Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752655AbaGJT6v (ORCPT ); Thu, 10 Jul 2014 15:58:51 -0400 Received: from mail-gw1-out.broadcom.com ([216.31.210.62]:2089 "EHLO mail-gw1-out.broadcom.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750781AbaGJT6t (ORCPT ); Thu, 10 Jul 2014 15:58:49 -0400 X-IronPort-AV: E=Sophos;i="5.01,639,1400050800"; d="scan'208";a="38904935" Message-ID: <53BEF076.3050705@broadcom.com> Date: Thu, 10 Jul 2014 21:58:46 +0200 From: Arend van Spriel User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.6.0 MIME-Version: 1.0 To: Tom Gundersen , CC: , David Miller , "David Herrmann" , Kay Sievers Subject: Re: [PATCH v7 01/33] net: add name_assign_type netdev attribute References: <1404980258-30853-1-git-send-email-teg@jklm.no> <1404980258-30853-2-git-send-email-teg@jklm.no> In-Reply-To: <1404980258-30853-2-git-send-email-teg@jklm.no> X-Enigmail-Version: 1.5.2 Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10-07-14 10:17, Tom Gundersen wrote: > Based on a patch by David Herrmann. > > The name_assign_type attribute gives hints where the interface name of a > given net-device comes from. These values are currently defined: > NET_NAME_ENUM: > The ifname is provided by the kernel with an enumerated > suffix, typically based on order of discovery. Names may > be reused and unpredictable. > NET_NAME_PREDICTABLE: > The ifname has been assigned by the kernel in a predictable way > that is guaranteed to avoid reuse and always be the same for a > given device. Examples include statically created devices like > the loopback device and names deduced from hardware properties > (including being given explicitly by the firmware). Names > depending on the order of discovery, or in any other way on the > existence of other devices, must not be marked as PREDICTABLE. > NET_NAME_USER: > The ifname was provided by user-space during net-device setup. > NET_NAME_RENAMED: > The net-device has been renamed from userspace. Once this type is set, > it cannot change again. > NET_NAME_UNKNOWN: > This is an internal placeholder to indicate that we yet haven't yet > categorized the name. It will not be exposed to userspace, rather > -EINVAL is returned. > > The aim of these patches is to improve user-space renaming of interfaces. As > a general rule, userspace must rename interfaces to guarantee that names stay > the same every time a given piece of hardware appears (at boot, or when > attaching it). However, there are several situations where userspace should > not perform the renaming, and that depends on both the policy of the local > admin, but crucially also on the nature of the current interface name. > > If an interface was created in repsonse to a userspace request, and userspace > already provided a name, we most probably want to leave that name alone. The > main instance of this is wifi-P2P devices created over nl80211, which currently > have a long-standing bug where they are getting renamed by udev. We label such > names NET_NAME_USER. > > If an interface, unbeknown to us, has already been renamed from userspace, we > most probably want to leave also that alone. This will typically happen when > third-party plugins (for instance to udev, but the interface is generic so could > be from anywhere) renames the interface without informing udev about it. A > typical situation is when you switch root from an installer or an initrd to the > real system and the new instance of udev does not know what happened before > the switch. These types of problems have caused repeated issues in the past. To > solve this, once an interface has been renamed, its name is labelled > NET_NAME_RENAMED. > > In many cases, the kernel is actually able to name interfaces in such a > way that there is no need for userspace to rename them. This is the case when > the enumeration order of devices, or in fact any other (non-parent) device on > the system, can not influence the name of the interface. Examples include > statically created devices, or any naming schemes based on hardware properties > of the interface. In this case the admin may prefer to use the kernel-provided > names, and to make