On Wed, 2025-11-12 at 15:11 +0100, Paul Houssel wrote: > Handle recursive typedefs in BTF deduplication > > Pahole fails to encode BTF for some Go projects (e.g. Kubernetes and > Podman) due to recursive type definitions that create reference loops > not representable in C. These recursive typedefs trigger a failure in > the BTF deduplication algorithm. > > This patch extends btf_dedup_ref_type() to properly handle potential > recursion for BTF_KIND_TYPEDEF, similar to how recursion is already > handled for BTF_KIND_STRUCT. This allows pahole to successfully > generate BTF for Go binaries using recursive types without impacting > existing C-based workflows. > > Co-developed-by: Martin Horth <[email protected]> > Signed-off-by: Martin Horth <[email protected]> > Co-developed-by: Ouail Derghal <[email protected]> > Signed-off-by: Ouail Derghal <[email protected]> > Co-developed-by: Guilhem Jazeron <[email protected]> > Signed-off-by: Guilhem Jazeron <[email protected]> > Co-developed-by: Ludovic Paillat <[email protected]> > Signed-off-by: Ludovic Paillat <[email protected]> > Co-developed-by: Robin Theveniaut <[email protected]> > Signed-off-by: Robin Theveniaut <[email protected]> > Suggested-by: Tristan d'Audibert <[email protected]> > Signed-off-by: Paul Houssel <[email protected]> > > ---
No differences in BTF generated for kernel when using pahole built against libbpf with and without this patch. Acked-by: Eduard Zingerman <[email protected]> > @@ -4939,7 +4979,7 @@ static int btf_dedup_struct_types(struct btf_dedup *d) > /* > * Deduplicate reference type. > * > - * Once all primitive and struct/union types got deduplicated, we can easily > + * Once all primitive, struct/union and typedef types got deduplicated, we > can easily > * deduplicate all other (reference) BTF types. This is done in two steps: > * > * 1. Resolve all referenced type IDs into their canonical type IDs. This Nit: this passage continues as: * There is no danger of encountering cycles because in C type * system the only way to form type cycle is through struct/union, so any chain * of reference types, even those taking part in a type cycle, will inevitably * reach struct/union at some point. I think it needs adjustment to refer to typedef as well. [...]
