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_free_pcpu(struct rt6_info *non_pcpu_rt)
 157 {
 158         int cpu;
 159
 160         if (!non_pcpu_rt->rt6i_pcpu)
 161                 return;
 162
 163         for_each_possible_cpu(cpu) {
 164                 struct rt6_info **ppcpu_rt;
 165                 struct rt6_info *pcpu_rt;
 166
 167                 ppcpu_rt = per_cpu_ptr(non_pcpu_rt->rt6i_pcpu, cpu);
 168                 pcpu_rt = *ppcpu_rt;
 169                 if (pcpu_rt) {
 170                         dst_dev_put(&pcpu_rt->dst);
 171                         dst_release(&pcpu_rt->dst);
 172                         *ppcpu_rt = NULL;
 173                 }
 174         }
 175
 176         free_percpu(non_pcpu_rt->rt6i_pcpu);
 177         non_pcpu_rt->rt6i_pcpu = NULL;
 178 }
 179
 180 static void rt6_release(struct rt6_info *rt)
 181 {
 182         if (atomic_dec_and_test(&rt->rt6i_ref)) {
 183                 rt6_free_pcpu(rt);
 184                 dst_dev_put(&rt->dst);
 185                 dst_release(&rt->dst);
 186         }
 187 }
 188
 189 static void fib6_link_table(struct net *net, struct fib6_table *tb)
 190 {
 191         unsigned int h;
 192
 193         /*
 194          * Initialize table lock at a single place to give lockdep a key,
 195          * tables aren't visible prior to being linked to the list.
 196          */
 197         rwlock_init(&tb->tb6_lock);
 198
 199         h = tb->tb6_id & (FIB6_TABLE_HASHSZ - 1);
 200
 201         /*
 202          * No protection necessary, this is the only list mutatation
 203          * operation, tables never disappear once they exist.
 204          */
 205         hlist_add_head_rcu(&tb->tb6_hlist, &net->ipv6.fib_table_hash[h]);
 206 }
 207
 208 #ifdef CONFIG_IPV6_MULTIPLE_TABLES
 209
 210 static struct fib6_table *fib6_alloc_table(struct net *net, u32 id)
 211 {
 212         struct fib6_table *table;
 213
 214         table = kzalloc(sizeof(*table), GFP_ATOMIC);
 215         if (table) {
 216                 table->tb6_id = id;
 217                 table->tb6_root.leaf = net->ipv6.ip6_null_entry;
 218                 table->tb6_root.fn_flags = RTN_ROOT | RTN_TL_ROOT | RTN_RTINFO;
 219                 inet_peer_base_init(&table->tb6_peers);
 220         }
 221
 222         return table;
 223 }
 224
 225 struct fib6_table *fib6_new_table(struct net *net, u32 id)
 226 {
 227         struct fib6_table *tb;
 228
 229         if (id == 0)
 230                 id = RT6_TABLE_MAIN;
 231         tb = fib6_get_table(net, id);
 232         if (tb)
 233                 return tb;
 234
 235         tb = fib6_alloc_table(net, id);
 236         if (tb)
 237                 fib6_link_table(net, tb);
 238
 239         return tb;
 240 }
 241 EXPORT_SYMBOL_GPL(fib6_new_table);
 242
 243 struct fib6_table *fib6_get_table(struct net *net, u32 id)
 244 {
 245         struct fib6_table *tb;
 246         struct hlist_head *head;
 247         unsigned int h;
 248
 249         if (id == 0)
 250                 id = RT6_TABLE_MAIN;
 251         h = id & (FIB6_TABLE_HASHSZ - 1);
 252         rcu_read_lock();
 253         head = &net->ipv6.fib_table_hash[h];
 254         hlist_for_each_entry_rcu(tb, head, tb6_hlist) {
 255                 if (tb->tb6_id == id) {
 256                         rcu_read_unlock();
 257                         return tb;
 258                 }
 259         }
 260         rcu_read_unlock();
 261
 262         return NULL;
 263 }
 264 EXPORT_SYMBOL_GPL(fib6_get_table);
 265
 266 static void __net_init fib6_tables_init(struct net *net)
 267 {
 268         fib6_link_table(net, net->ipv6.fib6_main_tbl);
 269         fib6_link_table(net, net->ipv6.fib6_local_tbl);
 270 }
 271 #else
 272
 273 struct fib6_table *fib6_new_table(struct net *net, u32 id)
 274 {
 275         return fib6_get_table(net, id);
 276 }
 277
 278 struct fib6_table *fib6_get_table(struct net *net, u32 id)
 279 {
 280           return net->ipv6.fib6_main_tbl;
 281 }
 282
 283 struct dst_entry *fib6_rule_lookup(struct net *net, struct flowi6 *fl6,
 284                                    int flags, pol_lookup_t lookup)
 285 {
 286         struct rt6_info *rt;
 287
 288         rt = lookup(net, net->ipv6.fib6_main_tbl, fl6, flags);
 289         if (rt->dst.error == -EAGAIN) {
 290                 ip6_rt_put(rt);
 291                 rt = net->ipv6.ip6_null_entry;
 292                 dst_hold(&rt->dst);
 293         }
 294
 295         return &rt->dst;
 296 }
 297
 298 static void __net_init fib6_tables_init(struct net *net)
 299 {
 300         fib6_link_table(net, net->ipv6.fib6_main_tbl);
 301 }
 302
 303 #endif
 304
 305 static int fib6_dump_node(struct fib6_walker *w)
 306 {
 307         int res;
 308         struct rt6_info *rt;
 309
 310         for (rt = w->leaf; rt; rt = rt->dst.rt6_next) {
 311                 res = rt6_dump_route(rt, w->args);
 312                 if (res < 0) {
 313                         /* Frame is full, suspend walking */
 314                         w->leaf = rt;
 315                         return 1;
 316                 }
 317
 318                 /* Multipath routes are dumped in one route with the
 319                  * RTA_MULTIPATH attribute. Jump 'rt' to point to the
 320                  * last sibling of this route (no need to dump the
 321                  * sibling routes again)
 322                  */
 323                 if (rt->rt6i_nsiblings)
 324                         rt = list_last_entry(&rt->rt6i_siblings,
 325                                              struct rt6_info,
 326                                              rt6i_siblings);
 327         }
 328         w->leaf = NULL;
 329         return 0;
 330 }
 331
 332 static void fib6_dump_end(struct netlink_callback *cb)
 333 {
 334         struct net *net = sock_net(cb->skb->sk);
 335         struct fib6_walker *w = (void *)cb->args[2];
 336
 337         if (w) {
 338                 if (cb->args[4]) {
 339                         cb->args[4] = 0;
 340                         fib6_walker_unlink(net, w);
 341                 }
 342                 cb->args[2] = 0;
 343                 kfree(w);
 344         }
 345         cb->done = (void *)cb->args[3];
 346         cb->args[1] = 3;
 347 }
 348
 349 static int fib6_dump_done(struct netlink_callback *cb)
 350 {
 351         fib6_dump_end(cb);
 352         return cb->done ? cb->done(cb) : 0;
 353 }
 354
 355 static int fib6_dump_table(struct fib6_table *table, struct sk_buff *skb,
 356                            struct netlink_callback *cb)
 357 {
 358         struct net *net = sock_net(skb->sk);
 359         struct fib6_walker *w;
 360         int res;
 361
 362         w = (void *)cb->args[2];
 363         w->root = &table->tb6_root;
 364
 365         if (cb->args[4] == 0) {
 366                 w->count = 0;
 367                 w->skip = 0;
 368
 369                 read_lock_bh(&table->tb6_lock);
 370                 res = fib6_walk(net, w);
 371                 read_unlock_bh(&table->tb6_lock);
 372                 if (res > 0) {
 373                         cb->args[4] = 1;
 374                         cb->args[5] = w->root->fn_sernum;
 375                 }
 376         } else {
 377                 if (cb->args[5] != w->root->fn_sernum) {
 378                         /* Begin at the root if the tree changed */
 379                         cb->args[5] = w->root->fn_sernum;
 380                         w->state = FWS_INIT;
 381                         w->node = w->root;
 382                         w->skip = w->count;
 383                 } else
 384                         w->skip = 0;
 385
 386                 read_lock_bh(&table->tb6_lock);
 387                 res = fib6_walk_continue(w);
 388                 read_unlock_bh(&table->tb6_lock);
 389                 if (res <= 0) {
 390                         fib6_walker_unlink(net, w);
 391                         cb->args[4] = 0;
 392                 }
 393         }
 394
 395         return res;
 396 }
 397
 398 static int inet6_dump_fib(struct sk_buff *skb, struct netlink_callback *cb)
 399 {
 400         struct net *net = sock_net(skb->sk);
 401         unsigned int h, s_h;
 402         unsigned int e = 0, s_e;
 403         struct rt6_rtnl_dump_arg arg;
 404         struct fib6_walker *w;
 405         struct fib6_table *tb;
 406         struct hlist_head *head;
 407         int res = 0;
 408
 409         s_h = cb->args[0];
 410         s_e = cb->args[1];
 411
 412         w = (void *)cb->args[2];
 413         if (!w) {
 414                 /* New dump:
 415                  *
 416                  * 1. hook callback destructor.
