net/ipv6/ip6_fib.c

   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         u16 nlflags = NLM_F_EXCL;
 747         int err;
 748
 749         if (info->nlh && (info->nlh->nlmsg_flags & NLM_F_APPEND))
 750                 nlflags |= NLM_F_APPEND;
 751
 752         ins = &fn->leaf;
 753
 754         for (iter = fn->leaf; iter; iter = iter->dst.rt6_next) {
 755                 /*
 756                  *      Search for duplicates
 757                  */
 758
 759                 if (iter->rt6i_metric == rt->rt6i_metric) {
 760                         /*
 761                          *      Same priority level
 762                          */
 763                         if (info->nlh &&
 764                             (info->nlh->nlmsg_flags & NLM_F_EXCL))
 765                                 return -EEXIST;
 766
 767                         nlflags &= ~NLM_F_EXCL;
 768                         if (replace) {
 769                                 if (rt_can_ecmp == rt6_qualify_for_ecmp(iter)) {
 770                                         found++;
 771                                         break;
 772                                 }
 773                                 if (rt_can_ecmp)
 774                                         fallback_ins = fallback_ins ?: ins;
 775                                 goto next_iter;
 776                         }
 777
 778                         if (iter->dst.dev == rt->dst.dev &&
 779                             iter->rt6i_idev == rt->rt6i_idev &&
 780                             ipv6_addr_equal(&iter->rt6i_gateway,
 781                                             &rt->rt6i_gateway)) {
 782                                 if (rt->rt6i_nsiblings)
 783                                         rt->rt6i_nsiblings = 0;
 784                                 if (!(iter->rt6i_flags & RTF_EXPIRES))
 785                                         return -EEXIST;
 786                                 if (!(rt->rt6i_flags & RTF_EXPIRES))
 787                                         rt6_clean_expires(iter);
 788                                 else
 789                                         rt6_set_expires(iter, rt->dst.expires);
 790                                 iter->rt6i_pmtu = rt->rt6i_pmtu;
 791                                 return -EEXIST;
 792                         }
 793                         /* If we have the same destination and the same metric,
 794                          * but not the same gateway, then the route we try to
 795                          * add is sibling to this route, increment our counter
 796                          * of siblings, and later we will add our route to the
 797                          * list.
 798                          * Only static routes (which don't have flag
 799                          * RTF_EXPIRES) are used for ECMPv6.
 800                          *
 801                          * To avoid long list, we only had siblings if the
 802                          * route have a gateway.
 803                          */
 804                         if (rt_can_ecmp &&
 805                             rt6_qualify_for_ecmp(iter))
 806                                 rt->rt6i_nsiblings++;
 807                 }
 808
 809                 if (iter->rt6i_metric > rt->rt6i_metric)
 810                         break;
 811
 812 next_iter:
 813                 ins = &iter->dst.rt6_next;
 814         }
 815
 816         if (fallback_ins && !found) {
 817                 /* No ECMP-able route found, replace first non-ECMP one */
 818                 ins = fallback_ins;
 819                 iter = *ins;
 820                 found++;
 821         }
 822
 823         /* Reset round-robin state, if necessary */
 824         if (ins == &fn->leaf)
 825                 fn->rr_ptr = NULL;
 826
 827         /* Link this route to others same route. */
 828         if (rt->rt6i_nsiblings) {
 829                 unsigned int rt6i_nsiblings;
 830                 struct rt6_info *sibling, *temp_sibling;
 831
 832                 /* Find the first route that have the same metric */
 833                 sibling = fn->leaf;
 834                 while (sibling) {
 835                         if (sibling->rt6i_metric == rt->rt6i_metric &&
 836                             rt6_qualify_for_ecmp(sibling)) {
 837                                 list_add_tail(&rt->rt6i_siblings,
 838                                               &sibling->rt6i_siblings);
 839                                 break;
 840                         }
 841                         sibling = sibling->dst.rt6_next;
 842                 }
 843                 /* For each sibling in the list, increment the counter of
 844                  * siblings. BUG() if counters does not match, list of siblings
 845                  * is broken!
 846                  */
 847                 rt6i_nsiblings = 0;
 848                 list_for_each_entry_safe(sibling, temp_sibling,
 849                                          &rt->rt6i_siblings, rt6i_siblings) {
 850                         sibling->rt6i_nsiblings++;
 851                         BUG_ON(sibling->rt6i_nsiblings != rt->rt6i_nsiblings);
 852                         rt6i_nsiblings++;
 853                 }
 854                 BUG_ON(rt6i_nsiblings != rt->rt6i_nsiblings);
 855         }
 856
 857         /*
 858          *      insert node
 859          */
 860         if (!replace) {
 861                 if (!add)
 862                         pr_warn("NLM_F_CREATE should be set when creating new route\n");
 863
 864 add:
 865                 nlflags |= NLM_F_CREATE;
 866                 err = fib6_commit_metrics(&rt->dst, mxc);
 867                 if (err)
 868                         return err;
 869
 870                 rt->dst.rt6_next = iter;
 871                 *ins = rt;
 872                 rt->rt6i_node = fn;
 873                 atomic_inc(&rt->rt6i_ref);
 874                 inet6_rt_notify(RTM_NEWROUTE, rt, info, nlflags);
 875                 info->nl_net->ipv6.rt6_stats->fib_rt_entries++;
 876
 877                 if (!(fn->fn_flags & RTN_RTINFO)) {
 878                         info->nl_net->ipv6.rt6_stats->fib_route_nodes++;
 879                         fn->fn_flags |= RTN_RTINFO;
 880                 }
 881
 882         } else {
 883                 int nsiblings;
 884
 885                 if (!found) {
 886                         if (add)
 887                                 goto add;
 888                         pr_warn("NLM_F_REPLACE set, but no existing node found!\n");
 889                         return -ENOENT;
 890                 }
 891
 892                 err = fib6_commit_metrics(&rt->dst, mxc);
 893                 if (err)
 894                         return err;
 895
 896                 *ins = rt;
 897                 rt->rt6i_node = fn;
 898                 rt->dst.rt6_next = iter->dst.rt6_next;
 899                 atomic_inc(&rt->rt6i_ref);
 900                 inet6_rt_notify(RTM_NEWROUTE, rt, info, NLM_F_REPLACE);
 901                 if (!(fn->fn_flags & RTN_RTINFO)) {
 902                         info->nl_net->ipv6.rt6_stats->fib_route_nodes++;
 903                         fn->fn_flags |= RTN_RTINFO;
 904                 }
 905                 nsiblings = iter->rt6i_nsiblings;
 906                 fib6_purge_rt(iter, fn, info->nl_net);
 907                 rt6_release(iter);
 908
 909                 if (nsiblings) {
 910                         /* Replacing an ECMP route, remove all siblings */
 911                         ins = &rt->dst.rt6_next;
 912                         iter = *ins;
 913                         while (iter) {
 914                                 if (rt6_qualify_for_ecmp(iter)) {
 915                                         *ins = iter->dst.rt6_next;
 916                                         fib6_purge_rt(iter, fn, info->nl_net);
 917                                         rt6_release(iter);
 918                                         nsiblings--;
 919                                 } else {
 920                                         ins = &iter->dst.rt6_next;
 921                                 }
 922                                 iter = *ins;
 923                         }
 924                         WARN_ON(nsiblings != 0);
 925                 }
 926         }
 927
 928         return 0;
 929 }
 930
 931 static void fib6_start_gc(struct net *net, struct rt6_info *rt)
 932 {
 933         if (!timer_pending(&net->ipv6.ip6_fib_timer) &&
 934             (rt->rt6i_flags & (RTF_EXPIRES | RTF_CACHE)))
 935                 mod_timer(&net->ipv6.ip6_fib_timer,
 936                           jiffies + net->ipv6.sysctl.ip6_rt_gc_interval);
 937 }
 938
 939 void fib6_force_start_gc(struct net *net)
 940 {
 941         if (!timer_pending(&net->ipv6.ip6_fib_timer))
 942                 mod_timer(&net->ipv6.ip6_fib_timer,
 943                           jiffies + net->ipv6.sysctl.ip6_rt_gc_interval);
 944 }
 945
 946 /*
 947  *      Add routing information to the routing tree.
