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Linux/net/ipv4/fib_trie.c

  1 /*
  2  *   This program is free software; you can redistribute it and/or
  3  *   modify it under the terms of the GNU General Public License
  4  *   as published by the Free Software Foundation; either version
  5  *   2 of the License, or (at your option) any later version.
  6  *
  7  *   Robert Olsson <robert.olsson@its.uu.se> Uppsala Universitet
  8  *     & Swedish University of Agricultural Sciences.
  9  *
 10  *   Jens Laas <jens.laas@data.slu.se> Swedish University of
 11  *     Agricultural Sciences.
 12  *
 13  *   Hans Liss <hans.liss@its.uu.se>  Uppsala Universitet
 14  *
 15  * This work is based on the LPC-trie which is originally described in:
 16  *
 17  * An experimental study of compression methods for dynamic tries
 18  * Stefan Nilsson and Matti Tikkanen. Algorithmica, 33(1):19-33, 2002.
 19  * http://www.csc.kth.se/~snilsson/software/dyntrie2/
 20  *
 21  *
 22  * IP-address lookup using LC-tries. Stefan Nilsson and Gunnar Karlsson
 23  * IEEE Journal on Selected Areas in Communications, 17(6):1083-1092, June 1999
 24  *
 25  *
 26  * Code from fib_hash has been reused which includes the following header:
 27  *
 28  *
 29  * INET         An implementation of the TCP/IP protocol suite for the LINUX
 30  *              operating system.  INET is implemented using the  BSD Socket
 31  *              interface as the means of communication with the user level.
 32  *
 33  *              IPv4 FIB: lookup engine and maintenance routines.
 34  *
 35  *
 36  * Authors:     Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
 37  *
 38  *              This program is free software; you can redistribute it and/or
 39  *              modify it under the terms of the GNU General Public License
 40  *              as published by the Free Software Foundation; either version
 41  *              2 of the License, or (at your option) any later version.
 42  *
 43  * Substantial contributions to this work comes from:
 44  *
 45  *              David S. Miller, <davem@davemloft.net>
 46  *              Stephen Hemminger <shemminger@osdl.org>
 47  *              Paul E. McKenney <paulmck@us.ibm.com>
 48  *              Patrick McHardy <kaber@trash.net>
 49  */
 50 
 51 #define VERSION "0.409"
 52 
 53 #include <asm/uaccess.h>
 54 #include <linux/bitops.h>
 55 #include <linux/types.h>
 56 #include <linux/kernel.h>
 57 #include <linux/mm.h>
 58 #include <linux/string.h>
 59 #include <linux/socket.h>
 60 #include <linux/sockios.h>
 61 #include <linux/errno.h>
 62 #include <linux/in.h>
 63 #include <linux/inet.h>
 64 #include <linux/inetdevice.h>
 65 #include <linux/netdevice.h>
 66 #include <linux/if_arp.h>
 67 #include <linux/proc_fs.h>
 68 #include <linux/rcupdate.h>
 69 #include <linux/skbuff.h>
 70 #include <linux/netlink.h>
 71 #include <linux/init.h>
 72 #include <linux/list.h>
 73 #include <linux/slab.h>
 74 #include <linux/export.h>
 75 #include <linux/vmalloc.h>
 76 #include <linux/notifier.h>
 77 #include <net/net_namespace.h>
 78 #include <net/ip.h>
 79 #include <net/protocol.h>
 80 #include <net/route.h>
 81 #include <net/tcp.h>
 82 #include <net/sock.h>
 83 #include <net/ip_fib.h>
 84 #include <trace/events/fib.h>
 85 #include "fib_lookup.h"
 86 
 87 static BLOCKING_NOTIFIER_HEAD(fib_chain);
 88 
 89 int register_fib_notifier(struct notifier_block *nb)
 90 {
 91         return blocking_notifier_chain_register(&fib_chain, nb);
 92 }
 93 EXPORT_SYMBOL(register_fib_notifier);
 94 
 95 int unregister_fib_notifier(struct notifier_block *nb)
 96 {
 97         return blocking_notifier_chain_unregister(&fib_chain, nb);
 98 }
 99 EXPORT_SYMBOL(unregister_fib_notifier);
100 
101 int call_fib_notifiers(struct net *net, enum fib_event_type event_type,
102                        struct fib_notifier_info *info)
103 {
104         info->net = net;
105         return blocking_notifier_call_chain(&fib_chain, event_type, info);
106 }
107 
108 static int call_fib_entry_notifiers(struct net *net,
109                                     enum fib_event_type event_type, u32 dst,
110                                     int dst_len, struct fib_info *fi,
111                                     u8 tos, u8 type, u32 tb_id, u32 nlflags)
112 {
113         struct fib_entry_notifier_info info = {
114                 .dst = dst,
115                 .dst_len = dst_len,
116                 .fi = fi,
117                 .tos = tos,
118                 .type = type,
119                 .tb_id = tb_id,
120                 .nlflags = nlflags,
121         };
122         return call_fib_notifiers(net, event_type, &info.info);
123 }
124 
125 #define MAX_STAT_DEPTH 32
126 
127 #define KEYLENGTH       (8*sizeof(t_key))
128 #define KEY_MAX         ((t_key)~0)
129 
130 typedef unsigned int t_key;
131 
132 #define IS_TRIE(n)      ((n)->pos >= KEYLENGTH)
133 #define IS_TNODE(n)     ((n)->bits)
134 #define IS_LEAF(n)      (!(n)->bits)
135 
136 struct key_vector {
137         t_key key;
138         unsigned char pos;              /* 2log(KEYLENGTH) bits needed */
139         unsigned char bits;             /* 2log(KEYLENGTH) bits needed */
140         unsigned char slen;
141         union {
142                 /* This list pointer if valid if (pos | bits) == 0 (LEAF) */
143                 struct hlist_head leaf;
144                 /* This array is valid if (pos | bits) > 0 (TNODE) */
145                 struct key_vector __rcu *tnode[0];
146         };
147 };
148 
149 struct tnode {
150         struct rcu_head rcu;
151         t_key empty_children;           /* KEYLENGTH bits needed */
152         t_key full_children;            /* KEYLENGTH bits needed */
153         struct key_vector __rcu *parent;
154         struct key_vector kv[1];
155 #define tn_bits kv[0].bits
156 };
157 
158 #define TNODE_SIZE(n)   offsetof(struct tnode, kv[0].tnode[n])
159 #define LEAF_SIZE       TNODE_SIZE(1)
160 
161 #ifdef CONFIG_IP_FIB_TRIE_STATS
162 struct trie_use_stats {
163         unsigned int gets;
164         unsigned int backtrack;
165         unsigned int semantic_match_passed;
166         unsigned int semantic_match_miss;
167         unsigned int null_node_hit;
168         unsigned int resize_node_skipped;
169 };
170 #endif
171 
172 struct trie_stat {
173         unsigned int totdepth;
174         unsigned int maxdepth;
175         unsigned int tnodes;
176         unsigned int leaves;
177         unsigned int nullpointers;
178         unsigned int prefixes;
179         unsigned int nodesizes[MAX_STAT_DEPTH];
180 };
181 
182 struct trie {
183         struct key_vector kv[1];
184 #ifdef CONFIG_IP_FIB_TRIE_STATS
185         struct trie_use_stats __percpu *stats;
186 #endif
187 };
188 
189 static struct key_vector *resize(struct trie *t, struct key_vector *tn);
190 static size_t tnode_free_size;
191 
192 /*
193  * synchronize_rcu after call_rcu for that many pages; it should be especially
194  * useful before resizing the root node with PREEMPT_NONE configs; the value was
195  * obtained experimentally, aiming to avoid visible slowdown.
196  */
197 static const int sync_pages = 128;
198 
199 static struct kmem_cache *fn_alias_kmem __read_mostly;
200 static struct kmem_cache *trie_leaf_kmem __read_mostly;
201 
202 static inline struct tnode *tn_info(struct key_vector *kv)
203 {
204         return container_of(kv, struct tnode, kv[0]);
205 }
206 
207 /* caller must hold RTNL */
208 #define node_parent(tn) rtnl_dereference(tn_info(tn)->parent)
209 #define get_child(tn, i) rtnl_dereference((tn)->tnode[i])
210 
211 /* caller must hold RCU read lock or RTNL */
212 #define node_parent_rcu(tn) rcu_dereference_rtnl(tn_info(tn)->parent)
213 #define get_child_rcu(tn, i) rcu_dereference_rtnl((tn)->tnode[i])
214 
215 /* wrapper for rcu_assign_pointer */
216 static inline void node_set_parent(struct key_vector *n, struct key_vector *tp)
217 {
218         if (n)
219                 rcu_assign_pointer(tn_info(n)->parent, tp);
220 }
221 
222 #define NODE_INIT_PARENT(n, p) RCU_INIT_POINTER(tn_info(n)->parent, p)
223 
224 /* This provides us with the number of children in this node, in the case of a
225  * leaf this will return 0 meaning none of the children are accessible.
226  */
227 static inline unsigned long child_length(const struct key_vector *tn)
228 {
229         return (1ul << tn->bits) & ~(1ul);
230 }
231 
232 #define get_cindex(key, kv) (((key) ^ (kv)->key) >> (kv)->pos)
233 
234 static inline unsigned long get_index(t_key key, struct key_vector *kv)
235 {
236         unsigned long index = key ^ kv->key;
237 
238         if ((BITS_PER_LONG <= KEYLENGTH) && (KEYLENGTH == kv->pos))
239                 return 0;
240 
241         return index >> kv->pos;
242 }
243 
244 /* To understand this stuff, an understanding of keys and all their bits is
245  * necessary. Every node in the trie has a key associated with it, but not
246  * all of the bits in that key are significant.
247  *
248  * Consider a node 'n' and its parent 'tp'.
249  *
250  * If n is a leaf, every bit in its key is significant. Its presence is
251  * necessitated by path compression, since during a tree traversal (when
252  * searching for a leaf - unless we are doing an insertion) we will completely
253  * ignore all skipped bits we encounter. Thus we need to verify, at the end of
254  * a potentially successful search, that we have indeed been walking the
255  * correct key path.
256  *
257  * Note that we can never "miss" the correct key in the tree if present by
258  * following the wrong path. Path compression ensures that segments of the key
259  * that are the same for all keys with a given prefix are skipped, but the
260  * skipped part *is* identical for each node in the subtrie below the skipped
261  * bit! trie_insert() in this implementation takes care of that.
262  *
263  * if n is an internal node - a 'tnode' here, the various parts of its key
264  * have many different meanings.
265  *
266  * Example:
267  * _________________________________________________________________
268  * | i | i | i | i | i | i | i | N | N | N | S | S | S | S | S | C |
269  * -----------------------------------------------------------------
270  *  31  30  29  28  27  26  25  24  23  22  21  20  19  18  17  16
271  *
272  * _________________________________________________________________
273  * | C | C | C | u | u | u | u | u | u | u | u | u | u | u | u | u |
274  * -----------------------------------------------------------------
275  *  15  14  13  12  11  10   9   8   7   6   5   4   3   2   1   0
276  *
277  * tp->pos = 22
278  * tp->bits = 3
279  * n->pos = 13
280  * n->bits = 4
281  *
282  * First, let's just ignore the bits that come before the parent tp, that is
283  * the bits from (tp->pos + tp->bits) to 31. They are *known* but at this
284  * point we do not use them for anything.
285  *
286  * The bits from (tp->pos) to (tp->pos + tp->bits - 1) - "N", above - are the
287  * index into the parent's child array. That is, they will be used to find
288  * 'n' among tp's children.
289  *
290  * The bits from (n->pos + n->bits) to (tp->pos - 1) - "S" - are skipped bits
291  * for the node n.
292  *
293  * All the bits we have seen so far are significant to the node n. The rest
294  * of the bits are really not needed or indeed known in n->key.
295  *
296  * The bits from (n->pos) to (n->pos + n->bits - 1) - "C" - are the index into
297  * n's child array, and will of course be different for each child.
298  *
299  * The rest of the bits, from 0 to (n->pos -1) - "u" - are completely unknown
300  * at this point.
