Re: KVM: x86: question about kvm_ioapic_destroy

From: Paolo Bonzini
Date: Mon Apr 27 2015 - 08:13:59 EST

On 27/04/2015 12:05, Michael S. Tsirkin wrote:
> On Sun, Apr 26, 2015 at 07:19:58PM +0200, Julia Lawall wrote:
>> 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.
> I think the NULL test is not needed.
> kvm_ioapic_destroy is only called if kvm_ioapic_init
> completed successfully, and that sets kvm->arch.vioapic.

Agreed. By the way, in that case the cancel_delayed_work_sync is really
a nop.

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