 948  *      <destination addr>/<source addr>
 949  *      with source addr info in sub-trees
 950  */
 951
 952 int fib6_add(struct fib6_node *root, struct rt6_info *rt,
 953              struct nl_info *info, struct mx6_config *mxc)
 954 {
 955         struct fib6_node *fn, *pn = NULL;
 956         int err = -ENOMEM;
 957         int allow_create = 1;
 958         int replace_required = 0;
 959         int sernum = fib6_new_sernum(info->nl_net);
 960
 961         if (WARN_ON_ONCE((rt->dst.flags & DST_NOCACHE) &&
 962                          !atomic_read(&rt->dst.__refcnt)))
 963                 return -EINVAL;
 964
 965         if (info->nlh) {
 966                 if (!(info->nlh->nlmsg_flags & NLM_F_CREATE))
 967                         allow_create = 0;
 968                 if (info->nlh->nlmsg_flags & NLM_F_REPLACE)
 969                         replace_required = 1;
 970         }
 971         if (!allow_create && !replace_required)
 972                 pr_warn("RTM_NEWROUTE with no NLM_F_CREATE or NLM_F_REPLACE\n");
 973
 974         fn = fib6_add_1(root, &rt->rt6i_dst.addr, rt->rt6i_dst.plen,
 975                         offsetof(struct rt6_info, rt6i_dst), allow_create,
 976                         replace_required, sernum);
 977         if (IS_ERR(fn)) {
 978                 err = PTR_ERR(fn);
 979                 fn = NULL;
 980                 goto out;
 981         }
 982
 983         pn = fn;
 984
 985 #ifdef CONFIG_IPV6_SUBTREES
 986         if (rt->rt6i_src.plen) {
 987                 struct fib6_node *sn;
 988
 989                 if (!fn->subtree) {
 990                         struct fib6_node *sfn;
 991
 992                         /*
 993                          * Create subtree.
 994                          *
 995                          *              fn[main tree]
 996                          *              |
 997                          *              sfn[subtree root]
 998                          *                 \
 999                          *                  sn[new leaf node]
1000                          */
1001
1002                         /* Create subtree root node */
1003                         sfn = node_alloc();
1004                         if (!sfn)
1005                                 goto st_failure;
1006
1007                         sfn->leaf = info->nl_net->ipv6.ip6_null_entry;
1008                         atomic_inc(&info->nl_net->ipv6.ip6_null_entry->rt6i_ref);
1009                         sfn->fn_flags = RTN_ROOT;
1010                         sfn->fn_sernum = sernum;
1011
1012                         /* Now add the first leaf node to new subtree */
1013
1014                         sn = fib6_add_1(sfn, &rt->rt6i_src.addr,
1015                                         rt->rt6i_src.plen,
1016                                         offsetof(struct rt6_info, rt6i_src),
1017                                         allow_create, replace_required, sernum);
1018
1019                         if (IS_ERR(sn)) {
1020                                 /* If it is failed, discard just allocated
1021                                    root, and then (in st_failure) stale node
1022                                    in main tree.
1023                                  */
1024                                 node_free(sfn);
1025                                 err = PTR_ERR(sn);
1026                                 goto st_failure;
1027                         }
1028
1029                         /* Now link new subtree to main tree */
1030                         sfn->parent = fn;
1031                         fn->subtree = sfn;
1032                 } else {
1033                         sn = fib6_add_1(fn->subtree, &rt->rt6i_src.addr,
1034                                         rt->rt6i_src.plen,
1035                                         offsetof(struct rt6_info, rt6i_src),
1036                                         allow_create, replace_required, sernum);
1037
1038                         if (IS_ERR(sn)) {
1039                                 err = PTR_ERR(sn);
1040                                 goto st_failure;
1041                         }
1042                 }
1043
1044                 if (!fn->leaf) {
1045                         fn->leaf = rt;
1046                         atomic_inc(&rt->rt6i_ref);
1047                 }
1048                 fn = sn;
1049         }
1050 #endif
1051
1052         err = fib6_add_rt2node(fn, rt, info, mxc);
1053         if (!err) {
1054                 fib6_start_gc(info->nl_net, rt);
1055                 if (!(rt->rt6i_flags & RTF_CACHE))
1056                         fib6_prune_clones(info->nl_net, pn);
1057                 rt->dst.flags &= ~DST_NOCACHE;
1058         }
1059
1060 out:
1061         if (err) {
1062 #ifdef CONFIG_IPV6_SUBTREES
1063                 /*
1064                  * If fib6_add_1 has cleared the old leaf pointer in the
1065                  * super-tree leaf node we have to find a new one for it.
