From patchwork Mon Mar 3 22:47:04 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Luis R. Rodriguez" X-Patchwork-Id: 326083 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 EAAA52C014B for ; Tue, 4 Mar 2014 09:48:19 +1100 (EST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755738AbaCCWrj (ORCPT ); Mon, 3 Mar 2014 17:47:39 -0500 Received: from mail-pd0-f178.google.com ([209.85.192.178]:44869 "EHLO mail-pd0-f178.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755721AbaCCWrh (ORCPT ); Mon, 3 Mar 2014 17:47:37 -0500 Received: by mail-pd0-f178.google.com with SMTP id x10so4312255pdj.9 for ; Mon, 03 Mar 2014 14:47:37 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=sender:from:to:cc:subject:date:message-id:in-reply-to:references; bh=gDQ1Y9wndA7UI4344gXUV7tagrzkJlQf6jFlCaesT48=; b=SEkSNW0svTw3fc+Whd3tHaVlxhnhlr4J1CSJsDlmvTYkwenJcdoyB7Tg8dtMOwD+P0 9CNCXvPWjKS/MCzE9aBFYrtSj105w8jbeeVRCzcFsR1tFQlq9MgvosuRuzPimWyorQvu FJCYkHwgeTlg6ZWW0q/vQ3Dj+bf5fY7qBpRmgZWzhbqBNNK0sPjpHDhE7qygo9hO0Pap ky79dpDkplU6H80wyogRQqha8B7SULle37fuiYKj2XEu+wXbE3ZOly75hHM4kW5Og2IB MQ9JcdTYy4JKKqz3j77rvFDdpq+2eEe0Y8e+szUXbwybypFX8Roka7AC6pThCRuzS4UU U8Cw== X-Received: by 10.66.144.200 with SMTP id so8mr2187307pab.15.1393886856964; Mon, 03 Mar 2014 14:47:36 -0800 (PST) Received: from mcgrof@gmail.com (c-24-7-61-223.hsd1.ca.comcast.net. [24.7.61.223]) by mx.google.com with ESMTPSA id iq10sm40376682pbc.14.2014.03.03.14.47.33 for (version=TLSv1 cipher=RC4-SHA bits=128/128); Mon, 03 Mar 2014 14:47:35 -0800 (PST) Received: by mcgrof@gmail.com (sSMTP sendmail emulation); Mon, 03 Mar 2014 14:47:32 -0800 From: "Luis R. Rodriguez" To: netdev@vger.kernel.org Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org, xen-devel@lists.xenproject.org, mcgrof@suse.com, Stephen Hemminger , bridge@lists.linux-foundation.org Subject: [RFC v3 5/6] xen-netback: use a random MAC address and force bridge root block Date: Mon, 3 Mar 2014 14:47:04 -0800 Message-Id: <1393886825-24323-6-git-send-email-mcgrof@do-not-panic.com> X-Mailer: git-send-email 1.8.5.3 In-Reply-To: <1393886825-24323-1-git-send-email-mcgrof@do-not-panic.com> References: <1393886825-24323-1-git-send-email-mcgrof@do-not-panic.com> Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org From: "Luis R. Rodriguez" The purpose of using a static MAC address of FE:FF:FF:FF:FF:FF was to prevent our backend interfaces from being used by the bridge and nominating our interface as a root port on the bridge. This was possible given that the bridge code will use the lowest MAC address for a port once a new interface gets added to the bridge. Sticking to a static MAC address is undesirable for a few reasons: a) using a static MAC address by default on all interfaces can lead to possible conflicts with IPv6 SLAAC and DAD b) The bridge code has a generic bridge port 'root block' feature to allow interfaces to opt out from root bridge port nominations. We want to help stop spreading the use of a high MAC address as a hack to do root port block, and instead get folks to use the proper APIs for this. This modifies xen-netback to use a random MAC address with the xen OUI prefix and enables the bridge root block feature since initialization. Although toggling the root block feature requires the iproute2 bridge tool [0] or sysfs [1] xen-netback users would only need to toggle this off in the case that the net_device is required to be a candidate for root port nomination on the bridge. This is an acceptable compromise in order to avoid the possible conflicts with IPv6 SLAAC and DAD. [0] bridge link set dev vif2.0 root_block off [1] echo 1 > /sys/devices/vif-2-0/net/vif2.0/brport/root_block Cc: Stephen Hemminger Cc: bridge@lists.linux-foundation.org Cc: netdev@vger.kernel.org Cc: linux-kernel@vger.kernel.org Cc: xen-devel@lists.xenproject.org Cc: kvm@vger.kernel.org Signed-off-by: Luis R. Rodriguez --- drivers/net/xen-netback/interface.c | 14 +++++--------- 1 file changed, 5 insertions(+), 9 deletions(-) diff --git a/drivers/net/xen-netback/interface.c b/drivers/net/xen-netback/interface.c index 7669d49..79d71ec 100644 --- a/drivers/net/xen-netback/interface.c +++ b/drivers/net/xen-netback/interface.c @@ -42,6 +42,8 @@ #define XENVIF_QUEUE_LENGTH 32 #define XENVIF_NAPI_WEIGHT 64 +static const u8 xen_oui[3] = { 0x00, 0x16, 0x3e }; + int xenvif_schedulable(struct xenvif *vif) { return netif_running(vif->dev) && netif_carrier_ok(vif->dev); @@ -346,15 +348,9 @@ struct xenvif *xenvif_alloc(struct device *parent, domid_t domid, for (i = 0; i < MAX_PENDING_REQS; i++) vif->mmap_pages[i] = NULL; - /* - * Initialise a dummy MAC address. We choose the numerically - * largest non-broadcast address to prevent the address getting - * stolen by an Ethernet bridge for STP purposes. - * (FE:FF:FF:FF:FF:FF) - */ - memset(dev->dev_addr, 0xFF, ETH_ALEN); - dev->dev_addr[0] &= ~0x01; - + eth_hw_addr_random(dev); + memcpy(dev->dev_addr, xen_oui, 3); + dev->priv_flags |= IFF_BRIDGE_ROOT_BLOCK; netif_napi_add(dev, &vif->napi, xenvif_poll, XENVIF_NAPI_WEIGHT); netif_carrier_off(dev);