summaryrefslogtreecommitdiff
path: root/net/ipv6/ip6_fib.c
blob: ce226c14bef5b1965fb2d254e78f29253d08d8bd (plain)
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
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
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
107
108
109
110
111
112
113
114
115
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
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
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
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
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
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
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
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
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
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
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
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
/*
 *	Linux INET6 implementation 
 *	Forwarding Information Database
 *
 *	Authors:
 *	Pedro Roque		<roque@di.fc.ul.pt>	
 *
 *	$Id: ip6_fib.c,v 1.25 2001/10/31 21:55:55 davem Exp $
 *
 *	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.
 */

/*
 * 	Changes:
 * 	Yuji SEKIYA @USAGI:	Support default route on router node;
 * 				remove ip6_null_entry from the top of
 * 				routing table.
 */
#include <linux/errno.h>
#include <linux/types.h>
#include <linux/net.h>
#include <linux/route.h>
#include <linux/netdevice.h>
#include <linux/in6.h>
#include <linux/init.h>
#include <linux/list.h>

#ifdef 	CONFIG_PROC_FS
#include <linux/proc_fs.h>
#endif

#include <net/ipv6.h>
#include <net/ndisc.h>
#include <net/addrconf.h>

#include <net/ip6_fib.h>
#include <net/ip6_route.h>

#define RT6_DEBUG 2

#if RT6_DEBUG >= 3
#define RT6_TRACE(x...) printk(KERN_DEBUG x)
#else
#define RT6_TRACE(x...) do { ; } while (0)
#endif

struct rt6_statistics	rt6_stats;

static kmem_cache_t * fib6_node_kmem __read_mostly;

enum fib_walk_state_t
{
#ifdef CONFIG_IPV6_SUBTREES
	FWS_S,
#endif
	FWS_L,
	FWS_R,
	FWS_C,
	FWS_U
};

struct fib6_cleaner_t
{
	struct fib6_walker_t w;
	int (*func)(struct rt6_info *, void *arg);
	void *arg;
};

DEFINE_RWLOCK(fib6_walker_lock);


#ifdef CONFIG_IPV6_SUBTREES
#define FWS_INIT FWS_S
#define SUBTREE(fn) ((fn)->subtree)
#else
#define FWS_INIT FWS_L
#define SUBTREE(fn) NULL
#endif

static void fib6_prune_clones(struct fib6_node *fn, struct rt6_info *rt);
static struct fib6_node * fib6_repair_tree(struct fib6_node *fn);

/*
 *	A routing update causes an increase of the serial number on the
 *	affected subtree. This allows for cached routes to be asynchronously
 *	tested when modifications are made to the destination cache as a
 *	result of redirects, path MTU changes, etc.
 */

static __u32 rt_sernum;

static DEFINE_TIMER(ip6_fib_timer, fib6_run_gc, 0, 0);

struct fib6_walker_t fib6_walker_list = {
	.prev	= &fib6_walker_list,
	.next	= &fib6_walker_list, 
};

#define FOR_WALKERS(w) for ((w)=fib6_walker_list.next; (w) != &fib6_walker_list; (w)=(w)->next)

static __inline__ u32 fib6_new_sernum(void)
{
	u32 n = ++rt_sernum;
	if ((__s32)n <= 0)
		rt_sernum = n = 1;
	return n;
}

/*
 *	Auxiliary address test functions for the radix tree.
 *
 *	These assume a 32bit processor (although it will work on 
 *	64bit processors)
 */

/*
 *	test bit
 */

static __inline__ int addr_bit_set(void *token, int fn_bit)
{
	__u32 *addr = token;

	return htonl(1 << ((~fn_bit)&0x1F)) & addr[fn_bit>>5];
}

static __inline__ struct fib6_node * node_alloc(void)
{
	struct fib6_node *fn;

	if ((fn = kmem_cache_alloc(fib6_node_kmem, SLAB_ATOMIC)) != NULL)
		memset(fn, 0, sizeof(struct fib6_node));

	return fn;
}

static __inline__ void node_free(struct fib6_node * fn)
{
	kmem_cache_free(fib6_node_kmem, fn);
}

static __inline__ void rt6_release(struct rt6_info *rt)
{
	if (atomic_dec_and_test(&rt->rt6i_ref))
		dst_free(&rt->u.dst);
}

static struct fib6_table fib6_main_tbl = {
	.tb6_id		= RT6_TABLE_MAIN,
	.tb6_lock	= RW_LOCK_UNLOCKED,
	.tb6_root	= {
		.leaf		= &ip6_null_entry,
		.fn_flags	= RTN_ROOT | RTN_TL_ROOT | RTN_RTINFO,
	},
};

