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

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Message-ID: <20131203135002.GJ1169@mudshark.cambridge.arm.com>
Date:	Tue, 3 Dec 2013 13:50:02 +0000
From:	Will Deacon <will.deacon@....com>
To:	Vinayak Kale <vkale@....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 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?

> +	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.

Will
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