linux-toradex.git/include/linux/if_bridge.h, branch v5.14-rc6

net: bridge: allow the switchdev replay functions to be called for deletion

2021-06-28T21:09:03+00:00

When a switchdev port leaves a LAG that is a bridge port, the switchdev
objects and port attributes offloaded to that port are not removed:

ip link add br0 type bridge
ip link add bond0 type bond mode 802.3ad
ip link set swp0 master bond0
ip link set bond0 master br0
bridge vlan add dev bond0 vid 100
ip link set swp0 nomaster

VLAN 100 will remain installed on swp0 despite it going into standalone
mode, because as far as the bridge is concerned, nothing ever happened
to its bridge port.

Let's extend the bridge vlan, fdb and mdb replay functions to take a
'bool adding' argument, and make DSA and ocelot call the replay
functions with 'adding' as false from the switchdev unsync path, for the
switch port that leaves the bridge.

Note that this patch in itself does not salvage anything, because in the
current pull mode of operation, DSA still needs to call the replay
helpers with adding=false. This will be done in another patch.

Signed-off-by: Vladimir Oltean 
Reviewed-by: Florian Fainelli 
Signed-off-by: David S. Miller

net: bridge: constify variables in the replay helpers

2021-06-28T21:09:03+00:00

Some of the arguments and local variables for the newly added switchdev
replay helpers can be const, so let's make them so.

Signed-off-by: Vladimir Oltean 
Reviewed-by: Florian Fainelli 
Signed-off-by: David S. Miller

net: bridge: ignore switchdev events for LAG ports which didn't request replay

2021-06-28T21:09:03+00:00

There is a slight inconvenience in the switchdev replay helpers added
recently, and this is when:

ip link add br0 type bridge
ip link add bond0 type bond
ip link set bond0 master br0
bridge vlan add dev bond0 vid 100
ip link set swp0 master bond0
ip link set swp1 master bond0

Since the underlying driver (currently only DSA) asks for a replay of
VLANs when swp0 and swp1 join the LAG because it is bridged, what will
happen is that DSA will try to react twice on the VLAN event for swp0.
This is not really a huge problem right now, because most drivers accept
duplicates since the bridge itself does, but it will become a problem
when we add support for replaying switchdev object deletions.

Let's fix this by adding a blank void *ctx in the replay helpers, which
will be passed on by the bridge in the switchdev notifications. If the
context is NULL, everything is the same as before. But if the context is
populated with a valid pointer, the underlying switchdev driver
(currently DSA) can use the pointer to 'see through' the bridge port
(which in the example above is bond0) and 'know' that the event is only
for a particular physical port offloading that bridge port, and not for
all of them.

Signed-off-by: Vladimir Oltean 
Reviewed-by: Florian Fainelli 
Signed-off-by: David S. Miller

net: bridge: mcast: export multicast router presence adjacent to a port

2021-05-13T21:04:31+00:00

To properly support routable multicast addresses in batman-adv in a
group-aware way, a batman-adv node needs to know if it serves multicast
routers.

This adds a function to the bridge to export this so that batman-adv
can then make full use of the Multicast Router Discovery capability of
the bridge.

Signed-off-by: Linus Lüssing 
Signed-off-by: David S. Miller

net: bridge: add helper to replay VLANs installed on port

2021-03-23T21:49:05+00:00

Currently this simple setup with DSA:

ip link add br0 type bridge vlan_filtering 1
ip link add bond0 type bond
ip link set bond0 master br0
ip link set swp0 master bond0

will not work because the bridge has created the PVID in br_add_if ->
nbp_vlan_init, and it has notified switchdev of the existence of VLAN 1,
but that was too early, since swp0 was not yet a lower of bond0, so it
had no reason to act upon that notification.

We need a helper in the bridge to replay the switchdev VLAN objects that
were notified since the bridge port creation, because some of them may
have been missed.

As opposed to the br_mdb_replay function, the vg->vlan_list write side
protection is offered by the rtnl_mutex which is sleepable, so we don't
need to queue up the objects in atomic context, we can replay them right
away.