1066                  */
1067                 if (pn != fn && pn->leaf == rt) {
1068                         pn->leaf = NULL;
1069                         atomic_dec(&rt->rt6i_ref);
1070                 }
1071                 if (pn != fn && !pn->leaf && !(pn->fn_flags & RTN_RTINFO)) {
1072                         pn->leaf = fib6_find_prefix(info->nl_net, pn);
1073 #if RT6_DEBUG >= 2
1074                         if (!pn->leaf) {
1075                                 WARN_ON(pn->leaf == NULL);
1076                                 pn->leaf = info->nl_net->ipv6.ip6_null_entry;
1077                         }
1078 #endif
1079                         atomic_inc(&pn->leaf->rt6i_ref);
1080                 }
1081 #endif
1082                 if (!(rt->dst.flags & DST_NOCACHE))
1083                         dst_free(&rt->dst);
1084         }
1085         return err;
1086
1087 #ifdef CONFIG_IPV6_SUBTREES
1088         /* Subtree creation failed, probably main tree node
1089            is orphan. If it is, shoot it.
1090          */
1091 st_failure:
1092         if (fn && !(fn->fn_flags & (RTN_RTINFO|RTN_ROOT)))
1093                 fib6_repair_tree(info->nl_net, fn);
1094         if (!(rt->dst.flags & DST_NOCACHE))
1095                 dst_free(&rt->dst);
1096         return err;
1097 #endif
1098 }
1099
1100 /*
1101  *      Routing tree lookup
1102  *
1103  */
1104
1105 struct lookup_args {
1106         int                     offset;         /* key offset on rt6_info       */
1107         const struct in6_addr   *addr;          /* search key                   */
1108 };
1109
1110 static struct fib6_node *fib6_lookup_1(struct fib6_node *root,
1111                                        struct lookup_args *args)
1112 {
1113         struct fib6_node *fn;
1114         __be32 dir;
1115
1116         if (unlikely(args->offset == 0))
1117                 return NULL;
1118
1119         /*
1120          *      Descend on a tree
1121          */
1122
1123         fn = root;
1124
1125         for (;;) {
1126                 struct fib6_node *next;
1127
1128                 dir = addr_bit_set(args->addr, fn->fn_bit);
1129
1130                 next = dir ? fn->right : fn->left;
1131
1132                 if (next) {
1133                         fn = next;
1134                         continue;
1135                 }
1136                 break;
1137         }
1138
1139         while (fn) {
1140                 if (FIB6_SUBTREE(fn) || fn->fn_flags & RTN_RTINFO) {
1141                         struct rt6key *key;
1142
1143                         key = (struct rt6key *) ((u8 *) fn->leaf +
1144                                                  args->offset);
1145
1146                         if (ipv6_prefix_equal(&key->addr, args->addr, key->plen)) {
1147 #ifdef CONFIG_IPV6_SUBTREES
1148                                 if (fn->subtree) {
1149                                         struct fib6_node *sfn;
1150                                         sfn = fib6_lookup_1(fn->subtree,
1151                                                             args + 1);
1152                                         if (!sfn)
1153                                                 goto backtrack;
1154                                         fn = sfn;
1155                                 }
1156 #endif
1157                                 if (fn->fn_flags & RTN_RTINFO)
1158                                         return fn;
1159                         }
1160                 }
1161 #ifdef CONFIG_IPV6_SUBTREES
1162 backtrack:
1163 #endif
1164                 if (fn->fn_flags & RTN_ROOT)
1165                         break;
1166
1167                 fn = fn->parent;
1168         }
1169
1170         return NULL;
1171 }
1172
1173 struct fib6_node *fib6_lookup(struct fib6_node *root, const struct in6_addr *daddr,
1174                               const struct in6_addr *saddr)
1175 {
1176         struct fib6_node *fn;
1177         struct lookup_args args[] = {
1178                 {
1179                         .offset = offsetof(struct rt6_info, rt6i_dst),
1180                         .addr = daddr,
1181                 },
1182 #ifdef CONFIG_IPV6_SUBTREES
1183                 {
1184                         .offset = offsetof(struct rt6_info, rt6i_src),
1185                         .addr = saddr,
1186                 },
1187 #endif
1188                 {
1189                         .offset = 0,    /* sentinel */
1190                 }
1191         };
1192
1193         fn = fib6_lookup_1(root, daddr ? args : args + 1);
1194         if (!fn || fn->fn_flags & RTN_TL_ROOT)
1195                 fn = root;
1196
1197         return fn;
1198 }
1199
1200 /*
1201  *      Get node with specified destination prefix (and source prefix,
1202  *      if subtrees are used)
1203  */
1204
1205
1206 static struct fib6_node *fib6_locate_1(struct fib6_node *root,
1207                                        const struct in6_addr *addr,
1208                                        int plen, int offset)
1209 {
1210         struct fib6_node *fn;
1211
1212         for (fn = root; fn ; ) {
1213                 struct rt6key *key = (struct rt6key *)((u8 *)fn->leaf + offset);
1214
1215                 /*
1216                  *      Prefix match
1217                  */
1218                 if (plen < fn->fn_bit ||
1219                     !ipv6_prefix_equal(&key->addr, addr, fn->fn_bit))
1220                         return NULL;
1221
1222                 if (plen == fn->fn_bit)
1223                         return fn;
1224
1225                 /*
1226                  *      We have more bits to go
1227                  */
1228                 if (addr_bit_set(addr, fn->fn_bit))
1229                         fn = fn->right;
1230                 else
1231                         fn = fn->left;
1232         }
1233         return NULL;
1234 }
1235
1236 struct fib6_node *fib6_locate(struct fib6_node *root,
1237                               const struct in6_addr *daddr, int dst_len,
1238                               const struct in6_addr *saddr, int src_len)
1239 {
1240         struct fib6_node *fn;
1241
1242         fn = fib6_locate_1(root, daddr, dst_len,
1243                            offsetof(struct rt6_info, rt6i_dst));
1244
1245 #ifdef CONFIG_IPV6_SUBTREES
1246         if (src_len) {
1247                 WARN_ON(saddr == NULL);
1248                 if (fn && fn->subtree)
1249                         fn = fib6_locate_1(fn->subtree, saddr, src_len,
1250                                            offsetof(struct rt6_info, rt6i_src));
1251         }
1252 #endif
1253
1254         if (fn && fn->fn_flags & RTN_RTINFO)
1255                 return fn;
1256
1257         return NULL;
1258 }
1259
1260
1261 /*
1262  *      Deletion
1263  *
1264  */
1265
1266 static struct rt6_info *fib6_find_prefix(struct net *net, struct fib6_node *fn)
1267 {
1268         if (fn->fn_flags & RTN_ROOT)
1269                 return net->ipv6.ip6_null_entry;
1270
1271         while (fn) {
1272                 if (fn->left)
1273                         return fn->left->leaf;
1274                 if (fn->right)
1275                         return fn->right->leaf;
1276
1277                 fn = FIB6_SUBTREE(fn);
1278         }
1279         return NULL;
1280 }
1281
1282 /*
1283  *      Called to trim the tree of intermediate nodes when possible. "fn"
1284  *      is the node we want to try and remove.