301  */
302 
303 static const int halve_threshold = 25;
304 static const int inflate_threshold = 50;
305 static const int halve_threshold_root = 15;
306 static const int inflate_threshold_root = 30;
307 
308 static void __alias_free_mem(struct rcu_head *head)
309 {
310         struct fib_alias *fa = container_of(head, struct fib_alias, rcu);
311         kmem_cache_free(fn_alias_kmem, fa);
312 }
313 
314 static inline void alias_free_mem_rcu(struct fib_alias *fa)
315 {
316         call_rcu(&fa->rcu, __alias_free_mem);
317 }
318 
319 #define TNODE_KMALLOC_MAX \
320         ilog2((PAGE_SIZE - TNODE_SIZE(0)) / sizeof(struct key_vector *))
321 #define TNODE_VMALLOC_MAX \
322         ilog2((SIZE_MAX - TNODE_SIZE(0)) / sizeof(struct key_vector *))
323 
324 static void __node_free_rcu(struct rcu_head *head)
325 {
326         struct tnode *n = container_of(head, struct tnode, rcu);
327 
328         if (!n->tn_bits)
329                 kmem_cache_free(trie_leaf_kmem, n);
330         else
331                 kvfree(n);
332 }
333 
334 #define node_free(n) call_rcu(&tn_info(n)->rcu, __node_free_rcu)
335 
336 static struct tnode *tnode_alloc(int bits)
337 {
338         size_t size;
339 
340         /* verify bits is within bounds */
341         if (bits > TNODE_VMALLOC_MAX)
342                 return NULL;
343 
344         /* determine size and verify it is non-zero and didn't overflow */
345         size = TNODE_SIZE(1ul << bits);
346 
347         if (size <= PAGE_SIZE)
348                 return kzalloc(size, GFP_KERNEL);
349         else
350                 return vzalloc(size);
351 }
352 
353 static inline void empty_child_inc(struct key_vector *n)
354 {
355         ++tn_info(n)->empty_children ? : ++tn_info(n)->full_children;
356 }
357 
358 static inline void empty_child_dec(struct key_vector *n)
359 {
360         tn_info(n)->empty_children-- ? : tn_info(n)->full_children--;
361 }
362 
363 static struct key_vector *leaf_new(t_key key, struct fib_alias *fa)
364 {
365         struct key_vector *l;
366         struct tnode *kv;
367 
368         kv = kmem_cache_alloc(trie_leaf_kmem, GFP_KERNEL);
369         if (!kv)
370                 return NULL;
371 
372         /* initialize key vector */
373         l = kv->kv;
374         l->key = key;
375         l->pos = 0;
376         l->bits = 0;
377         l->slen = fa->fa_slen;
378 
379         /* link leaf to fib alias */
380         INIT_HLIST_HEAD(&l->leaf);
381         hlist_add_head(&fa->fa_list, &l->leaf);
382 
383         return l;
384 }
385 
386 static struct key_vector *tnode_new(t_key key, int pos, int bits)
387 {
388         unsigned int shift = pos + bits;
389         struct key_vector *tn;
390         struct tnode *tnode;
391 
392         /* verify bits and pos their msb bits clear and values are valid */
393         BUG_ON(!bits || (shift > KEYLENGTH));
394 
395         tnode = tnode_alloc(bits);
396         if (!tnode)
397                 return NULL;
398 
399         pr_debug("AT %p s=%zu %zu\n", tnode, TNODE_SIZE(0),
400                  sizeof(struct key_vector *) << bits);
401 
402         if (bits == KEYLENGTH)
403                 tnode->full_children = 1;
404         else
405                 tnode->empty_children = 1ul << bits;
406 
407         tn = tnode->kv;
408         tn->key = (shift < KEYLENGTH) ? (key >> shift) << shift : 0;
409         tn->pos = pos;
410         tn->bits = bits;
411         tn->slen = pos;
412 
413         return tn;
414 }
415 
416 /* Check whether a tnode 'n' is "full", i.e. it is an internal node
417  * and no bits are skipped. See discussion in dyntree paper p. 6
418  */
419 static inline int tnode_full(struct key_vector *tn, struct key_vector *n)
420 {
421         return n && ((n->pos + n->bits) == tn->pos) && IS_TNODE(n);
422 }
423 
424 /* Add a child at position i overwriting the old value.
425  * Update the value of full_children and empty_children.
426  */
427 static void put_child(struct key_vector *tn, unsigned long i,
428                       struct key_vector *n)
429 {
430         struct key_vector *chi = get_child(tn, i);
431         int isfull, wasfull;
432 
433         BUG_ON(i >= child_length(tn));
434 
435         /* update emptyChildren, overflow into fullChildren */
436         if (!n && chi)
437                 empty_child_inc(tn);
438         if (n && !chi)
439                 empty_child_dec(tn);
440 
441         /* update fullChildren */
442         wasfull = tnode_full(tn, chi);
443         isfull = tnode_full(tn, n);
444 
445         if (wasfull && !isfull)
446                 tn_info(tn)->full_children--;
447         else if (!wasfull && isfull)
448                 tn_info(tn)->full_children++;
449 
450         if (n && (tn->slen < n->slen))
451                 tn->slen = n->slen;
452 
453         rcu_assign_pointer(tn->tnode[i], n);
454 }
455 
456 static void update_children(struct key_vector *tn)
457 {
458         unsigned long i;
459 
460         /* update all of the child parent pointers */
461         for (i = child_length(tn); i;) {
462                 struct key_vector *inode = get_child(tn, --i);
463 
464                 if (!inode)
465                         continue;
466 
467                 /* Either update the children of a tnode that
468                  * already belongs to us or update the child
469                  * to point to ourselves.
470                  */
471                 if (node_parent(inode) == tn)
472                         update_children(inode);
473                 else
474                         node_set_parent(inode, tn);
475         }
476 }
477 
478 static inline void put_child_root(struct key_vector *tp, t_key key,
479                                   struct key_vector *n)
480 {
481         if (IS_TRIE(tp))
482                 rcu_assign_pointer(tp->tnode[0], n);
483         else
484                 put_child(tp, get_index(key, tp), n);
485 }
486 
487 static inline void tnode_free_init(struct key_vector *tn)
488 {
489         tn_info(tn)->rcu.next = NULL;
490 }
491 
492 static inline void tnode_free_append(struct key_vector *tn,
493                                      struct key_vector *n)
494 {
495         tn_info(n)->rcu.next = tn_info(tn)->rcu.next;
496         tn_info(tn)->rcu.next = &tn_info(n)->rcu;
497 }
498 
499 static void tnode_free(struct key_vector *tn)
500 {
501         struct callback_head *head = &tn_info(tn)->rcu;
502 
503         while (head) {
504                 head = head->next;
505                 tnode_free_size += TNODE_SIZE(1ul << tn->bits);
506                 node_free(tn);
507 
508                 tn = container_of(head, struct tnode, rcu)->kv;
509         }
510 
511         if (tnode_free_size >= PAGE_SIZE * sync_pages) {
512                 tnode_free_size = 0;
513                 synchronize_rcu();
514         }
515 }
516 
517 static struct key_vector *replace(struct trie *t,
518                                   struct key_vector *oldtnode,
519                                   struct key_vector *tn)
520 {
521         struct key_vector *tp = node_parent(oldtnode);
522         unsigned long i;
523 
524         /* setup the parent pointer out of and back into this node */
525         NODE_INIT_PARENT(tn, tp);
526         put_child_root(tp, tn->key, tn);
527 
528         /* update all of the child parent pointers */
529         update_children(tn);
530 
531         /* all pointers should be clean so we are done */
532         tnode_free(oldtnode);
533 
534         /* resize children now that oldtnode is freed */
535         for (i = child_length(tn); i;) {
536                 struct key_vector *inode = get_child(tn, --i);
537 
538                 /* resize child node */
539                 if (tnode_full(tn, inode))
540                         tn = resize(t, inode);
541         }
542 
543         return tp;
544 }
545 
546 static struct key_vector *inflate(struct trie *t,
547                                   struct key_vector *oldtnode)
548 {
549         struct key_vector *tn;
550         unsigned long i;
551         t_key m;
552 
553         pr_debug("In inflate\n");
554 
555         tn = tnode_new(oldtnode->key, oldtnode->pos - 1, oldtnode->bits + 1);
556         if (!tn)
557                 goto notnode;
558 
559         /* prepare oldtnode to be freed */
560         tnode_free_init(oldtnode);
561 
562         /* Assemble all of the pointers in our cluster, in this case that
563          * represents all of the pointers out of our allocated nodes that
564          * point to existing tnodes and the links between our allocated
565          * nodes.
566          */
567         for (i = child_length(oldtnode), m = 1u << tn->pos; i;) {
568                 struct key_vector *inode = get_child(oldtnode, --i);
569                 struct key_vector *node0, *node1;
570                 unsigned long j, k;
571 
572                 /* An empty child */
573                 if (!inode)
574                         continue;
575 
576                 /* A leaf or an internal node with skipped bits */
577                 if (!tnode_full(oldtnode, inode)) {
578                         put_child(tn, get_index(inode->key, tn), inode);
579                         continue;
580                 }
581 
582                 /* drop the node in the old tnode free list */
583                 tnode_free_append(oldtnode, inode);
584 
585                 /* An internal node with two children */
586                 if (inode->bits == 1) {
587                         put_child(tn, 2 * i + 1, get_child(inode, 1));
588                         put_child(tn, 2 * i, get_child(inode, 0));
589                         continue;
590                 }
591 
592                 /* We will replace this node 'inode' with two new
593                  * ones, 'node0' and 'node1', each with half of the
594                  * original children. The two new nodes will have
595                  * a position one bit further down the key and this
596                  * means that the "significant" part of their keys
597                  * (see the discussion near the top of this file)
598                  * will differ by one bit, which will be "" in
599                  * node0's key and "1" in node1's key. Since we are
600                  * moving the key position by one step, the bit that
601                  * we are moving away from - the bit at position
602                  * (tn->pos) - is the one that will differ between
603                  * node0 and node1. So... we synthesize that bit in the
604                  * two new keys.
605                  */
606                 node1 = tnode_new(inode->key | m, inode->pos, inode->bits - 1);
607                 if (!node1)
608                         goto nomem;
609                 node0 = tnode_new(inode->key, inode->pos, inode->bits - 1);
610 
611                 tnode_free_append(tn, node1);
612                 if (!node0)
613                         goto nomem;
614                 tnode_free_append(tn, node0);
615 
616                 /* populate child pointers in new nodes */
617                 for (k = child_length(inode), j = k / 2; j;) {
618                         put_child(node1, --j, get_child(inode, --k));
619                         put_child(node0, j, get_child(inode, j));
620                         put_child(node1, --j, get_child(inode, --k));
621                         put_child(node0, j, get_child(inode, j));
622                 }
623 
624                 /* link new nodes to parent */
625                 NODE_INIT_PARENT(node1, tn);
626                 NODE_INIT_PARENT(node0, tn);
627 
628                 /* link parent to nodes */
629                 put_child(tn, 2 * i + 1, node1);
630                 put_child(tn, 2 * i, node0);
631         }
632 
633         /* setup the parent pointers into and out of this node */
634         return replace(t, oldtnode, tn);
635 nomem:
636         /* all pointers should be clean so we are done */
637         tnode_free(tn);
638 notnode:
639         return NULL;
640 }
641 
642 static struct key_vector *halve(struct trie *t,
643                                 struct key_vector *oldtnode)
644 {
645         struct key_vector *tn;
646         unsigned long i;
647 
648         pr_debug("In halve\n");
649 
650         tn = tnode_new(oldtnode->key, oldtnode->pos + 1, oldtnode->bits - 1);
651         if (!tn)
652                 goto notnode;
653 
654         /* prepare oldtnode to be freed */
655         tnode_free_init(oldtnode);
656 
657         /* Assemble all of the pointers in our cluster, in this case that
658          * represents all of the pointers out of our allocated nodes that
659          * point to existing tnodes and the links between our allocated
660          * nodes.
