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Date: Wed, 1 Aug 2018 16:11:52 +0100
From: Julien Thierry <julien.thierry@....com>
To: Ricardo Neri <ricardo.neri-calderon@...ux.intel.com>
Cc: linux-kernel@...r.kernel.org, tglx@...utronix.de,
peterz@...radead.org, marc.zyngier@....com, mingo@...nel.org
Subject: Re: [PATCH 2/4] genirq: Provide NMI management for percpu_devid
interrupts
On 01/08/18 04:11, Ricardo Neri wrote:
> On Tue, Jul 24, 2018 at 12:07:05PM +0100, Julien Thierry wrote:
>> Add support for percpu_devid interrupts treated as NMIs.
>>
>> Percpu_devid NMIs need to be setup/torn down on each CPU they target.
>>
>> The same restrictions as for global NMIs still apply for percpu_devid NMIs.
>>
>> Signed-off-by: Julien Thierry <julien.thierry@....com>
>> Cc: Thomas Gleixner <tglx@...utronix.de>
>> Cc: Peter Zijlstra <peterz@...radead.org>
>> Cc: Ingo Molnar <mingo@...nel.org>
>> Cc: Marc Zyngier <marc.zyngier@....com>
>> ---
>> include/linux/interrupt.h | 9 +++
>> kernel/irq/manage.c | 149 ++++++++++++++++++++++++++++++++++++++++++++++
>> 2 files changed, 158 insertions(+)
>>
>> diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h
>> index 3b1a320..59d3877 100644
>> --- a/include/linux/interrupt.h
>> +++ b/include/linux/interrupt.h
>> @@ -168,10 +168,15 @@ struct irqaction {
>> devname, percpu_dev_id);
>> }
>>
>> +extern int __must_check
>> +request_percpu_nmi(unsigned int irq, irq_handler_t handler,
>> + const char *devname, void __percpu *dev);
>> +
>> extern const void *free_irq(unsigned int, void *);
>> extern void free_percpu_irq(unsigned int, void __percpu *);
>>
>> extern const void *free_nmi(unsigned int irq, void *dev_id);
>> +extern void free_percpu_nmi(unsigned int irq, void __percpu *percpu_dev_id);
>>
>> struct device;
>>
>> @@ -224,7 +229,11 @@ struct irqaction {
>> extern void irq_wake_thread(unsigned int irq, void *dev_id);
>>
>> extern void disable_nmi_nosync(unsigned int irq);
>> +extern void disable_percpu_nmi(unsigned int irq);
>
> Shouldn't this be a disable_percpu_nmi_nosync() as disable_nmi_nosync()?
>
The naming of the disable_percpu_irq didn't include the nosync either
(and it doesn't wait for pending percpu_devid_irqs)
>> extern void enable_nmi(unsigned int irq);
>> +extern void enable_percpu_nmi(unsigned int irq, unsigned int type);
>> +extern int ready_percpu_nmi(unsigned int irq);
>> +extern void teardown_percpu_nmi(unsigned int irq);
>>
>> /* The following three functions are for the core kernel use only. */
>> extern void suspend_device_irqs(void);
>> diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
>> index 3b87143..ad41c4d 100644
>> --- a/kernel/irq/manage.c
>> +++ b/kernel/irq/manage.c
>> @@ -2162,6 +2162,11 @@ void enable_percpu_irq(unsigned int irq, unsigned int type)
>> }
>> EXPORT_SYMBOL_GPL(enable_percpu_irq);
>>
>> +void enable_percpu_nmi(unsigned int irq, unsigned int type)
>> +{
>> + enable_percpu_irq(irq, type);
>> +}
>> +
>> /**
>> * irq_percpu_is_enabled - Check whether the per cpu irq is enabled
>> * @irq: Linux irq number to check for
>> @@ -2201,6 +2206,11 @@ void disable_percpu_irq(unsigned int irq)
>> }
>> EXPORT_SYMBOL_GPL(disable_percpu_irq);
>>
>> +void disable_percpu_nmi(unsigned int irq)
>> +{
>> + disable_percpu_irq(irq);
>> +}
>> +
>> /*
>> * Internal function to unregister a percpu irqaction.
