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SubjectRe: [PATCH V3 2/2] arm64: perf: add support for percpu pmu interrupt
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On Mon, Nov 18, 2013 at 8:10 PM, Marc Zyngier <marc.zyngier@arm.com> wrote:
> On 2013-11-18 14:18, Vinayak Kale wrote:
>>
>> On Mon, Nov 18, 2013 at 7:16 PM, Marc Zyngier <marc.zyngier@arm.com>
>> wrote:
>>>
>>> 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@apm.com>
>>>> Signed-off-by: Tuan Phan <tphan@apm.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.
>>
>> I don't think it's being misused. In case of invalid irq number, the
>> API would return null.
>
>
> And feeding an error code to irq_to_desc() doesn't disturb you?
Since the API handles the error condition and returns null, so it
won't break stuff.
But I think your earlier suggestion of checking invalid irq number
beforehand is better, since it would help to avoid wasting time in
searching the irq desc.
> Do you call that a normal use of the API? Humfff....
>
> M.
>
> --
> Fast, cheap, reliable. Pick two.
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