Re: [RFC PATCH v1 10/10] selftests/bpf: add file dynptr tests

[Eduard Zingerman <eddyz87@gmail.com>]

On Fri, 2025-10-03 at 17:04 +0100, Mykyta Yatsenko wrote:

[...]

> diff --git a/tools/testing/selftests/bpf/progs/file_reader.c b/tools/testing/selftests/bpf/progs/file_reader.c
> new file mode 100644
> index 000000000000..9dd9a68f3563
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/progs/file_reader.c

Do we really need an example of ELF parsing in selftests?
Maybe just stick to smaller test cases, exercising specific behaviors?

[...]

> diff --git a/tools/testing/selftests/bpf/progs/file_reader_fail.c b/tools/testing/selftests/bpf/progs/file_reader_fail.c
> new file mode 100644
> index 000000000000..449c4f9a1c74
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/progs/file_reader_fail.c

[...]

> +static long process_vma_unreleased_ref(struct task_struct *task, struct vm_area_struct *vma,
> +				       void *data)
> +{
> +	struct bpf_dynptr dynptr;
> +
> +	if (!vma->vm_file)
> +		return 1;
> +
> +	err = bpf_dynptr_from_file(vma->vm_file, 0, &dynptr);
> +	return err ? 1 : 0;
> +}
> +
> +SEC("fentry.s/" SYS_PREFIX "sys_nanosleep")
> +__failure __msg("Unreleased reference id=") int on_nanosleep_unreleased_ref(void *ctx)
> +{
> +	struct task_struct *task = bpf_get_current_task_btf();
> +
> +	bpf_find_vma(task, (unsigned long)user_ptr, process_vma_unreleased_ref, NULL, 0);

Why testing this via callback?

> +	return 0;
> +}

[...]