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Subject[PATCH v6 34/46] hexagon/smp: Use get/put_online_cpus_atomic() to prevent CPU offline
Date
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: Richard Kuo <rkuo@codeaurora.org>
Cc: linux-hexagon@vger.kernel.org
Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
---

arch/hexagon/kernel/smp.c | 5 +++++
1 file changed, 5 insertions(+)

diff --git a/arch/hexagon/kernel/smp.c b/arch/hexagon/kernel/smp.c
index 8e095df..ec87de9 100644
--- a/arch/hexagon/kernel/smp.c
+++ b/arch/hexagon/kernel/smp.c
@@ -112,6 +112,7 @@ void send_ipi(const struct cpumask *cpumask, enum ipi_message_type msg)
unsigned long cpu;
unsigned long retval;

+ get_online_cpus_atomic();
local_irq_save(flags);

for_each_cpu(cpu, cpumask) {
@@ -128,6 +129,7 @@ void send_ipi(const struct cpumask *cpumask, enum ipi_message_type msg)
}

local_irq_restore(flags);
+ put_online_cpus_atomic();
}

static struct irqaction ipi_intdesc = {
@@ -241,9 +243,12 @@ 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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