#ifdef CONFIG_IPV6_MULTIPLE_TABLES

static struct fib6_table fib6_local_tbl = {
	.tb6_id		= RT6_TABLE_LOCAL,
	.tb6_lock	= RW_LOCK_UNLOCKED,
	.tb6_root 	= {
		.leaf		= &ip6_null_entry,
		.fn_flags	= RTN_ROOT | RTN_TL_ROOT | RTN_RTINFO,
	},
};

#define FIB_TABLE_HASHSZ 256
static struct hlist_head fib_table_hash[FIB_TABLE_HASHSZ];

static struct fib6_table *fib6_alloc_table(u32 id)
{
	struct fib6_table *table;

	table = kzalloc(sizeof(*table), GFP_ATOMIC);
	if (table != NULL) {
		table->tb6_id = id;
		table->tb6_lock = RW_LOCK_UNLOCKED;
		table->tb6_root.leaf = &ip6_null_entry;
		table->tb6_root.fn_flags = RTN_ROOT | RTN_TL_ROOT | RTN_RTINFO;
	}

	return table;
}

static void fib6_link_table(struct fib6_table *tb)
{
	unsigned int h;

	h = tb->tb6_id & (FIB_TABLE_HASHSZ - 1);

	/*
	 * No protection necessary, this is the only list mutatation
	 * operation, tables never disappear once they exist.
	 */
	hlist_add_head_rcu(&tb->tb6_hlist, &fib_table_hash[h]);
}

struct fib6_table *fib6_new_table(u32 id)
{
	struct fib6_table *tb;

	if (id == 0)
		id = RT6_TABLE_MAIN;
	tb = fib6_get_table(id);
	if (tb)
		return tb;

	tb = fib6_alloc_table(id);
	if (tb != NULL)
		fib6_link_table(tb);

	return tb;
}

struct fib6_table *fib6_get_table(u32 id)
{
	struct fib6_table *tb;
	struct hlist_node *node;
	unsigned int h;

	if (id == 0)
		id = RT6_TABLE_MAIN;
	h = id & (FIB_TABLE_HASHSZ - 1);
	rcu_read_lock();
	hlist_for_each_entry_rcu(tb, node, &fib_table_hash[h], tb6_hlist) {
		if (tb->tb6_id == id) {
			rcu_read_unlock();
			return tb;
		}
	}
	rcu_read_unlock();

	return NULL;
}

static void __init fib6_tables_init(void)
{
	fib6_link_table(&fib6_main_tbl);
	fib6_link_table(&fib6_local_tbl);
}

#else

struct fib6_table *fib6_new_table(u32 id)
{
	return fib6_get_table(id);
}

struct fib6_table *fib6_get_table(u32 id)
{
	return &fib6_main_tbl;
}

struct dst_entry *fib6_rule_lookup(struct flowi *fl, int flags,
				   pol_lookup_t lookup)
{
	return (struct dst_entry *) lookup(&fib6_main_tbl, fl, flags);
}

static void __init fib6_tables_init(void)
{
}

#endif


/*
 *	Routing Table
 *
 *	return the appropriate node for a routing tree "add" operation
 *	by either creating and inserting or by returning an existing
 *	node.
 */

static struct fib6_node * fib6_add_1(struct fib6_node *root, void *addr,
				     int addrlen, int plen,
				     int offset)
{
	struct fib6_node *fn, *in, *ln;
	struct fib6_node *pn = NULL;
	struct rt6key *key;
	int	bit;
       	int	dir = 0;
	__u32	sernum = fib6_new_sernum();

	RT6_TRACE("fib6_add_1\n");

	/* insert node in tree */

	fn = root;

	do {
		key = (struct rt6key *)((u8 *)fn->leaf + offset);

		/*
		 *	Prefix match
		 */
		if (plen < fn->fn_bit ||
		    !ipv6_prefix_equal(&key->addr, addr, fn->fn_bit))
			goto insert_above;
		
		/*
		 *	Exact match ?
		 */
			 
		if (plen == fn->fn_bit) {
			/* clean up an intermediate node */
			if ((fn->fn_flags & RTN_RTINFO) == 0) {
				rt6_release(fn->leaf);
				fn->leaf = NULL;
			}
			
			fn->fn_sernum = sernum;
				
			return fn;
		}

		/*
		 *	We have more bits to go
		 */
			 
		/* Try to walk down on tree. */
		fn->fn_sernum = sernum;
		dir = addr_bit_set(addr, fn->fn_bit);
		pn = fn;
		fn = dir ? fn->right: fn->left;
	} while (fn);

