[IPV4]: Add LC-Trie FIB lookup algorithm.

Signed-off-by: Robert Olsson <Robert.Olsson@data.slu.se>
Signed-off-by: David S. Miller <davem@davemloft.net>

4 files changed, 2495 insertions, 1 deletions

diff --git a/net/ipv4/Kconfig b/net/ipv4/Kconfig
index 6d3e8b1bd1f..05107e0dc14 100644
--- a/net/ipv4/Kconfig
+++ b/net/ipv4/Kconfig
@@ -1,6 +1,32 @@
 #
 # IP configuration
 #
+choice 
+	prompt "Choose IP: FIB lookup""
+	depends on INET
+	default IP_FIB_HASH
+
+config IP_FIB_HASH
+	bool "FIB_HASH"
+	---help---
+	Current FIB is very proven and good enough for most users.
+
+config IP_FIB_TRIE
+	bool "FIB_TRIE"
+	---help---
+	Use new experimental LC-trie as FIB lookup algoritm. 
+        This improves lookup performance
+	
+	LC-trie is described in:
+	
+ 	IP-address lookup using LC-tries. Stefan Nilsson and Gunnar Karlsson
+ 	IEEE Journal on Selected Areas in Communications, 17(6):1083-1092, June 1999
+	An experimental study of compression methods for dynamic tries
+ 	Stefan Nilsson and Matti Tikkanen. Algorithmica, 33(1):19-33, 2002.
+ 	http://www.nada.kth.se/~snilsson/public/papers/dyntrie2/
+       
+endchoice
+
 config IP_MULTICAST
 	bool "IP: multicasting"
 	depends on INET
diff --git a/net/ipv4/Makefile b/net/ipv4/Makefile
index 8b379627ebb..65d57d8e1ad 100644
--- a/net/ipv4/Makefile
+++ b/net/ipv4/Makefile
@@ -7,8 +7,10 @@ obj-y     := utils.o route.o inetpeer.o protocol.o \
 	     ip_output.o ip_sockglue.o \
 	     tcp.o tcp_input.o tcp_output.o tcp_timer.o tcp_ipv4.o tcp_minisocks.o \
 	     datagram.o raw.o udp.o arp.o icmp.o devinet.o af_inet.o igmp.o \
-	     sysctl_net_ipv4.o fib_frontend.o fib_semantics.o fib_hash.o
+	     sysctl_net_ipv4.o fib_frontend.o fib_semantics.o
 
+obj-$(CONFIG_IP_FIB_HASH) += fib_hash.o
+obj-$(CONFIG_IP_FIB_TRIE) += fib_trie.o
 obj-$(CONFIG_PROC_FS) += proc.o
 obj-$(CONFIG_IP_MULTIPLE_TABLES) += fib_rules.o
 obj-$(CONFIG_IP_MROUTE) += ipmr.o
diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c
index 03942f13394..658e7977924 100644
--- a/net/ipv4/af_inet.c
+++ b/net/ipv4/af_inet.c
@@ -1119,6 +1119,10 @@ module_init(inet_init);
 #ifdef CONFIG_PROC_FS
 extern int  fib_proc_init(void);
 extern void fib_proc_exit(void);
+#ifdef CONFIG_IP_FIB_TRIE
+extern int  fib_stat_proc_init(void);
+extern void fib_stat_proc_exit(void);
+#endif
 extern int  ip_misc_proc_init(void);
 extern int  raw_proc_init(void);
 extern void raw_proc_exit(void);
@@ -1139,11 +1143,19 @@ static int __init ipv4_proc_init(void)
 		goto out_udp;
 	if (fib_proc_init())
 		goto out_fib;
+#ifdef CONFIG_IP_FIB_TRIE
+         if (fib_stat_proc_init())
+                 goto out_fib_stat;
+ #endif
 	if (ip_misc_proc_init())
 		goto out_misc;
 out:
 	return rc;
 out_misc:
+#ifdef CONFIG_IP_FIB_TRIE
+ 	fib_stat_proc_exit();
+out_fib_stat:
+#endif
 	fib_proc_exit();
 out_fib:
 	udp4_proc_exit();
diff --git a/net/ipv4/fib_trie.c b/net/ipv4/fib_trie.c
new file mode 100644
index 00000000000..c0ece94fc63
--- /dev/null
+++ b/net/ipv4/fib_trie.c
@@ -0,0 +1,2454 @@
+/*
+ *   This program is free software; you can redistribute it and/or
+ *   modify it under the terms of the GNU General Public License
+ *   as published by the Free Software Foundation; either version
+ *   2 of the License, or (at your option) any later version.
+ *
+ *   Robert Olsson <robert.olsson@its.uu.se> Uppsala Universitet
+ *     & Swedish University of Agricultural Sciences.
+ *
+ *   Jens Laas <jens.laas@data.slu.se> Swedish University of 
+ *     Agricultural Sciences.
