[PATCH] resolve_btfids: Refactor the sort_btf_by_name function

[PATCH] resolve_btfids: Refactor the sort_btf_by_name function

[Donglin Peng]

From: Donglin Peng <pengdonglin@xiaomi.com>

Preserve original relative order of anonymous or same-named
types to improve the consistency.

No functional changes.

Cc: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Donglin Peng <pengdonglin@xiaomi.com>
---
 tools/bpf/resolve_btfids/main.c | 18 +++++++++++-------
 1 file changed, 11 insertions(+), 7 deletions(-)

diff --git a/tools/bpf/resolve_btfids/main.c b/tools/bpf/resolve_btfids/main.c
index db8d1554bdcc..ca7fcd03efb6 100644
--- a/tools/bpf/resolve_btfids/main.c
+++ b/tools/bpf/resolve_btfids/main.c
@@ -1226,22 +1226,26 @@ static int cmp_type_names(const void *a, const void *b, void *priv)
 	const struct btf_type *ta = btf__type_by_id(btf, *(__u32 *)a);
 	const struct btf_type *tb = btf__type_by_id(btf, *(__u32 *)b);
 	const char *na, *nb;
+	int r;
 
 	na = btf__str_by_offset(btf, ta->name_off);
 	nb = btf__str_by_offset(btf, tb->name_off);
-	return strcmp(na, nb);
+	r = strcmp(na, nb);
+	if (r != 0)
+		return r;
+
+	/* preserve original relative order of anonymous or same-named types */
+	return *(__u32 *)a < *(__u32 *)b ? -1 : 1;
 }
 
 static int sort_btf_by_name(struct btf *btf)
 {
 	__u32 *permute_ids = NULL, *id_map = NULL;
 	int nr_types, i, err = 0;
-	__u32 start_id = 0, start_offs = 1, id;
+	__u32 start_id = 0, id;
 
-	if (btf__base_btf(btf)) {
+	if (btf__base_btf(btf))
 		start_id = btf__type_cnt(btf__base_btf(btf));
-		start_offs = 0;
-	}
 	nr_types = btf__type_cnt(btf) - start_id;
 
 	permute_ids = calloc(nr_types, sizeof(*permute_ids));
@@ -1259,8 +1263,8 @@ static int sort_btf_by_name(struct btf *btf)
 	for (i = 0, id = start_id; i < nr_types; i++, id++)
 		permute_ids[i] = id;
 
-	qsort_r(permute_ids + start_offs, nr_types - start_offs,
-		sizeof(*permute_ids), cmp_type_names, btf);
+	qsort_r(permute_ids, nr_types, sizeof(*permute_ids), cmp_type_names,
+		btf);
 
 	for (i = 0; i < nr_types; i++) {
 		id = permute_ids[i] - start_id;
-- 
2.34.1

Re: [PATCH] resolve_btfids: Refactor the sort_btf_by_name function

[Andrii Nakryiko]

On Mon, Feb 2, 2026 at 4:01 AM Donglin Peng <dolinux.peng@gmail.com> wrote:
>
> From: Donglin Peng <pengdonglin@xiaomi.com>
>
> Preserve original relative order of anonymous or same-named
> types to improve the consistency.
>
> No functional changes.
>
> Cc: Andrii Nakryiko <andrii@kernel.org>
> Signed-off-by: Donglin Peng <pengdonglin@xiaomi.com>
> ---
>  tools/bpf/resolve_btfids/main.c | 18 +++++++++++-------
>  1 file changed, 11 insertions(+), 7 deletions(-)
>

patchbot didn't notice this, but I've applied this to bpf-next, thanks

> diff --git a/tools/bpf/resolve_btfids/main.c b/tools/bpf/resolve_btfids/main.c
> index db8d1554bdcc..ca7fcd03efb6 100644
> --- a/tools/bpf/resolve_btfids/main.c
> +++ b/tools/bpf/resolve_btfids/main.c
> @@ -1226,22 +1226,26 @@ static int cmp_type_names(const void *a, const void *b, void *priv)
>         const struct btf_type *ta = btf__type_by_id(btf, *(__u32 *)a);
>         const struct btf_type *tb = btf__type_by_id(btf, *(__u32 *)b);
>         const char *na, *nb;
> +       int r;
>
>         na = btf__str_by_offset(btf, ta->name_off);
>         nb = btf__str_by_offset(btf, tb->name_off);
> -       return strcmp(na, nb);
> +       r = strcmp(na, nb);
> +       if (r != 0)
> +               return r;
> +
> +       /* preserve original relative order of anonymous or same-named types */
> +       return *(__u32 *)a < *(__u32 *)b ? -1 : 1;
>  }
>
>  static int sort_btf_by_name(struct btf *btf)
>  {
>         __u32 *permute_ids = NULL, *id_map = NULL;
>         int nr_types, i, err = 0;
> -       __u32 start_id = 0, start_offs = 1, id;
> +       __u32 start_id = 0, id;
>
> -       if (btf__base_btf(btf)) {
> +       if (btf__base_btf(btf))
>                 start_id = btf__type_cnt(btf__base_btf(btf));
> -               start_offs = 0;
> -       }
>         nr_types = btf__type_cnt(btf) - start_id;
>
>         permute_ids = calloc(nr_types, sizeof(*permute_ids));
> @@ -1259,8 +1263,8 @@ static int sort_btf_by_name(struct btf *btf)
>         for (i = 0, id = start_id; i < nr_types; i++, id++)
>                 permute_ids[i] = id;
>
> -       qsort_r(permute_ids + start_offs, nr_types - start_offs,
> -               sizeof(*permute_ids), cmp_type_names, btf);
> +       qsort_r(permute_ids, nr_types, sizeof(*permute_ids), cmp_type_names,
> +               btf);
>
>         for (i = 0; i < nr_types; i++) {
>                 id = permute_ids[i] - start_id;
> --
> 2.34.1
>