[PATCH net-next] net: ipv4: optimize tkey_mismatch

[igorm@etf.rs]

From: Igor Maravic <igorm@etf.rs>

Optimize tkey_mismatch function by using __fls function.

Signed-off-by: Igor Maravic <igorm@etf.rs>
---
 net/ipv4/fib_trie.c |   10 ++--------
 1 file changed, 2 insertions(+), 8 deletions(-)

diff --git a/net/ipv4/fib_trie.c b/net/ipv4/fib_trie.c
index ec45621..b4b126c 100644
--- a/net/ipv4/fib_trie.c
+++ b/net/ipv4/fib_trie.c
@@ -265,14 +265,8 @@ static inline int tkey_sub_equals(t_key a, int offset, int bits, t_key b)
 
 static inline int tkey_mismatch(t_key a, int offset, t_key b)
 {
-	t_key diff = a ^ b;
-	int i = offset;
-
-	if (!diff)
-		return 0;
-	while ((diff << i) >> (KEYLENGTH-1) == 0)
-		i++;
-	return i;
+	t_key diff = (a ^ b) & (~((t_key)0) << offset >> offset);
+	return diff ? (KEYLENGTH - __fls(diff) - 1) : 0;
 }
 
 /*
-- 
1.7.9.5