Commit 156c977c authored by Hou Tao's avatar Hou Tao Committed by Alexei Starovoitov
Browse files

bpf: Remove unnecessary check when updating LPM trie 



When "node->prefixlen == matchlen" is true, it means that the node is
fully matched. If "node->prefixlen == key->prefixlen" is false, it means
the prefix length of key is greater than the prefix length of node,
otherwise, matchlen will not be equal with node->prefixlen. However, it
also implies that the prefix length of node must be less than
max_prefixlen.

Therefore, "node->prefixlen == trie->max_prefixlen" will always be false
when the check of "node->prefixlen == key->prefixlen" returns false.
Remove this unnecessary comparison.

Reviewed-by: default avatarToke Høiland-Jørgensen <toke@redhat.com>
Acked-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Signed-off-by: default avatarHou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20241206110622.1161752-2-houtao@huaweicloud.com


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent e2cf9133

kernel/bpf/lpm_trie.c

+1 −2
Original line number Diff line number Diff line
@@ -364,8 +364,7 @@ static long trie_update_elem(struct bpf_map *map, 
		matchlen = longest_prefix_match(trie, node, key);



		if (node->prefixlen != matchlen ||

		    node->prefixlen == key->prefixlen ||

		    node->prefixlen == trie->max_prefixlen)

		    node->prefixlen == key->prefixlen)

			break;



		next_bit = extract_bit(key->data, node->prefixlen);