661          */
662         for (i = child_length(oldtnode); i;) {
663                 struct key_vector *node1 = get_child(oldtnode, --i);
664                 struct key_vector *node0 = get_child(oldtnode, --i);
665                 struct key_vector *inode;
666 
667                 /* At least one of the children is empty */
668                 if (!node1 || !node0) {
669                         put_child(tn, i / 2, node1 ? : node0);
670                         continue;
671                 }
672 
673                 /* Two nonempty children */
674                 inode = tnode_new(node0->key, oldtnode->pos, 1);
675                 if (!inode)
676                         goto nomem;
677                 tnode_free_append(tn, inode);
678 
679                 /* initialize pointers out of node */
680                 put_child(inode, 1, node1);
681                 put_child(inode, 0, node0);
682                 NODE_INIT_PARENT(inode, tn);
683 
684                 /* link parent to node */
685                 put_child(tn, i / 2, inode);
686         }
687 
688         /* setup the parent pointers into and out of this node */
689         return replace(t, oldtnode, tn);
690 nomem:
691         /* all pointers should be clean so we are done */
692         tnode_free(tn);
693 notnode:
694         return NULL;
695 }
696 
697 static struct key_vector *collapse(struct trie *t,
698                                    struct key_vector *oldtnode)
699 {
700         struct key_vector *n, *tp;
701         unsigned long i;
702 
703         /* scan the tnode looking for that one child that might still exist */
704         for (n = NULL, i = child_length(oldtnode); !n && i;)
705                 n = get_child(oldtnode, --i);
706 
707         /* compress one level */
708         tp = node_parent(oldtnode);
709         put_child_root(tp, oldtnode->key, n);
710         node_set_parent(n, tp);
711 
712         /* drop dead node */
713         node_free(oldtnode);
714 
715         return tp;
716 }
717 
718 static unsigned char update_suffix(struct key_vector *tn)
719 {
720         unsigned char slen = tn->pos;
721         unsigned long stride, i;
722         unsigned char slen_max;
723 
724         /* only vector 0 can have a suffix length greater than or equal to
725          * tn->pos + tn->bits, the second highest node will have a suffix
726          * length at most of tn->pos + tn->bits - 1
727          */
728         slen_max = min_t(unsigned char, tn->pos + tn->bits - 1, tn->slen);
729 
730         /* search though the list of children looking for nodes that might
731          * have a suffix greater than the one we currently have.  This is
732          * why we start with a stride of 2 since a stride of 1 would
733          * represent the nodes with suffix length equal to tn->pos
734          */
735         for (i = 0, stride = 0x2ul ; i < child_length(tn); i += stride) {
736                 struct key_vector *n = get_child(tn, i);
737 
738                 if (!n || (n->slen <= slen))
739                         continue;
740 
741                 /* update stride and slen based on new value */
742                 stride <<= (n->slen - slen);
743                 slen = n->slen;
744                 i &= ~(stride - 1);
745 
746                 /* stop searching if we have hit the maximum possible value */
747                 if (slen >= slen_max)
748                         break;
749         }
750 
751         tn->slen = slen;
752 
753         return slen;
754 }
755 
756 /* From "Implementing a dynamic compressed trie" by Stefan Nilsson of
757  * the Helsinki University of Technology and Matti Tikkanen of Nokia
758  * Telecommunications, page 6:
759  * "A node is doubled if the ratio of non-empty children to all
760  * children in the *doubled* node is at least 'high'."
761  *
762  * 'high' in this instance is the variable 'inflate_threshold'. It
763  * is expressed as a percentage, so we multiply it with
764  * child_length() and instead of multiplying by 2 (since the
765  * child array will be doubled by inflate()) and multiplying
766  * the left-hand side by 100 (to handle the percentage thing) we
767  * multiply the left-hand side by 50.
768  *
769  * The left-hand side may look a bit weird: child_length(tn)
770  * - tn->empty_children is of course the number of non-null children
771  * in the current node. tn->full_children is the number of "full"
772  * children, that is non-null tnodes with a skip value of 0.
773  * All of those will be doubled in the resulting inflated tnode, so
774  * we just count them one extra time here.
775  *
776  * A clearer way to write this would be:
777  *
778  * to_be_doubled = tn->full_children;
779  * not_to_be_doubled = child_length(tn) - tn->empty_children -
780  *     tn->full_children;
781  *
782  * new_child_length = child_length(tn) * 2;
783  *
784  * new_fill_factor = 100 * (not_to_be_doubled + 2*to_be_doubled) /
785  *      new_child_length;
786  * if (new_fill_factor >= inflate_threshold)
787  *
788  * ...and so on, tho it would mess up the while () loop.
789  *
790  * anyway,
791  * 100 * (not_to_be_doubled + 2*to_be_doubled) / new_child_length >=
792  *      inflate_threshold
793  *
794  * avoid a division:
795  * 100 * (not_to_be_doubled + 2*to_be_doubled) >=
796  *      inflate_threshold * new_child_length
797  *
798  * expand not_to_be_doubled and to_be_doubled, and shorten:
799  * 100 * (child_length(tn) - tn->empty_children +
800  *    tn->full_children) >= inflate_threshold * new_child_length
801  *
802  * expand new_child_length:
803  * 100 * (child_length(tn) - tn->empty_children +
804  *    tn->full_children) >=
805  *      inflate_threshold * child_length(tn) * 2
806  *
807  * shorten again:
808  * 50 * (tn->full_children + child_length(tn) -
809  *    tn->empty_children) >= inflate_threshold *
810  *    child_length(tn)
811  *
812  */
813 static inline bool should_inflate(struct key_vector *tp, struct key_vector *tn)
814 {
815         unsigned long used = child_length(tn);
816         unsigned long threshold = used;
817 
818         /* Keep root node larger */
819         threshold *= IS_TRIE(tp) ? inflate_threshold_root : inflate_threshold;
820         used -= tn_info(tn)->empty_children;
821         used += tn_info(tn)->full_children;
822 
823         /* if bits == KEYLENGTH then pos = 0, and will fail below */
824 
825         return (used > 1) && tn->pos && ((50 * used) >= threshold);
826 }
827 
828 static inline bool should_halve(struct key_vector *tp, struct key_vector *tn)
829 {
830         unsigned long used = child_length(tn);
831         unsigned long threshold = used;
832 
833         /* Keep root node larger */
834         threshold *= IS_TRIE(tp) ? halve_threshold_root : halve_threshold;
835         used -= tn_info(tn)->empty_children;
836 
837         /* if bits == KEYLENGTH then used = 100% on wrap, and will fail below */
838 
839         return (used > 1) && (tn->bits > 1) && ((100 * used) < threshold);
840 }
841 
842 static inline bool should_collapse(struct key_vector *tn)
843 {
844         unsigned long used = child_length(tn);
845 
846         used -= tn_info(tn)->empty_children;
847 
848         /* account for bits == KEYLENGTH case */
849         if ((tn->bits == KEYLENGTH) && tn_info(tn)->full_children)
850                 used -= KEY_MAX;
851 
852         /* One child or none, time to drop us from the trie */
853         return used < 2;
854 }
855 
856 #define MAX_WORK 10
857 static struct key_vector *resize(struct trie *t, struct key_vector *tn)
858 {
859 #ifdef CONFIG_IP_FIB_TRIE_STATS
860         struct trie_use_stats __percpu *stats = t->stats;
861 #endif
862         struct key_vector *tp = node_parent(tn);
863         unsigned long cindex = get_index(tn->key, tp);
864         int max_work = MAX_WORK;
865 
866         pr_debug("In tnode_resize %p inflate_threshold=%d threshold=%d\n",
867                  tn, inflate_threshold, halve_threshold);
868 
869         /* track the tnode via the pointer from the parent instead of
870          * doing it ourselves.  This way we can let RCU fully do its
871          * thing without us interfering
872          */
873         BUG_ON(tn != get_child(tp, cindex));
874 
875         /* Double as long as the resulting node has a number of
876          * nonempty nodes that are above the threshold.
877          */
878         while (should_inflate(tp, tn) && max_work) {
879                 tp = inflate(t, tn);
880                 if (!tp) {
881 #ifdef CONFIG_IP_FIB_TRIE_STATS
882                         this_cpu_inc(stats->resize_node_skipped);
883 #endif
884                         break;
885                 }
886 
887                 max_work--;
888                 tn = get_child(tp, cindex);
889         }
890 
891         /* update parent in case inflate failed */
892         tp = node_parent(tn);
893 
894         /* Return if at least one inflate is run */
895         if (max_work != MAX_WORK)
896                 return tp;
897 
898         /* Halve as long as the number of empty children in this
899          * node is above threshold.
900          */
901         while (should_halve(tp, tn) && max_work) {
902                 tp = halve(t, tn);
903                 if (!tp) {
904 #ifdef CONFIG_IP_FIB_TRIE_STATS
905                         this_cpu_inc(stats->resize_node_skipped);
906 #endif
907                         break;
908                 }
909 
910                 max_work--;
911                 tn = get_child(tp, cindex);
912         }
913 
914         /* Only one child remains */
915         if (should_collapse(tn))
916                 return collapse(t, tn);
917 
918         /* update parent in case halve failed */
919         return node_parent(tn);
920 }
921 
922 static void node_pull_suffix(struct key_vector *tn, unsigned char slen)
923 {
924         unsigned char node_slen = tn->slen;
925 
926         while ((node_slen > tn->pos) && (node_slen > slen)) {
927                 slen = update_suffix(tn);
928                 if (node_slen == slen)
929                         break;
930 
931                 tn = node_parent(tn);
932                 node_slen = tn->slen;
933         }
934 }
935 
936 static void node_push_suffix(struct key_vector *tn, unsigned char slen)
937 {
938         while (tn->slen < slen) {
939                 tn->slen = slen;
940                 tn = node_parent(tn);
941         }
942 }
943 
944 /* rcu_read_lock needs to be hold by caller from readside */
945 static struct key_vector *fib_find_node(struct trie *t,
946                                         struct key_vector **tp, u32 key)
947 {
948         struct key_vector *pn, *n = t->kv;
949         unsigned long index = 0;
950 
951         do {
952                 pn = n;
953                 n = get_child_rcu(n, index);
954 
955                 if (!n)
956                         break;
957 
958                 index = get_cindex(key, n);
959 
960                 /* This bit of code is a bit tricky but it combines multiple
961                  * checks into a single check.  The prefix consists of the
962                  * prefix plus zeros for the bits in the cindex. The index
963                  * is the difference between the key and this value.  From
964                  * this we can actually derive several pieces of data.
965                  *   if (index >= (1ul << bits))
966                  *     we have a mismatch in skip bits and failed
967                  *   else
968                  *     we know the value is cindex
969                  *
970                  * This check is safe even if bits == KEYLENGTH due to the
971                  * fact that we can only allocate a node with 32 bits if a
972                  * long is greater than 32 bits.
973                  */
974                 if (index >= (1ul << n->bits)) {
975                         n = NULL;
976                         break;
977                 }
978 
979                 /* keep searching until we find a perfect match leaf or NULL */
980         } while (IS_TNODE(n));
981 
982         *tp = pn;
983 
984         return n;
985 }
986 
987 /* Return the first fib alias matching TOS with
988  * priority less than or equal to PRIO.
989  */
990 static struct fib_alias *fib_find_alias(struct hlist_head *fah, u8 slen,
991                                         u8 tos, u32 prio, u32 tb_id)
992 {
993         struct fib_alias *fa;
994 
995         if (!fah)
996                 return NULL;
997 
998         hlist_for_each_entry(fa, fah, fa_list) {
999                 if (fa->fa_slen < slen)
1000                         continue;
1001                 if (fa->fa_slen != slen)
1002                         break;
1003                 if (fa->tb_id > tb_id)
1004                         continue;
1005                 if (fa->tb_id != tb_id)
1006                         break;
1007                 if (fa->fa_tos > tos)
1008                         continue;
1009                 if (fa->fa_info->fib_priority >= prio || fa->fa_tos < tos)
1010                         return fa;
1011         }
1012 
1013         return NULL;
1014 }
1015 
1016 static void trie_rebalance(struct trie *t, struct key_vector *tn)
1017 {
1018         while (!IS_TRIE(tn))
1019                 tn = resize(t, tn);
1020 }
1021 
1022 static int fib_insert_node(struct trie *t, struct key_vector *tp,
1023                            struct fib_alias *new, t_key key)
1024 {
1025         struct key_vector *n, *l;
1026 
1027         l = leaf_new(key, new);
1028         if (!l)
1029                 goto noleaf;
1030 
1031         /* retrieve child from parent node */
1032         n = get_child(tp, get_index(key, tp));
1033 
1034         /* Case 2: n is a LEAF or a TNODE and the key doesn't match.
