neighbour.c 65.9 KB
Newer Older
Linus Torvalds's avatar
Linus Torvalds committed
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
/*
 *	Generic address resolution entity
 *
 *	Authors:
 *	Pedro Roque		<roque@di.fc.ul.pt>
 *	Alexey Kuznetsov	<kuznet@ms2.inr.ac.ru>
 *
 *	This program is free software; you can redistribute it and/or
 *      modify it under the terms of the GNU General Public License
 *      as published by the Free Software Foundation; either version
 *      2 of the License, or (at your option) any later version.
 *
 *	Fixes:
 *	Vitaly E. Lavrov	releasing NULL neighbor in neigh_add.
 *	Harald Welte		Add neighbour cache statistics like rtstat
 */

#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/socket.h>
#include <linux/netdevice.h>
#include <linux/proc_fs.h>
#ifdef CONFIG_SYSCTL
#include <linux/sysctl.h>
#endif
#include <linux/times.h>
28
#include <net/net_namespace.h>
Linus Torvalds's avatar
Linus Torvalds committed
29
30
31
#include <net/neighbour.h>
#include <net/dst.h>
#include <net/sock.h>
32
#include <net/netevent.h>
33
#include <net/netlink.h>
Linus Torvalds's avatar
Linus Torvalds committed
34
35
#include <linux/rtnetlink.h>
#include <linux/random.h>
36
#include <linux/string.h>
37
#include <linux/log2.h>
Linus Torvalds's avatar
Linus Torvalds committed
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58

#define NEIGH_DEBUG 1

#define NEIGH_PRINTK(x...) printk(x)
#define NEIGH_NOPRINTK(x...) do { ; } while(0)
#define NEIGH_PRINTK0 NEIGH_PRINTK
#define NEIGH_PRINTK1 NEIGH_NOPRINTK
#define NEIGH_PRINTK2 NEIGH_NOPRINTK

#if NEIGH_DEBUG >= 1
#undef NEIGH_PRINTK1
#define NEIGH_PRINTK1 NEIGH_PRINTK
#endif
#if NEIGH_DEBUG >= 2
#undef NEIGH_PRINTK2
#define NEIGH_PRINTK2 NEIGH_PRINTK
#endif

#define PNEIGH_HASHMASK		0xF

static void neigh_timer_handler(unsigned long arg);
Thomas Graf's avatar
Thomas Graf committed
59
60
static void __neigh_notify(struct neighbour *n, int type, int flags);
static void neigh_update_notify(struct neighbour *neigh);
Linus Torvalds's avatar
Linus Torvalds committed
61
62
63
static int pneigh_ifdown(struct neigh_table *tbl, struct net_device *dev);

static struct neigh_table *neigh_tables;
64
#ifdef CONFIG_PROC_FS
65
static const struct file_operations neigh_stat_seq_fops;
66
#endif
Linus Torvalds's avatar
Linus Torvalds committed
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106

/*
   Neighbour hash table buckets are protected with rwlock tbl->lock.

   - All the scans/updates to hash buckets MUST be made under this lock.
   - NOTHING clever should be made under this lock: no callbacks
     to protocol backends, no attempts to send something to network.
     It will result in deadlocks, if backend/driver wants to use neighbour
     cache.
   - If the entry requires some non-trivial actions, increase
     its reference count and release table lock.

   Neighbour entries are protected:
   - with reference count.
   - with rwlock neigh->lock

   Reference count prevents destruction.

   neigh->lock mainly serializes ll address data and its validity state.
   However, the same lock is used to protect another entry fields:
    - timer
    - resolution queue

   Again, nothing clever shall be made under neigh->lock,
   the most complicated procedure, which we allow is dev->hard_header.
   It is supposed, that dev->hard_header is simplistic and does
   not make callbacks to neighbour tables.

   The last lock is neigh_tbl_lock. It is pure SMP lock, protecting
   list of neighbour tables. This list is used only in process context,
 */

static DEFINE_RWLOCK(neigh_tbl_lock);

static int neigh_blackhole(struct sk_buff *skb)
{
	kfree_skb(skb);
	return -ENETDOWN;
}

107
108
109
110
111
static void neigh_cleanup_and_release(struct neighbour *neigh)
{
	if (neigh->parms->neigh_cleanup)
		neigh->parms->neigh_cleanup(neigh);

Thomas Graf's avatar
Thomas Graf committed
112
	__neigh_notify(neigh, RTM_DELNEIGH, 0);
113
114
115
	neigh_release(neigh);
}