that possible we label such names NET_NAME_PREDICTABLE. > We want the kernel to have tho possibilty of performing predictable interface > naming itself (and exposing to userspace that it has), as the information > necessary for a proper naming scheme for a certain class of devices may not > be exposed to userspace. > > The case where renaming is almost certainly desired, is when the kernel has > given the interface a name using global device enumeration based on order of > discovery (ethX, wlanY, etc). These naming schemes are labelled NET_NAME_ENUM. > > Lastly, a fallback is left as NET_NAME_UNKNOWN, to indicate that a driver has > not yet been ported. This is mostly useful as a transitionary measure, allowing > us to label the various naming schemes bit by bit. > > Signed-off-by: Tom Gundersen > Reviewed-by: David Herrmann > Reviewed-by: Kay Sievers > --- > Documentation/ABI/testing/sysfs-class-net | 11 +++++++++++ > include/linux/netdevice.h | 2 ++ > include/uapi/linux/netdevice.h | 6 ++++++ > net/core/net-sysfs.c | 20 ++++++++++++++++++++ > 4 files changed, 39 insertions(+) > > diff --git a/Documentation/ABI/testing/sysfs-class-net b/Documentation/ABI/testing/sysfs-class-net > index 416c5d5..d34280a 100644 > --- a/Documentation/ABI/testing/sysfs-class-net > +++ b/Documentation/ABI/testing/sysfs-class-net > @@ -1,3 +1,14 @@ > +What: /sys/class/net//name_assign_type > +Date: July 2014 > +KernelVersion: 3.2 Is this a copy&paste error. I guess it will be 3.17+, right? > +Contact: netdev@vger.kernel.org > +Description: > + Indicates the name assignment type. Possible values are: > + 1: enumerated by the kernel, possibly in an unpredictable way > + 2: predictably named by the kernel > + 3: named by userspace > + 4: renamed > + > What: /sys/class/net//addr_assign_type > Date: July 2010 > KernelVersion: 3.2 > diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h > index 66f9a04..551e187 100644 > --- a/include/linux/netdevice.h > +++ b/include/linux/netdevice.h > @@ -1379,6 +1379,8 @@ struct net_device { > struct kset *queues_kset; > #endif > > + unsigned char name_assign_type; > + > bool uc_promisc; > unsigned int promiscuity; > unsigned int allmulti; > diff --git a/include/uapi/linux/netdevice.h b/include/uapi/linux/netdevice.h > index fdfbd1c..82e630a 100644 > --- a/include/uapi/linux/netdevice.h > +++ b/include/uapi/linux/netdevice.h > @@ -37,6 +37,12 @@ > #define INIT_NETDEV_GROUP 0 > > > +/* interface name assignment types (sysfs name_assign_type attribute) */ > +#define NET_NAME_UNKNOWN 0 /* unknown origin (not exposed to userspace) */ > +#define NET_NAME_ENUM 1 /* enumerated by kernel */ > +#define NET_NAME_PREDICTABLE 2 /* predictably named by the kernel */ > +#define NET_NAME_USER 3 /* provided by user-space */ > +#define NET_NAME_RENAMED 4 /* renamed by user-space */ > > /* Media selection options. */ > enum { > diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c > index 1cac29e..7752f2a 100644 > --- a/net/core/net-sysfs.c > +++ b/net/core/net-sysfs.c > @@ -112,6 +112,25 @@ NETDEVICE_SHOW_RO(ifindex, fmt_dec); > NETDEVICE_SHOW_RO(type, fmt_dec); > NETDEVICE_SHOW_RO(link_mode, fmt_dec); > > +static ssize_t format_name_assign_type(const struct net_device *net, char *buf) > +{ > + return sprintf(buf, fmt_dec, net->name_assign_type); > +} > + > +static ssize_t name_assign_type_show(struct device *dev, > + struct device_attribute *attr, > + char *buf) > +{ > + struct net_device *net = to_net_dev(dev); > + ssize_t ret = -EINVAL; > + > + if (net->name_assign_type != NET_NAME_UNKNOWN) > + ret = netdev_show(dev, attr, buf, format_name_assign_type); > + > + return ret; > +} > +static DEVICE_ATTR_RO(name_assign_type); > + > /* use same locking rules as GIFHWADDR ioctl's */ > static ssize_t address_show(struct device *dev, struct device_attribute *attr, > char *buf) > @@ -387,6 +406,7 @@ static struct attribute *net_class_attrs[] = { > &dev_attr_dev_port.attr, > &dev_attr_iflink.attr, > &dev_attr_ifindex.attr, > + &dev_attr_name_assign_type.attr, > &dev_attr_addr_assign_type.attr, > &dev_attr_addr_len.attr, > &dev_attr_link_mode.attr, > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/