 417                  */
 418                 cb->args[3] = (long)cb->done;
 419                 cb->done = fib6_dump_done;
 420
 421                 /*
 422                  * 2. allocate and initialize walker.
 423                  */
 424                 w = kzalloc(sizeof(*w), GFP_ATOMIC);
 425                 if (!w)
 426                         return -ENOMEM;
 427                 w->func = fib6_dump_node;
 428                 cb->args[2] = (long)w;
 429         }
 430
 431         arg.skb = skb;
 432         arg.cb = cb;
 433         arg.net = net;
 434         w->args = &arg;
 435
 436         rcu_read_lock();
 437         for (h = s_h; h < FIB6_TABLE_HASHSZ; h++, s_e = 0) {
 438                 e = 0;
 439                 head = &net->ipv6.fib_table_hash[h];
 440                 hlist_for_each_entry_rcu(tb, head, tb6_hlist) {
 441                         if (e < s_e)
 442                                 goto next;
 443                         res = fib6_dump_table(tb, skb, cb);
 444                         if (res != 0)
 445                                 goto out;
 446 next:
 447                         e++;
 448                 }
 449         }
 450 out:
 451         rcu_read_unlock();
 452         cb->args[1] = e;
 453         cb->args[0] = h;
 454
 455         res = res < 0 ? res : skb->len;
 456         if (res <= 0)
 457                 fib6_dump_end(cb);
 458         return res;
 459 }
 460
 461 /*
 462  *      Routing Table
 463  *
 464  *      return the appropriate node for a routing tree "add" operation
 465  *      by either creating and inserting or by returning an existing
 466  *      node.
 467  */
 468
 469 static struct fib6_node *fib6_add_1(struct fib6_node *root,
 470                                      struct in6_addr *addr, int plen,
 471                                      int offset, int allow_create,
 472                                      int replace_required, int sernum,
 473                                      struct netlink_ext_ack *extack)
 474 {
 475         struct fib6_node *fn, *in, *ln;
 476         struct fib6_node *pn = NULL;
 477         struct rt6key *key;
 478         int     bit;
 479         __be32  dir = 0;
 480
 481         RT6_TRACE("fib6_add_1\n");
 482
 483         /* insert node in tree */
 484
 485         fn = root;
 486
 487         do {
 488                 key = (struct rt6key *)((u8 *)fn->leaf + offset);
 489
 490                 /*
 491                  *      Prefix match
 492                  */
 493                 if (plen < fn->fn_bit ||
 494                     !ipv6_prefix_equal(&key->addr, addr, fn->fn_bit)) {
 495                         if (!allow_create) {
 496                                 if (replace_required) {
 497                                         NL_SET_ERR_MSG(extack,
 498                                                        "Can not replace route - no match found");
 499                                         pr_warn("Can't replace route, no match found\n");
 500                                         return ERR_PTR(-ENOENT);
 501                                 }
 502                                 pr_warn("NLM_F_CREATE should be set when creating new route\n");
 503                         }
 504                         goto insert_above;
 505                 }
 506
 507                 /*
 508                  *      Exact match ?
 509                  */
 510
 511                 if (plen == fn->fn_bit) {
 512                         /* clean up an intermediate node */
 513                         if (!(fn->fn_flags & RTN_RTINFO)) {
 514                                 rt6_release(fn->leaf);
 515                                 fn->leaf = NULL;
 516                         }
 517
 518                         fn->fn_sernum = sernum;
 519
 520                         return fn;
 521                 }
 522
 523                 /*
 524                  *      We have more bits to go
 525                  */
 526
 527                 /* Try to walk down on tree. */
 528                 fn->fn_sernum = sernum;
 529                 dir = addr_bit_set(addr, fn->fn_bit);
 530                 pn = fn;
 531                 fn = dir ? fn->right : fn->left;
 532         } while (fn);
 533
 534         if (!allow_create) {
 535                 /* We should not create new node because
 536                  * NLM_F_REPLACE was specified without NLM_F_CREATE
 537                  * I assume it is safe to require NLM_F_CREATE when
 538                  * REPLACE flag is used! Later we may want to remove the
 539                  * check for replace_required, because according
 540                  * to netlink specification, NLM_F_CREATE
 541                  * MUST be specified if new route is created.
 542                  * That would keep IPv6 consistent with IPv4
 543                  */
 544                 if (replace_required) {
 545                         NL_SET_ERR_MSG(extack,
 546                                        "Can not replace route - no match found");
 547                         pr_warn("Can't replace route, no match found\n");
 548                         return ERR_PTR(-ENOENT);
 549                 }
 550                 pr_warn("NLM_F_CREATE should be set when creating new route\n");
 551         }
 552         /*
 553          *      We walked to the bottom of tree.
 554          *      Create new leaf node without children.
 555          */
 556
 557         ln = node_alloc();
 558
 559         if (!ln)
 560                 return ERR_PTR(-ENOMEM);
 561         ln->fn_bit = plen;
 562
 563         ln->parent = pn;
 564         ln->fn_sernum = sernum;
 565
 566         if (dir)
 567                 pn->right = ln;
 568         else
 569                 pn->left  = ln;
 570
 571         return ln;
 572
 573
 574 insert_above:
 575         /*
 576          * split since we don't have a common prefix anymore or
 577          * we have a less significant route.
 578          * we've to insert an intermediate node on the list
 579          * this new node will point to the one we need to create
 580          * and the current
 581          */
 582
 583         pn = fn->parent;
 584
 585         /* find 1st bit in difference between the 2 addrs.
 586
 587            See comment in __ipv6_addr_diff: bit may be an invalid value,
 588            but if it is >= plen, the value is ignored in any case.
 589          */
 590
 591         bit = __ipv6_addr_diff(addr, &key->addr, sizeof(*addr));
 592
 593         /*
 594          *              (intermediate)[in]
 595          *                /        \
 596          *      (new leaf node)[ln] (old node)[fn]
 597          */
 598         if (plen > bit) {
 599                 in = node_alloc();
 600                 ln = node_alloc();
 601
 602                 if (!in || !ln) {
 603                         if (in)
 604                                 node_free(in);
 605                         if (ln)
 606                                 node_free(ln);
 607                         return ERR_PTR(-ENOMEM);
 608                 }
 609
 610                 /*
 611                  * new intermediate node.
 612                  * RTN_RTINFO will
 613                  * be off since that an address that chooses one of
 614                  * the branches would not match less specific routes
 615                  * in the other branch
 616                  */
 617
 618                 in->fn_bit = bit;
 619
 620                 in->parent = pn;
 621                 in->leaf = fn->leaf;
 622                 atomic_inc(&in->leaf->rt6i_ref);
 623
 624                 in->fn_sernum = sernum;
 625
 626                 /* update parent pointer */
 627                 if (dir)
 628                         pn->right = in;
 629                 else
 630                         pn->left  = in;
 631
 632                 ln->fn_bit = plen;
 633
 634                 ln->parent = in;
 635                 fn->parent = in;
 636
 637                 ln->fn_sernum = sernum;
 638
 639                 if (addr_bit_set(addr, bit)) {
 640                         in->right = ln;
 641                         in->left  = fn;
 642                 } else {
 643                         in->left  = ln;
 644                         in->right = fn;
 645                 }
 646         } else { /* plen <= bit */
 647
 648                 /*
 649                  *              (new leaf node)[ln]
 650                  *                /        \
 651                  *           (old node)[fn] NULL
 652                  */
 653
 654                 ln = node_alloc();
 655
 656                 if (!ln)
 657                         return ERR_PTR(-ENOMEM);
 658
 659                 ln->fn_bit = plen;
 660
 661                 ln->parent = pn;
 662
 663                 ln->fn_sernum = sernum;
 664
 665                 if (dir)
 666                         pn->right = ln;
 667                 else
 668                         pn->left  = ln;
 669
 670                 if (addr_bit_set(&key->addr, plen))
 671                         ln->right = fn;
 672                 else
 673                         ln->left  = fn;
 674
 675                 fn->parent = ln;
 676         }
 677         return ln;
 678 }
 679
 680 static bool rt6_qualify_for_ecmp(struct rt6_info *rt)
 681 {
 682         return (rt->rt6i_flags & (RTF_GATEWAY|RTF_ADDRCONF|RTF_DYNAMIC)) ==
 683                RTF_GATEWAY;
 684 }
 685
 686 static void fib6_copy_metrics(u32 *mp, const struct mx6_config *mxc)
 687 {
 688         int i;
 689
 690         for (i = 0; i < RTAX_MAX; i++) {
 691                 if (test_bit(i, mxc->mx_valid))
 692                         mp[i] = mxc->mx[i];
 693         }
 694 }
 695
 696 static int fib6_commit_metrics(struct dst_entry *dst, struct mx6_config *mxc)
 697 {
 698         if (!mxc->mx)
 699                 return 0;
 700
 701         if (dst->flags & DST_HOST) {
 702                 u32 *mp = dst_metrics_write_ptr(dst);
 703
 704                 if (unlikely(!mp))
 705                         return -ENOMEM;
 706
 707                 fib6_copy_metrics(mp, mxc);
 708         } else {
 709                 dst_init_metrics(dst, mxc->mx, false);
 710
 711                 /* We've stolen mx now. */
 712                 mxc->mx = NULL;
 713         }
 714
 715         return 0;
 716 }
 717
 718 static void fib6_purge_rt(struct rt6_info *rt, struct fib6_node *fn,
 719                           struct net *net)
 720 {
 721         if (atomic_read(&rt->rt6i_ref) != 1) {
 722                 /* This route is used as dummy address holder in some split
 723                  * nodes. It is not leaked, but it still holds other resources,
 724                  * which must be released in time. So, scan ascendant nodes
 725                  * and replace dummy references to this route with references
 726                  * to still alive ones.
