[PKT_SCHED] ematch: Fix build warning.
[linux-2.6] / net / sched / sch_generic.c
1 /*
2  * net/sched/sch_generic.c      Generic packet scheduler routines.
3  *
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.
8  *
9  * Authors:     Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
10  *              Jamal Hadi Salim, <hadi@cyberus.ca> 990601
11  *              - Ingress support
12  */
13
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>
28
29 /* Main transmission queue. */
30
31 /* Modifications to data participating in scheduling must be protected with
32  * dev->queue_lock spinlock.
33  *
34  * The idea is the following:
35  * - enqueue, dequeue are serialized via top level device
36  *   spinlock dev->queue_lock.
37  * - ingress filtering is serialized via top level device
38  *   spinlock dev->ingress_lock.
39  * - updates to tree and tree walking are only done under the rtnl mutex.
40  */
41
42 void qdisc_lock_tree(struct net_device *dev)
43         __acquires(dev->queue_lock)
44         __acquires(dev->ingress_lock)
45 {
46         spin_lock_bh(&dev->queue_lock);
47         spin_lock(&dev->ingress_lock);
48 }
49 EXPORT_SYMBOL(qdisc_lock_tree);
50
51 void qdisc_unlock_tree(struct net_device *dev)
52         __releases(dev->ingress_lock)
53         __releases(dev->queue_lock)
54 {
55         spin_unlock(&dev->ingress_lock);
56         spin_unlock_bh(&dev->queue_lock);
57 }
58 EXPORT_SYMBOL(qdisc_unlock_tree);
59
60 static inline int qdisc_qlen(struct Qdisc *q)
61 {
62         return q->q.qlen;
63 }
64
65 static inline int dev_requeue_skb(struct sk_buff *skb, struct net_device *dev,
66                                   struct Qdisc *q)
67 {
68         if (unlikely(skb->next))
69                 dev->gso_skb = skb;
70         else
71                 q->ops->requeue(skb, q);
72
73         netif_schedule(dev);
74         return 0;
75 }
76
77 static inline struct sk_buff *dev_dequeue_skb(struct net_device *dev,
78                                               struct Qdisc *q)
79 {
80         struct sk_buff *skb;
81
82         if ((skb = dev->gso_skb))
83                 dev->gso_skb = NULL;
84         else
85                 skb = q->dequeue(q);
86
87         return skb;
88 }
89
90 static inline int handle_dev_cpu_collision(struct sk_buff *skb,
91                                            struct net_device *dev,
92                                            struct Qdisc *q)
93 {
94         int ret;
95
96         if (unlikely(dev->xmit_lock_owner == smp_processor_id())) {
97                 /*
98                  * Same CPU holding the lock. It may be a transient
99                  * configuration error, when hard_start_xmit() recurses. We
100                  * detect it by checking xmit owner and drop the packet when
101                  * deadloop is detected. Return OK to try the next skb.
102                  */
103                 kfree_skb(skb);
104                 if (net_ratelimit())
105                         printk(KERN_WARNING "Dead loop on netdevice %s, "
106                                "fix it urgently!\n", dev->name);
107                 ret = qdisc_qlen(q);
108         } else {
109                 /*
110                  * Another cpu is holding lock, requeue & delay xmits for
111                  * some time.
112                  */
113                 __get_cpu_var(netdev_rx_stat).cpu_collision++;
114                 ret = dev_requeue_skb(skb, dev, q);
115         }
116
117         return ret;
118 }
119
120 /*
121  * NOTE: Called under dev->queue_lock with locally disabled BH.
122  *
123  * __LINK_STATE_QDISC_RUNNING guarantees only one CPU can process this
124  * device at a time. dev->queue_lock serializes queue accesses for
125  * this device AND dev->qdisc pointer itself.
126  *
127  *  netif_tx_lock serializes accesses to device driver.
128  *
129  *  dev->queue_lock and netif_tx_lock are mutually exclusive,
130  *  if one is grabbed, another must be free.
131  *
132  * Note, that this procedure can be called by a watchdog timer
133  *
134  * Returns to the caller:
135  *                              0  - queue is empty or throttled.
136  *                              >0 - queue is not empty.
