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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 <net/net_namespace.h>
 77 #include <net/ip.h>
 78 #include <net/protocol.h>
 79 #include <net/route.h>
 80 #include <net/tcp.h>
 81 #include <net/sock.h>
 82 #include <net/ip_fib.h>
 83 #include <net/switchdev.h>
 84 #include <trace/events/fib.h>
 85 #include "fib_lookup.h"
 86 
 87 #define MAX_STAT_DEPTH 32
 88 
 89 #define KEYLENGTH       (8*sizeof(t_key))
 90 #define KEY_MAX         ((t_key)~0)
 91 
 92 typedef unsigned int t_key;
 93 
 94 #define IS_TRIE(n)      ((n)->pos >= KEYLENGTH)
 95 #define IS_TNODE(n)     ((n)->bits)
 96 #define IS_LEAF(n)      (!(n)->bits)
 97 
 98 struct key_vector {
 99         t_key key;
100         unsigned char pos;              /* 2log(KEYLENGTH) bits needed */
101         unsigned char bits;             /* 2log(KEYLENGTH) bits needed */
102         unsigned char slen;
103         union {
104                 /* This list pointer if valid if (pos | bits) == 0 (LEAF) */
105                 struct hlist_head leaf;
106                 /* This array is valid if (pos | bits) > 0 (TNODE) */
107                 struct key_vector __rcu *tnode[0];
108         };
109 };
110 
111 struct tnode {
112         struct rcu_head rcu;
113         t_key empty_children;           /* KEYLENGTH bits needed */
114         t_key full_children;            /* KEYLENGTH bits needed */
115         struct key_vector __rcu *parent;
116         struct key_vector kv[1];
117 #define tn_bits kv[0].bits
118 };
119 
120 #define TNODE_SIZE(n)   offsetof(struct tnode, kv[0].tnode[n])
121 #define LEAF_SIZE       TNODE_SIZE(1)
122 
123 #ifdef CONFIG_IP_FIB_TRIE_STATS
124 struct trie_use_stats {
125         unsigned int gets;
126         unsigned int backtrack;
127         unsigned int semantic_match_passed;
128         unsigned int semantic_match_miss;
129         unsigned int null_node_hit;
130         unsigned int resize_node_skipped;
131 };
132 #endif
133 
134 struct trie_stat {
135         unsigned int totdepth;
136         unsigned int maxdepth;
137         unsigned int tnodes;
138         unsigned int leaves;
139         unsigned int nullpointers;
140         unsigned int prefixes;
141         unsigned int nodesizes[MAX_STAT_DEPTH];
142 };
143 
144 struct trie {
145         struct key_vector kv[1];
146 #ifdef CONFIG_IP_FIB_TRIE_STATS
147         struct trie_use_stats __percpu *stats;
148 #endif
149 };
150 
151 static struct key_vector *resize(struct trie *t, struct key_vector *tn);
152 static size_t tnode_free_size;
153 
154 /*
155  * synchronize_rcu after call_rcu for that many pages; it should be especially
156  * useful before resizing the root node with PREEMPT_NONE configs; the value was
157  * obtained experimentally, aiming to avoid visible slowdown.
158  */
159 static const int sync_pages = 128;
160 
161 static struct kmem_cache *fn_alias_kmem __read_mostly;
162 static struct kmem_cache *trie_leaf_kmem __read_mostly;
163 
164 static inline struct tnode *tn_info(struct key_vector *kv)
165 {
166         return container_of(kv, struct tnode, kv[0]);
167 }
168 
169 /* caller must hold RTNL */
170 #define node_parent(tn) rtnl_dereference(tn_info(tn)->parent)
171 #define get_child(tn, i) rtnl_dereference((tn)->tnode[i])
172 
173 /* caller must hold RCU read lock or RTNL */
174 #define node_parent_rcu(tn) rcu_dereference_rtnl(tn_info(tn)->parent)
175 #define get_child_rcu(tn, i) rcu_dereference_rtnl((tn)->tnode[i])
176 
177 /* wrapper for rcu_assign_pointer */
178 static inline void node_set_parent(struct key_vector *n, struct key_vector *tp)
179 {
180         if (n)
181                 rcu_assign_pointer(tn_info(n)->parent, tp);
182 }
183 
184 #define NODE_INIT_PARENT(n, p) RCU_INIT_POINTER(tn_info(n)->parent, p)
185 
186 /* This provides us with the number of children in this node, in the case of a
187  * leaf this will return 0 meaning none of the children are accessible.
188  */
189 static inline unsigned long child_length(const struct key_vector *tn)
190 {
191         return (1ul << tn->bits) & ~(1ul);
192 }
193 
194 #define get_cindex(key, kv) (((key) ^ (kv)->key) >> (kv)->pos)
195 
196 static inline unsigned long get_index(t_key key, struct key_vector *kv)
197 {
198         unsigned long index = key ^ kv->key;
199 
200         if ((BITS_PER_LONG <= KEYLENGTH) && (KEYLENGTH == kv->pos))
201                 return 0;
202 
203         return index >> kv->pos;
204 }
205 
206 /* To understand this stuff, an understanding of keys and all their bits is
207  * necessary. Every node in the trie has a key associated with it, but not
208  * all of the bits in that key are significant.
209  *
210  * Consider a node 'n' and its parent 'tp'.
211  *
212  * If n is a leaf, every bit in its key is significant. Its presence is
213  * necessitated by path compression, since during a tree traversal (when
214  * searching for a leaf - unless we are doing an insertion) we will completely
215  * ignore all skipped bits we encounter. Thus we need to verify, at the end of
216  * a potentially successful search, that we have indeed been walking the
217  * correct key path.
218  *
219  * Note that we can never "miss" the correct key in the tree if present by
220  * following the wrong path. Path compression ensures that segments of the key
221  * that are the same for all keys with a given prefix are skipped, but the
222  * skipped part *is* identical for each node in the subtrie below the skipped
223  * bit! trie_insert() in this implementation takes care of that.
224  *
225  * if n is an internal node - a 'tnode' here, the various parts of its key
226  * have many different meanings.
227  *
228  * Example:
229  * _________________________________________________________________
230  * | i | i | i | i | i | i | i | N | N | N | S | S | S | S | S | C |
231  * -----------------------------------------------------------------
232  *  31  30  29  28  27  26  25  24  23  22  21  20  19  18  17  16
233  *
234  * _________________________________________________________________
235  * | C | C | C | u | u | u | u | u | u | u | u | u | u | u | u | u |
236  * -----------------------------------------------------------------
237  *  15  14  13  12  11  10   9   8   7   6   5   4   3   2   1   0
238  *
239  * tp->pos = 22
240  * tp->bits = 3
241  * n->pos = 13
242  * n->bits = 4
243  *
244  * First, let's just ignore the bits that come before the parent tp, that is
245  * the bits from (tp->pos + tp->bits) to 31. They are *known* but at this
246  * point we do not use them for anything.
247  *
248  * The bits from (tp->pos) to (tp->pos + tp->bits - 1) - "N", above - are the
249  * index into the parent's child array. That is, they will be used to find
250  * 'n' among tp's children.
251  *
252  * The bits from (n->pos + n->bits) to (tn->pos - 1) - "S" - are skipped bits
253  * for the node n.
254  *
255  * All the bits we have seen so far are significant to the node n. The rest
256  * of the bits are really not needed or indeed known in n->key.
257  *
258  * The bits from (n->pos) to (n->pos + n->bits - 1) - "C" - are the index into
259  * n's child array, and will of course be different for each child.
260  *
261  * The rest of the bits, from 0 to (n->pos + n->bits), are completely unknown
262  * at this point.
263  */
264 
265 static const int halve_threshold = 25;
266 static const int inflate_threshold = 50;
267 static const int halve_threshold_root = 15;
268 static const int inflate_threshold_root = 30;
269 
270 static void __alias_free_mem(struct rcu_head *head)
271 {
272         struct fib_alias *fa = container_of(head, struct fib_alias, rcu);
273         kmem_cache_free(fn_alias_kmem, fa);
274 }
275 
276 static inline void alias_free_mem_rcu(struct fib_alias *fa)
277 {
278         call_rcu(&fa->rcu, __alias_free_mem);
279 }
280 
281 #define TNODE_KMALLOC_MAX \
282         ilog2((PAGE_SIZE - TNODE_SIZE(0)) / sizeof(struct key_vector *))
283 #define TNODE_VMALLOC_MAX \
284         ilog2((SIZE_MAX - TNODE_SIZE(0)) / sizeof(struct key_vector *))
285 
286 static void __node_free_rcu(struct rcu_head *head)
287 {
288         struct tnode *n = container_of(head, struct tnode, rcu);
289 
290         if (!n->tn_bits)
291                 kmem_cache_free(trie_leaf_kmem, n);
292         else
293                 kvfree(n);
294 }
295 
296 #define node_free(n) call_rcu(&tn_info(n)->rcu, __node_free_rcu)
297 
298 static struct tnode *tnode_alloc(int bits)
299 {
300         size_t size;
301 
302         /* verify bits is within bounds */
303         if (bits > TNODE_VMALLOC_MAX)
304                 return NULL;
305 
306         /* determine size and verify it is non-zero and didn't overflow */
307         size = TNODE_SIZE(1ul << bits);
308 
309         if (size <= PAGE_SIZE)
310                 return kzalloc(size, GFP_KERNEL);
311         else
312                 return vzalloc(size);
313 }
314 
315 static inline void empty_child_inc(struct key_vector *n)
316 {
317         ++tn_info(n)->empty_children ? : ++tn_info(n)->full_children;
318 }
319 
320 static inline void empty_child_dec(struct key_vector *n)
321 {
322         tn_info(n)->empty_children-- ? : tn_info(n)->full_children--;
323 }
324 
325 static struct key_vector *leaf_new(t_key key, struct fib_alias *fa)
326 {
327         struct key_vector *l;
328         struct tnode *kv;
329 
330         kv = kmem_cache_alloc(trie_leaf_kmem, GFP_KERNEL);
331         if (!kv)
332                 return NULL;
333 
334         /* initialize key vector */
335         l = kv->kv;
336         l->key = key;
337         l->pos = 0;
338         l->bits = 0;
339         l->slen = fa->fa_slen;
340 
341         /* link leaf to fib alias */
342         INIT_HLIST_HEAD(&l->leaf);
343         hlist_add_head(&fa->fa_list, &l->leaf);
344 
345         return l;
346 }
347 
348 static struct key_vector *tnode_new(t_key key, int pos, int bits)
349 {
350         unsigned int shift = pos + bits;
351         struct key_vector *tn;
352         struct tnode *tnode;
353 
354         /* verify bits and pos their msb bits clear and values are valid */
355         BUG_ON(!bits || (shift > KEYLENGTH));
356 
357         tnode = tnode_alloc(bits);
358         if (!tnode)
359                 return NULL;
360 
361         pr_debug("AT %p s=%zu %zu\n", tnode, TNODE_SIZE(0),
362                  sizeof(struct key_vector *) << bits);
363 
364         if (bits == KEYLENGTH)
365                 tnode->full_children = 1;
366         else
367                 tnode->empty_children = 1ul << bits;
368 
369         tn = tnode->kv;
370         tn->key = (shift < KEYLENGTH) ? (key >> shift) << shift : 0;
371         tn->pos = pos;
372         tn->bits = bits;
373         tn->slen = pos;
374 
375         return tn;
376 }
377 
378 /* Check whether a tnode 'n' is "full", i.e. it is an internal node
379  * and no bits are skipped. See discussion in dyntree paper p. 6
380  */
381 static inline int tnode_full(struct key_vector *tn, struct key_vector *n)
382 {
383         return n && ((n->pos + n->bits) == tn->pos) && IS_TNODE(n);
384 }
385 
386 /* Add a child at position i overwriting the old value.
