On Mon, 2013-01-28 at 09:54 +0000, Pandarathil, Vijaymohan R wrote:
> - Added vfio_device_get_from_vdev(), vfio_device_put_vdev()
> as wrappers to get/put reference to vfio_device from struct device.
>
> - Added vfio_device_data() as a wrapper to get device_data from
> vfio_device.
>
> Signed-off-by: Vijay Mohan Pandarathil <vijaymohan.pandarathil@xxxxxx>
> ---
> drivers/vfio/vfio.c | 47 +++++++++++++++++++++++++++++++++++++++++------
> include/linux/vfio.h | 3 +++
> 2 files changed, 44 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
> index 12c264d..c2ff1b2 100644
> --- a/drivers/vfio/vfio.c
> +++ b/drivers/vfio/vfio.c
> @@ -642,8 +642,13 @@ int vfio_add_group_dev(struct device *dev,
> }
> EXPORT_SYMBOL_GPL(vfio_add_group_dev);
>
> -/* Test whether a struct device is present in our tracking */
> -static bool vfio_dev_present(struct device *dev)
> +/**
> + * This does a get on the corresponding iommu_group,
> + * vfio_group and the vfio_device. Callers of this
> + * function will hae to call vfio_put_vdev() to
s/hae/have/
Note that your commit log and the patch don't agree on names.
vfio_device_get_from_dev vs vfio_device_get_from_vdev. vfio_put_vdev vs
vfio_device_put_vdev. Personally I think they should be:
vfio_device_get_from_dev
vfio_device_put
> + * remove the reference to all objects.
Why do we need to hold references to all the objects? Holding a
reference to a vfio_device should implicitly hold the vfio_group, which
implicitly holds the iommu_group. We have to get each to get to the
vfio_device, but once we hold of that reference I believe we can let the
others go. Is this not the case?
> + */
> +void *vfio_device_get_from_dev(struct device *dev)
Return should be struct vfio_device*. It doesn't have to be void to be
opaque.
> {
> struct iommu_group *iommu_group;
> struct vfio_group *group;
> @@ -651,25 +656,55 @@ static bool vfio_dev_present(struct device *dev)
>
> iommu_group = iommu_group_get(dev);
> if (!iommu_group)
> - return false;
> + return NULL;
>
> group = vfio_group_get_from_iommu(iommu_group);
> if (!group) {
> iommu_group_put(iommu_group);
> - return false;
> + return NULL;
> }
>
> device = vfio_group_get_device(group, dev);
> if (!device) {
> vfio_group_put(group);
> iommu_group_put(iommu_group);
> - return false;
> + return NULL;
> }
> + return device;
> +}
> +EXPORT_SYMBOL_GPL(vfio_device_get_from_dev);
> +
> +void *vfio_device_data(void *data)
> +{
Why wouldn't this take struct vfio_device*? We're ignoring free type
checking errors even though the user should be treating the device as
opaque.
> + struct vfio_device *device = data;
> + return device->device_data;
> +}
> +EXPORT_SYMBOL_GPL(vfio_device_data);
> +
> +void vfio_device_put_vdev(void *data)
> +{
This also should take a struct vfio_device* and be called
vfio_device_put(). If we fix the above extra reference holding then
it's just the existingvfio_device_put, which just needs to be exported.
> + struct vfio_device *device = data;
> + struct vfio_group *group = device->group;
> + struct iommu_group *iommu_group = group->iommu_group;
>
> vfio_device_put(device);
> vfio_group_put(group);
> iommu_group_put(iommu_group);
> - return true;
> + return;
Unnecessary explicit return. Thanks,
Alex
> +}
> +EXPORT_SYMBOL_GPL(vfio_device_put_vdev);
> +
> +/* Test whether a struct device is present in our tracking */
> +static bool vfio_dev_present(struct device *dev)
> +{
> + struct vfio_device *device;
> +
> + device = vfio_device_get_from_dev(dev);
> + if (device) {
> + vfio_device_put_vdev(device);
> + return true;
> + } else
> + return false;
> }
>
> /*
> diff --git a/include/linux/vfio.h b/include/linux/vfio.h
> index ab9e862..e550c09 100644
> --- a/include/linux/vfio.h
> +++ b/include/linux/vfio.h
> @@ -45,6 +45,9 @@ extern int vfio_add_group_dev(struct device *dev,
> void *device_data);
>
> extern void *vfio_del_group_dev(struct device *dev);
> +extern void *vfio_device_get_from_dev(struct device *dev);
> +extern void vfio_device_put_vdev(void *device);
> +extern void *vfio_device_data(void *device);
>
> /**
> * struct vfio_iommu_driver_ops - VFIO IOMMU driver callbacks
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