+ * 
+ *   Hans Liss <hans.liss@its.uu.se>  Uppsala Universitet
+ *
+ * This work is based on the LPC-trie which is originally descibed in:
+ * 
+ * An experimental study of compression methods for dynamic tries
+ * Stefan Nilsson and Matti Tikkanen. Algorithmica, 33(1):19-33, 2002.
+ * http://www.nada.kth.se/~snilsson/public/papers/dyntrie2/
+ *
+ *
+ * IP-address lookup using LC-tries. Stefan Nilsson and Gunnar Karlsson
+ * IEEE Journal on Selected Areas in Communications, 17(6):1083-1092, June 1999
+ *
+ * Version:	$Id: fib_trie.c,v 1.3 2005/06/08 14:20:01 robert Exp $
+ *
+ *
+ * Code from fib_hash has been reused which includes the following header:
+ *
+ *
+ * INET		An implementation of the TCP/IP protocol suite for the LINUX
+ *		operating system.  INET is implemented using the  BSD Socket
+ *		interface as the means of communication with the user level.
+ *
+ *		IPv4 FIB: lookup engine and maintenance routines.
+ *
+ *
+ * Authors:	Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
+ *
+ *		This program is free software; you can redistribute it and/or
+ *		modify it under the terms of the GNU General Public License
+ *		as published by the Free Software Foundation; either version
+ *		2 of the License, or (at your option) any later version.
+ */
+
+#define VERSION "0.323"
+
+#include <linux/config.h>
+#include <asm/uaccess.h>
+#include <asm/system.h>
+#include <asm/bitops.h>
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/mm.h>
+#include <linux/string.h>
+#include <linux/socket.h>
+#include <linux/sockios.h>
+#include <linux/errno.h>
+#include <linux/in.h>
+#include <linux/inet.h>
+#include <linux/netdevice.h>
+#include <linux/if_arp.h>
+#include <linux/proc_fs.h>
+#include <linux/skbuff.h>
+#include <linux/netlink.h>
+#include <linux/init.h>
+#include <linux/list.h>
+#include <net/ip.h>
+#include <net/protocol.h>
+#include <net/route.h>
+#include <net/tcp.h>
+#include <net/sock.h>
+#include <net/ip_fib.h>
+#include "fib_lookup.h"
+
+#undef CONFIG_IP_FIB_TRIE_STATS
+#define MAX_CHILDS 16384
+
+#define EXTRACT(p, n, str) ((str)<<(p)>>(32-(n)))
+#define KEYLENGTH (8*sizeof(t_key))
+#define MASK_PFX(k, l) (((l)==0)?0:(k >> (KEYLENGTH-l)) << (KEYLENGTH-l))
+#define TKEY_GET_MASK(offset, bits) (((bits)==0)?0:((t_key)(-1) << (KEYLENGTH - bits) >> offset))
+
+static DEFINE_RWLOCK(fib_lock);
+
+typedef unsigned int t_key;
+
+#define T_TNODE 0
+#define T_LEAF  1
+#define NODE_TYPE_MASK	0x1UL
+#define NODE_PARENT(_node) \
+((struct tnode *)((_node)->_parent & ~NODE_TYPE_MASK))
+#define NODE_SET_PARENT(_node, _ptr) \
+((_node)->_parent = (((unsigned long)(_ptr)) | \
+                     ((_node)->_parent & NODE_TYPE_MASK)))
+#define NODE_INIT_PARENT(_node, _type) \
+((_node)->_parent = (_type))
+#define NODE_TYPE(_node) \
+((_node)->_parent & NODE_TYPE_MASK)
+
+#define IS_TNODE(n) (!(n->_parent & T_LEAF))
+#define IS_LEAF(n) (n->_parent & T_LEAF)
+
+struct node {
+        t_key key;
+	unsigned long _parent;
+};
+
+struct leaf {
+        t_key key;
+	unsigned long _parent;
+	struct hlist_head list;
+};
+
+struct leaf_info {
+	struct hlist_node hlist;
+	int plen;
+	struct list_head falh;
+};
+
+struct tnode {
+        t_key key;
+	unsigned long _parent;
+        unsigned short pos:5;        /* 2log(KEYLENGTH) bits needed */
+        unsigned short bits:5;       /* 2log(KEYLENGTH) bits needed */
+        unsigned short full_children;  /* KEYLENGTH bits needed */
+        unsigned short empty_children; /* KEYLENGTH bits needed */
+        struct node *child[0];
+};
+
+#ifdef CONFIG_IP_FIB_TRIE_STATS
+struct trie_use_stats {
+	unsigned int gets;
+	unsigned int backtrack;
+	unsigned int semantic_match_passed;
+	unsigned int semantic_match_miss;
+	unsigned int null_node_hit;
+};
+#endif
+
+struct trie_stat {
+	unsigned int totdepth;
+	unsigned int maxdepth;
+	unsigned int tnodes;
+	unsigned int leaves;
+	unsigned int nullpointers;
+	unsigned int nodesizes[MAX_CHILDS];
+};    
+
+struct trie {
+        struct node *trie;
+#ifdef CONFIG_IP_FIB_TRIE_STATS
+	struct trie_use_stats stats;
+#endif
+        int size;
+	unsigned int revision;
+};
+
+static int trie_debug = 0;
+
+static int tnode_full(struct tnode *tn, struct node *n);
+static void put_child(struct trie *t, struct tnode *tn, int i, struct node *n);
+static void tnode_put_child_reorg(struct tnode *tn, int i, struct node *n, int wasfull);
+static int tnode_child_length(struct tnode *tn);
+static struct node *resize(struct trie *t, struct tnode *tn);
+static struct tnode *inflate(struct trie *t, struct tnode *tn);
