Re: [04/17] [PATCH] Add kvm arch-specific core code for kvm/ia64.-V8

[Carsten Otte <cotte@de.ibm.com>]

Zhang, Xiantao wrote:
> Carsten Otte wrote:
>> Zhang, Xiantao wrote:
>>> Hi, Carsten
>>>      Why do you think it is racy?  In this function,
>>> target_vcpu->arch.launched should be set to 1 for the first run, and
>>> keep its value all the time.  Except the first IPI to wake up the
>>> vcpu, all IPIs received by target vcpu should go into "else"
>>> condition. So you mean the race condition exist in "else"  code ?
>> For example to lock against destroying that vcpu. Or, the waitqueue
>> may become active after if (waitqueue_active()) and before
>> wake_up_interruptible(). In that case, the target vcpu might sleep and
>> not get waken up by the ipi.
> I don't think it may cause issue, because the target vcpu at least can
> be waken up by the timer interrupt. 
> 
> But as you said,  x86 side also have the same race issue ? 
As far as I can tell, x86 does'nt have that race.