summaryrefslogtreecommitdiff
path: root/net/mac80211/mesh_pathtbl.c
blob: edf167e3b8f391d65784bc56f3a3f43fc07b9169 (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
/*
 * Copyright (c) 2008, 2009 open80211s Ltd.
 * Author:     Luis Carlos Cobo <luisca@cozybit.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <linux/etherdevice.h>
#include <linux/list.h>
#include <linux/random.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/string.h>
#include <net/mac80211.h>
#include "wme.h"
#include "ieee80211_i.h"
#include "mesh.h"

#ifdef CONFIG_MAC80211_VERBOSE_MPATH_DEBUG
#define mpath_dbg(fmt, args...)	printk(KERN_DEBUG fmt, ##args)
#else
#define mpath_dbg(fmt, args...)	do { (void)(0); } while (0)
#endif

/* There will be initially 2^INIT_PATHS_SIZE_ORDER buckets */
#define INIT_PATHS_SIZE_ORDER	2

/* Keep the mean chain length below this constant */
#define MEAN_CHAIN_LEN		2

#define MPATH_EXPIRED(mpath) ((mpath->flags & MESH_PATH_ACTIVE) && \
				time_after(jiffies, mpath->exp_time) && \
				!(mpath->flags & MESH_PATH_FIXED))

struct mpath_node {
	struct hlist_node list;
	struct rcu_head rcu;
	/* This indirection allows two different tables to point to the same
	 * mesh_path structure, useful when resizing
	 */
	struct mesh_path *mpath;
};

static struct mesh_table __rcu *mesh_paths;
static struct mesh_table __rcu *mpp_paths; /* Store paths for MPP&MAP */

int mesh_paths_generation;

/* This lock will have the grow table function as writer and add / delete nodes
 * as readers. RCU provides sufficient protection only when reading the table
 * (i.e. doing lookups).  Adding or adding or removing nodes requires we take
 * the read lock or we risk operating on an old table.  The write lock is only
 * needed when modifying the number of buckets a table.
 */
static DEFINE_RWLOCK(pathtbl_resize_lock);


static inline struct mesh_table *resize_dereference_mesh_paths(void)
{
	return rcu_dereference_protected(mesh_paths,
		lockdep_is_held(&pathtbl_resize_lock));
}

static inline struct mesh_table *resize_dereference_mpp_paths(void)
{
	return rcu_dereference_protected(mpp_paths,
		lockdep_is_held(&pathtbl_resize_lock));
}

/*
 * CAREFUL -- "tbl" must not be an expression,
 * in particular not an rcu_dereference(), since
 * it's used twice. So it is illegal to do
 *	for_each_mesh_entry(rcu_dereference(...), ...)
 */
#define for_each_mesh_entry(tbl, p, node, i) \
	for (i = 0; i <= tbl->hash_mask; i++) \
		hlist_for_each_entry_rcu(node, p, &tbl->hash_buckets[i], list)


static struct mesh_table *mesh_table_alloc(int size_order)
{
	int i;
	struct mesh_table *newtbl;

	newtbl = kmalloc(sizeof(struct mesh_table), GFP_ATOMIC);
	if (!newtbl)
		return NULL;

	newtbl->hash_buckets = kzalloc(sizeof(struct hlist_head) *
			(1 << size_order), GFP_ATOMIC);

	if (!newtbl->hash_buckets) {
		kfree(newtbl);
		return NULL;
	}

	newtbl->hashwlock = kmalloc(sizeof(spinlock_t) *
			(1 << size_order), GFP_ATOMIC);
	if (!newtbl->hashwlock) {
		kfree(newtbl->hash_buckets);
		kfree(newtbl);
		return NULL;
	}

	newtbl->size_order = size_order;
	newtbl->hash_mask = (1 << size_order) - 1;
	atomic_set(&newtbl->entries,  0);
	get_random_bytes(&newtbl->hash_rnd,
			sizeof(newtbl->hash_rnd));
	for (i = 0; i <= newtbl->hash_mask; i++)
		spin_lock_init(&newtbl->hashwlock[i]);
	spin_lock_init(&newtbl->gates_lock);

	return newtbl;
}

static void __mesh_table_free(struct mesh_table *tbl)
{
	kfree(tbl->hash_buckets);
	kfree(tbl->hashwlock);
	kfree(tbl);
}

static void mesh_table_free(struct mesh_table *tbl, bool free_leafs)
{
	struct hlist_head *mesh_hash;
	struct hlist_node *p, *q;
	struct mpath_node *gate;
	int i;

	mesh_hash = tbl->hash_buckets;
	for (i = 0; i <= tbl->hash_mask; i++) {
		spin_lock_bh(&tbl->hashwlock[i]);
		hlist_for_each_safe(p, q, &mesh_hash[i]) {
			tbl->free_node(p, free_leafs);
			atomic_dec(&tbl->entries);
		}
		spin_unlock_bh(&tbl->hashwlock[i]);
	}
	if (free_leafs) {
		spin_lock_bh(&tbl->gates_lock);
		hlist_for_each_entry_safe(gate, p, q,
					 tbl->known_gates, list) {
			hlist_del(&gate->list);
			kfree(gate);
		}
		kfree(tbl->known_gates);
		spin_unlock_bh(&tbl->gates_lock);
	}

