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Date: Tue, 16 Oct 2012 00:08:48 -0400
From: "Theodore Ts'o" <tytso@mit.edu>
To: "H. Peter Anvin" <hpa@zytor.com>
Cc: "H. Peter Anvin" <hpa@linux.intel.com>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
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        DJ Johnston <dj.johnston@intel.com>, stable@vger.kernel.org
Subject: Re: [PATCH RFC] random: Account for entropy loss due to overwrites
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On Sat, Sep 29, 2012 at 12:47:04PM -0700, H. Peter Anvin wrote:
> >-static struct poolinfo {
> >+static const struct poolinfo {
> >+	int poolshift;		/* log2(POOLBITS) */
> >  	int poolwords;
> >  	int tap1, tap2, tap3, tap4, tap5;

Poolshift is duplicated information; it's just log2(poolwords) + 5
(since POOLBITS is poolwords*32).

Granted you don't want to recalculate it every single time you need to
use it, but perhaps it would be better to add poolshift to struct
entropy_store, and set it in init_std_data()?

				- Ted
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