+static struct tnode *halve(struct trie *t, struct tnode *tn);
+static void tnode_free(struct tnode *tn);
+static void trie_dump_seq(struct seq_file *seq, struct trie *t);
+extern struct fib_alias *fib_find_alias(struct list_head *fah, u8 tos, u32 prio);
+extern int fib_detect_death(struct fib_info *fi, int order,
+                            struct fib_info **last_resort, int *last_idx, int *dflt);
+
+extern void rtmsg_fib(int event, u32 key, struct fib_alias *fa, int z, int tb_id,
+               struct nlmsghdr *n, struct netlink_skb_parms *req);
+
+static kmem_cache_t *fn_alias_kmem;
+static struct trie *trie_local = NULL, *trie_main = NULL;
+
+static void trie_bug(char *err)
+{
+	printk("Trie Bug: %s\n", err);
+	BUG();
+}
+
+static inline struct node *tnode_get_child(struct tnode *tn, int i) 
+{
+        if (i >=  1<<tn->bits) 
+                trie_bug("tnode_get_child");
+
+        return tn->child[i];
+}
+
+static inline int tnode_child_length(struct tnode *tn)
+{
+        return 1<<tn->bits;
+}
+
+/*
+  _________________________________________________________________
+  | i | i | i | i | i | i | i | N | N | N | S | S | S | S | S | C |
+  ----------------------------------------------------------------
+    0   1   2   3   4   5   6   7   8   9  10  11  12  13  14  15 
+
+  _________________________________________________________________
+  | C | C | C | u | u | u | u | u | u | u | u | u | u | u | u | u |
+  -----------------------------------------------------------------
+   16  17  18  19  20  21  22  23  24  25  26  27  28  29  30  31
+
+  tp->pos = 7
+  tp->bits = 3
+  n->pos = 15
+  n->bits=4
+  KEYLENGTH=32
+*/
+
+static inline t_key tkey_extract_bits(t_key a, int offset, int bits)
+{
+        if (offset < KEYLENGTH)
+		return ((t_key)(a << offset)) >> (KEYLENGTH - bits);
+        else
+		return 0;
+}
+
+static inline int tkey_equals(t_key a, t_key b)
+{
+  return a == b;
+}
+
+static inline int tkey_sub_equals(t_key a, int offset, int bits, t_key b)
+{
+     if (bits == 0 || offset >= KEYLENGTH)
+            return 1;
+        bits = bits > KEYLENGTH ? KEYLENGTH : bits;
+        return ((a ^ b) << offset) >> (KEYLENGTH - bits) == 0;
+}	
+
+static inline int tkey_mismatch(t_key a, int offset, t_key b)
+{
+	t_key diff = a ^ b;
+	int i = offset;
+
+	if(!diff) 
+	  return 0;
+	while((diff << i) >> (KEYLENGTH-1) == 0)
+		i++;
+	return i;
+}
+
+/* Candiate for fib_semantics */
+
+static void fn_free_alias(struct fib_alias *fa)
+{
+	fib_release_info(fa->fa_info);
+	kmem_cache_free(fn_alias_kmem, fa);
+}
+
+/*
+  To understand this stuff, an understanding of keys and all their bits is 
+  necessary. Every node in the trie has a key associated with it, but not 
+  all of the bits in that key are significant.
+
+  Consider a node 'n' and its parent 'tp'.
+
+  If n is a leaf, every bit in its key is significant. Its presence is 
+  necessitaded by path compression, since during a tree traversal (when 
+  searching for a leaf - unless we are doing an insertion) we will completely 
+  ignore all skipped bits we encounter. Thus we need to verify, at the end of 
+  a potentially successful search, that we have indeed been walking the 
+  correct key path.
+
+  Note that we can never "miss" the correct key in the tree if present by 
+  following the wrong path. Path compression ensures that segments of the key 
+  that are the same for all keys with a given prefix are skipped, but the 
+  skipped part *is* identical for each node in the subtrie below the skipped 
+  bit! trie_insert() in this implementation takes care of that - note the 
+  call to tkey_sub_equals() in trie_insert().
+
+  if n is an internal node - a 'tnode' here, the various parts of its key 
+  have many different meanings.
+
+  Example:  
+  _________________________________________________________________
+  | i | i | i | i | i | i | i | N | N | N | S | S | S | S | S | C |
+  -----------------------------------------------------------------
+    0   1   2   3   4   5   6   7   8   9  10  11  12  13  14  15 
+
+  _________________________________________________________________
+  | C | C | C | u | u | u | u | u | u | u | u | u | u | u | u | u |
+  -----------------------------------------------------------------
+   16  17  18  19  20  21  22  23  24  25  26  27  28  29  30  31
+
+  tp->pos = 7
+  tp->bits = 3
+  n->pos = 15
+  n->bits=4
+
+  First, let's just ignore the bits that come before the parent tp, that is 
+  the bits from 0 to (tp->pos-1). They are *known* but at this point we do 
+  not use them for anything.
