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TOMOYO Linux Cross Reference
Linux/net/ipv6/ip6_fib.c

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  1 /*
  2  *      Linux INET6 implementation
  3  *      Forwarding Information Database
  4  *
  5  *      Authors:
  6  *      Pedro Roque             <roque@di.fc.ul.pt>
  7  *
  8  *      This program is free software; you can redistribute it and/or
  9  *      modify it under the terms of the GNU General Public License
 10  *      as published by the Free Software Foundation; either version
 11  *      2 of the License, or (at your option) any later version.
 12  *
 13  *      Changes:
 14  *      Yuji SEKIYA @USAGI:     Support default route on router node;
 15  *                              remove ip6_null_entry from the top of
 16  *                              routing table.
 17  *      Ville Nuorvala:         Fixed routing subtrees.
 18  */
 19 
 20 #define pr_fmt(fmt) "IPv6: " fmt
 21 
 22 #include <linux/errno.h>
 23 #include <linux/types.h>
 24 #include <linux/net.h>
 25 #include <linux/route.h>
 26 #include <linux/netdevice.h>
 27 #include <linux/in6.h>
 28 #include <linux/init.h>
 29 #include <linux/list.h>
 30 #include <linux/slab.h>
 31 
 32 #include <net/ipv6.h>
 33 #include <net/ndisc.h>
 34 #include <net/addrconf.h>
 35 #include <net/lwtunnel.h>
 36 
 37 #include <net/ip6_fib.h>
 38 #include <net/ip6_route.h>
 39 
 40 #define RT6_DEBUG 2
 41 
 42 #if RT6_DEBUG >= 3
 43 #define RT6_TRACE(x...) pr_debug(x)
 44 #else
 45 #define RT6_TRACE(x...) do { ; } while (0)
 46 #endif
 47 
 48 static struct kmem_cache *fib6_node_kmem __read_mostly;
 49 
 50 struct fib6_cleaner {
 51         struct fib6_walker w;
 52         struct net *net;
 53         int (*func)(struct rt6_info *, void *arg);
 54         int sernum;
 55         void *arg;
 56 };
 57 
 58 #ifdef CONFIG_IPV6_SUBTREES
 59 #define FWS_INIT FWS_S
 60 #else
 61 #define FWS_INIT FWS_L
 62 #endif
 63 
 64 static void fib6_prune_clones(struct net *net, struct fib6_node *fn);
 65 static struct rt6_info *fib6_find_prefix(struct net *net, struct fib6_node *fn);
 66 static struct fib6_node *fib6_repair_tree(struct net *net, struct fib6_node *fn);
 67 static int fib6_walk(struct net *net, struct fib6_walker *w);
 68 static int fib6_walk_continue(struct fib6_walker *w);
 69 
 70 /*
 71  *      A routing update causes an increase of the serial number on the
 72  *      affected subtree. This allows for cached routes to be asynchronously
 73  *      tested when modifications are made to the destination cache as a
 74  *      result of redirects, path MTU changes, etc.
 75  */
 76 
 77 static void fib6_gc_timer_cb(unsigned long arg);
 78 
 79 #define FOR_WALKERS(net, w) \
 80         list_for_each_entry(w, &(net)->ipv6.fib6_walkers, lh)
 81 
 82 static void fib6_walker_link(struct net *net, struct fib6_walker *w)
 83 {
 84         write_lock_bh(&net->ipv6.fib6_walker_lock);
 85         list_add(&w->lh, &net->ipv6.fib6_walkers);
 86         write_unlock_bh(&net->ipv6.fib6_walker_lock);
 87 }
 88 
 89 static void fib6_walker_unlink(struct net *net, struct fib6_walker *w)
 90 {
 91         write_lock_bh(&net->ipv6.fib6_walker_lock);
 92         list_del(&w->lh);
 93         write_unlock_bh(&net->ipv6.fib6_walker_lock);
 94 }
 95 
 96 static int fib6_new_sernum(struct net *net)
 97 {
 98         int new, old;
 99 
100         do {
101                 old = atomic_read(&net->ipv6.fib6_sernum);
102                 new = old < INT_MAX ? old + 1 : 1;
103         } while (atomic_cmpxchg(&net->ipv6.fib6_sernum,
104                                 old, new) != old);
105         return new;
106 }
107 
108 enum {
109         FIB6_NO_SERNUM_CHANGE = 0,
110 };
111 
112 /*
113  *      Auxiliary address test functions for the radix tree.
114  *
115  *      These assume a 32bit processor (although it will work on
116  *      64bit processors)
117  */
118 
119 /*
120  *      test bit
121  */
122 #if defined(__LITTLE_ENDIAN)
123 # define BITOP_BE32_SWIZZLE     (0x1F & ~7)
124 #else
125 # define BITOP_BE32_SWIZZLE     0
126 #endif
127 
128 static __be32 addr_bit_set(const void *token, int fn_bit)
129 {
130         const __be32 *addr = token;
131         /*
132          * Here,
133          *      1 << ((~fn_bit ^ BITOP_BE32_SWIZZLE) & 0x1f)
134          * is optimized version of
135          *      htonl(1 << ((~fn_bit)&0x1F))
136          * See include/asm-generic/bitops/le.h.
137          */
138         return (__force __be32)(1 << ((~fn_bit ^ BITOP_BE32_SWIZZLE) & 0x1f)) &
139                addr[fn_bit >> 5];
140 }
141 
142 static struct fib6_node *node_alloc(void)
143 {
144         struct fib6_node *fn;
145 
146         fn = kmem_cache_zalloc(fib6_node_kmem, GFP_ATOMIC);
147 
148         return fn;
149 }
150 
151 static void node_free(struct fib6_node *fn)
152 {
153         kmem_cache_free(fib6_node_kmem, fn);
154 }
155 
156 static void rt6_rcu_free(struct rt6_info *rt)
157 {
158         call_rcu(&rt->dst.rcu_head, dst_rcu_free);
159 }
160 
161 static void rt6_free_pcpu(struct rt6_info *non_pcpu_rt)
162 {
163         int cpu;
164 
165         if (!non_pcpu_rt->rt6i_pcpu)
166                 return;
167 
168         for_each_possible_cpu(cpu) {
169                 struct rt6_info **ppcpu_rt;
170                 struct rt6_info *pcpu_rt;
171 
172                 ppcpu_rt = per_cpu_ptr(non_pcpu_rt->rt6i_pcpu, cpu);
173                 pcpu_rt = *ppcpu_rt;
174                 if (pcpu_rt) {
175                         rt6_rcu_free(pcpu_rt);
176                         *ppcpu_rt = NULL;
177                 }
178         }
179 
180         free_percpu(non_pcpu_rt->rt6i_pcpu);
181         non_pcpu_rt->rt6i_pcpu = NULL;
182 }
183 
184 static void rt6_release(struct rt6_info *rt)
185 {
186         if (atomic_dec_and_test(&rt->rt6i_ref)) {
187                 rt6_free_pcpu(rt);
188                 rt6_rcu_free(rt);
189         }
190 }
191 
192 static void fib6_link_table(struct net *net, struct fib6_table *tb)
193 {
194         unsigned int h;
195 
196         /*
197          * Initialize table lock at a single place to give lockdep a key,
198          * tables aren't visible prior to being linked to the list.
199          */
200         rwlock_init(&tb->tb6_lock);
201 
202         h = tb->tb6_id & (FIB6_TABLE_HASHSZ - 1);
203 
204         /*
205          * No protection necessary, this is the only list mutatation
206          * operation, tables never disappear once they exist.