 727                  */
 728                 while (fn) {
 729                         if (!(fn->fn_flags & RTN_RTINFO) && fn->leaf == rt) {
 730                                 fn->leaf = fib6_find_prefix(net, fn);
 731                                 atomic_inc(&fn->leaf->rt6i_ref);
 732                                 rt6_release(rt);
 733                         }
 734                         fn = fn->parent;
 735                 }
 736                 /* No more references are possible at this point. */
 737                 BUG_ON(atomic_read(&rt->rt6i_ref) != 1);
 738         }
 739 }
 740
 741 /*
 742  *      Insert routing information in a node.
 743  */
 744
 745 static int fib6_add_rt2node(struct fib6_node *fn, struct rt6_info *rt,
 746                             struct nl_info *info, struct mx6_config *mxc)
 747 {
 748         struct rt6_info *iter = NULL;
 749         struct rt6_info **ins;
 750         struct rt6_info **fallback_ins = NULL;
 751         int replace = (info->nlh &&
 752                        (info->nlh->nlmsg_flags & NLM_F_REPLACE));
 753         int add = (!info->nlh ||
 754                    (info->nlh->nlmsg_flags & NLM_F_CREATE));
 755         int found = 0;
 756         bool rt_can_ecmp = rt6_qualify_for_ecmp(rt);
 757         u16 nlflags = NLM_F_EXCL;
 758         int err;
 759
 760         if (info->nlh && (info->nlh->nlmsg_flags & NLM_F_APPEND))
 761                 nlflags |= NLM_F_APPEND;
 762
 763         ins = &fn->leaf;
 764
 765         for (iter = fn->leaf; iter; iter = iter->dst.rt6_next) {
 766                 /*
 767                  *      Search for duplicates
 768                  */
 769
 770                 if (iter->rt6i_metric == rt->rt6i_metric) {
 771                         /*
 772                          *      Same priority level
 773                          */
 774                         if (info->nlh &&
 775                             (info->nlh->nlmsg_flags & NLM_F_EXCL))
 776                                 return -EEXIST;
 777
 778                         nlflags &= ~NLM_F_EXCL;
 779                         if (replace) {
 780                                 if (rt_can_ecmp == rt6_qualify_for_ecmp(iter)) {
 781                                         found++;
 782                                         break;
 783                                 }
 784                                 if (rt_can_ecmp)
 785                                         fallback_ins = fallback_ins ?: ins;
 786                                 goto next_iter;
 787                         }
 788
 789                         if (rt6_duplicate_nexthop(iter, rt)) {
 790                                 if (rt->rt6i_nsiblings)
 791                                         rt->rt6i_nsiblings = 0;
 792                                 if (!(iter->rt6i_flags & RTF_EXPIRES))
 793                                         return -EEXIST;
 794                                 if (!(rt->rt6i_flags & RTF_EXPIRES))
 795                                         rt6_clean_expires(iter);
 796                                 else
 797                                         rt6_set_expires(iter, rt->dst.expires);
 798                                 iter->rt6i_pmtu = rt->rt6i_pmtu;
 799                                 return -EEXIST;
 800                         }
 801                         /* If we have the same destination and the same metric,
 802                          * but not the same gateway, then the route we try to
 803                          * add is sibling to this route, increment our counter
 804                          * of siblings, and later we will add our route to the
 805                          * list.
 806                          * Only static routes (which don't have flag
 807                          * RTF_EXPIRES) are used for ECMPv6.
 808                          *
 809                          * To avoid long list, we only had siblings if the
 810                          * route have a gateway.
 811                          */
 812                         if (rt_can_ecmp &&
 813                             rt6_qualify_for_ecmp(iter))
 814                                 rt->rt6i_nsiblings++;
 815                 }
 816
 817                 if (iter->rt6i_metric > rt->rt6i_metric)
 818                         break;
 819
 820 next_iter:
 821                 ins = &iter->dst.rt6_next;
 822         }
 823
 824         if (fallback_ins && !found) {
 825                 /* No ECMP-able route found, replace first non-ECMP one */
 826                 ins = fallback_ins;
 827                 iter = *ins;
 828                 found++;
 829         }
 830
 831         /* Reset round-robin state, if necessary */
 832         if (ins == &fn->leaf)
 833                 fn->rr_ptr = NULL;
 834
 835         /* Link this route to others same route. */
 836         if (rt->rt6i_nsiblings) {
 837                 unsigned int rt6i_nsiblings;
 838                 struct rt6_info *sibling, *temp_sibling;
 839
 840                 /* Find the first route that have the same metric */
 841                 sibling = fn->leaf;
 842                 while (sibling) {
 843                         if (sibling->rt6i_metric == rt->rt6i_metric &&
 844                             rt6_qualify_for_ecmp(sibling)) {
 845                                 list_add_tail(&rt->rt6i_siblings,
 846                                               &sibling->rt6i_siblings);
 847                                 break;
 848                         }
 849                         sibling = sibling->dst.rt6_next;
 850                 }
 851                 /* For each sibling in the list, increment the counter of
 852                  * siblings. BUG() if counters does not match, list of siblings
 853                  * is broken!
 854                  */
 855                 rt6i_nsiblings = 0;
 856                 list_for_each_entry_safe(sibling, temp_sibling,
 857                                          &rt->rt6i_siblings, rt6i_siblings) {
 858                         sibling->rt6i_nsiblings++;
 859                         BUG_ON(sibling->rt6i_nsiblings != rt->rt6i_nsiblings);
 860                         rt6i_nsiblings++;
 861                 }
 862                 BUG_ON(rt6i_nsiblings != rt->rt6i_nsiblings);
 863         }
 864
 865         /*
 866          *      insert node
 867          */
 868         if (!replace) {
 869                 if (!add)
 870                         pr_warn("NLM_F_CREATE should be set when creating new route\n");
 871
 872 add:
 873                 nlflags |= NLM_F_CREATE;
 874                 err = fib6_commit_metrics(&rt->dst, mxc);
 875                 if (err)
 876                         return err;
 877
 878                 rt->dst.rt6_next = iter;
 879                 *ins = rt;
 880                 rt->rt6i_node = fn;
 881                 atomic_inc(&rt->rt6i_ref);
 882                 if (!info->skip_notify)
 883                         inet6_rt_notify(RTM_NEWROUTE, rt, info, nlflags);
 884                 info->nl_net->ipv6.rt6_stats->fib_rt_entries++;
 885
 886                 if (!(fn->fn_flags & RTN_RTINFO)) {
 887                         info->nl_net->ipv6.rt6_stats->fib_route_nodes++;
 888                         fn->fn_flags |= RTN_RTINFO;
 889                 }
 890
 891         } else {
 892                 int nsiblings;
 893
 894                 if (!found) {
 895                         if (add)
 896                                 goto add;
 897                         pr_warn("NLM_F_REPLACE set, but no existing node found!\n");
 898                         return -ENOENT;
 899                 }
 900
 901                 err = fib6_commit_metrics(&rt->dst, mxc);
 902                 if (err)
 903                         return err;
 904
 905                 *ins = rt;
 906                 rt->rt6i_node = fn;
 907                 rt->dst.rt6_next = iter->dst.rt6_next;
 908                 atomic_inc(&rt->rt6i_ref);
 909                 if (!info->skip_notify)
 910                         inet6_rt_notify(RTM_NEWROUTE, rt, info, NLM_F_REPLACE);
 911                 if (!(fn->fn_flags & RTN_RTINFO)) {
 912                         info->nl_net->ipv6.rt6_stats->fib_route_nodes++;
 913                         fn->fn_flags |= RTN_RTINFO;
 914                 }
 915                 nsiblings = iter->rt6i_nsiblings;
 916                 fib6_purge_rt(iter, fn, info->nl_net);
 917                 rt6_release(iter);
 918
 919                 if (nsiblings) {
 920                         /* Replacing an ECMP route, remove all siblings */
 921                         ins = &rt->dst.rt6_next;
 922                         iter = *ins;
 923                         while (iter) {
 924                                 if (iter->rt6i_metric > rt->rt6i_metric)
 925                                         break;
 926                                 if (rt6_qualify_for_ecmp(iter)) {
 927                                         *ins = iter->dst.rt6_next;
 928                                         fib6_purge_rt(iter, fn, info->nl_net);
 929                                         rt6_release(iter);
 930                                         nsiblings--;
 931                                 } else {
 932                                         ins = &iter->dst.rt6_next;
 933                                 }
 934                                 iter = *ins;
 935                         }
 936                         WARN_ON(nsiblings != 0);
 937                 }
 938         }
 939
 940         return 0;
 941 }
 942
 943 static void fib6_start_gc(struct net *net, struct rt6_info *rt)
 944 {
 945         if (!timer_pending(&net->ipv6.ip6_fib_timer) &&
 946             (rt->rt6i_flags & (RTF_EXPIRES | RTF_CACHE)))
 947                 mod_timer(&net->ipv6.ip6_fib_timer,
 948                           jiffies + net->ipv6.sysctl.ip6_rt_gc_interval);
 949 }
 950
 951 void fib6_force_start_gc(struct net *net)
 952 {
 953         if (!timer_pending(&net->ipv6.ip6_fib_timer))
 954                 mod_timer(&net->ipv6.ip6_fib_timer,
 955                           jiffies + net->ipv6.sysctl.ip6_rt_gc_interval);
 956 }
 957
 958 /*
 959  *      Add routing information to the routing tree.
