On Sat, May 11, 2019 at 08:17:47AM +0200, Knut Omang wrote: > On Fri, 2019-05-10 at 15:18 -0700, Frank Rowand wrote: > > On 5/10/19 1:54 PM, Brendan Higgins wrote: > > > On Fri, May 10, 2019 at 5:13 AM Knut Omang <knut.omang@xxxxxxxxxx> wrote: > > >> On Fri, 2019-05-10 at 03:23 -0700, Brendan Higgins 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? Or is the plan to unify the KTF and > > >>> > > >>> I am not certain about KTF's upstream plans, but I assume that Knut > > >>> would have CC'ed me on the thread if he had started working on it. > > >> > > >> You are on the Github watcher list for KTF? > > > > > > Yep! I have been since LPC in 2017. > > > > > >> Quite a few of the commits there are preparatory for a forthcoming kernel patch set. > > >> I'll of course CC: you on the patch set when we send it to the list. > > > > > > Awesome! I appreciate it. > > > > > >> > > >>>> Kunit in-kernel test harnesses? Because there's tons of these > > >>> > > >>> No, no plan. Knut and I talked about this a good while ago and it > > >>> seemed that we had pretty fundamentally different approaches both in > > >>> terms of implementation and end goal. Combining them seemed pretty > > >>> infeasible, at least from a technical perspective. Anyway, I am sure > > >>> Knut would like to give him perspective on the matter and I don't want > > >>> to say too much without first giving him a chance to chime in on the > > >>> matter. > > >> > > >> I need more time to study KUnit details to say, but from a 10k feet perspective: > > >> I think at least there's a potential for some API unification, in using the same > > macro > > >> names. How about removing the KUNIT_ prefix to the test macros ;-) ? > > > > > > Heh, heh. That's actually the way I had it in the earliest versions of > > > KUnit! But that was pretty much the very first thing everyone > > > complained about. I think I went from no prefix (like you are > > > suggesting) to TEST_* before the first version of the RFC at the > > > request of several people I was kicking the idea around with, and then > > > I think I was asked to go from TEST_* to KUNIT_* in the very first > > > revision of the RFC. > > > > > > In short, I am sympathetic to your suggestion, but I think that is > > > non-negotiable at this point. The community has a clear policy in > > > place on the matter, and at this point I would really prefer not to > > > change all the symbol names again. > > > > This would not be the first time that a patch submitter has been > > told "do B instead of A" for version 1, then told "do C instead of > > B" for version 2, then told "do A instead of C" for the final version. > > > > It sucks, but it happens. Sure, I have been there before, but I thought those original opinions were based on a pretty well established convention. Also, I don't think those original opinions have changed. If they have, please chime in and correct me. > Sorry, I must have overlooked the B instead of A instance - otherwise > I would have objected against it - in addition to the recognizability > and portability issue I think it is important that these primitives are > not unnecessary long since they will be written a *lot* of times if things go > our way. I get that. That is why I thought I might have been worthy of an exception. It is definitely easier to write EXPECT_EQ(...) than KUNIT_EXPECT_EQ(...) or TEST_EXPECT_EQ(...), but no one else seemed to agree in the past. Even now, it is only you (and maybe Frank?) telling me to change it; I would like to maybe hear Shuah, Kees, or Greg chime in on this before I go about actually chaning it back, as I distinctly remember each of them telling me that I should go with KUNIT_*. > And the reason for using unique names elsewhere is to be able to co-exist with > other components with the same needs. In the case of tests, I believe they are That's the policy I was talking about. > in a different category, they are not supposed to be part of production kernels, > and we want them to be used all over, that should warrant having the ASSERT_ and EXPECT_ > prefixes "reserved" for the purpose, so I would urge some pragmatism here! I don't disagree. Again, this is what I initially proposed, but no one agreed with me on this point. I am not saying no. Nevertheless, this is a pretty consistently applied pattern for new stuff, and I would really prefer not to make waves on something that really doesn't matter all that much. So like I said, if we can get some more discussion on this and it seems like broad consensus says we can reserve ASSERT_* and EXPECT_*, then I will go along with it. > > As an aside, can you point to where the "clear policy in place" is > > documented, and what the policy is? Global namespacing policy that Knut mentioned above. > > > > -Frank > > > > > > >> That would make the names shorter, saving typing when writing tests, and storage ;-) > > >> and also make the names more similar to KTF's, and those of user land unit test > > > > > > You mean the Googletest/Googlemock expectations/assertions? > > > > > > It's a great library (with not so great a name), but unfortunately it > > > is written in C++, which I think pretty much counts it out here. > > Using a similar syntax is a good thing, since it makes it easier for people > who write tests in user land frameworks to contribute to the kernel tests. > And if, lets say, someone later comes up with a way to run the KUnit tests in "real" > user land within Googletest ;-) then less editing would be needed.. > > > >> frameworks? Also it will make it possible to have functions compiling both with KTF > > and > > >> KUnit, facilitating moving code between the two. > > > > > > I think that would be cool, but again, I don't think this will be > > > possible with Googletest/Googlemock. > > I was thinking of moves between KUnit tests and KTF tests, kernel code only. > Some test functions may easily be usable both in a "pure" mocking environment > and in an integrated setting with hardware/driver/userspace dependencies. Speaking for KUnit, you are right. I got KUnit working on other architectures a couple revisions ago (apparently I didn't advertise that well enough). > > >> > > >> Also the string stream facilities of KUnit looks interesting to share. > > > > > > I am glad you think so! > > > > > > If your biggest concern on my side is test macro names (which I think > > > is a no-go as I mentioned above), I think we should be in pretty good > > > shape once you are ready to move forward. Besides, I have a lot more > > > KUnit patches coming after this: landing this patchset is just the > > > beginning. So how about we keep moving forward on this patchset? > > I think the importance of a well thought through > test API definition is not to be underestimated I agree. That is why I am saying that I think we are in good shape if we are only arguing about the name. > - the sooner we can unify and establish a common base, the better, > I think. Again, I agree. That is what I am trying to do here. > > My other concern is, as mentioned earlier, whether UML is really that > different from just running in a VM wrt debugging support, and that > there exists a better approach based on automatically generating > an environment where the test code and the source under test > can be compiled in a normal user land program. But it seems > there are enough clients of the UML approach to justify it > as a lightweight entry. We want to make it easy and inexcusable > not to test the code, having a low bar of entry is certainly good. Yep. > Other than that, I really would need to spend some more time with > the details on KUnit to verify my so far fairly > shallow observations! Are we arguing about anything other than naming schemes here? If that's it, we can refactor the under the hood stuff later; if we even need to at all. Cheers!