137  *
138  */
139 static inline int qdisc_restart(struct net_device *dev)
140 {
141         struct Qdisc *q = dev->qdisc;
142         struct sk_buff *skb;
143         int ret = NETDEV_TX_BUSY;
144
145         /* Dequeue packet */
146         if (unlikely((skb = dev_dequeue_skb(dev, q)) == NULL))
147                 return 0;
148
149
150         /* And release queue */
151         spin_unlock(&dev->queue_lock);
152
153         HARD_TX_LOCK(dev, smp_processor_id());
154         if (!netif_subqueue_stopped(dev, skb))
155                 ret = dev_hard_start_xmit(skb, dev);
156         HARD_TX_UNLOCK(dev);
157
158         spin_lock(&dev->queue_lock);
159         q = dev->qdisc;
160
161         switch (ret) {
162         case NETDEV_TX_OK:
163                 /* Driver sent out skb successfully */
164                 ret = qdisc_qlen(q);
165                 break;
166
167         case NETDEV_TX_LOCKED:
168                 /* Driver try lock failed */
169                 ret = handle_dev_cpu_collision(skb, dev, q);
170                 break;
171
172         default:
173                 /* Driver returned NETDEV_TX_BUSY - requeue skb */
174                 if (unlikely (ret != NETDEV_TX_BUSY && net_ratelimit()))
175                         printk(KERN_WARNING "BUG %s code %d qlen %d\n",
176                                dev->name, ret, q->q.qlen);
177
178                 ret = dev_requeue_skb(skb, dev, q);
179                 break;
180         }
181
182         return ret;
183 }
184
185 void __qdisc_run(struct net_device *dev)
186 {
187         do {
188                 if (!qdisc_restart(dev))
189                         break;
190         } while (!netif_queue_stopped(dev));
191
192         clear_bit(__LINK_STATE_QDISC_RUNNING, &dev->state);
193 }
194
195 static void dev_watchdog(unsigned long arg)
196 {
197         struct net_device *dev = (struct net_device *)arg;
198
199         netif_tx_lock(dev);
200         if (dev->qdisc != &noop_qdisc) {
201                 if (netif_device_present(dev) &&
202                     netif_running(dev) &&
203                     netif_carrier_ok(dev)) {
204                         if (netif_queue_stopped(dev) &&
205                             time_after(jiffies, dev->trans_start + dev->watchdog_timeo)) {
206
207                                 printk(KERN_INFO "NETDEV WATCHDOG: %s: transmit timed out\n",
208                                        dev->name);
209                                 dev->tx_timeout(dev);
210                         }
211                         if (!mod_timer(&dev->watchdog_timer, round_jiffies(jiffies + dev->watchdog_timeo)))
212                                 dev_hold(dev);
213                 }
214         }
215         netif_tx_unlock(dev);
216
217         dev_put(dev);
218 }
219
220 void __netdev_watchdog_up(struct net_device *dev)
221 {
222         if (dev->tx_timeout) {
223                 if (dev->watchdog_timeo <= 0)
224                         dev->watchdog_timeo = 5*HZ;
225                 if (!mod_timer(&dev->watchdog_timer,
226                                round_jiffies(jiffies + dev->watchdog_timeo)))
227                         dev_hold(dev);
228         }
229 }
230
231 static void dev_watchdog_up(struct net_device *dev)
232 {
233         __netdev_watchdog_up(dev);
234 }
235
236 static void dev_watchdog_down(struct net_device *dev)
237 {
238         netif_tx_lock_bh(dev);
239         if (del_timer(&dev->watchdog_timer))
240                 dev_put(dev);
241         netif_tx_unlock_bh(dev);
242 }
243
244 /**
245  *      netif_carrier_on - set carrier
246  *      @dev: network device
247  *
248  * Device has detected that carrier.
249  */
250 void netif_carrier_on(struct net_device *dev)
251 {
252         if (test_and_clear_bit(__LINK_STATE_NOCARRIER, &dev->state)) {
253                 linkwatch_fire_event(dev);
254                 if (netif_running(dev))
255                         __netdev_watchdog_up(dev);
256         }
257 }
258 EXPORT_SYMBOL(netif_carrier_on);
259
260 /**
261  *      netif_carrier_off - clear carrier
262  *      @dev: network device
263  *
264  * Device has detected loss of carrier.
265  */
266 void netif_carrier_off(struct net_device *dev)
267 {
268         if (!test_and_set_bit(__LINK_STATE_NOCARRIER, &dev->state))
269                 linkwatch_fire_event(dev);
270 }
271 EXPORT_SYMBOL(netif_carrier_off);
272
273 /* "NOOP" scheduler: the best scheduler, recommended for all interfaces
274    under all circumstances. It is difficult to invent anything faster or
275    cheaper.