207          */
208         hlist_add_head_rcu(&tb->tb6_hlist, &net->ipv6.fib_table_hash[h]);
209 }
210 
211 #ifdef CONFIG_IPV6_MULTIPLE_TABLES
212 
213 static struct fib6_table *fib6_alloc_table(struct net *net, u32 id)
214 {
215         struct fib6_table *table;
216 
217         table = kzalloc(sizeof(*table), GFP_ATOMIC);
218         if (table) {
219                 table->tb6_id = id;
220                 table->tb6_root.leaf = net->ipv6.ip6_null_entry;
221                 table->tb6_root.fn_flags = RTN_ROOT | RTN_TL_ROOT | RTN_RTINFO;
222                 inet_peer_base_init(&table->tb6_peers);
223         }
224 
225         return table;
226 }
227 
228 struct fib6_table *fib6_new_table(struct net *net, u32 id)
229 {
230         struct fib6_table *tb;
231 
232         if (id == 0)
233                 id = RT6_TABLE_MAIN;
234         tb = fib6_get_table(net, id);
235         if (tb)
236                 return tb;
237 
238         tb = fib6_alloc_table(net, id);
239         if (tb)
240                 fib6_link_table(net, tb);
241 
242         return tb;
243 }
244 EXPORT_SYMBOL_GPL(fib6_new_table);
245 
246 struct fib6_table *fib6_get_table(struct net *net, u32 id)
247 {
248         struct fib6_table *tb;
249         struct hlist_head *head;
250         unsigned int h;
251 
252         if (id == 0)
253                 id = RT6_TABLE_MAIN;
254         h = id & (FIB6_TABLE_HASHSZ - 1);
255         rcu_read_lock();
256         head = &net->ipv6.fib_table_hash[h];
257         hlist_for_each_entry_rcu(tb, head, tb6_hlist) {
258                 if (tb->tb6_id == id) {
259                         rcu_read_unlock();
260                         return tb;
261                 }
262         }
263         rcu_read_unlock();
264 
265         return NULL;
266 }
267 EXPORT_SYMBOL_GPL(fib6_get_table);
268 
269 static void __net_init fib6_tables_init(struct net *net)
270 {
271         fib6_link_table(net, net->ipv6.fib6_main_tbl);
272         fib6_link_table(net, net->ipv6.fib6_local_tbl);
273 }
274 #else
275 
276 struct fib6_table *fib6_new_table(struct net *net, u32 id)
277 {
278         return fib6_get_table(net, id);
279 }
280 
281 struct fib6_table *fib6_get_table(struct net *net, u32 id)
282 {
283           return net->ipv6.fib6_main_tbl;
284 }
285 
286 struct dst_entry *fib6_rule_lookup(struct net *net, struct flowi6 *fl6,
287                                    int flags, pol_lookup_t lookup)
288 {
289         struct rt6_info *rt;
290 
291         rt = lookup(net, net->ipv6.fib6_main_tbl, fl6, flags);
292         if (rt->rt6i_flags & RTF_REJECT &&
293             rt->dst.error == -EAGAIN) {
294                 ip6_rt_put(rt);
295                 rt = net->ipv6.ip6_null_entry;
296                 dst_hold(&rt->dst);
297         }
298 
299         return &rt->dst;
300 }
301 
302 static void __net_init fib6_tables_init(struct net *net)
303 {
304         fib6_link_table(net, net->ipv6.fib6_main_tbl);
305 }
306 
307 #endif
308 
309 static int fib6_dump_node(struct fib6_walker *w)
310 {
311         int res;
312         struct rt6_info *rt;
313 
314         for (rt = w->leaf; rt; rt = rt->dst.rt6_next) {
315                 res = rt6_dump_route(rt, w->args);
316                 if (res < 0) {
317                         /* Frame is full, suspend walking */
318                         w->leaf = rt;
319                         return 1;
320                 }
321         }
322         w->leaf = NULL;
323         return 0;
324 }
325 
326 static void fib6_dump_end(struct netlink_callback *cb)
327 {
328         struct net *net = sock_net(cb->skb->sk);
329         struct fib6_walker *w = (void *)cb->args[2];
330 
331         if (w) {
332                 if (cb->args[4]) {
333                         cb->args[4] = 0;
334                         fib6_walker_unlink(net, w);
335                 }
336                 cb->args[2] = 0;
337                 kfree(w);
338         }
339         cb->done = (void *)cb->args[3];
340         cb->args[1] = 3;
341 }
342 
343 static int fib6_dump_done(struct netlink_callback *cb)
344 {
345         fib6_dump_end(cb);
346         return cb->done ? cb->done(cb) : 0;
347 }
348 
349 static int fib6_dump_table(struct fib6_table *table, struct sk_buff *skb,
350                            struct netlink_callback *cb)
351 {
352         struct net *net = sock_net(skb->sk);
353         struct fib6_walker *w;
354         int res;
355 
356         w = (void *)cb->args[2];
357         w->root = &table->tb6_root;
358 
359         if (cb->args[4] == 0) {
360                 w->count = 0;
361                 w->skip = 0;
362 
363                 read_lock_bh(&table->tb6_lock);
364                 res = fib6_walk(net, w);
365                 read_unlock_bh(&table->tb6_lock);
366                 if (res > 0) {
367                         cb->args[4] = 1;
368                         cb->args[5] = w->root->fn_sernum;
369                 }
370         } else {
371                 if (cb->args[5] != w->root->fn_sernum) {
372                         /* Begin at the root if the tree changed */
373                         cb->args[5] = w->root->fn_sernum;
374                         w->state = FWS_INIT;
375                         w->node = w->root;
376                         w->skip = w->count;
377                 } else
378                         w->skip = 0;
379 
380                 read_lock_bh(&table->tb6_lock);
381                 res = fib6_walk_continue(w);
382                 read_unlock_bh(&table->tb6_lock);
383                 if (res <= 0) {
384                         fib6_walker_unlink(net, w);
385                         cb->args[4] = 0;
386                 }
387         }
388 
389         return res;
390 }
391 
392 static int inet6_dump_fib(struct sk_buff *skb, struct netlink_callback *cb)
393 {
394         struct net *net = sock_net(skb->sk);
395         unsigned int h, s_h;
396         unsigned int e = 0, s_e;
397         struct rt6_rtnl_dump_arg arg;
398         struct fib6_walker *w;
399         struct fib6_table *tb;
400         struct hlist_head *head;
401         int res = 0;
402 
403         s_h = cb->args[0];
404         s_e = cb->args[1];
405 
406         w = (void *)cb->args[2];
407         if (!w) {
408                 /* New dump:
409                  *
410                  * 1. hook callback destructor.
411                  */
412                 cb->args[3] = (long)cb->done;
413                 cb->done = fib6_dump_done;
414 
415                 /*
416                  * 2. allocate and initialize walker.
417                  */
418                 w = kzalloc(sizeof(*w), GFP_ATOMIC);
419                 if (!w)
420                         return -ENOMEM;
421                 w->func = fib6_dump_node;
422                 cb->args[2] = (long)w;
423         }
424 
425         arg.skb = skb;
426         arg.cb = cb;
427         arg.net = net;
428         w->args = &arg;
429 
430         rcu_read_lock();
431         for (h = s_h; h < FIB6_TABLE_HASHSZ; h++, s_e = 0) {
432                 e = 0;
433                 head = &net->ipv6.fib_table_hash[h];
434                 hlist_for_each_entry_rcu(tb, head, tb6_hlist) {
435                         if (e < s_e)
436                                 goto next;
437                         res = fib6_dump_table(tb, skb, cb);
438                         if (res != 0)
439                                 goto out;
440 next:
441                         e++;
442                 }
443         }
444 out:
445         rcu_read_unlock();
446         cb->args[1] = e;
447         cb->args[0] = h;
448 
449         res = res < 0 ? res : skb->len;
450         if (res <= 0)
451                 fib6_dump_end(cb);
452         return res;
453 }
454 
455 /*
456  *      Routing Table
457  *
458  *      return the appropriate node for a routing tree "add" operation
459  *      by either creating and inserting or by returning an existing
460  *      node.
461  */
462 
463 static struct fib6_node *fib6_add_1(struct fib6_node *root,
464                                      struct in6_addr *addr, int plen,
465                                      int offset, int allow_create,
466                                      int replace_required, int sernum)
467 {
468         struct fib6_node *fn, *in, *ln;
469         struct fib6_node *pn = NULL;
470         struct rt6key *key;
471         int     bit;
472         __be32  dir = 0;
473 
474         RT6_TRACE("fib6_add_1\n");
475 
476         /* insert node in tree */
477 
478         fn = root;
479 
480         do {
481                 key = (struct rt6key *)((u8 *)fn->leaf + offset);
482 
483                 /*
484                  *      Prefix match
485                  */
486                 if (plen < fn->fn_bit ||
487                     !ipv6_prefix_equal(&key->addr, addr, fn->fn_bit)) {
488                         if (!allow_create) {
489                                 if (replace_required) {
490                                         pr_warn("Can't replace route, no match found\n");
491                                         return ERR_PTR(-ENOENT);
492                                 }
493                                 pr_warn("NLM_F_CREATE should be set when creating new route\n");
494                         }
495                         goto insert_above;
496                 }
497 
498                 /*
499                  *      Exact match ?
500                  */
501 
502                 if (plen == fn->fn_bit) {
503                         /* clean up an intermediate node */
504                         if (!(fn->fn_flags & RTN_RTINFO)) {
505                                 rt6_release(fn->leaf);
506                                 fn->leaf = NULL;
507                         }
508 
509                         fn->fn_sernum = sernum;
510 
511                         return fn;
512                 }
513 
514                 /*
515                  *      We have more bits to go
516                  */
517 
518                 /* Try to walk down on tree. */
519                 fn->fn_sernum = sernum;
520                 dir = addr_bit_set(addr, fn->fn_bit);
521                 pn = fn;
522                 fn = dir ? fn->right : fn->left;
523         } while (fn);
524 
525         if (!allow_create) {
526                 /* We should not create new node because
527                  * NLM_F_REPLACE was specified without NLM_F_CREATE
528                  * I assume it is safe to require NLM_F_CREATE when
529                  * REPLACE flag is used! Later we may want to remove the
530                  * check for replace_required, because according
531                  * to netlink specification, NLM_F_CREATE
532                  * MUST be specified if new route is created.
533                  * That would keep IPv6 consistent with IPv4
534                  */
535                 if (replace_required) {
536                         pr_warn("Can't replace route, no match found\n");
537                         return ERR_PTR(-ENOENT);
538                 }
539                 pr_warn("NLM_F_CREATE should be set when creating new route\n");
540         }
541         /*
542          *      We walked to the bottom of tree.
543          *      Create new leaf node without children.
544          */
545 
546         ln = node_alloc();
547 
548         if (!ln)
549                 return ERR_PTR(-ENOMEM);
550         ln->fn_bit = plen;
551 
552         ln->parent = pn;
553         ln->fn_sernum = sernum;
554 
555         if (dir)
556                 pn->right = ln;
557         else
558                 pn->left  = ln;
559 
560         return ln;
561 
562 
563 insert_above:
564         /*
565          * split since we don't have a common prefix anymore or
566          * we have a less significant route.
567          * we've to insert an intermediate node on the list
568          * this new node will point to the one we need to create
569          * and the current
570          */
571 
572         pn = fn->parent;
573 
574         /* find 1st bit in difference between the 2 addrs.