 960  *      <destination addr>/<source addr>
 961  *      with source addr info in sub-trees
 962  */
 963
 964 int fib6_add(struct fib6_node *root, struct rt6_info *rt,
 965              struct nl_info *info, struct mx6_config *mxc,
 966              struct netlink_ext_ack *extack)
 967 {
 968         struct fib6_node *fn, *pn = NULL;
 969         int err = -ENOMEM;
 970         int allow_create = 1;
 971         int replace_required = 0;
 972         int sernum = fib6_new_sernum(info->nl_net);
 973
 974         if (WARN_ON_ONCE(!atomic_read(&rt->dst.__refcnt)))
 975                 return -EINVAL;
 976
 977         if (info->nlh) {
 978                 if (!(info->nlh->nlmsg_flags & NLM_F_CREATE))
 979                         allow_create = 0;
 980                 if (info->nlh->nlmsg_flags & NLM_F_REPLACE)
 981                         replace_required = 1;
 982         }
 983         if (!allow_create && !replace_required)
 984                 pr_warn("RTM_NEWROUTE with no NLM_F_CREATE or NLM_F_REPLACE\n");
 985
 986         fn = fib6_add_1(root, &rt->rt6i_dst.addr, rt->rt6i_dst.plen,
 987                         offsetof(struct rt6_info, rt6i_dst), allow_create,
 988                         replace_required, sernum, extack);
 989         if (IS_ERR(fn)) {
 990                 err = PTR_ERR(fn);
 991                 fn = NULL;
 992                 goto out;
 993         }
 994
 995         pn = fn;
 996
 997 #ifdef CONFIG_IPV6_SUBTREES
 998         if (rt->rt6i_src.plen) {
 999                 struct fib6_node *sn;
1000
1001                 if (!fn->subtree) {
1002                         struct fib6_node *sfn;
1003
1004                         /*
1005                          * Create subtree.
1006                          *
1007                          *              fn[main tree]
1008                          *              |
1009                          *              sfn[subtree root]
1010                          *                 \
1011                          *                  sn[new leaf node]
1012                          */
1013
1014                         /* Create subtree root node */
1015                         sfn = node_alloc();
1016                         if (!sfn)
1017                                 goto st_failure;
1018
1019                         sfn->leaf = info->nl_net->ipv6.ip6_null_entry;
1020                         atomic_inc(&info->nl_net->ipv6.ip6_null_entry->rt6i_ref);
1021                         sfn->fn_flags = RTN_ROOT;
1022                         sfn->fn_sernum = sernum;
1023
1024                         /* Now add the first leaf node to new subtree */
1025
1026                         sn = fib6_add_1(sfn, &rt->rt6i_src.addr,
1027                                         rt->rt6i_src.plen,
1028                                         offsetof(struct rt6_info, rt6i_src),
1029                                         allow_create, replace_required, sernum,
1030                                         extack);
1031
1032                         if (IS_ERR(sn)) {
1033                                 /* If it is failed, discard just allocated
1034                                    root, and then (in st_failure) stale node
1035                                    in main tree.
1036                                  */
1037                                 node_free(sfn);
1038                                 err = PTR_ERR(sn);
1039                                 goto st_failure;
1040                         }
1041
1042                         /* Now link new subtree to main tree */
1043                         sfn->parent = fn;
1044                         fn->subtree = sfn;
1045                 } else {
1046                         sn = fib6_add_1(fn->subtree, &rt->rt6i_src.addr,
1047                                         rt->rt6i_src.plen,
1048                                         offsetof(struct rt6_info, rt6i_src),
1049                                         allow_create, replace_required, sernum,
1050                                         extack);
1051
1052                         if (IS_ERR(sn)) {
1053                                 err = PTR_ERR(sn);
1054                                 goto st_failure;
1055                         }
1056                 }
1057
1058                 if (!fn->leaf) {
1059                         fn->leaf = rt;
1060                         atomic_inc(&rt->rt6i_ref);
1061                 }
1062                 fn = sn;
1063         }
1064 #endif
1065
1066         err = fib6_add_rt2node(fn, rt, info, mxc);
1067         if (!err) {
1068                 fib6_start_gc(info->nl_net, rt);
1069                 if (!(rt->rt6i_flags & RTF_CACHE))
1070                         fib6_prune_clones(info->nl_net, pn);
1071         }
1072
1073 out:
1074         if (err) {
1075 #ifdef CONFIG_IPV6_SUBTREES
1076                 /*
1077                  * If fib6_add_1 has cleared the old leaf pointer in the
1078                  * super-tree leaf node we have to find a new one for it.
1079                  */
1080                 if (pn != fn && pn->leaf == rt) {
1081                         pn->leaf = NULL;
1082                         atomic_dec(&rt->rt6i_ref);
1083                 }
1084                 if (pn != fn && !pn->leaf && !(pn->fn_flags & RTN_RTINFO)) {
1085                         pn->leaf = fib6_find_prefix(info->nl_net, pn);
1086 #if RT6_DEBUG >= 2
1087                         if (!pn->leaf) {
1088                                 WARN_ON(pn->leaf == NULL);
1089                                 pn->leaf = info->nl_net->ipv6.ip6_null_entry;
1090                         }
1091 #endif
1092                         atomic_inc(&pn->leaf->rt6i_ref);
1093                 }
1094 #endif
1095                 /* Always release dst as dst->__refcnt is guaranteed
1096                  * to be taken before entering this function
1097                  */
1098                 dst_release_immediate(&rt->dst);
1099         }
1100         return err;
1101
1102 #ifdef CONFIG_IPV6_SUBTREES
1103         /* Subtree creation failed, probably main tree node
1104            is orphan. If it is, shoot it.
