Commit 939afb06 authored by Alexander Duyck's avatar Alexander Duyck Committed by David S. Miller
Browse files

fib_trie: Optimize fib_find_node 



This patch makes use of the same features I made use of for
fib_table_lookup to streamline fib_find_node.  The resultant code should be
smaller and run faster than the original.

Signed-off-by: default avatarAlexander Duyck <alexander.h.duyck@redhat.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 9f9e636d

net/ipv4/fib_trie.c

+21 −15
Original line number Diff line number Diff line
@@ -892,28 +892,34 @@ static void insert_leaf_info(struct hlist_head *head, struct leaf_info *new) 
}



/* rcu_read_lock needs to be hold by caller from readside */



static struct tnode *fib_find_node(struct trie *t, u32 key)

{

	struct tnode *n = rcu_dereference_rtnl(t->trie);

	int pos = 0;



	while (n && IS_TNODE(n)) {

		if (tkey_sub_equals(n->key, pos, n->pos-pos, key)) {

			pos = n->pos + n->bits;

			n = tnode_get_child_rcu(n,

						tkey_extract_bits(key,

								  n->pos,

								  n->bits));

		} else

	while (n) {

		unsigned long index = get_index(key, n);



		/* This bit of code is a bit tricky but it combines multiple

		 * checks into a single check.  The prefix consists of the

		 * prefix plus zeros for the bits in the cindex. The index

		 * is the difference between the key and this value.  From

		 * this we can actually derive several pieces of data.

		 *   if !(index >> bits)

		 *     we know the value is cindex

		 *   else

		 *     we have a mismatch in skip bits and failed

		 */

		if (index >> n->bits)

			return NULL;



		/* we have found a leaf. Prefixes have already been compared */

		if (IS_LEAF(n))

			break;



		n = rcu_dereference_rtnl(n->child[index]);

	}

	/* Case we have found a leaf. Compare prefixes */



	if (n != NULL && IS_LEAF(n) && tkey_equals(key, n->key))

	return n;



	return NULL;

}



static void trie_rebalance(struct trie *t, struct tnode *tn)