From 939afb0657dd8c8f9486d172d6bb62fc902e2f23 Mon Sep 17 00:00:00 2001 From: Alexander Duyck Date: Wed, 31 Dec 2014 10:56:00 -0800 Subject: [PATCH] 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: Alexander Duyck Signed-off-by: David S. Miller --- net/ipv4/fib_trie.c | 36 +++++++++++++++++++++--------------- 1 file changed, 21 insertions(+), 15 deletions(-) diff --git a/net/ipv4/fib_trie.c b/net/ipv4/fib_trie.c index 3fe4dd917ce1..ac04f31a632e 100644 --- a/net/ipv4/fib_trie.c +++ b/net/ipv4/fib_trie.c @@ -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; - } - /* Case we have found a leaf. Compare prefixes */ - if (n != NULL && IS_LEAF(n) && tkey_equals(key, n->key)) - return n; + n = rcu_dereference_rtnl(n->child[index]); + } - return NULL; + return n; } static void trie_rebalance(struct trie *t, struct tnode *tn) -- 2.30.2