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SubjectRe: [PATCH v3 1/5] mdev: Introduce sha1 based mdev alias
On Sun,  1 Sep 2019 23:24:32 -0500
Parav Pandit <parav@mellanox.com> wrote:

> Some vendor drivers want an identifier for an mdev device that is
> shorter than the UUID, due to length restrictions in the consumers of
> that identifier.
>
> Add a callback that allows a vendor driver to request an alias of a
> specified length to be generated for an mdev device. If generated,
> that alias is checked for collisions.
>
> It is an optional attribute.
> mdev alias is generated using sha1 from the mdev name.
>
> Signed-off-by: Parav Pandit <parav@mellanox.com>
>
> ---
> Changelog:
> v1->v2:
> - Kept mdev_device naturally aligned
> - Added error checking for crypt_*() calls
> - Corrected a typo from 'and' to 'an'
> - Changed return type of generate_alias() from int to char*
> v0->v1:
> - Moved alias length check outside of the parent lock
> - Moved alias and digest allocation from kvzalloc to kzalloc
> - &alias[0] changed to alias
> - alias_length check is nested under get_alias_length callback check
> - Changed comments to start with an empty line
> - Fixed cleaunup of hash if mdev_bus_register() fails
> - Added comment where alias memory ownership is handed over to mdev device
> - Updated commit log to indicate motivation for this feature
> ---
> drivers/vfio/mdev/mdev_core.c | 123 ++++++++++++++++++++++++++++++-
> drivers/vfio/mdev/mdev_private.h | 5 +-
> drivers/vfio/mdev/mdev_sysfs.c | 13 ++--
> include/linux/mdev.h | 4 +
> 4 files changed, 135 insertions(+), 10 deletions(-)

(...)

> diff --git a/include/linux/mdev.h b/include/linux/mdev.h
> index 0ce30ca78db0..f036fe9854ee 100644
> --- a/include/linux/mdev.h
> +++ b/include/linux/mdev.h
> @@ -72,6 +72,9 @@ struct device *mdev_get_iommu_device(struct device *dev);
> * @mmap: mmap callback
> * @mdev: mediated device structure
> * @vma: vma structure
> + * @get_alias_length: Generate alias for the mdevs of this parent based on the
> + * mdev device name when it returns non zero alias length.

"Optional: If a non-zero alias length is returned, generate an alias
for this parent's mdevs based upon the mdev device name."

?

> + * It is optional.
> * Parent device that support mediated device should be registered with mdev
> * module with mdev_parent_ops structure.
> **/
> @@ -92,6 +95,7 @@ struct mdev_parent_ops {
> long (*ioctl)(struct mdev_device *mdev, unsigned int cmd,
> unsigned long arg);
> int (*mmap)(struct mdev_device *mdev, struct vm_area_struct *vma);
> + unsigned int (*get_alias_length)(void);
> };
>
> /* interface for exporting mdev supported type attributes */

Reviewed-by: Cornelia Huck <cohuck@redhat.com>

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