Linus Torvalds's avatar
Linus Torvalds committed
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
/*
 * It is random distribution in the interval (1/2)*base...(3/2)*base.
 * It corresponds to default IPv6 settings and is not overridable,
 * because it is really reasonable choice.
 */

unsigned long neigh_rand_reach_time(unsigned long base)
{
	return (base ? (net_random() % base) + (base >> 1) : 0);
}


static int neigh_forced_gc(struct neigh_table *tbl)
{
	int shrunk = 0;
	int i;

	NEIGH_CACHE_STAT_INC(tbl, forced_gc_runs);

	write_lock_bh(&tbl->lock);
	for (i = 0; i <= tbl->hash_mask; i++) {
		struct neighbour *n, **np;

		np = &tbl->hash_buckets[i];
		while ((n = *np) != NULL) {
			/* Neighbour record may be discarded if:
			 * - nobody refers to it.
			 * - it is not permanent
			 */
			write_lock(&n->lock);
			if (atomic_read(&n->refcnt) == 1 &&
			    !(n->nud_state & NUD_PERMANENT)) {
				*np	= n->next;
				n->dead = 1;
				shrunk	= 1;
				write_unlock(&n->lock);
152
				neigh_cleanup_and_release(n);
Linus Torvalds's avatar
Linus Torvalds committed
153
154
155
156
157
158
159
160
161
162
163
164
165
166
				continue;
			}
			write_unlock(&n->lock);
			np = &n->next;
		}
	}

	tbl->last_flush = jiffies;

	write_unlock_bh(&tbl->lock);

	return shrunk;
}

167
168
169
170
171
172
173
174
175
176
static void neigh_add_timer(struct neighbour *n, unsigned long when)
{
	neigh_hold(n);
	if (unlikely(mod_timer(&n->timer, when))) {
		printk("NEIGH: BUG, double timer add, state is %x\n",
		       n->nud_state);
		dump_stack();
	}
}

Linus Torvalds's avatar
Linus Torvalds committed
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
static int neigh_del_timer(struct neighbour *n)
{
	if ((n->nud_state & NUD_IN_TIMER) &&
	    del_timer(&n->timer)) {
		neigh_release(n);
		return 1;
	}
	return 0;
}

static void pneigh_queue_purge(struct sk_buff_head *list)
{
	struct sk_buff *skb;

	while ((skb = skb_dequeue(list)) != NULL) {
		dev_put(skb->dev);
		kfree_skb(skb);
	}
}

197
static void neigh_flush_dev(struct neigh_table *tbl, struct net_device *dev)
Linus Torvalds's avatar
Linus Torvalds committed
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
{
	int i;

	for (i = 0; i <= tbl->hash_mask; i++) {
		struct neighbour *n, **np = &tbl->hash_buckets[i];

		while ((n = *np) != NULL) {
			if (dev && n->dev != dev) {
				np = &n->next;
				continue;
			}
			*np = n->next;
			write_lock(&n->lock);
			neigh_del_timer(n);
			n->dead = 1;

			if (atomic_read(&n->refcnt) != 1) {
				/* The most unpleasant situation.
				   We must destroy neighbour entry,
				   but someone still uses it.

				   The destroy will be delayed until
				   the last user releases us, but
				   we must kill timers etc. and move
				   it to safe state.
				 */
				skb_queue_purge(&n->arp_queue);
				n->output = neigh_blackhole;
				if (n->nud_state & NUD_VALID)
					n->nud_state = NUD_NOARP;
				else
					n->nud_state = NUD_NONE;
				NEIGH_PRINTK2("neigh %p is stray.\n", n);
			}
			write_unlock(&n->lock);
233
			neigh_cleanup_and_release(n);
Linus Torvalds's avatar
Linus Torvalds committed
234
235
		}
	}
236
}
Linus Torvalds's avatar
Linus Torvalds committed
237

238
239
240
241
242
243
244
245
246
247
248
void neigh_changeaddr(struct neigh_table *tbl, struct net_device *dev)
{
	write_lock_bh(&tbl->lock);
	neigh_flush_dev(tbl, dev);
	write_unlock_bh(&tbl->lock);
}

int neigh_ifdown(struct neigh_table *tbl, struct net_device *dev)
{
	write_lock_bh(&tbl->lock);
	neigh_flush_dev(tbl, dev);
Linus Torvalds's avatar
Linus Torvalds committed
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
	pneigh_ifdown(tbl, dev);
	write_unlock_bh(&tbl->lock);

	del_timer_sync(&tbl->proxy_timer);
	pneigh_queue_purge(&tbl->proxy_queue);
	return 0;
}

static struct neighbour *neigh_alloc(struct neigh_table *tbl)
{
	struct neighbour *n = NULL;
	unsigned long now = jiffies;
	int entries;

	entries = atomic_inc_return(&tbl->entries) - 1;
	if (entries >= tbl->gc_thresh3 ||
	    (entries >= tbl->gc_thresh2 &&
	     time_after(now, tbl->last_flush + 5 * HZ))) {
		if (!neigh_forced_gc(tbl) &&
		    entries >= tbl->gc_thresh3)
			goto out_entries;
	}