1035          *
1036          *  Add a new tnode here
1037          *  first tnode need some special handling
1038          *  leaves us in position for handling as case 3
1039          */
1040         if (n) {
1041                 struct key_vector *tn;
1042 
1043                 tn = tnode_new(key, __fls(key ^ n->key), 1);
1044                 if (!tn)
1045                         goto notnode;
1046 
1047                 /* initialize routes out of node */
1048                 NODE_INIT_PARENT(tn, tp);
1049                 put_child(tn, get_index(key, tn) ^ 1, n);
1050 
1051                 /* start adding routes into the node */
1052                 put_child_root(tp, key, tn);
1053                 node_set_parent(n, tn);
1054 
1055                 /* parent now has a NULL spot where the leaf can go */
1056                 tp = tn;
1057         }
1058 
1059         /* Case 3: n is NULL, and will just insert a new leaf */
1060         node_push_suffix(tp, new->fa_slen);
1061         NODE_INIT_PARENT(l, tp);
1062         put_child_root(tp, key, l);
1063         trie_rebalance(t, tp);
1064 
1065         return 0;
1066 notnode:
1067         node_free(l);
1068 noleaf:
1069         return -ENOMEM;
1070 }
1071 
1072 static int fib_insert_alias(struct trie *t, struct key_vector *tp,
1073                             struct key_vector *l, struct fib_alias *new,
1074                             struct fib_alias *fa, t_key key)
1075 {
1076         if (!l)
1077                 return fib_insert_node(t, tp, new, key);
1078 
1079         if (fa) {
1080                 hlist_add_before_rcu(&new->fa_list, &fa->fa_list);
1081         } else {
1082                 struct fib_alias *last;
1083 
1084                 hlist_for_each_entry(last, &l->leaf, fa_list) {
1085                         if (new->fa_slen < last->fa_slen)
1086                                 break;
1087                         if ((new->fa_slen == last->fa_slen) &&
1088                             (new->tb_id > last->tb_id))
1089                                 break;
1090                         fa = last;
1091                 }
1092 
1093                 if (fa)
1094                         hlist_add_behind_rcu(&new->fa_list, &fa->fa_list);
1095                 else
1096                         hlist_add_head_rcu(&new->fa_list, &l->leaf);
1097         }
1098 
1099         /* if we added to the tail node then we need to update slen */
1100         if (l->slen < new->fa_slen) {
1101                 l->slen = new->fa_slen;
1102                 node_push_suffix(tp, new->fa_slen);
1103         }
1104 
1105         return 0;
1106 }
1107 
1108 /* Caller must hold RTNL. */
1109 int fib_table_insert(struct net *net, struct fib_table *tb,
1110                      struct fib_config *cfg)
1111 {
1112         struct trie *t = (struct trie *)tb->tb_data;
1113         struct fib_alias *fa, *new_fa;
1114         struct key_vector *l, *tp;
1115         u16 nlflags = NLM_F_EXCL;
1116         struct fib_info *fi;
1117         u8 plen = cfg->fc_dst_len;
1118         u8 slen = KEYLENGTH - plen;
1119         u8 tos = cfg->fc_tos;
1120         u32 key;
1121         int err;
1122 
1123         if (plen > KEYLENGTH)
1124                 return -EINVAL;
1125 
1126         key = ntohl(cfg->fc_dst);
1127 
1128         pr_debug("Insert table=%u %08x/%d\n", tb->tb_id, key, plen);
1129 
1130         if ((plen < KEYLENGTH) && (key << plen))
1131                 return -EINVAL;
1132 
1133         fi = fib_create_info(cfg);
1134         if (IS_ERR(fi)) {
1135                 err = PTR_ERR(fi);
1136                 goto err;
1137         }
1138 
1139         l = fib_find_node(t, &tp, key);
1140         fa = l ? fib_find_alias(&l->leaf, slen, tos, fi->fib_priority,
1141                                 tb->tb_id) : NULL;
1142 
1143         /* Now fa, if non-NULL, points to the first fib alias
1144          * with the same keys [prefix,tos,priority], if such key already
1145          * exists or to the node before which we will insert new one.
1146          *
1147          * If fa is NULL, we will need to allocate a new one and
1148          * insert to the tail of the section matching the suffix length
1149          * of the new alias.
1150          */
1151 
1152         if (fa && fa->fa_tos == tos &&
1153             fa->fa_info->fib_priority == fi->fib_priority) {
1154                 struct fib_alias *fa_first, *fa_match;
1155 
1156                 err = -EEXIST;
1157                 if (cfg->fc_nlflags & NLM_F_EXCL)
1158                         goto out;
1159 
1160                 nlflags &= ~NLM_F_EXCL;
1161 
1162                 /* We have 2 goals:
1163                  * 1. Find exact match for type, scope, fib_info to avoid
1164                  * duplicate routes
1165                  * 2. Find next 'fa' (or head), NLM_F_APPEND inserts before it
1166                  */
1167                 fa_match = NULL;
1168                 fa_first = fa;
1169                 hlist_for_each_entry_from(fa, fa_list) {
1170                         if ((fa->fa_slen != slen) ||
1171                             (fa->tb_id != tb->tb_id) ||
1172                             (fa->fa_tos != tos))
1173                                 break;
1174                         if (fa->fa_info->fib_priority != fi->fib_priority)
1175                                 break;
1176                         if (fa->fa_type == cfg->fc_type &&
1177                             fa->fa_info == fi) {
1178                                 fa_match = fa;
1179                                 break;
1180                         }
1181                 }
1182 
1183                 if (cfg->fc_nlflags & NLM_F_REPLACE) {
1184                         struct fib_info *fi_drop;
1185                         u8 state;
1186 
1187                         nlflags |= NLM_F_REPLACE;
1188                         fa = fa_first;
1189                         if (fa_match) {
1190                                 if (fa == fa_match)
1191                                         err = 0;
1192                                 goto out;
1193                         }
1194                         err = -ENOBUFS;
1195                         new_fa = kmem_cache_alloc(fn_alias_kmem, GFP_KERNEL);
1196                         if (!new_fa)
1197                                 goto out;
1198 
1199                         fi_drop = fa->fa_info;
1200                         new_fa->fa_tos = fa->fa_tos;
1201                         new_fa->fa_info = fi;
1202                         new_fa->fa_type = cfg->fc_type;
1203                         state = fa->fa_state;
1204                         new_fa->fa_state = state & ~FA_S_ACCESSED;
1205                         new_fa->fa_slen = fa->fa_slen;
1206                         new_fa->tb_id = tb->tb_id;
1207                         new_fa->fa_default = -1;
1208 
1209                         hlist_replace_rcu(&fa->fa_list, &new_fa->fa_list);
1210 
1211                         alias_free_mem_rcu(fa);
1212 
1213                         fib_release_info(fi_drop);
1214                         if (state & FA_S_ACCESSED)
1215                                 rt_cache_flush(cfg->fc_nlinfo.nl_net);
1216 
1217                         call_fib_entry_notifiers(net, FIB_EVENT_ENTRY_ADD,
1218                                                  key, plen, fi,
1219                                                  new_fa->fa_tos, cfg->fc_type,
1220                                                  tb->tb_id, cfg->fc_nlflags);
1221                         rtmsg_fib(RTM_NEWROUTE, htonl(key), new_fa, plen,
1222                                 tb->tb_id, &cfg->fc_nlinfo, nlflags);
1223 
1224                         goto succeeded;
1225                 }
1226                 /* Error if we find a perfect match which
1227                  * uses the same scope, type, and nexthop
1228                  * information.
1229                  */
1230                 if (fa_match)
1231                         goto out;
1232 
1233                 if (cfg->fc_nlflags & NLM_F_APPEND)
1234                         nlflags |= NLM_F_APPEND;
1235                 else
1236                         fa = fa_first;
1237         }
1238         err = -ENOENT;
1239         if (!(cfg->fc_nlflags & NLM_F_CREATE))
1240                 goto out;
1241 
1242         nlflags |= NLM_F_CREATE;
1243         err = -ENOBUFS;
1244         new_fa = kmem_cache_alloc(fn_alias_kmem, GFP_KERNEL);
1245         if (!new_fa)
1246                 goto out;
1247 
1248         new_fa->fa_info = fi;
1249         new_fa->fa_tos = tos;
1250         new_fa->fa_type = cfg->fc_type;
1251         new_fa->fa_state = 0;
1252         new_fa->fa_slen = slen;
1253         new_fa->tb_id = tb->tb_id;
1254         new_fa->fa_default = -1;
1255 
1256         /* Insert new entry to the list. */
1257         err = fib_insert_alias(t, tp, l, new_fa, fa, key);
1258         if (err)
1259                 goto out_free_new_fa;
1260 
1261         if (!plen)
1262                 tb->tb_num_default++;
1263 
1264         rt_cache_flush(cfg->fc_nlinfo.nl_net);
1265         call_fib_entry_notifiers(net, FIB_EVENT_ENTRY_ADD, key, plen, fi, tos,
1266                                  cfg->fc_type, tb->tb_id, cfg->fc_nlflags);
1267         rtmsg_fib(RTM_NEWROUTE, htonl(key), new_fa, plen, new_fa->tb_id,
1268                   &cfg->fc_nlinfo, nlflags);
1269 succeeded:
1270         return 0;
1271 
1272 out_free_new_fa:
1273         kmem_cache_free(fn_alias_kmem, new_fa);
1274 out:
1275         fib_release_info(fi);
1276 err:
1277         return err;
1278 }
1279 
1280 static inline t_key prefix_mismatch(t_key key, struct key_vector *n)
1281 {
1282         t_key prefix = n->key;
1283 
1284         return (key ^ prefix) & (prefix | -prefix);
1285 }
1286 
1287 /* should be called with rcu_read_lock */
1288 int fib_table_lookup(struct fib_table *tb, const struct flowi4 *flp,
1289                      struct fib_result *res, int fib_flags)
1290 {
1291         struct trie *t = (struct trie *) tb->tb_data;
1292 #ifdef CONFIG_IP_FIB_TRIE_STATS
1293         struct trie_use_stats __percpu *stats = t->stats;
1294 #endif
1295         const t_key key = ntohl(flp->daddr);
1296         struct key_vector *n, *pn;
1297         struct fib_alias *fa;
1298         unsigned long index;
1299         t_key cindex;
1300 
1301         trace_fib_table_lookup(tb->tb_id, flp);
1302 
1303         pn = t->kv;
1304         cindex = 0;
1305 
1306         n = get_child_rcu(pn, cindex);
1307         if (!n)
1308                 return -EAGAIN;
1309 
1310 #ifdef CONFIG_IP_FIB_TRIE_STATS
1311         this_cpu_inc(stats->gets);
1312 #endif
1313 
1314         /* Step 1: Travel to the longest prefix match in the trie */
1315         for (;;) {
1316                 index = get_cindex(key, n);
1317 
1318                 /* This bit of code is a bit tricky but it combines multiple
1319                  * checks into a single check.  The prefix consists of the
1320                  * prefix plus zeros for the "bits" in the prefix. The index
1321                  * is the difference between the key and this value.  From
1322                  * this we can actually derive several pieces of data.
1323                  *   if (index >= (1ul << bits))
1324                  *     we have a mismatch in skip bits and failed
1325                  *   else
1326                  *     we know the value is cindex
1327                  *
1328                  * This check is safe even if bits == KEYLENGTH due to the
1329                  * fact that we can only allocate a node with 32 bits if a
1330                  * long is greater than 32 bits.
1331                  */
1332                 if (index >= (1ul << n->bits))
1333                         break;
1334 
1335                 /* we have found a leaf. Prefixes have already been compared */
1336                 if (IS_LEAF(n))
1337                         goto found;
1338 
1339                 /* only record pn and cindex if we are going to be chopping
1340                  * bits later.  Otherwise we are just wasting cycles.
1341                  */
1342                 if (n->slen > n->pos) {
1343                         pn = n;
1344                         cindex = index;
1345                 }
1346 
1347                 n = get_child_rcu(n, index);
1348                 if (unlikely(!n))
1349                         goto backtrace;
1350         }
1351 
1352         /* Step 2: Sort out leaves and begin backtracing for longest prefix */
1353         for (;;) {
1354                 /* record the pointer where our next node pointer is stored */
1355                 struct key_vector __rcu **cptr = n->tnode;
1356 
1357                 /* This test verifies that none of the bits that differ
1358                  * between the key and the prefix exist in the region of
1359                  * the lsb and higher in the prefix.