	/*
	 *	We walked to the bottom of tree.
	 *	Create new leaf node without children.
	 */

	ln = node_alloc();

	if (ln == NULL)
		return NULL;
	ln->fn_bit = plen;
			
	ln->parent = pn;
	ln->fn_sernum = sernum;

	if (dir)
		pn->right = ln;
	else
		pn->left  = ln;

	return ln;


insert_above:
	/*
	 * split since we don't have a common prefix anymore or 
	 * we have a less significant route.
	 * we've to insert an intermediate node on the list
	 * this new node will point to the one we need to create
	 * and the current
	 */

	pn = fn->parent;

	/* find 1st bit in difference between the 2 addrs.

	   See comment in __ipv6_addr_diff: bit may be an invalid value,
	   but if it is >= plen, the value is ignored in any case.
	 */
	
	bit = __ipv6_addr_diff(addr, &key->addr, addrlen);

	/* 
	 *		(intermediate)[in]	
	 *	          /	   \
	 *	(new leaf node)[ln] (old node)[fn]
	 */
	if (plen > bit) {
		in = node_alloc();
		ln = node_alloc();
		
		if (in == NULL || ln == NULL) {
			if (in)
				node_free(in);
			if (ln)
				node_free(ln);
			return NULL;
		}

		/* 
		 * new intermediate node. 
		 * RTN_RTINFO will
		 * be off since that an address that chooses one of
		 * the branches would not match less specific routes
		 * in the other branch
		 */

		in->fn_bit = bit;

		in->parent = pn;
		in->leaf = fn->leaf;
		atomic_inc(&in->leaf->rt6i_ref);

		in->fn_sernum = sernum;

		/* update parent pointer */
		if (dir)
			pn->right = in;
		else
			pn->left  = in;

		ln->fn_bit = plen;

		ln->parent = in;
		fn->parent = in;

		ln->fn_sernum = sernum;

		if (addr_bit_set(addr, bit)) {
			in->right = ln;
			in->left  = fn;
		} else {
			in->left  = ln;
			in->right = fn;
		}
	} else { /* plen <= bit */

		/* 
		 *		(new leaf node)[ln]
		 *	          /	   \
		 *	     (old node)[fn] NULL
		 */

		ln = node_alloc();

		if (ln == NULL)
			return NULL;

		ln->fn_bit = plen;

		ln->parent = pn;

		ln->fn_sernum = sernum;
		
		if (dir)
			pn->right = ln;
		else
			pn->left  = ln;

		if (addr_bit_set(&key->addr, plen))
			ln->right = fn;
		else
			ln->left  = fn;

		fn->parent = ln;
	}
	return ln;
}

/*
 *	Insert routing information in a node.
 */

static int fib6_add_rt2node(struct fib6_node *fn, struct rt6_info *rt,
		struct nlmsghdr *nlh,  struct netlink_skb_parms *req)
{
	struct rt6_info *iter = NULL;
	struct rt6_info **ins;

	ins = &fn->leaf;

	if (fn->fn_flags&RTN_TL_ROOT &&
	    fn->leaf == &ip6_null_entry &&
	    !(rt->rt6i_flags & (RTF_DEFAULT | RTF_ADDRCONF)) ){
		fn->leaf = rt;
		rt->u.next = NULL;
		goto out;
	}

	for (iter = fn->leaf; iter; iter=iter->u.next) {
		/*
		 *	Search for duplicates
		 */

		if (iter->rt6i_metric == rt->rt6i_metric) {
			/*
			 *	Same priority level
			 */

			if (iter->rt6i_dev == rt->rt6i_dev &&
			    iter->rt6i_idev == rt->rt6i_idev &&
			    ipv6_addr_equal(&iter->rt6i_gateway,
					    &rt->rt6i_gateway)) {
				if (!(iter->rt6i_flags&RTF_EXPIRES))
					return -EEXIST;
				iter->rt6i_expires = rt->rt6i_expires;
				if (!(rt->rt6i_flags&RTF_EXPIRES)) {
					iter->rt6i_flags &= ~RTF_EXPIRES;
					iter->rt6i_expires = 0;
				}
				return -EEXIST;
			}
		}

		if (iter->rt6i_metric > rt->rt6i_metric)
			break;

		ins = &iter->u.next;
	}

	/*
	 *	insert node
	 */

out:
	rt->u.next = iter;
	*ins = rt;
	rt->rt6i_node = fn;
	atomic_inc(&rt->rt6i_ref);
	inet6_rt_notify(RTM_NEWROUTE, rt, nlh, req);
	rt6_stats.fib_rt_entries++;

