linux-kernel - Re: [PATCH v2 10/20] kasan: inline and rename kasan_unpoison

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Date:   Thu, 12 Nov 2020 20:45:18 +0100
From:   Andrey Konovalov <andreyknvl@...gle.com>
To:     Marco Elver <elver@...gle.com>
Cc:     Dmitry Vyukov <dvyukov@...gle.com>,
        Alexander Potapenko <glider@...gle.com>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will.deacon@....com>,
        Vincenzo Frascino <vincenzo.frascino@....com>,
        Evgenii Stepanov <eugenis@...gle.com>,
        Andrey Ryabinin <aryabinin@...tuozzo.com>,
        Branislav Rankov <Branislav.Rankov@....com>,
        Kevin Brodsky <kevin.brodsky@....com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        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 v2 10/20] kasan: inline and rename kasan_unpoison_memory

On Wed, Nov 11, 2020 at 6:49 PM Marco Elver <elver@...gle.com> wrote:
>
> On Tue, Nov 10, 2020 at 11:20PM +0100, Andrey Konovalov wrote:
> > Currently kasan_unpoison_memory() is used as both an external annotation
> > and as an internal memory poisoning helper. Rename external annotation to
> > kasan_unpoison_data() and inline the internal helper for hardware
> > tag-based mode to avoid undeeded function calls.
>
> I don't understand why this needs to be renamed again. The users of
> kasan_unpoison_memory() outweigh those of kasan_unpoison_slab(), of
> which there seems to be only 1!

The idea is to make kasan_(un)poison_memory() functions inlinable for
internal use. It doesn't have anything to do with the number of times
they are used.

Perhaps we can drop the kasan_ prefix for the internal implementations
though, and keep using kasan_unpoison_memory() externally.

> So can't we just get rid of kasan_unpoison_slab() and just open-code it
> in mm/mempool.c:kasan_unpoison_element()? That function is already
> kasan-prefixed, so we can even place a small comment there (which would
> also be an improvement over current interface, since
> kasan_unpoison_slab() is not documented and its existence not quite
> justified).

We can, but this is a change unrelated to this patch.