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From:   "Jason A. Donenfeld" <Jason@zx2c4.com>
Date:   Tue, 12 Apr 2022 00:07:58 +0200
Message-ID: <CAHmME9qU7x3=KsjfH0qDW=isdcGxTweHbssvshYxkV5iHpamGw@mail.gmail.com>
Subject: Re: [PATCH v2 03/11] m68k: use ktime_read_raw_clock() for
 random_get_entropy() instead of zero
To:     Thomas Gleixner <tglx@linutronix.de>
Cc:     LKML <linux-kernel@vger.kernel.org>,
        Linux Crypto Mailing List <linux-crypto@vger.kernel.org>,
        Arnd Bergmann <arnd@arndb.de>, "Theodore Ts'o" <tytso@mit.edu>,
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        Russell King <linux@armlinux.org.uk>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Will Deacon <will@kernel.org>,
        Geert Uytterhoeven <geert@linux-m68k.org>,
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Hi Thomas,

On Mon, Apr 11, 2022 at 10:18 AM Thomas Gleixner <tglx@linutronix.de> wrote:
> > diff --git a/arch/m68k/include/asm/timex.h b/arch/m68k/include/asm/timex.h
> > index 6a21d9358280..5351b10e1b18 100644
> > --- a/arch/m68k/include/asm/timex.h
> > +++ b/arch/m68k/include/asm/timex.h
> > @@ -35,7 +35,7 @@ static inline unsigned long random_get_entropy(void)
> >  {
> >       if (mach_random_get_entropy)
> >               return mach_random_get_entropy();
> > -     return 0;
> > +     return ktime_read_raw_clock();
>
> I'd rather do something like this in a common header:
>
> unsigned long random_get_entropy_fallback(void);
>
> and use random_get_entropy_fallback() in the architecture specific
> files.
>
> That way you can encapsulate the fallback implementation in the random
> code and if it turns out that ktime_read_raw_clock() is a stupid idea or
> someone has a better idea then you have to change exactly one place and
> not patch the whole tree again.

Absolutely. That's a good idea. I'll do that for v3.

Jason