linux-kernel - Re: [PATCH v3 08/15] kasan: add compiler barriers to KUNIT_EXPECT_KASAN

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Message-ID: <CAG_fn=VC=UPtVWfz81KeX+hEO1eC2PkZowWyFJbqz+jmiEeOQA@mail.gmail.com>
Date:   Fri, 15 Jan 2021 15:11:40 +0100
From:   Alexander Potapenko <glider@...gle.com>
To:     Andrey Konovalov <andreyknvl@...gle.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Catalin Marinas <catalin.marinas@....com>,
        Vincenzo Frascino <vincenzo.frascino@....com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Marco Elver <elver@...gle.com>,
        Will Deacon <will.deacon@....com>,
        Andrey Ryabinin <aryabinin@...tuozzo.com>,
        Peter Collingbourne <pcc@...gle.com>,
        Evgenii Stepanov <eugenis@...gle.com>,
        Branislav Rankov <Branislav.Rankov@....com>,
        Kevin Brodsky <kevin.brodsky@....com>,
        kasan-dev <kasan-dev@...glegroups.com>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        Linux Memory Management List <linux-mm@...ck.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 08/15] kasan: add compiler barriers to KUNIT_EXPECT_KASAN_FAIL

On Thu, Jan 14, 2021 at 8:36 PM Andrey Konovalov <andreyknvl@...gle.com> wrote:
>
> It might not be obvious to the compiler that the expression must be
> executed between writing and reading to fail_data. In this case, the
> compiler might reorder or optimize away some of the accesses, and
> the tests will fail.
>
> Add compiler barriers around the expression in KUNIT_EXPECT_KASAN_FAIL
> and use READ/WRITE_ONCE() for accessing fail_data fields.
>
> Link: https://linux-review.googlesource.com/id/I046079f48641a1d36fe627fc8827a9249102fd50
> Reviewed-by: Marco Elver <elver@...gle.com>
> Signed-off-by: Andrey Konovalov <andreyknvl@...gle.com>
Reviewed-by: Alexander Potapenko <glider@...gle.com>