Messages in this thread Patch in this message | | | Date | Tue, 27 Aug 2019 13:29:46 +0200 | From | Cornelia Huck <> | Subject | Re: [PATCH 2/4] mdev: Make mdev alias unique among all mdevs |
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On Tue, 27 Aug 2019 11:08:59 +0000 Parav Pandit <parav@mellanox.com> wrote:
> > -----Original Message----- > > From: Cornelia Huck <cohuck@redhat.com> > > Sent: Tuesday, August 27, 2019 3:59 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 2/4] mdev: Make mdev alias unique among all mdevs > > > > On Mon, 26 Aug 2019 15:41:17 -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> > > > --- > > > 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. > > > How do you want to relay this rare event? > Netlink interface has way to return the error message back, but sysfs is limited due to its error code based interface.
I don't know, that's why I asked :)
The problem is that "uuid already used" and "hash collision" are indistinguishable. While "use a different uuid" will probably work in both cases, "increase alias length" might be a good alternative in some cases.
But if there is no good way to relay the problem, we can live with it.
> > > > + mutex_unlock(&mdev_list_lock); > > > + ret = -EEXIST; > > > + goto mdev_fail; > > > + } > > > } > > > > > > mdev = kzalloc(sizeof(*mdev), GFP_KERNEL); >
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