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SubjectRe: [PATCH v13 12/22] vfio: Add notifier callback to parent's ops structure of mdev
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On 11/16/2016 12:07 PM, Dong Jia Shi wrote:
> * Kirti Wankhede <kwankhede@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;
}

Thanks,
Kirti

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