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

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Message-ID: <BANLkTimPXSVSrCWQq5Jy_RWMoqg1GJYLdQ@mail.gmail.com>
Date:	Wed, 8 Jun 2011 13:53:48 -0700
From:	Linus Torvalds <torvalds@...ux-foundation.org>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	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, tglx@...utronix.de,
	linux-tip-commits@...r.kernel.org
Subject: Re: [debug patch] printk: Add a printk killswitch to robustify NMI
 watchdog messages

On Wed, Jun 8, 2011 at 1:32 PM, Peter Zijlstra <peterz@...radead.org> wrote:
>
> atomic_down() is a tad iffy, it would have to wait for an actual
> semaphore owner, which might sleep etc.. So I skipped it.

I think sleeping would be fine: the "atomic" part is about the code
the semaphore protects, not about the down() itself.

But the way you made the semantics be (caller has to disable
interrupts) for the other helpers, that doesn't really work.

                               Linus
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