1105          */
1106 st_failure:
1107         if (fn && !(fn->fn_flags & (RTN_RTINFO|RTN_ROOT)))
1108                 fib6_repair_tree(info->nl_net, fn);
1109         /* Always release dst as dst->__refcnt is guaranteed
1110          * to be taken before entering this function
1111          */
1112         dst_release_immediate(&rt->dst);
1113         return err;
1114 #endif
1115 }
1116
1117 /*
1118  *      Routing tree lookup
1119  *
1120  */
1121
1122 struct lookup_args {
1123         int                     offset;         /* key offset on rt6_info       */
1124         const struct in6_addr   *addr;          /* search key                   */
1125 };
1126
1127 static struct fib6_node *fib6_lookup_1(struct fib6_node *root,
1128                                        struct lookup_args *args)
1129 {
1130         struct fib6_node *fn;
1131         __be32 dir;
1132
1133         if (unlikely(args->offset == 0))
1134                 return NULL;
1135
1136         /*
1137          *      Descend on a tree
1138          */
1139
1140         fn = root;
1141
1142         for (;;) {
1143                 struct fib6_node *next;
1144
1145                 dir = addr_bit_set(args->addr, fn->fn_bit);
1146
1147                 next = dir ? fn->right : fn->left;
1148
1149                 if (next) {
1150                         fn = next;
1151                         continue;
1152                 }
1153                 break;
1154         }
1155
1156         while (fn) {
1157                 if (FIB6_SUBTREE(fn) || fn->fn_flags & RTN_RTINFO) {
1158                         struct rt6key *key;
1159
1160                         key = (struct rt6key *) ((u8 *) fn->leaf +
1161                                                  args->offset);
1162
1163                         if (ipv6_prefix_equal(&key->addr, args->addr, key->plen)) {
1164 #ifdef CONFIG_IPV6_SUBTREES
1165                                 if (fn->subtree) {
1166                                         struct fib6_node *sfn;
1167                                         sfn = fib6_lookup_1(fn->subtree,
1168                                                             args + 1);
1169                                         if (!sfn)
1170                                                 goto backtrack;
1171                                         fn = sfn;
1172                                 }
1173 #endif
1174                                 if (fn->fn_flags & RTN_RTINFO)
1175                                         return fn;
1176                         }
1177                 }
1178 #ifdef CONFIG_IPV6_SUBTREES
1179 backtrack:
1180 #endif
1181                 if (fn->fn_flags & RTN_ROOT)
1182                         break;
1183
1184                 fn = fn->parent;
1185         }
1186
1187         return NULL;
1188 }
1189
1190 struct fib6_node *fib6_lookup(struct fib6_node *root, const struct in6_addr *daddr,
1191                               const struct in6_addr *saddr)
1192 {
1193         struct fib6_node *fn;
1194         struct lookup_args args[] = {
1195                 {
1196                         .offset = offsetof(struct rt6_info, rt6i_dst),
1197                         .addr = daddr,
1198                 },
1199 #ifdef CONFIG_IPV6_SUBTREES
1200                 {
1201                         .offset = offsetof(struct rt6_info, rt6i_src),
1202                         .addr = saddr,
1203                 },
1204 #endif
1205                 {
1206                         .offset = 0,    /* sentinel */
1207                 }
1208         };
1209
1210         fn = fib6_lookup_1(root, daddr ? args : args + 1);
1211         if (!fn || fn->fn_flags & RTN_TL_ROOT)
1212                 fn = root;
1213
1214         return fn;
1215 }
1216
1217 /*
1218  *      Get node with specified destination prefix (and source prefix,
1219  *      if subtrees are used)
1220  */
1221
1222
1223 static struct fib6_node *fib6_locate_1(struct fib6_node *root,
1224                                        const struct in6_addr *addr,
1225                                        int plen, int offset)
1226 {
1227         struct fib6_node *fn;
1228
1229         for (fn = root; fn ; ) {
1230                 struct rt6key *key = (struct rt6key *)((u8 *)fn->leaf + offset);
1231
1232                 /*
1233                  *      Prefix match
1234                  */
1235                 if (plen < fn->fn_bit ||
1236                     !ipv6_prefix_equal(&key->addr, addr, fn->fn_bit))
1237                         return NULL;
1238
1239                 if (plen == fn->fn_bit)
1240                         return fn;
1241
1242                 /*
1243                  *      We have more bits to go
1244                  */
1245                 if (addr_bit_set(addr, fn->fn_bit))
1246                         fn = fn->right;
1247                 else
1248                         fn = fn->left;
1249         }
1250         return NULL;
1251 }
1252
1253 struct fib6_node *fib6_locate(struct fib6_node *root,
1254                               const struct in6_addr *daddr, int dst_len,
1255                               const struct in6_addr *saddr, int src_len)
1256 {
1257         struct fib6_node *fn;
1258
1259         fn = fib6_locate_1(root, daddr, dst_len,
1260                            offsetof(struct rt6_info, rt6i_dst));
1261
1262 #ifdef CONFIG_IPV6_SUBTREES
1263         if (src_len) {
1264                 WARN_ON(saddr == NULL);
1265                 if (fn && fn->subtree)
1266                         fn = fib6_locate_1(fn->subtree, saddr, src_len,
1267                                            offsetof(struct rt6_info, rt6i_src));
1268         }
1269 #endif
1270
1271         if (fn && fn->fn_flags & RTN_RTINFO)
1272                 return fn;
1273
1274         return NULL;
1275 }
1276
1277
1278 /*
1279  *      Deletion
1280  *
1281  */
1282
1283 static struct rt6_info *fib6_find_prefix(struct net *net, struct fib6_node *fn)
1284 {
1285         if (fn->fn_flags & RTN_ROOT)
1286                 return net->ipv6.ip6_null_entry;
1287
1288         while (fn) {
1289                 if (fn->left)
1290                         return fn->left->leaf;
1291                 if (fn->right)
1292                         return fn->right->leaf;
1293
1294                 fn = FIB6_SUBTREE(fn);
1295         }
1296         return NULL;
1297 }
1298
1299 /*
1300  *      Called to trim the tree of intermediate nodes when possible. "fn"
1301  *      is the node we want to try and remove.
1302  */
1303
1304 static struct fib6_node *fib6_repair_tree(struct net *net,
1305                                            struct fib6_node *fn)
1306 {
1307         int children;
1308         int nstate;
1309         struct fib6_node *child, *pn;
1310         struct fib6_walker *w;
1311         int iter = 0;
1312
1313         for (;;) {
1314                 RT6_TRACE("fixing tree: plen=%d iter=%d\n", fn->fn_bit, iter);
1315                 iter++;
1316
1317                 WARN_ON(fn->fn_flags & RTN_RTINFO);
1318                 WARN_ON(fn->fn_flags & RTN_TL_ROOT);
1319                 WARN_ON(fn->leaf);
1320
1321                 children = 0;
1322                 child = NULL;
1323                 if (fn->right)
1324                         child = fn->right, children |= 1;
1325                 if (fn->left)
1326                         child = fn->left, children |= 2;
1327
1328                 if (children == 3 || FIB6_SUBTREE(fn)
1329 #ifdef CONFIG_IPV6_SUBTREES
1330                     /* Subtree root (i.e. fn) may have one child */
1331                     || (children && fn->fn_flags & RTN_ROOT)
1332 #endif
1333                     ) {
1334                         fn->leaf = fib6_find_prefix(net, fn);
1335 #if RT6_DEBUG >= 2
1336                         if (!fn->leaf) {
1337                                 WARN_ON(!fn->leaf);
1338                                 fn->leaf = net->ipv6.ip6_null_entry;
1339                         }
1340 #endif
1341                         atomic_inc(&fn->leaf->rt6i_ref);
1342                         return fn->parent;
1343                 }
1344
1345                 pn = fn->parent;
1346 #ifdef CONFIG_IPV6_SUBTREES
1347                 if (FIB6_SUBTREE(pn) == fn) {
1348                         WARN_ON(!(fn->fn_flags & RTN_ROOT));
1349                         FIB6_SUBTREE(pn) = NULL;
1350                         nstate = FWS_L;
1351                 } else {
1352                         WARN_ON(fn->fn_flags & RTN_ROOT);
1353 #endif
1354                         if (pn->right == fn)
1355                                 pn->right = child;
1356                         else if (pn->left == fn)
1357                                 pn->left = child;
1358 #if RT6_DEBUG >= 2
1359                         else
1360                                 WARN_ON(1);
1361 #endif
1362                         if (child)
1363                                 child->parent = pn;
1364                         nstate = FWS_R;
1365 #ifdef CONFIG_IPV6_SUBTREES
1366                 }
1367 #endif
1368
1369                 read_lock(&net->ipv6.fib6_walker_lock);
1370                 FOR_WALKERS(net, w) {
1371                         if (!child) {
1372                                 if (w->root == fn) {
1373                                         w->root = w->node = NULL;
1374                                         RT6_TRACE("W %p adjusted by delroot 1\n", w);
1375                                 } else if (w->node == fn) {
1376                                         RT6_TRACE("W %p adjusted by delnode 1, s=%d/%d\n", w, w->state, nstate);
1377                                         w->node = pn;
1378                                         w->state = nstate;
1379                                 }
1380                         } else {
1381                                 if (w->root == fn) {
1382                                         w->root = child;
1383                                         RT6_TRACE("W %p adjusted by delroot 2\n", w);
1384                                 }
1385                                 if (w->node == fn) {
1386                                         w->node = child;
1387                                         if (children&2) {
1388                                                 RT6_TRACE("W %p adjusted by delnode 2, s=%d\n", w, w->state);
1389                                                 w->state = w->state >= FWS_R ? FWS_U : FWS_INIT;
1390                                         } else {
1391                                                 RT6_TRACE("W %p adjusted by delnode 2, s=%d\n", w, w->state);
