linux-kernel - Re: [PATCH v5 10/11] xtensa: use fallback for random_get

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Message-ID: <CAMo8Bf+ox2MQRkqsTaOOXOchOWpb+7P8GQ1c-TjwSpDgttXoFA@mail.gmail.com>
Date:   Thu, 21 Apr 2022 01:00:36 -0700
From:   Max Filippov <jcmvbkbc@...il.com>
To:     "Jason A. Donenfeld" <Jason@...c4.com>
Cc:     LKML <linux-kernel@...r.kernel.org>, linux-crypto@...r.kernel.org,
        Thomas Gleixner <tglx@...utronix.de>,
        Arnd Bergmann <arnd@...db.de>, "Theodore Ts'o" <tytso@....edu>,
        Dominik Brodowski <linux@...inikbrodowski.net>,
        Russell King <linux@...linux.org.uk>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        "David S . Miller" <davem@...emloft.net>,
        Richard Weinberger <richard@....at>,
        Anton Ivanov <anton.ivanov@...bridgegreys.com>,
        Johannes Berg <johannes@...solutions.net>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        "H . Peter Anvin" <hpa@...or.com>, Chris Zankel <chris@...kel.net>,
        Stephen Boyd <sboyd@...nel.org>,
        Dinh Nguyen <dinguyen@...nel.org>,
        linux-arm-kernel@...ts.infradead.org,
        "open list:M68K ARCHITECTURE" <linux-m68k@...ts.linux-m68k.org>,
        linux-mips@...r.kernel.org,
        linux-riscv <linux-riscv@...ts.infradead.org>,
        "open list:SPARC + UltraSPAR..." <sparclinux@...r.kernel.org>,
        linux-um@...ts.infradead.org,
        "maintainer:X86 ARCHITECTURE..." <x86@...nel.org>,
        "open list:TENSILICA XTENSA PORT (xtensa)" 
        <linux-xtensa@...ux-xtensa.org>
Subject: Re: [PATCH v5 10/11] xtensa: use fallback for random_get_entropy()
 instead of zero

On Tue, Apr 19, 2022 at 4:18 AM Jason A. Donenfeld <Jason@...c4.com> wrote:
>
> In the event that random_get_entropy() can't access a cycle counter or
> similar, falling back to returning 0 is really not the best we can do.
> Instead, at least calling random_get_entropy_fallback() would be
> preferable, because that always needs to return _something_, even
> falling back to jiffies eventually. It's not as though
> random_get_entropy_fallback() is super high precision or guaranteed to
> be entropic, but basically anything that's not zero all the time is
> better than returning zero all the time.
>
> This is accomplished by just including the asm-generic code like on
> other architectures, which means we can get rid of the empty stub
> function here.
>
> Cc: Thomas Gleixner <tglx@...utronix.de>
> Cc: Arnd Bergmann <arnd@...db.de>
> Cc: Max Filippov <jcmvbkbc@...il.com>
> Signed-off-by: Jason A. Donenfeld <Jason@...c4.com>
> ---
>  arch/xtensa/include/asm/timex.h | 6 ++----
>  1 file changed, 2 insertions(+), 4 deletions(-)

Acked-by: Max Filippov <jcmvbkbc@...il.com>

-- 
Thanks.
-- Max