
157 case NETDEV_TX_LOCKED
:
158 /* Driver try lock failed */
159 ret
= handle_dev_cpu_collision(skb
, txq
, q
);
163 /* Driver returned NETDEV_TX_BUSY - requeue skb */
164 if (unlikely (ret
!= NETDEV_TX_BUSY
&& net_ratelimit()))
165 printk(KERN_WARNING
"BUG %s code %d qlen %d\n",
166 dev
->name
, ret
, q
->q
.qlen
);
168 ret
= dev_requeue_skb(skb
, q
);
172 if (ret
&& (netif_tx_queue_stopped(txq
) ||
173 netif_tx_queue_frozen(txq
)))
179 void __qdisc_run(struct Qdisc
*q
)
181 unsigned long start_time
= jiffies
;
183 while (qdisc_restart(q
)) {
185 * Postpone processing if
186 * 1. another process needs the CPU;
187 * 2. we've been doing it for too long.
189 if (need_resched() || jiffies
!= start_time
) {
195 clear_bit(__QDISC_STATE_RUNNING
, &q
->state
);
198 static void dev_watchdog(unsigned long arg
)
200 struct net_device
*dev
= (struct net_device
*)arg
;
203 if (!qdisc_tx_is_noop(dev
)) {
204 if (netif_device_present(dev
) &&
205 netif_running(dev
) &&
206 netif_carrier_ok(dev
)) {
207 int some_queue_stopped
= 0;
210 for (i
= 0; i
< dev
->num_tx_queues
; i
++) {
211 struct netdev_queue
*txq
;
213 txq
= netdev_get_tx_queue(dev
, i
);
214 if (netif_tx_queue_stopped(txq
)) {
215 some_queue_stopped
= 1;
220 if (some_queue_stopped
&&
221 time_after(jiffies
, (dev
->trans_start
+
222 dev
->watchdog_timeo
))) {
224 WARN_ONCE(1, KERN_INFO
"NETDEV WATCHDOG: %s (%s): transmit timed out\n",
225 dev
->name
, netdev_drivername(dev
, drivername
, 64));
226 dev
->tx_timeout(dev
);
228 if (!mod_timer(&dev
->watchdog_timer
,
229 round_jiffies(jiffies
+
230 dev
->watchdog_timeo
)))
234 netif_tx_unlock(dev
);
239 void __netdev_watchdog_up(struct net_device
*dev
)
241 if (dev
->tx_timeout
) {
242 if (dev
->watchdog_timeo
<= 0)
243 dev
->watchdog_timeo
= 5*HZ
;
244 if (!mod_timer(&dev
->watchdog_timer
,
245 round_jiffies(jiffies
+ dev
->watchdog_timeo
)))
250 static void dev_watchdog_up(struct net_device
*dev
)
252 __netdev_watchdog_up(dev
);
255 static void dev_watchdog_down(struct net_device
*dev
)
257 netif_tx_lock_bh(dev
);
258 if (del_timer(&dev
->watchdog_timer
))
260 netif_tx_unlock_bh(dev
);
264 * netif_carrier_on - set carrier
265 * @dev: network device
267 * Device has detected that carrier.
269 void netif_carrier_on(struct net_device
*dev
)
271 if (test_and_clear_bit(__LINK_STATE_NOCARRIER
, &dev
->state
)) {
272 linkwatch_fire_event(dev
);
273 if (netif_running(dev
))
274 __netdev_watchdog_up(dev
);
277 EXPORT_SYMBOL(netif_carrier_on
);
280 * netif_carrier_off - clear carrier
281 * @dev: network device
283 * Device has detected loss of carrier.
