Date: Thu, 9 Aug 2007 19:00:40 -0700
From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: Adrian Bunk <bunk@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>, Josh Triplett <josh@kernel.org>,
       linux-kernel@vger.kernel.org
Subject: Re: 2.6.23-rc2-mm1: rcutorture xtime usage
Message-ID: <20070810020040.GK8424@linux.vnet.ibm.com>
Reply-To: paulmck@linux.vnet.ibm.com
References: <20070809015106.cd0bfc53.akpm@linux-foundation.org> <20070810013146.GD18938@stusta.de>
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On Fri, Aug 10, 2007 at 03:31:46AM +0200, Adrian Bunk wrote:
> On Thu, Aug 09, 2007 at 01:51:06AM -0700, Andrew Morton wrote:
> >...
> > Changes since 2.6.23-rc2-mm1:
> >...
> > +allow-rcutorture-to-handle-synchronize_sched.patch
> >...
> >  2.6.23 queue
> >...
> 
> All drivers were converted to no longer use xtime directly since it 
> might be quite outdated, but this patch adds a usage of xtime.tv_nsec
> as RNG...

This code doesn't care if the time is outdated, as it is simply
periodically perturbing an RNG, but OK.

So, what interface are we supposed to be using instead?  I cannot use
get_random_bytes() due to locking issues.  This is not a cryptographically
secure usage, so the perturbation does not need to be extremely high
quality.

On x86, I would just grab the low-order bits of the TSC, but all of the
world is not an x86.  ;-)

							Thanx, Paul
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