On Fri, 2019-05-10 at 10:12 +0200, Daniel Vetter wrote: > On Fri, May 10, 2019 at 7:49 AM Knut Omang <knut.omang@xxxxxxxxxx> wrote: > > > > On Thu, 2019-05-09 at 22:18 -0700, Frank Rowand wrote: > > > On 5/9/19 4:40 PM, Logan Gunthorpe wrote: > > > > > > > > > > > > On 2019-05-09 5:30 p.m., Theodore Ts'o wrote: > > > >> On Thu, May 09, 2019 at 04:20:05PM -0600, Logan Gunthorpe wrote: > > > >>> > > > >>> The second item, arguably, does have significant overlap with kselftest. > > > >>> Whether you are running short tests in a light weight UML environment or > > > >>> higher level tests in an heavier VM the two could be using the same > > > >>> framework for writing or defining in-kernel tests. It *may* also be valuable > > > >>> for some people to be able to run all the UML tests in the heavy VM > > > >>> environment along side other higher level tests. > > > >>> > > > >>> Looking at the selftests tree in the repo, we already have similar items to > > > >>> what Kunit is adding as I described in point (2) above. kselftest_harness.h > > > >>> contains macros like EXPECT_* and ASSERT_* with very similar intentions to > > > >>> the new KUNIT_EXECPT_* and KUNIT_ASSERT_* macros. > > > >>> > > > >>> However, the number of users of this harness appears to be quite small. Most > > > >>> of the code in the selftests tree seems to be a random mismash of scripts > > > >>> and userspace code so it's not hard to see it as something completely > > > >>> different from the new Kunit: > > > >>> > > > >>> $ git grep --files-with-matches kselftest_harness.h * > > > >> > > > >> To the extent that we can unify how tests are written, I agree that > > > >> this would be a good thing. However, you should note that > > > >> kselftest_harness.h is currently assums that it will be included in > > > >> userspace programs. This is most obviously seen if you look closely > > > >> at the functions defined in the header files which makes calls to > > > >> fork(), abort() and fprintf(). > > > > > > > > Ah, yes. I obviously did not dig deep enough. Using kunit for > > > > in-kernel tests and kselftest_harness for userspace tests seems like > > > > a sensible line to draw to me. Trying to unify kernel and userspace > > > > here sounds like it could be difficult so it's probably not worth > > > > forcing the issue unless someone wants to do some really fancy work > > > > to get it done. > > > > > > > > Based on some of the other commenters, I was under the impression > > > > that kselftests had in-kernel tests but I'm not sure where or if they > > > > exist. > > > > > > YES, kselftest has in-kernel tests. (Excuse the shouting...) > > > > > > Here is a likely list of them in the kernel source tree: > > > > > > $ grep module_init lib/test_*.c > > > lib/test_bitfield.c:module_init(test_bitfields) > > > lib/test_bitmap.c:module_init(test_bitmap_init); > > > lib/test_bpf.c:module_init(test_bpf_init); > > > lib/test_debug_virtual.c:module_init(test_debug_virtual_init); > > > lib/test_firmware.c:module_init(test_firmware_init); > > > lib/test_hash.c:module_init(test_hash_init); /* Does everything */ > > > lib/test_hexdump.c:module_init(test_hexdump_init); > > > lib/test_ida.c:module_init(ida_checks); > > > lib/test_kasan.c:module_init(kmalloc_tests_init); > > > lib/test_list_sort.c:module_init(list_sort_test); > > > lib/test_memcat_p.c:module_init(test_memcat_p_init); > > > lib/test_module.c:static int __init test_module_init(void) > > > lib/test_module.c:module_init(test_module_init); > > > lib/test_objagg.c:module_init(test_objagg_init); > > > lib/test_overflow.c:static int __init test_module_init(void) > > > lib/test_overflow.c:module_init(test_module_init); > > > lib/test_parman.c:module_init(test_parman_init); > > > lib/test_printf.c:module_init(test_printf_init); > > > lib/test_rhashtable.c:module_init(test_rht_init); > > > lib/test_siphash.c:module_init(siphash_test_init); > > > lib/test_sort.c:module_init(test_sort_init); > > > lib/test_stackinit.c:module_init(test_stackinit_init); > > > lib/test_static_key_base.c:module_init(test_static_key_base_init); > > > lib/test_static_keys.c:module_init(test_static_key_init); > > > lib/test_string.c:module_init(string_selftest_init); > > > lib/test_ubsan.c:module_init(test_ubsan_init); > > > lib/test_user_copy.c:module_init(test_user_copy_init); > > > lib/test_uuid.c:module_init(test_uuid_init); > > > lib/test_vmalloc.c:module_init(vmalloc_test_init) > > > lib/test_xarray.c:module_init(xarray_checks); > > > > > > > > > > If they do exists, it seems like it would make sense to > > > > convert those to kunit and have Kunit tests run-able in a VM or > > > > baremetal instance. > > > > > > They already run in a VM. > > > > > > They already run on bare metal. > > > > > > They already run in UML. > > > > > > This is not to say that KUnit does not make sense. But I'm still trying > > > to get a better description of the KUnit features (and there are > > > some). > > > > FYI, I have a master student who looks at converting some of these to KTF, such as for > > instance the XArray tests, which lended themselves quite good to a semi-automated > > conversion. > > > > The result is also a somewhat more compact code as well as the flexibility > > provided by the Googletest executor and the KTF frameworks, such as running selected > > tests, output formatting, debugging features etc. > > So is KTF already in upstream? No.. > Or is the plan to unify the KTF and > Kunit in-kernel test harnesses? Since KTF delegates reporting and test running to user space - reporting is based on netlink communication with the user land frontend (Googletest based, but can in principle be ported to any user land framework if need be) - little specific test harness features are needed for KTF, so there's little if no direct overlap with the infrastructure in kselftests (as far as I understand, I'd like to spend more time on the details there..) > Because there's tons of these > in-kernel unit tests already, and every merge we get more (Frank's > list didn't even look into drivers or anywhere else, e.g. it's missing > the locking self tests I worked on in the past), and a more structured > approach would really be good. That's been my thinking too. Having a unified way to gradually move to would benefit anyone who needs to relate to these tests in that there will be less to learn. But that would be a long term evolutionary goal of course. Also I think each of these test suites/sets would benefit from being more available for running even in kernels not made specifically for testing, and I think using the module structure and a lean, common module (ktf.ko) as a library for the tests, but no "polluting" of the "production" kernel code with anything else, is a kind of a policy that comes implicitly with KTF that can make it easier to maintain a sort of standard "language" for writing kernel tests. Wrt KTF, we're working on making a suitable patch set for the kernel, but also have projects running internally that uses KTF as a standalone git repository, and that inspires new features and other changes, as well as a growing set of tests. I want to make sure we find a good candidate kernel integration that can coexist nicely with the separate git repo version without becoming too much of a back/forward porting challenge. Knut > -Daniel
