bus: arm-cci: Fix use of smp_processor_id() in preemptible context

The ARM CCI driver seem to be using smp_processor_id() in a
preemptible context, which is likely to make a DEBUG_PREMPT
kernel scream at boot time.

Turn this into a get_cpu()/put_cpu() that extends over the CPU
hotplug registration, making sure that we don't race against
a CPU down operation.

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Cc: stable@vger.kernel.org # 4.2+
Signed-off-by: Pawel Moll <pawel.moll@arm.com>

diff --git a/drivers/bus/arm-cci.c b/drivers/bus/arm-cci.c
index 3c29d36702a8eceb4eabd5ed36cf3188adeb1694..5426c04fe24bc88faa88a2cff0624ccbce277ebe 100644 (file)
--- a/drivers/bus/arm-cci.c
+++ b/drivers/bus/arm-cci.c
@@ -1755,14 +1755,17 @@ static int cci_pmu_probe(struct platform_device *pdev)
        raw_spin_lock_init(&cci_pmu->hw_events.pmu_lock);
        mutex_init(&cci_pmu->reserve_mutex);
        atomic_set(&cci_pmu->active_events, 0);
-       cpumask_set_cpu(smp_processor_id(), &cci_pmu->cpus);
+       cpumask_set_cpu(get_cpu(), &cci_pmu->cpus);
 
        ret = cci_pmu_init(cci_pmu, pdev);
-       if (ret)
+       if (ret) {
+               put_cpu();
                return ret;
+       }
 
        cpuhp_state_add_instance_nocalls(CPUHP_AP_PERF_ARM_CCI_ONLINE,
                                         &cci_pmu->node);
+       put_cpu();
        pr_info("ARM %s PMU driver probed", cci_pmu->model->name);
        return 0;
 }