272
	n = kmem_cache_zalloc(tbl->kmem_cachep, GFP_ATOMIC);
Linus Torvalds's avatar
Linus Torvalds committed
273
274
275
276
277
278
279
280
281
	if (!n)
		goto out_entries;

	skb_queue_head_init(&n->arp_queue);
	rwlock_init(&n->lock);
	n->updated	  = n->used = now;
	n->nud_state	  = NUD_NONE;
	n->output	  = neigh_blackhole;
	n->parms	  = neigh_parms_clone(&tbl->parms);
282
	setup_timer(&n->timer, neigh_timer_handler, (unsigned long)n);
Linus Torvalds's avatar
Linus Torvalds committed
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301

	NEIGH_CACHE_STAT_INC(tbl, allocs);
	n->tbl		  = tbl;
	atomic_set(&n->refcnt, 1);
	n->dead		  = 1;
out:
	return n;

out_entries:
	atomic_dec(&tbl->entries);
	goto out;
}

static struct neighbour **neigh_hash_alloc(unsigned int entries)
{
	unsigned long size = entries * sizeof(struct neighbour *);
	struct neighbour **ret;

	if (size <= PAGE_SIZE) {
302
		ret = kzalloc(size, GFP_ATOMIC);
Linus Torvalds's avatar
Linus Torvalds committed
303
304
	} else {
		ret = (struct neighbour **)
305
		      __get_free_pages(GFP_ATOMIC|__GFP_ZERO, get_order(size));
Linus Torvalds's avatar
Linus Torvalds committed
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
	}
	return ret;
}

static void neigh_hash_free(struct neighbour **hash, unsigned int entries)
{
	unsigned long size = entries * sizeof(struct neighbour *);

	if (size <= PAGE_SIZE)
		kfree(hash);
	else
		free_pages((unsigned long)hash, get_order(size));
}

static void neigh_hash_grow(struct neigh_table *tbl, unsigned long new_entries)
{
	struct neighbour **new_hash, **old_hash;
	unsigned int i, new_hash_mask, old_entries;

	NEIGH_CACHE_STAT_INC(tbl, hash_grows);

327
	BUG_ON(!is_power_of_2(new_entries));
Linus Torvalds's avatar
Linus Torvalds committed
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
	new_hash = neigh_hash_alloc(new_entries);
	if (!new_hash)
		return;

	old_entries = tbl->hash_mask + 1;
	new_hash_mask = new_entries - 1;
	old_hash = tbl->hash_buckets;

	get_random_bytes(&tbl->hash_rnd, sizeof(tbl->hash_rnd));
	for (i = 0; i < old_entries; i++) {
		struct neighbour *n, *next;

		for (n = old_hash[i]; n; n = next) {
			unsigned int hash_val = tbl->hash(n->primary_key, n->dev);

			hash_val &= new_hash_mask;
			next = n->next;

			n->next = new_hash[hash_val];
			new_hash[hash_val] = n;
		}
	}
	tbl->hash_buckets = new_hash;
	tbl->hash_mask = new_hash_mask;

	neigh_hash_free(old_hash, old_entries);
}

struct neighbour *neigh_lookup(struct neigh_table *tbl, const void *pkey,
			       struct net_device *dev)
{
	struct neighbour *n;
	int key_len = tbl->key_len;
361
	u32 hash_val = tbl->hash(pkey, dev);
362

Linus Torvalds's avatar
Linus Torvalds committed
363
364
365
	NEIGH_CACHE_STAT_INC(tbl, lookups);

	read_lock_bh(&tbl->lock);
366
	for (n = tbl->hash_buckets[hash_val & tbl->hash_mask]; n; n = n->next) {
Linus Torvalds's avatar
Linus Torvalds committed
367
368
369
370
371
372
373
374
375
376
		if (dev == n->dev && !memcmp(n->primary_key, pkey, key_len)) {
			neigh_hold(n);
			NEIGH_CACHE_STAT_INC(tbl, hits);
			break;
		}
	}
	read_unlock_bh(&tbl->lock);
	return n;
}

377
378
struct neighbour *neigh_lookup_nodev(struct neigh_table *tbl, struct net *net,
				     const void *pkey)
Linus Torvalds's avatar
Linus Torvalds committed
379
380
381
{
	struct neighbour *n;
	int key_len = tbl->key_len;
382
	u32 hash_val = tbl->hash(pkey, NULL);
Linus Torvalds's avatar
Linus Torvalds committed
383
384
385
386

