Re: [PATCH bpf-next v4 04/16] selftests/bpf: Clone a program that calls a module kfunc

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Low] selftests/bpf: new standalone file for narrow bpf_program__clone() variant
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commit 037d01e59174031ad79e435ca7e39a5bb4ce575d
Author: Kumar Kartikeya Dwivedi <memxor@gmail.com>

selftests/bpf: Clone a program that calls a module kfunc

This commit adds a selftest that opens kfunc_call_test, prepares the object
via bpf_object__prepare(), and loads kfunc_call_test1 using
bpf_program__clone() to verify module BTF fd handling in the object's
fd_array.

> diff --git a/tools/testing/selftests/bpf/prog_tests/clone_module_kfunc.c b/tools/testing/selftests/bpf/prog_tests/clone_module_kfunc.c
> new file mode 100644
> index 0000000000000..fa6ccbaa7fd98
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/prog_tests/clone_module_kfunc.c
> @@ -0,0 +1,30 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/* Copyright (c) 2026 Meta Platforms, Inc. and affiliates. */
> +#include <test_progs.h>
> +#include "kfunc_call_test.skel.h"
> +
> +/*
> + * bpf_program__clone() loads a program from a prepared object with the
> + * fd_array of the object, where module BTF fds start at slot 1 and slot 0 is
> + * empty. It used to pass the fill index of that array as fd_array_cnt, which
> + * made the kernel resolve slot 0 and fail the load.
> + */
> +void test_clone_module_kfunc(void)
> +{
> +	struct kfunc_call_test *skel;
> +	int err, fd;
> +
> +	skel = kfunc_call_test__open();
> +	if (!ASSERT_OK_PTR(skel, "skel_open"))
> +		return;
> +
> +	err = bpf_object__prepare(skel->obj);
> +	if (!ASSERT_OK(err, "prepare"))
> +		goto out;
> +
> +	fd = bpf_program__clone(skel->progs.kfunc_call_test1, NULL);
> +	if (ASSERT_GE(fd, 0, "clone"))
> +		close(fd);
> +out:
> +	kfunc_call_test__destroy(skel);
> +}

[Severity: Low]
This isn't a bug, but test_clone_module_kfunc() in
tools/testing/selftests/bpf/prog_tests/clone_module_kfunc.c adds a new
standalone test file for a single bpf_object__prepare() and
bpf_program__clone() check on kfunc_call_test.skel.h.

In the same directory, tools/testing/selftests/bpf/prog_tests/kfunc_call.c
already includes kfunc_call_test.skel.h, exercises kfunc_call_test1 across
loader variants, and groups subtests under test_kfunc_call():

tools/testing/selftests/bpf/prog_tests/kfunc_call.c:test_kfunc_call() {
	test_main();

	if (test__start_subtest("subprog"))
		test_subprog();

	if (test__start_subtest("subprog_lskel"))
		test_subprog_lskel();

	if (test__start_subtest("destructive"))
		test_destructive();
}

Similarly, tools/testing/selftests/bpf/prog_tests/prepare.c and
tools/testing/selftests/bpf/prog_tests/clone_attach_btf_id.c already test
bpf_object__prepare() and bpf_program__clone().

Could this check be added as a subtest or case in an existing test file such
as kfunc_call.c, prepare.c, or clone_attach_btf_id.c (similar to how the
preceding patch in the series extended prog_tests/map_excl.c) instead of
adding a new standalone file?

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20261019032401.2302823-1-memxor@gmail.com?part=4