387  * Update the value of full_children and empty_children.
388  */
389 static void put_child(struct key_vector *tn, unsigned long i,
390                       struct key_vector *n)
391 {
392         struct key_vector *chi = get_child(tn, i);
393         int isfull, wasfull;
394 
395         BUG_ON(i >= child_length(tn));
396 
397         /* update emptyChildren, overflow into fullChildren */
398         if (!n && chi)
399                 empty_child_inc(tn);
400         if (n && !chi)
401                 empty_child_dec(tn);
402 
403         /* update fullChildren */
404         wasfull = tnode_full(tn, chi);
405         isfull = tnode_full(tn, n);
406 
407         if (wasfull && !isfull)
408                 tn_info(tn)->full_children--;
409         else if (!wasfull && isfull)
410                 tn_info(tn)->full_children++;
411 
412         if (n && (tn->slen < n->slen))
413                 tn->slen = n->slen;
414 
415         rcu_assign_pointer(tn->tnode[i], n);
416 }
417 
418 static void update_children(struct key_vector *tn)
419 {
420         unsigned long i;
421 
422         /* update all of the child parent pointers */
423         for (i = child_length(tn); i;) {
424                 struct key_vector *inode = get_child(tn, --i);
425 
426                 if (!inode)
427                         continue;
428 
429                 /* Either update the children of a tnode that
430                  * already belongs to us or update the child
431                  * to point to ourselves.
432                  */
433                 if (node_parent(inode) == tn)
434                         update_children(inode);
435                 else
436                         node_set_parent(inode, tn);
437         }
438 }
439 
440 static inline void put_child_root(struct key_vector *tp, t_key key,
441                                   struct key_vector *n)
442 {
443         if (IS_TRIE(tp))
444                 rcu_assign_pointer(tp->tnode[0], n);
445         else
446                 put_child(tp, get_index(key, tp), n);
447 }
448 
449 static inline void tnode_free_init(struct key_vector *tn)
450 {
451         tn_info(tn)->rcu.next = NULL;
452 }
453 
454 static inline void tnode_free_append(struct key_vector *tn,
455                                      struct key_vector *n)
456 {
457         tn_info(n)->rcu.next = tn_info(tn)->rcu.next;
458         tn_info(tn)->rcu.next = &tn_info(n)->rcu;
459 }
460 
461 static void tnode_free(struct key_vector *tn)
462 {
463         struct callback_head *head = &tn_info(tn)->rcu;
464 
465         while (head) {
466                 head = head->next;
467                 tnode_free_size += TNODE_SIZE(1ul << tn->bits);
468                 node_free(tn);
469 
470                 tn = container_of(head, struct tnode, rcu)->kv;
471         }
472 
473         if (tnode_free_size >= PAGE_SIZE * sync_pages) {
474                 tnode_free_size = 0;
475                 synchronize_rcu();
476         }
477 }
478 
479 static struct key_vector *replace(struct trie *t,
480                                   struct key_vector *oldtnode,
481                                   struct key_vector *tn)
482 {
483         struct key_vector *tp = node_parent(oldtnode);
484         unsigned long i;
485 
486         /* setup the parent pointer out of and back into this node */
487         NODE_INIT_PARENT(tn, tp);
488         put_child_root(tp, tn->key, tn);
489 
490         /* update all of the child parent pointers */
491         update_children(tn);
492 
493         /* all pointers should be clean so we are done */
494         tnode_free(oldtnode);
495 
496         /* resize children now that oldtnode is freed */
497         for (i = child_length(tn); i;) {
498                 struct key_vector *inode = get_child(tn, --i);
499 
500                 /* resize child node */
501                 if (tnode_full(tn, inode))
502                         tn = resize(t, inode);
503         }
504 
505         return tp;
506 }
507 
508 static struct key_vector *inflate(struct trie *t,
509                                   struct key_vector *oldtnode)
510 {
511         struct key_vector *tn;
512         unsigned long i;
513         t_key m;
514 
515         pr_debug("In inflate\n");
516 
517         tn = tnode_new(oldtnode->key, oldtnode->pos - 1, oldtnode->bits + 1);
518         if (!tn)
519                 goto notnode;
520 
521         /* prepare oldtnode to be freed */
522         tnode_free_init(oldtnode);
523 
524         /* Assemble all of the pointers in our cluster, in this case that
525          * represents all of the pointers out of our allocated nodes that
526          * point to existing tnodes and the links between our allocated
527          * nodes.
528          */
529         for (i = child_length(oldtnode), m = 1u << tn->pos; i;) {
530                 struct key_vector *inode = get_child(oldtnode, --i);
531                 struct key_vector *node0, *node1;
532                 unsigned long j, k;
533 
534                 /* An empty child */
535                 if (!inode)
536                         continue;
537 
538                 /* A leaf or an internal node with skipped bits */
539                 if (!tnode_full(oldtnode, inode)) {
540                         put_child(tn, get_index(inode->key, tn), inode);
541                         continue;
542                 }
543 
544                 /* drop the node in the old tnode free list */
545                 tnode_free_append(oldtnode, inode);
546 
547                 /* An internal node with two children */
548                 if (inode->bits == 1) {
549                         put_child(tn, 2 * i + 1, get_child(inode, 1));
550                         put_child(tn, 2 * i, get_child(inode, 0));
551                         continue;
552                 }
553 
554                 /* We will replace this node 'inode' with two new
555                  * ones, 'node0' and 'node1', each with half of the
556                  * original children. The two new nodes will have
557                  * a position one bit further down the key and this
558                  * means that the "significant" part of their keys
559                  * (see the discussion near the top of this file)
560                  * will differ by one bit, which will be "" in
561                  * node0's key and "1" in node1's key. Since we are
562                  * moving the key position by one step, the bit that
563                  * we are moving away from - the bit at position
564                  * (tn->pos) - is the one that will differ between
565                  * node0 and node1. So... we synthesize that bit in the
566                  * two new keys.
567                  */
568                 node1 = tnode_new(inode->key | m, inode->pos, inode->bits - 1);
569                 if (!node1)
570                         goto nomem;
571                 node0 = tnode_new(inode->key, inode->pos, inode->bits - 1);
572 
573                 tnode_free_append(tn, node1);
574                 if (!node0)
575                         goto nomem;
576                 tnode_free_append(tn, node0);
577 
578                 /* populate child pointers in new nodes */
579                 for (k = child_length(inode), j = k / 2; j;) {
580                         put_child(node1, --j, get_child(inode, --k));
581                         put_child(node0, j, get_child(inode, j));
582                         put_child(node1, --j, get_child(inode, --k));
583                         put_child(node0, j, get_child(inode, j));
584                 }
585 
586                 /* link new nodes to parent */
587                 NODE_INIT_PARENT(node1, tn);
588                 NODE_INIT_PARENT(node0, tn);
589 
590                 /* link parent to nodes */
591                 put_child(tn, 2 * i + 1, node1);
592                 put_child(tn, 2 * i, node0);
593         }
594 
595         /* setup the parent pointers into and out of this node */
596         return replace(t, oldtnode, tn);
597 nomem:
598         /* all pointers should be clean so we are done */
599         tnode_free(tn);
600 notnode:
601         return NULL;
602 }
603 
604 static struct key_vector *halve(struct trie *t,
605                                 struct key_vector *oldtnode)
606 {
607         struct key_vector *tn;
608         unsigned long i;
609 
610         pr_debug("In halve\n");
611 
612         tn = tnode_new(oldtnode->key, oldtnode->pos + 1, oldtnode->bits - 1);
613         if (!tn)
614                 goto notnode;
615 
616         /* prepare oldtnode to be freed */
617         tnode_free_init(oldtnode);
618 
619         /* Assemble all of the pointers in our cluster, in this case that
620          * represents all of the pointers out of our allocated nodes that
621          * point to existing tnodes and the links between our allocated
622          * nodes.
623          */
624         for (i = child_length(oldtnode); i;) {
625                 struct key_vector *node1 = get_child(oldtnode, --i);
626                 struct key_vector *node0 = get_child(oldtnode, --i);
627                 struct key_vector *inode;
628 
629                 /* At least one of the children is empty */
630                 if (!node1 || !node0) {
631                         put_child(tn, i / 2, node1 ? : node0);
632                         continue;
633                 }
634 
635                 /* Two nonempty children */
636                 inode = tnode_new(node0->key, oldtnode->pos, 1);
637                 if (!inode)
638                         goto nomem;
639                 tnode_free_append(tn, inode);
640 
641                 /* initialize pointers out of node */
642                 put_child(inode, 1, node1);
643                 put_child(inode, 0, node0);
644                 NODE_INIT_PARENT(inode, tn);
645 
646                 /* link parent to node */
647                 put_child(tn, i / 2, inode);
648         }
649 
650         /* setup the parent pointers into and out of this node */
651         return replace(t, oldtnode, tn);
652 nomem:
653         /* all pointers should be clean so we are done */
654         tnode_free(tn);
655 notnode:
656         return NULL;
657 }
658 
659 static struct key_vector *collapse(struct trie *t,
660                                    struct key_vector *oldtnode)
661 {
662         struct key_vector *n, *tp;
663         unsigned long i;
664 
665         /* scan the tnode looking for that one child that might still exist */
666         for (n = NULL, i = child_length(oldtnode); !n && i;)
667                 n = get_child(oldtnode, --i);
668 
669         /* compress one level */
670         tp = node_parent(oldtnode);
671         put_child_root(tp, oldtnode->key, n);
672         node_set_parent(n, tp);
673 
674         /* drop dead node */
675         node_free(oldtnode);
676 
677         return tp;
678 }
679 
680 static unsigned char update_suffix(struct key_vector *tn)
681 {
682         unsigned char slen = tn->pos;
683         unsigned long stride, i;
684 
685         /* search though the list of children looking for nodes that might
686          * have a suffix greater than the one we currently have.  This is
687          * why we start with a stride of 2 since a stride of 1 would
688          * represent the nodes with suffix length equal to tn->pos
689          */
690         for (i = 0, stride = 0x2ul ; i < child_length(tn); i += stride) {
691                 struct key_vector *n = get_child(tn, i);
692 
693                 if (!n || (n->slen <= slen))
694                         continue;
695 
696                 /* update stride and slen based on new value */
697                 stride <<= (n->slen - slen);
698                 slen = n->slen;
699                 i &= ~(stride - 1);
700 
701                 /* if slen covers all but the last bit we can stop here
702                  * there will be nothing longer than that since only node
703                  * 0 and 1 << (bits - 1) could have that as their suffix
704                  * length.
705                  */
706                 if ((slen + 1) >= (tn->pos + tn->bits))
707                         break;
708         }
709 
710         tn->slen = slen;
711 
712         return slen;
713 }
714 
715 /* From "Implementing a dynamic compressed trie" by Stefan Nilsson of
716  * the Helsinki University of Technology and Matti Tikkanen of Nokia
717  * Telecommunications, page 6:
718  * "A node is doubled if the ratio of non-empty children to all
719  * children in the *doubled* node is at least 'high'."
720  *
721  * 'high' in this instance is the variable 'inflate_threshold'. It
722  * is expressed as a percentage, so we multiply it with
723  * child_length() and instead of multiplying by 2 (since the
724  * child array will be doubled by inflate()) and multiplying
725  * the left-hand side by 100 (to handle the percentage thing) we
726  * multiply the left-hand side by 50.
727  *
728  * The left-hand side may look a bit weird: child_length(tn)
729  * - tn->empty_children is of course the number of non-null children
730  * in the current node. tn->full_children is the number of "full"
731  * children, that is non-null tnodes with a skip value of 0.
732  * All of those will be doubled in the resulting inflated tnode, so
733  * we just count them one extra time here.