285 void netif_carrier_off(struct net_device
*dev
)
287 if (!test_and_set_bit(__LINK_STATE_NOCARRIER
, &dev
->state
))
288 linkwatch_fire_event(dev
);
290 EXPORT_SYMBOL(netif_carrier_off
);
292 /* "NOOP" scheduler: the best scheduler, recommended for all interfaces
293 under all circumstances. It is difficult to invent anything faster or
297 static int noop_enqueue(struct sk_buff
*skb
, struct Qdisc
* qdisc
)
303 static struct sk_buff
*noop_dequeue(struct Qdisc
* qdisc
)
308 static int noop_requeue(struct sk_buff
*skb
, struct Qdisc
* qdisc
)
311 printk(KERN_DEBUG
"%s deferred output. It is buggy.\n",
317 struct Qdisc_ops noop_qdisc_ops __read_mostly
= {
320 .enqueue
= noop_enqueue
,
321 .dequeue
= noop_dequeue
,
322 .requeue
= noop_requeue
,
323 .owner
= THIS_MODULE
,
326 static struct netdev_queue noop_netdev_queue
= {
327 .qdisc
= &noop_qdisc
,
330 struct Qdisc noop_qdisc
= {
331 .enqueue
= noop_enqueue
,
332 .dequeue
= noop_dequeue
,
333 .flags
= TCQ_F_BUILTIN
,
334 .ops
= &noop_qdisc_ops
,
335 .list
= LIST_HEAD_INIT(noop_qdisc
.list
),
336 .requeue
.lock
= __SPIN_LOCK_UNLOCKED(noop_qdisc
.q
.lock
),
337 .q
.lock
= __SPIN_LOCK_UNLOCKED(noop_qdisc
.q
.lock
),
338 .dev_queue
= &noop_netdev_queue
,
340 EXPORT_SYMBOL(noop_qdisc
);
342 static struct Qdisc_ops noqueue_qdisc_ops __read_mostly
= {
345 .enqueue
= noop_enqueue
,
346 .dequeue
= noop_dequeue
,
347 .requeue
= noop_requeue
,
348 .owner
= THIS_MODULE
,
351 static struct Qdisc noqueue_qdisc
;
352 static struct netdev_queue noqueue_netdev_queue
= {
353 .qdisc
= &noqueue_qdisc
,
356 static struct Qdisc noqueue_qdisc
= {
358 .dequeue
= noop_dequeue
,
359 .flags
= TCQ_F_BUILTIN
,
360 .ops
= &noqueue_qdisc_ops
,
361 .list
= LIST_HEAD_INIT(noqueue_qdisc
.list
),
362 .requeue
.lock
= __SPIN_LOCK_UNLOCKED(noqueue_qdisc
.q
.lock
),
363 .q
.lock
= __SPIN_LOCK_UNLOCKED(noqueue_qdisc
.q
.lock
),
364 .dev_queue
= &noqueue_netdev_queue
,
368 static const u8 prio2band
[TC_PRIO_MAX
+1] =
369 { 1, 2, 2, 2, 1, 2, 0, 0 , 1, 1, 1, 1, 1, 1, 1, 1 };
371 /* 3-band FIFO queue: old style, but should be a bit faster than
372 generic prio+fifo combination.
375 #define PFIFO_FAST_BANDS 3
377 static inline struct sk_buff_head
*prio2list(struct sk_buff
*skb
,
380 struct sk_buff_head
*list
= qdisc_priv(qdisc
);
381 return list
+ prio2band
[skb
->priority
& TC_PRIO_MAX
];
384 static int pfifo_fast_enqueue(struct sk_buff
*skb
, struct Qdisc
* qdisc
)
386 struct sk_buff_head
*list
= prio2list(skb
, qdisc
);
388 if (skb_queue_len(list
) < qdisc_dev(qdisc
)->tx_queue_len
) {
390 return __qdisc_enqueue_tail(skb
, qdisc
, list
);
393 return qdisc_drop(skb
, qdisc
);
396 static struct sk_buff
*pfifo_fast_dequeue(struct Qdisc
* qdisc
)
399 struct sk_buff_head
*list
= qdisc_priv(qdisc
);
401 for (prio
= 0; prio
< PFIFO_FAST_BANDS
; prio
++) {
402 if (!skb_queue_empty(list
+ prio
)) {
404 return __qdisc_dequeue_head(qdisc
, list
+ prio
);
411 static int pfifo_fast_requeue(struct sk_buff
*skb
, struct Qdisc
* qdisc
)
414 return __qdisc_requeue(skb
, qdisc
, prio2list(skb
, qdisc
));
417 static void pfifo_fast_reset(struct Qdisc
* qdisc
)
420 struct sk_buff_head
*list
= qdisc_priv(qdisc
);
422 for (prio
= 0; prio
< PFIFO_FAST_BANDS
; prio
++)
423 __qdisc_reset_queue(qdisc
, list
+ prio
);
425 qdisc
->qstats
