Re: [PATCH 2/2] xen: implement IRQ_WORK_VECTOR handler
From: Lin Ming
Date: Thu Apr 19 2012 - 04:47:09 EST
On Tue, Apr 17, 2012 at 4:32 AM, Konrad Rzeszutek Wilk
<konrad.wilk@xxxxxxxxxx> wrote:
> On Sun, Apr 15, 2012 at 02:09:32PM +0800, Lin Ming wrote:
>> Signed-off-by: Lin Ming <mlin@xxxxxxxxxxxxx>
>> ---
>> arch/x86/include/asm/xen/events.h | 1 +
>> arch/x86/xen/smp.c | 30 ++++++++++++++++++++++++++++++
>> 2 files changed, 31 insertions(+), 0 deletions(-)
>>
>> diff --git a/arch/x86/include/asm/xen/events.h b/arch/x86/include/asm/xen/events.h
>> index 1df3541..cc146d5 100644
>> --- a/arch/x86/include/asm/xen/events.h
>> +++ b/arch/x86/include/asm/xen/events.h
>> @@ -6,6 +6,7 @@ enum ipi_vector {
>> XEN_CALL_FUNCTION_VECTOR,
>> XEN_CALL_FUNCTION_SINGLE_VECTOR,
>> XEN_SPIN_UNLOCK_VECTOR,
>> + XEN_IRQ_WORK_VECTOR,
>>
>> XEN_NR_IPIS,
>> };
>> diff --git a/arch/x86/xen/smp.c b/arch/x86/xen/smp.c
>> index 2dc6628..92ad12d 100644
>> --- a/arch/x86/xen/smp.c
>> +++ b/arch/x86/xen/smp.c
>> @@ -16,6 +16,7 @@
>> #include <linux/err.h>
>> #include <linux/slab.h>
>> #include <linux/smp.h>
>> +#include <linux/irq_work.h>
>>
>> #include <asm/paravirt.h>
>> #include <asm/desc.h>
>> @@ -41,10 +42,12 @@ cpumask_var_t xen_cpu_initialized_map;
>> static DEFINE_PER_CPU(int, xen_resched_irq);
>> static DEFINE_PER_CPU(int, xen_callfunc_irq);
>> static DEFINE_PER_CPU(int, xen_callfuncsingle_irq);
>> +static DEFINE_PER_CPU(int, xen_irq_work);
>> static DEFINE_PER_CPU(int, xen_debug_irq) = -1;
>>
>> static irqreturn_t xen_call_function_interrupt(int irq, void *dev_id);
>> static irqreturn_t xen_call_function_single_interrupt(int irq, void *dev_id);
>> +static irqreturn_t xen_irq_work_interrupt(int irq, void *dev_id);
>>
>> /*
>> * Reschedule call back.
>> @@ -143,6 +146,17 @@ static int xen_smp_intr_init(unsigned int cpu)
>> goto fail;
>> per_cpu(xen_callfuncsingle_irq, cpu) = rc;
>>
>> + callfunc_name = kasprintf(GFP_KERNEL, "irqwork%d", cpu);
>> + rc = bind_ipi_to_irqhandler(XEN_IRQ_WORK_VECTOR,
>> + cpu,
>> + xen_irq_work_interrupt,
>> + IRQF_DISABLED|IRQF_PERCPU|IRQF_NOBALANCING,
>> + callfunc_name,
>> + NULL);
>> + if (rc < 0)
>> + goto fail;
>> + per_cpu(xen_irq_work, cpu) = rc;
>> +
>> return 0;
>>
>> fail:
>> @@ -155,6 +169,8 @@ static int xen_smp_intr_init(unsigned int cpu)
>> if (per_cpu(xen_callfuncsingle_irq, cpu) >= 0)
>> unbind_from_irqhandler(per_cpu(xen_callfuncsingle_irq, cpu),
>> NULL);
>> + if (per_cpu(xen_irq_work, cpu) >= 0)
>> + unbind_from_irqhandler(per_cpu(xen_irq_work, cpu), NULL);
>>
>> return rc;
>> }
>> @@ -509,6 +525,9 @@ static inline int xen_map_vector(int vector)
>> case CALL_FUNCTION_SINGLE_VECTOR:
>> xen_vector = XEN_CALL_FUNCTION_SINGLE_VECTOR;
>> break;
>> + case IRQ_WORK_VECTOR:
>> + xen_vector = XEN_IRQ_WORK_VECTOR;
>> + break;
>> default:
>> xen_vector = -1;
>> printk(KERN_ERR "xen: vector 0x%x is not implemented\n",
>> @@ -588,6 +607,16 @@ static irqreturn_t xen_call_function_single_interrupt(int irq, void *dev_id)
>> return IRQ_HANDLED;
>> }
>>
>> +static irqreturn_t xen_irq_work_interrupt(int irq, void *dev_id)
>> +{
>> + irq_enter();
>> + inc_irq_stat(apic_irq_work_irqs);
>> + irq_work_run();
>
> I think this usually done the other way around:
>
> irq_work_run()
> inc_irq_stat(apic_irq_work_irqs)
>
> Or is there an excellent reason for doing it this way?
Copy & paste from smp_irq_work_interrupt().
But I think there is no much difference.
Anyway, I can change it if needed.
Thanks,
Lin Ming
>
>> + irq_exit();
>> +
>> + return IRQ_HANDLED;
>> +}
>> +
>> static const struct smp_ops xen_smp_ops __initconst = {
>> .smp_prepare_boot_cpu = xen_smp_prepare_boot_cpu,
>> .smp_prepare_cpus = xen_smp_prepare_cpus,
>> @@ -634,6 +663,7 @@ static void xen_hvm_cpu_die(unsigned int cpu)
>> unbind_from_irqhandler(per_cpu(xen_callfunc_irq, cpu), NULL);
>> unbind_from_irqhandler(per_cpu(xen_debug_irq, cpu), NULL);
>> unbind_from_irqhandler(per_cpu(xen_callfuncsingle_irq, cpu), NULL);
>> + unbind_from_irqhandler(per_cpu(xen_irq_work, cpu), NULL);
>> native_cpu_die(cpu);
>> }
>>
>> --
>> 1.7.2.5
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