Re: [PATCH bpf-next v1 5/8] selftests/bpf: Add test for io_uring BPF iterators

[Yonghong Song <yhs@fb.com>]

On 11/18/21 10:33 AM, Kumar Kartikeya Dwivedi wrote:
> On Thu, Nov 18, 2021 at 11:24:19PM IST, Yonghong Song wrote:
>>
>>
>> On 11/15/21 9:42 PM, Kumar Kartikeya Dwivedi wrote:
>>> This exercises the io_uring_buf and io_uring_file iterators, and tests
>>> sparse file sets as well.
>>>
>>> Cc: Jens Axboe <axboe@kernel.dk>
>>> Cc: Pavel Begunkov <asml.silence@gmail.com>
>>> Cc: io-uring@vger.kernel.org
>>> Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
>>> ---
>>>    .../selftests/bpf/prog_tests/bpf_iter.c       | 226 ++++++++++++++++++
>>>    .../selftests/bpf/progs/bpf_iter_io_uring.c   |  50 ++++
>>>    2 files changed, 276 insertions(+)
>>>    create mode 100644 tools/testing/selftests/bpf/progs/bpf_iter_io_uring.c
>>>
[...]
>>> +
>>> +	ret = snprintf(str, sizeof(buf) - len, "E:%zu\n", ARRAY_SIZE(iovs));
>>> +	if (!ASSERT_GE(ret, 0, "snprintf") || !ASSERT_LT(ret, sizeof(buf) - len, "snprintf"))
>>> +		goto end_close_fd;
>>> +
>>> +	iter_fd = bpf_iter_create(bpf_link__fd(skel->links.dump_io_uring_buf));
>>> +	if (!ASSERT_GE(iter_fd, 0, "bpf_iter_create"))
>>> +		goto end_close_fd;
>>> +
>>> +	ret = read_fd_into_buffer(iter_fd, rbuf, sizeof(rbuf));
>>> +	if (!ASSERT_GT(ret, 0, "read_fd_into_buffer"))
>>> +		goto end_close_iter;
>>> +
>>> +	ASSERT_OK(strcmp(rbuf, buf), "compare iterator output");
>>> +
>>> +	puts("=== Expected Output ===");
>>> +	printf("%s", buf);
>>> +	puts("==== Actual Output ====");
>>> +	printf("%s", rbuf);
>>> +	puts("=======================");
>>
>> Maybe you can do an actual comparison and use ASSERT_* macros to check
>> result?
>>
> 
> I already did that in the line above first "puts". The printing is just for
> better debugging, to show the incorrect output in case test fails. Also in epoll
> test in the next patch the order of entries is not fixed, since they are sorted
> using struct file pointer.

I see, maybe the following which prints out details only if failure?

	if (!ASSERT_OK(strcmp(rbuf, buf), "compare iterator output")) {
		puts("=== ...");
		...
	}

> 
>>> +
>>> +end_close_iter:
>>> +	close(iter_fd);
>>> +end_close_fd:
>>> +	close(fd);
>>> +end:
>>> +	while (i--)
>>> +		munmap(iovs[i].iov_base, iovs[i].iov_len);
>>> +	bpf_iter_io_uring__destroy(skel);
>>> +}
>>> +
[...]