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References: <20230809155438.22470-1-rf@opensource.cirrus.com> <20230809155438.22470-6-rf@opensource.cirrus.com>
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From:   Rae Moar <rmoar@google.com>
Date:   Thu, 10 Aug 2023 17:58:44 -0500
Message-ID: <CA+GJov5MH4Y72w4L7ue1OWp8747qOrm9fc4EPz7jzLrN7DtR9w@mail.gmail.com>
Subject: Re: [PATCH v3 5/7] kunit: kunit-test: Add test cases for logging very
 long lines
To:     Richard Fitzgerald <rf@opensource.cirrus.com>
Cc:     brendan.higgins@linux.dev, davidgow@google.com,
        linux-kselftest@vger.kernel.org, kunit-dev@googlegroups.com,
        linux-kernel@vger.kernel.org, patches@opensource.cirrus.com
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On Wed, Aug 9, 2023 at 10:54=E2=80=AFAM Richard Fitzgerald
<rf@opensource.cirrus.com> wrote:
>
> Add kunit_log_long_line_test() to test that logging a line longer than
> the buffer fragment size doesn't truncate the line.
>
> Add extra tests to kunit_log_newline_test() for lines longer than the
> buffer fragment size.
>
> Signed-off-by: Richard Fitzgerald <rf@opensource.cirrus.com>

Hello!

This test looks good to me. I have included just a few comments below.

Reviewed-by: Rae Moar <rmoar@google.com>

Thanks!
-Rae

> ---
>  lib/kunit/kunit-test.c | 84 +++++++++++++++++++++++++++++++++++++++++-
>  1 file changed, 83 insertions(+), 1 deletion(-)
>
> diff --git a/lib/kunit/kunit-test.c b/lib/kunit/kunit-test.c
> index 9ac81828d018..c079550c3afd 100644
> --- a/lib/kunit/kunit-test.c
> +++ b/lib/kunit/kunit-test.c
> @@ -609,7 +609,7 @@ static void kunit_log_newline_test(struct kunit *test=
)
>  {
>         struct kunit_suite suite;
>         struct kunit_log_frag *frag;
> -       char *p;
> +       char *p, *line;
>
>         kunit_info(test, "Add newline\n");
>         if (test->log) {
> @@ -635,6 +635,33 @@ static void kunit_log_newline_test(struct kunit *tes=
t)
>                 KUNIT_ASSERT_NOT_ERR_OR_NULL(test, p);
>                 KUNIT_EXPECT_NOT_NULL_MSG(test, strstr(p, "x12345678\n"),
>                         "Newline not appended when fragment is full. Log =
is:\n'%s'", p);
> +               kunit_kfree(test, p);
> +

I really like the thoroughness of this test. However, I do wonder if
this newline test could be broken into at least 2 parts as the test is
quite long with all these additions. I spoke on this in a previous
patch and just wanted to touch on it here as well.

> +               /* String that is much longer than a fragment */
> +               line =3D kunit_kzalloc(test, sizeof(frag->buf) * 6, GFP_K=
ERNEL);
> +               KUNIT_ASSERT_NOT_ERR_OR_NULL(test, line);
> +               memset(line, 'x', (sizeof(frag->buf) * 6) - 1);
> +               kunit_log_append(suite.log, "%s", line);
> +               p =3D get_concatenated_log(test, suite.log, NULL);
> +               KUNIT_ASSERT_NOT_ERR_OR_NULL(test, p);
> +               KUNIT_EXPECT_EQ(test, p[strlen(p) - 1], '\n');
> +               KUNIT_EXPECT_NULL(test, strstr(p, "\n\n"));
> +               kunit_kfree(test, p);
> +

I would also consider adding comments between these three cases to
describe their differences and maybe what the desired behavior would
be.

