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Date: Thu, 28 May 2009 14:53:11 +0200 (CEST)
From: Thomas Gleixner <tglx@linutronix.de>
To: Paul Mundt <lethal@linux-sh.org>
cc: Peter Zijlstra <peterz@infradead.org>, Daniel Walker <dwalker@fifo99.com>,
       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>
Subject: Re: [PATCH] sched: Support current clocksource handling in fallback
 sched_clock().
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On Thu, 28 May 2009, Paul Mundt wrote:

> On Thu, May 28, 2009 at 02:22:17PM +0200, Thomas Gleixner wrote:
> > On Thu, 28 May 2009, Paul Mundt wrote:
> > > @@ -437,10 +441,19 @@ void clocksource_unregister(struct clocksource *cs)
> > >  	unsigned long flags;
> > >  
> > >  	spin_lock_irqsave(&clocksource_lock, flags);
> > > +
> > > +	if (sched_clocksource == cs) {
> > > +		printk(KERN_WARNING "Refusing to unregister "
> > > +		       "scheduler clocksource %s", cs->name);
> > 
> >   Hmm, isn't that dangerous ? The clocksource might be in a module or
> >   in kmalloced memory which is going to be freed.
> > 
> Perhaps the saner thing to do is see if select_clocksource() manages to
> find something suitable, otherwise switch back to jiffies..

That makes sense. The scheduler should be able handle that, if not ... :)
 
Thanks,

	tglx