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From:   Andrey Konovalov <andreyknvl@google.com>
Date:   Mon, 11 Jan 2021 20:03:29 +0100
Message-ID: <CAAeHK+y8B9x2av0C3kj_nFEjgHmkxu1Y=5Y3U4-HzxWgTMh1uQ@mail.gmail.com>
Subject: Re: [PATCH v3] kasan: remove redundant config option
To:     Nathan Chancellor <natechancellor@gmail.com>
Cc:     Walter Wu <walter-zh.wu@mediatek.com>,
        Andrey Ryabinin <aryabinin@virtuozzo.com>,
        Alexander Potapenko <glider@google.com>,
        Dmitry Vyukov <dvyukov@google.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        kasan-dev <kasan-dev@googlegroups.com>,
        Linux Memory Management List <linux-mm@kvack.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Linux ARM <linux-arm-kernel@lists.infradead.org>,
        wsd_upstream <wsd_upstream@mediatek.com>,
        "moderated list:ARM/Mediatek SoC..." 
        <linux-mediatek@lists.infradead.org>
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On Mon, Jan 11, 2021 at 7:59 PM Nathan Chancellor
<natechancellor@gmail.com> wrote:
>
> > > -config KASAN_STACK_ENABLE
> > > +config KASAN_STACK
> > >         bool "Enable stack instrumentation (unsafe)" if CC_IS_CLANG && !COMPILE_TEST
> >
> > Does this syntax mean that KASAN_STACK is only present for
> > CC_IS_CLANG? Or that it can only be disabled for CC_IS_CLANG?
>
> It means that the option can only be disabled for clang.

OK, got it.

> > Anyway, I think it's better to 1. allow to control KASAN_STACK
> > regardless of the compiler (as it was possible before), and 2. avoid
>
> It has never been possible to control KASAN_STACK for GCC because of the
> bool ... if ... syntax. This patch does not change that logic. Making it
> possible to control KASAN_STACK with GCC seems fine but that is going to
> be a new change that would probably be suited for a new patch on top of
> this one.

The if syntax was never applied to KASAN_STACK, only to
KASAN_STACK_ENABLE, so it should have been possible (although I've
never specifically tried it).