Commit eae6a075 authored by Hou Tao's avatar Hou Tao Committed by Alexei Starovoitov
Browse files

bpf: Handle BPF_EXIST and BPF_NOEXIST for LPM trie 



Add the currently missing handling for the BPF_EXIST and BPF_NOEXIST
flags. These flags can be specified by users and are relevant since LPM
trie supports exact matches during update.

Fixes: b95a5c4d ("bpf: add a longest prefix match trie map implementation")
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/20241206110622.1161752-4-houtao@huaweicloud.com


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent 3d5611b4

kernel/bpf/lpm_trie.c

+20 −3
Original line number Diff line number Diff line
@@ -375,6 +375,10 @@ static long trie_update_elem(struct bpf_map *map, 
	 * simply assign the @new_node to that slot and be done.

	 */

	if (!node) {

		if (flags == BPF_EXIST) {

			ret = -ENOENT;

			goto out;

		}

		rcu_assign_pointer(*slot, new_node);

		goto out;

	}
@@ -383,18 +387,31 @@ static long trie_update_elem(struct bpf_map *map, 
	 * which already has the correct data array set.

	 */

	if (node->prefixlen == matchlen) {

		if (!(node->flags & LPM_TREE_NODE_FLAG_IM)) {

			if (flags == BPF_NOEXIST) {

				ret = -EEXIST;

				goto out;

			}

			trie->n_entries--;

		} else if (flags == BPF_EXIST) {

			ret = -ENOENT;

			goto out;

		}



		new_node->child[0] = node->child[0];

		new_node->child[1] = node->child[1];



		if (!(node->flags & LPM_TREE_NODE_FLAG_IM))

			trie->n_entries--;



		rcu_assign_pointer(*slot, new_node);

		free_node = node;



		goto out;

	}



	if (flags == BPF_EXIST) {

		ret = -ENOENT;

		goto out;

	}



	/* If the new node matches the prefix completely, it must be inserted

	 * as an ancestor. Simply insert it between @node and *@slot.

	 */