1360                  */
1361                 if (unlikely(prefix_mismatch(key, n)) || (n->slen == n->pos))
1362                         goto backtrace;
1363 
1364                 /* exit out and process leaf */
1365                 if (unlikely(IS_LEAF(n)))
1366                         break;
1367 
1368                 /* Don't bother recording parent info.  Since we are in
1369                  * prefix match mode we will have to come back to wherever
1370                  * we started this traversal anyway
1371                  */
1372 
1373                 while ((n = rcu_dereference(*cptr)) == NULL) {
1374 backtrace:
1375 #ifdef CONFIG_IP_FIB_TRIE_STATS
1376                         if (!n)
1377                                 this_cpu_inc(stats->null_node_hit);
1378 #endif
1379                         /* If we are at cindex 0 there are no more bits for
1380                          * us to strip at this level so we must ascend back
1381                          * up one level to see if there are any more bits to
1382                          * be stripped there.
1383                          */
1384                         while (!cindex) {
1385                                 t_key pkey = pn->key;
1386 
1387                                 /* If we don't have a parent then there is
1388                                  * nothing for us to do as we do not have any
1389                                  * further nodes to parse.
1390                                  */
1391                                 if (IS_TRIE(pn))
1392                                         return -EAGAIN;
1393 #ifdef CONFIG_IP_FIB_TRIE_STATS
1394                                 this_cpu_inc(stats->backtrack);
1395 #endif
1396                                 /* Get Child's index */
1397                                 pn = node_parent_rcu(pn);
1398                                 cindex = get_index(pkey, pn);
1399                         }
1400 
1401                         /* strip the least significant bit from the cindex */
1402                         cindex &= cindex - 1;
1403 
1404                         /* grab pointer for next child node */
1405                         cptr = &pn->tnode[cindex];
1406                 }
1407         }
1408 
1409 found:
1410         /* this line carries forward the xor from earlier in the function */
1411         index = key ^ n->key;
1412 
1413         /* Step 3: Process the leaf, if that fails fall back to backtracing */
1414         hlist_for_each_entry_rcu(fa, &n->leaf, fa_list) {
1415                 struct fib_info *fi = fa->fa_info;
1416                 int nhsel, err;
1417 
1418                 if ((BITS_PER_LONG > KEYLENGTH) || (fa->fa_slen < KEYLENGTH)) {
1419                         if (index >= (1ul << fa->fa_slen))
1420                                 continue;
1421                 }
1422                 if (fa->fa_tos && fa->fa_tos != flp->flowi4_tos)
1423                         continue;
1424                 if (fi->fib_dead)
1425                         continue;
1426                 if (fa->fa_info->fib_scope < flp->flowi4_scope)
1427                         continue;
1428                 fib_alias_accessed(fa);
1429                 err = fib_props[fa->fa_type].error;
1430                 if (unlikely(err < 0)) {
1431 #ifdef CONFIG_IP_FIB_TRIE_STATS
1432                         this_cpu_inc(stats->semantic_match_passed);
1433 #endif
1434                         return err;
1435                 }
1436                 if (fi->fib_flags & RTNH_F_DEAD)
1437                         continue;
1438                 for (nhsel = 0; nhsel < fi->fib_nhs; nhsel++) {
1439                         const struct fib_nh *nh = &fi->fib_nh[nhsel];
1440                         struct in_device *in_dev = __in_dev_get_rcu(nh->nh_dev);
1441 
1442                         if (nh->nh_flags & RTNH_F_DEAD)
1443                                 continue;
1444                         if (in_dev &&
1445                             IN_DEV_IGNORE_ROUTES_WITH_LINKDOWN(in_dev) &&
1446                             nh->nh_flags & RTNH_F_LINKDOWN &&
1447                             !(fib_flags & FIB_LOOKUP_IGNORE_LINKSTATE))
1448                                 continue;
1449                         if (!(flp->flowi4_flags & FLOWI_FLAG_SKIP_NH_OIF)) {
1450                                 if (flp->flowi4_oif &&
1451                                     flp->flowi4_oif != nh->nh_oif)
1452                                         continue;
1453                         }
1454 
1455                         if (!(fib_flags & FIB_LOOKUP_NOREF))
1456                                 atomic_inc(&fi->fib_clntref);
1457 
1458                         res->prefixlen = KEYLENGTH - fa->fa_slen;
1459                         res->nh_sel = nhsel;
1460                         res->type = fa->fa_type;
1461                         res->scope = fi->fib_scope;
1462                         res->fi = fi;
1463                         res->table = tb;
1464                         res->fa_head = &n->leaf;
1465 #ifdef CONFIG_IP_FIB_TRIE_STATS
1466                         this_cpu_inc(stats->semantic_match_passed);
1467 #endif
1468                         trace_fib_table_lookup_nh(nh);
1469 
1470                         return err;
1471                 }
1472         }
1473 #ifdef CONFIG_IP_FIB_TRIE_STATS
1474         this_cpu_inc(stats->semantic_match_miss);
1475 #endif
1476         goto backtrace;
1477 }
1478 EXPORT_SYMBOL_GPL(fib_table_lookup);
1479 
1480 static void fib_remove_alias(struct trie *t, struct key_vector *tp,
1481                              struct key_vector *l, struct fib_alias *old)
1482 {
1483         /* record the location of the previous list_info entry */
1484         struct hlist_node **pprev = old->fa_list.pprev;
1485         struct fib_alias *fa = hlist_entry(pprev, typeof(*fa), fa_list.next);
1486 
1487         /* remove the fib_alias from the list */
1488         hlist_del_rcu(&old->fa_list);
1489 
1490         /* if we emptied the list this leaf will be freed and we can sort
1491          * out parent suffix lengths as a part of trie_rebalance
1492          */
1493         if (hlist_empty(&l->leaf)) {
1494                 if (tp->slen == l->slen)
1495                         node_pull_suffix(tp, tp->pos);
1496                 put_child_root(tp, l->key, NULL);
1497                 node_free(l);
1498                 trie_rebalance(t, tp);
1499                 return;
1500         }
1501 
1502         /* only access fa if it is pointing at the last valid hlist_node */
1503         if (*pprev)
1504                 return;
1505 
1506         /* update the trie with the latest suffix length */
1507         l->slen = fa->fa_slen;
1508         node_pull_suffix(tp, fa->fa_slen);
1509 }
1510 
1511 /* Caller must hold RTNL. */
1512 int fib_table_delete(struct net *net, struct fib_table *tb,
1513                      struct fib_config *cfg)
1514 {
1515         struct trie *t = (struct trie *) tb->tb_data;
1516         struct fib_alias *fa, *fa_to_delete;
1517         struct key_vector *l, *tp;
1518         u8 plen = cfg->fc_dst_len;
1519         u8 slen = KEYLENGTH - plen;
1520         u8 tos = cfg->fc_tos;
1521         u32 key;
1522 
1523         if (plen > KEYLENGTH)
1524                 return -EINVAL;
1525 
1526         key = ntohl(cfg->fc_dst);
1527 
1528         if ((plen < KEYLENGTH) && (key << plen))
1529                 return -EINVAL;
1530 
1531         l = fib_find_node(t, &tp, key);
1532         if (!l)
1533                 return -ESRCH;
1534 
1535         fa = fib_find_alias(&l->leaf, slen, tos, 0, tb->tb_id);
1536         if (!fa)
1537                 return -ESRCH;
1538 
1539         pr_debug("Deleting %08x/%d tos=%d t=%p\n", key, plen, tos, t);
1540 
1541         fa_to_delete = NULL;
1542         hlist_for_each_entry_from(fa, fa_list) {
1543                 struct fib_info *fi = fa->fa_info;
1544 
1545                 if ((fa->fa_slen != slen) ||
1546                     (fa->tb_id != tb->tb_id) ||
1547                     (fa->fa_tos != tos))
1548                         break;
1549 
1550                 if ((!cfg->fc_type || fa->fa_type == cfg->fc_type) &&
1551                     (cfg->fc_scope == RT_SCOPE_NOWHERE ||
1552                      fa->fa_info->fib_scope == cfg->fc_scope) &&
1553                     (!cfg->fc_prefsrc ||
1554                      fi->fib_prefsrc == cfg->fc_prefsrc) &&
1555                     (!cfg->fc_protocol ||
1556                      fi->fib_protocol == cfg->fc_protocol) &&
1557                     fib_nh_match(cfg, fi) == 0) {
1558                         fa_to_delete = fa;
1559                         break;
1560                 }
1561         }
1562 
1563         if (!fa_to_delete)
1564                 return -ESRCH;
1565 
1566         call_fib_entry_notifiers(net, FIB_EVENT_ENTRY_DEL, key, plen,
1567                                  fa_to_delete->fa_info, tos, cfg->fc_type,
1568                                  tb->tb_id, 0);
1569         rtmsg_fib(RTM_DELROUTE, htonl(key), fa_to_delete, plen, tb->tb_id,
1570                   &cfg->fc_nlinfo, 0);
1571 
1572         if (!plen)
1573                 tb->tb_num_default--;
1574 
1575         fib_remove_alias(t, tp, l, fa_to_delete);
1576 
1577         if (fa_to_delete->fa_state & FA_S_ACCESSED)
1578                 rt_cache_flush(cfg->fc_nlinfo.nl_net);
1579 
1580         fib_release_info(fa_to_delete->fa_info);
1581         alias_free_mem_rcu(fa_to_delete);
1582         return 0;
1583 }
1584 
1585 /* Scan for the next leaf starting at the provided key value */
1586 static struct key_vector *leaf_walk_rcu(struct key_vector **tn, t_key key)
1587 {
1588         struct key_vector *pn, *n = *tn;
1589         unsigned long cindex;
1590 
1591         /* this loop is meant to try and find the key in the trie */
1592         do {
1593                 /* record parent and next child index */
1594                 pn = n;
1595                 cindex = (key > pn->key) ? get_index(key, pn) : 0;
1596 
1597                 if (cindex >> pn->bits)
1598                         break;
1599 
1600                 /* descend into the next child */
1601                 n = get_child_rcu(pn, cindex++);
1602                 if (!n)
1603                         break;
1604 
1605                 /* guarantee forward progress on the keys */
1606                 if (IS_LEAF(n) && (n->key >= key))
1607                         goto found;
1608         } while (IS_TNODE(n));
1609 
1610         /* this loop will search for the next leaf with a greater key */
1611         while (!IS_TRIE(pn)) {
1612                 /* if we exhausted the parent node we will need to climb */
1613                 if (cindex >= (1ul << pn->bits)) {
1614                         t_key pkey = pn->key;
1615 
1616                         pn = node_parent_rcu(pn);
1617                         cindex = get_index(pkey, pn) + 1;
1618                         continue;
1619                 }
1620 
1621                 /* grab the next available node */
1622                 n = get_child_rcu(pn, cindex++);
1623                 if (!n)
1624                         continue;
1625 
1626                 /* no need to compare keys since we bumped the index */
1627                 if (IS_LEAF(n))
1628                         goto found;
1629 
1630                 /* Rescan start scanning in new node */
1631                 pn = n;
1632                 cindex = 0;
1633         }
1634 
1635         *tn = pn;
1636         return NULL; /* Root of trie */
1637 found:
1638         /* if we are at the limit for keys just return NULL for the tnode */
1639         *tn = pn;
1640         return n;
1641 }
1642 
1643 static void fib_trie_free(struct fib_table *tb)
1644 {
1645         struct trie *t = (struct trie *)tb->tb_data;
1646         struct key_vector *pn = t->kv;
