Re: [PATCH v3 7/8] Move IO APIC to its own lock.

[Avi Kivity <avi@redhat.com>]

On 08/13/2009 12:48 PM, Gleb Natapov wrote:
> On Thu, Aug 13, 2009 at 06:13:30AM -0300, Marcelo Tosatti wrote:
>    
>>> +++ b/virt/kvm/ioapic.c
>>> @@ -182,6 +182,7 @@ int kvm_ioapic_set_irq(struct kvm_ioapic *ioapic, int irq, int level)
>>>   	union kvm_ioapic_redirect_entry entry;
>>>   	int ret = 1;
>>>
>>> +	mutex_lock(&ioapic->lock);
>>>   	if (irq>= 0&&  irq<  IOAPIC_NUM_PINS) {
>>>   		entry = ioapic->redirtbl[irq];
>>>   		level ^= entry.fields.polarity;
>>>        
>> But this is an RCU critical section now, right?
>>
>>      
> Correct! Forget about that. It was spinlock, but Avi prefers mutexes.
>    

Well, I prefer correct code to mutexes.

>    
>> If so, you can't sleep, must use a spinlock.
>>      
> Either that or I can collect callbacks in critical section and call them
> afterwords.
>    

There's also srcu.

-- 
error compiling committee.c: too many arguments to function