netdev - RE: [PATCH v2 2/6] mdev: Make mdev alias unique among all mdevs

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Date:   Fri, 30 Aug 2019 12:59:49 +0000
From:   Parav Pandit <parav@...lanox.com>
To:     Cornelia Huck <cohuck@...hat.com>
CC:     "alex.williamson@...hat.com" <alex.williamson@...hat.com>,
        Jiri Pirko <jiri@...lanox.com>,
        "kwankhede@...dia.com" <kwankhede@...dia.com>,
        "davem@...emloft.net" <davem@...emloft.net>,
        "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: RE: [PATCH v2 2/6] mdev: Make mdev alias unique among all mdevs



> -----Original Message-----
> From: Cornelia Huck <cohuck@...hat.com>
> Sent: Friday, August 30, 2019 6:11 PM
> To: Parav Pandit <parav@...lanox.com>
> Cc: alex.williamson@...hat.com; Jiri Pirko <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 v2 2/6] mdev: Make mdev alias unique among all mdevs
> 
> On Thu, 29 Aug 2019 06:19:00 -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>
> >
> > ---
> > Changelog:
> > v1->v2:
> >  - Moved alias NULL check at beginning
> > 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 3bdff0469607..c9bf2ac362b9
> > 100644
> > --- a/drivers/vfio/mdev/mdev_core.c
> > +++ b/drivers/vfio/mdev/mdev_core.c
> > @@ -388,6 +388,13 @@ int mdev_device_create(struct kobject *kobj, struct
> device *dev,
> >  			ret = -EEXIST;
> >  			goto mdev_fail;
> >  		}
> > +		if (alias && tmp->alias && strcmp(alias, tmp->alias) == 0) {
> > +			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);
> 
> Any reason not to merge this into the first patch?
No. It surely can be merged. Its easy to start with smaller patches instead of splitting. :-)
Doing uniqueness comparison was easy to split as independent functionality, so did as 2nd patch.
But either way is ok.