linux-kernel - [PATCH 34/45] hexagon/smp: Use get/put_online_cpus

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Message-ID: <20130623134545.19094.46020.stgit@srivatsabhat.in.ibm.com>
Date:	Sun, 23 Jun 2013 19:15:49 +0530
From:	"Srivatsa S. Bhat" <srivatsa.bhat@...ux.vnet.ibm.com>
To:	tglx@...utronix.de, peterz@...radead.org, tj@...nel.org,
	oleg@...hat.com, paulmck@...ux.vnet.ibm.com, rusty@...tcorp.com.au,
	mingo@...nel.org, akpm@...ux-foundation.org, namhyung@...nel.org,
	walken@...gle.com, vincent.guittot@...aro.org, laijs@...fujitsu.com
Cc:	rostedt@...dmis.org, wangyun@...ux.vnet.ibm.com,
	xiaoguangrong@...ux.vnet.ibm.com, sbw@....edu, fweisbec@...il.com,
	zhong@...ux.vnet.ibm.com, nikunj@...ux.vnet.ibm.com,
	srivatsa.bhat@...ux.vnet.ibm.com, linux-pm@...r.kernel.org,
	linux-arch@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
	Richard Kuo <rkuo@...eaurora.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	linux-hexagon@...r.kernel.org
Subject: [PATCH 34/45] hexagon/smp: Use get/put_online_cpus_atomic() to
 prevent CPU offline

Once stop_machine() is gone from the CPU offline path, we won't be able
to depend on disabling preemption to prevent CPUs from going offline
from under us.

Use the get/put_online_cpus_atomic() APIs to prevent CPUs from going
offline, while invoking from atomic context.

Cc: Richard Kuo <rkuo@...eaurora.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: linux-hexagon@...r.kernel.org
Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@...ux.vnet.ibm.com>
---

 arch/hexagon/kernel/smp.c |    3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/hexagon/kernel/smp.c b/arch/hexagon/kernel/smp.c
index 0e364ca..30d4318 100644
--- a/arch/hexagon/kernel/smp.c
+++ b/arch/hexagon/kernel/smp.c
@@ -241,9 +241,12 @@ void smp_send_reschedule(int cpu)
 void smp_send_stop(void)
 {
 	struct cpumask targets;
+
+	get_online_cpus_atomic();
 	cpumask_copy(&targets, cpu_online_mask);
 	cpumask_clear_cpu(smp_processor_id(), &targets);
 	send_ipi(&targets, IPI_CPU_STOP);
+	put_online_cpus_atomic();
 }
 
 void arch_send_call_function_single_ipi(int cpu)

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