On Mon, Feb 21, 2022 at 11:34 PM Xu Kuohai <xukuohai@xxxxxxxxxx> wrote:
>
> If a FWD appears in the BTF before a STRUCT with the same name, the
> STRUCT is dumped with a conflicted name:
>
> $ bpftool btf dump file vmlinux format raw | grep "'unix_sock'"
> [81287] FWD 'unix_sock' fwd_kind=struct
> [89336] STRUCT 'unix_sock' size=1024 vlen=14
>
> $ bpftool btf dump file vmlinux format c | grep "struct unix_sock"
> struct unix_sock;
> struct unix_sock___2 { <--- conflict, the "___2" is unexpected
> struct unix_sock___2 *unix_sk;
>
> Fixes: 351131b51c7a ("libbpf: add btf_dump API for BTF-to-C conversion")
> Signed-off-by: Xu Kuohai <xukuohai@xxxxxxxxxx>
> ---
> tools/lib/bpf/btf_dump.c | 16 +++++++++-------
> 1 file changed, 9 insertions(+), 7 deletions(-)
>
> diff --git a/tools/lib/bpf/btf_dump.c b/tools/lib/bpf/btf_dump.c
> index 07ebe70d3a30..55079efbd8f1 100644
> --- a/tools/lib/bpf/btf_dump.c
> +++ b/tools/lib/bpf/btf_dump.c
> @@ -1505,13 +1505,15 @@ static const char *btf_dump_resolve_name(struct btf_dump *d, __u32 id,
> if (s->name_resolved)
> return *cached_name ? *cached_name : orig_name;
>
> - dup_cnt = btf_dump_name_dups(d, name_map, orig_name);
> - if (dup_cnt > 1) {
> - const size_t max_len = 256;
> - char new_name[max_len];
> -
> - snprintf(new_name, max_len, "%s___%zu", orig_name, dup_cnt);
> - *cached_name = strdup(new_name);
> + if (!btf_is_fwd(t)) {
let's handle FWD as a special case and not touch existing logic. Maybe
something like this?
if (btf_is_fwd(t) || (btf_is_enum(t) && btf_vlen(t) == 0)) {
s->name_resolved = 1;
return orig_name;
}
btf_is_enum() part should handle enum forward declarations (they are
represented as enums with no values defined)
> + dup_cnt = btf_dump_name_dups(d, name_map, orig_name);
> + if (dup_cnt > 1) {
> + const size_t max_len = 256;
> + char new_name[max_len];
> +
> + snprintf(new_name, max_len, "%s___%zu", orig_name, dup_cnt);
> + *cached_name = strdup(new_name);
> + }
> }
>
> s->name_resolved = 1;
> --
> 2.30.2
>
