From 874ffa8f72444d6253d2669fed304875c128f86b Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Wed, 13 Oct 2010 06:56:11 +0000 Subject: [PATCH] fib_trie: use fls() instead of open coded loop fib_table_lookup() might use fls() to speedup an open coded loop. Noticed while doing a profile analysis. Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller --- net/ipv4/fib_trie.c | 16 ++++------------ 1 file changed, 4 insertions(+), 12 deletions(-) diff --git a/net/ipv4/fib_trie.c b/net/ipv4/fib_trie.c index 271c89bdf04..31494f33568 100644 --- a/net/ipv4/fib_trie.c +++ b/net/ipv4/fib_trie.c @@ -1384,8 +1384,7 @@ int fib_table_lookup(struct fib_table *tb, const struct flowi *flp, t_key cindex = 0; int current_prefix_length = KEYLENGTH; struct tnode *cn; - t_key node_prefix, key_prefix, pref_mismatch; - int mp; + t_key pref_mismatch; rcu_read_lock(); @@ -1500,10 +1499,7 @@ int fib_table_lookup(struct fib_table *tb, const struct flowi *flp, * matching prefix. */ - node_prefix = mask_pfx(cn->key, cn->pos); - key_prefix = mask_pfx(key, cn->pos); - pref_mismatch = key_prefix^node_prefix; - mp = 0; + pref_mismatch = mask_pfx(cn->key ^ key, cn->pos); /* * In short: If skipped bits in this node do not match @@ -1511,13 +1507,9 @@ int fib_table_lookup(struct fib_table *tb, const struct flowi *flp, * state.directly. */ if (pref_mismatch) { - while (!(pref_mismatch & (1<<(KEYLENGTH-1)))) { - mp++; - pref_mismatch = pref_mismatch << 1; - } - key_prefix = tkey_extract_bits(cn->key, mp, cn->pos-mp); + int mp = KEYLENGTH - fls(pref_mismatch); - if (key_prefix != 0) + if (tkey_extract_bits(cn->key, mp, cn->pos - mp) != 0) goto backtrace; if (current_prefix_length >= cn->pos) -- 2.11.4.GIT