[PATCH v6 43/46] tile: Use get/put_online_cpus_atomic() to preventCPU offline

From: Srivatsa S. Bhat
Date: Mon Feb 18 2013 - 07:46:38 EST

Once stop_machine() is gone from the CPU offline path, we won't be able to
depend on preempt_disable() or local_irq_disable() 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: Chris Metcalf <cmetcalf@xxxxxxxxxx>
Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@xxxxxxxxxxxxxxxxxx>

arch/tile/kernel/smp.c | 4 ++++
1 file changed, 4 insertions(+)

diff --git a/arch/tile/kernel/smp.c b/arch/tile/kernel/smp.c
index cbc73a8..fb30624 100644
--- a/arch/tile/kernel/smp.c
+++ b/arch/tile/kernel/smp.c
@@ -15,6 +15,7 @@

#include <linux/smp.h>
+#include <linux/cpu.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/irq.h>
@@ -82,9 +83,12 @@ void send_IPI_many(const struct cpumask *mask, int tag)
void send_IPI_allbutself(int tag)
struct cpumask mask;
+ get_online_cpus_atomic();
cpumask_copy(&mask, cpu_online_mask);
cpumask_clear_cpu(smp_processor_id(), &mask);
send_IPI_many(&mask, tag);
+ put_online_cpus_atomic();


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