Re: [PATCH] kbuild: unset sub_make_done before calling kselftest build system

[Petr Mladek]

On Fri 2026-07-03 11:32:30, Thomas Weißschuh wrote:
> On Fri, Jul 03, 2026 at 10:26:07AM +0200, Petr Mladek wrote:
> > On Fri 2026-07-03 06:14:48, sashiko-bot@xxxxxxxxxx wrote:
> > > Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
> > > - [Medium] Incomplete fix and inconsistent state: The patch correctly unsets `sub_make_done` for the `kselftest` targets to allow Kbuild command-line reevaluation when building external kernel modules. However, it fails to apply the same logic to the `tools/` and `tools/%` targets, introducing a discrepancy between build entry points.
> > > --
> > > 
> > > commit 06c418388d65deb3d8494a6e8e7071c0e709186b
> > > Author: Thomas Weißschuh <thomas.weissschuh@xxxxxxxxxxxxx>
> > > 
> > > kbuild: unset sub_make_done before calling kselftest build system
> > > 
> > > This commit unsets sub_make_done before invoking the kselftest build system to
> > > ensure Kbuild reevaluates command-line flags when building test modules. It
> > > mirrors a previous fix done for scripts/install.sh.
> > > 
> > > > diff --git a/Makefile b/Makefile
> > > > index b9c5792c79e01..f717a4dc96d6a 100644
> > > > --- a/Makefile
> > > > +++ b/Makefile
> > > > @@ -1591,10 +1591,10 @@ tools/%: FORCE
> > > >  
> > > >  PHONY += kselftest
> > > >  kselftest: headers
> > > > -	$(Q)$(MAKE) -C $(srctree)/tools/testing/selftests run_tests
> > > > +	$(Q)unset sub_make_done; $(MAKE) -C $(srctree)/tools/testing/selftests run_tests
> > > 
> > > [Severity: Medium]
> > > Will make tools/selftests still fail after this change?
> > > 
> > > The tools/ and tools/% targets in Makefile delegate to the tools build
> > > system, which can also trigger external kernel module builds (like bpf_testmod).
> > > 
> > > Because sub_make_done is not unset for these targets, invoking commands like
> > > make tools/selftests or make tools/all will skip Kbuild's M= argument parsing.
> > > 
> > > Should sub_make_done also be unset in the tools/ and tools/% targets to maintain
> > > consistency across the build entry points?
> > 
> > This might make sense. I see that the tools: and tools/%: targets are
> > defined right above the kselftest*: ones. And they are even advertised
> > in "make help" or "make tools/help".
> 
> I am not sure how the tools/ targets can reach back into kbuild.
> The example with bpf_testmod above is bogus, as tools/* is only for
> top-level tools directories. Subdirectories in tools/testing/selftests/
> don't seem to be reachable.

I see.

> > Well it probably should be done in a separate patch. It would be better
> > for bisecting potential regressions. Thomas, Zelin, what do you think, please?
> 
> If we do it for consistency it should be its own patch, agreed.

I would keep it as is until anyone reports a real problem.

Thanks a lot for explanation.

Best Regards,
Petr