575 
576            See comment in __ipv6_addr_diff: bit may be an invalid value,
577            but if it is >= plen, the value is ignored in any case.
578          */
579 
580         bit = __ipv6_addr_diff(addr, &key->addr, sizeof(*addr));
581 
582         /*
583          *              (intermediate)[in]
584          *                /        \
585          *      (new leaf node)[ln] (old node)[fn]
586          */
587         if (plen > bit) {
588                 in = node_alloc();
589                 ln = node_alloc();
590 
591                 if (!in || !ln) {
592                         if (in)
593                                 node_free(in);
594                         if (ln)
595                                 node_free(ln);
596                         return ERR_PTR(-ENOMEM);
597                 }
598 
599                 /*
600                  * new intermediate node.
601                  * RTN_RTINFO will
602                  * be off since that an address that chooses one of
603                  * the branches would not match less specific routes
604                  * in the other branch
605                  */
606 
607                 in->fn_bit = bit;
608 
609                 in->parent = pn;
610                 in->leaf = fn->leaf;
611                 atomic_inc(&in->leaf->rt6i_ref);
612 
613                 in->fn_sernum = sernum;
614 
615                 /* update parent pointer */
616                 if (dir)
617                         pn->right = in;
618                 else
619                         pn->left  = in;
620 
621                 ln->fn_bit = plen;
622 
623                 ln->parent = in;
624                 fn->parent = in;
625 
626                 ln->fn_sernum = sernum;
627 
628                 if (addr_bit_set(addr, bit)) {
629                         in->right = ln;
630                         in->left  = fn;
631                 } else {
632                         in->left  = ln;
633                         in->right = fn;
634                 }
635         } else { /* plen <= bit */
636 
637                 /*
638                  *              (new leaf node)[ln]
639                  *                /        \
640                  *           (old node)[fn] NULL
641                  */
642 
643                 ln = node_alloc();
644 
645                 if (!ln)
646                         return ERR_PTR(-ENOMEM);
647 
648                 ln->fn_bit = plen;
649 
650                 ln->parent = pn;
651 
652                 ln->fn_sernum = sernum;
653 
654                 if (dir)
655                         pn->right = ln;
656                 else
657                         pn->left  = ln;
658 
659                 if (addr_bit_set(&key->addr, plen))
660                         ln->right = fn;
661                 else
662                         ln->left  = fn;
663 
664                 fn->parent = ln;
665         }
666         return ln;
667 }
668 
669 static bool rt6_qualify_for_ecmp(struct rt6_info *rt)
670 {
671         return (rt->rt6i_flags & (RTF_GATEWAY|RTF_ADDRCONF|RTF_DYNAMIC)) ==
672                RTF_GATEWAY;
673 }
674 
675 static void fib6_copy_metrics(u32 *mp, const struct mx6_config *mxc)
676 {
677         int i;
678 
679         for (i = 0; i < RTAX_MAX; i++) {
680                 if (test_bit(i, mxc->mx_valid))
681                         mp[i] = mxc->mx[i];
682         }
683 }
684 
685 static int fib6_commit_metrics(struct dst_entry *dst, struct mx6_config *mxc)
686 {
687         if (!mxc->mx)
688                 return 0;
689 
690         if (dst->flags & DST_HOST) {
691                 u32 *mp = dst_metrics_write_ptr(dst);
692 
693                 if (unlikely(!mp))
694                         return -ENOMEM;
695 
696                 fib6_copy_metrics(mp, mxc);
697         } else {
698                 dst_init_metrics(dst, mxc->mx, false);
699 
700                 /* We've stolen mx now. */
701                 mxc->mx = NULL;
702         }
703 
704         return 0;
705 }
706 
707 static void fib6_purge_rt(struct rt6_info *rt, struct fib6_node *fn,
708                           struct net *net)
709 {
710         if (atomic_read(&rt->rt6i_ref) != 1) {
711                 /* This route is used as dummy address holder in some split
712                  * nodes. It is not leaked, but it still holds other resources,
713                  * which must be released in time. So, scan ascendant nodes
714                  * and replace dummy references to this route with references
715                  * to still alive ones.
716                  */
717                 while (fn) {
718                         if (!(fn->fn_flags & RTN_RTINFO) && fn->leaf == rt) {
719                                 fn->leaf = fib6_find_prefix(net, fn);
720                                 atomic_inc(&fn->leaf->rt6i_ref);
721                                 rt6_release(rt);
722                         }
723                         fn = fn->parent;
724                 }
725                 /* No more references are possible at this point. */
726                 BUG_ON(atomic_read(&rt->rt6i_ref) != 1);
727         }
728 }
729 
730 /*
731  *      Insert routing information in a node.
732  */
733 
734 static int fib6_add_rt2node(struct fib6_node *fn, struct rt6_info *rt,
735                             struct nl_info *info, struct mx6_config *mxc)
736 {
737         struct rt6_info *iter = NULL;
738         struct rt6_info **ins;
739         struct rt6_info **fallback_ins = NULL;
740         int replace = (info->nlh &&
741                        (info->nlh->nlmsg_flags & NLM_F_REPLACE));
742         int add = (!info->nlh ||
743                    (info->nlh->nlmsg_flags & NLM_F_CREATE));
744         int found = 0;
745         bool rt_can_ecmp = rt6_qualify_for_ecmp(rt);
746         int err;
747 
748         ins = &fn->leaf;
749 
750         for (iter = fn->leaf; iter; iter = iter->dst.rt6_next) {
751                 /*
752                  *      Search for duplicates
753                  */
754 
755                 if (iter->rt6i_metric == rt->rt6i_metric) {
756                         /*
757                          *      Same priority level
758                          */
759                         if (info->nlh &&
760                             (info->nlh->nlmsg_flags & NLM_F_EXCL))
761                                 return -EEXIST;
762                         if (replace) {
763                                 if (rt_can_ecmp == rt6_qualify_for_ecmp(iter)) {
764                                         found++;
765                                         break;
766                                 }
767                                 if (rt_can_ecmp)
768                                         fallback_ins = fallback_ins ?: ins;
769                                 goto next_iter;
770                         }
771 
772                         if (iter->dst.dev == rt->dst.dev &&
773                             iter->rt6i_idev == rt->rt6i_idev &&
774                             ipv6_addr_equal(&iter->rt6i_gateway,
775                                             &rt->rt6i_gateway)) {
776                                 if (rt->rt6i_nsiblings)
777                                         rt->rt6i_nsiblings = 0;
778                                 if (!(iter->rt6i_flags & RTF_EXPIRES))
779                                         return -EEXIST;
780                                 if (!(rt->rt6i_flags & RTF_EXPIRES))
781                                         rt6_clean_expires(iter);
782                                 else
783                                         rt6_set_expires(iter, rt->dst.expires);
784                                 iter->rt6i_pmtu = rt->rt6i_pmtu;
785                                 return -EEXIST;
786                         }
787                         /* If we have the same destination and the same metric,
788                          * but not the same gateway, then the route we try to
789                          * add is sibling to this route, increment our counter
790                          * of siblings, and later we will add our route to the
791                          * list.
792                          * Only static routes (which don't have flag
793                          * RTF_EXPIRES) are used for ECMPv6.
794                          *
795                          * To avoid long list, we only had siblings if the
796                          * route have a gateway.
797                          */
798                         if (rt_can_ecmp &&
799                             rt6_qualify_for_ecmp(iter))
800                                 rt->rt6i_nsiblings++;
801                 }
802 
803                 if (iter->rt6i_metric > rt->rt6i_metric)
804                         break;
805 
806 next_iter:
807                 ins = &iter->dst.rt6_next;
808         }
809 
810         if (fallback_ins && !found) {
811                 /* No ECMP-able route found, replace first non-ECMP one */
812                 ins = fallback_ins;
813                 iter = *ins;
814                 found++;
815         }
816 
817         /* Reset round-robin state, if necessary */
818         if (ins == &fn->leaf)
819                 fn->rr_ptr = NULL;
820 
821         /* Link this route to others same route. */
822         if (rt->rt6i_nsiblings) {
823                 unsigned int rt6i_nsiblings;
824                 struct rt6_info *sibling, *temp_sibling;
825 
826                 /* Find the first route that have the same metric */
827                 sibling = fn->leaf;
828                 while (sibling) {
829                         if (sibling->rt6i_metric == rt->rt6i_metric &&
830                             rt6_qualify_for_ecmp(sibling)) {
831                                 list_add_tail(&rt->rt6i_siblings,
832                                               &sibling->rt6i_siblings);
833                                 break;
834                         }
835                         sibling = sibling->dst.rt6_next;
836                 }
837                 /* For each sibling in the list, increment the counter of
838                  * siblings. BUG() if counters does not match, list of siblings
839                  * is broken!