	NEIGH_CACHE_STAT_INC(tbl, lookups);

	read_lock_bh(&tbl->lock);
387
	for (n = tbl->hash_buckets[hash_val & tbl->hash_mask]; n; n = n->next) {
388
389
		if (!memcmp(n->primary_key, pkey, key_len) &&
		    (net == n->dev->nd_net)) {
Linus Torvalds's avatar
Linus Torvalds committed
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
			neigh_hold(n);
			NEIGH_CACHE_STAT_INC(tbl, hits);
			break;
		}
	}
	read_unlock_bh(&tbl->lock);
	return n;
}

struct neighbour *neigh_create(struct neigh_table *tbl, const void *pkey,
			       struct net_device *dev)
{
	u32 hash_val;
	int key_len = tbl->key_len;
	int error;
	struct neighbour *n1, *rc, *n = neigh_alloc(tbl);

	if (!n) {
		rc = ERR_PTR(-ENOBUFS);
		goto out;
	}

	memcpy(n->primary_key, pkey, key_len);
	n->dev = dev;
	dev_hold(dev);

	/* Protocol specific setup. */
	if (tbl->constructor &&	(error = tbl->constructor(n)) < 0) {
		rc = ERR_PTR(error);
		goto out_neigh_release;
	}

	/* Device specific setup. */
	if (n->parms->neigh_setup &&
	    (error = n->parms->neigh_setup(n)) < 0) {
		rc = ERR_PTR(error);
		goto out_neigh_release;
	}

	n->confirmed = jiffies - (n->parms->base_reachable_time << 1);

	write_lock_bh(&tbl->lock);

	if (atomic_read(&tbl->entries) > (tbl->hash_mask + 1))
		neigh_hash_grow(tbl, (tbl->hash_mask + 1) << 1);

	hash_val = tbl->hash(pkey, dev) & tbl->hash_mask;

	if (n->parms->dead) {
		rc = ERR_PTR(-EINVAL);
		goto out_tbl_unlock;
	}

	for (n1 = tbl->hash_buckets[hash_val]; n1; n1 = n1->next) {
		if (dev == n1->dev && !memcmp(n1->primary_key, pkey, key_len)) {
			neigh_hold(n1);
			rc = n1;
			goto out_tbl_unlock;
		}
	}

	n->next = tbl->hash_buckets[hash_val];
	tbl->hash_buckets[hash_val] = n;
	n->dead = 0;
	neigh_hold(n);
	write_unlock_bh(&tbl->lock);
	NEIGH_PRINTK2("neigh %p is created.\n", n);
	rc = n;
out:
	return rc;
out_tbl_unlock:
	write_unlock_bh(&tbl->lock);
out_neigh_release:
	neigh_release(n);
	goto out;
}

467
468
struct pneigh_entry * pneigh_lookup(struct neigh_table *tbl,
				    struct net *net, const void *pkey,
Linus Torvalds's avatar
Linus Torvalds committed
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
				    struct net_device *dev, int creat)
{
	struct pneigh_entry *n;
	int key_len = tbl->key_len;
	u32 hash_val = *(u32 *)(pkey + key_len - 4);

	hash_val ^= (hash_val >> 16);
	hash_val ^= hash_val >> 8;
	hash_val ^= hash_val >> 4;
	hash_val &= PNEIGH_HASHMASK;

	read_lock_bh(&tbl->lock);

	for (n = tbl->phash_buckets[hash_val]; n; n = n->next) {
		if (!memcmp(n->key, pkey, key_len) &&
484
		    (n->net == net) &&
Linus Torvalds's avatar
Linus Torvalds committed
485
486
487
488
489
490
491
492
493
494
		    (n->dev == dev || !n->dev)) {
			read_unlock_bh(&tbl->lock);
			goto out;
		}
	}
	read_unlock_bh(&tbl->lock);
	n = NULL;
	if (!creat)
		goto out;

495
496
	ASSERT_RTNL();

Linus Torvalds's avatar
Linus Torvalds committed
497
498
499
500
	n = kmalloc(sizeof(*n) + key_len, GFP_KERNEL);
	if (!n)
		goto out;

501
	n->net = hold_net(net);
Linus Torvalds's avatar
Linus Torvalds committed
502
503
504
505
506
507
508
509
	memcpy(n->key, pkey, key_len);
	n->dev = dev;
	if (dev)
		dev_hold(dev);

	if (tbl->pconstructor && tbl->pconstructor(n)) {
		if (dev)
			dev_put(dev);
510
		release_net(net);
Linus Torvalds's avatar
Linus Torvalds committed
511
512
513
514
515
516
517
518
519
520
521
522
523
524
		kfree(n);
		n = NULL;
		goto out;
	}

	write_lock_bh(&tbl->lock);
	n->next = tbl->phash_buckets[hash_val];
	tbl->phash_buckets[hash_val] = n;
	write_unlock_bh(&tbl->lock);
out:
	return n;
}


