From mboxrd@z Thu Jan  1 00:00:00 1970
From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Subject: Re: [PATCH RFC idle 2/3] arm: Avoid invoking RCU when CPU is idle
Date: Thu, 2 Feb 2012 15:27:36 -0800
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To: Steven Rostedt <rostedt@goodmis.org>
Cc: Nicolas Pitre <nicolas.pitre@linaro.org>, mathieu.desnoyers@polymtl.ca, peterz@infradead.org, fweisbec@gmail.com, Nicolas Ferre <nicolas.ferre@atmel.com>, dhowells@redhat.com, Lennert Buytenhek <kernel@wantstofly.org>, Kevin Hilman <khilman@ti.com>, Kukjin Kim <kgene.kim@samsung.com>, Russell King <linux@arm.linux.org.uk>, eric.dumazet@gmail.com, "Paul E. McKenney" <paul.mckenney@linaro.org>, Magnus Damm <magnus.damm@gmail.com>, Tony Lindgren <tony@atomide.com>, dipankar@in.ibm.com, darren@dvhart.com, mingo@elte.hu, Jean-Christophe Plagniol-Villard <plagnioj@jcrosoft.com>, Len Brown <len.brown@intel.com>, Amit Kucheria <amit.kucheria@canonical.com>, patches@linaro.org, Will Deacon <will.deacon@arm.com>, josh@joshtriplett.org, Sekhar Nori <nsekhar@ti.com>, niv@us.ibm.com, linux-samsung-soc@vger.kernel.org, Barry Song <baohua.song@csr.com>, tglx@linutronix.de, linux-omap@v
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On Thu, Feb 02, 2012 at 06:03:39PM -0500, Steven Rostedt wrote:

[ . . . ]

> Anyway, one answer is (and I was talking with Paul about this on IRC) is
> that we can create a special "TRACE_EVENT_IDLE()" that will explicitly
> call "rcu_idle_exit/enter()" as it expects to be called with it off.
> 
> This should solve most issues I believe.

You OK with something like RCU_NONIDLE() rather than RCU_EVENT_IDLE()?
I have this funny feeling that tracing won't be the only thing using
RCU from idle.  :-/

Something like this, perhaps?

	#define RCU_NONIDLE(a) \
		do { \
			rcu_idle_exit(); \
			do { a; } while (0); \
			rcu_idle_enter(); \
		}

							Thanx, Paul