840                  */
841                 rt6i_nsiblings = 0;
842                 list_for_each_entry_safe(sibling, temp_sibling,
843                                          &rt->rt6i_siblings, rt6i_siblings) {
844                         sibling->rt6i_nsiblings++;
845                         BUG_ON(sibling->rt6i_nsiblings != rt->rt6i_nsiblings);
846                         rt6i_nsiblings++;
847                 }
848                 BUG_ON(rt6i_nsiblings != rt->rt6i_nsiblings);
849         }
850 
851         /*
852          *      insert node
853          */
854         if (!replace) {
855                 if (!add)
856                         pr_warn("NLM_F_CREATE should be set when creating new route\n");
857 
858 add:
859                 err = fib6_commit_metrics(&rt->dst, mxc);
860                 if (err)
861                         return err;
862 
863                 rt->dst.rt6_next = iter;
864                 *ins = rt;
865                 rt->rt6i_node = fn;
866                 atomic_inc(&rt->rt6i_ref);
867                 inet6_rt_notify(RTM_NEWROUTE, rt, info, 0);
868                 info->nl_net->ipv6.rt6_stats->fib_rt_entries++;
869 
870                 if (!(fn->fn_flags & RTN_RTINFO)) {
871                         info->nl_net->ipv6.rt6_stats->fib_route_nodes++;
872                         fn->fn_flags |= RTN_RTINFO;
873                 }
874 
875         } else {
876                 int nsiblings;
877 
878                 if (!found) {
879                         if (add)
880                                 goto add;
881                         pr_warn("NLM_F_REPLACE set, but no existing node found!\n");
882                         return -ENOENT;
883                 }
884 
885                 err = fib6_commit_metrics(&rt->dst, mxc);
886                 if (err)
887                         return err;
888 
889                 *ins = rt;
890                 rt->rt6i_node = fn;
891                 rt->dst.rt6_next = iter->dst.rt6_next;
892                 atomic_inc(&rt->rt6i_ref);
893                 inet6_rt_notify(RTM_NEWROUTE, rt, info, NLM_F_REPLACE);
894                 if (!(fn->fn_flags & RTN_RTINFO)) {
895                         info->nl_net->ipv6.rt6_stats->fib_route_nodes++;
896                         fn->fn_flags |= RTN_RTINFO;
897                 }
898                 nsiblings = iter->rt6i_nsiblings;
899                 fib6_purge_rt(iter, fn, info->nl_net);
900                 rt6_release(iter);
901 
902                 if (nsiblings) {
903                         /* Replacing an ECMP route, remove all siblings */
904                         ins = &rt->dst.rt6_next;
905                         iter = *ins;
906                         while (iter) {
907                                 if (rt6_qualify_for_ecmp(iter)) {
908                                         *ins = iter->dst.rt6_next;
909                                         fib6_purge_rt(iter, fn, info->nl_net);
910                                         rt6_release(iter);
911                                         nsiblings--;
912                                 } else {
913                                         ins = &iter->dst.rt6_next;
914                                 }
915                                 iter = *ins;
916                         }
917                         WARN_ON(nsiblings != 0);
918                 }
919         }
920 
921         return 0;
922 }
923 
924 static void fib6_start_gc(struct net *net, struct rt6_info *rt)
925 {
926         if (!timer_pending(&net->ipv6.ip6_fib_timer) &&
927             (rt->rt6i_flags & (RTF_EXPIRES | RTF_CACHE)))
928                 mod_timer(&net->ipv6.ip6_fib_timer,
929                           jiffies + net->ipv6.sysctl.ip6_rt_gc_interval);
930 }
931 
932 void fib6_force_start_gc(struct net *net)
933 {
934         if (!timer_pending(&net->ipv6.ip6_fib_timer))
935                 mod_timer(&net->ipv6.ip6_fib_timer,
936                           jiffies + net->ipv6.sysctl.ip6_rt_gc_interval);
937 }
938 
939 /*
940  *      Add routing information to the routing tree.
941  *      <destination addr>/<source addr>
942  *      with source addr info in sub-trees
943  */
944 
945 int fib6_add(struct fib6_node *root, struct rt6_info *rt,
946              struct nl_info *info, struct mx6_config *mxc)
947 {
948         struct fib6_node *fn, *pn = NULL;
949         int err = -ENOMEM;
950         int allow_create = 1;
951         int replace_required = 0;
952         int sernum = fib6_new_sernum(info->nl_net);
953 
954         if (WARN_ON_ONCE((rt->dst.flags & DST_NOCACHE) &&
955                          !atomic_read(&rt->dst.__refcnt)))
956                 return -EINVAL;
957 
958         if (info->nlh) {
959                 if (!(info->nlh->nlmsg_flags & NLM_F_CREATE))
960                         allow_create = 0;
961                 if (info->nlh->nlmsg_flags & NLM_F_REPLACE)
962                         replace_required = 1;
963         }
964         if (!allow_create && !replace_required)
965                 pr_warn("RTM_NEWROUTE with no NLM_F_CREATE or NLM_F_REPLACE\n");
966 
967         fn = fib6_add_1(root, &rt->rt6i_dst.addr, rt->rt6i_dst.plen,
968                         offsetof(struct rt6_info, rt6i_dst), allow_create,
969                         replace_required, sernum);
970         if (IS_ERR(fn)) {
971                 err = PTR_ERR(fn);
972                 fn = NULL;
973                 goto out;
974         }
975 
976         pn = fn;
977 
978 #ifdef CONFIG_IPV6_SUBTREES
979         if (rt->rt6i_src.plen) {
980                 struct fib6_node *sn;
981 
982                 if (!fn->subtree) {
983                         struct fib6_node *sfn;
984 
985                         /*
986                          * Create subtree.
987                          *
988                          *              fn[main tree]
989                          *              |
990                          *              sfn[subtree root]
991                          *                 \
992                          *                  sn[new leaf node]
993                          */
994 
995                         /* Create subtree root node */
996                         sfn = node_alloc();
997                         if (!sfn)
998                                 goto st_failure;
999 
1000                         sfn->leaf = info->nl_net->ipv6.ip6_null_entry;
1001                         atomic_inc(&info->nl_net->ipv6.ip6_null_entry->rt6i_ref);
1002                         sfn->fn_flags = RTN_ROOT;
1003                         sfn->fn_sernum = sernum;
1004 
1005                         /* Now add the first leaf node to new subtree */
1006 
1007                         sn = fib6_add_1(sfn, &rt->rt6i_src.addr,
1008                                         rt->rt6i_src.plen,
1009                                         offsetof(struct rt6_info, rt6i_src),
1010                                         allow_create, replace_required, sernum);
1011 
1012                         if (IS_ERR(sn)) {
1013                                 /* If it is failed, discard just allocated
1014                                    root, and then (in st_failure) stale node
1015                                    in main tree.
1016                                  */
1017                                 node_free(sfn);
1018                                 err = PTR_ERR(sn);
1019                                 goto st_failure;
1020                         }
1021 
1022                         /* Now link new subtree to main tree */
1023                         sfn->parent = fn;
1024                         fn->subtree = sfn;
1025                 } else {
1026                         sn = fib6_add_1(fn->subtree, &rt->rt6i_src.addr,
1027                                         rt->rt6i_src.plen,
1028                                         offsetof(struct rt6_info, rt6i_src),
1029                                         allow_create, replace_required, sernum);
1030 
1031                         if (IS_ERR(sn)) {
1032                                 err = PTR_ERR(sn);
1033                                 goto st_failure;
1034                         }
1035                 }
1036 
1037                 if (!fn->leaf) {
1038                         fn->leaf = rt;
1039                         atomic_inc(&rt->rt6i_ref);
1040                 }
1041                 fn = sn;
1042         }
1043 #endif
1044 
1045         err = fib6_add_rt2node(fn, rt, info, mxc);
1046         if (!err) {
1047                 fib6_start_gc(info->nl_net, rt);
1048                 if (!(rt->rt6i_flags & RTF_CACHE))
1049                         fib6_prune_clones(info->nl_net, pn);
1050                 rt->dst.flags &= ~DST_NOCACHE;
1051         }
1052 
1053 out:
1054         if (err) {
1055 #ifdef CONFIG_IPV6_SUBTREES
1056                 /*
1057                  * If fib6_add_1 has cleared the old leaf pointer in the
1058                  * super-tree leaf node we have to find a new one for it.
1059                  */
1060                 if (pn != fn && pn->leaf == rt) {
1061                         pn->leaf = NULL;
1062                         atomic_dec(&rt->rt6i_ref);
1063                 }
1064                 if (pn != fn && !pn->leaf && !(pn->fn_flags & RTN_RTINFO)) {
1065                         pn->leaf = fib6_find_prefix(info->nl_net, pn);
1066 #if RT6_DEBUG >= 2
1067                         if (!pn->leaf) {
1068                                 WARN_ON(pn->leaf == NULL);
1069                                 pn->leaf = info->nl_net->ipv6.ip6_null_entry;
1070                         }
1071 #endif
1072                         atomic_inc(&pn->leaf->rt6i_ref);
1073                 }
1074 #endif
1075                 if (!(rt->dst.flags & DST_NOCACHE))
1076                         dst_free(&rt->dst);
1077         }
1078         return err;
1079 
1080 #ifdef CONFIG_IPV6_SUBTREES
1081         /* Subtree creation failed, probably main tree node
1082            is orphan. If it is, shoot it.