734  *
735  * A clearer way to write this would be:
736  *
737  * to_be_doubled = tn->full_children;
738  * not_to_be_doubled = child_length(tn) - tn->empty_children -
739  *     tn->full_children;
740  *
741  * new_child_length = child_length(tn) * 2;
742  *
743  * new_fill_factor = 100 * (not_to_be_doubled + 2*to_be_doubled) /
744  *      new_child_length;
745  * if (new_fill_factor >= inflate_threshold)
746  *
747  * ...and so on, tho it would mess up the while () loop.
748  *
749  * anyway,
750  * 100 * (not_to_be_doubled + 2*to_be_doubled) / new_child_length >=
751  *      inflate_threshold
752  *
753  * avoid a division:
754  * 100 * (not_to_be_doubled + 2*to_be_doubled) >=
755  *      inflate_threshold * new_child_length
756  *
757  * expand not_to_be_doubled and to_be_doubled, and shorten:
758  * 100 * (child_length(tn) - tn->empty_children +
759  *    tn->full_children) >= inflate_threshold * new_child_length
760  *
761  * expand new_child_length:
762  * 100 * (child_length(tn) - tn->empty_children +
763  *    tn->full_children) >=
764  *      inflate_threshold * child_length(tn) * 2
765  *
766  * shorten again:
767  * 50 * (tn->full_children + child_length(tn) -
768  *    tn->empty_children) >= inflate_threshold *
769  *    child_length(tn)
770  *
771  */
772 static inline bool should_inflate(struct key_vector *tp, struct key_vector *tn)
773 {
774         unsigned long used = child_length(tn);
775         unsigned long threshold = used;
776 
777         /* Keep root node larger */
778         threshold *= IS_TRIE(tp) ? inflate_threshold_root : inflate_threshold;
779         used -= tn_info(tn)->empty_children;
780         used += tn_info(tn)->full_children;
781 
782         /* if bits == KEYLENGTH then pos = 0, and will fail below */
783 
784         return (used > 1) && tn->pos && ((50 * used) >= threshold);
785 }
786 
787 static inline bool should_halve(struct key_vector *tp, struct key_vector *tn)
788 {
789         unsigned long used = child_length(tn);
790         unsigned long threshold = used;
791 
792         /* Keep root node larger */
793         threshold *= IS_TRIE(tp) ? halve_threshold_root : halve_threshold;
794         used -= tn_info(tn)->empty_children;
795 
796         /* if bits == KEYLENGTH then used = 100% on wrap, and will fail below */
797 
798         return (used > 1) && (tn->bits > 1) && ((100 * used) < threshold);
799 }
800 
801 static inline bool should_collapse(struct key_vector *tn)
802 {
803         unsigned long used = child_length(tn);
804 
805         used -= tn_info(tn)->empty_children;
806 
807         /* account for bits == KEYLENGTH case */
808         if ((tn->bits == KEYLENGTH) && tn_info(tn)->full_children)
809                 used -= KEY_MAX;
810 
811         /* One child or none, time to drop us from the trie */
812         return used < 2;
813 }
814 
815 #define MAX_WORK 10
816 static struct key_vector *resize(struct trie *t, struct key_vector *tn)
817 {
818 #ifdef CONFIG_IP_FIB_TRIE_STATS
819         struct trie_use_stats __percpu *stats = t->stats;
820 #endif
821         struct key_vector *tp = node_parent(tn);
822         unsigned long cindex = get_index(tn->key, tp);
823         int max_work = MAX_WORK;
824 
825         pr_debug("In tnode_resize %p inflate_threshold=%d threshold=%d\n",
826                  tn, inflate_threshold, halve_threshold);
827 
828         /* track the tnode via the pointer from the parent instead of
829          * doing it ourselves.  This way we can let RCU fully do its
830          * thing without us interfering
831          */
832         BUG_ON(tn != get_child(tp, cindex));
833 
834         /* Double as long as the resulting node has a number of
835          * nonempty nodes that are above the threshold.
836          */
837         while (should_inflate(tp, tn) && max_work) {
838                 tp = inflate(t, tn);
839                 if (!tp) {
840 #ifdef CONFIG_IP_FIB_TRIE_STATS
841                         this_cpu_inc(stats->resize_node_skipped);
842 #endif
843                         break;
844                 }
845 
846                 max_work--;
847                 tn = get_child(tp, cindex);
848         }
849 
850         /* update parent in case inflate failed */
851         tp = node_parent(tn);
852 
853         /* Return if at least one inflate is run */
854         if (max_work != MAX_WORK)
855                 return tp;
856 
857         /* Halve as long as the number of empty children in this
858          * node is above threshold.
859          */
860         while (should_halve(tp, tn) && max_work) {
861                 tp = halve(t, tn);
862                 if (!tp) {
863 #ifdef CONFIG_IP_FIB_TRIE_STATS
864                         this_cpu_inc(stats->resize_node_skipped);
865 #endif
866                         break;
867                 }
868 
869                 max_work--;
870                 tn = get_child(tp, cindex);
871         }
872 
873         /* Only one child remains */
874         if (should_collapse(tn))
875                 return collapse(t, tn);
876 
877         /* update parent in case halve failed */
878         tp = node_parent(tn);
879 
880         /* Return if at least one deflate was run */
881         if (max_work != MAX_WORK)
882                 return tp;
883 
884         /* push the suffix length to the parent node */
885         if (tn->slen > tn->pos) {
886                 unsigned char slen = update_suffix(tn);
887 
888                 if (slen > tp->slen)
889                         tp->slen = slen;
890         }
891 
892         return tp;
893 }
894 
895 static void leaf_pull_suffix(struct key_vector *tp, struct key_vector *l)
896 {
897         while ((tp->slen > tp->pos) && (tp->slen > l->slen)) {
898                 if (update_suffix(tp) > l->slen)
899                         break;
900                 tp = node_parent(tp);
901         }
902 }
903 
904 static void leaf_push_suffix(struct key_vector *tn, struct key_vector *l)
905 {
906         /* if this is a new leaf then tn will be NULL and we can sort
907          * out parent suffix lengths as a part of trie_rebalance
908          */
909         while (tn->slen < l->slen) {
910                 tn->slen = l->slen;
911                 tn = node_parent(tn);
912         }
913 }
914 
915 /* rcu_read_lock needs to be hold by caller from readside */
916 static struct key_vector *fib_find_node(struct trie *t,
917                                         struct key_vector **tp, u32 key)
918 {
919         struct key_vector *pn, *n = t->kv;
920         unsigned long index = 0;
921 
922         do {
923                 pn = n;
924                 n = get_child_rcu(n, index);
925 
926                 if (!n)
927                         break;
928 
929                 index = get_cindex(key, n);
930 
931                 /* This bit of code is a bit tricky but it combines multiple
932                  * checks into a single check.  The prefix consists of the
933                  * prefix plus zeros for the bits in the cindex. The index
934                  * is the difference between the key and this value.  From
935                  * this we can actually derive several pieces of data.
936                  *   if (index >= (1ul << bits))
937                  *     we have a mismatch in skip bits and failed
938                  *   else
939                  *     we know the value is cindex
940                  *
941                  * This check is safe even if bits == KEYLENGTH due to the
942                  * fact that we can only allocate a node with 32 bits if a
943                  * long is greater than 32 bits.
944                  */
945                 if (index >= (1ul << n->bits)) {
946                         n = NULL;
947                         break;
948                 }
949 
950                 /* keep searching until we find a perfect match leaf or NULL */
951         } while (IS_TNODE(n));
952 
953         *tp = pn;
954 
955         return n;
956 }
957 
958 /* Return the first fib alias matching TOS with
959  * priority less than or equal to PRIO.
960  */
961 static struct fib_alias *fib_find_alias(struct hlist_head *fah, u8 slen,
962                                         u8 tos, u32 prio, u32 tb_id)
963 {
964         struct fib_alias *fa;
965 
966         if (!fah)
967                 return NULL;
968 
969         hlist_for_each_entry(fa, fah, fa_list) {
970                 if (fa->fa_slen < slen)
971                         continue;
972                 if (fa->fa_slen != slen)
973                         break;
974                 if (fa->tb_id > tb_id)
975                         continue;
976                 if (fa->tb_id != tb_id)
977                         break;
978                 if (fa->fa_tos > tos)
979                         continue;
980                 if (fa->fa_info->fib_priority >= prio || fa->fa_tos < tos)
981                         return fa;
982         }
983 
984         return NULL;
985 }
986 
987 static void trie_rebalance(struct trie *t, struct key_vector *tn)
988 {
989         while (!IS_TRIE(tn))
990                 tn = resize(t, tn);
991 }
992 
993 static int fib_insert_node(struct trie *t, struct key_vector *tp,
994                            struct fib_alias *new, t_key key)
995 {
996         struct key_vector *n, *l;
997 
998         l = leaf_new(key, new);
999         if (!l)
1000                 goto noleaf;
1001 
1002         /* retrieve child from parent node */
1003         n = get_child(tp, get_index(key, tp));
1004 
1005         /* Case 2: n is a LEAF or a TNODE and the key doesn't match.
1006          *
1007          *  Add a new tnode here
1008          *  first tnode need some special handling
1009          *  leaves us in position for handling as case 3
1010          */
1011         if (n) {
1012                 struct key_vector *tn;
1013 
1014                 tn = tnode_new(key, __fls(key ^ n->key), 1);
1015                 if (!tn)
1016                         goto notnode;
1017 
1018                 /* initialize routes out of node */
1019                 NODE_INIT_PARENT(tn, tp);
1020                 put_child(tn, get_index(key, tn) ^ 1, n);
1021 
1022                 /* start adding routes into the node */
1023                 put_child_root(tp, key, tn);
1024                 node_set_parent(n, tn);
1025 
1026                 /* parent now has a NULL spot where the leaf can go */
1027                 tp = tn;
1028         }
1029 
1030         /* Case 3: n is NULL, and will just insert a new leaf */
1031         NODE_INIT_PARENT(l, tp);
1032         put_child_root(tp, key, l);
1033         trie_rebalance(t, tp);
1034 
1035         return 0;
1036 notnode:
1037         node_free(l);
1038 noleaf:
1039         return -ENOMEM;
1040 }
1041 
1042 static int fib_insert_alias(struct trie *t, struct key_vector *tp,
1043                             struct key_vector *l, struct fib_alias *new,
1044                             struct fib_alias *fa, t_key key)
1045 {
1046         if (!l)
1047                 return fib_insert_node(t, tp, new, key);
1048 
1049         if (fa) {
1050                 hlist_add_before_rcu(&new->fa_list, &fa->fa_list);
1051         } else {
1052                 struct fib_alias *last;
1053 
1054                 hlist_for_each_entry(last, &l->leaf, fa_list) {
1055                         if (new->fa_slen < last->fa_slen)
1056                                 break;
1057                         if ((new->fa_slen == last->fa_slen) &&
1058                             (new->tb_id > last->tb_id))
1059                                 break;
1060                         fa = last;
1061                 }
1062 
1063                 if (fa)
1064                         hlist_add_behind_rcu(&new->fa_list, &fa->fa_list);
1065                 else
1066                         hlist_add_head_rcu(&new->fa_list, &l->leaf);
1067         }
1068 
1069         /* if we added to the tail node then we need to update slen */
1070         if (l->slen < new->fa_slen) {
1071                 l->slen = new->fa_slen;
1072                 leaf_push_suffix(tp, l);
1073         }
1074 
1075         return 0;
1076 }
1077 
1078 /* Caller must hold RTNL. */
1079 int fib_table_insert(struct fib_table *tb, struct fib_config *cfg)
1080 {
1081         struct trie *t = (struct trie *)tb->tb_data;
1082         struct fib_alias *fa, *new_fa;
1083         struct key_vector *l, *tp;
1084         unsigned int nlflags = 0;
1085         struct fib_info *fi;
1086         u8 plen = cfg->fc_dst_len;
1087         u8 slen = KEYLENGTH - plen;
1088         u8 tos = cfg->fc_tos;
1089         u32 key;
1090         int err;
1091 
1092         if (plen > KEYLENGTH)
1093                 return -EINVAL;
1094 
1095         key = ntohl(cfg->fc_dst);
1096 
1097         pr_debug("Insert table=%u %08x/%d\n", tb->tb_id, key, plen);
1098 
1099         if ((plen < KEYLENGTH) && (key << plen))
1100                 return -EINVAL;
1101 
1102         fi = fib_create_info(cfg);
1103         if (IS_ERR(fi)) {
1104                 err = PTR_ERR(fi);
1105                 goto err;
1106         }
1107 
1108         l = fib_find_node(t, &tp, key);
1109         fa = l ? fib_find_alias(&l->leaf, slen, tos, fi->fib_priority,
1110                                 tb->tb_id) : NULL;
1111 
1112         /* Now fa, if non-NULL, points to the first fib alias
1113          * with the same keys [prefix,tos,priority], if such key already
1114          * exists or to the node before which we will insert new one.