525
int pneigh_delete(struct neigh_table *tbl, struct net *net, const void *pkey,
Linus Torvalds's avatar
Linus Torvalds committed
526
527
528
529
530
531
532
533
534
535
536
537
538
539
		  struct net_device *dev)
{
	struct pneigh_entry *n, **np;
	int key_len = tbl->key_len;
	u32 hash_val = *(u32 *)(pkey + key_len - 4);

	hash_val ^= (hash_val >> 16);
	hash_val ^= hash_val >> 8;
	hash_val ^= hash_val >> 4;
	hash_val &= PNEIGH_HASHMASK;

	write_lock_bh(&tbl->lock);
	for (np = &tbl->phash_buckets[hash_val]; (n = *np) != NULL;
	     np = &n->next) {
540
541
		if (!memcmp(n->key, pkey, key_len) && n->dev == dev &&
		    (n->net == net)) {
Linus Torvalds's avatar
Linus Torvalds committed
542
543
544
545
546
547
			*np = n->next;
			write_unlock_bh(&tbl->lock);
			if (tbl->pdestructor)
				tbl->pdestructor(n);
			if (n->dev)
				dev_put(n->dev);
548
			release_net(n->net);
Linus Torvalds's avatar
Linus Torvalds committed
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
			kfree(n);
			return 0;
		}
	}
	write_unlock_bh(&tbl->lock);
	return -ENOENT;
}

static int pneigh_ifdown(struct neigh_table *tbl, struct net_device *dev)
{
	struct pneigh_entry *n, **np;
	u32 h;

	for (h = 0; h <= PNEIGH_HASHMASK; h++) {
		np = &tbl->phash_buckets[h];
		while ((n = *np) != NULL) {
			if (!dev || n->dev == dev) {
				*np = n->next;
				if (tbl->pdestructor)
					tbl->pdestructor(n);
				if (n->dev)
					dev_put(n->dev);
571
				release_net(n->net);
Linus Torvalds's avatar
Linus Torvalds committed
572
573
574
575
576
577
578
579
580
				kfree(n);
				continue;
			}
			np = &n->next;
		}
	}
	return -ENOENT;
}

581
582
583
584
585
586
587
static void neigh_parms_destroy(struct neigh_parms *parms);

static inline void neigh_parms_put(struct neigh_parms *parms)
{
	if (atomic_dec_and_test(&parms->refcnt))
		neigh_parms_destroy(parms);
}
Linus Torvalds's avatar
Linus Torvalds committed
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611

/*
 *	neighbour must already be out of the table;
 *
 */
void neigh_destroy(struct neighbour *neigh)
{
	struct hh_cache *hh;

	NEIGH_CACHE_STAT_INC(neigh->tbl, destroys);

	if (!neigh->dead) {
		printk(KERN_WARNING
		       "Destroying alive neighbour %p\n", neigh);
		dump_stack();
		return;
	}

	if (neigh_del_timer(neigh))
		printk(KERN_WARNING "Impossible event.\n");

	while ((hh = neigh->hh) != NULL) {
		neigh->hh = hh->hh_next;
		hh->hh_next = NULL;
612
613

		write_seqlock_bh(&hh->hh_lock);
Linus Torvalds's avatar
Linus Torvalds committed
614
		hh->hh_output = neigh_blackhole;
615
		write_sequnlock_bh(&hh->hh_lock);
Linus Torvalds's avatar
Linus Torvalds committed
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
		if (atomic_dec_and_test(&hh->hh_refcnt))
			kfree(hh);
	}

	skb_queue_purge(&neigh->arp_queue);

	dev_put(neigh->dev);
	neigh_parms_put(neigh->parms);

	NEIGH_PRINTK2("neigh %p is destroyed.\n", neigh);

	atomic_dec(&neigh->tbl->entries);
	kmem_cache_free(neigh->tbl->kmem_cachep, neigh);
}

/* Neighbour state is suspicious;
   disable fast path.

   Called with write_locked neigh.
 */
static void neigh_suspect(struct neighbour *neigh)
{
	struct hh_cache *hh;

	NEIGH_PRINTK2("neigh %p is suspected.\n", neigh);

	neigh->output = neigh->ops->output;

	for (hh = neigh->hh; hh; hh = hh->hh_next)
		hh->hh_output = neigh->ops->output;
}

/* Neighbour state is OK;
   enable fast path.