	__mesh_table_free(tbl);
}

static int mesh_table_grow(struct mesh_table *oldtbl,
			   struct mesh_table *newtbl)
{
	struct hlist_head *oldhash;
	struct hlist_node *p, *q;
	int i;

	if (atomic_read(&oldtbl->entries)
			< oldtbl->mean_chain_len * (oldtbl->hash_mask + 1))
		return -EAGAIN;

	newtbl->free_node = oldtbl->free_node;
	newtbl->mean_chain_len = oldtbl->mean_chain_len;
	newtbl->copy_node = oldtbl->copy_node;
	newtbl->known_gates = oldtbl->known_gates;
	atomic_set(&newtbl->entries, atomic_read(&oldtbl->entries));

	oldhash = oldtbl->hash_buckets;
	for (i = 0; i <= oldtbl->hash_mask; i++)
		hlist_for_each(p, &oldhash[i])
			if (oldtbl->copy_node(p, newtbl) < 0)
				goto errcopy;

	return 0;

errcopy:
	for (i = 0; i <= newtbl->hash_mask; i++) {
		hlist_for_each_safe(p, q, &newtbl->hash_buckets[i])
			oldtbl->free_node(p, 0);
	}
	return -ENOMEM;
}

static u32 mesh_table_hash(u8 *addr, struct ieee80211_sub_if_data *sdata,
			   struct mesh_table *tbl)
{
	/* Use last four bytes of hw addr and interface index as hash index */
	return jhash_2words(*(u32 *)(addr+2), sdata->dev->ifindex, tbl->hash_rnd)
		& tbl->hash_mask;
}


/**
 *
 * mesh_path_assign_nexthop - update mesh path next hop
 *
 * @mpath: mesh path to update
 * @sta: next hop to assign
 *
 * Locking: mpath->state_lock must be held when calling this function
 */
void mesh_path_assign_nexthop(struct mesh_path *mpath, struct sta_info *sta)
{
	struct sk_buff *skb;
	struct ieee80211_hdr *hdr;
	struct sk_buff_head tmpq;
	unsigned long flags;

	rcu_assign_pointer(mpath->next_hop, sta);

	__skb_queue_head_init(&tmpq);

	spin_lock_irqsave(&mpath->frame_queue.lock, flags);

	while ((skb = __skb_dequeue(&mpath->frame_queue)) != NULL) {
		hdr = (struct ieee80211_hdr *) skb->data;
		memcpy(hdr->addr1, sta->sta.addr, ETH_ALEN);
		memcpy(hdr->addr2, mpath->sdata->vif.addr, ETH_ALEN);
		__skb_queue_tail(&tmpq, skb);
	}

	skb_queue_splice(&tmpq, &mpath->frame_queue);
	spin_unlock_irqrestore(&mpath->frame_queue.lock, flags);
}

static void prepare_for_gate(struct sk_buff *skb, char *dst_addr,
			     struct mesh_path *gate_mpath)
{
	struct ieee80211_hdr *hdr;
	struct ieee80211s_hdr *mshdr;
	int mesh_hdrlen, hdrlen;
	char *next_hop;

	hdr = (struct ieee80211_hdr *) skb->data;
	hdrlen = ieee80211_hdrlen(hdr->frame_control);
	mshdr = (struct ieee80211s_hdr *) (skb->data + hdrlen);

	if (!(mshdr->flags & MESH_FLAGS_AE)) {
		/* size of the fixed part of the mesh header */
		mesh_hdrlen = 6;

		/* make room for the two extended addresses */
		skb_push(skb, 2 * ETH_ALEN);
		memmove(skb->data, hdr, hdrlen + mesh_hdrlen);

		hdr = (struct ieee80211_hdr *) skb->data;

		/* we preserve the previous mesh header and only add
		 * the new addreses */
		mshdr = (struct ieee80211s_hdr *) (skb->data + hdrlen);
		mshdr->flags = MESH_FLAGS_AE_A5_A6;
		memcpy(mshdr->eaddr1, hdr->addr3, ETH_ALEN);
		memcpy(mshdr->eaddr2, hdr->addr4, ETH_ALEN);
	}

	/* update next hop */
	hdr = (struct ieee80211_hdr *) skb->data;
	rcu_read_lock();
	next_hop = rcu_dereference(gate_mpath->next_hop)->sta.addr;
	memcpy(hdr->addr1, next_hop, ETH_ALEN);
	rcu_read_unlock();
	memcpy(hdr->addr2, gate_mpath->sdata->vif.addr, ETH_ALEN);
	memcpy(hdr->addr3, dst_addr, ETH_ALEN);
}

