Re: [PATCH v3 5/7] kunit: kunit-test: Add test cases for logging very long lines

Rae Moar
2023-08-10T22:59:01Z

On Wed, Aug 9, 2023 at 10:54 AM 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 *test)
> 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 = kunit_kzalloc(test, sizeof(frag->buf) * 6, GFP_KERNEL);
> + KUNIT_ASSERT_NOT_ERR_OR_NULL(test, line);
> + memset(line, 'x', (sizeof(frag->buf) * 6) - 1);
> + kunit_log_append(suite.log, "%s", line);
> + p = 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 = 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] = '\n';
> + kunit_log_append(suite.log, "%s", line);
> + p = 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 kunit *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 = kunit_kzalloc(test, sizeof(*suite.log), GFP_KERNEL);
> + KUNIT_ASSERT_NOT_ERR_OR_NULL(test, suite.log);
> + INIT_LIST_HEAD(suite.log);
> + frag = 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 = sizeof(frag->buf) * 6;
> + line = kunit_kmalloc(test, line_buf_size, GFP_KERNEL);
> + KUNIT_ASSERT_NOT_ERR_OR_NULL(test, line);
> + line[0] = '\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 = 0;
> + do {
> + static const char fill[] =
> + "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
> +
> + i = prandom_u32_state(&rnd) % (sizeof(fill) - 1);
> + len = strlcat(line, &fill[i], line_buf_size);
> + } while (len < line_buf_size);
> +
> + kunit_log_append(suite.log, "%s\n", line);
> +
> + p = 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, strlen(p));
> +
> + /* Don't compare the trailing '\n' */
> + pn = strrchr(p, '\n');
> + KUNIT_EXPECT_NOT_ERR_OR_NULL(test, pn);
> + *pn = '\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[] = {
> KUNIT_CASE(kunit_log_init_frag_test),
> KUNIT_CASE(kunit_log_test),
> @@ -806,6 +887,7 @@ static struct kunit_case kunit_log_test_cases[] = {
> 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
>