diff --git a/arch/arm/oprofile/op_model_mpcore.c b/arch/arm/oprofile/op_model_mpcore.c
index 898500718249..7791da791f5f 100644
--- a/arch/arm/oprofile/op_model_mpcore.c
+++ b/arch/arm/oprofile/op_model_mpcore.c
@@ -257,8 +257,13 @@ static void em_stop(void)
  */
 static void em_route_irq(int irq, unsigned int cpu)
 {
-	irq_desc[irq].affinity = cpumask_of_cpu(cpu);
-	irq_desc[irq].chip->set_affinity(irq, cpumask_of_cpu(cpu));
+	struct irq_desc *desc = irq_desc + irq;
+	cpumask_t mask = cpumask_of_cpu(cpu);
+
+	spin_lock_irq(&desc->lock);
+	desc->affinity = mask;
+	desc->chip->set_affinity(irq, mask);
+	spin_unlock_irq(&desc->lock);
 }
 
 static int em_setup(void)