/**
 *
 * mesh_path_move_to_queue - Move or copy frames from one mpath queue to another
 *
 * This function is used to transfer or copy frames from an unresolved mpath to
 * a gate mpath.  The function also adds the Address Extension field and
 * updates the next hop.
 *
 * If a frame already has an Address Extension field, only the next hop and
 * destination addresses are updated.
 *
 * The gate mpath must be an active mpath with a valid mpath->next_hop.
 *
 * @mpath: An active mpath the frames will be sent to (i.e. the gate)
 * @from_mpath: The failed mpath
 * @copy: When true, copy all the frames to the new mpath queue.  When false,
 * move them.
 */
static void mesh_path_move_to_queue(struct mesh_path *gate_mpath,
				    struct mesh_path *from_mpath,
				    bool copy)
{
	struct sk_buff *skb, *cp_skb = NULL;
	struct sk_buff_head gateq, failq;
	unsigned long flags;
	int num_skbs;

	BUG_ON(gate_mpath == from_mpath);
	BUG_ON(!gate_mpath->next_hop);

	__skb_queue_head_init(&gateq);
	__skb_queue_head_init(&failq);

	spin_lock_irqsave(&from_mpath->frame_queue.lock, flags);
	skb_queue_splice_init(&from_mpath->frame_queue, &failq);
	spin_unlock_irqrestore(&from_mpath->frame_queue.lock, flags);

	num_skbs = skb_queue_len(&failq);

	while (num_skbs--) {
		skb = __skb_dequeue(&failq);
		if (copy) {
			cp_skb = skb_copy(skb, GFP_ATOMIC);
			if (cp_skb)
				__skb_queue_tail(&failq, cp_skb);
		}

		prepare_for_gate(skb, gate_mpath->dst, gate_mpath);
		__skb_queue_tail(&gateq, skb);
	}

	spin_lock_irqsave(&gate_mpath->frame_queue.lock, flags);
	skb_queue_splice(&gateq, &gate_mpath->frame_queue);
	mpath_dbg("Mpath queue for gate %pM has %d frames\n",
			gate_mpath->dst,
			skb_queue_len(&gate_mpath->frame_queue));
	spin_unlock_irqrestore(&gate_mpath->frame_queue.lock, flags);

	if (!copy)
		return;

	spin_lock_irqsave(&from_mpath->frame_queue.lock, flags);
	skb_queue_splice(&failq, &from_mpath->frame_queue);
	spin_unlock_irqrestore(&from_mpath->frame_queue.lock, flags);
}


static struct mesh_path *path_lookup(struct mesh_table *tbl, u8 *dst,
					  struct ieee80211_sub_if_data *sdata)
{
	struct mesh_path *mpath;
	struct hlist_node *n;
	struct hlist_head *bucket;
	struct mpath_node *node;

	bucket = &tbl->hash_buckets[mesh_table_hash(dst, sdata, tbl)];
	hlist_for_each_entry_rcu(node, n, bucket, list) {
		mpath = node->mpath;
		if (mpath->sdata == sdata &&
				memcmp(dst, mpath->dst, ETH_ALEN) == 0) {
			if (MPATH_EXPIRED(mpath)) {
				spin_lock_bh(&mpath->state_lock);
				mpath->flags &= ~MESH_PATH_ACTIVE;
				spin_unlock_bh(&mpath->state_lock);
			}
			return mpath;
		}
	}
	return NULL;
}

/**
 * mesh_path_lookup - look up a path in the mesh path table
 * @dst: hardware address (ETH_ALEN length) of destination
 * @sdata: local subif
 *
 * Returns: pointer to the mesh path structure, or NULL if not found
 *
 * Locking: must be called within a read rcu section.
 */
struct mesh_path *mesh_path_lookup(u8 *dst, struct ieee80211_sub_if_data *sdata)
{
	return path_lookup(rcu_dereference(mesh_paths), dst, sdata);
}

struct mesh_path *mpp_path_lookup(u8 *dst, struct ieee80211_sub_if_data *sdata)
{
	return path_lookup(rcu_dereference(mpp_paths), dst, sdata);
}


/**
 * mesh_path_lookup_by_idx - look up a path in the mesh path table by its index
 * @idx: index
 * @sdata: local subif, or NULL for all entries
 *
 * Returns: pointer to the mesh path structure, or NULL if not found.
 *
 * Locking: must be called within a read rcu section.
 */
struct mesh_path *mesh_path_lookup_by_idx(int idx, struct ieee80211_sub_if_data *sdata)
{
	struct mesh_table *tbl = rcu_dereference(mesh_paths);
	struct mpath_node *node;
	struct hlist_node *p;
	int i;
	int j = 0;

	for_each_mesh_entry(tbl, p, node, i) {
		if (sdata && node->mpath->sdata != sdata)
			continue;
		if (j++ == idx) {
			if (MPATH_EXPIRED(node->mpath)) {
				spin_lock_bh(&node->mpath->state_lock);
				node->mpath->flags &= ~MESH_PATH_ACTIVE;
				spin_unlock_bh(&node->mpath->state_lock);
			}
			return node->mpath;
		}
	}

	return NULL;
}

static void mesh_gate_node_reclaim(struct rcu_head *rp)
{
	struct mpath_node *node = container_of(rp, struct mpath_node, rcu);
	kfree(node);
}

