Re: [PATCH v2 2/6] kunit: kunit-test: Add test cases for extending log buffer

From: Richard Fitzgerald
Date: Wed Aug 09 2023 - 08:14:17 EST


On 9/8/23 13:11, David Gow wrote:
On Wed, 9 Aug 2023 at 17:39, Richard Fitzgerald
<rf@xxxxxxxxxxxxxxxxxxxxx> wrote:

On 8/8/23 22:16, Rae Moar wrote:
On Tue, Aug 8, 2023 at 8:35 AM Richard Fitzgerald
<rf@xxxxxxxxxxxxxxxxxxxxx> wrote:

Add test cases for the dynamically-extending log buffer.

kunit_log_extend_test_1() logs a series of numbered lines then tests
that the resulting log contains all the lines.

kunit_log_extend_test_2() logs a large number of lines of varying length
to create many fragments, then tests that all lines are present.

kunit_log_frag_sized_line_test() logs a line that exactly fills a
fragment. This should not cause an extension of the log or truncation
of the line.

kunit_log_newline_test() has a new test to append a line that is exactly
the length of the available space in the current fragment and check that
the resulting log has a trailing '\n'.

Signed-off-by: Richard Fitzgerald <rf@xxxxxxxxxxxxxxxxxxxxx>

Hello!

I am happy to see so many tests in this patch series. I've been
working with these patches and the debugfs logs seem to be working
well.

However, when I ran the new kunit-log-test tests three of the tests
failed: kunit_log_extend_test_1(), kunit_log_extend_test_2(), and
kunit_log_newline_test().

The diagnostic info for kunit_log_extend_test_1() reports:

[20:55:27] # kunit_log_extend_test_1: EXPECTATION FAILED at
lib/kunit/kunit-test.c:705
[20:55:27] Expected p == line, but
[20:55:27] p == "xxxxxx…xxxx12345678"
[20:55:27] line == "The quick brown fox jumps over the lazy penguin 0"

[20:55:27] # kunit_log_extend_test_1: EXPECTATION FAILED at
lib/kunit/kunit-test.c:705
[20:55:27] Expected p == line, but
[20:55:27] p == "The quick brown fox jumps over the lazy penguin 1"
[20:55:27] line == "The quick brown fox jumps over the lazy penguin 4"
[20:55:27] # kunit_log_extend_test_1: EXPECTATION FAILED at
lib/kunit/kunit-test.c:705
[20:55:27] Expected p == line, but
[20:55:27] p == "The quick brown fox jumps over the lazy penguin 2"
[20:55:27] line == "The quick brown fox jumps over the lazy penguin 5"

[20:55:27] # kunit_log_extend_test_1: EXPECTATION FAILED at
lib/kunit/kunit-test.c:709
[20:55:27] Expected i == num_lines, but
[20:55:27] i == 64 (0x40)
[20:55:27] num_lines == 141 (0x8d)

So it looks like the log contains a different number of lines than
expected which is causing the difference of 3 between expected and
what was obtained. Potentially the log is not getting cleared/freed
properly in between test cases?

The diagnostic info for kunit_log_extend_test_2() reports:

[20:55:27] # kunit_log_extend_test_2: EXPECTATION FAILED at
lib/kunit/kunit-test.c:776
[20:55:27] Expected p == &line[i], but
[20:55:27] p ==
"xxxxx...xxxxx123456780123456789abcdef101112131415161718191a1b1c1d1e1f202122232425262728292a2b2c2d2e2f30313233343536373839"
[20:55:27] &line[i] ==
"0123456789abcdef101112131415161718191a1b1c1d1e1f202122232425262728292a2b2c2d2e2f30313233343536373839"
[20:55:27] # kunit_log_extend_test_2: EXPECTATION FAILED at
lib/kunit/kunit-test.c:781
[20:55:27] Expected n == num_lines, but
[20:55:27] n == 147 (0x93)
[20:55:27] num_lines == 155 (0x9b)
[20:55:27] Not enough lines.

Similar difference in the number of lines here.

The diagnostic info for kunit_log_newline_test() reports that the test
fails on this line:

KUNIT_EXPECT_EQ(test, p[strlen(p) - 1], '\n');

Let me know if you are seeing similar errors. I can post the full log
if that would be helpful.

-Rae


Ah, I see a bug in get_concatenated_log().
Does this change fix it for you?

len++; /* for terminating '\0' */
- p = kunit_kmalloc(test, len, GFP_KERNEL);
+ p = kunit_kzalloc(test, len, GFP_KERNEL);

This fixes what seems to be the same issue for me, under x86_64/qemu.

Thanks,
-- David

Good. It seems that the various memory security options have the
side-effect of covering up this bug. I don't know which one exactly
(I've just turned them all off). I had been testing with them on.

I'll send a V3.