(2012/02/07 11:34), Liu Ping Fan wrote:
> static int kvm_vcpu_release(struct inode *inode, struct file *filp)
Is this a hot path?
If no, do you really need to pre-allocate the space for the next vcpus?
> {
> + int i;
> struct kvm_vcpu *vcpu = filp->private_data;
> + struct kvm *kvm = vcpu->kvm;
> + struct kvm_vcpu *vcpus_next;
> + filp->private_data = NULL;
> +
> + for (i = 0; i< atomic_read(&kvm->online_vcpus); i++) {
> + if (vcpu == kvm->vcpus+i)
> + break;
> + }
> + mutex_lock(&kvm->lock);
> + vcpus_next = kvm->vcpus_array +
> + ((kvm->vcpus - kvm->vcpus_array) ? 0 : KVM_MAX_VCPUS);
> +
> + memset(vcpus_next, 0, KVM_MAX_VCPUS*sizeof(struct kvm_vcpu *));
> + memcpy(vcpus_next, kvm->vcpus, i*sizeof(struct kvm_vcpu *));
> + memcpy(vcpus_next+i, kvm->vcpus+i+1,
> + (atomic_read(&kvm->online_vcpus)-i)*sizeof(struct kvm_vcpu *));
> + atomic_dec(&kvm->online_vcpus);
> + /* Removed vcpu can not be seen from vcpus[] */
This comment is confusing.
> + rcu_assign_pointer(kvm->vcpus, vcpus_next);
> + mutex_unlock(&kvm->lock);
> +
> + synchronize_rcu();
>
> - kvm_put_kvm(vcpu->kvm);
> + /* vcpu is out of list,drop it safely */
Ditto.
Do you mean something like
"now that there is no reader of it we can safely free this" ?
(Please do not trust me: I am not a native English speaker as you know.)
> + kvm_vcpu_destruct(vcpu);
> return 0;
> }
Takuya
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