/**
 * mesh_path_add_gate - add the given mpath to a mesh gate to our path table
 * @mpath: gate path to add to table
 */
int mesh_path_add_gate(struct mesh_path *mpath)
{
	struct mesh_table *tbl;
	struct mpath_node *gate, *new_gate;
	struct hlist_node *n;
	int err;

	rcu_read_lock();
	tbl = rcu_dereference(mesh_paths);

	hlist_for_each_entry_rcu(gate, n, tbl->known_gates, list)
		if (gate->mpath == mpath) {
			err = -EEXIST;
			goto err_rcu;
		}

	new_gate = kzalloc(sizeof(struct mpath_node), GFP_ATOMIC);
	if (!new_gate) {
		err = -ENOMEM;
		goto err_rcu;
	}

	mpath->is_gate = true;
	mpath->sdata->u.mesh.num_gates++;
	new_gate->mpath = mpath;
	spin_lock_bh(&tbl->gates_lock);
	hlist_add_head_rcu(&new_gate->list, tbl->known_gates);
	spin_unlock_bh(&tbl->gates_lock);
	rcu_read_unlock();
	mpath_dbg("Mesh path (%s): Recorded new gate: %pM. %d known gates\n",
		  mpath->sdata->name, mpath->dst,
		  mpath->sdata->u.mesh.num_gates);
	return 0;
err_rcu:
	rcu_read_unlock();
	return err;
}

/**
 * mesh_gate_del - remove a mesh gate from the list of known gates
 * @tbl: table which holds our list of known gates
 * @mpath: gate mpath
 *
 * Returns: 0 on success
 *
 * Locking: must be called inside rcu_read_lock() section
 */
static int mesh_gate_del(struct mesh_table *tbl, struct mesh_path *mpath)
{
	struct mpath_node *gate;
	struct hlist_node *p, *q;

	hlist_for_each_entry_safe(gate, p, q, tbl->known_gates, list)
		if (gate->mpath == mpath) {
			spin_lock_bh(&tbl->gates_lock);
			hlist_del_rcu(&gate->list);
			call_rcu(&gate->rcu, mesh_gate_node_reclaim);
			spin_unlock_bh(&tbl->gates_lock);
			mpath->sdata->u.mesh.num_gates--;
			mpath->is_gate = false;
			mpath_dbg("Mesh path (%s): Deleted gate: %pM. "
				  "%d known gates\n", mpath->sdata->name,
				  mpath->dst, mpath->sdata->u.mesh.num_gates);
			break;
		}

	return 0;
}

/**
 * mesh_gate_num - number of gates known to this interface
 * @sdata: subif data
 */
int mesh_gate_num(struct ieee80211_sub_if_data *sdata)
{
	return sdata->u.mesh.num_gates;
}

/**
 * mesh_path_add - allocate and add a new path to the mesh path table
 * @addr: destination address of the path (ETH_ALEN length)
 * @sdata: local subif
 *
 * Returns: 0 on success
 *
 * State: the initial state of the new path is set to 0
 */
int mesh_path_add(u8 *dst, struct ieee80211_sub_if_data *sdata)
{
	struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
	struct ieee80211_local *local = sdata->local;
	struct mesh_table *tbl;
	struct mesh_path *mpath, *new_mpath;
	struct mpath_node *node, *new_node;
	struct hlist_head *bucket;
	struct hlist_node *n;
	int grow = 0;
	int err = 0;
	u32 hash_idx;

	if (memcmp(dst, sdata->vif.addr, ETH_ALEN) == 0)
		/* never add ourselves as neighbours */
		return -ENOTSUPP;

	if (is_multicast_ether_addr(dst))
		return -ENOTSUPP;

	if (atomic_add_unless(&sdata->u.mesh.mpaths, 1, MESH_MAX_MPATHS) == 0)
		return -ENOSPC;

	err = -ENOMEM;
	new_mpath = kzalloc(sizeof(struct mesh_path), GFP_ATOMIC);
	if (!new_mpath)
		goto err_path_alloc;

	new_node = kmalloc(sizeof(struct mpath_node), GFP_ATOMIC);
	if (!new_node)
		goto err_node_alloc;

	read_lock_bh(&pathtbl_resize_lock);
	memcpy(new_mpath->dst, dst, ETH_ALEN);
	new_mpath->sdata = sdata;
	new_mpath->flags = 0;
	skb_queue_head_init(&new_mpath->frame_queue);
	new_node->mpath = new_mpath;
	new_mpath->timer.data = (unsigned long) new_mpath;
	new_mpath->timer.function = mesh_path_timer;
	new_mpath->exp_time = jiffies;
	spin_lock_init(&new_mpath->state_lock);
	init_timer(&new_mpath->timer);

	tbl = resize_dereference_mesh_paths();

	hash_idx = mesh_table_hash(dst, sdata, tbl);
	bucket = &tbl->hash_buckets[hash_idx];

	spin_lock_bh(&tbl->hashwlock[hash_idx]);

