Re: [PATCH 1/7] watchdog/hardlockup: Sort hardlockup detector related config values a logical way

Doug Anderson
2023-06-07T23:34:56Z

Hi,

On Wed, Jun 7, 2023 at 8:25 AM Petr Mladek <pmladek@suse.com> wrote:
>
> There are four possible variants of hardlockup detectors:
>
> + buddy: available when SMP is set.
>
> + perf: available when HAVE_HARDLOCKUP_DETECTOR_PERF is set.
>
> + arch-specific: available when HAVE_HARDLOCKUP_DETECTOR_ARCH is set.
>
> + sparc64 special variant: available when HAVE_NMI_WATCHDOG is set
> and HAVE_HARDLOCKUP_DETECTOR_ARCH is not set.
>
> Only one hardlockup detector can be compiled in. The selection is done
> using quite complex dependencies between several CONFIG variables.
> The following patches will try to make it more straightforward.
>
> As a first step, reorder the definitions of the various CONFIG variables.
> The logical order is:
>
> 1. HAVE_* variables define available variants. They are typically
> defined in the arch/ config files.
>
> 2. HARDLOCKUP_DETECTOR y/n variable defines whether the hardlockup
> detector is enabled at all.
>
> 3. HARDLOCKUP_DETECTOR_PREFER_BUDDY y/n variable defines whether
> the buddy detector should be preferred over the perf one.
> Note that the arch specific variants are always preferred when
> available.
>
> 4. HARDLOCKUP_DETECTOR_PERF/BUDDY variables define whether the given
> detector is enabled in the end.
>
> 5. HAVE_HARDLOCKUP_DETECTOR_NON_ARCH and HARDLOCKUP_DETECTOR_NON_ARCH
> are temporary variables that are going to be removed in
> a followup patch.
>
> The patch just shuffles the definitions. It should not change the existing
> behavior.
>
> Signed-off-by: Petr Mladek <pmladek@suse.com>
> ---
> lib/Kconfig.debug | 112 +++++++++++++++++++++++-----------------------
> 1 file changed, 56 insertions(+), 56 deletions(-)

I don't really have any strong opinions, so I'm fine with this. In
general I think the ordering I picked tried to match the existing
"style" which generally tried to list configs and then select them
below. To me the existing style makes more sense when thinking about
writing C code without having to put a pile of prototypes at the top
of your file: you define things higher in the file and reference them
below. For instance, the old style (before any of my patches) had:

config SOFTLOCKUP_DETECTOR:
... blah blah blah ...

config HARDLOCKUP_DETECTOR_PERF:
select SOFTLOCKUP_DETECTOR

config HARDLOCKUP_DETECTOR:
... blah blah blah ...
select LOCKUP_DETECTOR
select HARDLOCKUP_DETECTOR_PERF if HAVE_HARDLOCKUP_DETECTOR_PERF

Your new style seems to be the opposite of that.

-Doug