1285  */
1286
1287 static struct fib6_node *fib6_repair_tree(struct net *net,
1288                                            struct fib6_node *fn)
1289 {
1290         int children;
1291         int nstate;
1292         struct fib6_node *child, *pn;
1293         struct fib6_walker *w;
1294         int iter = 0;
1295
1296         for (;;) {
1297                 RT6_TRACE("fixing tree: plen=%d iter=%d\n", fn->fn_bit, iter);
1298                 iter++;
1299
1300                 WARN_ON(fn->fn_flags & RTN_RTINFO);
1301                 WARN_ON(fn->fn_flags & RTN_TL_ROOT);
1302                 WARN_ON(fn->leaf);
1303
1304                 children = 0;
1305                 child = NULL;
1306                 if (fn->right)
1307                         child = fn->right, children |= 1;
1308                 if (fn->left)
1309                         child = fn->left, children |= 2;
1310
1311                 if (children == 3 || FIB6_SUBTREE(fn)
1312 #ifdef CONFIG_IPV6_SUBTREES
1313                     /* Subtree root (i.e. fn) may have one child */
1314                     || (children && fn->fn_flags & RTN_ROOT)
1315 #endif
1316                     ) {
1317                         fn->leaf = fib6_find_prefix(net, fn);
1318 #if RT6_DEBUG >= 2
1319                         if (!fn->leaf) {
1320                                 WARN_ON(!fn->leaf);
1321                                 fn->leaf = net->ipv6.ip6_null_entry;
1322                         }
1323 #endif
1324                         atomic_inc(&fn->leaf->rt6i_ref);
1325                         return fn->parent;
1326                 }
1327
1328                 pn = fn->parent;
1329 #ifdef CONFIG_IPV6_SUBTREES
1330                 if (FIB6_SUBTREE(pn) == fn) {
1331                         WARN_ON(!(fn->fn_flags & RTN_ROOT));
1332                         FIB6_SUBTREE(pn) = NULL;
1333                         nstate = FWS_L;
1334                 } else {
1335                         WARN_ON(fn->fn_flags & RTN_ROOT);
1336 #endif
1337                         if (pn->right == fn)
1338                                 pn->right = child;
1339                         else if (pn->left == fn)
1340                                 pn->left = child;
1341 #if RT6_DEBUG >= 2
1342                         else
1343                                 WARN_ON(1);
1344 #endif
1345                         if (child)
1346                                 child->parent = pn;
1347                         nstate = FWS_R;
1348 #ifdef CONFIG_IPV6_SUBTREES
1349                 }
1350 #endif
1351
1352                 read_lock(&net->ipv6.fib6_walker_lock);
1353                 FOR_WALKERS(net, w) {
1354                         if (!child) {
1355                                 if (w->root == fn) {
1356                                         w->root = w->node = NULL;
1357                                         RT6_TRACE("W %p adjusted by delroot 1\n", w);
1358                                 } else if (w->node == fn) {
1359                                         RT6_TRACE("W %p adjusted by delnode 1, s=%d/%d\n", w, w->state, nstate);
1360                                         w->node = pn;
1361                                         w->state = nstate;
1362                                 }
1363                         } else {
1364                                 if (w->root == fn) {
1365                                         w->root = child;
1366                                         RT6_TRACE("W %p adjusted by delroot 2\n", w);
1367                                 }
1368                                 if (w->node == fn) {
1369                                         w->node = child;
1370                                         if (children&2) {
1371                                                 RT6_TRACE("W %p adjusted by delnode 2, s=%d\n", w, w->state);
1372                                                 w->state = w->state >= FWS_R ? FWS_U : FWS_INIT;
1373                                         } else {
1374                                                 RT6_TRACE("W %p adjusted by delnode 2, s=%d\n", w, w->state);
1375                                                 w->state = w->state >= FWS_C ? FWS_U : FWS_INIT;
1376                                         }
1377                                 }
1378                         }
1379                 }
1380                 read_unlock(&net->ipv6.fib6_walker_lock);
1381
1382                 node_free(fn);
1383                 if (pn->fn_flags & RTN_RTINFO || FIB6_SUBTREE(pn))
1384                         return pn;
1385
1386                 rt6_release(pn->leaf);
1387                 pn->leaf = NULL;
1388                 fn = pn;
1389         }
1390 }
1391
1392 static void fib6_del_route(struct fib6_node *fn, struct rt6_info **rtp,
1393                            struct nl_info *info)
1394 {
1395         struct fib6_walker *w;
1396         struct rt6_info *rt = *rtp;
1397         struct net *net = info->nl_net;
1398
1399         RT6_TRACE("fib6_del_route\n");
1400
1401         /* Unlink it */
1402         *rtp = rt->dst.rt6_next;
1403         rt->rt6i_node = NULL;
1404         net->ipv6.rt6_stats->fib_rt_entries--;
1405         net->ipv6.rt6_stats->fib_discarded_routes++;
1406
1407         /* Reset round-robin state, if necessary */
1408         if (fn->rr_ptr == rt)
1409                 fn->rr_ptr = NULL;
1410
1411         /* Remove this entry from other siblings */
1412         if (rt->rt6i_nsiblings) {
1413                 struct rt6_info *sibling, *next_sibling;
1414
1415                 list_for_each_entry_safe(sibling, next_sibling,
1416                                          &rt->rt6i_siblings, rt6i_siblings)
1417                         sibling->rt6i_nsiblings--;
1418                 rt->rt6i_nsiblings = 0;
1419                 list_del_init(&rt->rt6i_siblings);
1420         }
1421
1422         /* Adjust walkers */
1423         read_lock(&net->ipv6.fib6_walker_lock);
1424         FOR_WALKERS(net, w) {
1425                 if (w->state == FWS_C && w->leaf == rt) {
1426                         RT6_TRACE("walker %p adjusted by delroute\n", w);
1427                         w->leaf = rt->dst.rt6_next;
1428                         if (!w->leaf)
1429                                 w->state = FWS_U;
1430                 }
1431         }
1432         read_unlock(&net->ipv6.fib6_walker_lock);
1433
1434         rt->dst.rt6_next = NULL;
1435
1436         /* If it was last route, expunge its radix tree node */
1437         if (!fn->leaf) {
1438                 fn->fn_flags &= ~RTN_RTINFO;
1439                 net->ipv6.rt6_stats->fib_route_nodes--;
1440                 fn = fib6_repair_tree(net, fn);
1441         }
1442
1443         fib6_purge_rt(rt, fn, net);
1444
1445         inet6_rt_notify(RTM_DELROUTE, rt, info, 0);
1446         rt6_release(rt);
1447 }
1448
1449 int fib6_del(struct rt6_info *rt, struct nl_info *info)
1450 {
1451         struct net *net = info->nl_net;
1452         struct fib6_node *fn = rt->rt6i_node;
1453         struct rt6_info **rtp;
1454
1455 #if RT6_DEBUG >= 2
1456         if (rt->dst.obsolete > 0) {
1457                 WARN_ON(fn);
1458                 return -ENOENT;
1459         }
1460 #endif