	err = -EEXIST;
	hlist_for_each_entry(node, n, bucket, list) {
		mpath = node->mpath;
		if (mpath->sdata == sdata && memcmp(dst, mpath->dst, ETH_ALEN) == 0)
			goto err_exists;
	}

	hlist_add_head_rcu(&new_node->list, bucket);
	if (atomic_inc_return(&tbl->entries) >=
	    tbl->mean_chain_len * (tbl->hash_mask + 1))
		grow = 1;

	mesh_paths_generation++;

	spin_unlock_bh(&tbl->hashwlock[hash_idx]);
	read_unlock_bh(&pathtbl_resize_lock);
	if (grow) {
		set_bit(MESH_WORK_GROW_MPATH_TABLE,  &ifmsh->wrkq_flags);
		ieee80211_queue_work(&local->hw, &sdata->work);
	}
	return 0;

err_exists:
	spin_unlock_bh(&tbl->hashwlock[hash_idx]);
	read_unlock_bh(&pathtbl_resize_lock);
	kfree(new_node);
err_node_alloc:
	kfree(new_mpath);
err_path_alloc:
	atomic_dec(&sdata->u.mesh.mpaths);
	return err;
}

static void mesh_table_free_rcu(struct rcu_head *rcu)
{
	struct mesh_table *tbl = container_of(rcu, struct mesh_table, rcu_head);

	mesh_table_free(tbl, false);
}

void mesh_mpath_table_grow(void)
{
	struct mesh_table *oldtbl, *newtbl;

	write_lock_bh(&pathtbl_resize_lock);
	oldtbl = resize_dereference_mesh_paths();
	newtbl = mesh_table_alloc(oldtbl->size_order + 1);
	if (!newtbl)
		goto out;
	if (mesh_table_grow(oldtbl, newtbl) < 0) {
		__mesh_table_free(newtbl);
		goto out;
	}
	rcu_assign_pointer(mesh_paths, newtbl);

	call_rcu(&oldtbl->rcu_head, mesh_table_free_rcu);

 out:
	write_unlock_bh(&pathtbl_resize_lock);
}

void mesh_mpp_table_grow(void)
{
	struct mesh_table *oldtbl, *newtbl;

	write_lock_bh(&pathtbl_resize_lock);
	oldtbl = resize_dereference_mpp_paths();
	newtbl = mesh_table_alloc(oldtbl->size_order + 1);
	if (!newtbl)
		goto out;
	if (mesh_table_grow(oldtbl, newtbl) < 0) {
		__mesh_table_free(newtbl);
		goto out;
	}
	rcu_assign_pointer(mpp_paths, newtbl);
	call_rcu(&oldtbl->rcu_head, mesh_table_free_rcu);

 out:
	write_unlock_bh(&pathtbl_resize_lock);
}

int mpp_path_add(u8 *dst, u8 *mpp, struct ieee80211_sub_if_data *sdata)
{
	struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
	struct ieee80211_local *local = sdata->local;
	struct mesh_table *tbl;
	struct mesh_path *mpath, *new_mpath;
	struct mpath_node *node, *new_node;
	struct hlist_head *bucket;
	struct hlist_node *n;
	int grow = 0;
	int err = 0;
	u32 hash_idx;

	if (memcmp(dst, sdata->vif.addr, ETH_ALEN) == 0)
		/* never add ourselves as neighbours */
		return -ENOTSUPP;

	if (is_multicast_ether_addr(dst))
		return -ENOTSUPP;

	err = -ENOMEM;
	new_mpath = kzalloc(sizeof(struct mesh_path), GFP_ATOMIC);
	if (!new_mpath)
		goto err_path_alloc;

	new_node = kmalloc(sizeof(struct mpath_node), GFP_ATOMIC);
	if (!new_node)
		goto err_node_alloc;

	read_lock_bh(&pathtbl_resize_lock);
	memcpy(new_mpath->dst, dst, ETH_ALEN);
	memcpy(new_mpath->mpp, mpp, ETH_ALEN);
	new_mpath->sdata = sdata;
	new_mpath->flags = 0;
	skb_queue_head_init(&new_mpath->frame_queue);
	new_node->mpath = new_mpath;
	init_timer(&new_mpath->timer);
	new_mpath->exp_time = jiffies;
	spin_lock_init(&new_mpath->state_lock);

	tbl = resize_dereference_mpp_paths();

	hash_idx = mesh_table_hash(dst, sdata, tbl);
	bucket = &tbl->hash_buckets[hash_idx];

	spin_lock_bh(&tbl->hashwlock[hash_idx]);

	err = -EEXIST;
	hlist_for_each_entry(node, n, bucket, list) {
		mpath = node->mpath;
		if (mpath->sdata == sdata && memcmp(dst, mpath->dst, ETH_ALEN) == 0)
			goto err_exists;
	}

	hlist_add_head_rcu(&new_node->list, bucket);
	if (atomic_inc_return(&tbl->entries) >=
	    tbl->mean_chain_len * (tbl->hash_mask + 1))
		grow = 1;

	spin_unlock_bh(&tbl->hashwlock[hash_idx]);
	read_unlock_bh(&pathtbl_resize_lock);
	if (grow) {
		set_bit(MESH_WORK_GROW_MPP_TABLE,  &ifmsh->wrkq_flags);
		ieee80211_queue_work(&local->hw, &sdata->work);
	}
	return 0;

err_exists:
	spin_unlock_bh(&tbl->hashwlock[hash_idx]);
	read_unlock_bh(&pathtbl_resize_lock);
	kfree(new_node);
err_node_alloc:
	kfree(new_mpath);
err_path_alloc:
	return err;
}