1115          *
1116          * If fa is NULL, we will need to allocate a new one and
1117          * insert to the tail of the section matching the suffix length
1118          * of the new alias.
1119          */
1120 
1121         if (fa && fa->fa_tos == tos &&
1122             fa->fa_info->fib_priority == fi->fib_priority) {
1123                 struct fib_alias *fa_first, *fa_match;
1124 
1125                 err = -EEXIST;
1126                 if (cfg->fc_nlflags & NLM_F_EXCL)
1127                         goto out;
1128 
1129                 /* We have 2 goals:
1130                  * 1. Find exact match for type, scope, fib_info to avoid
1131                  * duplicate routes
1132                  * 2. Find next 'fa' (or head), NLM_F_APPEND inserts before it
1133                  */
1134                 fa_match = NULL;
1135                 fa_first = fa;
1136                 hlist_for_each_entry_from(fa, fa_list) {
1137                         if ((fa->fa_slen != slen) ||
1138                             (fa->tb_id != tb->tb_id) ||
1139                             (fa->fa_tos != tos))
1140                                 break;
1141                         if (fa->fa_info->fib_priority != fi->fib_priority)
1142                                 break;
1143                         if (fa->fa_type == cfg->fc_type &&
1144                             fa->fa_info == fi) {
1145                                 fa_match = fa;
1146                                 break;
1147                         }
1148                 }
1149 
1150                 if (cfg->fc_nlflags & NLM_F_REPLACE) {
1151                         struct fib_info *fi_drop;
1152                         u8 state;
1153 
1154                         fa = fa_first;
1155                         if (fa_match) {
1156                                 if (fa == fa_match)
1157                                         err = 0;
1158                                 goto out;
1159                         }
1160                         err = -ENOBUFS;
1161                         new_fa = kmem_cache_alloc(fn_alias_kmem, GFP_KERNEL);
1162                         if (!new_fa)
1163                                 goto out;
1164 
1165                         fi_drop = fa->fa_info;
1166                         new_fa->fa_tos = fa->fa_tos;
1167                         new_fa->fa_info = fi;
1168                         new_fa->fa_type = cfg->fc_type;
1169                         state = fa->fa_state;
1170                         new_fa->fa_state = state & ~FA_S_ACCESSED;
1171                         new_fa->fa_slen = fa->fa_slen;
1172                         new_fa->tb_id = tb->tb_id;
1173                         new_fa->fa_default = -1;
1174 
1175                         err = switchdev_fib_ipv4_add(key, plen, fi,
1176                                                      new_fa->fa_tos,
1177                                                      cfg->fc_type,
1178                                                      cfg->fc_nlflags,
1179                                                      tb->tb_id);
1180                         if (err) {
1181                                 switchdev_fib_ipv4_abort(fi);
1182                                 kmem_cache_free(fn_alias_kmem, new_fa);
1183                                 goto out;
1184                         }
1185 
1186                         hlist_replace_rcu(&fa->fa_list, &new_fa->fa_list);
1187 
1188                         alias_free_mem_rcu(fa);
1189 
1190                         fib_release_info(fi_drop);
1191                         if (state & FA_S_ACCESSED)
1192                                 rt_cache_flush(cfg->fc_nlinfo.nl_net);
1193                         rtmsg_fib(RTM_NEWROUTE, htonl(key), new_fa, plen,
1194                                 tb->tb_id, &cfg->fc_nlinfo, NLM_F_REPLACE);
1195 
1196                         goto succeeded;
1197                 }
1198                 /* Error if we find a perfect match which
1199                  * uses the same scope, type, and nexthop
1200                  * information.
1201                  */
1202                 if (fa_match)
1203                         goto out;
1204 
1205                 if (cfg->fc_nlflags & NLM_F_APPEND)
1206                         nlflags = NLM_F_APPEND;
1207                 else
1208                         fa = fa_first;
1209         }
1210         err = -ENOENT;
1211         if (!(cfg->fc_nlflags & NLM_F_CREATE))
1212                 goto out;
1213 
1214         err = -ENOBUFS;
1215         new_fa = kmem_cache_alloc(fn_alias_kmem, GFP_KERNEL);
1216         if (!new_fa)
1217                 goto out;
1218 
1219         new_fa->fa_info = fi;
1220         new_fa->fa_tos = tos;
1221         new_fa->fa_type = cfg->fc_type;
1222         new_fa->fa_state = 0;
1223         new_fa->fa_slen = slen;
1224         new_fa->tb_id = tb->tb_id;
1225         new_fa->fa_default = -1;
1226 
1227         /* (Optionally) offload fib entry to switch hardware. */
1228         err = switchdev_fib_ipv4_add(key, plen, fi, tos, cfg->fc_type,
1229                                      cfg->fc_nlflags, tb->tb_id);
1230         if (err) {
1231                 switchdev_fib_ipv4_abort(fi);
1232                 goto out_free_new_fa;
1233         }
1234 
1235         /* Insert new entry to the list. */
1236         err = fib_insert_alias(t, tp, l, new_fa, fa, key);
1237         if (err)
1238                 goto out_sw_fib_del;
1239 
1240         if (!plen)
1241                 tb->tb_num_default++;
1242 
1243         rt_cache_flush(cfg->fc_nlinfo.nl_net);
1244         rtmsg_fib(RTM_NEWROUTE, htonl(key), new_fa, plen, new_fa->tb_id,
1245                   &cfg->fc_nlinfo, nlflags);
1246 succeeded:
1247         return 0;
1248 
1249 out_sw_fib_del:
1250         switchdev_fib_ipv4_del(key, plen, fi, tos, cfg->fc_type, tb->tb_id);
1251 out_free_new_fa:
1252         kmem_cache_free(fn_alias_kmem, new_fa);
1253 out:
1254         fib_release_info(fi);
1255 err:
1256         return err;
1257 }
1258 
1259 static inline t_key prefix_mismatch(t_key key, struct key_vector *n)
1260 {
1261         t_key prefix = n->key;
1262 
1263         return (key ^ prefix) & (prefix | -prefix);
1264 }
1265 
1266 /* should be called with rcu_read_lock */
1267 int fib_table_lookup(struct fib_table *tb, const struct flowi4 *flp,
1268                      struct fib_result *res, int fib_flags)
1269 {
1270         struct trie *t = (struct trie *) tb->tb_data;
1271 #ifdef CONFIG_IP_FIB_TRIE_STATS
1272         struct trie_use_stats __percpu *stats = t->stats;
1273 #endif
1274         const t_key key = ntohl(flp->daddr);
1275         struct key_vector *n, *pn;
1276         struct fib_alias *fa;
1277         unsigned long index;
1278         t_key cindex;
1279 
1280         trace_fib_table_lookup(tb->tb_id, flp);
1281 
1282         pn = t->kv;
1283         cindex = 0;
1284 
1285         n = get_child_rcu(pn, cindex);
1286         if (!n)
1287                 return -EAGAIN;
1288 
1289 #ifdef CONFIG_IP_FIB_TRIE_STATS
1290         this_cpu_inc(stats->gets);
1291 #endif
1292 
1293         /* Step 1: Travel to the longest prefix match in the trie */
1294         for (;;) {
1295                 index = get_cindex(key, n);
1296 
1297                 /* This bit of code is a bit tricky but it combines multiple
1298                  * checks into a single check.  The prefix consists of the
1299                  * prefix plus zeros for the "bits" in the prefix. The index
1300                  * is the difference between the key and this value.  From
1301                  * this we can actually derive several pieces of data.
1302                  *   if (index >= (1ul << bits))
1303                  *     we have a mismatch in skip bits and failed
1304                  *   else
1305                  *     we know the value is cindex
1306                  *
1307                  * This check is safe even if bits == KEYLENGTH due to the
1308                  * fact that we can only allocate a node with 32 bits if a
1309                  * long is greater than 32 bits.
1310                  */
1311                 if (index >= (1ul << n->bits))
1312                         break;
1313 
1314                 /* we have found a leaf. Prefixes have already been compared */
1315                 if (IS_LEAF(n))
1316                         goto found;
1317 
1318                 /* only record pn and cindex if we are going to be chopping
1319                  * bits later.  Otherwise we are just wasting cycles.
1320                  */
1321                 if (n->slen > n->pos) {
1322                         pn = n;
1323                         cindex = index;
1324                 }
1325 
1326                 n = get_child_rcu(n, index);
1327                 if (unlikely(!n))
1328                         goto backtrace;
1329         }
1330 
1331         /* Step 2: Sort out leaves and begin backtracing for longest prefix */
1332         for (;;) {
1333                 /* record the pointer where our next node pointer is stored */
1334                 struct key_vector __rcu **cptr = n->tnode;
1335 
1336                 /* This test verifies that none of the bits that differ
1337                  * between the key and the prefix exist in the region of
1338                  * the lsb and higher in the prefix.
1339                  */
1340                 if (unlikely(prefix_mismatch(key, n)) || (n->slen == n->pos))
1341                         goto backtrace;
1342 
1343                 /* exit out and process leaf */
1344                 if (unlikely(IS_LEAF(n)))
1345                         break;
1346 
1347                 /* Don't bother recording parent info.  Since we are in
1348                  * prefix match mode we will have to come back to wherever
1349                  * we started this traversal anyway
1350                  */
1351 
1352                 while ((n = rcu_dereference(*cptr)) == NULL) {
1353 backtrace:
1354 #ifdef CONFIG_IP_FIB_TRIE_STATS
1355                         if (!n)
1356                                 this_cpu_inc(stats->null_node_hit);
1357 #endif
1358                         /* If we are at cindex 0 there are no more bits for
1359                          * us to strip at this level so we must ascend back
1360                          * up one level to see if there are any more bits to
1361                          * be stripped there.
1362                          */
1363                         while (!cindex) {
1364                                 t_key pkey = pn->key;
1365 
1366                                 /* If we don't have a parent then there is
1367                                  * nothing for us to do as we do not have any
1368                                  * further nodes to parse.
