On 04/25/2013 05:47:39 AM, Alexander Graf wrote:
On 25.04.2013, at 11:43, Gleb Natapov wrote: >> +void kvm_device_put(struct kvm_device *dev) >> +{ >> + if (atomic_dec_and_test(&dev->users)) >> + dev->ops->destroy(dev); >> +} >> +>> +static int kvm_device_release(struct inode *inode, struct file *filp)>> +{ >> + struct kvm_device *dev = filp->private_data; >> + struct kvm *kvm = dev->kvm; >> + >> + kvm_device_put(dev); >> + kvm_put_kvm(kvm); > We may put kvm only if users goes to zero, otherwise kvm can be > freed while something holds a reference to a device. Why not make > kvm_device_put() do it?Nice catch. I'll change the patch so it does the kvm_put_kvm inside kvm_device_put's destroy branch.
No, please don't. The KVM reference being "put" here is associated with the file descriptor, not with the MPIC object. If you make that change I think you'll have circular references and thus a memory leak, because the vcpus can hold a reference to the MPIC object.
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