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Message-ID: <3545e6650079200b6b364df14ef14a4f@www.loen.fr>
Date: Mon, 18 Nov 2013 13:46:09 +0000
From: Marc Zyngier <marc.zyngier@....com>
To: Vinayak Kale <vkale@....com>
Cc: <linux-kernel@...r.kernel.org>,
<linux-arm-kernel@...ts.infradead.org>, <will.deacon@....com>,
<patches@....com>, <jcm@...hat.com>, <tglx@...utronix.de>,
Tuan Phan <tphan@....com>
Subject: Re: [PATCH V3 2/2] arm64: perf: add support for percpu pmu interrupt
Vinayak,
On 2013-11-18 13:22, 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 | 102
> +++++++++++++++++++++++++++++-----------
> 1 file changed, 74 insertions(+), 28 deletions(-)
>
> diff --git a/arch/arm64/kernel/perf_event.c
> b/arch/arm64/kernel/perf_event.c
> index cea1594..23475f6 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>
> @@ -363,22 +364,51 @@ 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;
> struct platform_device *pmu_device = armpmu->plat_device;
>
> - irqs = min(pmu_device->num_resources, num_possible_cpus());
> + irq = platform_get_irq(pmu_device, 0);
>
> - 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);
> + if (irq_to_desc(irq) && irq_is_percpu(irq)) {
Why do you need to check the irq_desc here? It really looks like a
misuse of the API.
Instead, you should check the value of irq itself (it should be
strictly positive).
> + on_each_cpu(armpmu_disable_percpu_irq, armpmu, 1);
> + free_percpu_irq(irq, &cpu_hw_events);
> + } else {
> + irqs = min(pmu_device->num_resources, num_possible_cpus());
> +
> + 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)
irq == 0 means "no-irq". You should handle it as an error case.
> + 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, 0);
> + cpumask_set_cpu(smp_processor_id(), &armpmu->active_irqs);
> +}
> +
> static int
> armpmu_reserve_hardware(struct arm_pmu *armpmu)
> {
> @@ -396,34 +426,50 @@ armpmu_reserve_hardware(struct arm_pmu *armpmu)
> return -ENODEV;
> }
>
> - for (i = 0; i < irqs; ++i) {
> - err = 0;
> - irq = platform_get_irq(pmu_device, i);
> - if (irq < 0)
> - continue;
> + irq = platform_get_irq(pmu_device, 0);
>
> - /*
> - * If we have a single PMU interrupt that we can't shift,
> - * assume that we're running on a uniprocessor machine and
> - * continue. Otherwise, continue without this interrupt.
> - */
> - if (irq_set_affinity(irq, cpumask_of(i)) && irqs > 1) {
> - pr_warning("unable to set irq affinity (irq=%d, cpu=%u)\n",
> - irq, i);
> - continue;
> - }
> + if (irq_to_desc(irq) && irq_is_percpu(irq)) {
Same comment about irq_to_desc.
> + err = request_percpu_irq(irq, armpmu->handle_irq,
> + "arm-pmu", &cpu_hw_events);
>
> - err = request_irq(irq, armpmu->handle_irq,
> - IRQF_NOBALANCING,
> - "arm-pmu", armpmu);
> if (err) {
> - pr_err("unable to request IRQ%d for ARM PMU counters\n",
> - irq);
> + pr_err("unable to request percpu IRQ%d for ARM PMU counters\n",
> + irq);
> armpmu_release_hardware(armpmu);
> return err;
> }
>
> - cpumask_set_cpu(i, &armpmu->active_irqs);
> + on_each_cpu(armpmu_enable_percpu_irq, armpmu, 1);
> + } else {
> + for (i = 0; i < irqs; ++i) {
> + err = 0;
> + irq = platform_get_irq(pmu_device, i);
> + if (irq < 0)
Same comment about irq == 0.
> + continue;
> +
> + /*
> + * If we have a single PMU interrupt that we can't shift,
> + * assume that we're running on a uniprocessor machine and
> + * continue. Otherwise, continue without this interrupt.
> + */
> + if (irq_set_affinity(irq, cpumask_of(i)) && irqs > 1) {
> + pr_warning("unable to set irq affinity (irq=%d, cpu=%u)\n",
> + irq, i);
> + continue;
> + }
> +
> + err = request_irq(irq, armpmu->handle_irq,
> + IRQF_NOBALANCING,
> + "arm-pmu", armpmu);
> + if (err) {
> + pr_err("unable to request IRQ%d for ARM PMU counters\n",
> + irq);
> + armpmu_release_hardware(armpmu);
> + return err;
> + }
> +
> + cpumask_set_cpu(i, &armpmu->active_irqs);
> + }
> }
>
> return 0;
--
Fast, cheap, reliable. Pick two.
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