	if ((fn->fn_flags & RTN_RTINFO) == 0) {
		rt6_stats.fib_route_nodes++;
		fn->fn_flags |= RTN_RTINFO;
	}

	return 0;
}

static __inline__ void fib6_start_gc(struct rt6_info *rt)
{
	if (ip6_fib_timer.expires == 0 &&
	    (rt->rt6i_flags & (RTF_EXPIRES|RTF_CACHE)))
		mod_timer(&ip6_fib_timer, jiffies + ip6_rt_gc_interval);
}

void fib6_force_start_gc(void)
{
	if (ip6_fib_timer.expires == 0)
		mod_timer(&ip6_fib_timer, jiffies + ip6_rt_gc_interval);
}

/*
 *	Add routing information to the routing tree.
 *	<destination addr>/<source addr>
 *	with source addr info in sub-trees
 */

int fib6_add(struct fib6_node *root, struct rt6_info *rt, 
		struct nlmsghdr *nlh, void *_rtattr, struct netlink_skb_parms *req)
{
	struct fib6_node *fn;
	int err = -ENOMEM;

	fn = fib6_add_1(root, &rt->rt6i_dst.addr, sizeof(struct in6_addr),
			rt->rt6i_dst.plen, offsetof(struct rt6_info, rt6i_dst));

	if (fn == NULL)
		goto out;

#ifdef CONFIG_IPV6_SUBTREES
	if (rt->rt6i_src.plen) {
		struct fib6_node *sn;

		if (fn->subtree == NULL) {
			struct fib6_node *sfn;

			/*
			 * Create subtree.
			 *
			 *		fn[main tree]
			 *		|
			 *		sfn[subtree root]
			 *		   \
			 *		    sn[new leaf node]
			 */

			/* Create subtree root node */
			sfn = node_alloc();
			if (sfn == NULL)
				goto st_failure;

			sfn->leaf = &ip6_null_entry;
			atomic_inc(&ip6_null_entry.rt6i_ref);
			sfn->fn_flags = RTN_ROOT;
			sfn->fn_sernum = fib6_new_sernum();

			/* Now add the first leaf node to new subtree */

			sn = fib6_add_1(sfn, &rt->rt6i_src.addr,
					sizeof(struct in6_addr), rt->rt6i_src.plen,
					offsetof(struct rt6_info, rt6i_src));

			if (sn == NULL) {
				/* If it is failed, discard just allocated
				   root, and then (in st_failure) stale node
				   in main tree.
				 */
				node_free(sfn);
				goto st_failure;
			}

			/* Now link new subtree to main tree */
			sfn->parent = fn;
			fn->subtree = sfn;
			if (fn->leaf == NULL) {
				fn->leaf = rt;
				atomic_inc(&rt->rt6i_ref);
			}
		} else {
			sn = fib6_add_1(fn->subtree, &rt->rt6i_src.addr,
					sizeof(struct in6_addr), rt->rt6i_src.plen,
					offsetof(struct rt6_info, rt6i_src));

			if (sn == NULL)
				goto st_failure;
		}

		fn = sn;
	}
#endif

	err = fib6_add_rt2node(fn, rt, nlh, req);

	if (err == 0) {
		fib6_start_gc(rt);
		if (!(rt->rt6i_flags&RTF_CACHE))
			fib6_prune_clones(fn, rt);
	}

out:
	if (err)
		dst_free(&rt->u.dst);
	return err;

#ifdef CONFIG_IPV6_SUBTREES
	/* Subtree creation failed, probably main tree node
	   is orphan. If it is, shoot it.
	 */
st_failure:
	if (fn && !(fn->fn_flags & (RTN_RTINFO|RTN_ROOT)))
		fib6_repair_tree(fn);
	dst_free(&rt->u.dst);
	return err;
#endif
}

/*
 *	Routing tree lookup
 *
 */

struct lookup_args {
	int		offset;		/* key offset on rt6_info	*/
	struct in6_addr	*addr;		/* search key			*/
};

static struct fib6_node * fib6_lookup_1(struct fib6_node *root,
					struct lookup_args *args)
{
	struct fib6_node *fn;
	int dir;

