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

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Message-ID: <CABVgOSmO3cH_oDN1sNWaNYRy8uLxHHUkWPhTevWhHgMjd4LQ5g@mail.gmail.com>
Date:   Wed, 9 Aug 2023 20:11:08 +0800
From:   David Gow <davidgow@...gle.com>
To:     Richard Fitzgerald <rf@...nsource.cirrus.com>
Cc:     Rae Moar <rmoar@...gle.com>, brendan.higgins@...ux.dev,
        linux-kselftest@...r.kernel.org, kunit-dev@...glegroups.com,
        linux-kernel@...r.kernel.org, patches@...nsource.cirrus.com
Subject: Re: [PATCH v2 2/6] kunit: kunit-test: Add test cases for extending
 log buffer

On Wed, 9 Aug 2023 at 17:39, Richard Fitzgerald
<rf@...nsource.cirrus.com> wrote:
>
> On 8/8/23 22:16, Rae Moar wrote:
> > On Tue, Aug 8, 2023 at 8:35 AM Richard Fitzgerald
> > <rf@...nsource.cirrus.com> 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@...nsource.cirrus.com>
> >
> > 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

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