   Called with write_locked neigh.
 */
static void neigh_connect(struct neighbour *neigh)
{
	struct hh_cache *hh;

	NEIGH_PRINTK2("neigh %p is connected.\n", neigh);

	neigh->output = neigh->ops->connected_output;

	for (hh = neigh->hh; hh; hh = hh->hh_next)
		hh->hh_output = neigh->ops->hh_output;
}

static void neigh_periodic_timer(unsigned long arg)
{
	struct neigh_table *tbl = (struct neigh_table *)arg;
	struct neighbour *n, **np;
	unsigned long expire, now = jiffies;

	NEIGH_CACHE_STAT_INC(tbl, periodic_gc_runs);

	write_lock(&tbl->lock);

	/*
	 *	periodically recompute ReachableTime from random function
	 */

	if (time_after(now, tbl->last_rand + 300 * HZ)) {
		struct neigh_parms *p;
		tbl->last_rand = now;
		for (p = &tbl->parms; p; p = p->next)
			p->reachable_time =
				neigh_rand_reach_time(p->base_reachable_time);
	}

	np = &tbl->hash_buckets[tbl->hash_chain_gc];
	tbl->hash_chain_gc = ((tbl->hash_chain_gc + 1) & tbl->hash_mask);

	while ((n = *np) != NULL) {
		unsigned int state;

		write_lock(&n->lock);

		state = n->nud_state;
		if (state & (NUD_PERMANENT | NUD_IN_TIMER)) {
			write_unlock(&n->lock);
			goto next_elt;
		}

		if (time_before(n->used, n->confirmed))
			n->used = n->confirmed;

		if (atomic_read(&n->refcnt) == 1 &&
		    (state == NUD_FAILED ||
		     time_after(now, n->used + n->parms->gc_staletime))) {
			*np = n->next;
			n->dead = 1;
			write_unlock(&n->lock);
710
			neigh_cleanup_and_release(n);
Linus Torvalds's avatar
Linus Torvalds committed
711
712
713
714
715
716
717
718
			continue;
		}
		write_unlock(&n->lock);

next_elt:
		np = &n->next;
	}

719
720
721
	/* Cycle through all hash buckets every base_reachable_time/2 ticks.
	 * ARP entry timeouts range from 1/2 base_reachable_time to 3/2
	 * base_reachable_time.
Linus Torvalds's avatar
Linus Torvalds committed
722
723
724
725
726
727
	 */
	expire = tbl->parms.base_reachable_time >> 1;
	expire /= (tbl->hash_mask + 1);
	if (!expire)
		expire = 1;

728
729
730
731
	if (expire>HZ)
		mod_timer(&tbl->gc_timer, round_jiffies(now + expire));
	else
		mod_timer(&tbl->gc_timer, now + expire);
Linus Torvalds's avatar
Linus Torvalds committed
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766

	write_unlock(&tbl->lock);
}

static __inline__ int neigh_max_probes(struct neighbour *n)
{
	struct neigh_parms *p = n->parms;
	return (n->nud_state & NUD_PROBE ?
		p->ucast_probes :
		p->ucast_probes + p->app_probes + p->mcast_probes);
}

/* Called when a timer expires for a neighbour entry. */

static void neigh_timer_handler(unsigned long arg)
{
	unsigned long now, next;
	struct neighbour *neigh = (struct neighbour *)arg;
	unsigned state;
	int notify = 0;

	write_lock(&neigh->lock);

	state = neigh->nud_state;
	now = jiffies;
	next = now + HZ;

	if (!(state & NUD_IN_TIMER)) {
#ifndef CONFIG_SMP
		printk(KERN_WARNING "neigh: timer & !nud_in_timer\n");
#endif
		goto out;
	}

