Commit 874ffa8f authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

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: default avatarEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent a0a4a85a

net/ipv4/fib_trie.c

+4 −12
Original line number Diff line number Diff line
@@ -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)