	/*
	 *	Descend on a tree
	 */

	fn = root;

	for (;;) {
		struct fib6_node *next;

		dir = addr_bit_set(args->addr, fn->fn_bit);

		next = dir ? fn->right : fn->left;

		if (next) {
			fn = next;
			continue;
		}

		break;
	}

	while ((fn->fn_flags & RTN_ROOT) == 0) {
#ifdef CONFIG_IPV6_SUBTREES
		if (fn->subtree) {
			struct fib6_node *st;
			struct lookup_args *narg;

			narg = args + 1;

			if (narg->addr) {
				st = fib6_lookup_1(fn->subtree, narg);

				if (st && !(st->fn_flags & RTN_ROOT))
					return st;
			}
		}
#endif

		if (fn->fn_flags & RTN_RTINFO) {
			struct rt6key *key;

			key = (struct rt6key *) ((u8 *) fn->leaf +
						 args->offset);

			if (ipv6_prefix_equal(&key->addr, args->addr, key->plen))
				return fn;
		}

		fn = fn->parent;
	}

	return NULL;
}

struct fib6_node * fib6_lookup(struct fib6_node *root, struct in6_addr *daddr,
			       struct in6_addr *saddr)
{
	struct lookup_args args[2];
	struct fib6_node *fn;

	args[0].offset = offsetof(struct rt6_info, rt6i_dst);
	args[0].addr = daddr;

#ifdef CONFIG_IPV6_SUBTREES
	args[1].offset = offsetof(struct rt6_info, rt6i_src);
	args[1].addr = saddr;
#endif

	fn = fib6_lookup_1(root, args);

	if (fn == NULL || fn->fn_flags & RTN_TL_ROOT)
		fn = root;

	return fn;
}

/*
 *	Get node with specified destination prefix (and source prefix,
 *	if subtrees are used)
 */


static struct fib6_node * fib6_locate_1(struct fib6_node *root,
					struct in6_addr *addr,
					int plen, int offset)
{
	struct fib6_node *fn;

	for (fn = root; fn ; ) {
		struct rt6key *key = (struct rt6key *)((u8 *)fn->leaf + offset);

		/*
		 *	Prefix match
		 */
		if (plen < fn->fn_bit ||
		    !ipv6_prefix_equal(&key->addr, addr, fn->fn_bit))
			return NULL;

		if (plen == fn->fn_bit)
			return fn;

		/*
		 *	We have more bits to go
		 */
		if (addr_bit_set(addr, fn->fn_bit))
			fn = fn->right;
		else
			fn = fn->left;
	}
	return NULL;
}

struct fib6_node * fib6_locate(struct fib6_node *root,
			       struct in6_addr *daddr, int dst_len,
			       struct in6_addr *saddr, int src_len)
{
	struct fib6_node *fn;

	fn = fib6_locate_1(root, daddr, dst_len,
			   offsetof(struct rt6_info, rt6i_dst));

#ifdef CONFIG_IPV6_SUBTREES
	if (src_len) {
		BUG_TRAP(saddr!=NULL);
		if (fn == NULL)
			fn = fn->subtree;
		if (fn)
			fn = fib6_locate_1(fn, saddr, src_len,
					   offsetof(struct rt6_info, rt6i_src));
	}
#endif

	if (fn && fn->fn_flags&RTN_RTINFO)
		return fn;

	return NULL;
}


/*
 *	Deletion
 *
 */

static struct rt6_info * fib6_find_prefix(struct fib6_node *fn)
{
	if (fn->fn_flags&RTN_ROOT)
		return &ip6_null_entry;

	while(fn) {
		if(fn->left)
			return fn->left->leaf;

		if(fn->right)
			return fn->right->leaf;

		fn = SUBTREE(fn);
	}
	return NULL;
}

/*
 *	Called to trim the tree of intermediate nodes when possible. "fn"
 *	is the node we want to try and remove.
 */

static struct fib6_node * fib6_repair_tree(struct fib6_node *fn)
{
	int children;
	int nstate;
	struct fib6_node *child, *pn;
	struct fib6_walker_t *w;
	int iter = 0;

	for (;;) {
		RT6_TRACE("fixing tree: plen=%d iter=%d\n", fn->fn_bit, iter);
		iter++;

		BUG_TRAP(!(fn->fn_flags&RTN_RTINFO));
		BUG_TRAP(!(fn->fn_flags&RTN_TL_ROOT));
		BUG_TRAP(fn->leaf==NULL);

		children = 0;
		child = NULL;
		if (fn->right) child = fn->right, children |= 1;
		if (fn->left) child = fn->left, children |= 2;

		if (children == 3 || SUBTREE(fn) 
#ifdef CONFIG_IPV6_SUBTREES
		    /* Subtree root (i.e. fn) may have one child */
		    || (children && fn->fn_flags&RTN_ROOT)
#endif
		    ) {
			fn->leaf = fib6_find_prefix(fn);
#if RT6_DEBUG >= 2
			if (fn->leaf==NULL) {
				BUG_TRAP(fn->leaf);
				fn->leaf = &ip6_null_entry;
			}
#endif
			atomic_inc(&fn->leaf->rt6i_ref);
			return fn->parent;
		}