.backlog
= 0;
429 static int pfifo_fast_dump(struct Qdisc
*qdisc
, struct sk_buff
*skb
)
431 struct tc_prio_qopt opt
= { .bands
= PFIFO_FAST_BANDS
};
433 memcpy(&opt
.priomap
, prio2band
, TC_PRIO_MAX
+1);
434 NLA_PUT(skb
, TCA_OPTIONS
, sizeof(opt
), &opt
);
441 static int pfifo_fast_init(struct Qdisc
*qdisc
, struct nlattr
*opt
)
444 struct sk_buff_head
*list
= qdisc_priv(qdisc
);
446 for (prio
= 0; prio
< PFIFO_FAST_BANDS
; prio
++)
447 skb_queue_head_init(list
+ prio
);
452 static struct Qdisc_ops pfifo_fast_ops __read_mostly
= {
454 .priv_size
= PFIFO_FAST_BANDS
* sizeof(struct sk_buff_head
),
455 .enqueue
= pfifo_fast_enqueue
,
456 .dequeue
= pfifo_fast_dequeue
,
457 .requeue
= pfifo_fast_requeue
,
458 .init
= pfifo_fast_init
,
459 .reset
= pfifo_fast_reset
,
460 .dump
= pfifo_fast_dump
,
461 .owner
= THIS_MODULE
,
464 struct Qdisc
*qdisc_alloc(struct netdev_queue
*dev_queue
,
465 struct Qdisc_ops
*ops
)
472 /* ensure that the Qdisc and the private data are 32-byte aligned */
473 size
= QDISC_ALIGN(sizeof(*sch
));
474 size
+= ops
->priv_size
+ (QDISC_ALIGNTO
- 1);
476 p
= kzalloc(size
, GFP_KERNEL
);
479 sch
= (struct Qdisc
*) QDISC_ALIGN((unsigned long) p
);
480 sch
->padded
= (char *) sch
- (char *) p
;
482 INIT_LIST_HEAD(&sch
->list
);
483 skb_queue_head_init(&sch
->requeue
);
484 skb_queue_head_init(&sch
->q
);
486 sch
->enqueue
= ops
->enqueue
;
487 sch
->dequeue
= ops
->dequeue
;
488 sch
->dev_queue
= dev_queue
;
489 dev_hold(qdisc_dev(sch
));
490 atomic_set(&sch
->refcnt
, 1);
497 struct Qdisc
* qdisc_create_dflt(struct net_device
*dev
,
498 struct netdev_queue
*dev_queue
,
499 struct Qdisc_ops
*ops
,
500 unsigned int parentid
)
504 sch
= qdisc_alloc(dev_queue
, ops
);
507 sch
->parent
= parentid
;
509 if (!ops
->init
|| ops
->init(sch
, NULL
) == 0)
516 EXPORT_SYMBOL(qdisc_create_dflt
);
518 /* Under qdisc_lock(qdisc) and BH! */
520 void qdisc_reset(struct Qdisc
*qdisc
)
522 const struct Qdisc_ops
*ops
= qdisc
->ops
;
527 EXPORT_SYMBOL(qdisc_reset
);
529 void qdisc_destroy(struct Qdisc
*qdisc
)
531 const struct Qdisc_ops
*ops
= qdisc
->ops
;
533 if (qdisc
->flags
& TCQ_F_BUILTIN
||
534 !atomic_dec_and_test(&qdisc
->refcnt
))
537 #ifdef CONFIG_NET_SCHED
538 qdisc_list_del(qdisc
);
540 qdisc_put_stab(qdisc
->stab
);
542 gen_kill_estimator(&qdisc
->bstats
, &qdisc
->rate_est
);
548 module_put(ops
->owner
);
549 dev_put(qdisc_dev(qdisc
));
551 kfree_skb(qdisc
->gso_skb
);
552 __skb_queue_purge(&qdisc
->requeue
);
554 kfree((char *) qdisc
- qdisc
->padded
);
556 EXPORT_SYMBOL(qdisc_destroy
);
558 static bool dev_all_qdisc_sleeping_noop(struct net_device
*dev
)
562 for (i
= 0; i
< dev
->num_tx_queues
; i
++) {
563 struct netdev_queue
*txq
= netdev_get_tx_queue(dev
, i
);
565 if (txq
->qdisc_sleeping
!= &noop_qdisc
)
571 static void attach_one_default_qdisc(struct net_device
*dev
,
572 struct netdev_queue
*dev_queue
,
577 if (dev
->tx_queue_len
) {
578 qdisc
= qdisc_create_dflt(dev
, dev_queue
,
579 &pfifo_fast_ops
, TC_H_ROOT
);
581 printk(KERN_INFO
"%s: activation failed\n", dev
->name
);
585 qdisc
= &noqueue_qdisc
;
587 dev_queue
->qdisc_sleeping
= qdisc
;
590 static void transition_one_qdisc(struct net_device
*dev
,
591 struct netdev_queue
*dev_queue
,
592 void *_need_watchdog
)
594 struct Qdisc
*new_qdisc
= dev_queue
