From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 93E1DC3A5A6 for ; Tue, 27 Aug 2019 10:47:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6D7782189D for ; Tue, 27 Aug 2019 10:47:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728834AbfH0KrN (ORCPT ); Tue, 27 Aug 2019 06:47:13 -0400 Received: from mx1.redhat.com ([209.132.183.28]:45884 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725793AbfH0KrN (ORCPT ); Tue, 27 Aug 2019 06:47:13 -0400 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 59B4E8AC6E1; Tue, 27 Aug 2019 10:47:13 +0000 (UTC) Received: from gondolin (dhcp-192-222.str.redhat.com [10.33.192.222]) by smtp.corp.redhat.com (Postfix) with ESMTP id 2BEAF6012A; Tue, 27 Aug 2019 10:47:09 +0000 (UTC) Date: Tue, 27 Aug 2019 12:47:06 +0200 From: Cornelia Huck To: Parav Pandit Cc: alex.williamson@redhat.com, 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 3/4] mdev: Expose mdev alias in sysfs tree Message-ID: <20190827124706.7e726794.cohuck@redhat.com> In-Reply-To: <20190826204119.54386-4-parav@mellanox.com> References: <20190826204119.54386-1-parav@mellanox.com> <20190826204119.54386-4-parav@mellanox.com> Organization: Red Hat GmbH MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.6.2 (mx1.redhat.com [10.5.110.69]); Tue, 27 Aug 2019 10:47:13 +0000 (UTC) Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Mon, 26 Aug 2019 15:41:18 -0500 Parav Pandit 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 > --- > 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, > };