linux-kernel - Re: [BUG/PATCH] x86 mmiotrace: dynamically disable non-boot CPUs

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Message-ID: <Pine.LNX.4.58.0804161506300.30154@gandalf.stny.rr.com>
Date:	Wed, 16 Apr 2008 15:07:25 -0400 (EDT)
From:	Steven Rostedt <rostedt@...dmis.org>
To:	Ingo Molnar <mingo@...e.hu>
cc:	Pekka Paalanen <pq@....fi>, linux-kernel@...r.kernel.org,
	vegard.nossum@...il.com, nouveau@...ts.freedesktop.org
Subject: Re: [BUG/PATCH] x86 mmiotrace: dynamically disable non-boot CPUs



On Wed, 16 Apr 2008, Ingo Molnar wrote:
>
> so lets fix those preemptability bugs. They show that the
> cpu-up/cpu-down ops are called from atomic context - it should normally
> be straightforward to sort out - there's no particular reason why the
> ->open()/->close() methods of an ftrace plugin should run in atomic
> context. Steve, any ideas where the atomicity might come from?
>

They shouldn't be called in an atomic section. The only thing I do to
protect them is call mutex_lock/unlock. Those should allow preemption to
take place.

-- Steve

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