+
+  The bits from (tp->pos) to (tp->pos + tp->bits - 1) - "N", above - are the
+  index into the parent's child array. That is, they will be used to find 
+  'n' among tp's children.
+
+  The bits from (tp->pos + tp->bits) to (n->pos - 1) - "S" - are skipped bits
+  for the node n.
+
+  All the bits we have seen so far are significant to the node n. The rest 
+  of the bits are really not needed or indeed known in n->key.
+
+  The bits from (n->pos) to (n->pos + n->bits - 1) - "C" - are the index into 
+  n's child array, and will of course be different for each child.
+  
+  The rest of the bits, from (n->pos + n->bits) onward, are completely unknown
+  at this point.
+
+*/
+
+static void check_tnode(struct tnode *tn)
+{
+	if(tn && tn->pos+tn->bits > 32) {
+		printk("TNODE ERROR tn=%p, pos=%d, bits=%d\n", tn, tn->pos, tn->bits);
+	}
+}
+
+static int halve_threshold = 25;
+static int inflate_threshold = 50;
+
+static struct leaf *leaf_new(void)
+{
+	struct leaf *l = kmalloc(sizeof(struct leaf),  GFP_KERNEL);
+	if(l) {
+		NODE_INIT_PARENT(l, T_LEAF);
+		INIT_HLIST_HEAD(&l->list);
+	}
+	return l;
+}
+
+static struct leaf_info *leaf_info_new(int plen)
+{
+	struct leaf_info *li = kmalloc(sizeof(struct leaf_info),  GFP_KERNEL);
+	li->plen = plen;
+	INIT_LIST_HEAD(&li->falh);
+	return li;
+}
+
+static inline void free_leaf(struct leaf *l)
+{
+	kfree(l);
+}
+
+static inline void free_leaf_info(struct leaf_info *li)
+{
+	kfree(li);
+}
+
+static struct tnode* tnode_new(t_key key, int pos, int bits)
+{
+	int nchildren = 1<<bits;
+	int sz = sizeof(struct tnode) + nchildren * sizeof(struct node *);
+	struct tnode *tn = kmalloc(sz,  GFP_KERNEL);
+
+	if(tn)  {
+		memset(tn, 0, sz);
+		NODE_INIT_PARENT(tn, T_TNODE);
+		tn->pos = pos;
+		tn->bits = bits;
+		tn->key = key;
+		tn->full_children = 0;
+		tn->empty_children = 1<<bits;
+	}
+	if(trie_debug > 0) 
+		printk("AT %p s=%u %u\n", tn, (unsigned int) sizeof(struct tnode),
+		       (unsigned int) (sizeof(struct node) * 1<<bits));
+	return tn;
+}
+
+static void tnode_free(struct tnode *tn)
+{
+	if(!tn) {
+		trie_bug("tnode_free\n");
+	}
+	if(IS_LEAF(tn)) {
+		free_leaf((struct leaf *)tn);
+		if(trie_debug > 0 ) 
+			printk("FL %p \n", tn);
+	}
+	else if(IS_TNODE(tn)) { 
+		kfree(tn);
+		if(trie_debug > 0 ) 
+			printk("FT %p \n", tn);
+	}
+	else {
+		trie_bug("tnode_free\n");
+	}
+}
+
+/*
+ * Check whether a tnode 'n' is "full", i.e. it is an internal node
+ * and no bits are skipped. See discussion in dyntree paper p. 6
+ */
+
+static inline int tnode_full(struct tnode *tn, struct node *n)
+{
+	if(n == NULL || IS_LEAF(n))
+		return 0;
+
+	return ((struct tnode *) n)->pos == tn->pos + tn->bits;
+}
+
+static inline void put_child(struct trie *t, struct tnode *tn, int i, struct node *n) 
+{
+	tnode_put_child_reorg(tn, i, n, -1);
+}
+
+ /* 
+  * Add a child at position i overwriting the old value.
+  * Update the value of full_children and empty_children.
