Messages in this thread | | | Subject | Re: [PATCH] lib/math/rational.c: Fix divide by zero | From | Randy Dunlap <> | Date | Mon, 24 May 2021 18:49:09 -0700 |
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On 5/24/21 5:42 PM, David Gow wrote: > On Tue, May 25, 2021 at 7:38 AM Daniel Latypov <dlatypov@google.com> wrote: >> >> On Mon, May 24, 2021 at 4:30 PM Randy Dunlap <rdunlap@infradead.org> wrote: >>> >>> On 5/24/21 3:56 PM, Daniel Latypov wrote: >>>> On Mon, May 24, 2021 at 3:04 PM Randy Dunlap <rdunlap@infradead.org> wrote: >>>>> >>>>> On 5/24/21 9:55 AM, Daniel Latypov wrote: >>>>>> diff --git a/lib/math/Kconfig b/lib/math/Kconfig >>>>>> index f19bc9734fa7..20460b567493 100644 >>>>>> --- a/lib/math/Kconfig >>>>>> +++ b/lib/math/Kconfig >>>>>> @@ -15,3 +15,14 @@ config PRIME_NUMBERS >>>>>> >>>>>> config RATIONAL >>>>>> bool >>>>>> + >>>>>> +config RATIONAL_KUNIT_TEST >>>>>> + tristate "KUnit test for rational number support" if !KUNIT_ALL_TESTS >>>>>> + # depends on KUNIT && RATIONAL # this is how it should work, but >>>>>> + depends on KUNIT >>>>>> + select RATIONAL # I don't grok kconfig enough to know why this >>>>> >>>>> Only to set the symbol CONFIG_RATIONAL. >>>>> Then when 'make' descends into the lib/math/ subdir and looks at its Makefile, >>>>> it will decide to build the binary rational.o. >>>>> >>>>> obj-$(CONFIG_RATIONAL) += rational.o >>>>> >>>> >>>> Ack, I understand that much. >>> >>> Oh! Clearly I misunderstood the problem. >>> >>> I had to look thru 60 config files before I found one where CONFIG_RATIONAL >>> was not set. >>> >>> And I'm still not sure, but I believe that it's because it has to be set >>> by some other Kconfig entry doing a 'select' on it. >>> >>> Here are the kconfigs that select it (on i386, where I found it not set): >>> >>> - COMMON_CLK [=n] && !HAVE_LEGACY_CLK [=n] >>> - SERIAL_8250_LPSS [=n] && TTY [=n] && HAS_IOMEM [=y] && SERIAL_8250 [=n] && PCI [=n] && (X86 [=y] || COMPILE_TEST [=y]) >>> - SERIAL_8250_MID [=n] && TTY [=n] && HAS_IOMEM [=y] && SERIAL_8250 [=n] && PCI [=n] && (X86 [=y] || COMPILE_TEST [=y]) >>> - SERIAL_IMX [=n] && TTY [=n] && HAS_IOMEM [=y] && (ARCH_MXC || COMPILE_TEST [=y]) >>> - VIDEO_V4L2 [=n] && MEDIA_SUPPORT [=n] && (I2C [=y] || I2C [=y]=n) && VIDEO_DEV [=n] >>> - SND_SOC_ROCKCHIP_PDM [=n] && SOUND [=n] && !UML && SND [=n] && SND_SOC [=n] && CLKDEV_LOOKUP [=n] && SND_SOC_ROCKCHIP [=n] >>> - COMMON_CLK_QCOM [=n] && COMMON_CLK [=n] && OF [=y] && (ARCH_QCOM || COMPILE_TEST [=y]) >>> >>> but my test config has none of those enabled, so I cannot set RATIONAL. >>> >>> I guess the easiest solution is to have KUNIT or some sub-KUNIT test >>> just select RATIONAL. >> >> Yeah, the easiest thing would be to keep the `select RATIONAL` that I >> showed in the example patch. >> >> +David Gow +Brendan Higgins as they both particularly wanted to avoid >> having any tests `select` their dependencies, however. >> > > This came from a thread[1], and one of the causes behind it was not > wanting to have KUNIT_ALL_TESTS enable things like filesystems and > drivers which wouldn't otherwise be built.
Ah yes, I recognize that thread.
> Personally, I think that RATIONAL is probably an okay thing to select > here: it's not as heavyweight as drivers/filesystems/etc, and our > general guidance here is "avoid select where sensible to do so", not > "don't use it under any circumstances".
RATIONAL does not have a prompt string, so depending on it would not be reliable. I.e., it is meant to be selected.
> The other option would be to have a separate config entry which just > selected RATIONAL, but even I think that's probably uglier, however > nice it is for guaranteeing flexibility.
Yes, that's even worse.
> [1]: https://lore.kernel.org/linux-ext4/52959e99-4105-3de9-730c-c46894b82bdd@infradead.org/T/#t > >>> >>>> My confusion is why this doesn't work: >>>> >>>> $ ./tools/testing/kunit/kunit.py run --kunitconfig /dev/stdin <<EOF >>>> CONFIG_KUNIT=y >>>> CONFIG_RATIONAL=y >>>> EOF >>>> ... >>>> ERROR:root:Provided Kconfig is not contained in validated .config. >>>> Following fields found in kunitconfig, but not in .config: >>>> CONFIG_RATIONAL=y >>>> >>>> What it's complaining about is that `make ARCH=um olddefconfig` is >>>> leaving CONFIG_RATIONAL=y unset. >>>> >>>> Stripping out kunit.py, it's this: >>>> >>>> $ echo -e 'CONFIG_KUNIT=y\nCONFIG_RATIONAL=y' > .kunit/.config >>>> $ make ARCH=um olddefconfig O=.kunit >>>> $ grep RATIONAL .kunit/.config >>>> >>>> I'm not versed in Kconfig enough to know why CONFIG_RATIONAL=y is >>>> getting removed. >>>> >>>>> >>>>>> is necessary >>>>>> + default KUNIT_ALL_TESTS >>>>>> + help >>>>>> + This builds unit tests for the rational number support. >>>>>> + >>>>>> + If unsure, say N.
-- ~Randy
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