1461         if (!fn || rt == net->ipv6.ip6_null_entry)
1462                 return -ENOENT;
1463
1464         WARN_ON(!(fn->fn_flags & RTN_RTINFO));
1465
1466         if (!(rt->rt6i_flags & RTF_CACHE)) {
1467                 struct fib6_node *pn = fn;
1468 #ifdef CONFIG_IPV6_SUBTREES
1469                 /* clones of this route might be in another subtree */
1470                 if (rt->rt6i_src.plen) {
1471                         while (!(pn->fn_flags & RTN_ROOT))
1472                                 pn = pn->parent;
1473                         pn = pn->parent;
1474                 }
1475 #endif
1476                 fib6_prune_clones(info->nl_net, pn);
1477         }
1478
1479         /*
1480          *      Walk the leaf entries looking for ourself
1481          */
1482
1483         for (rtp = &fn->leaf; *rtp; rtp = &(*rtp)->dst.rt6_next) {
1484                 if (*rtp == rt) {
1485                         fib6_del_route(fn, rtp, info);
1486                         return 0;
1487                 }
1488         }
1489         return -ENOENT;
1490 }
1491
1492 /*
1493  *      Tree traversal function.
1494  *
1495  *      Certainly, it is not interrupt safe.
1496  *      However, it is internally reenterable wrt itself and fib6_add/fib6_del.
1497  *      It means, that we can modify tree during walking
1498  *      and use this function for garbage collection, clone pruning,
1499  *      cleaning tree when a device goes down etc. etc.
1500  *
1501  *      It guarantees that every node will be traversed,
1502  *      and that it will be traversed only once.
1503  *
1504  *      Callback function w->func may return:
1505  *      0 -> continue walking.
1506  *      positive value -> walking is suspended (used by tree dumps,
1507  *      and probably by gc, if it will be split to several slices)
1508  *      negative value -> terminate walking.
1509  *
1510  *      The function itself returns:
1511  *      0   -> walk is complete.
1512  *      >0  -> walk is incomplete (i.e. suspended)
1513  *      <0  -> walk is terminated by an error.
1514  */
1515
1516 static int fib6_walk_continue(struct fib6_walker *w)
1517 {
1518         struct fib6_node *fn, *pn;
1519
1520         for (;;) {
1521                 fn = w->node;
1522                 if (!fn)
1523                         return 0;
1524
1525                 if (w->prune && fn != w->root &&
1526                     fn->fn_flags & RTN_RTINFO && w->state < FWS_C) {
1527                         w->state = FWS_C;
1528                         w->leaf = fn->leaf;
1529                 }
1530                 switch (w->state) {
1531 #ifdef CONFIG_IPV6_SUBTREES
1532                 case FWS_S:
1533                         if (FIB6_SUBTREE(fn)) {
1534                                 w->node = FIB6_SUBTREE(fn);
1535                                 continue;
1536                         }
1537                         w->state = FWS_L;
1538 #endif
1539                 case FWS_L:
1540                         if (fn->left) {
1541                                 w->node = fn->left;
1542                                 w->state = FWS_INIT;
1543                                 continue;
1544                         }
1545                         w->state = FWS_R;
1546                 case FWS_R:
1547                         if (fn->right) {
1548                                 w->node = fn->right;
1549                                 w->state = FWS_INIT;
1550                                 continue;
1551                         }
1552                         w->state = FWS_C;
1553                         w->leaf = fn->leaf;
1554                 case FWS_C:
1555                         if (w->leaf && fn->fn_flags & RTN_RTINFO) {
1556                                 int err;
1557
1558                                 if (w->skip) {
1559                                         w->skip--;
1560                                         goto skip;
1561                                 }
1562
1563                                 err = w->func(w);
1564                                 if (err)
1565                                         return err;
1566
1567                                 w->count++;
1568                                 continue;
1569                         }
1570 skip:
1571                         w->state = FWS_U;
1572                 case FWS_U:
1573                         if (fn == w->root)
1574                                 return 0;
1575                         pn = fn->parent;
1576                         w->node = pn;
1577 #ifdef CONFIG_IPV6_SUBTREES
1578                         if (FIB6_SUBTREE(pn) == fn) {
1579                                 WARN_ON(!(fn->fn_flags & RTN_ROOT));
1580                                 w->state = FWS_L;
1581                                 continue;
1582                         }
1583 #endif
1584                         if (pn->left == fn) {
1585                                 w->state = FWS_R;
1586                                 continue;
1587                         }
1588                         if (pn->right == fn) {
1589                                 w->state = FWS_C;
1590                                 w->leaf = w->node->leaf;
1591                                 continue;
1592                         }
1593 #if RT6_DEBUG >= 2
1594                         WARN_ON(1);
1595 #endif
1596                 }
1597         }
1598 }
1599
1600 static int fib6_walk(struct net *net, struct fib6_walker *w)
1601 {
1602         int res;
1603
1604         w->state = FWS_INIT;
1605         w->node = w->root;
1606
1607         fib6_walker_link(net, w);
1608         res = fib6_walk_continue(w);
1609         if (res <= 0)
1610                 fib6_walker_unlink(net, w);
1611         return res;
1612 }
1613
1614 static int fib6_clean_node(struct fib6_walker *w)
1615 {
1616         int res;
1617         struct rt6_info *rt;
1618         struct fib6_cleaner *c = container_of(w, struct fib6_cleaner, w);
1619         struct nl_info info = {
1620                 .nl_net = c->net,
1621         };
1622
1623         if (c->sernum != FIB6_NO_SERNUM_CHANGE &&
1624             w->node->fn_sernum != c->sernum)
1625                 w->node->fn_sernum = c->sernum;
1626
1627         if (!c->func) {
1628                 WARN_ON_ONCE(c->sernum == FIB6_NO_SERNUM_CHANGE);
1629                 w->leaf = NULL;
1630                 return 0;
1631         }
1632
1633         for (rt = w->leaf; rt; rt = rt->dst.rt6_next) {
1634                 res = c->func(rt, c->arg);
1635                 if (res < 0) {
1636                         w->leaf = rt;
1637                         res = fib6_del(rt, &info);
1638                         if (res) {
1639 #if RT6_DEBUG >= 2
1640                                 pr_debug("%s: del failed: rt=%p@%p err=%d\n",
1641                                          __func__, rt, rt->rt6i_node, res);
1642 #endif
1643                                 continue;
1644                         }
1645                         return 0;
1646                 }
1647                 WARN_ON(res != 0);
1648         }
1649         w->leaf = rt;
1650         return 0;
1651 }
1652
1653 /*
1654  *      Convenient frontend to tree walker.
