On Wed, Jul 20, 2022 at 05:26:02PM +0800, David Gow wrote:
On Wed, Jul 20, 2022 at 1:58 AM Luis Chamberlain mcgrof@kernel.org wrote:
On Wed, Jul 13, 2022 at 08:24:32AM -0700, Daniel Latypov wrote:
On Tue, Jul 12, 2022 at 5:52 PM David Gow davidgow@google.com wrote:
The new KUnit module handling has KUnit test suites listed in a .kunit_test_suites section of each module. This should be loaded when the module is, but at the moment this only happens if KUnit is built-in.
Also load this when KUnit is enabled as a module: it'll not be usable unless KUnit is loaded, but such modules are likely to depend on KUnit anyway, so it's unlikely to ever be loaded needlessly.
This seems reasonable to me.
Question: what happens in this case?
- insmod <test-module>
- insmod kunit
- rmmod <test-module>
I think on 3, we'll call the cleanup code, __kunit_test_suites_exit(), for <test-module>, I think? But we never called __kunit_test_suites_init(). My fear is what breaks as a result of this precondition break.
I don't think this should be possible: any module with KUnit tests will depend on the 'kunit' module (or, at least, kunit symbols), so shouldn't load without kunit already present.
If modprobe is used, kunit will automatically be loaded. If insmod is used directly, loading the first module should error out with something like: [ 82.393629] list_test: loading test module taints kernel. [ 82.409607] list_test: Unknown symbol kunit_binary_ptr_assert_format (err -2) [ 82.409657] list_test: Unknown symbol kunit_do_failed_assertion (err -2) [ 82.409799] list_test: Unknown symbol kunit_binary_assert_format (err -2) [ 82.409820] list_test: Unknown symbol kunit_unary_assert_format (err -2) insmod: ERROR: could not insert module /lib/modules/5.19.0-rc1-15284-g9ec67db0c271/kernel/lib/list-test.ko: Unknown symbol in module
This can be fixed with a request_module() call. And since this is a generic requirement, you can have the wrappers do it for you.
Maybe you could get into some trouble by force-removing modules at various points, but you're in undefined behaviour generally at that point, so I don't think there's much point going out-of-our-way to try to support that.
You can prevent that by refcounting the kunit module / symbols, by each test.
Luis