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From: Namhyung Kim <namhyung@kernel.org>
To: Frederic Weisbecker <fweisbec@gmail.com>
Cc: LKML <linux-kernel@vger.kernel.org>,
        Alessio Igor Bogani <abogani@kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Chris Metcalf <cmetcalf@tilera.com>, Christoph Lameter <cl@linux.com>,
        Geoff Levand <geoff@infradead.org>,
        Gilad Ben Yossef <gilad@benyossef.com>,
        Hakan Akkan <hakanakkan@gmail.com>, Ingo Molnar <mingo@kernel.org>,
        "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
        Paul Gortmaker <paul.gortmaker@windriver.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Steven Rostedt <rostedt@goodmis.org>,
        Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH 21/27] nohz: Only stop the tick on RCU nocb CPUs
References: <1356799386-4212-1-git-send-email-fweisbec@gmail.com>
	<1356799386-4212-22-git-send-email-fweisbec@gmail.com>
Date: Wed, 02 Jan 2013 17:47:33 +0900
In-Reply-To: <1356799386-4212-22-git-send-email-fweisbec@gmail.com> (Frederic
	Weisbecker's message of "Sat, 29 Dec 2012 17:43:00 +0100")
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Hi Frederic,

On Sat, 29 Dec 2012 17:43:00 +0100, Frederic Weisbecker wrote:
> On a full dynticks CPU, we want the RCU callbacks to be
> offlined to another CPU, otherwise we need to keep
> the tick to wait for the grace period completion.
>
> Ensure the full dynticks CPU is also an rcu_nocb one.
[snip]
> -static bool is_nocb_cpu(int cpu)
> -{
> -	return false;
> -}
> -

You may want to add the following also to shut up the gcc:

      CC      kernel/rcutree.o
    In file included from /home/namhyung/project/linux/kernel/rcutree.c:58:0:
    /home/namhyung/project/linux/kernel/rcutree.h:539:13: warning: ‘is_nocb_cpu’ declared ‘static’ but never defined [-Wunused-function]


Thanks,
Namhyung


diff --git a/kernel/rcutree.h b/kernel/rcutree.h
index 4b69291b093d..fbbad931c36a 100644
--- a/kernel/rcutree.h
+++ b/kernel/rcutree.h
@@ -536,7 +536,6 @@ static void print_cpu_stall_info(struct rcu_state *rsp, int cpu);
 static void print_cpu_stall_info_end(void);
 static void zero_cpu_stall_ticks(struct rcu_data *rdp);
 static void increment_cpu_stall_ticks(void);
-static bool is_nocb_cpu(int cpu);
 static bool __call_rcu_nocb(struct rcu_data *rdp, struct rcu_head *rhp,
                            bool lazy);
 static bool rcu_nocb_adopt_orphan_cbs(struct rcu_state *rsp,