1083          */
1084 st_failure:
1085         if (fn && !(fn->fn_flags & (RTN_RTINFO|RTN_ROOT)))
1086                 fib6_repair_tree(info->nl_net, fn);
1087         if (!(rt->dst.flags & DST_NOCACHE))
1088                 dst_free(&rt->dst);
1089         return err;
1090 #endif
1091 }
1092 
1093 /*
1094  *      Routing tree lookup
1095  *
1096  */
1097 
1098 struct lookup_args {
1099         int                     offset;         /* key offset on rt6_info       */
1100         const struct in6_addr   *addr;          /* search key                   */
1101 };
1102 
1103 static struct fib6_node *fib6_lookup_1(struct fib6_node *root,
1104                                        struct lookup_args *args)
1105 {
1106         struct fib6_node *fn;
1107         __be32 dir;
1108 
1109         if (unlikely(args->offset == 0))
1110                 return NULL;
1111 
1112         /*
1113          *      Descend on a tree
1114          */
1115 
1116         fn = root;
1117 
1118         for (;;) {
1119                 struct fib6_node *next;
1120 
1121                 dir = addr_bit_set(args->addr, fn->fn_bit);
1122 
1123                 next = dir ? fn->right : fn->left;
1124 
1125                 if (next) {
1126                         fn = next;
1127                         continue;
1128                 }
1129                 break;
1130         }
1131 
1132         while (fn) {
1133                 if (FIB6_SUBTREE(fn) || fn->fn_flags & RTN_RTINFO) {
1134                         struct rt6key *key;
1135 
1136                         key = (struct rt6key *) ((u8 *) fn->leaf +
1137                                                  args->offset);
1138 
1139                         if (ipv6_prefix_equal(&key->addr, args->addr, key->plen)) {
1140 #ifdef CONFIG_IPV6_SUBTREES
1141                                 if (fn->subtree) {
1142                                         struct fib6_node *sfn;
1143                                         sfn = fib6_lookup_1(fn->subtree,
1144                                                             args + 1);
1145                                         if (!sfn)
1146                                                 goto backtrack;
1147                                         fn = sfn;
1148                                 }
1149 #endif
1150                                 if (fn->fn_flags & RTN_RTINFO)
1151                                         return fn;
1152                         }
1153                 }
1154 #ifdef CONFIG_IPV6_SUBTREES
1155 backtrack:
1156 #endif
1157                 if (fn->fn_flags & RTN_ROOT)
1158                         break;
1159 
1160                 fn = fn->parent;
1161         }
1162 
1163         return NULL;
1164 }
1165 
1166 struct fib6_node *fib6_lookup(struct fib6_node *root, const struct in6_addr *daddr,
1167                               const struct in6_addr *saddr)
1168 {
1169         struct fib6_node *fn;
1170         struct lookup_args args[] = {
1171                 {
1172                         .offset = offsetof(struct rt6_info, rt6i_dst),
1173                         .addr = daddr,
1174                 },
1175 #ifdef CONFIG_IPV6_SUBTREES
1176                 {
1177                         .offset = offsetof(struct rt6_info, rt6i_src),
1178                         .addr = saddr,
1179                 },
1180 #endif
1181                 {
1182                         .offset = 0,    /* sentinel */
1183                 }
1184         };
1185 
1186         fn = fib6_lookup_1(root, daddr ? args : args + 1);
1187         if (!fn || fn->fn_flags & RTN_TL_ROOT)
1188                 fn = root;
1189 
1190         return fn;
1191 }
1192 
1193 /*
1194  *      Get node with specified destination prefix (and source prefix,
1195  *      if subtrees are used)
1196  */
1197 
1198 
1199 static struct fib6_node *fib6_locate_1(struct fib6_node *root,
1200                                        const struct in6_addr *addr,
1201                                        int plen, int offset)
1202 {
1203         struct fib6_node *fn;
1204 
1205         for (fn = root; fn ; ) {
1206                 struct rt6key *key = (struct rt6key *)((u8 *)fn->leaf + offset);
1207 
1208                 /*
1209                  *      Prefix match
1210                  */
1211                 if (plen < fn->fn_bit ||
1212                     !ipv6_prefix_equal(&key->addr, addr, fn->fn_bit))
1213                         return NULL;
1214 
1215                 if (plen == fn->fn_bit)
1216                         return fn;
1217 
1218                 /*
1219                  *      We have more bits to go
1220                  */
1221                 if (addr_bit_set(addr, fn->fn_bit))
1222                         fn = fn->right;
1223                 else
1224                         fn = fn->left;
1225         }
1226         return NULL;
1227 }
1228 
1229 struct fib6_node *fib6_locate(struct fib6_node *root,
1230                               const struct in6_addr *daddr, int dst_len,
1231                               const struct in6_addr *saddr, int src_len)
1232 {
1233         struct fib6_node *fn;
1234 
1235         fn = fib6_locate_1(root, daddr, dst_len,
1236                            offsetof(struct rt6_info, rt6i_dst));
1237 
1238 #ifdef CONFIG_IPV6_SUBTREES
1239         if (src_len) {
1240                 WARN_ON(saddr == NULL);
1241                 if (fn && fn->subtree)
1242                         fn = fib6_locate_1(fn->subtree, saddr, src_len,
1243                                            offsetof(struct rt6_info, rt6i_src));
1244         }
1245 #endif
1246 
1247         if (fn && fn->fn_flags & RTN_RTINFO)
1248                 return fn;
1249 
1250         return NULL;
1251 }
1252 
1253 
1254 /*
1255  *      Deletion
1256  *
1257  */
1258 
1259 static struct rt6_info *fib6_find_prefix(struct net *net, struct fib6_node *fn)
1260 {
1261         if (fn->fn_flags & RTN_ROOT)
1262                 return net->ipv6.ip6_null_entry;
1263 
1264         while (fn) {
1265                 if (fn->left)
1266                         return fn->left->leaf;
1267                 if (fn->right)
1268                         return fn->right->leaf;
1269 
1270                 fn = FIB6_SUBTREE(fn);
1271         }
1272         return NULL;
1273 }
1274 
1275 /*
1276  *      Called to trim the tree of intermediate nodes when possible. "fn"
1277  *      is the node we want to try and remove.
1278  */
1279 
1280 static struct fib6_node *fib6_repair_tree(struct net *net,
1281                                            struct fib6_node *fn)
1282 {
1283         int children;
1284         int nstate;
1285         struct fib6_node *child, *pn;
1286         struct fib6_walker *w;
1287         int iter = 0;
1288 
1289         for (;;) {
1290                 RT6_TRACE("fixing tree: plen=%d iter=%d\n", fn->fn_bit, iter);
1291                 iter++;
1292 
1293                 WARN_ON(fn->fn_flags & RTN_RTINFO);
1294                 WARN_ON(fn->fn_flags & RTN_TL_ROOT);
1295                 WARN_ON(fn->leaf);
1296 
1297                 children = 0;
1298                 child = NULL;
1299                 if (fn->right)
1300                         child = fn->right, children |= 1;
1301                 if (fn->left)
1302                         child = fn->left, children |= 2;
1303 
1304                 if (children == 3 || FIB6_SUBTREE(fn)
1305 #ifdef CONFIG_IPV6_SUBTREES
1306                     /* Subtree root (i.e. fn) may have one child */
1307                     || (children && fn->fn_flags & RTN_ROOT)
1308 #endif
1309                     ) {
1310                         fn->leaf = fib6_find_prefix(net, fn);
1311 #if RT6_DEBUG >= 2
1312                         if (!fn->leaf) {
1313                                 WARN_ON(!fn->leaf);
1314                                 fn->leaf = net->ipv6.ip6_null_entry;
1315                         }
1316 #endif
1317                         atomic_inc(&fn->leaf->rt6i_ref);
1318                         return fn->parent;
1319                 }
1320 
1321                 pn = fn->parent;
1322 #ifdef CONFIG_IPV6_SUBTREES
1323                 if (FIB6_SUBTREE(pn) == fn) {
1324                         WARN_ON(!(fn->fn_flags & RTN_ROOT));
1325                         FIB6_SUBTREE(pn) = NULL;
1326                         nstate = FWS_L;
1327                 } else {
1328                         WARN_ON(fn->fn_flags & RTN_ROOT);
1329 #endif
1330                         if (pn->right == fn)
1331                                 pn->right = child;
1332                         else if (pn->left == fn)
1333                                 pn->left = child;
1334 #if RT6_DEBUG >= 2
1335                         else
1336                                 WARN_ON(1);
1337 #endif
1338                         if (child)
1339                                 child->parent = pn;
1340                         nstate = FWS_R;
1341 #ifdef CONFIG_IPV6_SUBTREES
1342                 }
1343 #endif
1344 
1345                 read_lock(&net->ipv6.fib6_walker_lock);
1346                 FOR_WALKERS(net, w) {
1347                         if (!child) {
1348                                 if (w->root == fn) {
1349                                         w->root = w->node = NULL;
1350                                         RT6_TRACE("W %p adjusted by delroot 1\n", w);
1351                                 } else if (w->node == fn) {
1352                                         RT6_TRACE("W %p adjusted by delnode 1, s=%d/%d\n", w, w->state, nstate);
1353                                         w->node = pn;
1354                                         w->state = nstate;
1355                                 }
1356                         } else {
1357                                 if (w->root == fn) {
1358                                         w->root = child;
1359                                         RT6_TRACE("W %p adjusted by delroot 2\n", w);
1360                                 }
1361                                 if (w->node == fn) {
1362                                         w->node = child;
1363                                         if (children&2) {
1364                                                 RT6_TRACE("W %p adjusted by delnode 2, s=%d\n", w, w->state);
1365                                                 w->state = w->state >= FWS_R ? FWS_U : FWS_INIT;
1366                                         } else {
