linux-kernel - Re: [PATCH] /dev/random: Insufficient of entropy on many architectures

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Message-ID: <CAMuHMdWMiD1kw34CUJ-KCbk4mKggjtMzxVPpkN=ddfaq_vs9sg@mail.gmail.com>
Date:	Thu, 12 Sep 2013 13:59:04 +0200
From:	Geert Uytterhoeven <geert@...ux-m68k.org>
To:	Stephan Mueller <smueller@...onox.de>
Cc:	"Theodore Ts'o" <tytso@....edu>,
	LKML <linux-kernel@...r.kernel.org>, dave.taht@...ferbloat.net
Subject: Re: [PATCH] /dev/random: Insufficient of entropy on many architectures

On Wed, Sep 11, 2013 at 8:49 AM, Stephan Mueller <smueller@...onox.de> wrote:
> __u64 tmp = random_get_fast_cycles() - random_get_fast_cycles();
> if(0 == tmp)
>         return fail;
> return pass;

That will fail if the cycle counter runs at less than say 4 times the
CPU clock...

BTW, I prefer a different name than "random_get_fast_cycles()", as it's better
to have something that returns different and unpredictable numbers than an
actual monotonic cycle counter.

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds
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