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@xxxxxxxxxx
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@xxxxxxxxx/T/#u [0]
Link: https://lore.kernel.org/all/20250207-scanf-kunit-convert-v4-0-a23e2afaede8@xxxxxxxxx/T/#u [1]
Link: https://lore.kernel.org/all/20240726110658.2281070-1-usama.anjum@xxxxxxxxxxxxx/T/#u [2]
Link: https://lore.kernel.org/all/327831fb-47ab-4555-8f0b-19a8dbcaacd7@xxxxxxxxxxxxx/T/#u [3]
Link: https://lore.kernel.org/all/CABVgOSmMoPD3JfzVd4VTkzGL2fZCo8LfwzaVSzeFimPrhgLa5w@xxxxxxxxxxxxxx/ [4]
Thanks for your attention.
Signed-off-by: Tamir Duberstein <tamird@xxxxxxxxx>
---
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@xxxxxxxxx>