/**
 * mesh_plink_broken - deactivates paths and sends perr when a link breaks
 *
 * @sta: broken peer link
 *
 * This function must be called from the rate control algorithm if enough
 * delivery errors suggest that a peer link is no longer usable.
 */
void mesh_plink_broken(struct sta_info *sta)
{
	struct mesh_table *tbl;
	static const u8 bcast[ETH_ALEN] = {0xff, 0xff, 0xff, 0xff, 0xff, 0xff};
	struct mesh_path *mpath;
	struct mpath_node *node;
	struct hlist_node *p;
	struct ieee80211_sub_if_data *sdata = sta->sdata;
	int i;
	__le16 reason = cpu_to_le16(WLAN_REASON_MESH_PATH_DEST_UNREACHABLE);

	rcu_read_lock();
	tbl = rcu_dereference(mesh_paths);
	for_each_mesh_entry(tbl, p, node, i) {
		mpath = node->mpath;
		if (rcu_dereference(mpath->next_hop) == sta &&
		    mpath->flags & MESH_PATH_ACTIVE &&
		    !(mpath->flags & MESH_PATH_FIXED)) {
			spin_lock_bh(&mpath->state_lock);
			mpath->flags &= ~MESH_PATH_ACTIVE;
			++mpath->sn;
			spin_unlock_bh(&mpath->state_lock);
			mesh_path_error_tx(sdata->u.mesh.mshcfg.element_ttl,
					mpath->dst, cpu_to_le32(mpath->sn),
					reason, bcast, sdata);
		}
	}
	rcu_read_unlock();
}

static void mesh_path_node_reclaim(struct rcu_head *rp)
{
	struct mpath_node *node = container_of(rp, struct mpath_node, rcu);
	struct ieee80211_sub_if_data *sdata = node->mpath->sdata;

	del_timer_sync(&node->mpath->timer);
	atomic_dec(&sdata->u.mesh.mpaths);
	kfree(node->mpath);
	kfree(node);
}

/* needs to be called with the corresponding hashwlock taken */
static void __mesh_path_del(struct mesh_table *tbl, struct mpath_node *node)
{
	struct mesh_path *mpath;
	mpath = node->mpath;
	spin_lock(&mpath->state_lock);
	mpath->flags |= MESH_PATH_RESOLVING;
	if (mpath->is_gate)
		mesh_gate_del(tbl, mpath);
	hlist_del_rcu(&node->list);
	call_rcu(&node->rcu, mesh_path_node_reclaim);
	spin_unlock(&mpath->state_lock);
	atomic_dec(&tbl->entries);
}

/**
 * mesh_path_flush_by_nexthop - Deletes mesh paths if their next hop matches
 *
 * @sta - mesh peer to match
 *
 * RCU notes: this function is called when a mesh plink transitions from
 * PLINK_ESTAB to any other state, since PLINK_ESTAB state is the only one that
 * allows path creation. This will happen before the sta can be freed (because
 * sta_info_destroy() calls this) so any reader in a rcu read block will be
 * protected against the plink disappearing.
 */
void mesh_path_flush_by_nexthop(struct sta_info *sta)
{
	struct mesh_table *tbl;
	struct mesh_path *mpath;
	struct mpath_node *node;
	struct hlist_node *p;
	int i;

	rcu_read_lock();
	read_lock_bh(&pathtbl_resize_lock);
	tbl = resize_dereference_mesh_paths();
	for_each_mesh_entry(tbl, p, node, i) {
		mpath = node->mpath;
		if (rcu_dereference(mpath->next_hop) == sta) {
			spin_lock_bh(&tbl->hashwlock[i]);
			__mesh_path_del(tbl, node);
			spin_unlock_bh(&tbl->hashwlock[i]);
		}
	}
	read_unlock_bh(&pathtbl_resize_lock);
	rcu_read_unlock();
}

static void table_flush_by_iface(struct mesh_table *tbl,
				 struct ieee80211_sub_if_data *sdata)
{
	struct mesh_path *mpath;
	struct mpath_node *node;
	struct hlist_node *p;
	int i;

	WARN_ON(!rcu_read_lock_held());
	for_each_mesh_entry(tbl, p, node, i) {
		mpath = node->mpath;
		if (mpath->sdata != sdata)
			continue;
		spin_lock_bh(&tbl->hashwlock[i]);
		__mesh_path_del(tbl, node);
		spin_unlock_bh(&tbl->hashwlock[i]);
	}
}

