linux-kernel - Re: [PATCH 2/4] mdev: Make mdev alias unique among all mdevs

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Message-ID: <20190827122928.752e763b.cohuck@redhat.com>
Date:   Tue, 27 Aug 2019 12:29:28 +0200
From:   Cornelia Huck <cohuck@...hat.com>
To:     Parav Pandit <parav@...lanox.com>
Cc:     alex.williamson@...hat.com, jiri@...lanox.com,
        kwankhede@...dia.com, davem@...emloft.net, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, netdev@...r.kernel.org
Subject: Re: [PATCH 2/4] mdev: Make mdev alias unique among all mdevs

On Mon, 26 Aug 2019 15:41:17 -0500
Parav Pandit <parav@...lanox.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@...lanox.com>
> ---
>  drivers/vfio/mdev/mdev_core.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/drivers/vfio/mdev/mdev_core.c b/drivers/vfio/mdev/mdev_core.c
> index e825ff38b037..6eb37f0c6369 100644
> --- a/drivers/vfio/mdev/mdev_core.c
> +++ b/drivers/vfio/mdev/mdev_core.c
> @@ -375,6 +375,11 @@ int mdev_device_create(struct kobject *kobj, struct device *dev,
>  			ret = -EEXIST;
>  			goto mdev_fail;
>  		}
> +		if (tmp->alias && strcmp(tmp->alias, alias) == 0) {

Any way we can relay to the caller that the uuid was fine, but that we
had a hash collision? Duplicate uuids are much more obvious than a
collision here.

> +			mutex_unlock(&mdev_list_lock);
> +			ret = -EEXIST;
> +			goto mdev_fail;
> +		}
>  	}
>  
>  	mdev = kzalloc(sizeof(*mdev), GFP_KERNEL);