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authorVladimir Oltean <vladimir.oltean@nxp.com>2021-07-28 21:27:47 +0300
committerDavid S. Miller <davem@davemloft.net>2021-07-28 20:25:50 +0100
commitb4454bc6a0fbf2f9edcddd08862175085b990856 (patch)
tree4a3d12780403d781ed41a55cc8d7354fe6cb5b16 /net/bridge/br_private.h
parent1159da6410a382000528008126b50c7320798434 (diff)
net: bridge: switchdev: replay the entire FDB for each port
Currently when a switchdev port joins a bridge, we replay all FDB entries pointing towards that port or towards the bridge. However, this is insufficient in certain situations: (a) DSA, through its assisted_learning_on_cpu_port logic, snoops dynamically learned FDB entries on foreign interfaces. These are FDB entries that are pointing neither towards the newly joined switchdev port, nor towards the bridge. So these addresses would be missed when joining a bridge where a foreign interface has already learned some addresses, and they would also linger on if the DSA port leaves the bridge before the foreign interface forgets them. None of this happens if we replay the entire FDB when the port joins. (b) There is a desire to treat local FDB entries on a port (i.e. the port's termination MAC address) identically to FDB entries pointing towards the bridge itself. More details on the reason behind this in the next patch. The point is that this cannot be done given the current structure of br_fdb_replay() in this situation: ip link set swp0 master br0 # br0 inherits its MAC address from swp0 ip link set swp1 master br0 What is desirable is that when swp1 joins the bridge, br_fdb_replay() also notifies swp1 of br0's MAC address, but this won't in fact happen because the MAC address of br0 does not have fdb->dst == NULL (it doesn't point towards the bridge), but it has fdb->dst == swp0. So our current logic makes it impossible for that address to be replayed. But if we dump the entire FDB instead of just the entries with fdb->dst == swp1 and fdb->dst == NULL, then the inherited MAC address of br0 will be replayed too, which is what we need. A natural question arises: say there is an FDB entry to be replayed, like a MAC address dynamically learned on a foreign interface that belongs to a bridge where no switchdev port has joined yet. If 10 switchdev ports belonging to the same driver join this bridge, one by one, won't every port get notified 10 times of the foreign FDB entry, amounting to a total of 100 notifications for this FDB entry in the switchdev driver? Well, yes, but this is where the "void *ctx" argument for br_fdb_replay is useful: every port of the switchdev driver is notified whenever any other port requests an FDB replay, but because the replay was initiated by a different port, its context is different from the initiating port's context, so it ignores those replays. So the foreign FDB entry will be installed only 10 times, once per port. This is done so that the following 4 code paths are always well balanced: (a) addition of foreign FDB entry is replayed when port joins bridge (b) deletion of foreign FDB entry is replayed when port leaves bridge (c) addition of foreign FDB entry is notified to all ports currently in bridge (c) deletion of foreign FDB entry is notified to all ports currently in bridge Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/bridge/br_private.h')
-rw-r--r--net/bridge/br_private.h4
1 files changed, 2 insertions, 2 deletions
diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h
index f2d34ea1ea37..c939631428b9 100644
--- a/net/bridge/br_private.h
+++ b/net/bridge/br_private.h
@@ -777,8 +777,8 @@ int br_fdb_external_learn_del(struct net_bridge *br, struct net_bridge_port *p,
bool swdev_notify);
void br_fdb_offloaded_set(struct net_bridge *br, struct net_bridge_port *p,
const unsigned char *addr, u16 vid, bool offloaded);
-int br_fdb_replay(const struct net_device *br_dev, const struct net_device *dev,
- const void *ctx, bool adding, struct notifier_block *nb);
+int br_fdb_replay(const struct net_device *br_dev, const void *ctx, bool adding,
+ struct notifier_block *nb);
/* br_forward.c */
enum br_pkt_type {