bpf: lpm_trie memory usage

trie_mem_usage() is introduced to calculate the lpm_trie memory usage.
Some small memory allocations are ignored. The inner node is also
ignored.

The result as follows,

- before
10: lpm_trie  flags 0x1
        key 8B  value 8B  max_entries 65536  memlock 1048576B

- after
10: lpm_trie  flags 0x1
        key 8B  value 8B  max_entries 65536  memlock 2291536B

Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Link: https://lore.kernel.org/r/20230305124615.12358-3-laoar.shao@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

diff --git a/kernel/bpf/lpm_trie.c b/kernel/bpf/lpm_trie.c
index d833496e9e42633fb159a044d12ce41f1521fa8d..dc23f2ac9cde15852ee3e35899cb62973e75034b 100644 (file)
--- a/kernel/bpf/lpm_trie.c
+++ b/kernel/bpf/lpm_trie.c
@@ -720,6 +720,16 @@ static int trie_check_btf(const struct bpf_map *map,
               -EINVAL : 0;
 }
 
+static u64 trie_mem_usage(const struct bpf_map *map)
+{
+       struct lpm_trie *trie = container_of(map, struct lpm_trie, map);
+       u64 elem_size;
+
+       elem_size = sizeof(struct lpm_trie_node) + trie->data_size +
+                           trie->map.value_size;
+       return elem_size * READ_ONCE(trie->n_entries);
+}
+
 BTF_ID_LIST_SINGLE(trie_map_btf_ids, struct, lpm_trie)
 const struct bpf_map_ops trie_map_ops = {
        .map_meta_equal = bpf_map_meta_equal,
@@ -733,5 +743,6 @@ const struct bpf_map_ops trie_map_ops = {
        .map_update_batch = generic_map_update_batch,
        .map_delete_batch = generic_map_delete_batch,
        .map_check_btf = trie_check_btf,
+       .map_mem_usage = trie_mem_usage,
        .map_btf_id = &trie_map_btf_ids[0],
 };