Re: [patch 1/3] KVM: x86: disallow multiple KVM_CREATE_IRQCHIP

["Michael S. Tsirkin" <mst@redhat.com>]

On Tue, Oct 27, 2009 at 01:10:43PM -0200, Marcelo Tosatti wrote:
> Otherwise kvm will leak memory on multiple KVM_CREATE_IRQCHIP.
> 
> CC: stable@kernel.org
> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
> 
> Index: kvm/arch/x86/kvm/x86.c
> ===================================================================
> --- kvm.orig/arch/x86/kvm/x86.c
> +++ kvm/arch/x86/kvm/x86.c
> @@ -2285,6 +2285,9 @@ long kvm_arch_vm_ioctl(struct file *filp
>  			goto out;
>  		break;
>  	case KVM_CREATE_IRQCHIP:
> +		r = -EEXIST;
> +		if (kvm->arch.vpic)
> +			goto out;
>  		r = -ENOMEM;
>  		kvm->arch.vpic = kvm_create_pic(kvm);
>  		if (kvm->arch.vpic) {
> @@ -2300,6 +2303,8 @@ long kvm_arch_vm_ioctl(struct file *filp
>  		if (r) {
>  			kfree(kvm->arch.vpic);
>  			kfree(kvm->arch.vioapic);
> +			kvm->arch.vpic = NULL;
> +			kvm->arch.vioapic = NULL;
>  			goto out;
>  		}
>  		break;

Is there a lock that protects this structure?
Can memory leak still occur if multiple threads call
KVM_CREATE_IRQCHIP in parallel?

> 
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