Messages in this thread | | | From | Parav Pandit <> | Subject | RE: [PATCH 2/4] mdev: Make mdev alias unique among all mdevs | Date | Tue, 27 Aug 2019 16:13:27 +0000 |
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> -----Original Message----- > From: Alex Williamson <alex.williamson@redhat.com> > Sent: Tuesday, August 27, 2019 8:59 PM > To: Cornelia Huck <cohuck@redhat.com> > Cc: Parav Pandit <parav@mellanox.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 Tue, 27 Aug 2019 13:29:46 +0200 > Cornelia Huck <cohuck@redhat.com> wrote: > > > 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. > > It's a rare event, maybe just dev_dbg(dev, "Hash collision creating alias \"%s\" > for mdev device %pUl\n",... > Ok. dev_dbg_once() to avoid message flood.
> Thanks, > Alex > > > > > > + mutex_unlock(&mdev_list_lock); > > > > > + ret = -EEXIST; > > > > > + goto mdev_fail; > > > > > + } > > > > > } > > > > > > > > > > mdev = kzalloc(sizeof(*mdev), GFP_KERNEL); > > > > >
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