1369                                  */
1370                                 if (IS_TRIE(pn))
1371                                         return -EAGAIN;
1372 #ifdef CONFIG_IP_FIB_TRIE_STATS
1373                                 this_cpu_inc(stats->backtrack);
1374 #endif
1375                                 /* Get Child's index */
1376                                 pn = node_parent_rcu(pn);
1377                                 cindex = get_index(pkey, pn);
1378                         }
1379 
1380                         /* strip the least significant bit from the cindex */
1381                         cindex &= cindex - 1;
1382 
1383                         /* grab pointer for next child node */
1384                         cptr = &pn->tnode[cindex];
1385                 }
1386         }
1387 
1388 found:
1389         /* this line carries forward the xor from earlier in the function */
1390         index = key ^ n->key;
1391 
1392         /* Step 3: Process the leaf, if that fails fall back to backtracing */
1393         hlist_for_each_entry_rcu(fa, &n->leaf, fa_list) {
1394                 struct fib_info *fi = fa->fa_info;
1395                 int nhsel, err;
1396 
1397                 if ((BITS_PER_LONG > KEYLENGTH) || (fa->fa_slen < KEYLENGTH)) {
1398                         if (index >= (1ul << fa->fa_slen))
1399                                 continue;
1400                 }
1401                 if (fa->fa_tos && fa->fa_tos != flp->flowi4_tos)
1402                         continue;
1403                 if (fi->fib_dead)
1404                         continue;
1405                 if (fa->fa_info->fib_scope < flp->flowi4_scope)
1406                         continue;
1407                 fib_alias_accessed(fa);
1408                 err = fib_props[fa->fa_type].error;
1409                 if (unlikely(err < 0)) {
1410 #ifdef CONFIG_IP_FIB_TRIE_STATS
1411                         this_cpu_inc(stats->semantic_match_passed);
1412 #endif
1413                         return err;
1414                 }
1415                 if (fi->fib_flags & RTNH_F_DEAD)
1416                         continue;
1417                 for (nhsel = 0; nhsel < fi->fib_nhs; nhsel++) {
1418                         const struct fib_nh *nh = &fi->fib_nh[nhsel];
1419                         struct in_device *in_dev = __in_dev_get_rcu(nh->nh_dev);
1420 
1421                         if (nh->nh_flags & RTNH_F_DEAD)
1422                                 continue;
1423                         if (in_dev &&
1424                             IN_DEV_IGNORE_ROUTES_WITH_LINKDOWN(in_dev) &&
1425                             nh->nh_flags & RTNH_F_LINKDOWN &&
1426                             !(fib_flags & FIB_LOOKUP_IGNORE_LINKSTATE))
1427                                 continue;
1428                         if (!(flp->flowi4_flags & FLOWI_FLAG_SKIP_NH_OIF)) {
1429                                 if (flp->flowi4_oif &&
1430                                     flp->flowi4_oif != nh->nh_oif)
1431                                         continue;
1432                         }
1433 
1434                         if (!(fib_flags & FIB_LOOKUP_NOREF))
1435                                 atomic_inc(&fi->fib_clntref);
1436 
1437                         res->prefixlen = KEYLENGTH - fa->fa_slen;
1438                         res->nh_sel = nhsel;
1439                         res->type = fa->fa_type;
1440                         res->scope = fi->fib_scope;
1441                         res->fi = fi;
1442                         res->table = tb;
1443                         res->fa_head = &n->leaf;
1444 #ifdef CONFIG_IP_FIB_TRIE_STATS
1445                         this_cpu_inc(stats->semantic_match_passed);
1446 #endif
1447                         trace_fib_table_lookup_nh(nh);
1448 
1449                         return err;
1450                 }
1451         }
1452 #ifdef CONFIG_IP_FIB_TRIE_STATS
1453         this_cpu_inc(stats->semantic_match_miss);
1454 #endif
1455         goto backtrace;
1456 }
1457 EXPORT_SYMBOL_GPL(fib_table_lookup);
1458 
1459 static void fib_remove_alias(struct trie *t, struct key_vector *tp,
1460                              struct key_vector *l, struct fib_alias *old)
1461 {
1462         /* record the location of the previous list_info entry */
1463         struct hlist_node **pprev = old->fa_list.pprev;
1464         struct fib_alias *fa = hlist_entry(pprev, typeof(*fa), fa_list.next);
1465 
1466         /* remove the fib_alias from the list */
1467         hlist_del_rcu(&old->fa_list);
1468 
1469         /* if we emptied the list this leaf will be freed and we can sort
1470          * out parent suffix lengths as a part of trie_rebalance
1471          */
1472         if (hlist_empty(&l->leaf)) {
1473                 put_child_root(tp, l->key, NULL);
1474                 node_free(l);
1475                 trie_rebalance(t, tp);
1476                 return;
1477         }
1478 
1479         /* only access fa if it is pointing at the last valid hlist_node */
1480         if (*pprev)
1481                 return;
1482 
1483         /* update the trie with the latest suffix length */
1484         l->slen = fa->fa_slen;
1485         leaf_pull_suffix(tp, l);
1486 }
1487 
1488 /* Caller must hold RTNL. */
1489 int fib_table_delete(struct fib_table *tb, struct fib_config *cfg)
1490 {
1491         struct trie *t = (struct trie *) tb->tb_data;
1492         struct fib_alias *fa, *fa_to_delete;
1493         struct key_vector *l, *tp;
1494         u8 plen = cfg->fc_dst_len;
1495         u8 slen = KEYLENGTH - plen;
1496         u8 tos = cfg->fc_tos;
1497         u32 key;
1498 
1499         if (plen > KEYLENGTH)
1500                 return -EINVAL;
1501 
1502         key = ntohl(cfg->fc_dst);
1503 
1504         if ((plen < KEYLENGTH) && (key << plen))
1505                 return -EINVAL;
1506 
1507         l = fib_find_node(t, &tp, key);
1508         if (!l)
1509                 return -ESRCH;
1510 
1511         fa = fib_find_alias(&l->leaf, slen, tos, 0, tb->tb_id);
1512         if (!fa)
1513                 return -ESRCH;
1514 
1515         pr_debug("Deleting %08x/%d tos=%d t=%p\n", key, plen, tos, t);
1516 
1517         fa_to_delete = NULL;
1518         hlist_for_each_entry_from(fa, fa_list) {
1519                 struct fib_info *fi = fa->fa_info;
1520 
1521                 if ((fa->fa_slen != slen) ||
1522                     (fa->tb_id != tb->tb_id) ||
1523                     (fa->fa_tos != tos))
1524                         break;
1525 
1526                 if ((!cfg->fc_type || fa->fa_type == cfg->fc_type) &&
1527                     (cfg->fc_scope == RT_SCOPE_NOWHERE ||
1528                      fa->fa_info->fib_scope == cfg->fc_scope) &&
1529                     (!cfg->fc_prefsrc ||
1530                      fi->fib_prefsrc == cfg->fc_prefsrc) &&
1531                     (!cfg->fc_protocol ||
1532                      fi->fib_protocol == cfg->fc_protocol) &&
1533                     fib_nh_match(cfg, fi) == 0) {
1534                         fa_to_delete = fa;
1535                         break;
1536                 }
1537         }
1538 
1539         if (!fa_to_delete)
1540                 return -ESRCH;
1541 
1542         switchdev_fib_ipv4_del(key, plen, fa_to_delete->fa_info, tos,
1543                                cfg->fc_type, tb->tb_id);
1544 
1545         rtmsg_fib(RTM_DELROUTE, htonl(key), fa_to_delete, plen, tb->tb_id,
1546                   &cfg->fc_nlinfo, 0);
1547 
1548         if (!plen)
1549                 tb->tb_num_default--;
1550 
1551         fib_remove_alias(t, tp, l, fa_to_delete);
1552 
1553         if (fa_to_delete->fa_state & FA_S_ACCESSED)
1554                 rt_cache_flush(cfg->fc_nlinfo.nl_net);
1555 
1556         fib_release_info(fa_to_delete->fa_info);
1557         alias_free_mem_rcu(fa_to_delete);
1558         return 0;
1559 }
1560 
1561 /* Scan for the next leaf starting at the provided key value */
1562 static struct key_vector *leaf_walk_rcu(struct key_vector **tn, t_key key)
1563 {
1564         struct key_vector *pn, *n = *tn;
1565         unsigned long cindex;
1566 
1567         /* this loop is meant to try and find the key in the trie */
1568         do {
1569                 /* record parent and next child index */
1570                 pn = n;
1571                 cindex = (key > pn->key) ? get_index(key, pn) : 0;
1572 
1573                 if (cindex >> pn->bits)
1574                         break;
1575 
1576                 /* descend into the next child */
1577                 n = get_child_rcu(pn, cindex++);
1578                 if (!n)
1579                         break;
1580 
1581                 /* guarantee forward progress on the keys */
1582                 if (IS_LEAF(n) && (n->key >= key))
1583                         goto found;
1584         } while (IS_TNODE(n));
1585 
1586         /* this loop will search for the next leaf with a greater key */
1587         while (!IS_TRIE(pn)) {
1588                 /* if we exhausted the parent node we will need to climb */
1589                 if (cindex >= (1ul << pn->bits)) {
1590                         t_key pkey = pn->key;
1591 
1592                         pn = node_parent_rcu(pn);
1593                         cindex = get_index(pkey, pn) + 1;
1594                         continue;
1595                 }
1596 
1597                 /* grab the next available node */
1598                 n = get_child_rcu(pn, cindex++);
1599                 if (!n)
1600                         continue;
1601 
1602                 /* no need to compare keys since we bumped the index */
1603                 if (IS_LEAF(n))
1604                         goto found;
1605 
1606                 /* Rescan start scanning in new node */
1607                 pn = n;
1608                 cindex = 0;
1609         }
1610 
1611         *tn = pn;
1612         return NULL; /* Root of trie */
1613 found:
1614         /* if we are at the limit for keys just return NULL for the tnode */
1615         *tn = pn;
1616         return n;
1617 }
1618 
1619 static void fib_trie_free(struct fib_table *tb)
1620 {
1621         struct trie *t = (struct trie *)tb->tb_data;
1622         struct key_vector *pn = t->kv;
1623         unsigned long cindex = 1;
1624         struct hlist_node *tmp;
1625         struct fib_alias *fa;
1626 
1627         /* walk trie in reverse order and free everything */
1628         for (;;) {
1629                 struct key_vector *n;
1630 
1631                 if (!(cindex--)) {
1632                         t_key pkey = pn->key;
1633 
1634                         if (IS_TRIE(pn))
1635                                 break;
1636 
1637                         n = pn;
1638                         pn = node_parent(pn);
1639 
1640                         /* drop emptied tnode */
1641                         put_child_root(pn, n->key, NULL);
1642                         node_free(n);
1643 
