* Kirti Wankhede <kwankh...@nvidia.com> [2016-11-16 20:47:18 +0530]:
>
>
> On 11/16/2016 12:07 PM, Dong Jia Shi wrote:
> > * Kirti Wankhede <kwankh...@nvidia.com> [2016-11-15 20:59:55 +0530]:
> >
> > Hi Kirti,
> >
> > [...]
> >
> >> diff --git a/drivers/vfio/mdev/vfio_mdev.c b/drivers/vfio/mdev/vfio_mdev.c
> >> index ffc36758cb84..4fc63db38829 100644
> >> --- a/drivers/vfio/mdev/vfio_mdev.c
> >> +++ b/drivers/vfio/mdev/vfio_mdev.c
> >> @@ -24,6 +24,15 @@
> >> #define DRIVER_AUTHOR "NVIDIA Corporation"
> >> #define DRIVER_DESC "VFIO based driver for Mediated device"
> >>
> >> +static int vfio_mdev_notifier(struct notifier_block *nb, unsigned long
> >> action,
> >> + void *data)
> >> +{
> >> + struct mdev_device *mdev = container_of(nb, struct mdev_device, nb);
> >> + struct parent_device *parent = mdev->parent;
> >> +
> >> + return parent->ops->notifier(mdev, action, data);
> >> +}
> >> +
> >> static int vfio_mdev_open(void *device_data)
> >> {
> >> struct mdev_device *mdev = device_data;
> >> @@ -36,9 +45,18 @@ static int vfio_mdev_open(void *device_data)
> >> if (!try_module_get(THIS_MODULE))
> >> return -ENODEV;
> >>
> >> + if (likely(parent->ops->notifier)) {
> >> + mdev->nb.notifier_call = vfio_mdev_notifier;
> >> + if (vfio_register_notifier(&mdev->dev, &mdev->nb))
> >> + pr_err("Failed to register notifier for mdev\n");
> > I think we should just return here if the error value is not -ENOTTY.
> >
>
> It might be the case where iommu backend module might not support
> .register_notifier(). In that case vfio_register_notifier() returns
> -ENOTTY and that should not fail this open() call
> Changing it to:
>
> ret = vfio_register_notifier(&mdev->dev, &mdev->nb);
> if (ret && (ret != -ENOTTY)) {
> pr_err("Failed to register notifier for mdev\n");
> module_put(THIS_MODULE);
> return ret;
> }
Nod. And we need not call vfio_unregister_notifier once error occurs in
open() in this case.
>
> Thanks,
> Kirti
>
--
Dong Jia