		pn = fn->parent;
#ifdef CONFIG_IPV6_SUBTREES
		if (SUBTREE(pn) == fn) {
			BUG_TRAP(fn->fn_flags&RTN_ROOT);
			SUBTREE(pn) = NULL;
			nstate = FWS_L;
		} else {
			BUG_TRAP(!(fn->fn_flags&RTN_ROOT));
#endif
			if (pn->right == fn) pn->right = child;
			else if (pn->left == fn) pn->left = child;
#if RT6_DEBUG >= 2
			else BUG_TRAP(0);
#endif
			if (child)
				child->parent = pn;
			nstate = FWS_R;
#ifdef CONFIG_IPV6_SUBTREES
		}
#endif

		read_lock(&fib6_walker_lock);
		FOR_WALKERS(w) {
			if (child == NULL) {
				if (w->root == fn) {
					w->root = w->node = NULL;
					RT6_TRACE("W %p adjusted by delroot 1\n", w);
				} else if (w->node == fn) {
					RT6_TRACE("W %p adjusted by delnode 1, s=%d/%d\n", w, w->state, nstate);
					w->node = pn;
					w->state = nstate;
				}
			} else {
				if (w->root == fn) {
					w->root = child;
					RT6_TRACE("W %p adjusted by delroot 2\n", w);
				}
				if (w->node == fn) {
					w->node = child;
					if (children&2) {
						RT6_TRACE("W %p adjusted by delnode 2, s=%d\n", w, w->state);
						w->state = w->state>=FWS_R ? FWS_U : FWS_INIT;
					} else {
						RT6_TRACE("W %p adjusted by delnode 2, s=%d\n", w, w->state);
						w->state = w->state>=FWS_C ? FWS_U : FWS_INIT;
					}
				}
			}
		}
		read_unlock(&fib6_walker_lock);

		node_free(fn);
		if (pn->fn_flags&RTN_RTINFO || SUBTREE(pn))
			return pn;

		rt6_release(pn->leaf);
		pn->leaf = NULL;
		fn = pn;
	}
}

static void fib6_del_route(struct fib6_node *fn, struct rt6_info **rtp,
    struct nlmsghdr *nlh, void *_rtattr, struct netlink_skb_parms *req)
{
	struct fib6_walker_t *w;
	struct rt6_info *rt = *rtp;

	RT6_TRACE("fib6_del_route\n");

	/* Unlink it */
	*rtp = rt->u.next;
	rt->rt6i_node = NULL;
	rt6_stats.fib_rt_entries--;
	rt6_stats.fib_discarded_routes++;

	/* Adjust walkers */
	read_lock(&fib6_walker_lock);
	FOR_WALKERS(w) {
		if (w->state == FWS_C && w->leaf == rt) {
			RT6_TRACE("walker %p adjusted by delroute\n", w);
			w->leaf = rt->u.next;
			if (w->leaf == NULL)
				w->state = FWS_U;
		}
	}
	read_unlock(&fib6_walker_lock);

	rt->u.next = NULL;

	if (fn->leaf == NULL && fn->fn_flags&RTN_TL_ROOT)
		fn->leaf = &ip6_null_entry;

	/* If it was last route, expunge its radix tree node */
	if (fn->leaf == NULL) {
		fn->fn_flags &= ~RTN_RTINFO;
		rt6_stats.fib_route_nodes--;
		fn = fib6_repair_tree(fn);
	}

	if (atomic_read(&rt->rt6i_ref) != 1) {
		/* This route is used as dummy address holder in some split
		 * nodes. It is not leaked, but it still holds other resources,
		 * which must be released in time. So, scan ascendant nodes
		 * and replace dummy references to this route with references
		 * to still alive ones.
		 */
		while (fn) {
			if (!(fn->fn_flags&RTN_RTINFO) && fn->leaf == rt) {
				fn->leaf = fib6_find_prefix(fn);
				atomic_inc(&fn->leaf->rt6i_ref);
				rt6_release(rt);
			}
			fn = fn->parent;
		}
		/* No more references are possible at this point. */
		if (atomic_read(&rt->rt6i_ref) != 1) BUG();
	}

	inet6_rt_notify(RTM_DELROUTE, rt, nlh, req);
	rt6_release(rt);
}

int fib6_del(struct rt6_info *rt, struct nlmsghdr *nlh, void *_rtattr, struct netlink_skb_parms *req)
{
	struct fib6_node *fn = rt->rt6i_node;
	struct rt6_info **rtp;