1644                         cindex = get_index(pkey, pn);
1645 
1646                         continue;
1647                 }
1648 
1649                 /* grab the next available node */
1650                 n = get_child(pn, cindex);
1651                 if (!n)
1652                         continue;
1653 
1654                 if (IS_TNODE(n)) {
1655                         /* record pn and cindex for leaf walking */
1656                         pn = n;
1657                         cindex = 1ul << n->bits;
1658 
1659                         continue;
1660                 }
1661 
1662                 hlist_for_each_entry_safe(fa, tmp, &n->leaf, fa_list) {
1663                         hlist_del_rcu(&fa->fa_list);
1664                         alias_free_mem_rcu(fa);
1665                 }
1666 
1667                 put_child_root(pn, n->key, NULL);
1668                 node_free(n);
1669         }
1670 
1671 #ifdef CONFIG_IP_FIB_TRIE_STATS
1672         free_percpu(t->stats);
1673 #endif
1674         kfree(tb);
1675 }
1676 
1677 struct fib_table *fib_trie_unmerge(struct fib_table *oldtb)
1678 {
1679         struct trie *ot = (struct trie *)oldtb->tb_data;
1680         struct key_vector *l, *tp = ot->kv;
1681         struct fib_table *local_tb;
1682         struct fib_alias *fa;
1683         struct trie *lt;
1684         t_key key = 0;
1685 
1686         if (oldtb->tb_data == oldtb->__data)
1687                 return oldtb;
1688 
1689         local_tb = fib_trie_table(RT_TABLE_LOCAL, NULL);
1690         if (!local_tb)
1691                 return NULL;
1692 
1693         lt = (struct trie *)local_tb->tb_data;
1694 
1695         while ((l = leaf_walk_rcu(&tp, key)) != NULL) {
1696                 struct key_vector *local_l = NULL, *local_tp;
1697 
1698                 hlist_for_each_entry_rcu(fa, &l->leaf, fa_list) {
1699                         struct fib_alias *new_fa;
1700 
1701                         if (local_tb->tb_id != fa->tb_id)
1702                                 continue;
1703 
1704                         /* clone fa for new local table */
1705                         new_fa = kmem_cache_alloc(fn_alias_kmem, GFP_KERNEL);
1706                         if (!new_fa)
1707                                 goto out;
1708 
1709                         memcpy(new_fa, fa, sizeof(*fa));
1710 
1711                         /* insert clone into table */
1712                         if (!local_l)
1713                                 local_l = fib_find_node(lt, &local_tp, l->key);
1714 
1715                         if (fib_insert_alias(lt, local_tp, local_l, new_fa,
1716                                              NULL, l->key))
1717                                 goto out;
1718                 }
1719 
1720                 /* stop loop if key wrapped back to 0 */
1721                 key = l->key + 1;
1722                 if (key < l->key)
1723                         break;
1724         }
1725 
1726         return local_tb;
1727 out:
1728         fib_trie_free(local_tb);
1729 
1730         return NULL;
1731 }
1732 
1733 /* Caller must hold RTNL */
1734 void fib_table_flush_external(struct fib_table *tb)
1735 {
1736         struct trie *t = (struct trie *)tb->tb_data;
1737         struct key_vector *pn = t->kv;
1738         unsigned long cindex = 1;
1739         struct hlist_node *tmp;
1740         struct fib_alias *fa;
1741 
1742         /* walk trie in reverse order */
1743         for (;;) {
1744                 unsigned char slen = 0;
1745                 struct key_vector *n;
1746 
1747                 if (!(cindex--)) {
1748                         t_key pkey = pn->key;
1749 
1750                         /* cannot resize the trie vector */
1751                         if (IS_TRIE(pn))
1752                                 break;
1753 
1754                         /* resize completed node */
1755                         pn = resize(t, pn);
1756                         cindex = get_index(pkey, pn);
1757 
1758                         continue;
1759                 }
1760 
1761                 /* grab the next available node */
1762                 n = get_child(pn, cindex);
1763                 if (!n)
1764                         continue;
1765 
1766                 if (IS_TNODE(n)) {
1767                         /* record pn and cindex for leaf walking */
1768                         pn = n;
1769                         cindex = 1ul << n->bits;
1770 
1771                         continue;
1772                 }
1773 
1774                 hlist_for_each_entry_safe(fa, tmp, &n->leaf, fa_list) {
1775                         struct fib_info *fi = fa->fa_info;
1776 
1777                         /* if alias was cloned to local then we just
1778                          * need to remove the local copy from main
1779                          */
1780                         if (tb->tb_id != fa->tb_id) {
1781                                 hlist_del_rcu(&fa->fa_list);
1782                                 alias_free_mem_rcu(fa);
1783                                 continue;
1784                         }
1785 
1786                         /* record local slen */
1787                         slen = fa->fa_slen;
1788 
1789                         if (!fi || !(fi->fib_flags & RTNH_F_OFFLOAD))
1790                                 continue;
1791 
1792                         switchdev_fib_ipv4_del(n->key, KEYLENGTH - fa->fa_slen,
1793                                                fi, fa->fa_tos, fa->fa_type,
1794                                                tb->tb_id);
1795                 }
1796 
1797                 /* update leaf slen */
1798                 n->slen = slen;
1799 
1800                 if (hlist_empty(&n->leaf)) {
1801                         put_child_root(pn, n->key, NULL);
1802                         node_free(n);
1803                 }
1804         }
1805 }
1806 
1807 /* Caller must hold RTNL. */
1808 int fib_table_flush(struct fib_table *tb)
1809 {
1810         struct trie *t = (struct trie *)tb->tb_data;
1811         struct key_vector *pn = t->kv;
1812         unsigned long cindex = 1;
1813         struct hlist_node *tmp;
1814         struct fib_alias *fa;
1815         int found = 0;
1816 
1817         /* walk trie in reverse order */
1818         for (;;) {
1819                 unsigned char slen = 0;
1820                 struct key_vector *n;
1821 
1822                 if (!(cindex--)) {
1823                         t_key pkey = pn->key;
1824 
1825                         /* cannot resize the trie vector */
1826                         if (IS_TRIE(pn))
1827                                 break;
1828 
1829                         /* resize completed node */
1830                         pn = resize(t, pn);
1831                         cindex = get_index(pkey, pn);
1832 
1833                         continue;
1834                 }
1835 
1836                 /* grab the next available node */
1837                 n = get_child(pn, cindex);
1838                 if (!n)
1839                         continue;
1840 
1841                 if (IS_TNODE(n)) {
1842                         /* record pn and cindex for leaf walking */
1843                         pn = n;
1844                         cindex = 1ul << n->bits;
1845 
1846                         continue;
1847                 }
1848 
1849                 hlist_for_each_entry_safe(fa, tmp, &n->leaf, fa_list) {
1850                         struct fib_info *fi = fa->fa_info;
1851 
1852                         if (!fi || !(fi->fib_flags & RTNH_F_DEAD)) {
1853                                 slen = fa->fa_slen;
1854                                 continue;
1855                         }
1856 
1857                         switchdev_fib_ipv4_del(n->key, KEYLENGTH - fa->fa_slen,
1858                                                fi, fa->fa_tos, fa->fa_type,
1859                                                tb->tb_id);
1860                         hlist_del_rcu(&fa->fa_list);
1861                         fib_release_info(fa->fa_info);
1862                         alias_free_mem_rcu(fa);
1863                         found++;
1864                 }
1865 
1866                 /* update leaf slen */
1867                 n->slen = slen;
1868 
1869                 if (hlist_empty(&n->leaf)) {
1870                         put_child_root(pn, n->key, NULL);
1871                         node_free(n);
1872                 }
1873         }
1874 
1875         pr_debug("trie_flush found=%d\n", found);
1876         return found;
1877 }
1878 
1879 static void __trie_free_rcu(struct rcu_head *head)
1880 {
1881         struct fib_table *tb = container_of(head, struct fib_table, rcu);
1882 #ifdef CONFIG_IP_FIB_TRIE_STATS
1883         struct trie *t = (struct trie *)tb->tb_data;
1884 
1885         if (tb->tb_data == tb->__data)
1886                 free_percpu(t->stats);
1887 #endif /* CONFIG_IP_FIB_TRIE_STATS */
1888         kfree(tb);
1889 }
1890 
1891 void fib_free_table(struct fib_table *tb)
1892 {
1893         call_rcu(&tb->rcu, __trie_free_rcu);
1894 }
1895 
1896 static int fn_trie_dump_leaf(struct key_vector *l, struct fib_table *tb,
1897                              struct sk_buff *skb, struct netlink_callback *cb)
1898 {
1899         __be32 xkey = htonl(l->key);
1900         struct fib_alias *fa;
1901         int i, s_i;
1902 
1903         s_i = cb->args[4];
1904         i = 0;
1905 
1906         /* rcu_read_lock is hold by caller */
1907         hlist_for_each_entry_rcu(fa, &l->leaf, fa_list) {
1908                 if (i < s_i) {
1909                         i++;
1910                         continue;
1911                 }
1912 
1913                 if (tb->tb_id != fa->tb_id) {
1914                         i++;
1915                         continue;
1916                 }
1917 
1918                 if (fib_dump_info(skb, NETLINK_CB(cb->skb).portid,
1919                                   cb->nlh->nlmsg_seq,
1920                                   RTM_NEWROUTE,
1921                                   tb->tb_id,
1922                                   fa->fa_type,
1923                                   xkey,
1924                                   KEYLENGTH - fa->fa_slen,
1925                                   fa->fa_tos,
1926                                   fa->fa_info, NLM_F_MULTI) < 0) {
1927                         cb->args[4] = i;
1928                         return -1;
1929                 }
1930                 i++;
1931         }
1932 
1933         cb->args[4] = i;
1934         return skb->len;
1935 }
1936 
1937 /* rcu_read_lock needs to be hold by caller from readside */
1938 int fib_table_dump(struct fib_table *tb, struct sk_buff *skb,
1939                    struct netlink_callback *cb)
1940 {
1941         struct trie *t = (struct trie *)tb->tb_data;
1942         struct key_vector *l, *tp = t->kv;
1943         /* Dump starting at last key.
1944          * Note: 0.0.0.0/0 (ie default) is first key.