/**
 * mesh_path_flush_by_iface - Deletes all mesh paths associated with a given iface
 *
 * This function deletes both mesh paths as well as mesh portal paths.
 *
 * @sdata - interface data to match
 *
 */
void mesh_path_flush_by_iface(struct ieee80211_sub_if_data *sdata)
{
	struct mesh_table *tbl;

	rcu_read_lock();
	read_lock_bh(&pathtbl_resize_lock);
	tbl = resize_dereference_mesh_paths();
	table_flush_by_iface(tbl, sdata);
	tbl = resize_dereference_mpp_paths();
	table_flush_by_iface(tbl, sdata);
	read_unlock_bh(&pathtbl_resize_lock);
	rcu_read_unlock();
}

/**
 * mesh_path_del - delete a mesh path from the table
 *
 * @addr: dst address (ETH_ALEN length)
 * @sdata: local subif
 *
 * Returns: 0 if successful
 */
int mesh_path_del(u8 *addr, struct ieee80211_sub_if_data *sdata)
{
	struct mesh_table *tbl;
	struct mesh_path *mpath;
	struct mpath_node *node;
	struct hlist_head *bucket;
	struct hlist_node *n;
	int hash_idx;
	int err = 0;

	read_lock_bh(&pathtbl_resize_lock);
	tbl = resize_dereference_mesh_paths();
	hash_idx = mesh_table_hash(addr, sdata, tbl);
	bucket = &tbl->hash_buckets[hash_idx];

	spin_lock_bh(&tbl->hashwlock[hash_idx]);
	hlist_for_each_entry(node, n, bucket, list) {
		mpath = node->mpath;
		if (mpath->sdata == sdata &&
		    memcmp(addr, mpath->dst, ETH_ALEN) == 0) {
			__mesh_path_del(tbl, node);
			goto enddel;
		}
	}

	err = -ENXIO;
enddel:
	mesh_paths_generation++;
	spin_unlock_bh(&tbl->hashwlock[hash_idx]);
	read_unlock_bh(&pathtbl_resize_lock);
	return err;
}

/**
 * mesh_path_tx_pending - sends pending frames in a mesh path queue
 *
 * @mpath: mesh path to activate
 *
 * Locking: the state_lock of the mpath structure must NOT be held when calling
 * this function.
 */
void mesh_path_tx_pending(struct mesh_path *mpath)
{
	if (mpath->flags & MESH_PATH_ACTIVE)
		ieee80211_add_pending_skbs(mpath->sdata->local,
				&mpath->frame_queue);
}

/**
 * mesh_path_send_to_gates - sends pending frames to all known mesh gates
 *
 * @mpath: mesh path whose queue will be emptied
 *
 * If there is only one gate, the frames are transferred from the failed mpath
 * queue to that gate's queue.  If there are more than one gates, the frames
 * are copied from each gate to the next.  After frames are copied, the
 * mpath queues are emptied onto the transmission queue.
 */
int mesh_path_send_to_gates(struct mesh_path *mpath)
{
	struct ieee80211_sub_if_data *sdata = mpath->sdata;
	struct hlist_node *n;
	struct mesh_table *tbl;
	struct mesh_path *from_mpath = mpath;
	struct mpath_node *gate = NULL;
	bool copy = false;
	struct hlist_head *known_gates;

	rcu_read_lock();
	tbl = rcu_dereference(mesh_paths);
	known_gates = tbl->known_gates;
	rcu_read_unlock();

	if (!known_gates)
		return -EHOSTUNREACH;

	hlist_for_each_entry_rcu(gate, n, known_gates, list) {
		if (gate->mpath->sdata != sdata)
			continue;

		if (gate->mpath->flags & MESH_PATH_ACTIVE) {
			mpath_dbg("Forwarding to %pM\n", gate->mpath->dst);
			mesh_path_move_to_queue(gate->mpath, from_mpath, copy);
			from_mpath = gate->mpath;
			copy = true;
		} else {
			mpath_dbg("Not forwarding %p\n", gate->mpath);
			mpath_dbg("flags %x\n", gate->mpath->flags);
		}
	}

	hlist_for_each_entry_rcu(gate, n, known_gates, list)
		if (gate->mpath->sdata == sdata) {
			mpath_dbg("Sending to %pM\n", gate->mpath->dst);
			mesh_path_tx_pending(gate->mpath);
		}

	return (from_mpath == mpath) ? -EHOSTUNREACH : 0;
}

/**
 * mesh_path_discard_frame - discard a frame whose path could not be resolved
 *
 * @skb: frame to discard
 * @sdata: network subif the frame was to be sent through
 *
 * Locking: the function must me called within a rcu_read_lock region
 */
void mesh_path_discard_frame(struct sk_buff *skb,
			     struct ieee80211_sub_if_data *sdata)
{
	kfree_skb(skb);
	sdata->u.mesh.mshstats.dropped_frames_no_route++;
}