1647         unsigned long cindex = 1;
1648         struct hlist_node *tmp;
1649         struct fib_alias *fa;
1650 
1651         /* walk trie in reverse order and free everything */
1652         for (;;) {
1653                 struct key_vector *n;
1654 
1655                 if (!(cindex--)) {
1656                         t_key pkey = pn->key;
1657 
1658                         if (IS_TRIE(pn))
1659                                 break;
1660 
1661                         n = pn;
1662                         pn = node_parent(pn);
1663 
1664                         /* drop emptied tnode */
1665                         put_child_root(pn, n->key, NULL);
1666                         node_free(n);
1667 
1668                         cindex = get_index(pkey, pn);
1669 
1670                         continue;
1671                 }
1672 
1673                 /* grab the next available node */
1674                 n = get_child(pn, cindex);
1675                 if (!n)
1676                         continue;
1677 
1678                 if (IS_TNODE(n)) {
1679                         /* record pn and cindex for leaf walking */
1680                         pn = n;
1681                         cindex = 1ul << n->bits;
1682 
1683                         continue;
1684                 }
1685 
1686                 hlist_for_each_entry_safe(fa, tmp, &n->leaf, fa_list) {
1687                         hlist_del_rcu(&fa->fa_list);
1688                         alias_free_mem_rcu(fa);
1689                 }
1690 
1691                 put_child_root(pn, n->key, NULL);
1692                 node_free(n);
1693         }
1694 
1695 #ifdef CONFIG_IP_FIB_TRIE_STATS
1696         free_percpu(t->stats);
1697 #endif
1698         kfree(tb);
1699 }
1700 
1701 struct fib_table *fib_trie_unmerge(struct fib_table *oldtb)
1702 {
1703         struct trie *ot = (struct trie *)oldtb->tb_data;
1704         struct key_vector *l, *tp = ot->kv;
1705         struct fib_table *local_tb;
1706         struct fib_alias *fa;
1707         struct trie *lt;
1708         t_key key = 0;
1709 
1710         if (oldtb->tb_data == oldtb->__data)
1711                 return oldtb;
1712 
1713         local_tb = fib_trie_table(RT_TABLE_LOCAL, NULL);
1714         if (!local_tb)
1715                 return NULL;
1716 
1717         lt = (struct trie *)local_tb->tb_data;
1718 
1719         while ((l = leaf_walk_rcu(&tp, key)) != NULL) {
1720                 struct key_vector *local_l = NULL, *local_tp;
1721 
1722                 hlist_for_each_entry_rcu(fa, &l->leaf, fa_list) {
1723                         struct fib_alias *new_fa;
1724 
1725                         if (local_tb->tb_id != fa->tb_id)
1726                                 continue;
1727 
1728                         /* clone fa for new local table */
1729                         new_fa = kmem_cache_alloc(fn_alias_kmem, GFP_KERNEL);
1730                         if (!new_fa)
1731                                 goto out;
1732 
1733                         memcpy(new_fa, fa, sizeof(*fa));
1734 
1735                         /* insert clone into table */
1736                         if (!local_l)
1737                                 local_l = fib_find_node(lt, &local_tp, l->key);
1738 
1739                         if (fib_insert_alias(lt, local_tp, local_l, new_fa,
1740                                              NULL, l->key)) {
1741                                 kmem_cache_free(fn_alias_kmem, new_fa);
1742                                 goto out;
1743                         }
1744                 }
1745 
1746                 /* stop loop if key wrapped back to 0 */
1747                 key = l->key + 1;
1748                 if (key < l->key)
1749                         break;
1750         }
1751 
1752         return local_tb;
1753 out:
1754         fib_trie_free(local_tb);
1755 
1756         return NULL;
1757 }
1758 
1759 /* Caller must hold RTNL */
1760 void fib_table_flush_external(struct fib_table *tb)
1761 {
1762         struct trie *t = (struct trie *)tb->tb_data;
1763         struct key_vector *pn = t->kv;
1764         unsigned long cindex = 1;
1765         struct hlist_node *tmp;
1766         struct fib_alias *fa;
1767 
1768         /* walk trie in reverse order */
1769         for (;;) {
1770                 unsigned char slen = 0;
1771                 struct key_vector *n;
1772 
1773                 if (!(cindex--)) {
1774                         t_key pkey = pn->key;
1775 
1776                         /* cannot resize the trie vector */
1777                         if (IS_TRIE(pn))
1778                                 break;
1779 
1780                         /* update the suffix to address pulled leaves */
1781                         if (pn->slen > pn->pos)
1782                                 update_suffix(pn);
1783 
1784                         /* resize completed node */
1785                         pn = resize(t, pn);
1786                         cindex = get_index(pkey, pn);
1787 
1788                         continue;
1789                 }
1790 
1791                 /* grab the next available node */
1792                 n = get_child(pn, cindex);
1793                 if (!n)
1794                         continue;
1795 
1796                 if (IS_TNODE(n)) {
1797                         /* record pn and cindex for leaf walking */
1798                         pn = n;
1799                         cindex = 1ul << n->bits;
1800 
1801                         continue;
1802                 }
1803 
1804                 hlist_for_each_entry_safe(fa, tmp, &n->leaf, fa_list) {
1805                         /* if alias was cloned to local then we just
1806                          * need to remove the local copy from main
1807                          */
1808                         if (tb->tb_id != fa->tb_id) {
1809                                 hlist_del_rcu(&fa->fa_list);
1810                                 alias_free_mem_rcu(fa);
1811                                 continue;
1812                         }
1813 
1814                         /* record local slen */
1815                         slen = fa->fa_slen;
1816                 }
1817 
1818                 /* update leaf slen */
1819                 n->slen = slen;
1820 
1821                 if (hlist_empty(&n->leaf)) {
1822                         put_child_root(pn, n->key, NULL);
1823                         node_free(n);
1824                 }
1825         }
1826 }
1827 
1828 /* Caller must hold RTNL. */
1829 int fib_table_flush(struct net *net, struct fib_table *tb)
1830 {
1831         struct trie *t = (struct trie *)tb->tb_data;
1832         struct key_vector *pn = t->kv;
1833         unsigned long cindex = 1;
1834         struct hlist_node *tmp;
1835         struct fib_alias *fa;
1836         int found = 0;
1837 
1838         /* walk trie in reverse order */
1839         for (;;) {
1840                 unsigned char slen = 0;
1841                 struct key_vector *n;
1842 
1843                 if (!(cindex--)) {
1844                         t_key pkey = pn->key;
1845 
1846                         /* cannot resize the trie vector */
1847                         if (IS_TRIE(pn))
1848                                 break;
1849 
1850                         /* update the suffix to address pulled leaves */
1851                         if (pn->slen > pn->pos)
1852                                 update_suffix(pn);
1853 
1854                         /* resize completed node */
1855                         pn = resize(t, pn);
1856                         cindex = get_index(pkey, pn);
1857 
1858                         continue;
1859                 }
1860 
1861                 /* grab the next available node */
1862                 n = get_child(pn, cindex);
1863                 if (!n)
1864                         continue;
1865 
1866                 if (IS_TNODE(n)) {
1867                         /* record pn and cindex for leaf walking */
1868                         pn = n;
1869                         cindex = 1ul << n->bits;
1870 
1871                         continue;
1872                 }
1873 
1874                 hlist_for_each_entry_safe(fa, tmp, &n->leaf, fa_list) {
1875                         struct fib_info *fi = fa->fa_info;
1876 
1877                         if (!fi || !(fi->fib_flags & RTNH_F_DEAD)) {
1878                                 slen = fa->fa_slen;
1879                                 continue;
1880                         }
1881 
1882                         call_fib_entry_notifiers(net, FIB_EVENT_ENTRY_DEL,
1883                                                  n->key,
1884                                                  KEYLENGTH - fa->fa_slen,
1885                                                  fi, fa->fa_tos, fa->fa_type,
1886                                                  tb->tb_id, 0);
1887                         hlist_del_rcu(&fa->fa_list);
1888                         fib_release_info(fa->fa_info);
1889                         alias_free_mem_rcu(fa);
1890                         found++;
1891                 }
1892 
1893                 /* update leaf slen */
1894                 n->slen = slen;
1895 
1896                 if (hlist_empty(&n->leaf)) {
1897                         put_child_root(pn, n->key, NULL);
1898                         node_free(n);
1899                 }
1900         }
1901 
1902         pr_debug("trie_flush found=%d\n", found);
1903         return found;
1904 }
1905 
1906 static void __trie_free_rcu(struct rcu_head *head)
1907 {
1908         struct fib_table *tb = container_of(head, struct fib_table, rcu);
1909 #ifdef CONFIG_IP_FIB_TRIE_STATS
1910         struct trie *t = (struct trie *)tb->tb_data;
1911 
1912         if (tb->tb_data == tb->__data)
1913                 free_percpu(t->stats);
1914 #endif /* CONFIG_IP_FIB_TRIE_STATS */
1915         kfree(tb);
1916 }
1917 
1918 void fib_free_table(struct fib_table *tb)
1919 {
1920         call_rcu(&tb->rcu, __trie_free_rcu);
1921 }
1922 
1923 static int fn_trie_dump_leaf(struct key_vector *l, struct fib_table *tb,
1924                              struct sk_buff *skb, struct netlink_callback *cb)
1925 {
1926         __be32 xkey = htonl(l->key);
1927         struct fib_alias *fa;
1928         int i, s_i;
1929 
1930         s_i = cb->args[4];
1931         i = 0;
1932 
1933         /* rcu_read_lock is hold by caller */
1934         hlist_for_each_entry_rcu(fa, &l->leaf, fa_list) {
1935                 if (i < s_i) {
1936                         i++;
1937                         continue;
1938                 }
1939 
1940                 if (tb->tb_id != fa->tb_id) {
1941                         i++;
1942                         continue;
1943                 }
1944 
1945                 if (fib_dump_info(skb, NETLINK_CB(cb->skb).portid,
1946                                   cb->nlh->nlmsg_seq,
1947                                   RTM_NEWROUTE,
1948                                   tb->tb_id,
1949                                   fa->fa_type,
1950                                   xkey,
1951                                   KEYLENGTH - fa->fa_slen,
1952                                   fa->fa_tos,
1953                                   fa->fa_info, NLM_F_MULTI) < 0) {
1954                         cb->args[4] = i;
1955                         return -1;
1956                 }
1957                 i++;
1958         }
1959 
1960         cb->args[4] = i;
1961         return skb->len;
1962 }
1963 
1964 /* rcu_read_lock needs to be hold by caller from readside */
1965 int fib_table_dump(struct fib_table *tb, struct sk_buff *skb,
1966                    struct netlink_callback *cb)
1967 {
1968         struct trie *t = (struct trie *)tb->tb_data;
1969         struct key_vector *l, *tp = t->kv;
1970         /* Dump starting at last key.
1971          * Note: 0.0.0.0/0 (ie default) is first key.