1367                                                 RT6_TRACE("W %p adjusted by delnode 2, s=%d\n", w, w->state);
1368                                                 w->state = w->state >= FWS_C ? FWS_U : FWS_INIT;
1369                                         }
1370                                 }
1371                         }
1372                 }
1373                 read_unlock(&net->ipv6.fib6_walker_lock);
1374 
1375                 node_free(fn);
1376                 if (pn->fn_flags & RTN_RTINFO || FIB6_SUBTREE(pn))
1377                         return pn;
1378 
1379                 rt6_release(pn->leaf);
1380                 pn->leaf = NULL;
1381                 fn = pn;
1382         }
1383 }
1384 
1385 static void fib6_del_route(struct fib6_node *fn, struct rt6_info **rtp,
1386                            struct nl_info *info)
1387 {
1388         struct fib6_walker *w;
1389         struct rt6_info *rt = *rtp;
1390         struct net *net = info->nl_net;
1391 
1392         RT6_TRACE("fib6_del_route\n");
1393 
1394         /* Unlink it */
1395         *rtp = rt->dst.rt6_next;
1396         rt->rt6i_node = NULL;
1397         net->ipv6.rt6_stats->fib_rt_entries--;
1398         net->ipv6.rt6_stats->fib_discarded_routes++;
1399 
1400         /* Reset round-robin state, if necessary */
1401         if (fn->rr_ptr == rt)
1402                 fn->rr_ptr = NULL;
1403 
1404         /* Remove this entry from other siblings */
1405         if (rt->rt6i_nsiblings) {
1406                 struct rt6_info *sibling, *next_sibling;
1407 
1408                 list_for_each_entry_safe(sibling, next_sibling,
1409                                          &rt->rt6i_siblings, rt6i_siblings)
1410                         sibling->rt6i_nsiblings--;
1411                 rt->rt6i_nsiblings = 0;
1412                 list_del_init(&rt->rt6i_siblings);
1413         }
1414 
1415         /* Adjust walkers */
1416         read_lock(&net->ipv6.fib6_walker_lock);
1417         FOR_WALKERS(net, w) {
1418                 if (w->state == FWS_C && w->leaf == rt) {
1419                         RT6_TRACE("walker %p adjusted by delroute\n", w);
1420                         w->leaf = rt->dst.rt6_next;
1421                         if (!w->leaf)
1422                                 w->state = FWS_U;
1423                 }
1424         }
1425         read_unlock(&net->ipv6.fib6_walker_lock);
1426 
1427         rt->dst.rt6_next = NULL;
1428 
1429         /* If it was last route, expunge its radix tree node */
1430         if (!fn->leaf) {
1431                 fn->fn_flags &= ~RTN_RTINFO;
1432                 net->ipv6.rt6_stats->fib_route_nodes--;
1433                 fn = fib6_repair_tree(net, fn);
1434         }
1435 
1436         fib6_purge_rt(rt, fn, net);
1437 
1438         inet6_rt_notify(RTM_DELROUTE, rt, info, 0);
1439         rt6_release(rt);
1440 }
1441 
1442 int fib6_del(struct rt6_info *rt, struct nl_info *info)
1443 {
1444         struct net *net = info->nl_net;
1445         struct fib6_node *fn = rt->rt6i_node;
1446         struct rt6_info **rtp;
1447 
1448 #if RT6_DEBUG >= 2
1449         if (rt->dst.obsolete > 0) {
1450                 WARN_ON(fn);
1451                 return -ENOENT;
1452         }
1453 #endif
1454         if (!fn || rt == net->ipv6.ip6_null_entry)
1455                 return -ENOENT;
1456 
1457         WARN_ON(!(fn->fn_flags & RTN_RTINFO));
1458 
1459         if (!(rt->rt6i_flags & RTF_CACHE)) {
1460                 struct fib6_node *pn = fn;
1461 #ifdef CONFIG_IPV6_SUBTREES
1462                 /* clones of this route might be in another subtree */
1463                 if (rt->rt6i_src.plen) {
1464                         while (!(pn->fn_flags & RTN_ROOT))
1465                                 pn = pn->parent;
1466                         pn = pn->parent;
1467                 }
1468 #endif
1469                 fib6_prune_clones(info->nl_net, pn);
1470         }
1471 
1472         /*
1473          *      Walk the leaf entries looking for ourself
1474          */
1475 
1476         for (rtp = &fn->leaf; *rtp; rtp = &(*rtp)->dst.rt6_next) {
1477                 if (*rtp == rt) {
1478                         fib6_del_route(fn, rtp, info);
1479                         return 0;
1480                 }
1481         }
1482         return -ENOENT;
1483 }
1484 
1485 /*
1486  *      Tree traversal function.
1487  *
1488  *      Certainly, it is not interrupt safe.
1489  *      However, it is internally reenterable wrt itself and fib6_add/fib6_del.
1490  *      It means, that we can modify tree during walking
1491  *      and use this function for garbage collection, clone pruning,
1492  *      cleaning tree when a device goes down etc. etc.
1493  *
1494  *      It guarantees that every node will be traversed,
1495  *      and that it will be traversed only once.
1496  *
1497  *      Callback function w->func may return:
1498  *      0 -> continue walking.
1499  *      positive value -> walking is suspended (used by tree dumps,
1500  *      and probably by gc, if it will be split to several slices)
1501  *      negative value -> terminate walking.
1502  *
1503  *      The function itself returns:
1504  *      0   -> walk is complete.
1505  *      >0  -> walk is incomplete (i.e. suspended)
1506  *      <0  -> walk is terminated by an error.
1507  */
1508 
1509 static int fib6_walk_continue(struct fib6_walker *w)
1510 {
1511         struct fib6_node *fn, *pn;
1512 
1513         for (;;) {
1514                 fn = w->node;
1515                 if (!fn)
1516                         return 0;
1517 
1518                 if (w->prune && fn != w->root &&
1519                     fn->fn_flags & RTN_RTINFO && w->state < FWS_C) {
1520                         w->state = FWS_C;
1521                         w->leaf = fn->leaf;
1522                 }
1523                 switch (w->state) {
1524 #ifdef CONFIG_IPV6_SUBTREES
1525                 case FWS_S:
1526                         if (FIB6_SUBTREE(fn)) {
1527                                 w->node = FIB6_SUBTREE(fn);
1528                                 continue;
1529                         }
1530                         w->state = FWS_L;
1531 #endif
1532                 case FWS_L:
1533                         if (fn->left) {
1534                                 w->node = fn->left;
1535                                 w->state = FWS_INIT;
1536                                 continue;
1537                         }
1538                         w->state = FWS_R;
1539                 case FWS_R:
1540                         if (fn->right) {
1541                                 w->node = fn->right;
1542                                 w->state = FWS_INIT;
1543                                 continue;
1544                         }
1545                         w->state = FWS_C;
1546                         w->leaf = fn->leaf;
1547                 case FWS_C:
1548                         if (w->leaf && fn->fn_flags & RTN_RTINFO) {
1549                                 int err;
1550 
1551                                 if (w->skip) {
1552                                         w->skip--;
1553                                         goto skip;
1554                                 }
1555 
1556                                 err = w->func(w);
1557                                 if (err)
1558                                         return err;
1559 
1560                                 w->count++;
1561                                 continue;
1562                         }
1563 skip:
1564                         w->state = FWS_U;
1565                 case FWS_U:
1566                         if (fn == w->root)
1567                                 return 0;
1568                         pn = fn->parent;
1569                         w->node = pn;
1570 #ifdef CONFIG_IPV6_SUBTREES
1571                         if (FIB6_SUBTREE(pn) == fn) {
1572                                 WARN_ON(!(fn->fn_flags & RTN_ROOT));
1573                                 w->state = FWS_L;
1574                                 continue;
1575                         }
1576 #endif
1577                         if (pn->left == fn) {
1578                                 w->state = FWS_R;
1579                                 continue;
1580                         }
1581                         if (pn->right == fn) {
1582                                 w->state = FWS_C;
1583                                 w->leaf = w->node->leaf;
1584                                 continue;
1585                         }
1586 #if RT6_DEBUG >= 2
1587                         WARN_ON(1);
1588 #endif
1589                 }
1590         }
1591 }
1592 
1593 static int fib6_walk(struct net *net, struct fib6_walker *w)
1594 {
1595         int res;
1596 
1597         w->state = FWS_INIT;
1598         w->node = w->root;
1599 
1600         fib6_walker_link(net, w);
1601         res = fib6_walk_continue(w);
1602         if (res <= 0)
1603                 fib6_walker_unlink(net, w);
1604         return res;
1605 }
1606 
1607 static int fib6_clean_node(struct fib6_walker *w)
1608 {
1609         int res;
1610         struct rt6_info *rt;
1611         struct fib6_cleaner *c = container_of(w, struct fib6_cleaner, w);
1612         struct nl_info info = {
1613                 .nl_net = c->net,
1614         };
1615 
1616         if (c->sernum != FIB6_NO_SERNUM_CHANGE &&
1617             w->node->fn_sernum != c->sernum)
1618                 w->node->fn_sernum = c->sernum;
1619 
1620         if (!c->func) {
1621                 WARN_ON_ONCE(c->sernum == FIB6_NO_SERNUM_CHANGE);
1622                 w->leaf = NULL;
1623                 return 0;
1624         }
1625 
1626         for (rt = w->leaf; rt; rt = rt->dst.rt6_next) {
1627                 res = c->func(rt, c->arg);
1628                 if (res < 0) {
1629                         w->leaf = rt;
1630                         res = fib6_del(rt, &info);
1631                         if (res) {
1632 #if RT6_DEBUG >= 2
1633                                 pr_debug("%s: del failed: rt=%p@%p err=%d\n",
1634                                          __func__, rt, rt->rt6i_node, res);
1635 #endif
1636                                 continue;
1637                         }
1638                         return 0;
1639                 }
1640                 WARN_ON(res != 0);
1641         }
1642         w->leaf = rt;
1643         return 0;
1644 }
1645 
1646 /*
1647  *      Convenient frontend to tree walker.