#if RT6_DEBUG >= 2
	if (rt->u.dst.obsolete>0) {
		BUG_TRAP(fn==NULL);
		return -ENOENT;
	}
#endif
	if (fn == NULL || rt == &ip6_null_entry)
		return -ENOENT;

	BUG_TRAP(fn->fn_flags&RTN_RTINFO);

	if (!(rt->rt6i_flags&RTF_CACHE))
		fib6_prune_clones(fn, rt);

	/*
	 *	Walk the leaf entries looking for ourself
	 */

	for (rtp = &fn->leaf; *rtp; rtp = &(*rtp)->u.next) {
		if (*rtp == rt) {
			fib6_del_route(fn, rtp, nlh, _rtattr, req);
			return 0;
		}
	}
	return -ENOENT;
}

/*
 *	Tree traversal function.
 *
 *	Certainly, it is not interrupt safe.
 *	However, it is internally reenterable wrt itself and fib6_add/fib6_del.
 *	It means, that we can modify tree during walking
 *	and use this function for garbage collection, clone pruning,
 *	cleaning tree when a device goes down etc. etc.	
 *
 *	It guarantees that every node will be traversed,
 *	and that it will be traversed only once.
 *
 *	Callback function w->func may return:
 *	0 -> continue walking.
 *	positive value -> walking is suspended (used by tree dumps,
 *	and probably by gc, if it will be split to several slices)
 *	negative value -> terminate walking.
 *
 *	The function itself returns:
 *	0   -> walk is complete.
 *	>0  -> walk is incomplete (i.e. suspended)
 *	<0  -> walk is terminated by an error.
 */

int fib6_walk_continue(struct fib6_walker_t *w)
{
	struct fib6_node *fn, *pn;

	for (;;) {
		fn = w->node;
		if (fn == NULL)
			return 0;

		if (w->prune && fn != w->root &&
		    fn->fn_flags&RTN_RTINFO && w->state < FWS_C) {
			w->state = FWS_C;
			w->leaf = fn->leaf;
		}
		switch (w->state) {
#ifdef CONFIG_IPV6_SUBTREES
		case FWS_S:
			if (SUBTREE(fn)) {
				w->node = SUBTREE(fn);
				continue;
			}
			w->state = FWS_L;
#endif	
		case FWS_L:
			if (fn->left) {
				w->node = fn->left;
				w->state = FWS_INIT;
				continue;
			}
			w->state = FWS_R;
		case FWS_R:
			if (fn->right) {
				w->node = fn->right;
				w->state = FWS_INIT;
				continue;
			}
			w->state = FWS_C;
			w->leaf = fn->leaf;
		case FWS_C:
			if (w->leaf && fn->fn_flags&RTN_RTINFO) {
				int err = w->func(w);
				if (err)
					return err;
				continue;
			}
			w->state = FWS_U;
		case FWS_U:
			if (fn == w->root)
				return 0;
			pn = fn->parent;
			w->node = pn;
#ifdef CONFIG_IPV6_SUBTREES
			if (SUBTREE(pn) == fn) {
				BUG_TRAP(fn->fn_flags&RTN_ROOT);
				w->state = FWS_L;
				continue;
			}
#endif
			if (pn->left == fn) {
				w->state = FWS_R;
				continue;
			}
			if (pn->right == fn) {
				w->state = FWS_C;
				w->leaf = w->node->leaf;
				continue;
			}
#if RT6_DEBUG >= 2
			BUG_TRAP(0);
#endif
		}
	}
}

int fib6_walk(struct fib6_walker_t *w)
{
	int res;

	w->state = FWS_INIT;
	w->node = w->root;

	fib6_walker_link(w);
	res = fib6_walk_continue(w);
	if (res <= 0)
		fib6_walker_unlink(w);
	return res;
}

static int fib6_clean_node(struct fib6_walker_t *w)
{
	int res;
	struct rt6_info *rt;
	struct fib6_cleaner_t *c = (struct fib6_cleaner_t*)w;

	for (rt = w->leaf; rt; rt = rt->u.next) {
		res = c->func(rt, c->arg);
		if (res < 0) {
			w->leaf = rt;
			res = fib6_del(rt, NULL, NULL, NULL);
			if (res) {
#if RT6_DEBUG >= 2
				printk(KERN_DEBUG "fib6_clean_node: del failed: rt=%p@%p err=%d\n", rt, rt->rt6i_node, res);
#endif
				continue;
			}
			return 0;
		}
		BUG_TRAP(res==0);
	}
	w->leaf = rt;
	return 0;
}