	if (state & NUD_REACHABLE) {
767
		if (time_before_eq(now,
Linus Torvalds's avatar
Linus Torvalds committed
768
769
770
771
772
773
774
				   neigh->confirmed + neigh->parms->reachable_time)) {
			NEIGH_PRINTK2("neigh %p is still alive.\n", neigh);
			next = neigh->confirmed + neigh->parms->reachable_time;
		} else if (time_before_eq(now,
					  neigh->used + neigh->parms->delay_probe_time)) {
			NEIGH_PRINTK2("neigh %p is delayed.\n", neigh);
			neigh->nud_state = NUD_DELAY;
775
			neigh->updated = jiffies;
Linus Torvalds's avatar
Linus Torvalds committed
776
777
778
779
780
			neigh_suspect(neigh);
			next = now + neigh->parms->delay_probe_time;
		} else {
			NEIGH_PRINTK2("neigh %p is suspected.\n", neigh);
			neigh->nud_state = NUD_STALE;
781
			neigh->updated = jiffies;
Linus Torvalds's avatar
Linus Torvalds committed
782
			neigh_suspect(neigh);
783
			notify = 1;
Linus Torvalds's avatar
Linus Torvalds committed
784
785
		}
	} else if (state & NUD_DELAY) {
786
		if (time_before_eq(now,
Linus Torvalds's avatar
Linus Torvalds committed
787
788
789
				   neigh->confirmed + neigh->parms->delay_probe_time)) {
			NEIGH_PRINTK2("neigh %p is now reachable.\n", neigh);
			neigh->nud_state = NUD_REACHABLE;
790
			neigh->updated = jiffies;
Linus Torvalds's avatar
Linus Torvalds committed
791
			neigh_connect(neigh);
792
			notify = 1;
Linus Torvalds's avatar
Linus Torvalds committed
793
794
795
796
			next = neigh->confirmed + neigh->parms->reachable_time;
		} else {
			NEIGH_PRINTK2("neigh %p is probed.\n", neigh);
			neigh->nud_state = NUD_PROBE;
797
			neigh->updated = jiffies;
Linus Torvalds's avatar
Linus Torvalds committed
798
799
800
801
802
803
804
805
806
807
808
809
810
			atomic_set(&neigh->probes, 0);
			next = now + neigh->parms->retrans_time;
		}
	} else {
		/* NUD_PROBE|NUD_INCOMPLETE */
		next = now + neigh->parms->retrans_time;
	}

	if ((neigh->nud_state & (NUD_INCOMPLETE | NUD_PROBE)) &&
	    atomic_read(&neigh->probes) >= neigh_max_probes(neigh)) {
		struct sk_buff *skb;

		neigh->nud_state = NUD_FAILED;
811
		neigh->updated = jiffies;
Linus Torvalds's avatar
Linus Torvalds committed
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
		notify = 1;
		NEIGH_CACHE_STAT_INC(neigh->tbl, res_failed);
		NEIGH_PRINTK2("neigh %p is failed.\n", neigh);

		/* It is very thin place. report_unreachable is very complicated
		   routine. Particularly, it can hit the same neighbour entry!

		   So that, we try to be accurate and avoid dead loop. --ANK
		 */
		while (neigh->nud_state == NUD_FAILED &&
		       (skb = __skb_dequeue(&neigh->arp_queue)) != NULL) {
			write_unlock(&neigh->lock);
			neigh->ops->error_report(neigh, skb);
			write_lock(&neigh->lock);
		}
		skb_queue_purge(&neigh->arp_queue);
	}

	if (neigh->nud_state & NUD_IN_TIMER) {
		if (time_before(next, jiffies + HZ/2))
			next = jiffies + HZ/2;
833
834
		if (!mod_timer(&neigh->timer, next))
			neigh_hold(neigh);
Linus Torvalds's avatar
Linus Torvalds committed
835
836
837
	}
	if (neigh->nud_state & (NUD_INCOMPLETE | NUD_PROBE)) {
		struct sk_buff *skb = skb_peek(&neigh->arp_queue);
838
839
840
841
		/* keep skb alive even if arp_queue overflows */
		if (skb)
			skb_get(skb);
		write_unlock(&neigh->lock);
Linus Torvalds's avatar
Linus Torvalds committed
842
843
		neigh->ops->solicit(neigh, skb);
		atomic_inc(&neigh->probes);
844
845
846
		if (skb)
			kfree_skb(skb);
	} else {
847
out:
848
849
		write_unlock(&neigh->lock);
	}
Thomas Graf's avatar
Thomas Graf committed
850

851
	if (notify)
Thomas Graf's avatar
Thomas Graf committed
852
		neigh_update_notify(neigh);
Linus Torvalds's avatar
Linus Torvalds committed
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868

	neigh_release(neigh);
}

int __neigh_event_send(struct neighbour *neigh, struct sk_buff *skb)
{
	int rc;
	unsigned long now;

	write_lock_bh(&neigh->lock);

	rc = 0;
	if (neigh->nud_state & (NUD_CONNECTED | NUD_DELAY | NUD_PROBE))
		goto out_unlock_bh;

	now = jiffies;
869

Linus Torvalds's avatar
Linus Torvalds committed
870
871
872
873
	if (!(neigh->nud_state & (NUD_STALE | NUD_INCOMPLETE))) {
		if (neigh->parms->mcast_probes + neigh->parms->app_probes) {
			atomic_set(&neigh->probes, neigh->parms->ucast_probes);
			neigh->nud_state     = NUD_INCOMPLETE;
874
			neigh->updated = jiffies;
875
			neigh_add_timer(neigh, now + 1);
Linus Torvalds's avatar
Linus Torvalds committed
876
877
		} else {
			neigh->nud_state = NUD_FAILED;
878
			neigh->updated = jiffies;
Linus Torvalds's avatar
Linus Torvalds committed
879
880
881
882
883
884
885
886
887
			write_unlock_bh(&neigh->lock);

