Re: [PATCH] ARM: perf: Don't sleep while atomic when enabling per-cpu interrupts

Stephen Boyd
2014-09-09T17:54:50Z

On 09/09/14 04:39, Will Deacon wrote:
> It's interesting that arm64 isn't affected by this problem, since we don't
> update the active_irqs mask for PPIs there and consequently just pass the
> irq instead of the cpu_pmu. I can't see why we actually need to update the
> active_irqs mask for arch/arm/, so could we remove that and follow arm64's
> lead instead? That would remove the need for a new struct definition too.
>

I guess you're saying that we don't need the active_irqs mask in the
percpu irq case? It looks like we still use it to determine when the
last CPU PMU has been disabled in the non-percpu case.

Here's the interdiff. Is there a reason arm64 casts data to an unsigned
int pointer when what's passed is an int pointer?

----8<-----

diff --git a/arch/arm/kernel/perf_event_cpu.c b/arch/arm/kernel/perf_event_cpu.c
index 1f24b47cd81e..4bf4cce759fe 100644
--- a/arch/arm/kernel/perf_event_cpu.c
+++ b/arch/arm/kernel/perf_event_cpu.c
@@ -74,28 +74,17 @@ static struct pmu_hw_events *cpu_pmu_get_cpu_events(void)
return this_cpu_ptr(&cpu_hw_events);
}

-struct pmu_enable {
- struct arm_pmu *pmu;
- int irq;
-};
-
static void cpu_pmu_enable_percpu_irq(void *data)
{
- struct pmu_enable *pmu_enable = data;
- struct arm_pmu *cpu_pmu = pmu_enable->pmu;
- int irq = pmu_enable->irq;
+ int irq = *(int *)data;

enable_percpu_irq(irq, IRQ_TYPE_NONE);
- cpumask_set_cpu(smp_processor_id(), &cpu_pmu->active_irqs);
}

static void cpu_pmu_disable_percpu_irq(void *data)
{
- struct pmu_enable *pmu_enable = data;
- struct arm_pmu *cpu_pmu = pmu_enable->pmu;
- int irq = pmu_enable->irq;
+ int irq = *(int *)data;

- cpumask_clear_cpu(smp_processor_id(), &cpu_pmu->active_irqs);
disable_percpu_irq(irq);
}

@@ -103,15 +92,12 @@ static void cpu_pmu_free_irq(struct arm_pmu *cpu_pmu)
{
int i, irq, irqs;
struct platform_device *pmu_device = cpu_pmu->plat_device;
- struct pmu_enable pmu_enable;

irqs = min(pmu_device->num_resources, num_possible_cpus());

irq = platform_get_irq(pmu_device, 0);
if (irq >= 0 && irq_is_percpu(irq)) {
- pmu_enable.pmu = cpu_pmu;
- pmu_enable.irq = irq;
- on_each_cpu(cpu_pmu_disable_percpu_irq, &pmu_enable, 1);
+ on_each_cpu(cpu_pmu_disable_percpu_irq, &irq, 1);
free_percpu_irq(irq, &percpu_pmu);
} else {
for (i = 0; i < irqs; ++i) {
@@ -128,7 +114,6 @@ static int cpu_pmu_request_irq(struct arm_pmu *cpu_pmu, irq_handler_t handler)
{
int i, err, irq, irqs;
struct platform_device *pmu_device = cpu_pmu->plat_device;
- struct pmu_enable pmu_enable;

if (!pmu_device)
return -ENODEV;
@@ -147,9 +132,7 @@ static int cpu_pmu_request_irq(struct arm_pmu *cpu_pmu, irq_handler_t handler)
irq);
return err;
}
- pmu_enable.pmu = cpu_pmu;
- pmu_enable.irq = irq;
- on_each_cpu(cpu_pmu_enable_percpu_irq, &pmu_enable, 1);
+ on_each_cpu(cpu_pmu_enable_percpu_irq, &irq, 1);
} else {
for (i = 0; i < irqs; ++i) {
err = 0;

--
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