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_struct_types() 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.
Changes in v3: 1. Patch 1: Adjusted the comment of btf_dedup_ref_type() to refer to typedef as well. 2. Patch 2: Update of the "dedup: recursive typedef" test to include a duplicated version of the types to make sure deduplication still happens in this case.
Changes in v2: 1. Patch 1: Refactored code to prevent copying existing logic. Instead of adding a new function we modify the existing btf_dedup_struct_type() function to handle the BTF_KIND_TYPEDEF case. Calls to btf_hash_struct() and btf_shallow_equal_struct() are replaced with calls to functions that select btf_hash_struct() / btf_hash_typedef() based on the type. 2. Patch 2: Added tests
v2: https://lore.kernel.org/lkml/cover.1762956564.git.paul.houssel@orange.com/
v1: https://lore.kernel.org/lkml/20251107153408.159342-1-paulhoussel2@gmail.com/
Paul Houssel (2): libbpf: fix BTF dedup to support recursive typedef definitions selftests/bpf: add BTF dedup tests for recursive typedef definitions
tools/lib/bpf/btf.c | 73 +++++++++++++++----- tools/testing/selftests/bpf/prog_tests/btf.c | 65 +++++++++++++++++ 2 files changed, 121 insertions(+), 17 deletions(-)