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=-0.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham 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 AC56AC48BD7 for ; Thu, 27 Jun 2019 17:48:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 856A820644 for ; Thu, 27 Jun 2019 17:48:15 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=netronome-com.20150623.gappssmtp.com header.i=@netronome-com.20150623.gappssmtp.com header.b="RZryFpJs" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726749AbfF0RsO (ORCPT ); Thu, 27 Jun 2019 13:48:14 -0400 Received: from mail-qk1-f194.google.com ([209.85.222.194]:43423 "EHLO mail-qk1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726557AbfF0RsO (ORCPT ); Thu, 27 Jun 2019 13:48:14 -0400 Received: by mail-qk1-f194.google.com with SMTP id m14so2464173qka.10 for ; Thu, 27 Jun 2019 10:48:13 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=netronome-com.20150623.gappssmtp.com; s=20150623; h=date:from:to:cc:subject:message-id:in-reply-to:references :organization:mime-version:content-transfer-encoding; bh=P2et0OJE+IoV88xr/ln/SEgjBIDStaX2uEFJJ+kOQzY=; b=RZryFpJsuiniMjOJU7bTkSTCdkFW3BxvyAuB5EJcSHZ8HPW3NbGKm26EvdgBjuU+7E ZTuhlncIGZPA1EFjyQ/VG9ALnmpsYOyNlXiusafH94jEi6I/1ls9yWtftAKj7xB2tdEs QUJAb95D2Zv+cl89YpSagFdU5GbkCMl/1HgsRlKdtP70x1gNtNIcTfVqYa+63Smwiy7w gKB6Htwumbo08dafUfCu9xY3e6JXNS30VHJN4FyAUnIFH3e5t2OUSzYVDNcpzO4hrW5O h0Cci831eg+rJtZDw4kl8bTdC89cjC0luR0R8tM6RfzsOQZ7JSVR6yKu+wMs6ETRLtKB 2iJA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:in-reply-to :references:organization:mime-version:content-transfer-encoding; bh=P2et0OJE+IoV88xr/ln/SEgjBIDStaX2uEFJJ+kOQzY=; b=Cnz8CRVSpN9fhRbS/c9Px1Et0RaxIzKOHaK24Goqqd1TgZoRu7iODuk7XRWmRFXUuJ xj3olQVa8XTA/FH+4awBlTAKjZsuwYiuRkpZttq/RkpdL7IYUf16IY6T+iy2yCdS9Gt9 QP/uf/2i+ha455xPKdTOv4M7pm5+zV8aKEfHgYi2ugIEQo9b4hRp5C8oF2QxpVqiR8tC D654OZ89ocTJ1wGJ6HWlmSh/rv1/sGCcMAmC2O3vgj91n/8faxMguWth4EZHRyGGobJh cR8UXDOBHJl9RJMzGyP+afvj6e41iNPOh4+1beRalCsCedpSRzYihFm3wgV2qQhNle6r bxBg== X-Gm-Message-State: APjAAAXgm2LecPCzYPfqZZYkjpKYDuXmqixzae0+cl7HIBao9mmx3xB7 FSAI3VidnC46k8MEnDmExZTXBg== X-Google-Smtp-Source: APXvYqxmRxIn7X6/uKZiMScZoXpsjCN7ns3p99ujN4tW/GkOdaIgebSptAuajIG/QI//Q3Vqmz+gBw== X-Received: by 2002:a37:9481:: with SMTP id w123mr4435445qkd.319.1561657693405; Thu, 27 Jun 2019 10:48:13 -0700 (PDT) Received: from cakuba.netronome.com ([66.60.152.14]) by smtp.gmail.com with ESMTPSA id v17sm1355957qtc.23.2019.06.27.10.48.12 (version=TLS1_3 cipher=AEAD-AES256-GCM-SHA384 bits=256/256); Thu, 27 Jun 2019 10:48:13 -0700 (PDT) Date: Thu, 27 Jun 2019 10:48:08 -0700 From: Jakub Kicinski To: Jiri Pirko Cc: netdev@vger.kernel.org, davem@davemloft.net, sthemmin@microsoft.com, dsahern@gmail.com, mlxsw@mellanox.com Subject: Re: [RFC] longer netdev names proposal Message-ID: <20190627104808.1404049a@cakuba.netronome.com> In-Reply-To: <20190627094327.GF2424@nanopsycho> References: <20190627094327.GF2424@nanopsycho> Organization: Netronome Systems, Ltd. MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Thu, 27 Jun 2019 11:43:27 +0200, Jiri Pirko wrote: > Hi all. > > In the past, there was repeatedly discussed the IFNAMSIZ (16) limit for > netdevice name length. Now