From: Eric Dumazet <edumazet@google.com>
Date: Tue, 7 Aug 2012 10:45:47 +0000 (+0000)
Subject: fib: use __fls() on non null argument
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=79cda75a107da0d49732b5cb642b456264dd7e0e;p=linux-beck.git

fib: use __fls() on non null argument

__fls(x) is a bit faster than fls(x), granted we know x is non null.

As Ben Hutchings pointed out, fls(x) = __fls(x) + 1

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---

diff --git a/net/ipv4/fib_trie.c b/net/ipv4/fib_trie.c
index f0cdb30921c0..f84a0e90d675 100644
--- a/net/ipv4/fib_trie.c
+++ b/net/ipv4/fib_trie.c
@@ -1550,7 +1550,8 @@ int fib_table_lookup(struct fib_table *tb, const struct flowi4 *flp,
 		 * state.directly.
 		 */
 		if (pref_mismatch) {
-			int mp = KEYLENGTH - fls(pref_mismatch);
+			/* fls(x) = __fls(x) + 1 */
+			int mp = KEYLENGTH - __fls(pref_mismatch) - 1;
 
 			if (tkey_extract_bits(cn->key, mp, cn->pos - mp) != 0)
 				goto backtrace;