On Fri, Mar 19, 2021 at 01:18, Vladimir Oltean <olteanv@xxxxxxxxx> wrote: > From: Vladimir Oltean <vladimir.oltean@xxxxxxx> > > When a DSA port joins a LAG that already had an FDB entry pointing to it: > > ip link set bond0 master br0 > bridge fdb add dev bond0 00:01:02:03:04:05 master static > ip link set swp0 master bond0 > > the DSA port will have no idea that this FDB entry is there, because it > missed the switchdev event emitted at its creation. > > Ido Schimmel pointed this out during a discussion about challenges with > switchdev offloading of stacked interfaces between the physical port and > the bridge, and recommended to just catch that condition and deny the > CHANGEUPPER event: > https://lore.kernel.org/netdev/20210210105949.GB287766@xxxxxxxxxxxx/ > > But in fact, we might need to deal with the hard thing anyway, which is > to replay all FDB addresses relevant to this port, because it isn't just > static FDB entries, but also local addresses (ones that are not > forwarded but terminated by the bridge). There, we can't just say 'oh > yeah, there was an upper already so I'm not joining that'. > > So, similar to the logic for replaying MDB entries, add a function that > must be called by individual switchdev drivers and replays local FDB > entries as well as ones pointing towards a bridge port. This time, we > use the atomic switchdev notifier block, since that's what FDB entries > expect for some reason. > > Reported-by: Ido Schimmel <idosch@xxxxxxxxxx> > Signed-off-by: Vladimir Oltean <vladimir.oltean@xxxxxxx> > --- > include/linux/if_bridge.h | 9 +++++++ > include/net/switchdev.h | 1 + > net/bridge/br_fdb.c | 52 +++++++++++++++++++++++++++++++++++++++ > net/dsa/dsa_priv.h | 1 + > net/dsa/port.c | 4 +++ > net/dsa/slave.c | 2 +- > 6 files changed, 68 insertions(+), 1 deletion(-) > > diff --git a/include/linux/if_bridge.h b/include/linux/if_bridge.h > index 4c25dafb013d..89596134e88f 100644 > --- a/include/linux/if_bridge.h > +++ b/include/linux/if_bridge.h > @@ -147,6 +147,8 @@ void br_fdb_clear_offload(const struct net_device *dev, u16 vid); > bool br_port_flag_is_set(const struct net_device *dev, unsigned long flag); > u8 br_port_get_stp_state(const struct net_device *dev); > clock_t br_get_ageing_time(struct net_device *br_dev); > +int br_fdb_replay(struct net_device *br_dev, struct net_device *dev, > + struct notifier_block *nb); > #else > static inline struct net_device * > br_fdb_find_port(const struct net_device *br_dev, > @@ -175,6 +177,13 @@ static inline clock_t br_get_ageing_time(struct net_device *br_dev) > { > return 0; > } > + > +static inline int br_fdb_replay(struct net_device *br_dev, > + struct net_device *dev, > + struct notifier_block *nb) > +{ > + return -EINVAL; > +} > #endif > > #endif > diff --git a/include/net/switchdev.h b/include/net/switchdev.h > index b7fc7d0f54e2..7688ec572757 100644 > --- a/include/net/switchdev.h > +++ b/include/net/switchdev.h > @@ -205,6 +205,7 @@ struct switchdev_notifier_info { > > struct switchdev_notifier_fdb_info { > struct switchdev_notifier_info info; /* must be first */ > + struct list_head list; > const unsigned char *addr; > u16 vid; > u8 added_by_user:1, > diff --git a/net/bridge/br_fdb.c b/net/bridge/br_fdb.c > index b7490237f3fc..49125cc196ac 100644 > --- a/net/bridge/br_fdb.c > +++ b/net/bridge/br_fdb.c > @@ -726,6 +726,58 @@ static inline size_t fdb_nlmsg_size(void) > + nla_total_size(sizeof(u8)); /* NFEA_ACTIVITY_NOTIFY */ > } > > +static int br_fdb_replay_one(struct notifier_block *nb, > + struct net_bridge_fdb_entry *fdb, > + struct net_device *dev) > +{ > + struct switchdev_notifier_fdb_info item; > + int err; > + > + item.addr = fdb->key.addr.addr; > + item.vid = fdb->key.vlan_id; > + item.added_by_user = test_bit(BR_FDB_ADDED_BY_USER, &fdb->flags); > + item.offloaded = test_bit(BR_FDB_OFFLOADED, &fdb->flags); > + item.info.dev = dev; > + > + err = nb->notifier_call(nb, SWITCHDEV_FDB_ADD_TO_DEVICE, &item); > + return notifier_to_errno(err); > +} > + > +int br_fdb_replay(struct net_device *br_dev, struct net_device *dev, > + struct notifier_block *nb) > +{ > + struct net_bridge_fdb_entry *fdb; > + struct net_bridge *br; > + int err = 0; > + > + if (!netif_is_bridge_master(br_dev)) > + return -EINVAL; > + > + if (!netif_is_bridge_port(dev)) > + return -EINVAL; > + > + br = netdev_priv(br_dev); > + > + rcu_read_lock(); > + > + hlist_for_each_entry_rcu(fdb, &br->fdb_list, fdb_node) { > + struct net_device *dst_dev; > + > + dst_dev = fdb->dst ? fdb->dst->dev : br->dev; > + if (dst_dev != br_dev && dst_dev != dev) > + continue; > + I do not know if it is a problem or not, more of an observation: This is not guaranteed to be an exact replay of the events that the bridge port (i.e. bond0 or whatever) has received since, in fdb_insert, we exit early when adding local entries if that address is already in the database. Do we have to guard against this somehow? Or maybe we should consider the current behavior a bug and make sure to always send the event in the first place? > + err = br_fdb_replay_one(nb, fdb, dst_dev); > + if (err) > + break; > + } > + > + rcu_read_unlock(); > + > + return err; > +} > +EXPORT_SYMBOL(br_fdb_replay); > + > static void fdb_notify(struct net_bridge *br, > const struct net_bridge_fdb_entry *fdb, int type, > bool swdev_notify) > diff --git a/net/dsa/dsa_priv.h b/net/dsa/dsa_priv.h > index b14c43cb88bb..92282de54230 100644 > --- a/net/dsa/dsa_priv.h > +++ b/net/dsa/dsa_priv.h > @@ -262,6 +262,7 @@ static inline bool dsa_tree_offloads_bridge_port(struct dsa_switch_tree *dst, > > /* slave.c */ > extern const struct dsa_device_ops notag_netdev_ops; > +extern struct notifier_block dsa_slave_switchdev_notifier; > extern struct notifier_block dsa_slave_switchdev_blocking_notifier; > > void dsa_slave_mii_bus_init(struct dsa_switch *ds); > diff --git a/net/dsa/port.c b/net/dsa/port.c > index 6670612f96c6..9850051071f2 100644 > --- a/net/dsa/port.c > +++ b/net/dsa/port.c > @@ -205,6 +205,10 @@ static int dsa_port_switchdev_sync(struct dsa_port *dp, > if (err && err != -EOPNOTSUPP) > return err; > > + err = br_fdb_replay(br, brport_dev, &dsa_slave_switchdev_notifier); > + if (err && err != -EOPNOTSUPP) > + return err; > + > return 0; > } > > diff --git a/net/dsa/slave.c b/net/dsa/slave.c > index b974d8f84a2e..c51e52418a62 100644 > --- a/net/dsa/slave.c > +++ b/net/dsa/slave.c > @@ -2392,7 +2392,7 @@ static struct notifier_block dsa_slave_nb __read_mostly = { > .notifier_call = dsa_slave_netdevice_event, > }; > > -static struct notifier_block dsa_slave_switchdev_notifier = { > +struct notifier_block dsa_slave_switchdev_notifier = { > .notifier_call = dsa_slave_switchdev_event, > }; > > -- > 2.25.1
