Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752811AbaGJUAq (ORCPT ); Thu, 10 Jul 2014 16:00:46 -0400 Received: from mail-qg0-f52.google.com ([209.85.192.52]:64585 "EHLO mail-qg0-f52.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752040AbaGJUAo convert rfc822-to-8bit (ORCPT ); Thu, 10 Jul 2014 16:00:44 -0400 MIME-Version: 1.0 X-Originating-IP: [84.208.72.173] In-Reply-To: <53BEB6F9.7030004@6wind.com> References: <1404980258-30853-1-git-send-email-teg@jklm.no> <1404980258-30853-2-git-send-email-teg@jklm.no> <53BEB6F9.7030004@6wind.com> From: Tom Gundersen Date: Thu, 10 Jul 2014 22:00:23 +0200 Message-ID: Subject: Re: [PATCH v7 01/33] net: add name_assign_type netdev attribute To: Nicolas Dichtel Cc: netdev , LKML , David Miller , David Herrmann , Kay Sievers Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jul 10, 2014 at 5:53 PM, Nicolas Dichtel wrote: > Le 10/07/2014 10:17, Tom Gundersen a écrit : > >> 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 >> +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 >> */ > > Nitpicking: there is spaces instead tabs between '2' and the comment. Indeed. Fixed. Thanks. Tom -- 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/