Re: [PATCHv5 bpf-next 20/28] libbpf: Add support to create tracing multi link

[Jiri Olsa <olsajiri@gmail.com>]

On Sat, Apr 18, 2026 at 06:10:58AM +0000, bot+bpf-ci@kernel.org wrote:
> > diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
> > index 49368ee161b1..9bf7e8754c7b 100644
> > --- a/tools/lib/bpf/libbpf.c
> > +++ b/tools/lib/bpf/libbpf.c
> 
> [ ... ]
> 
> > @@ -12510,6 +12592,197 @@ bool btf_type_is_traceable_func(const struct btf *btf, const struct btf_type *t
> >  	return true;
> >  }
> >
> > +static int collect_func_ids_by_glob(const struct bpf_program *prog, const char *pattern, __u32 **ids)
> > +{
> > +	struct bpf_object *obj = prog->obj;
> > +	const struct module_btf *mod;
> > +	struct btf *btf = NULL;
> > +	const char *sep;
> > +	int err;
> > +
> > +	err = bpf_object__load_vmlinux_btf(obj, true);
> > +	if (err)
> > +		return err;
> > +
> > +	/* In case we have module specified, we will find its btf and use that. */
> > +	sep = strchr(pattern, ':');
> > +	if (sep) {
> > +		mod = find_attach_module(obj, pattern);
> > +		if (!mod) {
> > +			err = -EINVAL;
> > +			goto cleanup;
> > +		}
> > +		btf = mod->btf;
> > +		pattern = sep + 1;
> > +	} else {
> > +		/* Program is loaded for kernel module. */
> > +		if (prog->attach_btf_obj_fd)
> > +			return -EINVAL;
> > +		btf = obj->btf_vmlinux;
> > +	}
> > +
> > +	err = collect_btf_func_ids_by_glob(btf, pattern, ids);
> > +
> > +cleanup:
> > +	bpf_object_cleanup_btf(obj);
> > +	return err;
> > +}
> 
> Does this function leak the vmlinux BTF when prog->attach_btf_obj_fd is
> set? The early return bypasses the cleanup label that calls
> bpf_object_cleanup_btf(obj). Every other error path goes through
> cleanup, which suggests the BTF loaded by bpf_object__load_vmlinux_btf()
> needs to be cleaned up before returning.
> 
> The design pattern here is that bpf_object__load_vmlinux_btf(obj, true)
> is called specifically at attach-time (after the object has already been
> post-load-cleaned), so obj->btf_vmlinux is freshly loaded. Skipping the
> cleanup leaves that freshly-loaded btf_vmlinux attached to the bpf_object
> until bpf_object__close().
> 
> Should this be 'err = -EINVAL; goto cleanup;' to match the other error
> paths?

yea, should be 'goto cleanup', will fix

jirka