From mboxrd@z Thu Jan  1 00:00:00 1970
From: Takuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>
Subject: Re: [RFC PATCH] KVM: Fix missing lock for kvm_io_bus_unregister_dev()
Date: Wed, 08 Dec 2010 14:27:37 +0900
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References: <20101208014506.4c18b52a.takuya.yoshikawa@gmail.com>
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Cc: avi@redhat.com, mtosatti@redhat.com, kvm@vger.kernel.org
To: Takuya Yoshikawa <takuya.yoshikawa@gmail.com>
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(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