1648  *
1649  *      func is called on each route.
1650  *              It may return -1 -> delete this route.
1651  *                            0  -> continue walking
1652  *
1653  *      prune==1 -> only immediate children of node (certainly,
1654  *      ignoring pure split nodes) will be scanned.
1655  */
1656 
1657 static void fib6_clean_tree(struct net *net, struct fib6_node *root,
1658                             int (*func)(struct rt6_info *, void *arg),
1659                             bool prune, int sernum, void *arg)
1660 {
1661         struct fib6_cleaner c;
1662 
1663         c.w.root = root;
1664         c.w.func = fib6_clean_node;
1665         c.w.prune = prune;
1666         c.w.count = 0;
1667         c.w.skip = 0;
1668         c.func = func;
1669         c.sernum = sernum;
1670         c.arg = arg;
1671         c.net = net;
1672 
1673         fib6_walk(net, &c.w);
1674 }
1675 
1676 static void __fib6_clean_all(struct net *net,
1677                              int (*func)(struct rt6_info *, void *),
1678                              int sernum, void *arg)
1679 {
1680         struct fib6_table *table;
1681         struct hlist_head *head;
1682         unsigned int h;
1683 
1684         rcu_read_lock();
1685         for (h = 0; h < FIB6_TABLE_HASHSZ; h++) {
1686                 head = &net->ipv6.fib_table_hash[h];
1687                 hlist_for_each_entry_rcu(table, head, tb6_hlist) {
1688                         write_lock_bh(&table->tb6_lock);
1689                         fib6_clean_tree(net, &table->tb6_root,
1690                                         func, false, sernum, arg);
1691                         write_unlock_bh(&table->tb6_lock);
1692                 }
1693         }
1694         rcu_read_unlock();
1695 }
1696 
1697 void fib6_clean_all(struct net *net, int (*func)(struct rt6_info *, void *),
1698                     void *arg)
1699 {
1700         __fib6_clean_all(net, func, FIB6_NO_SERNUM_CHANGE, arg);
1701 }
1702 
1703 static int fib6_prune_clone(struct rt6_info *rt, void *arg)
1704 {
1705         if (rt->rt6i_flags & RTF_CACHE) {
1706                 RT6_TRACE("pruning clone %p\n", rt);
1707                 return -1;
1708         }
1709 
1710         return 0;
1711 }
1712 
1713 static void fib6_prune_clones(struct net *net, struct fib6_node *fn)
1714 {
1715         fib6_clean_tree(net, fn, fib6_prune_clone, true,
1716                         FIB6_NO_SERNUM_CHANGE, NULL);
1717 }
1718 
1719 static void fib6_flush_trees(struct net *net)
1720 {
1721         int new_sernum = fib6_new_sernum(net);
1722 
1723         __fib6_clean_all(net, NULL, new_sernum, NULL);
1724 }
1725 
1726 /*
1727  *      Garbage collection
1728  */
1729 
1730 struct fib6_gc_args
1731 {
1732         int                     timeout;
1733         int                     more;
1734 };
1735 
1736 static int fib6_age(struct rt6_info *rt, void *arg)
1737 {
1738         struct fib6_gc_args *gc_args = arg;
1739         unsigned long now = jiffies;
1740 
1741         /*
1742          *      check addrconf expiration here.
1743          *      Routes are expired even if they are in use.
1744          *
1745          *      Also age clones. Note, that clones are aged out
1746          *      only if they are not in use now.
1747          */
1748 
1749         if (rt->rt6i_flags & RTF_EXPIRES && rt->dst.expires) {
1750                 if (time_after(now, rt->dst.expires)) {
1751                         RT6_TRACE("expiring %p\n", rt);
1752                         return -1;
1753                 }
1754                 gc_args->more++;
1755         } else if (rt->rt6i_flags & RTF_CACHE) {
1756                 if (atomic_read(&rt->dst.__refcnt) == 0 &&
1757                     time_after_eq(now, rt->dst.lastuse + gc_args->timeout)) {
1758                         RT6_TRACE("aging clone %p\n", rt);
1759                         return -1;
1760                 } else if (rt->rt6i_flags & RTF_GATEWAY) {
1761                         struct neighbour *neigh;
1762                         __u8 neigh_flags = 0;
1763 
1764                         neigh = dst_neigh_lookup(&rt->dst, &rt->rt6i_gateway);
1765                         if (neigh) {
1766                                 neigh_flags = neigh->flags;
1767                                 neigh_release(neigh);
1768                         }
1769                         if (!(neigh_flags & NTF_ROUTER)) {
1770                                 RT6_TRACE("purging route %p via non-router but gateway\n",
1771                                           rt);
1772                                 return -1;
1773                         }
1774                 }
1775                 gc_args->more++;
1776         }
1777 
1778         return 0;
1779 }
1780 
1781 void fib6_run_gc(unsigned long expires, struct net *net, bool force)
1782 {
1783         struct fib6_gc_args gc_args;
1784         unsigned long now;
1785 
1786         if (force) {
1787                 spin_lock_bh(&net->ipv6.fib6_gc_lock);
1788         } else if (!spin_trylock_bh(&net->ipv6.fib6_gc_lock)) {
1789                 mod_timer(&net->ipv6.ip6_fib_timer, jiffies + HZ);
1790                 return;
1791         }
1792         gc_args.timeout = expires ? (int)expires :
1793                           net->ipv6.sysctl.ip6_rt_gc_interval;
1794 
1795         gc_args.more = icmp6_dst_gc();
1796 
1797         fib6_clean_all(net, fib6_age, &gc_args);
1798         now = jiffies;
1799         net->ipv6.ip6_rt_last_gc = now;
1800 
1801         if (gc_args.more)
1802                 mod_timer(&net->ipv6.ip6_fib_timer,
1803                           round_jiffies(now
1804                                         + net->ipv6.sysctl.ip6_rt_gc_interval));
1805         else
1806                 del_timer(&net->ipv6.ip6_fib_timer);
1807         spin_unlock_bh(&net->ipv6.fib6_gc_lock);
1808 }
1809 
1810 static void fib6_gc_timer_cb(unsigned long arg)
1811 {
1812         fib6_run_gc(0, (struct net *)arg, true);
1813 }
1814 
1815 static int __net_init fib6_net_init(struct net *net)
1816 {
1817         size_t size = sizeof(struct hlist_head) * FIB6_TABLE_HASHSZ;
1818 
1819         spin_lock_init(&net->ipv6.fib6_gc_lock);
1820         rwlock_init(&net->ipv6.fib6_walker_lock);
1821         INIT_LIST_HEAD(&net->ipv6.fib6_walkers);
1822         setup_timer(&net->ipv6.ip6_fib_timer, fib6_gc_timer_cb, (unsigned long)net);
1823 
1824         net->ipv6.rt6_stats = kzalloc(sizeof(*net->ipv6.rt6_stats), GFP_KERNEL);
1825         if (!net->ipv6.rt6_stats)
1826                 goto out_timer;
1827 
1828         /* Avoid false sharing : Use at least a full cache line */
1829         size = max_t(size_t, size, L1_CACHE_BYTES);
1830 
1831         net->ipv6.fib_table_hash = kzalloc(size, GFP_KERNEL);
1832         if (!net->ipv6.fib_table_hash)
1833                 goto out_rt6_stats;
1834 
1835         net->ipv6.fib6_main_tbl = kzalloc(sizeof(*net->ipv6.fib6_main_tbl),
1836                                           GFP_KERNEL);
1837         if (!net->ipv6.fib6_main_tbl)
1838                 goto out_fib_table_hash;
1839 
1840         net->ipv6.fib6_main_tbl->tb6_id = RT6_TABLE_MAIN;
1841         net->ipv6.fib6_main_tbl->tb6_root.leaf = net->ipv6.ip6_null_entry;
1842         net->ipv6.fib6_main_tbl->tb6_root.fn_flags =
1843                 RTN_ROOT | RTN_TL_ROOT | RTN_RTINFO;
1844         inet_peer_base_init(&net->ipv6.fib6_main_tbl->tb6_peers);
1845 
1846 #ifdef CONFIG_IPV6_MULTIPLE_TABLES
1847         net->ipv6.fib6_local_tbl = kzalloc(sizeof(*net->ipv6.fib6_local_tbl),
1848                                            GFP_KERNEL);
1849         if (!net->ipv6.fib6_local_tbl)
1850                 goto out_fib6_main_tbl;
1851         net->ipv6.fib6_local_tbl->tb6_id = RT6_TABLE_LOCAL;
1852         net->ipv6.fib6_local_tbl->tb6_root.leaf = net->ipv6.ip6_null_entry;
1853         net->ipv6.fib6_local_tbl->tb6_root.fn_flags =
1854                 RTN_ROOT | RTN_TL_ROOT | RTN_RTINFO;
1855         inet_peer_base_init(&net->ipv6.fib6_local_tbl->tb6_peers);
1856 #endif
1857         fib6_tables_init(net);
1858 
1859         return 0;
1860 
1861 #ifdef CONFIG_IPV6_MULTIPLE_TABLES
1862 out_fib6_main_tbl:
1863         kfree(net->ipv6.fib6_main_tbl);
1864 #endif
1865 out_fib_table_hash:
1866         kfree(net->ipv6.fib_table_hash);
1867 out_rt6_stats:
1868         kfree(net->ipv6.rt6_stats);
1869 out_timer:
