On Thu, 18 May 2017, Will Deacon wrote:
> +static void __arm_spe_pmu_dev_probe(void *info)
> +{
> + dev_info(dev,
> + "probed for CPUs %*pbl [max_record_sz %u, align %u, features
> 0x%llx]\n",
> + cpumask_pr_args(&spe_pmu->supported_cpus),
> + spe_pmu->max_record_sz, spe_pmu->align, spe_pmu->features);
I have a hard time to spot the place which actually sets a CPU in the
supported_cpus mask. I must be missing something, but that's what grep
gives me:
+ cpumask_t supported_cpus;
+ return cpumap_print_to_pagebuf(true, buf, &spe_pmu->supported_cpus);
+ !cpumask_test_cpu(event->cpu, &spe_pmu->supported_cpus))
+ if (!cpumask_test_cpu(cpu, &spe_pmu->supported_cpus))
+ cpumask_pr_args(&spe_pmu->supported_cpus),
+ if (!cpumask_test_cpu(cpu, &spe_pmu->supported_cpus))
+ if (!cpumask_test_cpu(cpu, &spe_pmu->supported_cpus))
+ cpumask_t *mask = &spe_pmu->supported_cpus;
+ if (irq_get_percpu_devid_partition(irq, &spe_pmu->supported_cpus)) {
+ cpumask_t *mask = &spe_pmu->supported_cpus;
> +static int arm_spe_pmu_dev_init(struct arm_spe_pmu *spe_pmu)
> +{
> + int ret;
> + cpumask_t *mask = &spe_pmu->supported_cpus;
> +
> + /* Keep the hotplug state steady whilst we probe */
> + get_online_cpus();
> +
> + /* Make sure we probe the hardware on a relevant CPU */
> + ret = smp_call_function_any(mask, __arm_spe_pmu_dev_probe, spe_pmu, 1);
You can release the hotplug lock here again and spare all the goto magic.
> + if (ret || !(spe_pmu->features & SPE_PMU_FEAT_DEV_PROBED)) {
> + ret = -ENXIO;
> + goto out_put_cpus;
> + }
> +
> + /* Request our PPIs (note that the IRQ is still disabled) */
> + ret = request_percpu_irq(spe_pmu->irq, arm_spe_pmu_irq_handler, DRVNAME,
> + spe_pmu->handle);
> + if (ret)
> + goto out_put_cpus;
> +
> + /* Setup the CPUs in our mask -- this enables the IRQ */
> + on_each_cpu_mask(mask, __arm_spe_pmu_setup_one, spe_pmu, 1);
> +
> + /* Register our hotplug notifier now so we don't miss any events */
> + ret = cpuhp_state_add_instance_nocalls(arm_spe_pmu_online,
> + &spe_pmu->hotplug_node);
If you use cpuhp_state_add_instance() then you can spare the
on_each_cpu_mask(). The downside is that it will invoke the callback on the
non-supported CPUs as well, but you have protection in the callbacks anyway.
> +static int arm_spe_pmu_device_dt_probe(struct platform_device *pdev)
> +{
> + int ret;
> + struct arm_spe_pmu *spe_pmu;
> + struct device *dev = &pdev->dev;
> +
> + spe_pmu = devm_kzalloc(dev, sizeof(*spe_pmu), GFP_KERNEL);
> + if (!spe_pmu) {
> + dev_err(dev, "failed to allocate spe_pmu\n");
> + return -ENOMEM;
> + }
> +
> + spe_pmu->handle = alloc_percpu(typeof(*spe_pmu->handle));
> + if (!spe_pmu->handle)
> + return -ENOMEM;
> +
> + spe_pmu->pdev = pdev;
> + platform_set_drvdata(pdev, spe_pmu);
> +
> + ret = arm_spe_pmu_irq_probe(spe_pmu);
> + if (ret)
> + goto out_free_handle;
> +
> + ret = arm_spe_pmu_dev_init(spe_pmu);
> + if (ret)
> + goto out_free_handle;
> +
> + ret = arm_spe_pmu_perf_init(spe_pmu);
> + if (ret)
> + goto out_free_handle;
If that fails you leak the cpu hotplug instance. It's still enqueued.
> +static int arm_spe_pmu_device_remove(struct platform_device *pdev)
> +{
> + struct arm_spe_pmu *spe_pmu = platform_get_drvdata(pdev);
> + cpumask_t *mask = &spe_pmu->supported_cpus;
> +
> + arm_spe_pmu_perf_destroy(spe_pmu);
> +
> + get_online_cpus();
> + cpuhp_state_remove_instance_nocalls(arm_spe_pmu_online,
> + &spe_pmu->hotplug_node);
> + on_each_cpu_mask(mask, __arm_spe_pmu_stop_one, spe_pmu, 1);
You can spare that dance and just use cpuhp_state_remove_instance().
> + free_percpu_irq(spe_pmu->irq, spe_pmu->handle);
> + free_percpu(spe_pmu->handle);
Those two do not need hotplug protection.
Thanks
tglx