/*
 *	Convenient frontend to tree walker.
 *	
 *	func is called on each route.
 *		It may return -1 -> delete this route.
 *		              0  -> continue walking
 *
 *	prune==1 -> only immediate children of node (certainly,
 *	ignoring pure split nodes) will be scanned.
 */

void fib6_clean_tree(struct fib6_node *root,
		     int (*func)(struct rt6_info *, void *arg),
		     int prune, void *arg)
{
	struct fib6_cleaner_t c;

	c.w.root = root;
	c.w.func = fib6_clean_node;
	c.w.prune = prune;
	c.func = func;
	c.arg = arg;

	fib6_walk(&c.w);
}

void fib6_clean_all(int (*func)(struct rt6_info *, void *arg),
		    int prune, void *arg)
{
	int i;
	struct fib6_table *table;

	for (i = FIB6_TABLE_MIN; i <= FIB6_TABLE_MAX; i++) {
		table = fib6_get_table(i);
		if (table != NULL) {
			write_lock_bh(&table->tb6_lock);
			fib6_clean_tree(&table->tb6_root, func, prune, arg);
			write_unlock_bh(&table->tb6_lock);
		}
	}
}

static int fib6_prune_clone(struct rt6_info *rt, void *arg)
{
	if (rt->rt6i_flags & RTF_CACHE) {
		RT6_TRACE("pruning clone %p\n", rt);
		return -1;
	}

	return 0;
}

static void fib6_prune_clones(struct fib6_node *fn, struct rt6_info *rt)
{
	fib6_clean_tree(fn, fib6_prune_clone, 1, rt);
}

/*
 *	Garbage collection
 */

static struct fib6_gc_args
{
	int			timeout;
	int			more;
} gc_args;

static int fib6_age(struct rt6_info *rt, void *arg)
{
	unsigned long now = jiffies;

	/*
	 *	check addrconf expiration here.
	 *	Routes are expired even if they are in use.
	 *
	 *	Also age clones. Note, that clones are aged out
	 *	only if they are not in use now.
	 */

	if (rt->rt6i_flags&RTF_EXPIRES && rt->rt6i_expires) {
		if (time_after(now, rt->rt6i_expires)) {
			RT6_TRACE("expiring %p\n", rt);
			return -1;
		}
		gc_args.more++;
	} else if (rt->rt6i_flags & RTF_CACHE) {
		if (atomic_read(&rt->u.dst.__refcnt) == 0 &&
		    time_after_eq(now, rt->u.dst.lastuse + gc_args.timeout)) {
			RT6_TRACE("aging clone %p\n", rt);
			return -1;
		} else if ((rt->rt6i_flags & RTF_GATEWAY) &&
			   (!(rt->rt6i_nexthop->flags & NTF_ROUTER))) {
			RT6_TRACE("purging route %p via non-router but gateway\n",
				  rt);
			return -1;
		}
		gc_args.more++;
	}

	return 0;
}

static DEFINE_SPINLOCK(fib6_gc_lock);

void fib6_run_gc(unsigned long dummy)
{
	if (dummy != ~0UL) {
		spin_lock_bh(&fib6_gc_lock);
		gc_args.timeout = dummy ? (int)dummy : ip6_rt_gc_interval;
	} else {
		local_bh_disable();
		if (!spin_trylock(&fib6_gc_lock)) {
			mod_timer(&ip6_fib_timer, jiffies + HZ);
			local_bh_enable();
			return;
		}
		gc_args.timeout = ip6_rt_gc_interval;
	}
	gc_args.more = 0;

	ndisc_dst_gc(&gc_args.more);
	fib6_clean_all(fib6_age, 0, NULL);

	if (gc_args.more)
		mod_timer(&ip6_fib_timer, jiffies + ip6_rt_gc_interval);
	else {
		del_timer(&ip6_fib_timer);
		ip6_fib_timer.expires = 0;
	}
	spin_unlock_bh(&fib6_gc_lock);
}

void __init fib6_init(void)
{
	fib6_node_kmem = kmem_cache_create("fib6_nodes",
					   sizeof(struct fib6_node),
					   0, SLAB_HWCACHE_ALIGN,
					   NULL, NULL);
	if (!fib6_node_kmem)
		panic("cannot create fib6_nodes cache");

	fib6_tables_init();
}

void fib6_gc_cleanup(void)
{
	del_timer(&ip6_fib_timer);
	kmem_cache_destroy(fib6_node_kmem);
}