On Fri, Feb 07, 2025 at 03:14:01PM -0500, Tamir Duberstein wrote:
This is one of just 3 remaining "Test Module" kselftests (the others being printf and scanf), the rest having been converted to KUnit.
I tested this using:
$ tools/testing/kunit/kunit.py run --arch arm64 --make_options LLVM=1 bitmap.
I've already sent out a conversion series for each of printf[0] and scanf[1].
There was a previous attempt[2] to do this in July 2024. Please bear with me as I try to understand and address the objections from that time. I've spoken with Muhammad Usama Anjum, the author of that series, and received their approval to "take over" this work. Here we go...
Take over means that you'd at least add the Co-developed-by tag.
On 7/26/24 11:45 PM, John Hubbard wrote:
This changes the situation from "works for Linus' tab completion case", to "causes a tab completion problem"! :)
I think a tests/ subdir is how we eventually decided to do this [1], right?
So:
lib/tests/bitmap_kunit.c[1] https://lore.kernel.org/20240724201354.make.730-kees@kernel.org
This is true and unfortunate, but not trivial to fix because new kallsyms tests were placed in lib/tests in commit 84b4a51fce4c ("selftests: add new kallsyms selftests") *after* the KUnit filename best practices were adopted.
I propose that the KUnit maintainers blaze this trail using `string_kunit.c` which currently still lives in lib/ despite the KUnit docs giving it as an example at lib/tests/.
On 7/27/24 12:24 AM, Shuah Khan wrote:
This change will take away the ability to run bitmap tests during boot on a non-kunit kernel.
Nack on this change. I wan to see all tests that are being removed from lib because they have been converted - also it doesn't make sense to convert some tests like this one that add the ability test during boot.
This point was also discussed in another thread[3] in which:
On 7/27/24 12:35 AM, Shuah Khan wrote:
Please make sure you aren't taking away the ability to run these tests during boot.
It doesn't make sense to convert every single test especially when it is intended to be run during boot without dependencies - not as a kunit test but a regression test during boot.
bitmap is one example - pay attention to the config help test - bitmap one clearly states it runs regression testing during boot. Any test that says that isn't a candidate for conversion.
I am going to nack any such conversions.
The crux of the argument seems to be that the config help text is taken to describe the author's intent with the fragment "at boot". I think
KUNIT is disabled in defconfig, at least on x86_64. It is also disabled on my Ubuntu 24.04 machine. If I take your patches, I'll be unable to boot-test bitmaps. Even worse, I'll be unable to build the standalone test from sources as a module and load it later.
Or I misunderstand it, and there's a way to build some particular KUNIT test without enabling KUNIT in config and/or re-compiling the whole kernel? Please teach me, if so
Unless you give me a way to build and run the test in true production environment, I'm not going with KUNITs. Sorry.
this may be a case of confirmation bias: I see at least the following KUnit tests with "at boot" in their help text:
- CPUMASK_KUNIT_TEST
This one doesn't count because the test was not converted, it's originally written as a KUNIT test. I am happy when people bring new tests in the most comfortable way for them, and I don't want to push them to use this framework or another. So I didn't object, and I'm thankful for this contribution to Sander.
- BITFIELD_KUNIT
Same here. Plus, it was written long before I took over bitfields.
- CHECKSUM_KUNIT
- UTIL_MACROS_KUNIT
It seems to me that the inference being made is that any test that runs "at boot" is intended to be run by both developers and users, but I find no evidence that bitmap in particular would ever provide additional value when run by users.
This is my evidence: sometimes people report performance or whatever issues on their systems, suspecting bitmaps guilty. I ask them to run the bitmap or find_bit test to narrow the problem. Sometimes I need to test a hardware I have no access to, and I have to (kindly!) ask people to build a small test and run it. I don't want to ask them to rebuild the whole kernel, or even to build something else.
https://lore.kernel.org/all/YuWk3titnOiQACzC@yury-laptop/
There's further discussion about KUnit not being "ideal for cases where people would want to check a subsystem on a running kernel", but I find no evidence that bitmap in particular is actually testing the running kernel; it is a unit test of the bitmap functions, which is also stated in the config help text.
David Gow made many of the same points in his final reply[4], which was never replied to.
Nice summary for the discussion. Unfortunately you missed my concerns. Which are:
Pros: - Now we switch to KUNITs because KUNITs are so good
Cons: - Wipes git history; - Bloats the test's source code; - Adds dependencies; - Doesn't run on most popular distros and defconfig;
So, no.
Thanks, Yury
Link: https://lore.kernel.org/all/20250207-printf-kunit-convert-v2-0-057b23860823@... [0] Link: https://lore.kernel.org/all/20250207-scanf-kunit-convert-v4-0-a23e2afaede8@g... [1] Link: https://lore.kernel.org/all/20240726110658.2281070-1-usama.anjum@collabora.c... [2] Link: https://lore.kernel.org/all/327831fb-47ab-4555-8f0b-19a8dbcaacd7@collabora.c... [3] Link: https://lore.kernel.org/all/CABVgOSmMoPD3JfzVd4VTkzGL2fZCo8LfwzaVSzeFimPrhgL... [4]
Thanks for your attention.
Signed-off-by: Tamir Duberstein tamird@gmail.com
Tamir Duberstein (3): bitmap: remove _check_eq_u32_array bitmap: convert self-test to KUnit bitmap: break kunit into test cases
MAINTAINERS | 2 +- arch/m68k/configs/amiga_defconfig | 1 - arch/m68k/configs/apollo_defconfig | 1 - arch/m68k/configs/atari_defconfig | 1 - arch/m68k/configs/bvme6000_defconfig | 1 - arch/m68k/configs/hp300_defconfig | 1 - arch/m68k/configs/mac_defconfig | 1 - arch/m68k/configs/multi_defconfig | 1 - arch/m68k/configs/mvme147_defconfig | 1 - arch/m68k/configs/mvme16x_defconfig | 1 - arch/m68k/configs/q40_defconfig | 1 - arch/m68k/configs/sun3_defconfig | 1 - arch/m68k/configs/sun3x_defconfig | 1 - arch/powerpc/configs/ppc64_defconfig | 1 - lib/Kconfig.debug | 24 +- lib/Makefile | 2 +- lib/{test_bitmap.c => bitmap_kunit.c} | 454 +++++++++++++--------------------- tools/testing/selftests/lib/bitmap.sh | 3 - tools/testing/selftests/lib/config | 1 - 19 files changed, 195 insertions(+), 304 deletions(-)
base-commit: 2014c95afecee3e76ca4a56956a936e23283f05b change-id: 20250207-bitmap-kunit-convert-92d3147b2eee
Best regards,
Tamir Duberstein tamird@gmail.com