+  */
+
+static void tnode_put_child_reorg(struct tnode *tn, int i, struct node *n, int wasfull) 
+{
+	struct node *chi;
+	int isfull;
+
+	if(i >=  1<<tn->bits) {
+		printk("bits=%d, i=%d\n", tn->bits, i);
+		trie_bug("tnode_put_child_reorg bits");
+	}
+	write_lock_bh(&fib_lock);
+	chi = tn->child[i];	
+
+	/* update emptyChildren */
+	if (n == NULL && chi != NULL)
+		tn->empty_children++;
+	else if (n != NULL && chi == NULL)
+		tn->empty_children--;
+  
+	/* update fullChildren */
+        if (wasfull == -1)
+		wasfull = tnode_full(tn, chi);
+
+	isfull = tnode_full(tn, n);
+	if (wasfull && !isfull) 
+		tn->full_children--;
+	
+	else if (!wasfull && isfull) 
+		tn->full_children++;
+	if(n) 
+		NODE_SET_PARENT(n, tn);	
+
+	tn->child[i] = n;
+	write_unlock_bh(&fib_lock);
+}
+
+static struct node *resize(struct trie *t, struct tnode *tn) 
+{
+	int i;
+
+ 	if (!tn)
+		return NULL;
+
+	if(trie_debug) 
+		printk("In tnode_resize %p inflate_threshold=%d threshold=%d\n", 
+		      tn, inflate_threshold, halve_threshold);
+
+	/* No children */
+	if (tn->empty_children == tnode_child_length(tn)) {
+		tnode_free(tn);
+		return NULL;
+	}
+	/* One child */
+	if (tn->empty_children == tnode_child_length(tn) - 1)
+		for (i = 0; i < tnode_child_length(tn); i++) {
+
+			write_lock_bh(&fib_lock);
+			if (tn->child[i] != NULL) {
+
+				/* compress one level */
+				struct node *n = tn->child[i];
+				if(n)
+					NODE_INIT_PARENT(n, NODE_TYPE(n));
+
+				write_unlock_bh(&fib_lock);
+				tnode_free(tn);
+				return n;
+			}
+			write_unlock_bh(&fib_lock);
+		}
+	/* 
+	 * Double as long as the resulting node has a number of
+	 * nonempty nodes that are above the threshold.
+	 */
+
+	/*
+	 * From "Implementing a dynamic compressed trie" by Stefan Nilsson of 
+	 * the Helsinki University of Technology and Matti Tikkanen of Nokia 
+	 * Telecommunications, page 6:
+	 * "A node is doubled if the ratio of non-empty children to all 
+	 * children in the *doubled* node is at least 'high'."
+	 *
+	 * 'high' in this instance is the variable 'inflate_threshold'. It 
+	 * is expressed as a percentage, so we multiply it with 
+	 * tnode_child_length() and instead of multiplying by 2 (since the 
+	 * child array will be doubled by inflate()) and multiplying 
+	 * the left-hand side by 100 (to handle the percentage thing) we 
+	 * multiply the left-hand side by 50.
+	 * 
+	 * The left-hand side may look a bit weird: tnode_child_length(tn) 
+	 * - tn->empty_children is of course the number of non-null children 
+	 * in the current node. tn->full_children is the number of "full" 
+	 * children, that is non-null tnodes with a skip value of 0.
+	 * All of those will be doubled in the resulting inflated tnode, so 
+	 * we just count them one extra time here.
+	 * 
+	 * A clearer way to write this would be:
+	 * 
+	 * to_be_doubled = tn->full_children;
+	 * not_to_be_doubled = tnode_child_length(tn) - tn->empty_children - 
+	 *     tn->full_children;
+	 *
+	 * new_child_length = tnode_child_length(tn) * 2;
+	 *
+	 * new_fill_factor = 100 * (not_to_be_doubled + 2*to_be_doubled) / 
+	 *      new_child_length;
+	 * if (new_fill_factor >= inflate_threshold)
+	 * 
+	 * ...and so on, tho it would mess up the while() loop.
+	 * 
+	 * anyway,
+	 * 100 * (not_to_be_doubled + 2*to_be_doubled) / new_child_length >=
+	 *      inflate_threshold
+	 * 
+	 * avoid a division:
+	 * 100 * (not_to_be_doubled + 2*to_be_doubled) >=
+	 *      inflate_threshold * new_child_length
+	 * 
+	 * expand not_to_be_doubled and to_be_doubled, and shorten:
+	 * 100 * (tnode_child_length(tn) - tn->empty_children + 
+	 *    tn->full_children ) >= inflate_threshold * new_child_length
+	 * 
+	 * expand new_child_length:
+	 * 100 * (tnode_child_length(tn) - tn->empty_children + 
+	 *    tn->full_children ) >=
+	 *      inflate_threshold * tnode_child_length(tn) * 2
+	 * 
+	 * shorten again:
+	 * 50 * (tn->full_children + tnode_child_length(tn) - 
+	 *    tn->empty_children ) >= inflate_threshold * 
+	 *    tnode_child_length(tn)
+	 * 
+	 */
+
+	check_tnode(tn);
+
+	while ((tn->full_children > 0 &&
+	       50 * (tn->full_children + tnode_child_length(tn) - tn->empty_children) >=
+				inflate_threshold * tnode_child_length(tn))) {
+
+		tn = inflate(t, tn);
+	}
+
+	check_tnode(tn);
+
+	/*
+	 * Halve as long as the number of empty children in this
+	 * node is above threshold.
