Messages in this thread | | | Date | Fri, 10 Jan 2014 11:36:57 -0800 | From | Stephen Boyd <> | Subject | Re: [PATCH 2/7] ARM: perf_event: Support percpu irqs for the CPU PMU |
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On 01/10, Will Deacon wrote: > On Thu, Jan 09, 2014 at 07:17:29PM +0000, Stephen Boyd wrote: > > > We can avoid the hacky cast of the per-cpu dev token by using the > > cpu_pmu pointer directly, but we'll still need to pass something to the > > percpu interrupt handler otherwise the genirq layer doesn't allow us to > > request the PPI. I can pass hw_events I guess. Is that what you're > > thinking? Or were you thinking that we could just use > > cpu_pmu->handle_irq as the handler argument in request_percpu_irq()? I > > can't figure out how that is supposed to work. > > Actually, I was thinking you could remove cpu_pmu_dispatch_irq completely > and just pass the actual handler straight through to request_percpu_irq. On > arm64 we pass the hw_events as the pcpu token, so I'd be inclined to do the > same here unless there's a good reason not to. >
Passing the hw_events as the pcpu token here is kind of hacky. The reason is because the token is dereferenced into cpu_pmu in armv7pmu_handle_irq() like so:
struct arm_pmu *cpu_pmu = (struct arm_pmu *)dev;
It would be great if we could pass cpu_pmu directly to the request call like so:
request_percpu_irq(irq, cpu_pmu->handle_irq, "arm-pmu", &cpu_pmu);
but no. request_percpu_irq() wants a percpu pointer so this won't work. If cpu_pmu was declared as DEFINE_PER_CPU, this would work out just fine.
Should the cpu_pmu become a per-cpu variable? That sounds rather invasive.
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