On 11/18/21 10:33 AM, Kumar Kartikeya Dwivedi wrote:

On Thu, Nov 18, 2021 at 11:24:19PM IST, Yonghong Song wrote:

quoted

On 11/15/21 9:42 PM, Kumar Kartikeya Dwivedi wrote:

quoted

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

[...]

quoted

quoted

+
+	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("=== ...");
		...
	}

quoted

quoted

+
+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);
+}
+

[...]