The patch below does not apply to the 4.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 4608af8aa53e7f3922ddee695d023b7bcd5cb35b Mon Sep 17 00:00:00 2001

From: Marc Zyngier marc.zyngier@arm.com Date: Tue, 3 Oct 2017 18:14:13 +0100 Subject: [PATCH] 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 3c29d36702a8..5426c04fe24b 100644 --- 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; }