linux-kernel - Re: [PATCH V6 2/2] arm64: perf: add support for percpu pmu interrupt

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Date:	Wed, 4 Dec 2013 11:56:27 +0530
From:	Vinayak Kale <vkale@....com>
To:	Will Deacon <will.deacon@....com>
Cc:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"tglx@...utronix.de" <tglx@...utronix.de>,
	"patches@....com" <patches@....com>,
	"jcm@...hat.com" <jcm@...hat.com>,
	"sboyd@...eaurora.org" <sboyd@...eaurora.org>,
	Marc Zyngier <Marc.Zyngier@....com>, Tuan Phan <tphan@....com>
Subject: Re: [PATCH V6 2/2] arm64: perf: add support for percpu pmu interrupt

On Tue, Dec 3, 2013 at 7:20 PM, Will Deacon <will.deacon@....com> wrote:
> On Mon, Dec 02, 2013 at 09:34:03AM +0000, Vinayak Kale wrote:
>>  static void
>> +armpmu_disable_percpu_irq(void *data)
>> +{
>> +     struct arm_pmu *armpmu = data;
>> +     struct platform_device *pmu_device = armpmu->plat_device;
>> +     int irq = platform_get_irq(pmu_device, 0);
>> +
>> +     cpumask_test_and_clear_cpu(smp_processor_id(), &armpmu->active_irqs);
>
> Why not just cpumask_clear_cpu?

Yes, that would have serve the purpose. It was due to dumb copy/paste
from non-percpu counterpart.

>
>> +     disable_percpu_irq(irq);
>> +}
>> +
>> +static void
>>  armpmu_release_hardware(struct arm_pmu *armpmu)
>>  {
>> -     int i, irq, irqs;
>> +     int irq;
>> +     unsigned int i, irqs;
>>       struct platform_device *pmu_device = armpmu->plat_device;
>>
>>       irqs = min(pmu_device->num_resources, num_possible_cpus());
>> +     if (!irqs)
>> +             return;
>>
>> -     for (i = 0; i < irqs; ++i) {
>> -             if (!cpumask_test_and_clear_cpu(i, &armpmu->active_irqs))
>> -                     continue;
>> -             irq = platform_get_irq(pmu_device, i);
>> -             if (irq >= 0)
>> -                     free_irq(irq, armpmu);
>> +     irq = platform_get_irq(pmu_device, 0);
>> +     if (irq <= 0)
>> +             return;
>> +
>> +     if (irq_is_percpu(irq)) {
>> +             on_each_cpu(armpmu_disable_percpu_irq, armpmu, 1);
>> +             free_percpu_irq(irq, &cpu_hw_events);
>> +     } else {
>> +             for (i = 0; i < irqs; ++i) {
>> +                     if (!cpumask_test_and_clear_cpu(i, &armpmu->active_irqs))
>> +                             continue;
>> +                     irq = platform_get_irq(pmu_device, i);
>> +                     if (irq > 0)
>> +                             free_irq(irq, armpmu);
>> +             }
>>       }
>>  }
>>
>> +static void
>> +armpmu_enable_percpu_irq(void *data)
>> +{
>> +     struct arm_pmu *armpmu = data;
>> +     struct platform_device *pmu_device = armpmu->plat_device;
>> +     int irq = platform_get_irq(pmu_device, 0);
>> +
>> +     enable_percpu_irq(irq, IRQ_TYPE_NONE);
>> +     cpumask_set_cpu(smp_processor_id(), &armpmu->active_irqs);
>
> Hmm, wouldn't it make more sense to pass the irq in data, then deal with the
> mask in the caller? (since the mask will *always* be updated by each CPU).
>
> Similarly for the disable path.

Okay.
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