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

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Date:	Tue, 3 Dec 2013 17:19:11 +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 5:00 PM, Will Deacon <will.deacon@....com> wrote:
> On Mon, Dec 02, 2013 at 09:34:03AM +0000, Vinayak Kale wrote:
>> Add support for irq registration when pmu interrupt is percpu.
>>
>> Signed-off-by: Vinayak Kale <vkale@....com>
>> Signed-off-by: Tuan Phan <tphan@....com>
>> ---
>>  arch/arm64/kernel/perf_event.c |  116 +++++++++++++++++++++++++++++-----------
>>  1 file changed, 86 insertions(+), 30 deletions(-)
>>
>> diff --git a/arch/arm64/kernel/perf_event.c b/arch/arm64/kernel/perf_event.c
>> index cea1594..d2d562f 100644
>> --- a/arch/arm64/kernel/perf_event.c
>> +++ b/arch/arm64/kernel/perf_event.c
>> @@ -22,6 +22,7 @@
>>
>>  #include <linux/bitmap.h>
>>  #include <linux/interrupt.h>
>> +#include <linux/irq.h>
>>  #include <linux/kernel.h>
>>  #include <linux/export.h>
>>  #include <linux/perf_event.h>
>> @@ -363,26 +364,61 @@ validate_group(struct perf_event *event)
>>  }
>>
>>  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);
>> +     disable_percpu_irq(irq);
>> +}
>> +
>> +static void
>>  armpmu_release_hardware(struct arm_pmu *armpmu)
>>  {
>> -     int i, irq, irqs;
>> +     int irq;
>
> Why did you not make this unsigned, like I suggested?

Suggestion was to make 'irqs' variable unsigned and modify the check
for 'irqs' to if (!irqs).
This patch incorporates that suggestion.

We have to keep 'irq' signed only. 'platform_get_irq()' can return error value.

>
>> +     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;
>
> Then this is just an if (!irq), as I mentioned last time.

Please see my above comment.
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