276  */
277
278 static int noop_enqueue(struct sk_buff *skb, struct Qdisc * qdisc)
279 {
280         kfree_skb(skb);
281         return NET_XMIT_CN;
282 }
283
284 static struct sk_buff *noop_dequeue(struct Qdisc * qdisc)
285 {
286         return NULL;
287 }
288
289 static int noop_requeue(struct sk_buff *skb, struct Qdisc* qdisc)
290 {
291         if (net_ratelimit())
292                 printk(KERN_DEBUG "%s deferred output. It is buggy.\n",
293                        skb->dev->name);
294         kfree_skb(skb);
295         return NET_XMIT_CN;
296 }
297
298 struct Qdisc_ops noop_qdisc_ops __read_mostly = {
299         .id             =       "noop",
300         .priv_size      =       0,
301         .enqueue        =       noop_enqueue,
302         .dequeue        =       noop_dequeue,
303         .requeue        =       noop_requeue,
304         .owner          =       THIS_MODULE,
305 };
306
307 struct Qdisc noop_qdisc = {
308         .enqueue        =       noop_enqueue,
309         .dequeue        =       noop_dequeue,
310         .flags          =       TCQ_F_BUILTIN,
311         .ops            =       &noop_qdisc_ops,
312         .list           =       LIST_HEAD_INIT(noop_qdisc.list),
313 };
314 EXPORT_SYMBOL(noop_qdisc);
315
316 static struct Qdisc_ops noqueue_qdisc_ops __read_mostly = {
317         .id             =       "noqueue",
318         .priv_size      =       0,
319         .enqueue        =       noop_enqueue,
320         .dequeue        =       noop_dequeue,
321         .requeue        =       noop_requeue,
322         .owner          =       THIS_MODULE,
323 };
324
325 static struct Qdisc noqueue_qdisc = {
326         .enqueue        =       NULL,
327         .dequeue        =       noop_dequeue,
328         .flags          =       TCQ_F_BUILTIN,
329         .ops            =       &noqueue_qdisc_ops,
330         .list           =       LIST_HEAD_INIT(noqueue_qdisc.list),
331 };
332
333
334 static const u8 prio2band[TC_PRIO_MAX+1] =
335         { 1, 2, 2, 2, 1, 2, 0, 0 , 1, 1, 1, 1, 1, 1, 1, 1 };
336
337 /* 3-band FIFO queue: old style, but should be a bit faster than
338    generic prio+fifo combination.
339  */
340
341 #define PFIFO_FAST_BANDS 3
342
343 static inline struct sk_buff_head *prio2list(struct sk_buff *skb,
344                                              struct Qdisc *qdisc)
345 {
346         struct sk_buff_head *list = qdisc_priv(qdisc);
347         return list + prio2band[skb->priority & TC_PRIO_MAX];
348 }
349
350 static int pfifo_fast_enqueue(struct sk_buff *skb, struct Qdisc* qdisc)
351 {
352         struct sk_buff_head *list = prio2list(skb, qdisc);
353
354         if (skb_queue_len(list) < qdisc->dev->tx_queue_len) {
355                 qdisc->q.qlen++;
356                 return __qdisc_enqueue_tail(skb, qdisc, list);
357         }
358
359         return qdisc_drop(skb, qdisc);
360 }
361
362 static struct sk_buff *pfifo_fast_dequeue(struct Qdisc* qdisc)
363 {
364         int prio;
365         struct sk_buff_head *list = qdisc_priv(qdisc);
366
367         for (prio = 0; prio < PFIFO_FAST_BANDS; prio++) {
368                 if (!skb_queue_empty(list + prio)) {
369                         qdisc->q.qlen--;
370                         return __qdisc_dequeue_head(qdisc, list + prio);
371                 }
372         }
373
374         return NULL;
375 }
376
377 static int pfifo_fast_requeue(struct sk_buff *skb, struct Qdisc* qdisc)
378 {
379         qdisc->q.qlen++;
380         return __qdisc_requeue(skb, qdisc, prio2list(skb, qdisc));
381 }
382
383 static void pfifo_fast_reset(struct Qdisc* qdisc)
384 {
385         int prio;
386         struct sk_buff_head *list = qdisc_priv(qdisc);
387
388         for (prio = 0; prio < PFIFO_FAST_BANDS; prio++)
389                 __qdisc_reset_queue(qdisc, list + prio);
390
391         qdisc->qstats.backlog = 0;
392         qdisc->q.qlen = 0;
393 }
394
395 static int pfifo_fast_dump(struct Qdisc *qdisc, struct sk_buff *skb)
396 {
397         struct tc_prio_qopt opt = { .bands = PFIFO_FAST_BANDS };
398
