Date: Sun, 22 Jan 2012 22:55:46 +0400 From: Andrey Chernov <ache@FreeBSD.ORG> To: Mark Murray <markm@FreeBSD.ORG> Cc: svn-src-head@FreeBSD.ORG, David Schultz <das@FreeBSD.ORG>, src-committers@FreeBSD.ORG, svn-src-all@FreeBSD.ORG Subject: Re: svn commit: r230230 - head/sys/dev/random Message-ID: <20120122185545.GA11874@vniz.net> In-Reply-To: <E1Rp0lq-000Gly-FT@groundzero.grondar.org> References: <201201162018.q0GKIADK050161@svn.freebsd.org> <20120118061943.GA80874@vniz.net> <E1Rny2A-000C3x-O6@groundzero.grondar.org> <20120120055823.GA28177@vniz.net> <E1RoG98-000DiP-0Y@groundzero.grondar.org> <20120120215649.GA40016@vniz.net> <E1Rp0lq-000Gly-FT@groundzero.grondar.org>
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On Sun, Jan 22, 2012 at 04:59:55PM +0000, Mark Murray wrote:
> Andrey Chernov writes:
> > > The usual way round this is with a flag. Set a static, volatile
> > > flag, defaulting "off", and set it to "on" when the seeding has
> > > happened. Then arc4random() can do the right thing, depending on
> > > this flag.
> >
> > Ok, what about this version, is it right? libkern/arc4rand.c is not a
> > module but always present in the kernel, so "arc4rand_iniseed_state"
> > will be always accessible.
> >
> > --- dev/random/randomdev_soft.c.old 2011-09-26 07:35:48.000000000 +0400
> > +++ dev/random/randomdev_soft.c 2012-01-21 01:41:37.000000000 +0400
> > @@ -55,6 +55,8 @@ __FBSDID("$FreeBSD: src/sys/dev/random/r
> >
> > #define RANDOM_FIFO_MAX 256 /* How many events to queue up */
> >
> > +extern int arc4rand_iniseed_state;
> > +
>
> Should be in a header file, nad _possibly_ should be volatile. If it
> works without being volatile, then OK.
It was preliminary patch just to confirm/deny my understanding of your
idea.
I'll put it into header.
In the final version I also plan to move that lines
+ if (arc4rand_iniseed_state == 1)
+ arc4rand_iniseed_state = -1;
into arc4_randomstir() where they will be protected with mutex lock, so
volatile will be not needed. It will be more logical, because other
reseeding conditions are resetted there too.
> The rest is OK. I've not tested it, so this is not a review, simply an
> "OK" :-)
Thanx for review! I'll send final version to this thread a bit
later when I'll find more free time.
--
http://ache.vniz.net/
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