1945          */
1946         int count = cb->args[2];
1947         t_key key = cb->args[3];
1948 
1949         while ((l = leaf_walk_rcu(&tp, key)) != NULL) {
1950                 if (fn_trie_dump_leaf(l, tb, skb, cb) < 0) {
1951                         cb->args[3] = key;
1952                         cb->args[2] = count;
1953                         return -1;
1954                 }
1955 
1956                 ++count;
1957                 key = l->key + 1;
1958 
1959                 memset(&cb->args[4], 0,
1960                        sizeof(cb->args) - 4*sizeof(cb->args[0]));
1961 
1962                 /* stop loop if key wrapped back to 0 */
1963                 if (key < l->key)
1964                         break;
1965         }
1966 
1967         cb->args[3] = key;
1968         cb->args[2] = count;
1969 
1970         return skb->len;
1971 }
1972 
1973 void __init fib_trie_init(void)
1974 {
1975         fn_alias_kmem = kmem_cache_create("ip_fib_alias",
1976                                           sizeof(struct fib_alias),
1977                                           0, SLAB_PANIC, NULL);
1978 
1979         trie_leaf_kmem = kmem_cache_create("ip_fib_trie",
1980                                            LEAF_SIZE,
1981                                            0, SLAB_PANIC, NULL);
1982 }
1983 
1984 struct fib_table *fib_trie_table(u32 id, struct fib_table *alias)
1985 {
1986         struct fib_table *tb;
1987         struct trie *t;
1988         size_t sz = sizeof(*tb);
1989 
1990         if (!alias)
1991                 sz += sizeof(struct trie);
1992 
1993         tb = kzalloc(sz, GFP_KERNEL);
1994         if (!tb)
1995                 return NULL;
1996 
1997         tb->tb_id = id;
1998         tb->tb_num_default = 0;
1999         tb->tb_data = (alias ? alias->__data : tb->__data);
2000 
2001         if (alias)
2002                 return tb;
2003 
2004         t = (struct trie *) tb->tb_data;
2005         t->kv[0].pos = KEYLENGTH;
2006         t->kv[0].slen = KEYLENGTH;
2007 #ifdef CONFIG_IP_FIB_TRIE_STATS
2008         t->stats = alloc_percpu(struct trie_use_stats);
2009         if (!t->stats) {
2010                 kfree(tb);
2011                 tb = NULL;
2012         }
2013 #endif
2014 
2015         return tb;
2016 }
2017 
2018 #ifdef CONFIG_PROC_FS
2019 /* Depth first Trie walk iterator */
2020 struct fib_trie_iter {
2021         struct seq_net_private p;
2022         struct fib_table *tb;
2023         struct key_vector *tnode;
2024         unsigned int index;
2025         unsigned int depth;
2026 };
2027 
2028 static struct key_vector *fib_trie_get_next(struct fib_trie_iter *iter)
2029 {
2030         unsigned long cindex = iter->index;
2031         struct key_vector *pn = iter->tnode;
2032         t_key pkey;
2033 
2034         pr_debug("get_next iter={node=%p index=%d depth=%d}\n",
2035                  iter->tnode, iter->index, iter->depth);
2036 
2037         while (!IS_TRIE(pn)) {
2038                 while (cindex < child_length(pn)) {
2039                         struct key_vector *n = get_child_rcu(pn, cindex++);
2040 
2041                         if (!n)
2042                                 continue;
2043 
2044                         if (IS_LEAF(n)) {
2045                                 iter->tnode = pn;
2046                                 iter->index = cindex;
2047                         } else {
2048                                 /* push down one level */
2049                                 iter->tnode = n;
2050                                 iter->index = 0;
2051                                 ++iter->depth;
2052                         }
2053 
2054                         return n;
2055                 }
2056 
2057                 /* Current node exhausted, pop back up */
2058                 pkey = pn->key;
2059                 pn = node_parent_rcu(pn);
2060                 cindex = get_index(pkey, pn) + 1;
2061                 --iter->depth;
2062         }
2063 
2064         /* record root node so further searches know we are done */
2065         iter->tnode = pn;
2066         iter->index = 0;
2067 
2068         return NULL;
2069 }
2070 
2071 static struct key_vector *fib_trie_get_first(struct fib_trie_iter *iter,
2072                                              struct trie *t)
2073 {
2074         struct key_vector *n, *pn;
2075 
2076         if (!t)
2077                 return NULL;
2078 
2079         pn = t->kv;
2080         n = rcu_dereference(pn->tnode[0]);
2081         if (!n)
2082                 return NULL;
2083 
2084         if (IS_TNODE(n)) {
2085                 iter->tnode = n;
2086                 iter->index = 0;
2087                 iter->depth = 1;
2088         } else {
2089                 iter->tnode = pn;
2090                 iter->index = 0;
2091                 iter->depth = 0;
2092         }
2093 
2094         return n;
2095 }
2096 
2097 static void trie_collect_stats(struct trie *t, struct trie_stat *s)
2098 {
2099         struct key_vector *n;
2100         struct fib_trie_iter iter;
2101 
2102         memset(s, 0, sizeof(*s));
2103 
2104         rcu_read_lock();
2105         for (n = fib_trie_get_first(&iter, t); n; n = fib_trie_get_next(&iter)) {
2106                 if (IS_LEAF(n)) {
2107                         struct fib_alias *fa;
2108 
2109                         s->leaves++;
2110                         s->totdepth += iter.depth;
2111                         if (iter.depth > s->maxdepth)
2112                                 s->maxdepth = iter.depth;
2113 
2114                         hlist_for_each_entry_rcu(fa, &n->leaf, fa_list)
2115                                 ++s->prefixes;
2116                 } else {
2117                         s->tnodes++;
2118                         if (n->bits < MAX_STAT_DEPTH)
2119                                 s->nodesizes[n->bits]++;
2120                         s->nullpointers += tn_info(n)->empty_children;
2121                 }
2122         }
2123         rcu_read_unlock();
2124 }
2125 
2126 /*
2127  *      This outputs /proc/net/fib_triestats
2128  */
2129 static void trie_show_stats(struct seq_file *seq, struct trie_stat *stat)
2130 {
2131         unsigned int i, max, pointers, bytes, avdepth;
2132 
2133         if (stat->leaves)
2134                 avdepth = stat->totdepth*100 / stat->leaves;
2135         else
2136                 avdepth = 0;
2137 
2138         seq_printf(seq, "\tAver depth:     %u.%02d\n",
2139                    avdepth / 100, avdepth % 100);
2140         seq_printf(seq, "\tMax depth:      %u\n", stat->maxdepth);
2141 
2142         seq_printf(seq, "\tLeaves:         %u\n", stat->leaves);
2143         bytes = LEAF_SIZE * stat->leaves;
2144 
2145         seq_printf(seq, "\tPrefixes:       %u\n", stat->prefixes);
2146         bytes += sizeof(struct fib_alias) * stat->prefixes;
2147 
2148         seq_printf(seq, "\tInternal nodes: %u\n\t", stat->tnodes);
2149         bytes += TNODE_SIZE(0) * stat->tnodes;
2150 
2151         max = MAX_STAT_DEPTH;
2152         while (max > 0 && stat->nodesizes[max-1] == 0)
2153                 max--;
2154 
2155         pointers = 0;
2156         for (i = 1; i < max; i++)
2157                 if (stat->nodesizes[i] != 0) {
2158                         seq_printf(seq, "  %u: %u",  i, stat->nodesizes[i]);
2159                         pointers += (1<<i) * stat->nodesizes[i];
2160                 }
2161         seq_putc(seq, '\n');
2162         seq_printf(seq, "\tPointers: %u\n", pointers);
2163 
2164         bytes += sizeof(struct key_vector *) * pointers;
2165         seq_printf(seq, "Null ptrs: %u\n", stat->nullpointers);
2166         seq_printf(seq, "Total size: %u  kB\n", (bytes + 1023) / 1024);
2167 }
2168 
2169 #ifdef CONFIG_IP_FIB_TRIE_STATS
2170 static void trie_show_usage(struct seq_file *seq,
2171                             const struct trie_use_stats __percpu *stats)
2172 {
2173         struct trie_use_stats s = { 0 };
2174         int cpu;
2175 
2176         /* loop through all of the CPUs and gather up the stats */
2177         for_each_possible_cpu(cpu) {
2178                 const struct trie_use_stats *pcpu = per_cpu_ptr(stats, cpu);
2179 
2180                 s.gets += pcpu->gets;
2181                 s.backtrack += pcpu->backtrack;
2182                 s.semantic_match_passed += pcpu->semantic_match_passed;
2183                 s.semantic_match_miss += pcpu->semantic_match_miss;
2184                 s.null_node_hit += pcpu->null_node_hit;
2185                 s.resize_node_skipped += pcpu->resize_node_skipped;
2186         }
2187 
2188         seq_printf(seq, "\nCounters:\n---------\n");
2189         seq_printf(seq, "gets = %u\n", s.gets);
2190         seq_printf(seq, "backtracks = %u\n", s.backtrack);
2191         seq_printf(seq, "semantic match passed = %u\n",
2192                    s.semantic_match_passed);
2193         seq_printf(seq, "semantic match miss = %u\n", s.semantic_match_miss);
2194         seq_printf(seq, "null node hit= %u\n", s.null_node_hit);
2195         seq_printf(seq, "skipped node resize = %u\n\n", s.resize_node_skipped);
2196 }
2197 #endif /*  CONFIG_IP_FIB_TRIE_STATS */
2198 
2199 static void fib_table_print(struct seq_file *seq, struct fib_table *tb)
2200 {
2201         if (tb->tb_id == RT_TABLE_LOCAL)
2202                 seq_puts(seq, "Local:\n");
2203         else if (tb->tb_id == RT_TABLE_MAIN)
2204                 seq_puts(seq, "Main:\n");
2205         else
2206                 seq_printf(seq, "Id %d:\n", tb->tb_id);
2207 }
2208 
2209 
2210 static int fib_triestat_seq_show(struct seq_file *seq, void *v)
2211 {
2212         struct net *net = (struct net *)seq->private;
2213         unsigned int h;
2214 
2215         seq_printf(seq,
2216                    "Basic info: size of leaf:"
2217                    " %Zd bytes, size of tnode: %Zd bytes.\n",
2218                    LEAF_SIZE, TNODE_SIZE(0));
2219 
2220         for (h = 0; h < FIB_TABLE_HASHSZ; h++) {
2221                 struct hlist_head *head = &net->ipv4.fib_table_hash[h];
2222                 struct fib_table *tb;
2223 
2224                 hlist_for_each_entry_rcu(tb, head, tb_hlist) {
2225                         struct trie *t = (struct trie *) tb->tb_data;
2226                         struct trie_stat stat;
2227 
2228                         if (!t)
2229                                 continue;
2230 
2231                         fib_table_print(seq, tb);
2232 
2233                         trie_collect_stats(t, &stat);
2234                         trie_show_stats(seq, &stat);
2235 #ifdef CONFIG_IP_FIB_TRIE_STATS
2236                         trie_show_usage(seq, t->stats);
2237 #endif
2238                 }
2239         }
2240 
2241         return 0;
2242 }
2243 
2244 static int fib_triestat_seq_open(struct inode *inode, struct file *file)
2245 {
2246         return single_open_net(inode, file, fib_triestat_seq_show);
2247 }
2248 
2249 static const struct file_operations fib_triestat_fops = {
2250         .owner  = THIS_MODULE,
2251         .open   = fib_triestat_seq_open,
2252         .read   = seq_read,
2253         .llseek = seq_lseek,
2254         .release = single_release_net,
2255 };
2256 
2257 static struct key_vector *fib_trie_get_idx(struct seq_file *seq, loff_t pos)
2258 {
2259         struct fib_trie_iter *iter = seq->private;
2260         struct net *net = seq_file_net(seq);
2261         loff_t idx = 0;
2262         unsigned int h;
2263 
2264         for (h = 0; h < FIB_TABLE_HASHSZ; h++) {
2265                 struct hlist_head *head = &net->ipv4.fib_table_hash[h];
2266                 struct fib_table *tb;
2267 
2268                 hlist_for_each_entry_rcu(tb, head, tb_hlist) {
2269                         struct key_vector *n;
2270 
2271                         for (n = fib_trie_get_first(iter,
2272                                                     (struct trie *) tb->tb_data);
2273                              n; n = fib_trie_get_next(iter))
2274                                 if (pos == idx++) {
2275                                         iter->tb = tb;
2276                                         return n;
2277                                 }
2278                 }
2279         }
2280 
2281         return NULL;
2282 }
2283 
2284 static void *fib_trie_seq_start(struct seq_file *seq, loff_t *pos)
2285         __acquires(RCU)
2286 {
2287         rcu_read_lock();
2288         return fib_trie_get_idx(seq, *pos);
2289 }
2290 
2291 static void *fib_trie_seq_next(struct seq_file *seq, void *v, loff_t *pos)
2292 {
2293         struct fib_trie_iter *iter = seq->private;
2294         struct net *net = seq_file_net(seq);
2295         struct fib_table *tb = iter->tb;
2296         struct hlist_node *tb_node;
2297         unsigned int h;
2298         struct key_vector *n;
2299 
2300         ++*pos;
2301         /* next node in same table */
2302         n = fib_trie_get_next(iter);
2303         if (n)
2304                 return n;
2305 
2306         /* walk rest of this hash chain */
