linux-kernel - Re: [debug patch] printk: Add a printk killswitch to robustify NMI watchdog messages

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Date:	Wed, 8 Jun 2011 22:54:08 +0200 (CEST)
From:	Thomas Gleixner <tglx@...utronix.de>
To:	Peter Zijlstra <peterz@...radead.org>
cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Ingo Molnar <mingo@...e.hu>,
	Arne Jansen <lists@...-jansens.de>, mingo@...hat.com,
	hpa@...or.com, linux-kernel@...r.kernel.org, efault@....de,
	npiggin@...nel.dk, akpm@...ux-foundation.org,
	frank.rowand@...sony.com, linux-tip-commits@...r.kernel.org
Subject: Re: [debug patch] printk: Add a printk killswitch to robustify NMI
 watchdog messages

On Wed, 8 Jun 2011, Peter Zijlstra wrote:

> On Wed, 2011-06-08 at 12:27 -0700, Linus Torvalds wrote:
> > Make some kind of
> > 
> >   void atomic_down();
> >   int atomic_down_trylock();
> >   void atomic_up(); 
> 
> atomic_down() is a tad iffy, it would have to wait for an actual
> semaphore owner, which might sleep etc.. So I skipped it.
> 
> The other two are implemented here, and assume IRQs are disabled, we
> could add _irq and _irqsave versions of both, but since there are no
> users I avoided the effort.
> 
> ---
>  include/linux/semaphore.h |    3 +++
>  kernel/semaphore.c        |   36 +++++++++++++++++++++++++++++++++++-

Can we please confine this to kernel/printk.c ?

I can see the creative abuse of this already.

Thanks,

	tglx
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