Re: [PATCH v1 2/5] mdev: Make mdev alias unique among all mdevs

Alex Williamson
2019-08-28T21:37:04Z

On Tue, 27 Aug 2019 14:16:51 -0500
Parav Pandit <parav@mellanox.com> wrote:

> Mdev alias should be unique among all the mdevs, so that when such alias
> is used by the mdev users to derive other objects, there is no
> collision in a given system.
>
> Signed-off-by: Parav Pandit <parav@mellanox.com>
>
> ---
> Changelog:
> v0->v1:
> - Fixed inclusiong of alias for NULL check
> - Added ratelimited debug print for sha1 hash collision error
> ---
> drivers/vfio/mdev/mdev_core.c | 7 +++++++
> 1 file changed, 7 insertions(+)
>
> diff --git a/drivers/vfio/mdev/mdev_core.c b/drivers/vfio/mdev/mdev_core.c
> index 62d29f57fe0c..4b9899e40665 100644
> --- a/drivers/vfio/mdev/mdev_core.c
> +++ b/drivers/vfio/mdev/mdev_core.c
> @@ -375,6 +375,13 @@ int mdev_device_create(struct kobject *kobj, struct device *dev,
> ret = -EEXIST;
> goto mdev_fail;
> }
> + if (tmp->alias && alias && strcmp(tmp->alias, alias) == 0) {

Nit, test if the device we adding has an alias before the device we're
testing against. The compiler can better optimize keeping alias hot.
Thanks,

Alex

> + mutex_unlock(&mdev_list_lock);
> + ret = -EEXIST;
> + dev_dbg_ratelimited(dev, "Hash collision in alias creation for UUID %pUl\n",
> + uuid);
> + goto mdev_fail;
> + }
> }
>
> mdev = kzalloc(sizeof(*mdev), GFP_KERNEL);