1972          */
1973         int count = cb->args[2];
1974         t_key key = cb->args[3];
1975 
1976         while ((l = leaf_walk_rcu(&tp, key)) != NULL) {
1977                 if (fn_trie_dump_leaf(l, tb, skb, cb) < 0) {
1978                         cb->args[3] = key;
1979                         cb->args[2] = count;
1980                         return -1;
1981                 }
1982 
1983                 ++count;
1984                 key = l->key + 1;
1985 
1986                 memset(&cb->args[4], 0,
1987                        sizeof(cb->args) - 4*sizeof(cb->args[0]));
1988 
1989                 /* stop loop if key wrapped back to 0 */
1990                 if (key < l->key)
1991                         break;
1992         }
1993 
1994         cb->args[3] = key;
1995         cb->args[2] = count;
1996 
1997         return skb->len;
1998 }
1999 
2000 void __init fib_trie_init(void)
2001 {
2002         fn_alias_kmem = kmem_cache_create("ip_fib_alias",
2003                                           sizeof(struct fib_alias),
2004                                           0, SLAB_PANIC, NULL);
2005 
2006         trie_leaf_kmem = kmem_cache_create("ip_fib_trie",
2007                                            LEAF_SIZE,
2008                                            0, SLAB_PANIC, NULL);
2009 }
2010 
2011 struct fib_table *fib_trie_table(u32 id, struct fib_table *alias)
2012 {
2013         struct fib_table *tb;
2014         struct trie *t;
2015         size_t sz = sizeof(*tb);
2016 
2017         if (!alias)
2018                 sz += sizeof(struct trie);
2019 
2020         tb = kzalloc(sz, GFP_KERNEL);
2021         if (!tb)
2022                 return NULL;
2023 
2024         tb->tb_id = id;
2025         tb->tb_num_default = 0;
2026         tb->tb_data = (alias ? alias->__data : tb->__data);
2027 
2028         if (alias)
2029                 return tb;
2030 
2031         t = (struct trie *) tb->tb_data;
2032         t->kv[0].pos = KEYLENGTH;
2033         t->kv[0].slen = KEYLENGTH;
2034 #ifdef CONFIG_IP_FIB_TRIE_STATS
2035         t->stats = alloc_percpu(struct trie_use_stats);
2036         if (!t->stats) {
2037                 kfree(tb);
2038                 tb = NULL;
2039         }
2040 #endif
2041 
2042         return tb;
2043 }
2044 
2045 #ifdef CONFIG_PROC_FS
2046 /* Depth first Trie walk iterator */
2047 struct fib_trie_iter {
2048         struct seq_net_private p;
2049         struct fib_table *tb;
2050         struct key_vector *tnode;
2051         unsigned int index;
2052         unsigned int depth;
2053 };
2054 
2055 static struct key_vector *fib_trie_get_next(struct fib_trie_iter *iter)
2056 {
2057         unsigned long cindex = iter->index;
2058         struct key_vector *pn = iter->tnode;
2059         t_key pkey;
2060 
2061         pr_debug("get_next iter={node=%p index=%d depth=%d}\n",
2062                  iter->tnode, iter->index, iter->depth);
2063 
2064         while (!IS_TRIE(pn)) {
2065                 while (cindex < child_length(pn)) {
2066                         struct key_vector *n = get_child_rcu(pn, cindex++);
2067 
2068                         if (!n)
2069                                 continue;
2070 
2071                         if (IS_LEAF(n)) {
2072                                 iter->tnode = pn;
2073                                 iter->index = cindex;
2074                         } else {
2075                                 /* push down one level */
2076                                 iter->tnode = n;
2077                                 iter->index = 0;
2078                                 ++iter->depth;
2079                         }
2080 
2081                         return n;
2082                 }
2083 
2084                 /* Current node exhausted, pop back up */
2085                 pkey = pn->key;
2086                 pn = node_parent_rcu(pn);
2087                 cindex = get_index(pkey, pn) + 1;
2088                 --iter->depth;
2089         }
2090 
2091         /* record root node so further searches know we are done */
2092         iter->tnode = pn;
2093         iter->index = 0;
2094 
2095         return NULL;
2096 }
2097 
2098 static struct key_vector *fib_trie_get_first(struct fib_trie_iter *iter,
2099                                              struct trie *t)
2100 {
2101         struct key_vector *n, *pn;
2102 
2103         if (!t)
2104                 return NULL;
2105 
2106         pn = t->kv;
2107         n = rcu_dereference(pn->tnode[0]);
2108         if (!n)
2109                 return NULL;
2110 
2111         if (IS_TNODE(n)) {
2112                 iter->tnode = n;
2113                 iter->index = 0;
2114                 iter->depth = 1;
2115         } else {
2116                 iter->tnode = pn;
2117                 iter->index = 0;
2118                 iter->depth = 0;
2119         }
2120 
2121         return n;
2122 }
2123 
2124 static void trie_collect_stats(struct trie *t, struct trie_stat *s)
2125 {
2126         struct key_vector *n;
2127         struct fib_trie_iter iter;
2128 
2129         memset(s, 0, sizeof(*s));
2130 
2131         rcu_read_lock();
2132         for (n = fib_trie_get_first(&iter, t); n; n = fib_trie_get_next(&iter)) {
2133                 if (IS_LEAF(n)) {
2134                         struct fib_alias *fa;
2135 
2136                         s->leaves++;
2137                         s->totdepth += iter.depth;
2138                         if (iter.depth > s->maxdepth)
2139                                 s->maxdepth = iter.depth;
2140 
2141                         hlist_for_each_entry_rcu(fa, &n->leaf, fa_list)
2142                                 ++s->prefixes;
2143                 } else {
2144                         s->tnodes++;
2145                         if (n->bits < MAX_STAT_DEPTH)
2146                                 s->nodesizes[n->bits]++;
2147                         s->nullpointers += tn_info(n)->empty_children;
2148                 }
2149         }
2150         rcu_read_unlock();
2151 }
2152 
2153 /*
2154  *      This outputs /proc/net/fib_triestats
2155  */
2156 static void trie_show_stats(struct seq_file *seq, struct trie_stat *stat)
2157 {
2158         unsigned int i, max, pointers, bytes, avdepth;
2159 
2160         if (stat->leaves)
2161                 avdepth = stat->totdepth*100 / stat->leaves;
2162         else
2163                 avdepth = 0;
2164 
2165         seq_printf(seq, "\tAver depth:     %u.%02d\n",
2166                    avdepth / 100, avdepth % 100);
2167         seq_printf(seq, "\tMax depth:      %u\n", stat->maxdepth);
2168 
2169         seq_printf(seq, "\tLeaves:         %u\n", stat->leaves);
2170         bytes = LEAF_SIZE * stat->leaves;
2171 
2172         seq_printf(seq, "\tPrefixes:       %u\n", stat->prefixes);
2173         bytes += sizeof(struct fib_alias) * stat->prefixes;
2174 
2175         seq_printf(seq, "\tInternal nodes: %u\n\t", stat->tnodes);
2176         bytes += TNODE_SIZE(0) * stat->tnodes;
2177 
2178         max = MAX_STAT_DEPTH;
2179         while (max > 0 && stat->nodesizes[max-1] == 0)
2180                 max--;
2181 
2182         pointers = 0;
2183         for (i = 1; i < max; i++)
2184                 if (stat->nodesizes[i] != 0) {
2185                         seq_printf(seq, "  %u: %u",  i, stat->nodesizes[i]);
2186                         pointers += (1<<i) * stat->nodesizes[i];
2187                 }
2188         seq_putc(seq, '\n');
2189         seq_printf(seq, "\tPointers: %u\n", pointers);
2190 
2191         bytes += sizeof(struct key_vector *) * pointers;
2192         seq_printf(seq, "Null ptrs: %u\n", stat->nullpointers);
2193         seq_printf(seq, "Total size: %u  kB\n", (bytes + 1023) / 1024);
2194 }
2195 
2196 #ifdef CONFIG_IP_FIB_TRIE_STATS
2197 static void trie_show_usage(struct seq_file *seq,
2198                             const struct trie_use_stats __percpu *stats)
2199 {
2200         struct trie_use_stats s = { 0 };
2201         int cpu;
2202 
2203         /* loop through all of the CPUs and gather up the stats */
2204         for_each_possible_cpu(cpu) {
2205                 const struct trie_use_stats *pcpu = per_cpu_ptr(stats, cpu);
2206 
2207                 s.gets += pcpu->gets;
2208                 s.backtrack += pcpu->backtrack;
2209                 s.semantic_match_passed += pcpu->semantic_match_passed;
2210                 s.semantic_match_miss += pcpu->semantic_match_miss;
2211                 s.null_node_hit += pcpu->null_node_hit;
2212                 s.resize_node_skipped += pcpu->resize_node_skipped;
2213         }
2214 
2215         seq_printf(seq, "\nCounters:\n---------\n");
2216         seq_printf(seq, "gets = %u\n", s.gets);
2217         seq_printf(seq, "backtracks = %u\n", s.backtrack);
2218         seq_printf(seq, "semantic match passed = %u\n",
2219                    s.semantic_match_passed);
2220         seq_printf(seq, "semantic match miss = %u\n", s.semantic_match_miss);
2221         seq_printf(seq, "null node hit= %u\n", s.null_node_hit);
2222         seq_printf(seq, "skipped node resize = %u\n\n", s.resize_node_skipped);
2223 }
2224 #endif /*  CONFIG_IP_FIB_TRIE_STATS */
2225 
2226 static void fib_table_print(struct seq_file *seq, struct fib_table *tb)
2227 {
2228         if (tb->tb_id == RT_TABLE_LOCAL)
2229                 seq_puts(seq, "Local:\n");
2230         else if (tb->tb_id == RT_TABLE_MAIN)
2231                 seq_puts(seq, "Main:\n");
2232         else
2233                 seq_printf(seq, "Id %d:\n", tb->tb_id);
2234 }
2235 
2236 
2237 static int fib_triestat_seq_show(struct seq_file *seq, void *v)
2238 {
2239         struct net *net = (struct net *)seq->private;
2240         unsigned int h;
2241 
2242         seq_printf(seq,
2243                    "Basic info: size of leaf:"
2244                    " %Zd bytes, size of tnode: %Zd bytes.\n",
2245                    LEAF_SIZE, TNODE_SIZE(0));
2246 
2247         for (h = 0; h < FIB_TABLE_HASHSZ; h++) {
2248                 struct hlist_head *head = &net->ipv4.fib_table_hash[h];
2249                 struct fib_table *tb;
2250 
2251                 hlist_for_each_entry_rcu(tb, head, tb_hlist) {
2252                         struct trie *t = (struct trie *) tb->tb_data;
2253                         struct trie_stat stat;
2254 
2255                         if (!t)
2256                                 continue;
2257 
2258                         fib_table_print(seq, tb);
2259 
2260                         trie_collect_stats(t, &stat);
2261                         trie_show_stats(seq, &stat);
2262 #ifdef CONFIG_IP_FIB_TRIE_STATS
2263                         trie_show_usage(seq, t->stats);
2264 #endif
2265                 }
2266         }
2267 
2268         return 0;
2269 }
2270 
2271 static int fib_triestat_seq_open(struct inode *inode, struct file *file)
2272 {
2273         return single_open_net(inode, file, fib_triestat_seq_show);
2274 }
2275 
2276 static const struct file_operations fib_triestat_fops = {
2277         .owner  = THIS_MODULE,
2278         .open   = fib_triestat_seq_open,
2279         .read   = seq_read,
2280         .llseek = seq_lseek,
2281         .release = single_release_net,
2282 };
2283 
2284 static struct key_vector *fib_trie_get_idx(struct seq_file *seq, loff_t pos)
2285 {
2286         struct fib_trie_iter *iter = seq->private;
2287         struct net *net = seq_file_net(seq);
2288         loff_t idx = 0;
2289         unsigned int h;
2290 
2291         for (h = 0; h < FIB_TABLE_HASHSZ; h++) {
2292                 struct hlist_head *head = &net->ipv4.fib_table_hash[h];
2293                 struct fib_table *tb;
2294 
2295                 hlist_for_each_entry_rcu(tb, head, tb_hlist) {
2296                         struct key_vector *n;
2297 
2298                         for (n = fib_trie_get_first(iter,
2299                                                     (struct trie *) tb->tb_data);
2300                              n; n = fib_trie_get_next(iter))
2301                                 if (pos == idx++) {
2302                                         iter->tb = tb;
2303                                         return n;
2304                                 }
2305                 }
2306         }
2307 
2308         return NULL;
2309 }
2310 
2311 static void *fib_trie_seq_start(struct seq_file *seq, loff_t *pos)
2312         __acquires(RCU)
2313 {
2314         rcu_read_lock();
2315         return fib_trie_get_idx(seq, *pos);
2316 }
2317 
2318 static void *fib_trie_seq_next(struct seq_file *seq, void *v, loff_t *pos)
2319 {
2320         struct fib_trie_iter *iter = seq->private;
2321         struct net *net = seq_file_net(seq);
2322         struct fib_table *tb = iter->tb;
2323         struct hlist_node *tb_node;
2324         unsigned int h;
2325         struct key_vector *n;
2326 
2327         ++*pos;
2328         /* next node in same table */
2329         n = fib_trie_get_next(iter);
