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bpf: Handle BPF_EXIST and BPF_NOEXIST for LPM trie

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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: b95a5c4db0 ("bpf: add a longest prefix match trie map implementation")
Reviewed-by: Toke Høiland-Jørgensen <toke@redhat.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20241206110622.1161752-4-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Hou Tao 2024-12-06 19:06:16 +08:00 • committed by Alexei Starovoitov
parent 3d5611b4d7
commit eae6a075e9
1 changed files with 20 additions and 3 deletions
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23
kernel/bpf/lpm_trie.c
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@ -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.
*/