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Date: Thu, 2 Feb 2012 02:54:30 +0100
From: Frederic Weisbecker <fweisbec@...il.com>
To: "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
Cc: linux-kernel@...r.kernel.org, mingo@...e.hu, laijs@...fujitsu.com,
dipankar@...ibm.com, akpm@...ux-foundation.org,
mathieu.desnoyers@...ymtl.ca, josh@...htriplett.org,
niv@...ibm.com, tglx@...utronix.de, peterz@...radead.org,
rostedt@...dmis.org, Valdis.Kletnieks@...edu, dhowells@...hat.com,
eric.dumazet@...il.com, darren@...art.com, patches@...aro.org,
"Paul E. McKenney" <paul.mckenney@...aro.org>,
"H. Peter Anvin" <hpa@...or.com>, Len Brown <lenb@...nel.org>,
Borislav Petkov <bp@...en8.de>,
Kamalesh Babulal <kamalesh@...ux.vnet.ibm.com>,
Stephen Wilson <wilsons@...rt.ca>, linux-pm@...r.kernel.org,
x86@...nel.org
Subject: Re: [PATCH RFC idle 1/3] x86: Avoid invoking RCU when CPU is idle
On Wed, Feb 01, 2012 at 04:43:22PM -0800, Paul E. McKenney wrote:
> From: "Paul E. McKenney" <paul.mckenney@...aro.org>
>
> The idle loop is a quiscent state for RCU, which means that RCU ignores
> CPUs that have told RCU that they are idle via rcu_idle_enter(). There
> are nevertheless quite a few places where idle CPUs use RCU, most commonly
> indirectly via tracing. This patch fixes these problems for x86.
>
> Many of these bugs have been in the kernel for quite some time, but
> Frederic's recent change now gives warnings.
>
> This patch takes the straightforward approach of pushing the
> rcu_idle_enter()/rcu_idle_exit() pair further down into the core
> of the idle loop.
I guess this is about the trace_power_*() things, right?
Acked-by: Frederic Weisbecker <fweisbec@...il.com>
Thanks.
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