From: Hou Tao Date: Fri, 6 Dec 2024 11:06:14 +0000 (+0800) Subject: bpf: Remove unnecessary check when updating LPM trie X-Git-Tag: v6.13-rc2~11^2^2~8 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=156c977c539e87e173f505b23989d7b0ec0bc7d8;p=thirdparty%2Flinux.git 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: Toke Høiland-Jørgensen Acked-by: Daniel Borkmann Signed-off-by: Hou Tao Link: https://lore.kernel.org/r/20241206110622.1161752-2-houtao@huaweicloud.com Signed-off-by: Alexei Starovoitov --- diff --git a/kernel/bpf/lpm_trie.c b/kernel/bpf/lpm_trie.c index 9b60eda0f727b..73fd593d37451 100644 --- a/kernel/bpf/lpm_trie.c +++ b/kernel/bpf/lpm_trie.c @@ -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);