2307         h = tb->tb_id & (FIB_TABLE_HASHSZ - 1);
2308         while ((tb_node = rcu_dereference(hlist_next_rcu(&tb->tb_hlist)))) {
2309                 tb = hlist_entry(tb_node, struct fib_table, tb_hlist);
2310                 n = fib_trie_get_first(iter, (struct trie *) tb->tb_data);
2311                 if (n)
2312                         goto found;
2313         }
2314 
2315         /* new hash chain */
2316         while (++h < FIB_TABLE_HASHSZ) {
2317                 struct hlist_head *head = &net->ipv4.fib_table_hash[h];
2318                 hlist_for_each_entry_rcu(tb, head, tb_hlist) {
2319                         n = fib_trie_get_first(iter, (struct trie *) tb->tb_data);
2320                         if (n)
2321                                 goto found;
2322                 }
2323         }
2324         return NULL;
2325 
2326 found:
2327         iter->tb = tb;
2328         return n;
2329 }
2330 
2331 static void fib_trie_seq_stop(struct seq_file *seq, void *v)
2332         __releases(RCU)
2333 {
2334         rcu_read_unlock();
2335 }
2336 
2337 static void seq_indent(struct seq_file *seq, int n)
2338 {
2339         while (n-- > 0)
2340                 seq_puts(seq, "   ");
2341 }
2342 
2343 static inline const char *rtn_scope(char *buf, size_t len, enum rt_scope_t s)
2344 {
2345         switch (s) {
2346         case RT_SCOPE_UNIVERSE: return "universe";
2347         case RT_SCOPE_SITE:     return "site";
2348         case RT_SCOPE_LINK:     return "link";
2349         case RT_SCOPE_HOST:     return "host";
2350         case RT_SCOPE_NOWHERE:  return "nowhere";
2351         default:
2352                 snprintf(buf, len, "scope=%d", s);
2353                 return buf;
2354         }
2355 }
2356 
2357 static const char *const rtn_type_names[__RTN_MAX] = {
2358         [RTN_UNSPEC] = "UNSPEC",
2359         [RTN_UNICAST] = "UNICAST",
2360         [RTN_LOCAL] = "LOCAL",
2361         [RTN_BROADCAST] = "BROADCAST",
2362         [RTN_ANYCAST] = "ANYCAST",
2363         [RTN_MULTICAST] = "MULTICAST",
2364         [RTN_BLACKHOLE] = "BLACKHOLE",
2365         [RTN_UNREACHABLE] = "UNREACHABLE",
2366         [RTN_PROHIBIT] = "PROHIBIT",
2367         [RTN_THROW] = "THROW",
2368         [RTN_NAT] = "NAT",
2369         [RTN_XRESOLVE] = "XRESOLVE",
2370 };
2371 
2372 static inline const char *rtn_type(char *buf, size_t len, unsigned int t)
2373 {
2374         if (t < __RTN_MAX && rtn_type_names[t])
2375                 return rtn_type_names[t];
2376         snprintf(buf, len, "type %u", t);
2377         return buf;
2378 }
2379 
2380 /* Pretty print the trie */
2381 static int fib_trie_seq_show(struct seq_file *seq, void *v)
2382 {
2383         const struct fib_trie_iter *iter = seq->private;
2384         struct key_vector *n = v;
2385 
2386         if (IS_TRIE(node_parent_rcu(n)))
2387                 fib_table_print(seq, iter->tb);
2388 
2389         if (IS_TNODE(n)) {
2390                 __be32 prf = htonl(n->key);
2391 
2392                 seq_indent(seq, iter->depth-1);
2393                 seq_printf(seq, "  +-- %pI4/%zu %u %u %u\n",
2394                            &prf, KEYLENGTH - n->pos - n->bits, n->bits,
2395                            tn_info(n)->full_children,
2396                            tn_info(n)->empty_children);
2397         } else {
2398                 __be32 val = htonl(n->key);
2399                 struct fib_alias *fa;
2400 
2401                 seq_indent(seq, iter->depth);
2402                 seq_printf(seq, "  |-- %pI4\n", &val);
2403 
2404                 hlist_for_each_entry_rcu(fa, &n->leaf, fa_list) {
2405                         char buf1[32], buf2[32];
2406 
2407                         seq_indent(seq, iter->depth + 1);
2408                         seq_printf(seq, "  /%zu %s %s",
2409                                    KEYLENGTH - fa->fa_slen,
2410                                    rtn_scope(buf1, sizeof(buf1),
2411                                              fa->fa_info->fib_scope),
2412                                    rtn_type(buf2, sizeof(buf2),
2413                                             fa->fa_type));
2414                         if (fa->fa_tos)
2415                                 seq_printf(seq, " tos=%d", fa->fa_tos);
2416                         seq_putc(seq, '\n');
2417                 }
2418         }
2419 
2420         return 0;
2421 }
2422 
2423 static const struct seq_operations fib_trie_seq_ops = {
2424         .start  = fib_trie_seq_start,
2425         .next   = fib_trie_seq_next,
2426         .stop   = fib_trie_seq_stop,
2427         .show   = fib_trie_seq_show,
2428 };
2429 
2430 static int fib_trie_seq_open(struct inode *inode, struct file *file)
2431 {
2432         return seq_open_net(inode, file, &fib_trie_seq_ops,
2433                             sizeof(struct fib_trie_iter));
2434 }
2435 
2436 static const struct file_operations fib_trie_fops = {
2437         .owner  = THIS_MODULE,
2438         .open   = fib_trie_seq_open,
2439         .read   = seq_read,
2440         .llseek = seq_lseek,
2441         .release = seq_release_net,
2442 };
2443 
2444 struct fib_route_iter {
2445         struct seq_net_private p;
2446         struct fib_table *main_tb;
2447         struct key_vector *tnode;
2448         loff_t  pos;
2449         t_key   key;
2450 };
2451 
2452 static struct key_vector *fib_route_get_idx(struct fib_route_iter *iter,
2453                                             loff_t pos)
2454 {
2455         struct fib_table *tb = iter->main_tb;
2456         struct key_vector *l, **tp = &iter->tnode;
2457         struct trie *t;
2458         t_key key;
2459 
2460         /* use cache location of next-to-find key */
2461         if (iter->pos > 0 && pos >= iter->pos) {
2462                 pos -= iter->pos;
2463                 key = iter->key;
2464         } else {
2465                 t = (struct trie *)tb->tb_data;
2466                 iter->tnode = t->kv;
2467                 iter->pos = 0;
2468                 key = 0;
2469         }
2470 
2471         while ((l = leaf_walk_rcu(tp, key)) != NULL) {
2472                 key = l->key + 1;
2473                 iter->pos++;
2474 
2475                 if (--pos <= 0)
2476                         break;
2477 
2478                 l = NULL;
2479 
2480                 /* handle unlikely case of a key wrap */
2481                 if (!key)
2482                         break;
2483         }
2484 
2485         if (l)
2486                 iter->key = key;        /* remember it */
2487         else
2488                 iter->pos = 0;          /* forget it */
2489 
2490         return l;
2491 }
2492 
2493 static void *fib_route_seq_start(struct seq_file *seq, loff_t *pos)
2494         __acquires(RCU)
2495 {
2496         struct fib_route_iter *iter = seq->private;
2497         struct fib_table *tb;
2498         struct trie *t;
2499 
2500         rcu_read_lock();
2501 
2502         tb = fib_get_table(seq_file_net(seq), RT_TABLE_MAIN);
2503         if (!tb)
2504                 return NULL;
2505 
2506         iter->main_tb = tb;
2507 
2508         if (*pos != 0)
2509                 return fib_route_get_idx(iter, *pos);
2510 
2511         t = (struct trie *)tb->tb_data;
2512         iter->tnode = t->kv;
2513         iter->pos = 0;
2514         iter->key = 0;
2515 
2516         return SEQ_START_TOKEN;
2517 }
2518 
2519 static void *fib_route_seq_next(struct seq_file *seq, void *v, loff_t *pos)
2520 {
2521         struct fib_route_iter *iter = seq->private;
2522         struct key_vector *l = NULL;
2523         t_key key = iter->key;
2524 
2525         ++*pos;
2526 
2527         /* only allow key of 0 for start of sequence */
2528         if ((v == SEQ_START_TOKEN) || key)
2529                 l = leaf_walk_rcu(&iter->tnode, key);
2530 
2531         if (l) {
2532                 iter->key = l->key + 1;
2533                 iter->pos++;
2534         } else {
2535                 iter->pos = 0;
2536         }
2537 
2538         return l;
2539 }
2540 
2541 static void fib_route_seq_stop(struct seq_file *seq, void *v)
2542         __releases(RCU)
2543 {
2544         rcu_read_unlock();
2545 }
2546 
2547 static unsigned int fib_flag_trans(int type, __be32 mask, const struct fib_info *fi)
2548 {
2549         unsigned int flags = 0;
2550 
2551         if (type == RTN_UNREACHABLE || type == RTN_PROHIBIT)
2552                 flags = RTF_REJECT;
2553         if (fi && fi->fib_nh->nh_gw)
2554                 flags |= RTF_GATEWAY;
2555         if (mask == htonl(0xFFFFFFFF))
2556                 flags |= RTF_HOST;
2557         flags |= RTF_UP;
2558         return flags;
2559 }
2560 
2561 /*
2562  *      This outputs /proc/net/route.
2563  *      The format of the file is not supposed to be changed
2564  *      and needs to be same as fib_hash output to avoid breaking
2565  *      legacy utilities
2566  */
2567 static int fib_route_seq_show(struct seq_file *seq, void *v)
2568 {
2569         struct fib_route_iter *iter = seq->private;
2570         struct fib_table *tb = iter->main_tb;
2571         struct fib_alias *fa;
2572         struct key_vector *l = v;
2573         __be32 prefix;
2574 
2575         if (v == SEQ_START_TOKEN) {
2576                 seq_printf(seq, "%-127s\n", "Iface\tDestination\tGateway "
2577                            "\tFlags\tRefCnt\tUse\tMetric\tMask\t\tMTU"
2578                            "\tWindow\tIRTT");
2579                 return 0;
2580         }
2581 
2582         prefix = htonl(l->key);
2583 
2584         hlist_for_each_entry_rcu(fa, &l->leaf, fa_list) {
2585                 const struct fib_info *fi = fa->fa_info;
2586                 __be32 mask = inet_make_mask(KEYLENGTH - fa->fa_slen);
2587                 unsigned int flags = fib_flag_trans(fa->fa_type, mask, fi);
2588 
2589                 if ((fa->fa_type == RTN_BROADCAST) ||
2590                     (fa->fa_type == RTN_MULTICAST))
2591                         continue;
2592 
2593                 if (fa->tb_id != tb->tb_id)
2594                         continue;
2595 
2596                 seq_setwidth(seq, 127);
2597 
2598                 if (fi)
2599                         seq_printf(seq,
2600                                    "%s\t%08X\t%08X\t%04X\t%d\t%u\t"
2601                                    "%d\t%08X\t%d\t%u\t%u",
2602                                    fi->fib_dev ? fi->fib_dev->name : "*",
2603                                    prefix,
2604                                    fi->fib_nh->nh_gw, flags, 0, 0,
2605                                    fi->fib_priority,
2606                                    mask,
2607                                    (fi->fib_advmss ?
2608                                     fi->fib_advmss + 40 : 0),
2609                                    fi->fib_window,
2610                                    fi->fib_rtt >> 3);
2611                 else
2612                         seq_printf(seq,
2613                                    "*\t%08X\t%08X\t%04X\t%d\t%u\t"
2614                                    "%d\t%08X\t%d\t%u\t%u",
2615                                    prefix, 0, flags, 0, 0, 0,
2616                                    mask, 0, 0, 0);
2617 
2618                 seq_pad(seq, '\n');
2619         }
2620 
2621         return 0;
2622 }
2623 
2624 static const struct seq_operations fib_route_seq_ops = {
2625         .start  = fib_route_seq_start,
2626         .next   = fib_route_seq_next,
2627         .stop   = fib_route_seq_stop,
2628         .show   = fib_route_seq_show,
2629 };
2630 
2631 static int fib_route_seq_open(struct inode *inode, struct file *file)
2632 {
2633         return seq_open_net(inode, file, &fib_route_seq_ops,
2634                             sizeof(struct fib_route_iter));
2635 }
2636 
2637 static const struct file_operations fib_route_fops = {
2638         .owner  = THIS_MODULE,
2639         .open   = fib_route_seq_open,
2640         .read   = seq_read,
2641         .llseek = seq_lseek,
2642         .release = seq_release_net,
2643 };
2644 
2645 int __net_init fib_proc_init(struct net *net)
2646 {
2647         if (!proc_create("fib_trie", S_IRUGO, net->proc_net, &fib_trie_fops))
2648                 goto out1;
2649 
2650         if (!proc_create("fib_triestat", S_IRUGO, net->proc_net,
2651                          &fib_triestat_fops))
2652                 goto out2;
2653 
2654         if (!proc_create("route", S_IRUGO, net->proc_net, &fib_route_fops))
2655                 goto out3;
2656 
2657         return 0;
2658 
2659 out3:
2660         remove_proc_entry("fib_triestat", net->proc_net);
2661 out2:
2662         remove_proc_entry("fib_trie", net->proc_net);
2663 out1:
2664         return -ENOMEM;
2665 }
2666 
2667 void __net_exit fib_proc_exit(struct net *net)
2668 {
2669         remove_proc_entry("fib_trie", net->proc_net);
2670         remove_proc_entry("fib_triestat", net->proc_net);
2671         remove_proc_entry("route", net->proc_net);
2672 }
2673 
2674 #endif /* CONFIG_PROC_FS */
2675 

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