From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jarod Wilson Subject: [PATCH net-next 1/2] net: centralize net_device min/max MTU checking Date: Mon, 12 Sep 2016 16:11:05 -0400 Message-ID: <20160912201106.47837-2-jarod@redhat.com> References: <20160912201106.47837-1-jarod@redhat.com> Cc: Jarod Wilson , "David S. Miller" , netdev@vger.kernel.org To: linux-kernel@vger.kernel.org Return-path: Received: from mx1.redhat.com ([209.132.183.28]:35354 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752008AbcILUMX (ORCPT ); Mon, 12 Sep 2016 16:12:23 -0400 In-Reply-To: <20160912201106.47837-1-jarod@redhat.com> Sender: netdev-owner@vger.kernel.org List-ID: 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: "David S. Miller" CC: netdev@vger.kernel.org Signed-off-by: Jarod Wilson --- include/linux/netdevice.h | 4 ++++ net/core/dev.c | 12 ++++++++++-- 2 files changed, 14 insertions(+), 2 deletions(-) diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h index 67bb978..e466949 100644 --- a/include/linux/netdevice.h +++ b/include/linux/netdevice.h @@ -1490,6 +1490,8 @@ 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. * @@ -1710,6 +1712,8 @@ 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 34b5322..9785588 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -6473,9 +6473,17 @@ 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) + if (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; -- 2.10.0