Re: [PATCH 1/1 fyi] tools headers UAPI: Sync linux/prctl.h with the kernel sources to pick FUTEX knob

[Arnaldo Carvalho de Melo]

On Wed, Jun 11, 2025 at 10:43:26AM +0200, Sebastian Andrzej Siewior wrote:
> On 2025-06-10 17:40:26 [-0300], Arnaldo Carvalho de Melo wrote:
> > tldr; Just FYI, I'm carrying this on the perf tools tree.
> 
> Thank you.
> 
> >   $ tools/perf/trace/beauty/prctl_option.sh > before
> >   $ cp include/uapi/linux/prctl.h tools/perf/trace/beauty/include/uapi/linux/prctl.h
> >   $ tools/perf/trace/beauty/prctl_option.sh > after
> 
> Ah. I missed that copy of prctl.h
> 
> …
> > This addresses this perf build warning:
> > 
> >   Warning: Kernel ABI header differences:
> >     diff -u tools/include/uapi/linux/prctl.h include/uapi/linux/prctl.h
> 
> But I did cover this one.

I fixed up the warning message being addressed, the attempt was at
having what used in perf just in
tools/perf/trace/beauty/include/uapi/linux/prctl.h, i.e. just for
scrapping, not for building things with it.

But then:

commit c142850fbc956058ff2f2987d3d11eb2c628f710
Author: John Hubbard <jhubbard@xxxxxxxxxx>
Date:   Mon Jun 17 19:24:21 2024 -0700

    selftests/mm: kvm, mdwe fixes to avoid requiring "make headers"

this adds another copy there.

I think we should then remove the
tools/perf/trace/beauty/include/uapi/linux/prctl.h one and make
tools/perf/check_headers.sh to go back to check
tools/include/uapi/linux/prctl.h.

But then, as mentioned in tools/include/uapi/README, its better for
people updating the kernel original files not to update the copy, as it
may break tools/ code if it, for instance, starts including some other
header, etc.

tools people should notice the warning from tools/perf/check_headers.sh
(that now probably should be moved to tools/ as these copies are not
used just by perf...) and check how to update it.

- Arnaldo