From patchwork Sat Oct 8 02:04:33 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jarod Wilson X-Patchwork-Id: 679791 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 3srV8K3V4xz9s3s for ; Sat, 8 Oct 2016 13:05:05 +1100 (AEDT) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933126AbcJHCEw (ORCPT ); Fri, 7 Oct 2016 22:04:52 -0400 Received: from mx1.redhat.com ([209.132.183.28]:43432 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933040AbcJHCEs (ORCPT ); Fri, 7 Oct 2016 22:04:48 -0400 Received: from int-mx11.intmail.prod.int.phx2.redhat.com (int-mx11.intmail.prod.int.phx2.redhat.com [10.5.11.24]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 621802D1262; Sat, 8 Oct 2016 02:04:48 +0000 (UTC) Received: from hp-dl360pgen8-07.khw.lab.eng.bos.redhat.com (hp-dl360pgen8-07.khw.lab.eng.bos.redhat.com [10.16.184.47]) by int-mx11.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id u9824go1024348; Fri, 7 Oct 2016 22:04:47 -0400 From: Jarod Wilson To: linux-kernel@vger.kernel.org Cc: Jarod Wilson , netdev@vger.kernel.org Subject: [PATCH v3 net-next 1/2] net: centralize net_device min/max MTU checking Date: Fri, 7 Oct 2016 22:04:33 -0400 Message-Id: <20161008020434.9691-2-jarod@redhat.com> In-Reply-To: <20161008020434.9691-1-jarod@redhat.com> References: <20161002.224322.740109807229746275.davem@davemloft.net> <20161008020434.9691-1-jarod@redhat.com> X-Scanned-By: MIMEDefang 2.68 on 10.5.11.24 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.26]); Sat, 08 Oct 2016 02:04:48 +0000 (UTC) Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org While looking into an MTU issue with sfc, I started noticing that almost every NIC driver with an ndo_change_mtu function implemented almost exactly the same range checks, and in many cases, that was the only practical thing their ndo_change_mtu function was doing. Quite a few drivers have either 68, 64, 60 or 46 as their minimum MTU value checked, and then various sizes from 1500 to 65535 for their maximum MTU value. We can remove a whole lot of redundant code here if we simple store min_mtu and max_mtu in net_device, and check against those in net/core/dev.c's dev_set_mtu(). In theory, there should be zero functional change with this patch, it just puts the infrastructure in place. Subsequent patches will attempt to start using said infrastructure, with theoretically zero change in functionality. CC: netdev@vger.kernel.org Signed-off-by: Jarod Wilson --- v3: retain new_mtu < 0 check to prevent integral promotions, as pointed out by Jakub Sitnicki. include/linux/netdevice.h | 4 ++++ net/core/dev.c | 13 +++++++++++-- 2 files changed, 15 insertions(+), 2 deletions(-) diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h index 136ae6bb..fbdf923 100644 --- a/include/linux/netdevice.h +++ b/include/linux/netdevice.h @@ -1506,6 +1506,8 @@ enum netdev_priv_flags { * @if_port: Selectable AUI, TP, ... * @dma: DMA channel * @mtu: Interface MTU value + * @min_mtu: Interface Minimum MTU value + * @max_mtu: Interface Maximum MTU value * @type: Interface hardware type * @hard_header_len: Maximum hardware header length. * @@ -1726,6 +1728,8 @@ struct net_device { unsigned char dma; unsigned int mtu; + unsigned int min_mtu; + unsigned int max_mtu; unsigned short type; unsigned short hard_header_len; diff --git a/net/core/dev.c b/net/core/dev.c index f1fe26f..f376639 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -6499,9 +6499,18 @@ int dev_set_mtu(struct net_device *dev, int new_mtu) if (new_mtu == dev->mtu) return 0; - /* MTU must be positive. */ - if (new_mtu < 0) + /* MTU must be positive, and in range */ + if (new_mtu < 0 || new_mtu < dev->min_mtu) { + net_err_ratelimited("%s: Invalid MTU %d requested, hw min %d\n", + dev->name, new_mtu, dev->min_mtu); return -EINVAL; + } + + if (dev->max_mtu > 0 && new_mtu > dev->max_mtu) { + net_err_ratelimited("%s: Invalid MTU %d requested, hw max %d\n", + dev->name, new_mtu, dev->min_mtu); + return -EINVAL; + } if (!netif_device_present(dev)) return -ENODEV;