Currently, if `bpftool gen object` tries to link two objects that contains the same extern function prototype, libbpf will try to get their (non-existent) size by calling bpf__resolve_size like extern variables and fail with: libbpf: global 'whatever': failed to resolve size of underlying type: -22 This should not be the case, and this series adds conditions to update size only when the BTF kind is not function. Fixes: a46349227cd8 ("libbpf: Add linker extern resolution support for functions and global variables") Signed-off-by: Eric Long <i@xxxxxxxxxx> --- Changes in v4: - Remove redundant FUNC_PROTO check. - Merge tests into linked_funcs. - Link to v3: https://lore.kernel.org/r/20241001-libbpf-dup-extern-funcs-v3-0-42f7774efbf3@xxxxxxxxxx Changes in v3: - Simplifiy changes and shorten subjects, according to reviews. - Remove unused includes in selftests. - Link to v2: https://lore.kernel.org/r/20240929-libbpf-dup-extern-funcs-v2-0-0cc81de3f79f@xxxxxxxxxx Changes in v2: - Fix compile errors. Oops! - Link to v1: https://lore.kernel.org/r/20240929-libbpf-dup-extern-funcs-v1-0-df15fbd6525b@xxxxxxxxxx --- Eric Long (2): libbpf: do not resolve size on duplicate FUNCs selftests/bpf: test linking with duplicate extern functions tools/lib/bpf/linker.c | 4 ++++ tools/testing/selftests/bpf/progs/linked_funcs1.c | 8 ++++++++ tools/testing/selftests/bpf/progs/linked_funcs2.c | 8 ++++++++ 3 files changed, 20 insertions(+) --- base-commit: 93eeaab4563cc7fc0309bc1c4d301139762bbd60 change-id: 20240929-libbpf-dup-extern-funcs-871f4bad2122 Best regards, -- Eric Long <i@xxxxxxxxxx>