2330         if (n)
2331                 return n;
2332 
2333         /* walk rest of this hash chain */
2334         h = tb->tb_id & (FIB_TABLE_HASHSZ - 1);
2335         while ((tb_node = rcu_dereference(hlist_next_rcu(&tb->tb_hlist)))) {
2336                 tb = hlist_entry(tb_node, struct fib_table, tb_hlist);
2337                 n = fib_trie_get_first(iter, (struct trie *) tb->tb_data);
2338                 if (n)
2339                         goto found;
2340         }
2341 
2342         /* new hash chain */
2343         while (++h < FIB_TABLE_HASHSZ) {
2344                 struct hlist_head *head = &net->ipv4.fib_table_hash[h];
2345                 hlist_for_each_entry_rcu(tb, head, tb_hlist) {
2346                         n = fib_trie_get_first(iter, (struct trie *) tb->tb_data);
2347                         if (n)
2348                                 goto found;
2349                 }
2350         }
2351         return NULL;
2352 
2353 found:
2354         iter->tb = tb;
2355         return n;
2356 }
2357 
2358 static void fib_trie_seq_stop(struct seq_file *seq, void *v)
2359         __releases(RCU)
2360 {
2361         rcu_read_unlock();
2362 }
2363 
2364 static void seq_indent(struct seq_file *seq, int n)
2365 {
2366         while (n-- > 0)
2367                 seq_puts(seq, "   ");
2368 }
2369 
2370 static inline const char *rtn_scope(char *buf, size_t len, enum rt_scope_t s)
2371 {
2372         switch (s) {
2373         case RT_SCOPE_UNIVERSE: return "universe";
2374         case RT_SCOPE_SITE:     return "site";
2375         case RT_SCOPE_LINK:     return "link";
2376         case RT_SCOPE_HOST:     return "host";
2377         case RT_SCOPE_NOWHERE:  return "nowhere";
2378         default:
2379                 snprintf(buf, len, "scope=%d", s);
2380                 return buf;
2381         }
2382 }
2383 
2384 static const char *const rtn_type_names[__RTN_MAX] = {
2385         [RTN_UNSPEC] = "UNSPEC",
2386         [RTN_UNICAST] = "UNICAST",
2387         [RTN_LOCAL] = "LOCAL",
2388         [RTN_BROADCAST] = "BROADCAST",
2389         [RTN_ANYCAST] = "ANYCAST",
2390         [RTN_MULTICAST] = "MULTICAST",
2391         [RTN_BLACKHOLE] = "BLACKHOLE",
2392         [RTN_UNREACHABLE] = "UNREACHABLE",
2393         [RTN_PROHIBIT] = "PROHIBIT",
2394         [RTN_THROW] = "THROW",
2395         [RTN_NAT] = "NAT",
2396         [RTN_XRESOLVE] = "XRESOLVE",
2397 };
2398 
2399 static inline const char *rtn_type(char *buf, size_t len, unsigned int t)
2400 {
2401         if (t < __RTN_MAX && rtn_type_names[t])
2402                 return rtn_type_names[t];
2403         snprintf(buf, len, "type %u", t);
2404         return buf;
2405 }
2406 
2407 /* Pretty print the trie */
2408 static int fib_trie_seq_show(struct seq_file *seq, void *v)
2409 {
2410         const struct fib_trie_iter *iter = seq->private;
2411         struct key_vector *n = v;
2412 
2413         if (IS_TRIE(node_parent_rcu(n)))
2414                 fib_table_print(seq, iter->tb);
2415 
2416         if (IS_TNODE(n)) {
2417                 __be32 prf = htonl(n->key);
2418 
2419                 seq_indent(seq, iter->depth-1);
2420                 seq_printf(seq, "  +-- %pI4/%zu %u %u %u\n",
2421                            &prf, KEYLENGTH - n->pos - n->bits, n->bits,
2422                            tn_info(n)->full_children,
2423                            tn_info(n)->empty_children);
2424         } else {
2425                 __be32 val = htonl(n->key);
2426                 struct fib_alias *fa;
2427 
2428                 seq_indent(seq, iter->depth);
2429                 seq_printf(seq, "  |-- %pI4\n", &val);
2430 
2431                 hlist_for_each_entry_rcu(fa, &n->leaf, fa_list) {
2432                         char buf1[32], buf2[32];
2433 
2434                         seq_indent(seq, iter->depth + 1);
2435                         seq_printf(seq, "  /%zu %s %s",
2436                                    KEYLENGTH - fa->fa_slen,
2437                                    rtn_scope(buf1, sizeof(buf1),
2438                                              fa->fa_info->fib_scope),
2439                                    rtn_type(buf2, sizeof(buf2),
2440                                             fa->fa_type));
2441                         if (fa->fa_tos)
2442                                 seq_printf(seq, " tos=%d", fa->fa_tos);
2443                         seq_putc(seq, '\n');
2444                 }
2445         }
2446 
2447         return 0;
2448 }
2449 
2450 static const struct seq_operations fib_trie_seq_ops = {
2451         .start  = fib_trie_seq_start,
2452         .next   = fib_trie_seq_next,
2453         .stop   = fib_trie_seq_stop,
2454         .show   = fib_trie_seq_show,
2455 };
2456 
2457 static int fib_trie_seq_open(struct inode *inode, struct file *file)
2458 {
2459         return seq_open_net(inode, file, &fib_trie_seq_ops,
2460                             sizeof(struct fib_trie_iter));
2461 }
2462 
2463 static const struct file_operations fib_trie_fops = {
2464         .owner  = THIS_MODULE,
2465         .open   = fib_trie_seq_open,
2466         .read   = seq_read,
2467         .llseek = seq_lseek,
2468         .release = seq_release_net,
2469 };
2470 
2471 struct fib_route_iter {
2472         struct seq_net_private p;
2473         struct fib_table *main_tb;
2474         struct key_vector *tnode;
2475         loff_t  pos;
2476         t_key   key;
2477 };
2478 
2479 static struct key_vector *fib_route_get_idx(struct fib_route_iter *iter,
2480                                             loff_t pos)
2481 {
2482         struct key_vector *l, **tp = &iter->tnode;
2483         t_key key;
2484 
2485         /* use cached location of previously found key */
2486         if (iter->pos > 0 && pos >= iter->pos) {
2487                 key = iter->key;
2488         } else {
2489                 iter->pos = 1;
2490                 key = 0;
2491         }
2492 
2493         pos -= iter->pos;
2494 
2495         while ((l = leaf_walk_rcu(tp, key)) && (pos-- > 0)) {
2496                 key = l->key + 1;
2497                 iter->pos++;
2498                 l = NULL;
2499 
2500                 /* handle unlikely case of a key wrap */
2501                 if (!key)
2502                         break;
2503         }
2504 
2505         if (l)
2506                 iter->key = l->key;     /* remember it */
2507         else
2508                 iter->pos = 0;          /* forget it */
2509 
2510         return l;
2511 }
2512 
2513 static void *fib_route_seq_start(struct seq_file *seq, loff_t *pos)
2514         __acquires(RCU)
2515 {
2516         struct fib_route_iter *iter = seq->private;
2517         struct fib_table *tb;
2518         struct trie *t;
2519 
2520         rcu_read_lock();
2521 
2522         tb = fib_get_table(seq_file_net(seq), RT_TABLE_MAIN);
2523         if (!tb)
2524                 return NULL;
2525 
2526         iter->main_tb = tb;
2527         t = (struct trie *)tb->tb_data;
2528         iter->tnode = t->kv;
2529 
2530         if (*pos != 0)
2531                 return fib_route_get_idx(iter, *pos);
2532 
2533         iter->pos = 0;
2534         iter->key = KEY_MAX;
2535 
2536         return SEQ_START_TOKEN;
2537 }
2538 
2539 static void *fib_route_seq_next(struct seq_file *seq, void *v, loff_t *pos)
2540 {
2541         struct fib_route_iter *iter = seq->private;
2542         struct key_vector *l = NULL;
2543         t_key key = iter->key + 1;
2544 
2545         ++*pos;
2546 
2547         /* only allow key of 0 for start of sequence */
2548         if ((v == SEQ_START_TOKEN) || key)
2549                 l = leaf_walk_rcu(&iter->tnode, key);
2550 
2551         if (l) {
2552                 iter->key = l->key;
2553                 iter->pos++;
2554         } else {
2555                 iter->pos = 0;
2556         }
2557 
2558         return l;
2559 }
2560 
2561 static void fib_route_seq_stop(struct seq_file *seq, void *v)
2562         __releases(RCU)
2563 {
2564         rcu_read_unlock();
2565 }
2566 
2567 static unsigned int fib_flag_trans(int type, __be32 mask, const struct fib_info *fi)
2568 {
2569         unsigned int flags = 0;
2570 
2571         if (type == RTN_UNREACHABLE || type == RTN_PROHIBIT)
2572                 flags = RTF_REJECT;
2573         if (fi && fi->fib_nh->nh_gw)
2574                 flags |= RTF_GATEWAY;
2575         if (mask == htonl(0xFFFFFFFF))
2576                 flags |= RTF_HOST;
2577         flags |= RTF_UP;
2578         return flags;
2579 }
2580 
2581 /*
2582  *      This outputs /proc/net/route.
2583  *      The format of the file is not supposed to be changed
2584  *      and needs to be same as fib_hash output to avoid breaking
2585  *      legacy utilities
2586  */
2587 static int fib_route_seq_show(struct seq_file *seq, void *v)
2588 {
2589         struct fib_route_iter *iter = seq->private;
2590         struct fib_table *tb = iter->main_tb;
2591         struct fib_alias *fa;
2592         struct key_vector *l = v;
2593         __be32 prefix;
2594 
2595         if (v == SEQ_START_TOKEN) {
2596                 seq_printf(seq, "%-127s\n", "Iface\tDestination\tGateway "
2597                            "\tFlags\tRefCnt\tUse\tMetric\tMask\t\tMTU"
2598                            "\tWindow\tIRTT");
2599                 return 0;
2600         }
2601 
2602         prefix = htonl(l->key);
2603 
2604         hlist_for_each_entry_rcu(fa, &l->leaf, fa_list) {
2605                 const struct fib_info *fi = fa->fa_info;
2606                 __be32 mask = inet_make_mask(KEYLENGTH - fa->fa_slen);
2607                 unsigned int flags = fib_flag_trans(fa->fa_type, mask, fi);
2608 
2609                 if ((fa->fa_type == RTN_BROADCAST) ||
2610                     (fa->fa_type == RTN_MULTICAST))
2611                         continue;
2612 
2613                 if (fa->tb_id != tb->tb_id)
2614                         continue;
2615 
2616                 seq_setwidth(seq, 127);
2617 
2618                 if (fi)
2619                         seq_printf(seq,
2620                                    "%s\t%08X\t%08X\t%04X\t%d\t%u\t"
2621                                    "%d\t%08X\t%d\t%u\t%u",
2622                                    fi->fib_dev ? fi->fib_dev->name : "*",
2623                                    prefix,
2624                                    fi->fib_nh->nh_gw, flags, 0, 0,
2625                                    fi->fib_priority,
2626                                    mask,
2627                                    (fi->fib_advmss ?
2628                                     fi->fib_advmss + 40 : 0),
2629                                    fi->fib_window,
2630                                    fi->fib_rtt >> 3);
2631                 else
2632                         seq_printf(seq,
2633                                    "*\t%08X\t%08X\t%04X\t%d\t%u\t"
2634                                    "%d\t%08X\t%d\t%u\t%u",
2635                                    prefix, 0, flags, 0, 0, 0,
2636                                    mask, 0, 0, 0);
2637 
2638                 seq_pad(seq, '\n');
2639         }
2640 
2641         return 0;
2642 }
2643 
2644 static const struct seq_operations fib_route_seq_ops = {
2645         .start  = fib_route_seq_start,
2646         .next   = fib_route_seq_next,
2647         .stop   = fib_route_seq_stop,
2648         .show   = fib_route_seq_show,
2649 };
2650 
2651 static int fib_route_seq_open(struct inode *inode, struct file *file)
2652 {
2653         return seq_open_net(inode, file, &fib_route_seq_ops,
2654                             sizeof(struct fib_route_iter));
2655 }
2656 
2657 static const struct file_operations fib_route_fops = {
2658         .owner  = THIS_MODULE,
2659         .open   = fib_route_seq_open,
2660         .read   = seq_read,
2661         .llseek = seq_lseek,
2662         .release = seq_release_net,
2663 };
2664 
2665 int __net_init fib_proc_init(struct net *net)
2666 {
2667         if (!proc_create("fib_trie", S_IRUGO, net->proc_net, &fib_trie_fops))
2668                 goto out1;
2669 
2670         if (!proc_create("fib_triestat", S_IRUGO, net->proc_net,
2671                          &fib_triestat_fops))
2672                 goto out2;
2673 
2674         if (!proc_create("route", S_IRUGO, net->proc_net, &fib_route_fops))
2675                 goto out3;
2676 
2677         return 0;
2678 
2679 out3:
2680         remove_proc_entry("fib_triestat", net->proc_net);
2681 out2:
2682         remove_proc_entry("fib_trie", net->proc_net);
2683 out1:
2684         return -ENOMEM;
2685 }
2686 
2687 void __net_exit fib_proc_exit(struct net *net)
2688 {
2689         remove_proc_entry("fib_trie", net->proc_net);
2690         remove_proc_entry("fib_triestat", net->proc_net);
2691         remove_proc_entry("route", net->proc_net);
2692 }
2693 
2694 #endif /* CONFIG_PROC_FS */
2695 

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