1655  *
1656  *      func is called on each route.
1657  *              It may return -1 -> delete this route.
1658  *                            0  -> continue walking
1659  *
1660  *      prune==1 -> only immediate children of node (certainly,
1661  *      ignoring pure split nodes) will be scanned.
1662  */
1663
1664 static void fib6_clean_tree(struct net *net, struct fib6_node *root,
1665                             int (*func)(struct rt6_info *, void *arg),
1666                             bool prune, int sernum, void *arg)
1667 {
1668         struct fib6_cleaner c;
1669
1670         c.w.root = root;
1671         c.w.func = fib6_clean_node;
1672         c.w.prune = prune;
1673         c.w.count = 0;
1674         c.w.skip = 0;
1675         c.func = func;
1676         c.sernum = sernum;
1677         c.arg = arg;
1678         c.net = net;
1679
1680         fib6_walk(net, &c.w);
1681 }
1682
1683 static void __fib6_clean_all(struct net *net,
1684                              int (*func)(struct rt6_info *, void *),
1685                              int sernum, void *arg)
1686 {
1687         struct fib6_table *table;
1688         struct hlist_head *head;
1689         unsigned int h;
1690
1691         rcu_read_lock();
1692         for (h = 0; h < FIB6_TABLE_HASHSZ; h++) {
1693                 head = &net->ipv6.fib_table_hash[h];
1694                 hlist_for_each_entry_rcu(table, head, tb6_hlist) {
1695                         write_lock_bh(&table->tb6_lock);
1696                         fib6_clean_tree(net, &table->tb6_root,
1697                                         func, false, sernum, arg);
1698                         write_unlock_bh(&table->tb6_lock);
1699                 }
1700         }
1701         rcu_read_unlock();
1702 }
1703
1704 void fib6_clean_all(struct net *net, int (*func)(struct rt6_info *, void *),
1705                     void *arg)
1706 {
1707         __fib6_clean_all(net, func, FIB6_NO_SERNUM_CHANGE, arg);
1708 }
1709
1710 static int fib6_prune_clone(struct rt6_info *rt, void *arg)
1711 {
1712         if (rt->rt6i_flags & RTF_CACHE) {
1713                 RT6_TRACE("pruning clone %p\n", rt);
1714                 return -1;
1715         }
1716
1717         return 0;
1718 }
1719
1720 static void fib6_prune_clones(struct net *net, struct fib6_node *fn)
1721 {
1722         fib6_clean_tree(net, fn, fib6_prune_clone, true,
1723                         FIB6_NO_SERNUM_CHANGE, NULL);
1724 }
1725
1726 static void fib6_flush_trees(struct net *net)
1727 {
1728         int new_sernum = fib6_new_sernum(net);
1729
1730         __fib6_clean_all(net, NULL, new_sernum, NULL);
1731 }
1732
1733 /*
1734  *      Garbage collection
1735  */
1736
1737 struct fib6_gc_args
1738 {
1739         int                     timeout;
1740         int                     more;
1741 };
1742
1743 static int fib6_age(struct rt6_info *rt, void *arg)
1744 {
1745         struct fib6_gc_args *gc_args = arg;
1746         unsigned long now = jiffies;
1747
1748         /*
1749          *      check addrconf expiration here.
1750          *      Routes are expired even if they are in use.
1751          *
1752          *      Also age clones. Note, that clones are aged out
1753          *      only if they are not in use now.
1754          */
1755
1756         if (rt->rt6i_flags & RTF_EXPIRES && rt->dst.expires) {
1757                 if (time_after(now, rt->dst.expires)) {
1758                         RT6_TRACE("expiring %p\n", rt);
1759                         return -1;
1760                 }
1761                 gc_args->more++;
1762         } else if (rt->rt6i_flags & RTF_CACHE) {
1763                 if (atomic_read(&rt->dst.__refcnt) == 0 &&
1764                     time_after_eq(now, rt->dst.lastuse + gc_args->timeout)) {
1765                         RT6_TRACE("aging clone %p\n", rt);
1766                         return -1;
1767                 } else if (rt->rt6i_flags & RTF_GATEWAY) {
1768                         struct neighbour *neigh;
1769                         __u8 neigh_flags = 0;
1770
1771                         neigh = dst_neigh_lookup(&rt->dst, &rt->rt6i_gateway);
1772                         if (neigh) {
1773                                 neigh_flags = neigh->flags;
1774                                 neigh_release(neigh);
1775                         }
1776                         if (!(neigh_flags & NTF_ROUTER)) {
1777                                 RT6_TRACE("purging route %p via non-router but gateway\n",
1778                                           rt);
1779                                 return -1;
1780                         }
1781                 }
1782                 gc_args->more++;
1783         }
1784
1785         return 0;
1786 }
1787
1788 void fib6_run_gc(unsigned long expires, struct net *net, bool force)
1789 {
1790         struct fib6_gc_args gc_args;
1791         unsigned long now;
1792
1793         if (force) {
1794                 spin_lock_bh(&net->ipv6.fib6_gc_lock);
1795         } else if (!spin_trylock_bh(&net->ipv6.fib6_gc_lock)) {
1796                 mod_timer(&net->ipv6.ip6_fib_timer, jiffies + HZ);
1797                 return;
1798         }
1799         gc_args.timeout = expires ? (int)expires :
1800                           net->ipv6.sysctl.ip6_rt_gc_interval;
1801
1802         gc_args.more = icmp6_dst_gc();
1803
1804         fib6_clean_all(net, fib6_age, &gc_args);
1805         now = jiffies;
1806         net->ipv6.ip6_rt_last_gc = now;
1807
1808         if (gc_args.more)
1809                 mod_timer(&net->ipv6.ip6_fib_timer,
