bridge: switchdev: Add forward mark support for stacked devices

switchdev_port_fwd_mark_set() is used to set the 'offload_fwd_mark' of
port netdevs so that packets being flooded by the device won't be
flooded twice.

It works by assigning a unique identifier (the ifindex of the first
bridge port) to bridge ports sharing the same parent ID. This prevents
packets from being flooded twice by the same switch, but will flood
packets through bridge ports belonging to a different switch.

This method is problematic when stacked devices are taken into account,
such as VLANs. In such cases, a physical port netdev can have upper
devices being members in two different bridges, thus requiring two
different 'offload_fwd_mark's to be configured on the port netdev, which
is impossible.

The main problem is that packet and netdev marking is performed at the
physical netdev level, whereas flooding occurs between bridge ports,
which are not necessarily port netdevs.

Instead, packet and netdev marking should really be done in the bridge
driver with the switch driver only telling it which packets it already
forwarded. The bridge driver will mark such packets using the mark
assigned to the ingress bridge port and will prevent the packet from
being forwarded through any bridge port sharing the same mark (i.e.
having the same parent ID).

Remove the current switchdev 'offload_fwd_mark' implementation and
instead implement the proposed method. In addition, make rocker - the
sole user of the mark - use the proposed method.

Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 0 insertions, 85 deletions

diff --git a/net/switchdev/switchdev.c b/net/switchdev/switchdev.c
index 2c683f24d557..1031a0327fff 100644
--- a/net/switchdev/switchdev.c
+++ b/net/switchdev/switchdev.c
@@ -1305,88 +1305,3 @@ bool switchdev_port_same_parent_id(struct net_device *a,
         return netdev_phys_item_id_same(&a_attr.u.ppid, &b_attr.u.ppid);
 }
 EXPORT_SYMBOL_GPL(switchdev_port_same_parent_id);
-
-static u32 switchdev_port_fwd_mark_get(struct net_device *dev,
-                                       struct net_device *group_dev)
-{
-        struct net_device *lower_dev;
-        struct list_head *iter;
-
-        netdev_for_each_lower_dev(group_dev, lower_dev, iter) {
-                if (lower_dev == dev)
-                        continue;
-                if (switchdev_port_same_parent_id(dev, lower_dev))
-                        return lower_dev->offload_fwd_mark;
-                return switchdev_port_fwd_mark_get(dev, lower_dev);
-        }
-
-        return dev->ifindex;
-}
-
-static void switchdev_port_fwd_mark_reset(struct net_device *group_dev,
-                                          u32 old_mark, u32 *reset_mark)
-{
-        struct net_device *lower_dev;
-        struct list_head *iter;
-
-        netdev_for_each_lower_dev(group_dev, lower_dev, iter) {
-                if (lower_dev->offload_fwd_mark == old_mark) {
-                        if (!*reset_mark)
-                                *reset_mark = lower_dev->ifindex;
-                        lower_dev->offload_fwd_mark = *reset_mark;
-                }
-                switchdev_port_fwd_mark_reset(lower_dev, old_mark, reset_mark);
-        }
-}
-
-/**
- *      switchdev_port_fwd_mark_set - Set port offload forwarding mark
- *
- *      @dev: port device
- *      @group_dev: containing device
- *      @joining: true if dev is joining group; false if leaving group
- *
- *      An ungrouped port's offload mark is just its ifindex.  A grouped
- *      port's (member of a bridge, for example) offload mark is the ifindex
- *      of one of the ports in the group with the same parent (switch) ID.
- *      Ports on the same device in the same group will have the same mark.
- *
- *      Example:
- *
- *              br0             ifindex=9
- *                sw1p1         ifindex=2       mark=2
- *                sw1p2         ifindex=3       mark=2
- *                sw2p1         ifindex=4       mark=5
- *                sw2p2         ifindex=5       mark=5
- *
- *      If sw2p2 leaves the bridge, we'll have:
- *
- *              br0             ifindex=9
- *                sw1p1         ifindex=2       mark=2
- *                sw1p2         ifindex=3       mark=2
- *                sw2p1         ifindex=4       mark=4
- *              sw2p2           ifindex=5       mark=5
- */
-void switchdev_port_fwd_mark_set(struct net_device *dev,
-                                 struct net_device *group_dev,
-                                 bool joining)
-{
-        u32 mark = dev->ifindex;
-        u32 reset_mark = 0;
-
-        if (group_dev) {
-                ASSERT_RTNL();
-                if (joining)
-                        mark = switchdev_port_fwd_mark_get(dev, group_dev);
-                else if (dev->offload_fwd_mark == mark)
-                        /* Ohoh, this port was the mark reference port,
-                         * but it's leaving the group, so reset the
-                         * mark for the remaining ports in the group.
-                         */
-                        switchdev_port_fwd_mark_reset(group_dev, mark,
-                                                      &reset_mark);
-        }
-
-        dev->offload_fwd_mark = mark;
-}
-EXPORT_SYMBOL_GPL(switchdev_port_fwd_mark_set);