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From:   Marco Elver <elver@google.com>
Date:   Thu, 21 May 2020 15:42:12 +0200
Message-ID: <CANpmjNMf7JRG4P1Ab2qsCy4Yw6vw2WC7yCgqUSBBOsBQdc_5bQ@mail.gmail.com>
Subject: Re: [PATCH -tip v2 00/11] Fix KCSAN for new ONCE (require Clang 11)
To:     Will Deacon <will@kernel.org>
Cc:     "Paul E. McKenney" <paulmck@kernel.org>,
        Dmitry Vyukov <dvyukov@google.com>,
        Alexander Potapenko <glider@google.com>,
        Andrey Konovalov <andreyknvl@google.com>,
        kasan-dev <kasan-dev@googlegroups.com>,
        LKML <linux-kernel@vger.kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@kernel.org>,
        Peter Zijlstra <peterz@infradead.org>,
        clang-built-linux <clang-built-linux@googlegroups.com>,
        Borislav Petkov <bp@alien8.de>
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On Thu, 21 May 2020 at 15:36, Will Deacon <will@kernel.org> wrote:
>
> On Thu, May 21, 2020 at 01:08:43PM +0200, Marco Elver wrote:
> > This patch series is the conclusion to [1], where we determined that due
> > to various interactions with no_sanitize attributes and the new
> > {READ,WRITE}_ONCE(), KCSAN will require Clang 11 or later. Other
> > sanitizers are largely untouched, and only KCSAN now has a hard
> > dependency on Clang 11. To test, a recent Clang development version will
> > suffice [2]. While a little inconvenient for now, it is hoped that in
> > future we may be able to fix GCC and re-enable GCC support.
> >
> > The patch "kcsan: Restrict supported compilers" contains a detailed list
> > of requirements that led to this decision.
> >
> > Most of the patches are related to KCSAN, however, the first patch also
> > includes an UBSAN related fix and is a dependency for the remaining
> > ones. The last 2 patches clean up the attributes by moving them to the
> > right place, and fix KASAN's way of defining __no_kasan_or_inline,
> > making it consistent with KCSAN.
> >
> > The series has been tested by running kcsan-test several times and
> > completed successfully.
>
> I've left a few minor comments, but the only one that probably needs a bit
> of thought is using data_race() with const non-scalar expressions, since I
> think that's now prohibited by these changes. We don't have too many
> data_race() users yet, so probably not a big deal, but worth bearing in
> mind.

If you don't mind, I'll do a v3 with that fixed.

> Other than that,
>
> Acked-by: Will Deacon <will@kernel.org>

Thank you!

-- Marco

> Thanks!
>
> Will