>> */
>> @@ -2232,6 +2242,8 @@ static struct irqaction *__free_percpu_irq(unsigned int irq, void __percpu *dev_
>> /* Found it - now remove it from the list of entries: */
>> desc->action = NULL;
>>
>> + desc->istate &= ~IRQS_NMI;
>> +
>> raw_spin_unlock_irqrestore(&desc->lock, flags);
>>
>> unregister_handler_proc(irq, action);
>> @@ -2285,6 +2297,19 @@ void free_percpu_irq(unsigned int irq, void __percpu *dev_id)
>> }
>> EXPORT_SYMBOL_GPL(free_percpu_irq);
>>
>> +void free_percpu_nmi(unsigned int irq, void __percpu *dev_id)
>> +{
>> + struct irq_desc *desc = irq_to_desc(irq);
>> +
>> + if (!desc || !irq_settings_is_per_cpu_devid(desc))
>> + return;
>> +
>> + if (WARN_ON(!(desc->istate & IRQS_NMI)))
>> + return;
>> +
>> + kfree(__free_percpu_irq(irq, dev_id));
>> +}
>> +
>> /**
>> * setup_percpu_irq - setup a per-cpu interrupt
>> * @irq: Interrupt line to setup
>> @@ -2375,6 +2400,130 @@ int __request_percpu_irq(unsigned int irq, irq_handler_t handler,
>> EXPORT_SYMBOL_GPL(__request_percpu_irq);
>>
>> /**
>> + * request_percpu_nmi - allocate a percpu interrupt line for NMI delivery
>> + * @irq: Interrupt line to allocate
>> + * @handler: Function to be called when the IRQ occurs.
>> + * @devname: An ascii name for the claiming device
>> + * @dev_id: A percpu cookie passed back to the handler function
>> + *
>> + * This call allocates interrupt resources and enables the
>> + * interrupt on the local CPU. If the interrupt is supposed to be
>> + * enabled on other CPUs, it has to be done on each CPU using
>> + * enable_percpu_nmi().
>> + *
>> + * Dev_id must be globally unique. It is a per-cpu variable, and
>> + * the handler gets called with the interrupted CPU's instance of
>> + * that variable.
>> + *
>> + * Interrupt lines requested for NMI delivering should have auto enabling
>> + * setting disabled.
>> + *
>> + * If the interrupt line cannot be used to deliver NMIs, function
>> + * will fail returning a negative value.
>> + */
>> +int request_percpu_nmi(unsigned int irq, irq_handler_t handler,
>> + const char *name, void __percpu *dev_id)
>> +{
>> + struct irqaction *action;
>> + struct irq_desc *desc;
>> + unsigned long flags;
>> + int retval;
>> +
>> + if (!handler)
>> + return -EINVAL;
>> +
>> + desc = irq_to_desc(irq);
>> +
>> + if (!desc || !irq_settings_can_request(desc)
>> + || !irq_settings_is_per_cpu_devid(desc)
>> + || irq_settings_can_autoenable(desc)
>> + || !irq_supports_nmi(desc))
>
> Shouldn't the logical operators go at the end of the line in a multi-line
> statement?
Yes, I'll fix that.
>
>> + return -EINVAL;
>> +
>> + /* The line cannot already be NMI */
>> + if (desc->istate & IRQS_NMI)
>> + return -EINVAL;
>> +
>> + action = kzalloc(sizeof(struct irqaction), GFP_KERNEL);
>> + if (!action)
>> + return -ENOMEM;
>> +
>> + action->handler = handler;
>> + action->flags = IRQF_PERCPU | IRQF_NO_SUSPEND | IRQF_NO_THREAD
>> + | IRQF_NOBALANCING;
>
> Shouldn't IRQF_NOBALANCING be aligned with IRQF_PERCPU;
>
Yes, I'll fix this as well.
Thanks,
--
Julien Thierry
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