RE: [PATCH 1/4] mdev: Introduce sha1 based mdev alias

Parav Pandit
2019-08-27T11:12:39Z

> -----Original Message-----
> From: Cornelia Huck <cohuck@redhat.com>
> Sent: Tuesday, August 27, 2019 3:54 PM
> To: Parav Pandit <parav@mellanox.com>
> Cc: alex.williamson@redhat.com; Jiri Pirko <jiri@mellanox.com>;
> kwankhede@nvidia.com; davem@davemloft.net; kvm@vger.kernel.org; linux-
> kernel@vger.kernel.org; netdev@vger.kernel.org
> Subject: Re: [PATCH 1/4] mdev: Introduce sha1 based mdev alias
>
> On Mon, 26 Aug 2019 15:41:16 -0500
> Parav Pandit <parav@mellanox.com> wrote:
>
> > Whenever a parent requests to generate mdev alias, generate a mdev
> > alias.
> > It is an optional attribute that parent can request to generate for
> > each of its child mdev.
> > mdev alias is generated using sha1 from the mdev name.
>
> Maybe add some motivation here as well?
>
> "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 (via sha1) for an mdev device. If generated, that alias is
> checked for collisions."
>
I did described the motivation in the cover letter with example and this design discussion thread.
I will include above summary in v1.

> What about:
>
> * @get_alias_length: optional callback to specify length of the alias to create
> * Returns unsigned integer: length of the alias to be created,
> * 0 to not create an alias
>
Ack.

> I also think it might be beneficial to add a device parameter here now (rather
> than later); that seems to be something that makes sense.
>
Without showing the use, it shouldn't be added.

> > * 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 */