+	 */
+	while (tn->bits > 1 &&
+	       100 * (tnode_child_length(tn) - tn->empty_children) <
+	       halve_threshold * tnode_child_length(tn))
+
+		tn = halve(t, tn);
+  
+	/* Only one child remains */
+
+	if (tn->empty_children == tnode_child_length(tn) - 1)
+		for (i = 0; i < tnode_child_length(tn); i++) {
+			
+			write_lock_bh(&fib_lock);
+			if (tn->child[i] != NULL) {
+				/* compress one level */
+				struct node *n = tn->child[i];
+
+				if(n)
+					NODE_INIT_PARENT(n, NODE_TYPE(n));
+
+				write_unlock_bh(&fib_lock);
+				tnode_free(tn);
+				return n;
+			}
+			write_unlock_bh(&fib_lock);
+		}
+
+	return (struct node *) tn;
+}
+
+static struct tnode *inflate(struct trie *t, struct tnode *tn)
+{
+	struct tnode *inode;
+	struct tnode *oldtnode = tn;
+	int olen = tnode_child_length(tn);
+	int i;
+
+  	if(trie_debug) 
+		printk("In inflate\n");
+
+	tn = tnode_new(oldtnode->key, oldtnode->pos, oldtnode->bits + 1);
+
+	if (!tn)
+		trie_bug("tnode_new failed");
+
+	for(i = 0; i < olen; i++) {
+		struct node *node = tnode_get_child(oldtnode, i);
+      
+		/* An empty child */
+		if (node == NULL)
+			continue;
+
+		/* A leaf or an internal node with skipped bits */
+
+		if(IS_LEAF(node) || ((struct tnode *) node)->pos >
+		   tn->pos + tn->bits - 1) {
+			if(tkey_extract_bits(node->key, tn->pos + tn->bits - 1,
+					     1) == 0)
+				put_child(t, tn, 2*i, node);
+			else
+				put_child(t, tn, 2*i+1, node);
+			continue;
+		}
+
+		/* An internal node with two children */
+		inode = (struct tnode *) node;
+
+		if (inode->bits == 1) {
+			put_child(t, tn, 2*i, inode->child[0]);
+			put_child(t, tn, 2*i+1, inode->child[1]);
+
+			tnode_free(inode);
+		}
+
+			/* An internal node with more than two children */
+		else {
+			struct tnode *left, *right;
+			int size, j;
+
+			/* We will replace this node 'inode' with two new 
+			 * ones, 'left' and 'right', each with half of the 
+			 * original children. The two new nodes will have 
+			 * a position one bit further down the key and this 
+			 * means that the "significant" part of their keys 
+			 * (see the discussion near the top of this file) 
+			 * will differ by one bit, which will be "0" in 
+			 * left's key and "1" in right's key. Since we are 
+			 * moving the key position by one step, the bit that 
+			 * we are moving away from - the bit at position 
+			 * (inode->pos) - is the one that will differ between 
+			 * left and right. So... we synthesize that bit in the
+			 * two  new keys.
+			 * The mask 'm' below will be a single "one" bit at 
+			 * the position (inode->pos)
+			 */
+
+			t_key m = TKEY_GET_MASK(inode->pos, 1);
+ 
+			/* Use the old key, but set the new significant 
+			 *   bit to zero. 
+			 */
+			left = tnode_new(inode->key&(~m), inode->pos + 1,
+					 inode->bits - 1);
+
+			if(!left) 
+				trie_bug("tnode_new failed");
+			
+			
+			/* Use the old key, but set the new significant 
+			 * bit to one. 
+			 */
+			right = tnode_new(inode->key|m, inode->pos + 1,
+					  inode->bits - 1);
+
+			if(!right) 
+				trie_bug("tnode_new failed");
+			
+			size = tnode_child_length(left);
+			for(j = 0; j < size; j++) {
+				put_child(t, left, j, inode->child[j]);
+				put_child(t, right, j, inode->child[j + size]);
+			}
+			put_child(t, tn, 2*i, resize(t, left));
+			put_child(t, tn, 2*i+1, resize(t, right));
+
+			tnode_free(inode);
+		}
+	}
+	tnode_free(oldtnode);
+	return tn;
+}
+
+static struct tnode *halve(struct trie *t, struct tnode *tn)
+{
+	struct tnode *oldtnode = tn;
+	struct node *left, *right;
+	int i;
+	int olen = tnode_child_length(tn);
+
+	if(trie_debug) printk("In halve\n");
+  
+	tn=tnode_new(oldtnode->key, oldtnode->pos, oldtnode->bits - 1);
+
+	if(!tn) 
+		trie_bug("tnode_new failed");
+
+	for(i = 0; i < olen; i += 2) {
+		left = tnode_get_child(oldtnode, i);
+		right = tnode_get_child(oldtnode, i+1);
+    
+		/* At least one of the children is empty */
