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| author | Eric Dumazet <eric.dumazet@gmail.com> | 2010-10-13 06:56:11 +0000 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2010-10-16 11:13:22 -0700 |
| commit | 874ffa8f72444d6253d2669fed304875c128f86b (patch) | |
| tree | 1b00dc1984fa2984020c06fbc1e48b8c00366f02 /net/ipv4/fib_trie.c | |
| parent | a0a4a85a15df6335e3d11f83b2ac06ebebea313f (diff) | |
| download | lwn-874ffa8f72444d6253d2669fed304875c128f86b.tar.gz lwn-874ffa8f72444d6253d2669fed304875c128f86b.zip | |
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 <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4/fib_trie.c')
| -rw-r--r-- | net/ipv4/fib_trie.c | 16 |
1 files changed, 4 insertions, 12 deletions
diff --git a/net/ipv4/fib_trie.c b/net/ipv4/fib_trie.c index 271c89bdf049..31494f335686 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) |