1810                           round_jiffies(now
1811                                         + net->ipv6.sysctl.ip6_rt_gc_interval));
1812         else
1813                 del_timer(&net->ipv6.ip6_fib_timer);
1814         spin_unlock_bh(&net->ipv6.fib6_gc_lock);
1815 }
1816
1817 static void fib6_gc_timer_cb(unsigned long arg)
1818 {
1819         fib6_run_gc(0, (struct net *)arg, true);
1820 }
1821
1822 static int __net_init fib6_net_init(struct net *net)
1823 {
1824         size_t size = sizeof(struct hlist_head) * FIB6_TABLE_HASHSZ;
1825
1826         spin_lock_init(&net->ipv6.fib6_gc_lock);
1827         rwlock_init(&net->ipv6.fib6_walker_lock);
1828         INIT_LIST_HEAD(&net->ipv6.fib6_walkers);
1829         setup_timer(&net->ipv6.ip6_fib_timer, fib6_gc_timer_cb, (unsigned long)net);
1830
1831         net->ipv6.rt6_stats = kzalloc(sizeof(*net->ipv6.rt6_stats), GFP_KERNEL);
1832         if (!net->ipv6.rt6_stats)
1833                 goto out_timer;
1834
1835         /* Avoid false sharing : Use at least a full cache line */
1836         size = max_t(size_t, size, L1_CACHE_BYTES);
1837
1838         net->ipv6.fib_table_hash = kzalloc(size, GFP_KERNEL);
1839         if (!net->ipv6.fib_table_hash)
1840                 goto out_rt6_stats;
1841
1842         net->ipv6.fib6_main_tbl = kzalloc(sizeof(*net->ipv6.fib6_main_tbl),
1843                                           GFP_KERNEL);
1844         if (!net->ipv6.fib6_main_tbl)
1845                 goto out_fib_table_hash;
1846
1847         net->ipv6.fib6_main_tbl->tb6_id = RT6_TABLE_MAIN;
1848         net->ipv6.fib6_main_tbl->tb6_root.leaf = net->ipv6.ip6_null_entry;
1849         net->ipv6.fib6_main_tbl->tb6_root.fn_flags =
1850                 RTN_ROOT | RTN_TL_ROOT | RTN_RTINFO;
1851         inet_peer_base_init(&net->ipv6.fib6_main_tbl->tb6_peers);
1852
1853 #ifdef CONFIG_IPV6_MULTIPLE_TABLES
1854         net->ipv6.fib6_local_tbl = kzalloc(sizeof(*net->ipv6.fib6_local_tbl),
1855                                            GFP_KERNEL);
1856         if (!net->ipv6.fib6_local_tbl)
1857                 goto out_fib6_main_tbl;
1858         net->ipv6.fib6_local_tbl->tb6_id = RT6_TABLE_LOCAL;
1859         net->ipv6.fib6_local_tbl->tb6_root.leaf = net->ipv6.ip6_null_entry;
1860         net->ipv6.fib6_local_tbl->tb6_root.fn_flags =
1861                 RTN_ROOT | RTN_TL_ROOT | RTN_RTINFO;
1862         inet_peer_base_init(&net->ipv6.fib6_local_tbl->tb6_peers);
1863 #endif
1864         fib6_tables_init(net);
1865
1866         return 0;
1867
1868 #ifdef CONFIG_IPV6_MULTIPLE_TABLES
1869 out_fib6_main_tbl:
1870         kfree(net->ipv6.fib6_main_tbl);
1871 #endif
1872 out_fib_table_hash:
1873         kfree(net->ipv6.fib_table_hash);
1874 out_rt6_stats:
1875         kfree(net->ipv6.rt6_stats);
1876 out_timer:
1877         return -ENOMEM;
1878 }
1879
1880 static void fib6_net_exit(struct net *net)
1881 {
1882         rt6_ifdown(net, NULL);
1883         del_timer_sync(&net->ipv6.ip6_fib_timer);
1884
1885 #ifdef CONFIG_IPV6_MULTIPLE_TABLES
1886         inetpeer_invalidate_tree(&net->ipv6.fib6_local_tbl->tb6_peers);
1887         kfree(net->ipv6.fib6_local_tbl);
1888 #endif
1889         inetpeer_invalidate_tree(&net->ipv6.fib6_main_tbl->tb6_peers);
1890         kfree(net->ipv6.fib6_main_tbl);
1891         kfree(net->ipv6.fib_table_hash);
1892         kfree(net->ipv6.rt6_stats);
1893 }
1894
1895 static struct pernet_operations fib6_net_ops = {
1896         .init = fib6_net_init,
1897         .exit = fib6_net_exit,
1898 };
1899
1900 int __init fib6_init(void)
1901 {
1902         int ret = -ENOMEM;
1903
1904         fib6_node_kmem = kmem_cache_create("fib6_nodes",
1905                                            sizeof(struct fib6_node),
1906                                            0, SLAB_HWCACHE_ALIGN,
1907                                            NULL);
1908         if (!fib6_node_kmem)
1909                 goto out;
1910
1911         ret = register_pernet_subsys(&fib6_net_ops);
1912         if (ret)
1913                 goto out_kmem_cache_create;
1914
1915         ret = __rtnl_register(PF_INET6, RTM_GETROUTE, NULL, inet6_dump_fib,
1916                               NULL);
1917         if (ret)
1918                 goto out_unregister_subsys;
1919
1920         __fib6_flush_trees = fib6_flush_trees;
1921 out:
1922         return ret;
1923
1924 out_unregister_subsys:
1925         unregister_pernet_subsys(&fib6_net_ops);
1926 out_kmem_cache_create:
1927         kmem_cache_destroy(fib6_node_kmem);
1928         goto out;
1929 }
1930
1931 void fib6_gc_cleanup(void)
1932 {
1933         unregister_pernet_subsys(&fib6_net_ops);
1934         kmem_cache_destroy(fib6_node_kmem);
1935 }
1936
1937 #ifdef CONFIG_PROC_FS
1938
1939 struct ipv6_route_iter {
1940         struct seq_net_private p;
1941         struct fib6_walker w;
1942         loff_t skip;
1943         struct fib6_table *tbl;
1944         int sernum;
1945 };
1946
1947 static int ipv6_route_seq_show(struct seq_file *seq, void *v)
1948 {
1949         struct rt6_info *rt = v;
1950         struct ipv6_route_iter *iter = seq->private;
1951
1952         seq_printf(seq, "%pi6 %02x ", &rt->rt6i_dst.addr, rt->rt6i_dst.plen);
1953
1954 #ifdef CONFIG_IPV6_SUBTREES
1955         seq_printf(seq, "%pi6 %02x ", &rt->rt6i_src.addr, rt->rt6i_src.plen);
1956 #else
1957         seq_puts(seq, "00000000000000000000000000000000 00 ");
1958 #endif
1959         if (rt->rt6i_flags & RTF_GATEWAY)
1960                 seq_printf(seq, "%pi6", &rt->rt6i_gateway);
1961         else