+		if (left == NULL) {
+			if (right == NULL)    /* Both are empty */
+				continue;
+			put_child(t, tn, i/2, right);
+		} else if (right == NULL)
+			put_child(t, tn, i/2, left);
+     
+		/* Two nonempty children */
+		else {
+			struct tnode *newBinNode =
+				tnode_new(left->key, tn->pos + tn->bits, 1);
+
+			if(!newBinNode) 
+				trie_bug("tnode_new failed");
+
+			put_child(t, newBinNode, 0, left);
+			put_child(t, newBinNode, 1, right);
+			put_child(t, tn, i/2, resize(t, newBinNode));
+		}
+	}
+	tnode_free(oldtnode);
+	return tn;
+}
+
+static void *trie_init(struct trie *t)
+{
+	if(t) {
+		t->size = 0;
+		t->trie = NULL;
+		t->revision = 0;
+#ifdef CONFIG_IP_FIB_TRIE_STATS
+       		memset(&t->stats, 0, sizeof(struct trie_use_stats));
+#endif
+	}
+	return t;
+}
+
+static struct leaf_info *find_leaf_info(struct hlist_head *head, int plen)
+{
+	struct hlist_node *node;
+	struct leaf_info *li;
+
+	hlist_for_each_entry(li, node, head, hlist) {
+		  
+		if ( li->plen == plen )
+			return li;
+	}
+	return NULL;
+}
+
+static inline struct list_head * get_fa_head(struct leaf *l, int plen)
+{
+	struct list_head *fa_head=NULL;
+	struct leaf_info *li = find_leaf_info(&l->list, plen);
+	
+	if(li) 
+		fa_head = &li->falh;
+	
+	return fa_head;
+}
+
+static void insert_leaf_info(struct hlist_head *head, struct leaf_info *new)
+{
+	struct leaf_info *li=NULL, *last=NULL;
+	struct hlist_node *node, *tmp;
+
+	write_lock_bh(&fib_lock);
+	
+	if(hlist_empty(head))
+		hlist_add_head(&new->hlist, head);
+	else {
+		hlist_for_each_entry_safe(li, node, tmp, head, hlist) {
+			
+			if (new->plen > li->plen) 
+				break;
+			
+			last = li;
+		}
+		if(last) 
+			hlist_add_after(&last->hlist, &new->hlist);
+		else 
+			hlist_add_before(&new->hlist, &li->hlist);
+	}
+	write_unlock_bh(&fib_lock);
+}
+
+static struct leaf *
+fib_find_node(struct trie *t, u32 key)
+{
+	int pos;
+	struct tnode *tn;
+	struct node *n;
+
+	pos = 0;
+	n=t->trie;
+
+	while (n != NULL &&  NODE_TYPE(n) == T_TNODE) {
+		tn = (struct tnode *) n;
+			
+		check_tnode(tn);
+			
+		if(tkey_sub_equals(tn->key, pos, tn->pos-pos, key)) {
+			pos=tn->pos + tn->bits;
+			n = tnode_get_child(tn, tkey_extract_bits(key, tn->pos, tn->bits));
+		}
+		else
+			break;
+	}
+	/* Case we have found a leaf. Compare prefixes */
+
+	if (n != NULL && IS_LEAF(n) && tkey_equals(key, n->key)) {
+		struct leaf *l = (struct leaf *) n;
+		return l;
+	}
+	return NULL;
+}
+
+static struct node *trie_rebalance(struct trie *t, struct tnode *tn)
+{
+	int i = 0;
+	int wasfull;
+	t_key cindex, key;
+	struct tnode *tp = NULL;
+
+	if(!tn) 
+		BUG();
+	
+	key = tn->key;
+	i = 0;
+
+	while (tn != NULL && NODE_PARENT(tn) != NULL) {
+
+		if( i > 10 ) {
+			printk("Rebalance tn=%p \n", tn);
+			if(tn) 		printk("tn->parent=%p \n", NODE_PARENT(tn));
+			
+			printk("Rebalance tp=%p \n", tp);
+			if(tp) 		printk("tp->parent=%p \n", NODE_PARENT(tp));
+		}
+
+		if( i > 12 ) BUG();
+		i++;
+
+		tp = NODE_PARENT(tn);
+		cindex = tkey_extract_bits(key, tp->pos, tp->bits);
+		wasfull = tnode_full(tp, tnode_get_child(tp, cindex));
+		tn = (struct tnode *) resize (t, (struct tnode *)tn);
+		tnode_put_child_reorg((struct tnode *)tp, cindex,(struct node*)tn, wasfull);
+		
+		if(!NODE_PARENT(tn))
+			break;
+
+		tn = NODE_PARENT(tn);
+	}
+	/* Handle last (top) tnode */
+	if (IS_TNODE(tn)) 
+		tn = (struct tnode*) resize(t, (struct tnode *)tn);
+
+	return (struct node*) tn;
+}
+
+static struct list_head *
+fib_insert_node(struct trie *t, u32 key, int plen)
+{
+	int pos, newpos;
+	struct tnode *tp = NULL, *tn = NULL;
+	struct node *n;
+	struct leaf *l;
+	int missbit;
+	struct list_head *fa_head=NULL;
+	struct leaf_info *li;
+	t_key cindex;
+
+	pos = 0;
+	n=t->trie;
+
+	/* If we point to NULL, stop. Either the tree is empty and we should 
+	 * just put a new leaf in if, or we have reached an empty child slot, 
+	 * and we should just put our new leaf in that.
