From mboxrd@z Thu Jan  1 00:00:00 1970
From: Peter Zijlstra <peterz@infradead.org>
Date: Thu, 28 May 2009 16:32:09 +0000
Subject: Re: [PATCH] sched: Support current clocksource handling in
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To: Daniel Walker <dwalker@fifo99.com>
Cc: Paul Mundt <lethal@linux-sh.org>, Thomas Gleixner <tglx@linutronix.de>, Linus Walleij <linus.ml.walleij@gmail.com>, Ingo Molnar <mingo@elte.hu>, Andrew Victor <linux@maxim.org.za>, Haavard Skinnemoen <hskinnemoen@atmel.com>, Andrew Morton <akpm@linux-foundation.org>, linux-kernel@vger.kernel.org, linux-sh@vger.kernel.org, linux-arm-kernel@lists.arm.linux.org.uk, John Stultz <johnstul@linux.vnet.ibm.com>

On Thu, 2009-05-28 at 09:13 -0700, Daniel Walker wrote:
> On Thu, 2009-05-28 at 14:59 +0200, Peter Zijlstra wrote:
> 
> > 
> > 
> > CPU0                           CPU1
> > 
> > clock = ACCESS_ONCE(sched_clocksource);
> > 
> >                                unload module
> >                                  clocksource_unregister()
> >                                    sched_clocksource = jiffies
> >                                  unmap data/text
> > 
> > cyc2ns(clock, clocksource_read(clock)) <--- fireworks
> > 
> > 
> 
> Do any module based clocksources even exist right now?
> clocksource_unregister only seems to be used 3 times..

Good point, it appears its not even exported.

Thomas mentioned modules, I assumed.