From d0cf3c6bf15af1eaad945fc57f1d9b0ab98d6d4b Mon Sep 17 00:00:00 2001 From: Ben Pfaff Date: Tue, 17 Jan 2012 11:15:49 -0800 Subject: [PATCH 1/1] datapath: Enforce mutual exclusion between bridge and brcompat_mod. MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit In kernels 2.6.36, Open vSwitch can (and does) safely coexist with the Linux bridge module, but it does not make sense to load both bridge and brcompat_mod at the same time. Until now, nothing has prevented both from loading; when they both load, confusion (at best) results. This fixes the problem by enforcing mutual exclusion. Bug #9226. Launchpad bug #917309. Reported-by: Rogério Vinhal Nunes Signed-off-by: Ben Pfaff Acked-by: Jesse Gross --- datapath/brcompat.c | 12 ++++++++++-- datapath/compat.h | 22 +++++++++++++++++++++- datapath/vport-netdev.c | 21 ++++++--------------- 3 files changed, 37 insertions(+), 18 deletions(-) diff --git a/datapath/brcompat.c b/datapath/brcompat.c index f9d008399..176074348 100644 --- a/datapath/brcompat.c +++ b/datapath/brcompat.c @@ -1,6 +1,5 @@ /* - * Copyright (c) 2009, 2011 Nicira Networks. - * Distributed under the terms of the GNU GPL version 2. + * Copyright (c) 2007-2012 Nicira Networks. * * Significant portions of this file may be copied from parts of the Linux * kernel, by Linus Torvalds and others. @@ -548,3 +547,12 @@ module_exit(brc_cleanup); MODULE_DESCRIPTION("Open vSwitch bridge compatibility"); MODULE_AUTHOR("Nicira Networks"); MODULE_LICENSE("GPL"); + +#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,36) +/* + * In kernels 2.6.36 and later, Open vSwitch can safely coexist with + * the Linux bridge module, but it does not make sense to load both bridge and + * brcompat_mod, so this prevents it. + */ +BRIDGE_MUTUAL_EXCLUSION; +#endif diff --git a/datapath/compat.h b/datapath/compat.h index c484a5d72..8dc52a95f 100644 --- a/datapath/compat.h +++ b/datapath/compat.h @@ -1,5 +1,5 @@ /* - * Copyright (c) 2011 Nicira Networks. + * Copyright (c) 2011, 2012 Nicira Networks. * Distributed under the terms of the GNU GPL version 2. * * Significant portions of this file may be copied from parts of the Linux @@ -36,4 +36,24 @@ static inline int CHECK_NUL_STRING(struct nlattr *attr, int maxlen) } #endif /* !HAVE_NLA_NUL_STRING */ +/* + * Enforces mutual exclusion with the Linux bridge module, by declaring and + * exporting br_should_route_hook. Because the bridge module also exports the + * same symbol, the module loader will refuse to load both modules at the same + * time (e.g. "bridge: exports duplicate symbol br_should_route_hook (owned by + * openvswitch_mod)"). + * + * Before Linux 2.6.36, Open vSwitch cannot safely coexist with the Linux + * bridge module, so openvswitch_mod uses this macro in those versions. In + * Linux 2.6.36 and later, Open vSwitch can coexist with the bridge module, but + * it makes no sense to load both bridge and brcompat_mod, so brcompat_mod uses + * this macro in those versions. + * + * The use of "typeof" here avoids the need to track changes in the type of + * br_should_route_hook over various kernel versions. + */ +#define BRIDGE_MUTUAL_EXCLUSION \ + typeof(br_should_route_hook) br_should_route_hook; \ + EXPORT_SYMBOL(br_should_route_hook) + #endif /* compat.h */ diff --git a/datapath/vport-netdev.c b/datapath/vport-netdev.c index 3239135f0..ddd77d06a 100644 --- a/datapath/vport-netdev.c +++ b/datapath/vport-netdev.c @@ -1,5 +1,5 @@ /* - * Copyright (c) 2010, 2011 Nicira Networks. + * Copyright (c) 2010, 2011, 2012 Nicira Networks. * Distributed under the terms of the GNU GPL version 2. * * Significant portions of this file may be copied from parts of the Linux @@ -423,19 +423,10 @@ const struct vport_ops netdev_vport_ops = { #if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,36) /* - * In kernels earlier than 2.6.36, Open vSwitch cannot safely coexist with - * the Linux bridge module on any released version of Linux, because there - * is only a single bridge hook function and only a single br_port member - * in struct net_device. - * - * Declaring and exporting this symbol enforces mutual exclusion. The bridge - * module also exports the same symbol, so the module loader will refuse to - * load both modules at the same time (e.g. "bridge: exports duplicate symbol - * br_should_route_hook (owned by openvswitch_mod)"). - * - * The use of "typeof" here avoids the need to track changes in the type of - * br_should_route_hook over various kernel versions. + * In kernels earlier than 2.6.36, Open vSwitch cannot safely coexist with the + * Linux bridge module, because there is only a single bridge hook function and + * only a single br_port member in struct net_device, so this prevents loading + * both bridge and openvswitch_mod at the same time. */ -typeof(br_should_route_hook) br_should_route_hook; -EXPORT_SYMBOL(br_should_route_hook); +BRIDGE_MUTUAL_EXCLUSION; #endif -- 2.43.0