399         memcpy(&opt.priomap, prio2band, TC_PRIO_MAX+1);
400         NLA_PUT(skb, TCA_OPTIONS, sizeof(opt), &opt);
401         return skb->len;
402
403 nla_put_failure:
404         return -1;
405 }
406
407 static int pfifo_fast_init(struct Qdisc *qdisc, struct nlattr *opt)
408 {
409         int prio;
410         struct sk_buff_head *list = qdisc_priv(qdisc);
411
412         for (prio = 0; prio < PFIFO_FAST_BANDS; prio++)
413                 skb_queue_head_init(list + prio);
414
415         return 0;
416 }
417
418 static struct Qdisc_ops pfifo_fast_ops __read_mostly = {
419         .id             =       "pfifo_fast",
420         .priv_size      =       PFIFO_FAST_BANDS * sizeof(struct sk_buff_head),
421         .enqueue        =       pfifo_fast_enqueue,
422         .dequeue        =       pfifo_fast_dequeue,
423         .requeue        =       pfifo_fast_requeue,
424         .init           =       pfifo_fast_init,
425         .reset          =       pfifo_fast_reset,
426         .dump           =       pfifo_fast_dump,
427         .owner          =       THIS_MODULE,
428 };
429
430 struct Qdisc *qdisc_alloc(struct net_device *dev, struct Qdisc_ops *ops)
431 {
432         void *p;
433         struct Qdisc *sch;
434         unsigned int size;
435         int err = -ENOBUFS;
436
437         /* ensure that the Qdisc and the private data are 32-byte aligned */
438         size = QDISC_ALIGN(sizeof(*sch));
439         size += ops->priv_size + (QDISC_ALIGNTO - 1);
440
441         p = kzalloc(size, GFP_KERNEL);
442         if (!p)
443                 goto errout;
444         sch = (struct Qdisc *) QDISC_ALIGN((unsigned long) p);
445         sch->padded = (char *) sch - (char *) p;
446
447         INIT_LIST_HEAD(&sch->list);
448         skb_queue_head_init(&sch->q);
449         sch->ops = ops;
450         sch->enqueue = ops->enqueue;
451         sch->dequeue = ops->dequeue;
452         sch->dev = dev;
453         dev_hold(dev);
454         atomic_set(&sch->refcnt, 1);
455
456         return sch;
457 errout:
458         return ERR_PTR(-err);
459 }
460
461 struct Qdisc * qdisc_create_dflt(struct net_device *dev, struct Qdisc_ops *ops,
462                                  unsigned int parentid)
463 {
464         struct Qdisc *sch;
465
466         sch = qdisc_alloc(dev, ops);
467         if (IS_ERR(sch))
468                 goto errout;
469         sch->stats_lock = &dev->queue_lock;
470         sch->parent = parentid;
471
472         if (!ops->init || ops->init(sch, NULL) == 0)
473                 return sch;
474
475         qdisc_destroy(sch);
476 errout:
477         return NULL;
478 }
479 EXPORT_SYMBOL(qdisc_create_dflt);
480
481 /* Under dev->queue_lock and BH! */
482
483 void qdisc_reset(struct Qdisc *qdisc)
484 {
485         const struct Qdisc_ops *ops = qdisc->ops;
486
487         if (ops->reset)
488                 ops->reset(qdisc);
489 }
490 EXPORT_SYMBOL(qdisc_reset);
491
492 /* this is the rcu callback function to clean up a qdisc when there
493  * are no further references to it */
494
495 static void __qdisc_destroy(struct rcu_head *head)
496 {
497         struct Qdisc *qdisc = container_of(head, struct Qdisc, q_rcu);
498         kfree((char *) qdisc - qdisc->padded);
499 }
500
501 /* Under dev->queue_lock and BH! */
502
503 void qdisc_destroy(struct Qdisc *qdisc)
504 {
505         const struct Qdisc_ops  *ops = qdisc->ops;
506
507         if (qdisc->flags & TCQ_F_BUILTIN ||
508             !atomic_dec_and_test(&qdisc->refcnt))
509                 return;
510
511         list_del(&qdisc->list);
512         gen_kill_estimator(&qdisc->bstats, &qdisc->rate_est);
513         if (ops->reset)
514                 ops->reset(qdisc);
515         if (ops->destroy)
516                 ops->destroy(qdisc);
517
518         module_put(ops->owner);
519         dev_put(qdisc->dev);
520         call_rcu(&qdisc->q_rcu, __qdisc_destroy);
521 }
522 EXPORT_SYMBOL(qdisc_destroy);
523
524 void dev_activate(struct net_device *dev)
525 {
526         /* No queueing discipline is attached to device;
527            create default one i.e. pfifo_fast for devices,