> +               kunit_log_append(suite.log, "%s\n", line);
> +               p =3D get_concatenated_log(test, suite.log, NULL);
> +               KUNIT_ASSERT_NOT_ERR_OR_NULL(test, p);
> +               KUNIT_EXPECT_EQ(test, p[strlen(p) - 1], '\n');
> +               KUNIT_EXPECT_NULL(test, strstr(p, "\n\n"));
> +               kunit_kfree(test, p);
> +
> +               line[strlen(line) - 1] =3D '\n';
> +               kunit_log_append(suite.log, "%s", line);
> +               p =3D get_concatenated_log(test, suite.log, NULL);
> +               KUNIT_ASSERT_NOT_ERR_OR_NULL(test, p);
> +               KUNIT_EXPECT_EQ(test, p[strlen(p) - 1], '\n');
> +               KUNIT_EXPECT_NULL(test, strstr(p, "\n\n"));
> +               kunit_kfree(test, p);
>         } else {
>                 kunit_skip(test, "only useful when debugfs is enabled");
>         }
> @@ -799,6 +826,60 @@ static void kunit_log_frag_sized_line_test(struct ku=
nit *test)
>  #endif
>  }
>
> +static void kunit_log_long_line_test(struct kunit *test)
> +{
> +#ifdef CONFIG_KUNIT_DEBUGFS
> +       struct kunit_suite suite;
> +       struct kunit_log_frag *frag;
> +       struct rnd_state rnd;
> +       char *line, *p, *pn;
> +       size_t line_buf_size, len;
> +       int num_frags, i;
> +
> +       suite.log =3D kunit_kzalloc(test, sizeof(*suite.log), GFP_KERNEL)=
;
> +       KUNIT_ASSERT_NOT_ERR_OR_NULL(test, suite.log);
> +       INIT_LIST_HEAD(suite.log);
> +       frag =3D kunit_kmalloc(test, sizeof(*frag), GFP_KERNEL);
> +       KUNIT_ASSERT_NOT_ERR_OR_NULL(test, frag);
> +       kunit_init_log_frag(frag);
> +       KUNIT_EXPECT_EQ(test, frag->buf[0], '\0');
> +       list_add_tail(&frag->list, suite.log);
> +
> +       /* Create a very long string to be logged */
> +       line_buf_size =3D sizeof(frag->buf) * 6;
> +       line =3D kunit_kmalloc(test, line_buf_size, GFP_KERNEL);
> +       KUNIT_ASSERT_NOT_ERR_OR_NULL(test, line);
> +       line[0] =3D '\0';
> +
> +       prandom_seed_state(&rnd, 3141592653589793238ULL);

I was a little worried about including a randomized string but since
it does not need to be reproduced here it should be fine. I also
haven't seen any issues with the tests with the randomized strings
being nondeterministic.

> +       len =3D 0;
> +       do {
> +               static const char fill[] =3D
> +                       "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuv=
wxyz";
> +
> +               i =3D prandom_u32_state(&rnd) % (sizeof(fill) - 1);
> +               len =3D strlcat(line, &fill[i], line_buf_size);
> +       } while (len < line_buf_size);
> +
> +       kunit_log_append(suite.log, "%s\n", line);
> +
> +       p =3D get_concatenated_log(test, suite.log, &num_frags);
> +       KUNIT_ASSERT_NOT_ERR_OR_NULL(test, p);
> +       KUNIT_EXPECT_GT(test, num_frags, 1);
> +
> +       kunit_info(test, "num_frags:%d total len:%zu\n", num_frags, strle=
n(p));
> +
> +       /* Don't compare the trailing '\n' */
> +       pn =3D strrchr(p, '\n');
> +       KUNIT_EXPECT_NOT_ERR_OR_NULL(test, pn);
> +       *pn =3D '\0';
> +       KUNIT_EXPECT_EQ(test, strlen(p), strlen(line));
> +       KUNIT_EXPECT_STREQ(test, p, line);
> +#else
> +       kunit_skip(test, "only useful when debugfs is enabled");
> +#endif
> +}
> +
>  static struct kunit_case kunit_log_test_cases[] =3D {
>         KUNIT_CASE(kunit_log_init_frag_test),
>         KUNIT_CASE(kunit_log_test),
> @@ -806,6 +887,7 @@ static struct kunit_case kunit_log_test_cases[] =3D {
>         KUNIT_CASE(kunit_log_extend_test_1),
>         KUNIT_CASE(kunit_log_extend_test_2),
>         KUNIT_CASE(kunit_log_frag_sized_line_test),
> +       KUNIT_CASE(kunit_log_long_line_test),
>         {}
>  };
>
> --
> 2.30.2
>