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

[Carsten O. <co...@de...>]

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.