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Date: Sun, 26 Apr 2015 19:19:58 +0200 (CEST)
From: Julia Lawall <julia.lawall@lip6.fr>
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To: zhanghy@sangfor.com, mst@redhat.com, jasowang@redhat.com,
        zhanghy@sangfor.com, pbonzini@redhat.com, x86@kernel.org,
        kvm@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: KVM: x86: question about kvm_ioapic_destroy
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The function kvm_ioapic_destroy is defined as follows:

void kvm_ioapic_destroy(struct kvm *kvm)
{
        struct kvm_ioapic *ioapic = kvm->arch.vioapic;

        cancel_delayed_work_sync(&ioapic->eoi_inject);
        if (ioapic) {
                kvm_io_bus_unregister_dev(kvm, KVM_MMIO_BUS, &ioapic->dev);
                kvm->arch.vioapic = NULL;
                kfree(ioapic);
        }
}

Is there any way that cancel_delayed_work_sync can work if ioapic is NULL?  
Should the call be moved down under the NULL test?  Or is the NULL test 
not needed?  The NULL test has been there longer than the call to 
cancel_delayed_work_sync, which was introduced in 184564ef.

thanks,
julia