kunit: fix executor OOM error handling logic on non-UML

The existing logic happens to work fine on UML, but is not correct when
running on other arches.

1. We didn't initialize `int err`, and kunit_filter_suites() doesn't
   explicitly set it to 0 on success. So we had false "failures".
   Note: it doesn't happen on UML, causing this to get overlooked.
2. If we error out, we do not call kunit_handle_shutdown().
   This makes kunit.py timeout when using a non-UML arch, since the QEMU
   process doesn't ever exit.

Fixes: a02353f4 ("kunit: bail out of test filtering logic quicker if OOM")
Signed-off-by: Daniel Latypov <dlatypov@google.com>
Reviewed-by: Brendan Higgins <brendanhiggins@google.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

lib/kunit/executor.c

@@ -247,13 +247,13 @@ int kunit_run_all_tests(void)
 		.start = __kunit_suites_start,
 		.end = __kunit_suites_end,
 	};
-	int err;
+	int err = 0;
 
 	if (filter_glob_param) {
 		suite_set = kunit_filter_suites(&suite_set, filter_glob_param, &err);
 		if (err) {
 			pr_err("kunit executor: error filtering suites: %d\n", err);
-			return err;
+			goto out;
 		}
 	}
 
@@ -268,9 +268,10 @@ int kunit_run_all_tests(void)
 		kunit_free_suite_set(suite_set);
 	}
 
-	kunit_handle_shutdown();
 
-	return 0;
+out:
+	kunit_handle_shutdown();
+	return err;
 }
 
 #if IS_BUILTIN(CONFIG_KUNIT_TEST)