Luis R. Rodriguez
2014-Mar-03 22:47 UTC
[RFC v3 4/6] bridge: enable root block during device registration
From: "Luis R. Rodriguez" <mcgrof@suse.com>
root block support was added via 1007dd1a on v3.8 but toggling
this flag is only allowed after a device has been registered and
added to a bridge as its a bridge *port* primitive, not a *net_device*
feature. There are work arounds possible to account for the lack
of netlink tools to toggle root_block, such as using the root_block
syfs attribute [0] or using udev / the driver to set the MAC address
to something high such as FE:FF:FF:FF:FF:FF, but neither of these
ensure root block is respected _from_the_start_ through device
initialization.
In order to support the root_block feature from the start since device
initialization and in order to avoid having to require userspace
work arounds to existing deployments this exposes a private
net_device flag which enables drivers that know they want to
start with the root_block feature enabled form the start. The
only caveat with this is topologies that require STP or non-root
will either have to use sysfs [0] or netlink tools like the
iproute2 bridge util to toggle the flag off after initialization.
This is an accepted compromise.
This flag is required given that ndo_add_slave() currently does not
allow specifying any other parameters other than the net_device. We
could extend this but in order to do that properly we'd need to
evaluate all other types of master device implementations.
[0] echo 1 > /sys/devices/vif-2-0/net/vif2.0/brport/root_block
Cc: Stephen Hemminger <stephen@networkplumber.org>
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 <mcgrof@suse.com>
---
include/linux/netdevice.h | 7 +++++++
net/bridge/br_if.c | 2 ++
2 files changed, 9 insertions(+)
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 1a86948..b17643a 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -1181,6 +1181,11 @@ struct net_device_ops {
* @IFF_LIVE_ADDR_CHANGE: device supports hardware address
* change when it's running
* @IFF_MACVLAN: Macvlan device
+ * @IFF_BRIDGE_ROOT_BLOCK: don't consider this net_device for root port
+ * when this interface is added to a bridge. This makes use of the
+ * root_block mechanism but since its a bridge port primitive this
+ * flag can be used to instantiate the preference to have root block
+ * enabled from the start since initialization.
*/
enum netdev_priv_flags {
IFF_802_1Q_VLAN = 1<<0,
@@ -1205,6 +1210,7 @@ enum netdev_priv_flags {
IFF_SUPP_NOFCS = 1<<19,
IFF_LIVE_ADDR_CHANGE = 1<<20,
IFF_MACVLAN = 1<<21,
+ IFF_BRIDGE_ROOT_BLOCK = 1<<22,
};
#define IFF_802_1Q_VLAN IFF_802_1Q_VLAN
@@ -1229,6 +1235,7 @@ enum netdev_priv_flags {
#define IFF_SUPP_NOFCS IFF_SUPP_NOFCS
#define IFF_LIVE_ADDR_CHANGE IFF_LIVE_ADDR_CHANGE
#define IFF_MACVLAN IFF_MACVLAN
+#define IFF_BRIDGE_ROOT_BLOCK IFF_BRIDGE_ROOT_BLOCK
/*
* The DEVICE structure.
diff --git a/net/bridge/br_if.c b/net/bridge/br_if.c
index 54d207d..4bee748 100644
--- a/net/bridge/br_if.c
+++ b/net/bridge/br_if.c
@@ -228,6 +228,8 @@ static struct net_bridge_port *new_nbp(struct net_bridge
*br,
br_init_port(p);
p->state = BR_STATE_DISABLED;
br_stp_port_timer_init(p);
+ if (dev->priv_flags & IFF_BRIDGE_ROOT_BLOCK)
+ p->flags |= BR_ROOT_BLOCK;
br_multicast_add_port(p);
return p;
--
1.9.0