528            which need queueing and noqueue_qdisc for
529            virtual interfaces
530          */
531
532         if (dev->qdisc_sleeping == &noop_qdisc) {
533                 struct Qdisc *qdisc;
534                 if (dev->tx_queue_len) {
535                         qdisc = qdisc_create_dflt(dev, &pfifo_fast_ops,
536                                                   TC_H_ROOT);
537                         if (qdisc == NULL) {
538                                 printk(KERN_INFO "%s: activation failed\n", dev->name);
539                                 return;
540                         }
541                         list_add_tail(&qdisc->list, &dev->qdisc_list);
542                 } else {
543                         qdisc =  &noqueue_qdisc;
544                 }
545                 dev->qdisc_sleeping = qdisc;
546         }
547
548         if (!netif_carrier_ok(dev))
549                 /* Delay activation until next carrier-on event */
550                 return;
551
552         spin_lock_bh(&dev->queue_lock);
553         rcu_assign_pointer(dev->qdisc, dev->qdisc_sleeping);
554         if (dev->qdisc != &noqueue_qdisc) {
555                 dev->trans_start = jiffies;
556                 dev_watchdog_up(dev);
557         }
558         spin_unlock_bh(&dev->queue_lock);
559 }
560
561 void dev_deactivate(struct net_device *dev)
562 {
563         struct Qdisc *qdisc;
564         struct sk_buff *skb;
565         int running;
566
567         spin_lock_bh(&dev->queue_lock);
568         qdisc = dev->qdisc;
569         dev->qdisc = &noop_qdisc;
570
571         qdisc_reset(qdisc);
572
573         skb = dev->gso_skb;
574         dev->gso_skb = NULL;
575         spin_unlock_bh(&dev->queue_lock);
576
577         kfree_skb(skb);
578
579         dev_watchdog_down(dev);
580
581         /* Wait for outstanding qdisc-less dev_queue_xmit calls. */
582         synchronize_rcu();
583
584         /* Wait for outstanding qdisc_run calls. */
585         do {
586                 while (test_bit(__LINK_STATE_QDISC_RUNNING, &dev->state))
587                         yield();
588
589                 /*
590                  * Double-check inside queue lock to ensure that all effects
591                  * of the queue run are visible when we return.
592                  */
593                 spin_lock_bh(&dev->queue_lock);
594                 running = test_bit(__LINK_STATE_QDISC_RUNNING, &dev->state);
595                 spin_unlock_bh(&dev->queue_lock);
596
597                 /*
598                  * The running flag should never be set at this point because
599                  * we've already set dev->qdisc to noop_qdisc *inside* the same
600                  * pair of spin locks.  That is, if any qdisc_run starts after
601                  * our initial test it should see the noop_qdisc and then
602                  * clear the RUNNING bit before dropping the queue lock.  So
603                  * if it is set here then we've found a bug.
604                  */
605         } while (WARN_ON_ONCE(running));
606 }
607
608 void dev_init_scheduler(struct net_device *dev)
609 {
610         qdisc_lock_tree(dev);
611         dev->qdisc = &noop_qdisc;
612         dev->qdisc_sleeping = &noop_qdisc;
613         INIT_LIST_HEAD(&dev->qdisc_list);
614         qdisc_unlock_tree(dev);
615
616         setup_timer(&dev->watchdog_timer, dev_watchdog, (unsigned long)dev);
617 }
618
619 void dev_shutdown(struct net_device *dev)
620 {
621         struct Qdisc *qdisc;
622
623         qdisc_lock_tree(dev);
624         qdisc = dev->qdisc_sleeping;
625         dev->qdisc = &noop_qdisc;
626         dev->qdisc_sleeping = &noop_qdisc;
627         qdisc_destroy(qdisc);
628 #if defined(CONFIG_NET_SCH_INGRESS) || defined(CONFIG_NET_SCH_INGRESS_MODULE)
629         if ((qdisc = dev->qdisc_ingress) != NULL) {
630                 dev->qdisc_ingress = NULL;
631                 qdisc_destroy(qdisc);
632         }
633 #endif
634         BUG_TRAP(!timer_pending(&dev->watchdog_timer));
635         qdisc_unlock_tree(dev);
636 }