1962                 seq_puts(seq, "00000000000000000000000000000000");
1963
1964         seq_printf(seq, " %08x %08x %08x %08x %8s\n",
1965                    rt->rt6i_metric, atomic_read(&rt->dst.__refcnt),
1966                    rt->dst.__use, rt->rt6i_flags,
1967                    rt->dst.dev ? rt->dst.dev->name : "");
1968         iter->w.leaf = NULL;
1969         return 0;
1970 }
1971
1972 static int ipv6_route_yield(struct fib6_walker *w)
1973 {
1974         struct ipv6_route_iter *iter = w->args;
1975
1976         if (!iter->skip)
1977                 return 1;
1978
1979         do {
1980                 iter->w.leaf = iter->w.leaf->dst.rt6_next;
1981                 iter->skip--;
1982                 if (!iter->skip && iter->w.leaf)
1983                         return 1;
1984         } while (iter->w.leaf);
1985
1986         return 0;
1987 }
1988
1989 static void ipv6_route_seq_setup_walk(struct ipv6_route_iter *iter,
1990                                       struct net *net)
1991 {
1992         memset(&iter->w, 0, sizeof(iter->w));
1993         iter->w.func = ipv6_route_yield;
1994         iter->w.root = &iter->tbl->tb6_root;
1995         iter->w.state = FWS_INIT;
1996         iter->w.node = iter->w.root;
1997         iter->w.args = iter;
1998         iter->sernum = iter->w.root->fn_sernum;
1999         INIT_LIST_HEAD(&iter->w.lh);
2000         fib6_walker_link(net, &iter->w);
2001 }
2002
2003 static struct fib6_table *ipv6_route_seq_next_table(struct fib6_table *tbl,
2004                                                     struct net *net)
2005 {
2006         unsigned int h;
2007         struct hlist_node *node;
2008
2009         if (tbl) {
2010                 h = (tbl->tb6_id & (FIB6_TABLE_HASHSZ - 1)) + 1;
2011                 node = rcu_dereference_bh(hlist_next_rcu(&tbl->tb6_hlist));
2012         } else {
2013                 h = 0;
2014                 node = NULL;
2015         }
2016
2017         while (!node && h < FIB6_TABLE_HASHSZ) {
2018                 node = rcu_dereference_bh(
2019                         hlist_first_rcu(&net->ipv6.fib_table_hash[h++]));
2020         }
2021         return hlist_entry_safe(node, struct fib6_table, tb6_hlist);
2022 }
2023
2024 static void ipv6_route_check_sernum(struct ipv6_route_iter *iter)
2025 {
2026         if (iter->sernum != iter->w.root->fn_sernum) {
2027                 iter->sernum = iter->w.root->fn_sernum;
2028                 iter->w.state = FWS_INIT;
2029                 iter->w.node = iter->w.root;
2030                 WARN_ON(iter->w.skip);
2031                 iter->w.skip = iter->w.count;
2032         }
2033 }
2034
2035 static void *ipv6_route_seq_next(struct seq_file *seq, void *v, loff_t *pos)
2036 {
2037         int r;
2038         struct rt6_info *n;
2039         struct net *net = seq_file_net(seq);
2040         struct ipv6_route_iter *iter = seq->private;
2041
2042         if (!v)
2043                 goto iter_table;
2044
2045         n = ((struct rt6_info *)v)->dst.rt6_next;
2046         if (n) {
2047                 ++*pos;
2048                 return n;
2049         }
2050
2051 iter_table:
2052         ipv6_route_check_sernum(iter);
2053         read_lock(&iter->tbl->tb6_lock);
2054         r = fib6_walk_continue(&iter->w);
2055         read_unlock(&iter->tbl->tb6_lock);
2056         if (r > 0) {
2057                 if (v)
2058                         ++*pos;
2059                 return iter->w.leaf;
2060         } else if (r < 0) {
2061                 fib6_walker_unlink(net, &iter->w);
2062                 return NULL;
2063         }
2064         fib6_walker_unlink(net, &iter->w);
2065
2066         iter->tbl = ipv6_route_seq_next_table(iter->tbl, net);
2067         if (!iter->tbl)
2068                 return NULL;
2069
2070         ipv6_route_seq_setup_walk(iter, net);
2071         goto iter_table;
2072 }
2073
2074 static void *ipv6_route_seq_start(struct seq_file *seq, loff_t *pos)
2075         __acquires(RCU_BH)
2076 {
2077         struct net *net = seq_file_net(seq);
2078         struct ipv6_route_iter *iter = seq->private;
2079
2080         rcu_read_lock_bh();
2081         iter->tbl = ipv6_route_seq_next_table(NULL, net);
2082         iter->skip = *pos;
2083
2084         if (iter->tbl) {
2085                 ipv6_route_seq_setup_walk(iter, net);
2086                 return ipv6_route_seq_next(seq, NULL, pos);
2087         } else {
2088                 return NULL;
2089         }
2090 }
2091
2092 static bool ipv6_route_iter_active(struct ipv6_route_iter *iter)
2093 {
2094         struct fib6_walker *w = &iter->w;
2095         return w->node && !(w->state == FWS_U && w->node == w->root);
2096 }
2097
2098 static void ipv6_route_seq_stop(struct seq_file *seq, void *v)
2099         __releases(RCU_BH)
2100 {
2101         struct net *net = seq_file_net(seq);
2102         struct ipv6_route_iter *iter = seq->private;
2103
2104         if (ipv6_route_iter_active(iter))
2105                 fib6_walker_unlink(net, &iter->w);
2106
2107         rcu_read_unlock_bh();
2108 }
2109
2110 static const struct seq_operations ipv6_route_seq_ops = {
2111         .start  = ipv6_route_seq_start,
2112         .next   = ipv6_route_seq_next,
2113         .stop   = ipv6_route_seq_stop,
2114         .show   = ipv6_route_seq_show
2115 };
2116
2117 int ipv6_route_open(struct inode *inode, struct file *file)
2118 {
2119         return seq_open_net(inode, file, &ipv6_route_seq_ops,
2120                             sizeof(struct ipv6_route_iter));
2121 }
2122
2123 #endif /* CONFIG_PROC_FS */