/**
 * mesh_path_flush_pending - free the pending queue of a mesh path
 *
 * @mpath: mesh path whose queue has to be freed
 *
 * Locking: the function must me called within a rcu_read_lock region
 */
void mesh_path_flush_pending(struct mesh_path *mpath)
{
	struct sk_buff *skb;

	while ((skb = skb_dequeue(&mpath->frame_queue)) != NULL)
		mesh_path_discard_frame(skb, mpath->sdata);
}

/**
 * mesh_path_fix_nexthop - force a specific next hop for a mesh path
 *
 * @mpath: the mesh path to modify
 * @next_hop: the next hop to force
 *
 * Locking: this function must be called holding mpath->state_lock
 */
void mesh_path_fix_nexthop(struct mesh_path *mpath, struct sta_info *next_hop)
{
	spin_lock_bh(&mpath->state_lock);
	mesh_path_assign_nexthop(mpath, next_hop);
	mpath->sn = 0xffff;
	mpath->metric = 0;
	mpath->hop_count = 0;
	mpath->exp_time = 0;
	mpath->flags |= MESH_PATH_FIXED;
	mesh_path_activate(mpath);
	spin_unlock_bh(&mpath->state_lock);
	mesh_path_tx_pending(mpath);
}

static void mesh_path_node_free(struct hlist_node *p, bool free_leafs)
{
	struct mesh_path *mpath;
	struct mpath_node *node = hlist_entry(p, struct mpath_node, list);
	mpath = node->mpath;
	hlist_del_rcu(p);
	if (free_leafs) {
		del_timer_sync(&mpath->timer);
		kfree(mpath);
	}
	kfree(node);
}

static int mesh_path_node_copy(struct hlist_node *p, struct mesh_table *newtbl)
{
	struct mesh_path *mpath;
	struct mpath_node *node, *new_node;
	u32 hash_idx;

	new_node = kmalloc(sizeof(struct mpath_node), GFP_ATOMIC);
	if (new_node == NULL)
		return -ENOMEM;

	node = hlist_entry(p, struct mpath_node, list);
	mpath = node->mpath;
	new_node->mpath = mpath;
	hash_idx = mesh_table_hash(mpath->dst, mpath->sdata, newtbl);
	hlist_add_head(&new_node->list,
			&newtbl->hash_buckets[hash_idx]);
	return 0;
}

int mesh_pathtbl_init(void)
{
	struct mesh_table *tbl_path, *tbl_mpp;
	int ret;

	tbl_path = mesh_table_alloc(INIT_PATHS_SIZE_ORDER);
	if (!tbl_path)
		return -ENOMEM;
	tbl_path->free_node = &mesh_path_node_free;
	tbl_path->copy_node = &mesh_path_node_copy;
	tbl_path->mean_chain_len = MEAN_CHAIN_LEN;
	tbl_path->known_gates = kzalloc(sizeof(struct hlist_head), GFP_ATOMIC);
	if (!tbl_path->known_gates) {
		ret = -ENOMEM;
		goto free_path;
	}
	INIT_HLIST_HEAD(tbl_path->known_gates);


	tbl_mpp = mesh_table_alloc(INIT_PATHS_SIZE_ORDER);
	if (!tbl_mpp) {
		ret = -ENOMEM;
		goto free_path;
	}
	tbl_mpp->free_node = &mesh_path_node_free;
	tbl_mpp->copy_node = &mesh_path_node_copy;
	tbl_mpp->mean_chain_len = MEAN_CHAIN_LEN;
	tbl_mpp->known_gates = kzalloc(sizeof(struct hlist_head), GFP_ATOMIC);
	if (!tbl_mpp->known_gates) {
		ret = -ENOMEM;
		goto free_mpp;
	}
	INIT_HLIST_HEAD(tbl_mpp->known_gates);

	/* Need no locking since this is during init */
	RCU_INIT_POINTER(mesh_paths, tbl_path);
	RCU_INIT_POINTER(mpp_paths, tbl_mpp);

	return 0;

free_mpp:
	mesh_table_free(tbl_mpp, true);
free_path:
	mesh_table_free(tbl_path, true);
	return ret;
}

void mesh_path_expire(struct ieee80211_sub_if_data *sdata)
{
	struct mesh_table *tbl;
	struct mesh_path *mpath;
	struct mpath_node *node;
	struct hlist_node *p;
	int i;

	rcu_read_lock();
	tbl = rcu_dereference(mesh_paths);
	for_each_mesh_entry(tbl, p, node, i) {
		if (node->mpath->sdata != sdata)
			continue;
		mpath = node->mpath;
		if ((!(mpath->flags & MESH_PATH_RESOLVING)) &&
		    (!(mpath->flags & MESH_PATH_FIXED)) &&
		     time_after(jiffies, mpath->exp_time + MESH_PATH_EXPIRE))
			mesh_path_del(mpath->dst, mpath->sdata);
	}
	rcu_read_unlock();
}

void mesh_pathtbl_unregister(void)
{
	/* no need for locking during exit path */
	mesh_table_free(rcu_dereference_protected(mesh_paths, 1), true);
	mesh_table_free(rcu_dereference_protected(mpp_paths, 1), true);
}