Messages in this thread | | | Date | Tue, 27 Aug 2019 12:47:06 +0200 | From | Cornelia Huck <> | Subject | Re: [PATCH 3/4] mdev: Expose mdev alias in sysfs tree |
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On Mon, 26 Aug 2019 15:41:18 -0500 Parav Pandit <parav@mellanox.com> wrote:
> Expose mdev alias as string in a sysfs tree so that such attribute can > be used to generate netdevice name by systemd/udev or can be used to > match other kernel objects based on the alias of the mdev.
What about
"Expose the optional alias for an mdev device as a sysfs attribute. This way, userspace tools such as udev may make use of the alias, for example to create a netdevice name for the mdev."
> > Signed-off-by: Parav Pandit <parav@mellanox.com> > --- > drivers/vfio/mdev/mdev_sysfs.c | 13 +++++++++++++
I think the documentation should be updated as well.
> 1 file changed, 13 insertions(+) > > diff --git a/drivers/vfio/mdev/mdev_sysfs.c b/drivers/vfio/mdev/mdev_sysfs.c > index 43afe0e80b76..59f4e3cc5233 100644 > --- a/drivers/vfio/mdev/mdev_sysfs.c > +++ b/drivers/vfio/mdev/mdev_sysfs.c > @@ -246,7 +246,20 @@ static ssize_t remove_store(struct device *dev, struct device_attribute *attr, > > static DEVICE_ATTR_WO(remove); > > +static ssize_t alias_show(struct device *device, > + struct device_attribute *attr, char *buf) > +{ > + struct mdev_device *dev = mdev_from_dev(device); > + > + if (!dev->alias) > + return -EOPNOTSUPP;
I'm wondering how to make this consumable by userspace in the easiest way. - As you do now (userspace gets an error when trying to read)? - Returning an empty value (nothing to see here, move along)? - Or not creating the attribute at all? That would match what userspace sees on older kernels, so it needs to be able to deal with that anyway.
> + > + return sprintf(buf, "%s\n", dev->alias); > +} > +static DEVICE_ATTR_RO(alias); > + > static const struct attribute *mdev_device_attrs[] = { > + &dev_attr_alias.attr, > &dev_attr_remove.attr, > NULL, > };
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