On Tue, Aug 09, 2016 at 02:37:43PM +0200, Paolo Bonzini wrote:
>
>
> On 09/08/2016 14:20, Christoffer Dall wrote:
> > KVM devices were manipulating list data structures without any form of
> > synchronization, and some implementations of the create operations also
> > suffered from a lack of synchronization.
> >
> > Now when we've split the xics create operation into create and init, we
> > can hold the kvm->lock mutex while calling the create operation and when
> > manipulating the devices list.
> >
> > The error path in the generic code gets slightly ugly because we have to
> > take the mutex again and delete the device from the list, but holding
> > the mutex during anon_inode_getfd or releasing/locking the mutex in the
> > common non-error path seemed wrong.
> >
> > Signed-off-by: Christoffer Dall <christoffer.dall@xxxxxxxxxx>
>
> Very nice (and small), but please add a comment to the create member in
> kvm_device_ops.
Like this?:
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index d3c9b82..9c28b4d 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -1113,6 +1113,12 @@ struct kvm_device {
/* create, destroy, and name are mandatory */
struct kvm_device_ops {
const char *name;
+
+ /*
+ * create is called holding kvm->lock and any operations not suitable
+ * to do while holding the lock should be deferred to init (see
+ * below).
+ */
int (*create)(struct kvm_device *dev, u32 type);
/*
Thanks,
-Christoffer
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