			if (skb)
				kfree_skb(skb);
			return 1;
		}
	} else if (neigh->nud_state & NUD_STALE) {
		NEIGH_PRINTK2("neigh %p is delayed.\n", neigh);
		neigh->nud_state = NUD_DELAY;
888
		neigh->updated = jiffies;
889
890
		neigh_add_timer(neigh,
				jiffies + neigh->parms->delay_probe_time);
Linus Torvalds's avatar
Linus Torvalds committed
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
	}

	if (neigh->nud_state == NUD_INCOMPLETE) {
		if (skb) {
			if (skb_queue_len(&neigh->arp_queue) >=
			    neigh->parms->queue_len) {
				struct sk_buff *buff;
				buff = neigh->arp_queue.next;
				__skb_unlink(buff, &neigh->arp_queue);
				kfree_skb(buff);
			}
			__skb_queue_tail(&neigh->arp_queue, skb);
		}
		rc = 1;
	}
out_unlock_bh:
	write_unlock_bh(&neigh->lock);
	return rc;
}

911
static void neigh_update_hhs(struct neighbour *neigh)
Linus Torvalds's avatar
Linus Torvalds committed
912
913
{
	struct hh_cache *hh;
914
915
	void (*update)(struct hh_cache*, const struct net_device*, const unsigned char *)
		= neigh->dev->header_ops->cache_update;
Linus Torvalds's avatar
Linus Torvalds committed
916
917
918

	if (update) {
		for (hh = neigh->hh; hh; hh = hh->hh_next) {
919
			write_seqlock_bh(&hh->hh_lock);
Linus Torvalds's avatar
Linus Torvalds committed
920
			update(hh, neigh->dev, neigh->ha);
921
			write_sequnlock_bh(&hh->hh_lock);
Linus Torvalds's avatar
Linus Torvalds committed
922
923
924
925
926
927
928
929
930
931
932
933
934
		}
	}
}



/* Generic update routine.
   -- lladdr is new lladdr or NULL, if it is not supplied.
   -- new    is new state.
   -- flags
	NEIGH_UPDATE_F_OVERRIDE allows to override existing lladdr,
				if it is different.
	NEIGH_UPDATE_F_WEAK_OVERRIDE will suspect existing "connected"
935
				lladdr instead of overriding it
Linus Torvalds's avatar
Linus Torvalds committed
936
937
938
939
940
				if it is different.
				It also allows to retain current state
				if lladdr is unchanged.
	NEIGH_UPDATE_F_ADMIN	means that the change is administrative.

941
	NEIGH_UPDATE_F_OVERRIDE_ISROUTER allows to override existing
Linus Torvalds's avatar
Linus Torvalds committed
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
				NTF_ROUTER flag.
	NEIGH_UPDATE_F_ISROUTER	indicates if the neighbour is known as
				a router.

   Caller MUST hold reference count on the entry.
 */

int neigh_update(struct neighbour *neigh, const u8 *lladdr, u8 new,
		 u32 flags)
{
	u8 old;
	int err;
	int notify = 0;
	struct net_device *dev;
	int update_isrouter = 0;

	write_lock_bh(&neigh->lock);

	dev    = neigh->dev;
	old    = neigh->nud_state;
	err    = -EPERM;

964
	if (!(flags & NEIGH_UPDATE_F_ADMIN) &&
Linus Torvalds's avatar
Linus Torvalds committed
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
	    (old & (NUD_NOARP | NUD_PERMANENT)))
		goto out;

	if (!(new & NUD_VALID)) {
		neigh_del_timer(neigh);
		if (old & NUD_CONNECTED)
			neigh_suspect(neigh);
		neigh->nud_state = new;
		err = 0;
		notify = old & NUD_VALID;
		goto out;
	}

	/* Compare new lladdr with cached one */
	if (!dev->addr_len) {
		/* First case: device needs no address. */
		lladdr = neigh->ha;
	} else if (lladdr) {
		/* The second case: if something is already cached
		   and a new address is proposed:
		   - compare new & old
		   - if they are different, check override flag
		 */
988
		if ((old & NUD_VALID) &&
Linus Torvalds's avatar
Linus Torvalds committed
989
990
991
992
993
994
995
996
997
998
999
1000
		    !memcmp(lladdr, neigh->ha, dev->addr_len))
			lladdr = neigh->ha;
	} else {
		/* No address is supplied; if we know something,
		   use it, otherwise discard the request.
		 */
		err = -EINVAL;
		if (!(old & NUD_VALID))
			goto out;
		lladdr = neigh->ha;
	}

For faster browsing, not all history is shown. View entire blame