kunit: bail out of test filtering logic quicker if OOM

When filtering what tests to run (suites and/or cases) via
kunit.filter_glob (e.g. kunit.py run <glob>), we allocate copies of
suites.

These allocations can fail, and we largely don't handle that.
Note: realistically, this probably doesn't matter much.
We're not allocating much memory and this happens early in boot, so if
we can't do that, then there's likely far bigger problems.

This patch makes us immediately bail out from the top-level function
(kunit_filter_suites) with -ENOMEM if any of the underlying kmalloc()
calls return NULL.

Implementation note: we used to return NULL pointers from some functions
to indicate either that all suites/tests were filtered out or there was
an error allocating the new array.

We'll log a short error in this case and not run any tests or print a
TAP header. From a kunit.py user's perspective, they'll get a message
about missing/invalid TAP output and have to dig into the test.log to
see it. Since hitting this error seems so unlikely, it's probably fine
to not invent a way to plumb this error message more visibly.

See also: https://lore.kernel.org/linux-kselftest/20220329103919.2376818-1-lv.ruyi@zte.com.cn/

Signed-off-by: Daniel Latypov <dlatypov@google.com>
Reported-by: Zeal Robot <zealci@zte.com.cn>
Reported-by: Lv Ruyi <lv.ruyi@zte.com.cn>
Reviewed-by: Brendan Higgins <brendanhiggins@google.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

1 files changed, 3 insertions, 1 deletions

diff --git a/lib/kunit/executor_test.c b/lib/kunit/executor_test.c
index 4ed57fd94e42..eac6ff480273 100644
--- a/lib/kunit/executor_test.c
+++ b/lib/kunit/executor_test.c
@@ -137,14 +137,16 @@ static void filter_suites_test(struct kunit *test)
 		.end = suites + 2,
 	};
 	struct suite_set filtered = {.start = NULL, .end = NULL};
+	int err = 0;
 
 	/* Emulate two files, each having one suite */
 	subsuites[0][0] = alloc_fake_suite(test, "suite0", dummy_test_cases);
 	subsuites[1][0] = alloc_fake_suite(test, "suite1", dummy_test_cases);
 
 	/* Filter out suite1 */
-	filtered = kunit_filter_suites(&suite_set, "suite0");
+	filtered = kunit_filter_suites(&suite_set, "suite0", &err);
 	kfree_subsuites_at_end(test, &filtered); /* let us use ASSERTs without leaking */
+	KUNIT_EXPECT_EQ(test, err, 0);
 	KUNIT_ASSERT_EQ(test, filtered.end - filtered.start, (ptrdiff_t)1);
 
 	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, filtered.start);