From 8a3f14bb1e944f496d1a16096435ddb2e12e4753 Mon Sep 17 00:00:00 2001 From: Sam James Date: Fri, 6 Sep 2024 14:48:14 +0100 Subject: [PATCH] libbpf: Workaround (another) -Wmaybe-uninitialized false positive MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit We get this with GCC 15 -O3 (at least): ``` libbpf.c: In function ‘bpf_map__init_kern_struct_ops’: libbpf.c:1109:18: error: ‘mod_btf’ may be used uninitialized [-Werror=maybe-uninitialized] 1109 | kern_btf = mod_btf ? mod_btf->btf : obj->btf_vmlinux; | ~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ libbpf.c:1094:28: note: ‘mod_btf’ was declared here 1094 | struct module_btf *mod_btf; | ^~~~~~~ In function ‘find_struct_ops_kern_types’, inlined from ‘bpf_map__init_kern_struct_ops’ at libbpf.c:1102:8: libbpf.c:982:21: error: ‘btf’ may be used uninitialized [-Werror=maybe-uninitialized] 982 | kern_type = btf__type_by_id(btf, kern_type_id); | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ libbpf.c: In function ‘bpf_map__init_kern_struct_ops’: libbpf.c:967:21: note: ‘btf’ was declared here 967 | struct btf *btf; | ^~~ ``` This is similar to the other libbpf fix from a few weeks ago for the same modelling-errno issue (fab45b962749184e1a1a57c7c583782b78fad539). Signed-off-by: Sam James Signed-off-by: Andrii Nakryiko Link: https://bugs.gentoo.org/939106 Link: https://lore.kernel.org/bpf/f6962729197ae7cdf4f6d1512625bd92f2322d31.1725630494.git.sam@gentoo.org --- tools/lib/bpf/libbpf.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index 27ad3c6ee868..4f29e06c2641 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -986,7 +986,7 @@ find_struct_ops_kern_types(struct bpf_object *obj, const char *tname_raw, { const struct btf_type *kern_type, *kern_vtype; const struct btf_member *kern_data_member; - struct btf *btf; + struct btf *btf = NULL; __s32 kern_vtype_id, kern_type_id; char tname[256]; __u32 i; @@ -1116,7 +1116,7 @@ static int bpf_map__init_kern_struct_ops(struct bpf_map *map) const struct btf *btf = obj->btf; struct bpf_struct_ops *st_ops; const struct btf *kern_btf; - struct module_btf *mod_btf; + struct module_btf *mod_btf = NULL; void *data, *kern_data; const char *tname; int err;