On Fri, Oct 22, 2021 at 10:16 AM Quentin Monnet <quentin@xxxxxxxxxxxxx> wrote:
>
> In order to show BPF programs and maps using BTF objects when the latter
> are being listed, bpftool creates hash maps to store all relevant items.
> This commit is part of a set that transitions from the kernel's hash map
> implementation to the one coming with libbpf.
>
> The motivation is to make bpftool less dependent of kernel headers, to
> ease the path to a potential out-of-tree mirror, like libbpf has.
>
> This commit focuses on the two hash maps used by bpftool when listing
> BTF objects to store references to programs and maps, and convert them
> to the libbpf's implementation.
>
> Signed-off-by: Quentin Monnet <quentin@xxxxxxxxxxxxx>
> ---
> tools/bpf/bpftool/btf.c | 126 ++++++++++++++++-----------------------
> tools/bpf/bpftool/main.h | 5 ++
> 2 files changed, 57 insertions(+), 74 deletions(-)
>
[...]
> @@ -741,28 +724,20 @@ build_btf_type_table(struct btf_attach_table *tab, enum bpf_obj_type type,
> if (!btf_id)
> continue;
>
> - obj_node = calloc(1, sizeof(*obj_node));
> - if (!obj_node) {
> - p_err("failed to allocate memory: %s", strerror(errno));
> - err = -ENOMEM;
> - goto err_free;
> - }
> -
> - obj_node->obj_id = id;
> - obj_node->btf_id = btf_id;
> - hash_add(tab->table, &obj_node->hash, obj_node->btf_id);
> + hashmap__append(tab, u32_as_hash_field(btf_id),
> + u32_as_hash_field(id));
error handling is missing
> }
>
> return 0;
>
> err_free:
> - delete_btf_table(tab);
> + hashmap__free(tab);
> return err;
> }
>
> static int
> -build_btf_tables(struct btf_attach_table *btf_prog_table,
> - struct btf_attach_table *btf_map_table)
> +build_btf_tables(struct hashmap *btf_prog_table,
> + struct hashmap *btf_map_table)
> {
> struct bpf_prog_info prog_info;
> __u32 prog_len = sizeof(prog_info);
> @@ -778,7 +753,7 @@ build_btf_tables(struct btf_attach_table *btf_prog_table,
> err = build_btf_type_table(btf_map_table, BPF_OBJ_MAP, &map_info,
> &map_len);
> if (err) {
> - delete_btf_table(btf_prog_table);
> + hashmap__free(btf_prog_table);
> return err;
> }
>
> @@ -787,10 +762,10 @@ build_btf_tables(struct btf_attach_table *btf_prog_table,
>
> static void
> show_btf_plain(struct bpf_btf_info *info, int fd,
> - struct btf_attach_table *btf_prog_table,
> - struct btf_attach_table *btf_map_table)
> + struct hashmap *btf_prog_table,
> + struct hashmap *btf_map_table)
> {
> - struct btf_attach_point *obj;
> + struct hashmap_entry *entry;
> const char *name = u64_to_ptr(info->name);
> int n;
>
> @@ -804,18 +779,17 @@ show_btf_plain(struct bpf_btf_info *info, int fd,
> printf("size %uB", info->btf_size);
>
> n = 0;
> - hash_for_each_possible(btf_prog_table->table, obj, hash, info->id) {
> - if (obj->btf_id == info->id)
> - printf("%s%u", n++ == 0 ? " prog_ids " : ",",
> - obj->obj_id);
> - }
> + hashmap__for_each_key_entry(btf_prog_table, entry,
> + u32_as_hash_field(info->id))
> + printf("%s%u", n++ == 0 ? " prog_ids " : ",",
> + hash_field_as_u32(entry->value));
nit: I'd add {}, it's getting a bit hard to follow
>
> n = 0;
> - hash_for_each_possible(btf_map_table->table, obj, hash, info->id) {
> - if (obj->btf_id == info->id)
> - printf("%s%u", n++ == 0 ? " map_ids " : ",",
> - obj->obj_id);
> - }
> + hashmap__for_each_key_entry(btf_map_table, entry,
> + u32_as_hash_field(info->id))
> + printf("%s%u", n++ == 0 ? " map_ids " : ",",
> + hash_field_as_u32(entry->value));
> +
> emit_obj_refs_plain(&refs_table, info->id, "\n\tpids ");
>
> printf("\n");
[...]
