linux-kernel - Re: [PATCH] mm/kfence: select random number before taking raw lock

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Message-ID: <CAHmME9rkQDnsTu-8whevtBa_J6aOKT=gQO7kBAxwWrBgKgcyUQ@mail.gmail.com>
Date:   Thu, 9 Jun 2022 14:29:37 +0200
From:   "Jason A. Donenfeld" <Jason@...c4.com>
To:     Marco Elver <elver@...gle.com>
Cc:     Linux-MM <linux-mm@...ck.org>, LKML <linux-kernel@...r.kernel.org>,
        John Ogness <john.ogness@...utronix.de>,
        Alexander Potapenko <glider@...gle.com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Geert Uytterhoeven <geert@...ux-m68k.org>
Subject: Re: [PATCH] mm/kfence: select random number before taking raw lock

On Thu, Jun 9, 2022 at 2:27 PM Marco Elver <elver@...gle.com> wrote:
> The compiler should elide this branch entirely if
> CONFIG_KFENCE_STRESS_TEST_FAULTS=0, but not sure it'll always do so
> now. My suggestion is to make both new bools consts, to help out the
> compiler a little.
>
> Otherwise looks good, thanks for the quick fix!

Disassembling reveals it still does elide. (gcc 11.3) But I'll make
them const just in case and send a v2.

Jason