Re: [PATCH] irq: Exclude percpu IRQs from being fixed up

[Fengzhe Zhang <fengzhe.zhang@intel.com>]

On 2011/2/16 22:53, Jan Beulich wrote:
>>>> On 16.02.11 at 15:26, "Zhang, Fengzhe"<fengzhe.zhang@intel.com>  wrote:
>> irq: Exclude percpu IRQs from being fixed up
>>
>> Xen spin unlock uses spurious ipi "lock_kicker_irq" to wake up blocked vCPUs
>> waiting on that lock. This irq should always be disabled. However, when Dom0
>> is shuting down, function fixup_irqs is called which unmasks all irqs.
>> Function unmask_irq effectively re-enables lock_kicker_irq and its irq handler
>> is invoked which reports bug and crashes Dom0.
>>
>> This patch sets IRQ_PER_CPU flag in irq desc and excludes percpu IRQs from
>> being fixed up when taking CPUs down.
>>
>> Signed-off-by: Fengzhe Zhang<fengzhe.zhang@intel.com>
>>
>> diff --git a/arch/x86/kernel/irq_64.c b/arch/x86/kernel/irq_64.c
>> index 977d8b4..f0f9450 100644
>> --- a/arch/x86/kernel/irq_64.c
>> +++ b/arch/x86/kernel/irq_64.c
>> @@ -80,6 +80,9 @@ void fixup_irqs(void)
>>   		if (irq == 2)
>>   			continue;
>>
>> +		if (desc->status&  IRQ_PER_CPU)
>> +			continue;
>> +
>>   		/* interrupt's are disabled at this point */
>>   		spin_lock(&desc->lock);
>>
>> diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
>> index f34e231..26bc55a 100644
>> --- a/kernel/irq/manage.c
>> +++ b/kernel/irq/manage.c
>> @@ -727,10 +727,9 @@ __setup_irq(unsigned int irq, struct irq_desc *desc,
>> struct irqaction *new)
>>   				goto out_thread;
>>   		} else
>>   			compat_irq_chip_set_default_handler(desc);
>> -#if defined(CONFIG_IRQ_PER_CPU)
>
> Why? XEN should select IRQ_PER_CPU instead in its Kconfig.
>
> Jan
>
IRQ_PER_CPU switch is not found in current Kconfig. I'm not sure if this 
feature is going to be brought back in the short term. I remove the 
ifdef to set IRQ_PER_CPU flag in desc by default but still leave the IRQ 
handling logic unchanged. This is a temporary solution to fix system 
crash on poweroff. And this is the fix with minimum impact among the 
several solutions we tried.

-Fengzhe

>> +
>>   		if (new->flags&  IRQF_PERCPU)
>>   			desc->status |= IRQ_PER_CPU;
>> -#endif
>>
>>   		desc->status&= ~(IRQ_AUTODETECT | IRQ_WAITING | IRQ_ONESHOT |
>>   				  IRQ_INPROGRESS | IRQ_SPURIOUS_DISABLED);
>
>