1392                                                 w->state = w->state >= FWS_C ? FWS_U : FWS_INIT;
1393                                         }
1394                                 }
1395                         }
1396                 }
1397                 read_unlock(&net->ipv6.fib6_walker_lock);
1398
1399                 node_free(fn);
1400                 if (pn->fn_flags & RTN_RTINFO || FIB6_SUBTREE(pn))
1401                         return pn;
1402
1403                 rt6_release(pn->leaf);
1404                 pn->leaf = NULL;
1405                 fn = pn;
1406         }
1407 }
1408
1409 static void fib6_del_route(struct fib6_node *fn, struct rt6_info **rtp,
1410                            struct nl_info *info)
1411 {
1412         struct fib6_walker *w;
1413         struct rt6_info *rt = *rtp;
1414         struct net *net = info->nl_net;
1415
1416         RT6_TRACE("fib6_del_route\n");
1417
1418         /* Unlink it */
1419         *rtp = rt->dst.rt6_next;
1420         rt->rt6i_node = NULL;
1421         net->ipv6.rt6_stats->fib_rt_entries--;
1422         net->ipv6.rt6_stats->fib_discarded_routes++;
1423
1424         /* Reset round-robin state, if necessary */
1425         if (fn->rr_ptr == rt)
1426                 fn->rr_ptr = NULL;
1427
1428         /* Remove this entry from other siblings */
1429         if (rt->rt6i_nsiblings) {
1430                 struct rt6_info *sibling, *next_sibling;
1431
1432                 list_for_each_entry_safe(sibling, next_sibling,
1433                                          &rt->rt6i_siblings, rt6i_siblings)
1434                         sibling->rt6i_nsiblings--;
1435                 rt->rt6i_nsiblings = 0;
1436                 list_del_init(&rt->rt6i_siblings);
1437         }
1438
1439         /* Adjust walkers */
1440         read_lock(&net->ipv6.fib6_walker_lock);
1441         FOR_WALKERS(net, w) {
1442                 if (w->state == FWS_C && w->leaf == rt) {
1443                         RT6_TRACE("walker %p adjusted by delroute\n", w);
1444                         w->leaf = rt->dst.rt6_next;
1445                         if (!w->leaf)
1446                                 w->state = FWS_U;
1447                 }
1448         }
1449         read_unlock(&net->ipv6.fib6_walker_lock);
1450
1451         rt->dst.rt6_next = NULL;
1452
1453         /* If it was last route, expunge its radix tree node */
1454         if (!fn->leaf) {
1455                 fn->fn_flags &= ~RTN_RTINFO;
1456                 net->ipv6.rt6_stats->fib_route_nodes--;
1457                 fn = fib6_repair_tree(net, fn);
1458         }
1459
1460         fib6_purge_rt(rt, fn, net);
1461
1462         if (!info->skip_notify)
1463                 inet6_rt_notify(RTM_DELROUTE, rt, info, 0);
1464         rt6_release(rt);
1465 }
1466
1467 int fib6_del(struct rt6_info *rt, struct nl_info *info)
1468 {
1469         struct net *net = info->nl_net;
1470         struct fib6_node *fn = rt->rt6i_node;
1471         struct rt6_info **rtp;
1472
1473 #if RT6_DEBUG >= 2
1474         if (rt->dst.obsolete > 0) {
1475                 WARN_ON(fn);
1476                 return -ENOENT;
1477         }
1478 #endif
1479         if (!fn || rt == net->ipv6.ip6_null_entry)
1480                 return -ENOENT;
1481
1482         WARN_ON(!(fn->fn_flags & RTN_RTINFO));
1483
1484         if (!(rt->rt6i_flags & RTF_CACHE)) {
1485                 struct fib6_node *pn = fn;
1486 #ifdef CONFIG_IPV6_SUBTREES
1487                 /* clones of this route might be in another subtree */
1488                 if (rt->rt6i_src.plen) {
1489                         while (!(pn->fn_flags & RTN_ROOT))
1490                                 pn = pn->parent;
1491                         pn = pn->parent;
1492                 }
1493 #endif
1494                 fib6_prune_clones(info->nl_net, pn);
1495         }
1496
1497         /*
1498          *      Walk the leaf entries looking for ourself
1499          */
1500
1501         for (rtp = &fn->leaf; *rtp; rtp = &(*rtp)->dst.rt6_next) {
1502                 if (*rtp == rt) {
1503                         fib6_del_route(fn, rtp, info);
1504                         return 0;
1505                 }
1506         }
1507         return -ENOENT;
1508 }
1509
1510 /*
1511  *      Tree traversal function.
1512  *
1513  *      Certainly, it is not interrupt safe.
1514  *      However, it is internally reenterable wrt itself and fib6_add/fib6_del.
1515  *      It means, that we can modify tree during walking
1516  *      and use this function for garbage collection, clone pruning,
1517  *      cleaning tree when a device goes down etc. etc.
1518  *
1519  *      It guarantees that every node will be traversed,
1520  *      and that it will be traversed only once.
1521  *
1522  *      Callback function w->func may return:
1523  *      0 -> continue walking.
1524  *      positive value -> walking is suspended (used by tree dumps,
1525  *      and probably by gc, if it will be split to several slices)
1526  *      negative value -> terminate walking.
1527  *
1528  *      The function itself returns:
1529  *      0   -> walk is complete.
1530  *      >0  -> walk is incomplete (i.e. suspended)
1531  *      <0  -> walk is terminated by an error.
1532  */
1533
1534 static int fib6_walk_continue(struct fib6_walker *w)
1535 {
1536         struct fib6_node *fn, *pn;
1537
1538         for (;;) {
1539                 fn = w->node;
1540                 if (!fn)
1541                         return 0;
1542
1543                 if (w->prune && fn != w->root &&
1544                     fn->fn_flags & RTN_RTINFO && w->state < FWS_C) {
1545                         w->state = FWS_C;
1546                         w->leaf = fn->leaf;
1547                 }
1548                 switch (w->state) {
1549 #ifdef CONFIG_IPV6_SUBTREES
1550                 case FWS_S:
1551                         if (FIB6_SUBTREE(fn)) {
1552                                 w->node = FIB6_SUBTREE(fn);
1553                                 continue;
1554                         }
1555                         w->state = FWS_L;
1556 #endif
1557                 case FWS_L:
1558                         if (fn->left) {
1559                                 w->node = fn->left;
1560                                 w->state = FWS_INIT;
1561                                 continue;
1562                         }
1563                         w->state = FWS_R;
1564                 case FWS_R:
1565                         if (fn->right) {
1566                                 w->node = fn->right;
1567                                 w->state = FWS_INIT;
1568                                 continue;
1569                         }
1570                         w->state = FWS_C;
1571                         w->leaf = fn->leaf;
1572                 case FWS_C:
1573                         if (w->leaf && fn->fn_flags & RTN_RTINFO) {
1574                                 int err;
1575
1576                                 if (w->skip) {
1577                                         w->skip--;
1578                                         goto skip;
1579                                 }
1580
1581                                 err = w->func(w);
1582                                 if (err)
1583                                         return err;
1584
1585                                 w->count++;
1586                                 continue;
1587                         }
1588 skip:
1589                         w->state = FWS_U;
1590                 case FWS_U:
1591                         if (fn == w->root)
1592                                 return 0;
1593                         pn = fn->parent;
1594                         w->node = pn;
1595 #ifdef CONFIG_IPV6_SUBTREES
1596                         if (FIB6_SUBTREE(pn) == fn) {
1597                                 WARN_ON(!(fn->fn_flags & RTN_ROOT));
1598                                 w->state = FWS_L;
1599                                 continue;
1600                         }
1601 #endif
1602                         if (pn->left == fn) {
1603                                 w->state = FWS_R;
1604                                 continue;
1605                         }
1606                         if (pn->right == fn) {
1607                                 w->state = FWS_C;
1608                                 w->leaf = w->node->leaf;
1609                                 continue;
1610                         }
1611 #if RT6_DEBUG >= 2
1612                         WARN_ON(1);
1613 #endif
1614                 }
1615         }
1616 }
1617
1618 static int fib6_walk(struct net *net, struct fib6_walker *w)
1619 {
1620         int res;
1621
1622         w->state = FWS_INIT;
1623         w->node = w->root;
1624
1625         fib6_walker_link(net, w);
1626         res = fib6_walk_continue(w);
1627         if (res <= 0)
1628                 fib6_walker_unlink(net, w);
1629         return res;
1630 }
1631
1632 static int fib6_clean_node(struct fib6_walker *w)
1633 {
1634         int res;
1635         struct rt6_info *rt;
1636         struct fib6_cleaner *c = container_of(w, struct fib6_cleaner, w);
1637         struct nl_info info = {
1638                 .nl_net = c->net,
1639         };
1640
1641         if (c->sernum != FIB6_NO_SERNUM_CHANGE &&
1642             w->node->fn_sernum != c->sernum)
1643                 w->node->fn_sernum = c->sernum;
1644
1645         if (!c->func) {
1646                 WARN_ON_ONCE(c->sernum == FIB6_NO_SERNUM_CHANGE);
1647                 w->leaf = NULL;
1648                 return 0;
1649         }
1650
1651         for (rt = w->leaf; rt; rt = rt->dst.rt6_next) {
1652                 res = c->func(rt, c->arg);
1653                 if (res < 0) {
1654                         w->leaf = rt;
1655                         res = fib6_del(rt, &info);
1656                         if (res) {
1657 #if RT6_DEBUG >= 2
1658                                 pr_debug("%s: del failed: rt=%p@%p err=%d\n",
1659                                          __func__, rt, rt->rt6i_node, res);
1660 #endif
1661                                 continue;
1662                         }
1663                         return 0;
1664                 }
1665                 WARN_ON(res != 0);
1666         }
1667         w->leaf = rt;
1668         return 0;
1669 }
1670
1671 /*
1672  *      Convenient frontend to tree walker.
1673  *
1674  *      func is called on each route.
1675  *              It may return -1 -> delete this route.
1676  *                            0  -> continue walking
1677  *
1678  *      prune==1 -> only immediate children of node (certainly,
1679  *      ignoring pure split nodes) will be scanned.
