Re: [RFC PATCH] KVM: Fix missing lock for kvm_io_bus_unregister_dev()

[Takuya Yoshikawa <yoshikawa.takuya@xxxxxxxxxxxxx>]

(2010/12/08 1:45), Takuya Yoshikawa wrote:
> diff --git a/arch/x86/kvm/i8259.c b/arch/x86/kvm/i8259.c
> index f628234..d9fe35d 100644
> --- a/arch/x86/kvm/i8259.c
> +++ b/arch/x86/kvm/i8259.c
> @@ -596,7 +596,9 @@ void kvm_destroy_pic(struct kvm *kvm)
>   	struct kvm_pic *vpic = kvm->arch.vpic;
>
>   	if (vpic) {
> +		mutex_lock(&kvm->slots_lock);
>   		kvm_io_bus_unregister_dev(kvm, KVM_PIO_BUS,&vpic->dev);
> +		mutex_unlock(&kvm->slots_lock);
>   		kvm->arch.vpic = NULL;
>   		kfree(vpic);
>   	}

Ah, this seems to break the lock ordering

  kvm->lock --> kvm->slots_lock --> kvm->irq_lock

I'll recheck later.

  Takuya
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