->qdisc_sleeping
;
595 int *need_watchdog_p
= _need_watchdog
;
597 if (!(new_qdisc
->flags
& TCQ_F_BUILTIN
))
598 clear_bit(__QDISC_STATE_DEACTIVATED
, &new_qdisc
->state
);
600 rcu_assign_pointer(dev_queue
->qdisc
, new_qdisc
);
601 if (need_watchdog_p
&& new_qdisc
!= &noqueue_qdisc
)
602 *need_watchdog_p
= 1;
605 void dev_activate(struct net_device
*dev
)
609 /* No queueing discipline is attached to device;
610 create default one i.e. pfifo_fast for devices,
611 which need queueing and noqueue_qdisc for
615 if (dev_all_qdisc_sleeping_noop(dev
))
616 netdev_for_each_tx_queue(dev
, attach_one_default_qdisc
, NULL
);
618 if (!netif_carrier_ok(dev
))
619 /* Delay activation until next carrier-on event */
623 netdev_for_each_tx_queue(dev
, transition_one_qdisc
, &need_watchdog
);
624 transition_one_qdisc(dev
, &dev
->rx_queue
, NULL
);
627 dev
->trans_start
= jiffies
;
628 dev_watchdog_up(dev
);
632 static void dev_deactivate_queue(struct net_device
*dev
,
633 struct netdev_queue
*dev_queue
,
634 void *_qdisc_default
)
636 struct Qdisc
*qdisc_default
= _qdisc_default
;
639 qdisc
= dev_queue
->qdisc
;
641 spin_lock_bh(qdisc_lock(qdisc
));
643 if (!(qdisc
->flags
& TCQ_F_BUILTIN
))
644 set_bit(__QDISC_STATE_DEACTIVATED
, &qdisc
->state
);
646 rcu_assign_pointer(dev_queue
->qdisc
, qdisc_default
);
649 spin_unlock_bh(qdisc_lock(qdisc
));
653 static bool some_qdisc_is_busy(struct net_device
*dev
)
657 for (i
= 0; i
< dev
->num_tx_queues
; i
++) {
658 struct netdev_queue
*dev_queue
;
659 spinlock_t
*root_lock
;
663 dev_queue
= netdev_get_tx_queue(dev
, i
);
664 q
= dev_queue
->qdisc_sleeping
;
665 root_lock
= qdisc_lock(q
);
667 spin_lock_bh(root_lock
);
669 val
= (test_bit(__QDISC_STATE_RUNNING
, &q
->state
) ||
670 test_bit(__QDISC_STATE_SCHED
, &q
->state
));
672 spin_unlock_bh(root_lock
);
680 void dev_deactivate(struct net_device
*dev
)
682 netdev_for_each_tx_queue(dev
, dev_deactivate_queue
, &noop_qdisc
);
683 dev_deactivate_queue(dev
, &dev
->rx_queue
, &noop_qdisc
);
685 dev_watchdog_down(dev
);
687 /* Wait for outstanding qdisc-less dev_queue_xmit calls. */
690 /* Wait for outstanding qdisc_run calls. */
691 while (some_qdisc_is_busy(dev
))
695 static void dev_init_scheduler_queue(struct net_device
*dev
,
696 struct netdev_queue
*dev_queue
,
699 struct Qdisc
*qdisc
= _qdisc
;
701 dev_queue
->qdisc
= qdisc
;
702 dev_queue
->qdisc_sleeping
= qdisc
;
705 void dev_init_scheduler(struct net_device
*dev
)
707 netdev_for_each_tx_queue(dev
, dev_init_scheduler_queue
, &noop_qdisc
);
708 dev_init_scheduler_queue(dev
, &dev
->rx_queue
, &noop_qdisc
);
710 setup_timer(&dev
->watchdog_timer
, dev_watchdog
, (unsigned long)dev
);
713 static void shutdown_scheduler_queue(struct net_device
*dev
,
714 struct netdev_queue
*dev_queue
,
715 void *_qdisc_default
)
717 struct Qdisc
*qdisc
= dev_queue
->qdisc_sleeping
;
718 struct Qdisc
*qdisc_default
= _qdisc_default
;
721 rcu_assign_pointer(dev_queue
->qdisc
, qdisc_default
);
722 dev_queue
->qdisc_sleeping
= qdisc_default
;
724 qdisc_destroy(qdisc
);
728 void dev_shutdown(struct net_device
*dev
)
730 netdev_for_each_tx_queue(dev
, shutdown_scheduler_queue
, &noop_qdisc
);
731 shutdown_scheduler_queue(dev
, &dev
->rx_queue
, &noop_qdisc
);
732 WARN_ON(timer_pending(&dev
->watchdog_timer
));