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From: Parav Pandit <parav@mellanox.com>
To: Alex Williamson <alex.williamson@redhat.com>,
	Cornelia Huck <cohuck@redhat.com>
Cc: Jiri Pirko <jiri@mellanox.com>,
	"kwankhede@nvidia.com" <kwankhede@nvidia.com>,
	"davem@davemloft.net" <davem@davemloft.net>,
	"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"netdev@vger.kernel.org" <netdev@vger.kernel.org>
Subject: RE: [PATCH 2/4] mdev: Make mdev alias unique among all mdevs
Date: Tue, 27 Aug 2019 16:13:27 +0000	[thread overview]
Message-ID: <AM0PR05MB486671BB1CD562D070F0C0F2D1A00@AM0PR05MB4866.eurprd05.prod.outlook.com> (raw)
In-Reply-To: <20190827092855.29702347@x1.home>



> -----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);
> > >
> >


  parent reply	other threads:[~2019-08-27 16:13 UTC|newest]

Thread overview: 96+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-26 20:41 [PATCH 0/4] Introduce variable length mdev alias Parav Pandit
2019-08-26 20:41 ` [PATCH 1/4] mdev: Introduce sha1 based " Parav Pandit
2019-08-27  1:44   ` Alex Williamson
2019-08-27  1:51     ` Alex Williamson
2019-08-27  4:24     ` Parav Pandit
2019-08-27 10:24   ` Cornelia Huck
2019-08-27 11:12     ` Parav Pandit
2019-08-27 11:24       ` Cornelia Huck
2019-08-27 11:33         ` Parav Pandit
2019-08-27 11:41           ` Cornelia Huck
2019-08-27 11:57             ` Parav Pandit
2019-08-27 13:35               ` Cornelia Huck
2019-08-27 16:50                 ` Alex Williamson
2019-08-27 11:16     ` Parav Pandit
2019-08-26 20:41 ` [PATCH 2/4] mdev: Make mdev alias unique among all mdevs Parav Pandit
2019-08-26 23:02   ` Mark Bloch
2019-08-27  4:28     ` Parav Pandit
2019-08-27 15:23       ` Alex Williamson
2019-08-27 16:16         ` Parav Pandit
2019-08-27 10:29   ` Cornelia Huck
2019-08-27 11:08     ` Parav Pandit
2019-08-27 11:29       ` Cornelia Huck
2019-08-27 15:28         ` Alex Williamson
2019-08-27 15:39           ` Cornelia Huck
2019-08-27 16:13           ` Parav Pandit [this message]
2019-08-27 16:24             ` Alex Williamson
2019-08-27 18:54               ` Parav Pandit
2019-08-26 20:41 ` [PATCH 3/4] mdev: Expose mdev alias in sysfs tree Parav Pandit
2019-08-27  1:53   ` Alex Williamson
2019-08-27  3:30     ` Parav Pandit
2019-08-27 10:47   ` Cornelia Huck
2019-08-27 11:07     ` Parav Pandit
2019-08-27 11:34       ` Cornelia Huck
2019-08-27 11:52         ` Parav Pandit
2019-08-27 11:55           ` Cornelia Huck
2019-08-27 12:00             ` Parav Pandit
2019-08-26 20:41 ` [PATCH 4/4] mtty: Optionally support mtty alias Parav Pandit
2019-08-27 13:11 ` [PATCH 0/4] Introduce variable length mdev alias Parav Pandit
2019-08-27 13:31   ` Cornelia Huck
2019-08-27 17:48   ` Alex Williamson
2019-08-27 18:11     ` Parav Pandit
2019-08-27 19:16 ` [PATCH v1 0/5] " Parav Pandit
2019-08-27 19:16   ` [PATCH v1 1/5] mdev: Introduce sha1 based " Parav Pandit
2019-08-28 21:25     ` Alex Williamson