1870         return -ENOMEM;
1871 }
1872 
1873 static void fib6_net_exit(struct net *net)
1874 {
1875         rt6_ifdown(net, NULL);
1876         del_timer_sync(&net->ipv6.ip6_fib_timer);
1877 
1878 #ifdef CONFIG_IPV6_MULTIPLE_TABLES
1879         inetpeer_invalidate_tree(&net->ipv6.fib6_local_tbl->tb6_peers);
1880         kfree(net->ipv6.fib6_local_tbl);
1881 #endif
1882         inetpeer_invalidate_tree(&net->ipv6.fib6_main_tbl->tb6_peers);
1883         kfree(net->ipv6.fib6_main_tbl);
1884         kfree(net->ipv6.fib_table_hash);
1885         kfree(net->ipv6.rt6_stats);
1886 }
1887 
1888 static struct pernet_operations fib6_net_ops = {
1889         .init = fib6_net_init,
1890         .exit = fib6_net_exit,
1891 };
1892 
1893 int __init fib6_init(void)
1894 {
1895         int ret = -ENOMEM;
1896 
1897         fib6_node_kmem = kmem_cache_create("fib6_nodes",
1898                                            sizeof(struct fib6_node),
1899                                            0, SLAB_HWCACHE_ALIGN,
1900                                            NULL);
1901         if (!fib6_node_kmem)
1902                 goto out;
1903 
1904         ret = register_pernet_subsys(&fib6_net_ops);
1905         if (ret)
1906                 goto out_kmem_cache_create;
1907 
1908         ret = __rtnl_register(PF_INET6, RTM_GETROUTE, NULL, inet6_dump_fib,
1909                               NULL);
1910         if (ret)
1911                 goto out_unregister_subsys;
1912 
1913         __fib6_flush_trees = fib6_flush_trees;
1914 out:
1915         return ret;
1916 
1917 out_unregister_subsys:
1918         unregister_pernet_subsys(&fib6_net_ops);
1919 out_kmem_cache_create:
1920         kmem_cache_destroy(fib6_node_kmem);
1921         goto out;
1922 }
1923 
1924 void fib6_gc_cleanup(void)
1925 {
1926         unregister_pernet_subsys(&fib6_net_ops);
1927         kmem_cache_destroy(fib6_node_kmem);
1928 }
1929 
1930 #ifdef CONFIG_PROC_FS
1931 
1932 struct ipv6_route_iter {
1933         struct seq_net_private p;
1934         struct fib6_walker w;
1935         loff_t skip;
1936         struct fib6_table *tbl;
1937         int sernum;
1938 };
1939 
1940 static int ipv6_route_seq_show(struct seq_file *seq, void *v)
1941 {
1942         struct rt6_info *rt = v;
1943         struct ipv6_route_iter *iter = seq->private;
1944 
1945         seq_printf(seq, "%pi6 %02x ", &rt->rt6i_dst.addr, rt->rt6i_dst.plen);
1946 
1947 #ifdef CONFIG_IPV6_SUBTREES
1948         seq_printf(seq, "%pi6 %02x ", &rt->rt6i_src.addr, rt->rt6i_src.plen);
1949 #else
1950         seq_puts(seq, "00000000000000000000000000000000 00 ");
1951 #endif
1952         if (rt->rt6i_flags & RTF_GATEWAY)
1953                 seq_printf(seq, "%pi6", &rt->rt6i_gateway);
1954         else
1955                 seq_puts(seq, "00000000000000000000000000000000");
1956 
1957         seq_printf(seq, " %08x %08x %08x %08x %8s\n",
1958                    rt->rt6i_metric, atomic_read(&rt->dst.__refcnt),
1959                    rt->dst.__use, rt->rt6i_flags,
1960                    rt->dst.dev ? rt->dst.dev->name : "");
1961         iter->w.leaf = NULL;
1962         return 0;
1963 }
1964 
1965 static int ipv6_route_yield(struct fib6_walker *w)
1966 {
1967         struct ipv6_route_iter *iter = w->args;
1968 
1969         if (!iter->skip)
1970                 return 1;
1971 
1972         do {
1973                 iter->w.leaf = iter->w.leaf->dst.rt6_next;
1974                 iter->skip--;
1975                 if (!iter->skip && iter->w.leaf)
1976                         return 1;
1977         } while (iter->w.leaf);
1978 
1979         return 0;
1980 }
1981 
1982 static void ipv6_route_seq_setup_walk(struct ipv6_route_iter *iter,
1983                                       struct net *net)
1984 {
1985         memset(&iter->w, 0, sizeof(iter->w));
1986         iter->w.func = ipv6_route_yield;
1987         iter->w.root = &iter->tbl->tb6_root;
1988         iter->w.state = FWS_INIT;
1989         iter->w.node = iter->w.root;
1990         iter->w.args = iter;
1991         iter->sernum = iter->w.root->fn_sernum;
1992         INIT_LIST_HEAD(&iter->w.lh);
1993         fib6_walker_link(net, &iter->w);
1994 }
1995 
1996 static struct fib6_table *ipv6_route_seq_next_table(struct fib6_table *tbl,
1997                                                     struct net *net)
1998 {
1999         unsigned int h;
2000         struct hlist_node *node;
2001 
2002         if (tbl) {
2003                 h = (tbl->tb6_id & (FIB6_TABLE_HASHSZ - 1)) + 1;
2004                 node = rcu_dereference_bh(hlist_next_rcu(&tbl->tb6_hlist));
2005         } else {
2006                 h = 0;
2007                 node = NULL;
2008         }
2009 
2010         while (!node && h < FIB6_TABLE_HASHSZ) {
2011                 node = rcu_dereference_bh(
2012                         hlist_first_rcu(&net->ipv6.fib_table_hash[h++]));
2013         }
2014         return hlist_entry_safe(node, struct fib6_table, tb6_hlist);
2015 }
2016 
2017 static void ipv6_route_check_sernum(struct ipv6_route_iter *iter)
2018 {
2019         if (iter->sernum != iter->w.root->fn_sernum) {
2020                 iter->sernum = iter->w.root->fn_sernum;
2021                 iter->w.state = FWS_INIT;
2022                 iter->w.node = iter->w.root;
2023                 WARN_ON(iter->w.skip);
2024                 iter->w.skip = iter->w.count;
2025         }
2026 }
2027 
2028 static void *ipv6_route_seq_next(struct seq_file *seq, void *v, loff_t *pos)
2029 {
2030         int r;
2031         struct rt6_info *n;
2032         struct net *net = seq_file_net(seq);
2033         struct ipv6_route_iter *iter = seq->private;
2034 
2035         if (!v)
2036                 goto iter_table;
2037 
2038         n = ((struct rt6_info *)v)->dst.rt6_next;
2039         if (n) {
2040                 ++*pos;
2041                 return n;
2042         }
2043 
2044 iter_table:
2045         ipv6_route_check_sernum(iter);
2046         read_lock(&iter->tbl->tb6_lock);
2047         r = fib6_walk_continue(&iter->w);
2048         read_unlock(&iter->tbl->tb6_lock);
2049         if (r > 0) {
2050                 if (v)
2051                         ++*pos;
2052                 return iter->w.leaf;
2053         } else if (r < 0) {
2054                 fib6_walker_unlink(net, &iter->w);
2055                 return NULL;
2056         }
2057         fib6_walker_unlink(net, &iter->w);
2058 
2059         iter->tbl = ipv6_route_seq_next_table(iter->tbl, net);
2060         if (!iter->tbl)
2061                 return NULL;
2062 
2063         ipv6_route_seq_setup_walk(iter, net);
2064         goto iter_table;
2065 }
2066 
2067 static void *ipv6_route_seq_start(struct seq_file *seq, loff_t *pos)
2068         __acquires(RCU_BH)
2069 {
2070         struct net *net = seq_file_net(seq);
2071         struct ipv6_route_iter *iter = seq->private;
2072 
2073         rcu_read_lock_bh();
2074         iter->tbl = ipv6_route_seq_next_table(NULL, net);
2075         iter->skip = *pos;
2076 
2077         if (iter->tbl) {
2078                 ipv6_route_seq_setup_walk(iter, net);
2079                 return ipv6_route_seq_next(seq, NULL, pos);
2080         } else {
2081                 return NULL;
2082         }
2083 }
2084 
2085 static bool ipv6_route_iter_active(struct ipv6_route_iter *iter)
2086 {
2087         struct fib6_walker *w = &iter->w;
2088         return w->node && !(w->state == FWS_U && w->node == w->root);
2089 }
2090 
2091 static void ipv6_route_seq_stop(struct seq_file *seq, void *v)
2092         __releases(RCU_BH)
2093 {
2094         struct net *net = seq_file_net(seq);
2095         struct ipv6_route_iter *iter = seq->private;
2096 
2097         if (ipv6_route_iter_active(iter))
2098                 fib6_walker_unlink(net, &iter->w);
2099 
2100         rcu_read_unlock_bh();
2101 }
2102 
2103 static const struct seq_operations ipv6_route_seq_ops = {
2104         .start  = ipv6_route_seq_start,
2105         .next   = ipv6_route_seq_next,
2106         .stop   = ipv6_route_seq_stop,
2107         .show   = ipv6_route_seq_show
2108 };
2109 
2110 int ipv6_route_open(struct inode *inode, struct file *file)
2111 {
2112         return seq_open_net(inode, file, &ipv6_route_seq_ops,
2113                             sizeof(struct ipv6_route_iter));
2114 }
2115 
2116 #endif /* CONFIG_PROC_FS */
2117 

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