1680  */
1681
1682 static void fib6_clean_tree(struct net *net, struct fib6_node *root,
1683                             int (*func)(struct rt6_info *, void *arg),
1684                             bool prune, int sernum, void *arg)
1685 {
1686         struct fib6_cleaner c;
1687
1688         c.w.root = root;
1689         c.w.func = fib6_clean_node;
1690         c.w.prune = prune;
1691         c.w.count = 0;
1692         c.w.skip = 0;
1693         c.func = func;
1694         c.sernum = sernum;
1695         c.arg = arg;
1696         c.net = net;
1697
1698         fib6_walk(net, &c.w);
1699 }
1700
1701 static void __fib6_clean_all(struct net *net,
1702                              int (*func)(struct rt6_info *, void *),
1703                              int sernum, void *arg)
1704 {
1705         struct fib6_table *table;
1706         struct hlist_head *head;
1707         unsigned int h;
1708
1709         rcu_read_lock();
1710         for (h = 0; h < FIB6_TABLE_HASHSZ; h++) {
1711                 head = &net->ipv6.fib_table_hash[h];
1712                 hlist_for_each_entry_rcu(table, head, tb6_hlist) {
1713                         write_lock_bh(&table->tb6_lock);
1714                         fib6_clean_tree(net, &table->tb6_root,
1715                                         func, false, sernum, arg);
1716                         write_unlock_bh(&table->tb6_lock);
1717                 }
1718         }
1719         rcu_read_unlock();
1720 }
1721
1722 void fib6_clean_all(struct net *net, int (*func)(struct rt6_info *, void *),
1723                     void *arg)
1724 {
1725         __fib6_clean_all(net, func, FIB6_NO_SERNUM_CHANGE, arg);
1726 }
1727
1728 static int fib6_prune_clone(struct rt6_info *rt, void *arg)
1729 {
1730         if (rt->rt6i_flags & RTF_CACHE) {
1731                 RT6_TRACE("pruning clone %p\n", rt);
1732                 return -1;
1733         }
1734
1735         return 0;
1736 }
1737
1738 static void fib6_prune_clones(struct net *net, struct fib6_node *fn)
1739 {
1740         fib6_clean_tree(net, fn, fib6_prune_clone, true,
1741                         FIB6_NO_SERNUM_CHANGE, NULL);
1742 }
1743
1744 static void fib6_flush_trees(struct net *net)
1745 {
1746         int new_sernum = fib6_new_sernum(net);
1747
1748         __fib6_clean_all(net, NULL, new_sernum, NULL);
1749 }
1750
1751 /*
1752  *      Garbage collection
1753  */
1754
1755 struct fib6_gc_args
1756 {
1757         int                     timeout;
1758         int                     more;
1759 };
1760
1761 static int fib6_age(struct rt6_info *rt, void *arg)
1762 {
1763         struct fib6_gc_args *gc_args = arg;
1764         unsigned long now = jiffies;
1765
1766         /*
1767          *      check addrconf expiration here.
1768          *      Routes are expired even if they are in use.
1769          *
1770          *      Also age clones. Note, that clones are aged out
1771          *      only if they are not in use now.
1772          */
1773
1774         if (rt->rt6i_flags & RTF_EXPIRES && rt->dst.expires) {
1775                 if (time_after(now, rt->dst.expires)) {
1776                         RT6_TRACE("expiring %p\n", rt);
1777                         return -1;
1778                 }
1779                 gc_args->more++;
1780         } else if (rt->rt6i_flags & RTF_CACHE) {
1781                 if (atomic_read(&rt->dst.__refcnt) == 1 &&
1782                     time_after_eq(now, rt->dst.lastuse + gc_args->timeout)) {
1783                         RT6_TRACE("aging clone %p\n", rt);
1784                         return -1;
1785                 } else if (rt->rt6i_flags & RTF_GATEWAY) {
1786                         struct neighbour *neigh;
1787                         __u8 neigh_flags = 0;
1788
1789                         neigh = dst_neigh_lookup(&rt->dst, &rt->rt6i_gateway);
1790                         if (neigh) {
1791                                 neigh_flags = neigh->flags;
1792                                 neigh_release(neigh);
1793                         }
1794                         if (!(neigh_flags & NTF_ROUTER)) {
1795                                 RT6_TRACE("purging route %p via non-router but gateway\n",
1796                                           rt);
1797                                 return -1;
1798                         }
1799                 }
1800                 gc_args->more++;
1801         }
1802
1803         return 0;
1804 }
1805
1806 void fib6_run_gc(unsigned long expires, struct net *net, bool force)
1807 {
1808         struct fib6_gc_args gc_args;
1809         unsigned long now;
1810
1811         if (force) {
1812                 spin_lock_bh(&net->ipv6.fib6_gc_lock);
1813         } else if (!spin_trylock_bh(&net->ipv6.fib6_gc_lock)) {
1814                 mod_timer(&net->ipv6.ip6_fib_timer, jiffies + HZ);
1815                 return;
1816         }
1817         gc_args.timeout = expires ? (int)expires :
1818                           net->ipv6.sysctl.ip6_rt_gc_interval;
1819         gc_args.more = 0;
1820
1821         fib6_clean_all(net, fib6_age, &gc_args);
1822         now = jiffies;
1823         net->ipv6.ip6_rt_last_gc = now;
1824
1825         if (gc_args.more)
1826                 mod_timer(&net->ipv6.ip6_fib_timer,
1827                           round_jiffies(now
1828                                         + net->ipv6.sysctl.ip6_rt_gc_interval));
1829         else
1830                 del_timer(&net->ipv6.ip6_fib_timer);
1831         spin_unlock_bh(&net->ipv6.fib6_gc_lock);
1832 }
1833
1834 static void fib6_gc_timer_cb(unsigned long arg)
1835 {
1836         fib6_run_gc(0, (struct net *)arg, true);
1837 }
1838
1839 static int __net_init fib6_net_init(struct net *net)
1840 {
1841         size_t size = sizeof(struct hlist_head) * FIB6_TABLE_HASHSZ;
1842
1843         spin_lock_init(&net->ipv6.fib6_gc_lock);
1844         rwlock_init(&net->ipv6.fib6_walker_lock);
1845         INIT_LIST_HEAD(&net->ipv6.fib6_walkers);
1846         setup_timer(&net->ipv6.ip6_fib_timer, fib6_gc_timer_cb, (unsigned long)net);
1847
1848         net->ipv6.rt6_stats = kzalloc(sizeof(*net->ipv6.rt6_stats), GFP_KERNEL);
1849         if (!net->ipv6.rt6_stats)
1850                 goto out_timer;
1851
1852         /* Avoid false sharing : Use at least a full cache line */
1853         size = max_t(size_t, size, L1_CACHE_BYTES);
1854
1855         net->ipv6.fib_table_hash = kzalloc(size, GFP_KERNEL);
1856         if (!net->ipv6.fib_table_hash)
1857                 goto out_rt6_stats;
1858
1859         net->ipv6.fib6_main_tbl = kzalloc(sizeof(*net->ipv6.fib6_main_tbl),
1860                                           GFP_KERNEL);
1861         if (!net->ipv6.fib6_main_tbl)
1862                 goto out_fib_table_hash;
1863
1864         net->ipv6.fib6_main_tbl->tb6_id = RT6_TABLE_MAIN;
1865         net->ipv6.fib6_main_tbl->tb6_root.leaf = net->ipv6.ip6_null_entry;
1866         net->ipv6.fib6_main_tbl->tb6_root.fn_flags =
1867                 RTN_ROOT | RTN_TL_ROOT | RTN_RTINFO;
1868         inet_peer_base_init(&net->ipv6.fib6_main_tbl->tb6_peers);
1869
1870 #ifdef CONFIG_IPV6_MULTIPLE_TABLES
1871         net->ipv6.fib6_local_tbl = kzalloc(sizeof(*net->ipv6.fib6_local_tbl),
1872                                            GFP_KERNEL);
1873         if (!net->ipv6.fib6_local_tbl)
1874                 goto out_fib6_main_tbl;
1875         net->ipv6.fib6_local_tbl->tb6_id = RT6_TABLE_LOCAL;
1876         net->ipv6.fib6_local_tbl->tb6_root.leaf = net->ipv6.ip6_null_entry;
1877         net->ipv6.fib6_local_tbl->tb6_root.fn_flags =
1878                 RTN_ROOT | RTN_TL_ROOT | RTN_RTINFO;
1879         inet_peer_base_init(&net->ipv6.fib6_local_tbl->tb6_peers);
1880 #endif
1881         fib6_tables_init(net);
1882
1883         return 0;
1884
1885 #ifdef CONFIG_IPV6_MULTIPLE_TABLES
1886 out_fib6_main_tbl:
1887         kfree(net->ipv6.fib6_main_tbl);
1888 #endif
1889 out_fib_table_hash:
1890         kfree(net->ipv6.fib_table_hash);
1891 out_rt6_stats:
1892         kfree(net->ipv6.rt6_stats);
1893 out_timer:
1894         return -ENOMEM;
1895 }
1896
1897 static void fib6_net_exit(struct net *net)
1898 {
1899         rt6_ifdown(net, NULL);
