Re: [PATCH 2/4] btf: use dt_btf_real_type_by_id() to resolve types

[Nick Alcock <nick.alcock@oracle.com>]

On 14 Apr 2026, Kris Van Hees said:

> Functions that need to check type data operate on the real type rather
> than a typedef or a type with modifiers.  Similarly, when a type of a
> function is needed, the prototype (BTF type BTF_KIND_PROTO) is what is
> really needed.
>
> Introducing dt_btf_real_type_by_id() removed duplication of code in other
> functions.

Perhaps dt_btf_resolve_type(), for consistency with the libctf function
naming?

Other than that...

> ---
>  libdtrace/dt_btf.c | 43 +++++++++++++++++++++++++++++--------------
>  1 file changed, 29 insertions(+), 14 deletions(-)
>
> diff --git a/libdtrace/dt_btf.c b/libdtrace/dt_btf.c
> index d08599192..56eb96a4e 100644
> --- a/libdtrace/dt_btf.c
> +++ b/libdtrace/dt_btf.c
> @@ -848,6 +848,26 @@ dt_btf_type_by_id(dtrace_hdl_t *dtp, const dt_btf_t *btf, int32_t id)
>  	return btf->types[id - (dtp->dt_shared_btf->type_cnt - 1)];
>  }
>  
> +static btf_type_t *
> +dt_btf_real_type_by_id(dtrace_hdl_t *dtp, const dt_btf_t *btf, int32_t id)
> +{
> +	btf_type_t	*type = dt_btf_type_by_id(dtp, btf, id);
> +
> +	do {
> +		switch (BTF_INFO_KIND(type->info)) {
> +		case BTF_KIND_CONST:
> +		case BTF_KIND_FUNC:
> +		case BTF_KIND_TYPEDEF:
> +		case BTF_KIND_VOLATILE:

Probably this should traverse BTF_KIND_RESTRICT as well. (The kernel
*does* use restrict qualifiers in some places. I was surprised too.)

-- 
NULL && (void)