From ecf998ed8ff51efd3887ff7caca0a0cc56a88082 Mon Sep 17 00:00:00 2001
From: Eric Long <i@hack3r.moe>
Date: Wed, 2 Oct 2024 14:25:06 +0800
Subject: [PATCH] libbpf: Do not resolve size on duplicate FUNCs

FUNCs do not have sizes, thus currently btf__resolve_size will fail
with -EINVAL. Add conditions so that we only update size when the BTF
object is not function or function prototype.

Signed-off-by: Eric Long <i@hack3r.moe>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20241002-libbpf-dup-extern-funcs-v4-1-560eb460ff90@hack3r.moe
---
 src/linker.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/linker.c b/src/linker.c
index 81dbbdd79..f83c1c299 100644
--- a/src/linker.c
+++ b/src/linker.c
@@ -2451,6 +2451,10 @@ static int linker_append_btf(struct bpf_linker *linker, struct src_obj *obj)
 			if (glob_sym && glob_sym->var_idx >= 0) {
 				__s64 sz;
 
+				/* FUNCs don't have size, nothing to update */
+				if (btf_is_func(t))
+					continue;
+
 				dst_var = &dst_sec->sec_vars[glob_sym->var_idx];
 				/* Because underlying BTF type might have
 				 * changed, so might its size have changed, so