linux-kernel - Re: [PATCH -tip v2 00/11] Fix KCSAN for new ONCE (require Clang 11)

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Date:   Thu, 21 May 2020 14:42:58 +0100
From:   Will Deacon <will@...nel.org>
To:     Marco Elver <elver@...gle.com>
Cc:     "Paul E. McKenney" <paulmck@...nel.org>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Alexander Potapenko <glider@...gle.com>,
        Andrey Konovalov <andreyknvl@...gle.com>,
        kasan-dev <kasan-dev@...glegroups.com>,
        LKML <linux-kernel@...r.kernel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        clang-built-linux <clang-built-linux@...glegroups.com>,
        Borislav Petkov <bp@...en8.de>
Subject: Re: [PATCH -tip v2 00/11] Fix KCSAN for new ONCE (require Clang 11)

On Thu, May 21, 2020 at 03:42:12PM +0200, Marco Elver wrote:
> On Thu, 21 May 2020 at 15:36, Will Deacon <will@...nel.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.

Works for me, thanks.

Will