linux-kernel - Re: [tip:core/printk] ratelimit: Fix/allow use in atomic contexts

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Date:	Tue, 22 Sep 2009 07:46:19 -0700 (PDT)
From:	Linus Torvalds <torvalds@...ux-foundation.org>
To:	mingo@...hat.com, hpa@...or.com, linux-kernel@...r.kernel.org,
	a.p.zijlstra@...llo.nl, davem@...emloft.net,
	akpm@...ux-foundation.org, tglx@...utronix.de, mingo@...e.hu
cc:	linux-tip-commits@...r.kernel.org
Subject: Re: [tip:core/printk] ratelimit: Fix/allow use in atomic contexts




On Tue, 22 Sep 2009, tip-bot for Ingo Molnar wrote:
> 
> ratelimit: Fix/allow use in atomic contexts
> 
> I'd like to use printk_ratelimit() in NMI context, but it's not
> robust right now due to spinlock usage in lib/ratelimit.c. If an
> NMI is unlucky enough to hit just that spot we might lock up trying
> to take the spinlock again.
> 
> Fix that by using a trylock variant. If we contend on that lock we
> can genuinely skip the message because the state is just being
> accessed by another CPU (or by this CPU).

Ack to both this and the patch leading up to it. Looks sane and simple.

		Linus
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