1900         del_timer_sync(&net->ipv6.ip6_fib_timer);
1901
1902 #ifdef CONFIG_IPV6_MULTIPLE_TABLES
1903         inetpeer_invalidate_tree(&net->ipv6.fib6_local_tbl->tb6_peers);
1904         kfree(net->ipv6.fib6_local_tbl);
1905 #endif
1906         inetpeer_invalidate_tree(&net->ipv6.fib6_main_tbl->tb6_peers);
1907         kfree(net->ipv6.fib6_main_tbl);
1908         kfree(net->ipv6.fib_table_hash);
1909         kfree(net->ipv6.rt6_stats);
1910 }
1911
1912 static struct pernet_operations fib6_net_ops = {
1913         .init = fib6_net_init,
1914         .exit = fib6_net_exit,
1915 };
1916
1917 int __init fib6_init(void)
1918 {
1919         int ret = -ENOMEM;
1920
1921         fib6_node_kmem = kmem_cache_create("fib6_nodes",
1922                                            sizeof(struct fib6_node),
1923                                            0, SLAB_HWCACHE_ALIGN,
1924                                            NULL);
1925         if (!fib6_node_kmem)
1926                 goto out;
1927
1928         ret = register_pernet_subsys(&fib6_net_ops);
1929         if (ret)
1930                 goto out_kmem_cache_create;
1931
1932         ret = __rtnl_register(PF_INET6, RTM_GETROUTE, NULL, inet6_dump_fib,
1933                               NULL);
1934         if (ret)
1935                 goto out_unregister_subsys;
1936
1937         __fib6_flush_trees = fib6_flush_trees;
1938 out:
1939         return ret;
1940
1941 out_unregister_subsys:
1942         unregister_pernet_subsys(&fib6_net_ops);
1943 out_kmem_cache_create:
1944         kmem_cache_destroy(fib6_node_kmem);
1945         goto out;
1946 }
1947
1948 void fib6_gc_cleanup(void)
1949 {
1950         unregister_pernet_subsys(&fib6_net_ops);
1951         kmem_cache_destroy(fib6_node_kmem);
1952 }
1953
1954 #ifdef CONFIG_PROC_FS
1955
1956 struct ipv6_route_iter {
1957         struct seq_net_private p;
1958         struct fib6_walker w;
1959         loff_t skip;
1960         struct fib6_table *tbl;
1961         int sernum;
1962 };
1963
1964 static int ipv6_route_seq_show(struct seq_file *seq, void *v)
1965 {
1966         struct rt6_info *rt = v;
1967         struct ipv6_route_iter *iter = seq->private;
1968
1969         seq_printf(seq, "%pi6 %02x ", &rt->rt6i_dst.addr, rt->rt6i_dst.plen);
1970
1971 #ifdef CONFIG_IPV6_SUBTREES
1972         seq_printf(seq, "%pi6 %02x ", &rt->rt6i_src.addr, rt->rt6i_src.plen);
1973 #else
1974         seq_puts(seq, "00000000000000000000000000000000 00 ");
1975 #endif
1976         if (rt->rt6i_flags & RTF_GATEWAY)
1977                 seq_printf(seq, "%pi6", &rt->rt6i_gateway);
1978         else
1979                 seq_puts(seq, "00000000000000000000000000000000");
1980
1981         seq_printf(seq, " %08x %08x %08x %08x %8s\n",
1982                    rt->rt6i_metric, atomic_read(&rt->dst.__refcnt),
1983                    rt->dst.__use, rt->rt6i_flags,
1984                    rt->dst.dev ? rt->dst.dev->name : "");
1985         iter->w.leaf = NULL;
1986         return 0;
1987 }
1988
1989 static int ipv6_route_yield(struct fib6_walker *w)
1990 {
1991         struct ipv6_route_iter *iter = w->args;
1992
1993         if (!iter->skip)
1994                 return 1;
1995
1996         do {
1997                 iter->w.leaf = iter->w.leaf->dst.rt6_next;
1998                 iter->skip--;
1999                 if (!iter->skip && iter->w.leaf)
2000                         return 1;
2001         } while (iter->w.leaf);
2002
2003         return 0;
2004 }
2005
2006 static void ipv6_route_seq_setup_walk(struct ipv6_route_iter *iter,
2007                                       struct net *net)
2008 {
2009         memset(&iter->w, 0, sizeof(iter->w));
2010         iter->w.func = ipv6_route_yield;
2011         iter->w.root = &iter->tbl->tb6_root;
2012         iter->w.state = FWS_INIT;
2013         iter->w.node = iter->w.root;
2014         iter->w.args = iter;
2015         iter->sernum = iter->w.root->fn_sernum;
2016         INIT_LIST_HEAD(&iter->w.lh);
2017         fib6_walker_link(net, &iter->w);
2018 }
2019
2020 static struct fib6_table *ipv6_route_seq_next_table(struct fib6_table *tbl,
2021                                                     struct net *net)
2022 {
2023         unsigned int h;
2024         struct hlist_node *node;
2025
2026         if (tbl) {
2027                 h = (tbl->tb6_id & (FIB6_TABLE_HASHSZ - 1)) + 1;
2028                 node = rcu_dereference_bh(hlist_next_rcu(&tbl->tb6_hlist));
2029         } else {
2030                 h = 0;
2031                 node = NULL;
2032         }
2033
2034         while (!node && h < FIB6_TABLE_HASHSZ) {
2035                 node = rcu_dereference_bh(
2036                         hlist_first_rcu(&net->ipv6.fib_table_hash[h++]));
2037         }
2038         return hlist_entry_safe(node, struct fib6_table, tb6_hlist);
2039 }
2040
2041 static void ipv6_route_check_sernum(struct ipv6_route_iter *iter)
2042 {
2043         if (iter->sernum != iter->w.root->fn_sernum) {
2044                 iter->sernum = iter->w.root->fn_sernum;
2045                 iter->w.state = FWS_INIT;
2046                 iter->w.node = iter->w.root;
2047                 WARN_ON(iter->w.skip);
2048                 iter->w.skip = iter->w.count;
2049         }
2050 }
2051
2052 static void *ipv6_route_seq_next(struct seq_file *seq, void *v, loff_t *pos)
2053 {
2054         int r;
2055         struct rt6_info *n;
2056         struct net *net = seq_file_net(seq);
2057         struct ipv6_route_iter *iter = seq->private;
2058
2059         if (!v)
2060                 goto iter_table;
2061
2062         n = ((struct rt6_info *)v)->dst.rt6_next;
2063         if (n) {
2064                 ++*pos;
2065                 return n;
2066         }
2067
2068 iter_table:
2069         ipv6_route_check_sernum(iter);
2070         read_lock(&iter->tbl->tb6_lock);
2071         r = fib6_walk_continue(&iter->w);
2072         read_unlock(&iter->tbl->tb6_lock);
2073         if (r > 0) {
2074                 if (v)
2075                         ++*pos;
2076                 return iter->w.leaf;
2077         } else if (r < 0) {
2078                 fib6_walker_unlink(net, &iter->w);
2079                 return NULL;
2080         }
2081         fib6_walker_unlink(net, &iter->w);
2082
2083         iter->tbl = ipv6_route_seq_next_table(iter->tbl, net);
2084         if (!iter->tbl)
2085                 return NULL;
2086
2087         ipv6_route_seq_setup_walk(iter, net);
2088         goto iter_table;
2089 }
2090
2091 static void *ipv6_route_seq_start(struct seq_file *seq, loff_t *pos)
2092         __acquires(RCU_BH)
2093 {
2094         struct net *net = seq_file_net(seq);
2095         struct ipv6_route_iter *iter = seq->private;
2096
2097         rcu_read_lock_bh();
2098         iter->tbl = ipv6_route_seq_next_table(NULL, net);
2099         iter->skip = *pos;
2100
2101         if (iter->tbl) {
2102                 ipv6_route_seq_setup_walk(iter, net);
2103                 return ipv6_route_seq_next(seq, NULL, pos);
2104         } else {
2105                 return NULL;
2106         }
2107 }
2108
2109 static bool ipv6_route_iter_active(struct ipv6_route_iter *iter)
2110 {
2111         struct fib6_walker *w = &iter->w;
2112         return w->node && !(w->state == FWS_U && w->node == w->root);
2113 }
2114
2115 static void ipv6_route_seq_stop(struct seq_file *seq, void *v)
2116         __releases(RCU_BH)
2117 {
2118         struct net *net = seq_file_net(seq);
2119         struct ipv6_route_iter *iter = seq->private;
2120
2121         if (ipv6_route_iter_active(iter))
2122                 fib6_walker_unlink(net, &iter->w);
2123
2124         rcu_read_unlock_bh();
2125 }
2126
2127 static const struct seq_operations ipv6_route_seq_ops = {
2128         .start  = ipv6_route_seq_start,
2129         .next   = ipv6_route_seq_next,
2130         .stop   = ipv6_route_seq_stop,
2131         .show   = ipv6_route_seq_show
2132 };
2133
2134 int ipv6_route_open(struct inode *inode, struct file *file)
2135 {
2136         return seq_open_net(inode, file, &ipv6_route_seq_ops,
2137                             sizeof(struct ipv6_route_iter));
2138 }
2139
2140 #endif /* CONFIG_PROC_FS */