libbpf: handle BTF parsing and loading properly

This patch splits and cleans up error handling logic for loading BTF data.
Previously, if BTF data was parsed successfully, but failed to load into
kernel, we'd report nonsensical error code, instead of error returned from
btf__load(). Now btf__new() and btf__load() are handled separately with proper
cleanup and warning reporting.

Fixes: d29d87f7e612 ("btf: separate btf creation and loading")
Reported-by: Martin KaFai Lau <[email protected]>
Signed-off-by: Andrii Nakryiko <[email protected]>
Acked-by: Martin KaFai Lau <[email protected]>
Acked-by: Yonghong Song <[email protected]>
Signed-off-by: Daniel Borkmann <[email protected]>

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index d5b830d606010ad33fd780a514e3684f07d92506..5e977d2688da792684bca5d7e16a69e6cf375558 100644 (file)
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -835,12 +835,19 @@ static int bpf_object__elf_collect(struct bpf_object *obj, int flags)
                        obj->efile.maps_shndx = idx;
                else if (strcmp(name, BTF_ELF_SEC) == 0) {
                        obj->btf = btf__new(data->d_buf, data->d_size);
-                       if (IS_ERR(obj->btf) || btf__load(obj->btf)) {
+                       if (IS_ERR(obj->btf)) {
                                pr_warning("Error loading ELF section %s: %ld. Ignored and continue.\n",
                                           BTF_ELF_SEC, PTR_ERR(obj->btf));
-                               if (!IS_ERR(obj->btf))
-                                       btf__free(obj->btf);
                                obj->btf = NULL;
+                               continue;
+                       }
+                       err = btf__load(obj->btf);
+                       if (err) {
+                               pr_warning("Error loading %s into kernel: %d. Ignored and continue.\n",
+                                          BTF_ELF_SEC, err);
+                               btf__free(obj->btf);
+                               obj->btf = NULL;
+                               err = 0;
                        }
                } else if (strcmp(name, BTF_EXT_ELF_SEC) == 0) {
                        btf_ext_data = data;