when we have PF and VF representors > with port names like "pfXvfY", it became quite common to hit this limit: > 0123456789012345 > enp131s0f1npf0vf6 > enp131s0f1npf0vf22 > > Since IFLA_NAME is just a string, I though it might be possible to use > it to carry longer names as it is. However, the userspace tools, like > iproute2, are doing checks before print out. So for example in output of > "ip addr" when IFLA_NAME is longer than IFNAMSIZE, the netdevice is > completely avoided. > > So here is a proposal that might work: > 1) Add a new attribute IFLA_NAME_EXT that could carry names longer than > IFNAMSIZE, say 64 bytes. The max size should be only defined in kernel, > user should be prepared for any string size. > 2) Add a file in sysfs that would indicate that NAME_EXT is supported by > the kernel. > 3) Udev is going to look for the sysfs indication file. In case when > kernel supports long names, it will do rename to longer name, setting > IFLA_NAME_EXT. If not, it does what it does now - fail. > 4) There are two cases that can happen during rename: > A) The name is shorter than IFNAMSIZ > -> both IFLA_NAME and IFLA_NAME_EXT would contain the same string: > original IFLA_NAME = eth0 > original IFLA_NAME_EXT = eth0 > renamed IFLA_NAME = enp5s0f1npf0vf1 > renamed IFLA_NAME_EXT = enp5s0f1npf0vf1 > B) The name is longer tha IFNAMSIZ > -> IFLA_NAME would contain the original one, IFLA_NAME_EXT would > contain the new one: > original IFLA_NAME = eth0 > original IFLA_NAME_EXT = eth0 > renamed IFLA_NAME = eth0 > renamed IFLA_NAME_EXT = enp131s0f1npf0vf22 I think B is the only way, A risks duplicate IFLA_NAMEs over ioctl, right? And maybe there is some crazy application out there which mixes netlink and ioctl. I guess it's not worse than status quo, given that today renames will fail and we will either get truncated names or eth0s.. > This would allow the old tools to work with "eth0" and the new > tools would work with "enp131s0f1npf0vf22". In sysfs, there would > be symlink from one name to another. > > Also, there might be a warning added to kernel if someone works > with IFLA_NAME that the userspace tool should be upgraded. > > Eventually, only IFLA_NAME_EXT is going to be used by everyone. > > I'm aware there are other places where similar new attribute > would have to be introduced too (ip rule for example). > I'm not saying this is a simple work. > > Question is what to do with the ioctl api (get ifindex etc). I would > probably leave it as is and push tools to use rtnetlink instead. > > Any ideas why this would not work? Any ideas how to solve this > differently? Since we'd have to update all user space to make use of the new names I'd be tempted to move to a more structured device identification. 5: enp131s0f1npf0vf6: ... vs: 5: eth5 (parent enp131s0f1 pf 0 vf 6 peer X*): ... * ;) And allow filtering/selection of device based on more attributes than just name and ifindex. In practice in container workloads, for example, the names are already very much insufficient to identify the device. Refocusing on attributes is probably a big effort and not that practical for traditional CLI users? IDK Anyway, IMHO your scheme is strictly better than status quo.