Re: [PATCH 4/5] kvm: Replace vcpu->swait with rcuwait

[Paolo Bonzini]

On 23/04/20 10:41, Marc Zyngier wrote:
>>  
>> -	if (swait_active(kvm_arch_vcpu_wq(vcpu)))
>> +	if (rcu_dereference(kvm_arch_vpu_get_wait(vcpu)) != NULL)
> This doesn't compile (wrong function name, and rcu_dereference takes a
> variable). But whatever it would do if we fixed it looks dodgy. it isn't
> the rcuwait structure that you want to dereference, but rcuwait->task
> (we are checking whether we are called because we are blocking or being
> preempted).
> 

Yes, I agree.  Replacing swait with rcuwait is all good, but please make
the API look the same first.  Just like you added prepare_to_rcuwait and
finish_rcuwait, let's add rcuwait_active as well.

Actually let's do it like this:

1) Davidlohr, please post only patches 1-3 to "equalize" the swait and
rcuwait APIs.

2) Peter, please prepare a topic branch for those, or provide Acked-by

3) let's get everything else through the KVM tree.

Thanks,

Paolo