linux-kernel - Re: [Linux-6.11-rc4] perf BROKEN with LLVM/Clang 19.1.0-rc3

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Message-ID: <CA+icZUUazXQVzf1AcuFSvT2FAL2Ag=xTFYxM35tvw8h-ix+rXA@mail.gmail.com>
Date: Fri, 23 Aug 2024 15:58:14 +0200
From: Sedat Dilek <sedat.dilek@...il.com>
To: Namhyung Kim <namhyung@...nel.org>
Cc: Arnaldo Carvalho de Melo <acme@...nel.org>, Peter Zijlstra <peterz@...radead.org>, 
	Ingo Molnar <mingo@...hat.com>, Ian Rogers <irogers@...gle.com>, linux-perf-users@...r.kernel.org, 
	linux-kernel@...r.kernel.org, Nathan Chancellor <nathan@...nel.org>
Subject: Re: [Linux-6.11-rc4] perf BROKEN with LLVM/Clang 19.1.0-rc3

On Thu, Aug 22, 2024 at 10:31 PM Namhyung Kim <namhyung@...nel.org> wrote:
>
> On Thu, Aug 22, 2024 at 1:26 PM Arnaldo Carvalho de Melo
> <acme@...nel.org> wrote:
> >
> > On Thu, Aug 22, 2024 at 01:11:22PM -0700, Namhyung Kim wrote:
> > > On Thu, Aug 22, 2024 at 11:20 AM Arnaldo Carvalho de Melo
> > > <acme@...nel.org> wrote:
> > > >
> > > > On Thu, Aug 22, 2024 at 11:17:21AM -0700, Namhyung Kim wrote:
> > > > > > On Thu, Aug 22, 2024 at 7:40 PM Arnaldo Carvalho de Melo
> > > > > > <acme@...nel.org> wrote:
> > > > > > > From 155212c965b5b23a90b8558449dbfd1c60dad934 Mon Sep 17 00:00:00 2001
> > > > > > > From: Arnaldo Carvalho de Melo <acme@...hat.com>
> > > > > > > Date: Thu, 22 Aug 2024 14:13:49 -0300
> > > > > > > Subject: [PATCH 1/1] perf python: Disable -Wno-cast-function-type-mismatch if
> > > > > > >  present on clang
> > > > > > >
> > > > > > > The -Wcast-function-type-mismatch option was introduced in clang 19 and
> > > > > > > its enabled by default, since we use -Werror, and python bindings do
> > > > > > > casts that are valid but trips this warning, disable it if present.
> > > > > > >
> > > > > > > Reported-by: Sedat Dilek <sedat.dilek@...il.com>
> > > > > > > Tested-by: Sedat Dilek <sedat.dilek@...il.com>
> > > > > > > Cc: Ian Rogers <irogers@...gle.com>
> > > > > > > Cc: Ingo Molnar <mingo@...hat.com>
> > > > > > > Cc: Namhyung Kim <namhyung@...nel.org>
> > > > > > > Cc: Nathan Chancellor <nathan@...nel.org>
> > > > > > > Cc: Peter Zijlstra <peterz@...radead.org>
> > > > > > > Link: https://lore.kernel.org/lkml/CA+icZUVtHn8X1Tb_Y__c-WswsO0K8U9uy3r2MzKXwTA5THtL7w@mail.gmail.com
> > > > > > > Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.com>
> > > > >
> > > > > Can we also add 'Fixes' tag to make this picked by stable kernels?
> > > >
> > > > Fixes what? This isn't a regression, clang 19 isn't available for Fedora
> > > > 40, the most recent.
> > >
> > > No, I'm not saying it's a bug.  But we may want to build the old
> > > source code using new clang.
> >
> > Sure, and with the tags we have now, we can signal it by using Closes:
> > and Cc: stable@...nel.org, without a version, I added those, the tags
> > section then is this:
> >
> >     Closes: https://lore.kernel.org/all/CA+icZUXoJ6BS3GMhJHV3aZWyb5Cz2haFneX0C5pUMUUhG-UVKQ@mail.gmail.com
> >     Reported-by: Sedat Dilek <sedat.dilek@...il.com>
> >     Tested-by: Sedat Dilek <sedat.dilek@...il.com>
> >     Cc: Ian Rogers <irogers@...gle.com>
> >     Cc: Ingo Molnar <mingo@...hat.com>
> >     Cc: Namhyung Kim <namhyung@...nel.org>
> >     Cc: Nathan Chancellor <nathan@...nel.org>
> >     Cc: Peter Zijlstra <peterz@...radead.org>
> >     Cc: stable@...r.kernel.org # To allow building with the upcoming clang 19
> >     Link: https://lore.kernel.org/lkml/CA+icZUVtHn8X1Tb_Y__c-WswsO0K8U9uy3r2MzKXwTA5THtL7w@mail.gmail.com
> >     Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.com>
> >
> > Ok?
>
> Acked-by: Namhyung Kim <namhyung@...nel.org>
>
> Thanks,
> Namhyung

Hey Namhyung,

are you aware of ...?

From: kernel test robot <lkp@...el.com>
To: oe-kbuild@...ts.linux.dev
Cc: lkp@...el.com
Subject: [perf-tools:tmp.perf-tools 1/1] error: command 'clang' failed
with exit code 1
Date: Fri, 23 Aug 2024 18:43:32 +0800 [thread overview]
Message-ID: <202408231822.dWGP67uY-lkp@...el.com> (raw)

https://lore.kernel.org/all/202408231822.dWGP67uY-lkp@intel.com/

That points to commit:

perf tools: Fix a build error with clang 19
https://git.kernel.org/pub/scm/linux/kernel/git/perf/perf-tools.git/commit/?h=tmp.perf-tools&id=cf36d63d7cc9a9770f69f44a10904e9fb0895fa9

That is fine with lLVM/Clang-19, but breaks previous versions like
LLVM-18 as explained in [1].

The REAL fixes are:

perf python: Allow checking for the existence of warning options in clang
https://git.kernel.org/pub/scm/linux/kernel/git/acme/linux.git/commit/?h=tmp.perf-tools-next&id=b81162302001f41157f6e93654aaccc30e817e2a

perf python: Disable -Wno-cast-function-type-mismatch if present on clang
https://git.kernel.org/pub/scm/linux/kernel/git/acme/linux.git/commit/?h=tmp.perf-tools-next&id=155212c965b5b23a90b8558449dbfd1c60dad934

Unsure if the commit-ids will change.

Do you happen to know how to feed the LKP-tests bot?

Best regards,
-Sedat-

[1] https://lore.kernel.org/all/CA+icZUVtHn8X1Tb_Y__c-WswsO0K8U9uy3r2MzKXwTA5THtL7w@mail.gmail.com/