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

[Zhang, X. <xia...@in...>]

Carsten Otte wrote:
> 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.

Hi, Carsten
	I can't understand why it only exist at IA64 side. Thank you! 
Xiantao