2019-08-28 21:34       ` Alex Williamson
2019-08-29  9:07         ` Parav Pandit
2019-08-29  9:06       ` Parav Pandit
2019-08-27 19:16   ` [PATCH v1 2/5] mdev: Make mdev alias unique among all mdevs Parav Pandit
2019-08-28 21:36     ` Alex Williamson
2019-08-29  9:07       ` Parav Pandit
2019-08-27 19:16   ` [PATCH v1 3/5] mdev: Expose mdev alias in sysfs tree Parav Pandit
2019-08-27 19:16   ` [PATCH v1 4/5] mdev: Update sysfs documentation Parav Pandit
2019-08-27 19:16   ` [PATCH v1 5/5] mtty: Optionally support mtty alias Parav Pandit
2019-08-29 11:18 ` [PATCH v2 0/6] Introduce variable length mdev alias Parav Pandit
2019-08-29 11:18   ` [PATCH v2 1/6] mdev: Introduce sha1 based " Parav Pandit
2019-08-29 12:26     ` Yunsheng Lin
2019-08-30  2:27       ` Parav Pandit
2019-08-30  9:17     ` Cornelia Huck
2019-08-30 12:33       ` Parav Pandit
2019-08-30 12:39         ` Cornelia Huck
2019-08-30 12:58           ` Parav Pandit
2019-08-30 14:02             ` Cornelia Huck
2019-08-30 15:45               ` Parav Pandit
2019-09-02 14:46                 ` Cornelia Huck
2019-09-03  3:47                   ` Parav Pandit
2019-08-29 11:19   ` [PATCH v2 2/6] mdev: Make mdev alias unique among all mdevs Parav Pandit
2019-08-29 12:31     ` Yunsheng Lin
2019-08-30 12:40     ` Cornelia Huck
2019-08-30 12:59       ` Parav Pandit
2019-08-29 11:19   ` [PATCH v2 3/6] mdev: Expose mdev alias in sysfs tree Parav Pandit
2019-08-29 11:19   ` [PATCH v2 4/6] mdev: Introduce an API mdev_alias Parav Pandit
2019-08-29 11:19   ` [PATCH v2 5/6] mdev: Update sysfs documentation Parav Pandit
2019-08-30 12:49     ` Cornelia Huck
2019-08-30 13:10       ` Parav Pandit
2019-09-02 14:36         ` Cornelia Huck
2019-09-03  3:53           ` Parav Pandit
2019-08-29 11:19   ` [PATCH v2 6/6] mtty: Optionally support mtty alias Parav Pandit
2019-09-02  4:24 ` [PATCH v3 0/5] Introduce variable length mdev alias Parav Pandit
2019-09-02  4:24   ` [PATCH v3 1/5] mdev: Introduce sha1 based " Parav Pandit
2019-09-17 10:03     ` Cornelia Huck
2019-09-02  4:24   ` [PATCH v3 2/5] mdev: Make mdev alias unique among all mdevs Parav Pandit
2019-09-17 10:04     ` Cornelia Huck
2019-09-02  4:24   ` [PATCH v3 3/5] mdev: Expose mdev alias in sysfs tree Parav Pandit
2019-09-17 10:08     ` Cornelia Huck
2019-09-02  4:24   ` [PATCH v3 4/5] mdev: Introduce an API mdev_alias Parav Pandit
2019-09-17 10:10     ` Cornelia Huck
2019-09-02  4:24   ` [PATCH v3 5/5] mtty: Optionally support mtty alias Parav Pandit
2019-09-09 20:42   ` [PATCH v3 0/5] Introduce variable length mdev alias Parav Pandit
2019-09-11 13:56     ` Alex Williamson
2019-09-11 15:30       ` Parav Pandit
2019-09-11 16:29         ` Cornelia Huck
2019-09-11 16:38         ` Parav Pandit
2019-09-13 21:32           ` Alex Williamson
2019-09-13 23:19             ` Parav Pandit
2019-09-17 10:13   ` Cornelia Huck
2019-09-18 17:15     ` Parav Pandit

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