From mboxrd@z Thu Jan  1 00:00:00 1970
From: Gleb Natapov <gleb@redhat.com>
Subject: Re: [PATCH v3 7/8] Move IO APIC to its own lock.
Date: Thu, 13 Aug 2009 12:48:10 +0300
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Cc: avi@redhat.com, kvm@vger.kernel.org
To: Marcelo Tosatti <mtosatti@redhat.com>
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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.

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

--
			Gleb.