+	 * If we point to a T_TNODE, check if it matches our key. Note that 
+	 * a T_TNODE might be skipping any number of bits - its 'pos' need 
+	 * not be the parent's 'pos'+'bits'!
+	 *
+	 * If it does match the current key, get pos/bits from it, extract 
+	 * the index from our key, push the T_TNODE and walk the tree.
+	 *
+	 * If it doesn't, we have to replace it with a new T_TNODE.
+	 *
+	 * If we point to a T_LEAF, it might or might not have the same key 
+	 * as we do. If it does, just change the value, update the T_LEAF's 
+	 * value, and return it. 
+	 * If it doesn't, we need to replace it with a T_TNODE.
+	 */
+
+	while (n != NULL &&  NODE_TYPE(n) == T_TNODE) {
+		tn = (struct tnode *) n;
+			
+		check_tnode(tn);
+		
+		if(tkey_sub_equals(tn->key, pos, tn->pos-pos, key)) {
+			tp = tn;
+			pos=tn->pos + tn->bits;
+			n = tnode_get_child(tn, tkey_extract_bits(key, tn->pos, tn->bits));
+
+			if(n && NODE_PARENT(n) != tn) {
+				printk("BUG tn=%p, n->parent=%p\n", tn, NODE_PARENT(n));
+				BUG();
+			}
+		}
+		else
+			break;
+	}
+
+	/*
+	 * n  ----> NULL, LEAF or TNODE
+	 *
+	 * tp is n's (parent) ----> NULL or TNODE  
+	 */
+
+	if(tp && IS_LEAF(tp))
+		BUG();
+
+	t->revision++;
+
+	/* Case 1: n is a leaf. Compare prefixes */
+
+	if (n != NULL && IS_LEAF(n) && tkey_equals(key, n->key)) { 
+		struct leaf *l = ( struct leaf *)  n;
+		
+		li = leaf_info_new(plen);
+		
+		if(! li) 
+			BUG();
+
+		fa_head = &li->falh;
+		insert_leaf_info(&l->list, li);
+		goto done;
+	}
+	t->size++;
+	l = leaf_new();
+
+	if(! l) 
+		BUG();
+
+	l->key = key;
+	li = leaf_info_new(plen);
+
+	if(! li) 
+		BUG();
+
+	fa_head = &li->falh;
+	insert_leaf_info(&l->list, li);
+
+	/* Case 2: n is NULL, and will just insert a new leaf */
+	if (t->trie && n == NULL) {
+
+		NODE_SET_PARENT(l, tp);
+		
+		if (!tp) 
+			BUG();
+
+		else {
+			cindex = tkey_extract_bits(key, tp->pos, tp->bits);
+			put_child(t, (struct tnode *)tp, cindex, (struct node *)l);
+		}
+	}
+	/* Case 3: n is a LEAF or a TNODE and the key doesn't match. */
+	else {
+		/* 
+		 *  Add a new tnode here 
+		 *  first tnode need some special handling
+		 */
+
+		if (tp)
+			pos=tp->pos+tp->bits;
+		else
+			pos=0;
+		if(n) {
+			newpos = tkey_mismatch(key, pos, n->key);
+			tn = tnode_new(n->key, newpos, 1);
+		}
+		else {
+			newpos = 0;
+			tn = tnode_new(key, newpos, 1); /* First tnode */ 
+		}
+		if(!tn) 
+			trie_bug("tnode_pfx_new failed");
+
+		NODE_SET_PARENT(tn, tp);
+
+		missbit=tkey_extract_bits(key, newpos, 1);
+		put_child(t, tn, missbit, (struct node *)l);
+		put_child(t, tn, 1-missbit, n);
+
+		if(tp) {
+			cindex = tkey_extract_bits(key, tp->pos, tp->bits);
+			put_child(t, (struct tnode *)tp, cindex, (struct node *)tn);
+		}
+		else { 
+			t->trie = (struct node*) tn; /* First tnode */
+			tp = tn;
+		}
+	}
+	if(tp && tp->pos+tp->bits > 32) {
+		printk("ERROR tp=%p pos=%d, bits=%d, key=%0x plen=%d\n", 
+		       tp, tp->pos, tp->bits, key, plen);
+	}
+	/* Rebalance the trie */
+	t->trie = trie_rebalance(t, tp);
+done:;
+	return fa_head;
+}
+
+static int
+fn_trie_insert(struct fib_table *tb, struct rtmsg *r, struct kern_rta *rta,
+	       struct nlmsghdr *nlhdr, struct netlink_skb_parms *req)
+{
+	struct trie *t = (struct trie *) tb->tb_data;
+	struct fib_alias *fa, *new_fa;
+	struct list_head *fa_head=NULL;
+	struct fib_info *fi;
+	int plen = r->rtm_dst_len;
+	int type = r->rtm_type;
+	u8 tos = r->rtm_tos;
+	u32 key, mask;
+	int err;
+	struct leaf *l;
+
+	if (plen > 32)
+		return -EINVAL;
+
+	key = 0;
+	if (rta->rta_dst) 
+		memcpy(&key, rta->rta_dst