Signed-off-by: Vladimir Oltean 
Acked-by: Nikolay Aleksandrov 
Signed-off-by: David S. Miller

net: bridge: add helper to replay port and local fdb entries

2021-03-23T21:49:05+00:00

When a switchdev port starts offloading a LAG that is already in a
bridge and has 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 switchdev driver 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@shredder.lan/

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 
Signed-off-by: Vladimir Oltean 
Acked-by: Nikolay Aleksandrov 
Signed-off-by: David S. Miller

net: bridge: add helper to replay port and host-joined mdb entries

2021-03-23T21:49:05+00:00

I have a system with DSA ports, and udhcpcd is configured to bring
interfaces up as soon as they are created.

I create a bridge as follows:

ip link add br0 type bridge

As soon as I create the bridge and udhcpcd brings it up, I also have
avahi which automatically starts sending IPv6 packets to advertise some
local services, and because of that, the br0 bridge joins the following
IPv6 groups due to the code path detailed below:

33:33:ff:6d:c1:9c vid 0
33:33:00:00:00:6a vid 0
33:33:00:00:00:fb vid 0

br_dev_xmit
-> br_multicast_rcv
   -> br_ip6_multicast_add_group
      -> __br_multicast_add_group
         -> br_multicast_host_join
            -> br_mdb_notify

This is all fine, but inside br_mdb_notify we have br_mdb_switchdev_host
hooked up, and switchdev will attempt to offload the host joined groups
to an empty list of ports. Of course nobody offloads them.

Then when we add a port to br0:

ip link set swp0 master br0

the bridge doesn't replay the host-joined MDB entries from br_add_if,
and eventually the host joined addresses expire, and a switchdev
notification for deleting it is emitted, but surprise, the original
addition was already completely missed.

The strategy to address this problem is to replay the MDB entries (both
the port ones and the host joined ones) when the new port joins the
bridge, similar to what vxlan_fdb_replay does (in that case, its FDB can
be populated and only then attached to a bridge that you offload).
However there are 2 possibilities: the addresses can be 'pushed' by the
bridge into the port, or the port can 'pull' them from the bridge.

Considering that in the general case, the new port can be really late to
the party, and there may have been many other switchdev ports that
already received the initial notification, we would like to avoid
delivering duplicate events to them, since they might misbehave. And
currently, the bridge calls the entire switchdev notifier chain, whereas
for replaying it should just call the notifier block of the new guy.
But the bridge doesn't know what is the new guy's notifier block, it
just knows where the switchdev notifier chain is. So for simplification,
we make this a driver-initiated pull for now, and the notifier block is
passed as an argument.

To emulate the calling context for mdb objects (deferred and put on the
blocking notifier chain), we must iterate under RCU protection through
the bridge's mdb entries, queue them, and only call them once we're out
of the RCU read-side critical section.

There was some opportunity for reuse between br_mdb_switchdev_host_port,
br_mdb_notify and the newly added br_mdb_queue_one in how the switchdev
mdb object is created, so a helper was created.

Suggested-by: Ido Schimmel 
Signed-off-by: Vladimir Oltean 
Acked-by: Nikolay Aleksandrov 
Signed-off-by: David S. Miller

net: bridge: add helper to retrieve the current ageing time

2021-03-23T21:49:05+00:00

The SWITCHDEV_ATTR_ID_BRIDGE_AGEING_TIME attribute is only emitted from:

sysfs/ioctl/netlink
-> br_set_ageing_time
   -> __set_ageing_time

therefore not at bridge port creation time, so:
(a) switchdev drivers have to hardcode the initial value for the address
    ageing time, because they didn't get any notification
(b) that hardcoded value can be out of sync, if the user changes the
    ageing time before enslaving the port to the bridge

We need a helper in the bridge, such that switchdev drivers can query
the current value of the bridge ageing time when they start offloading
it.

Signed-off-by: Vladimir Oltean 
Reviewed-by: Florian Fainelli 
Reviewed-by: Tobias Waldekranz 
Acked-by: Nikolay Aleksandrov 
Signed-off-by: David S. Miller

net: bridge: add helper for retrieving the current bridge port STP state

2021-03-23T21:49:05+00:00

It may happen that we have the following topology with DSA or any other
switchdev driver with LAG offload:

ip link add br0 type bridge stp_state 1
ip link add bond0 type bond
ip link set bond0 master br0
ip link set swp0 master bond0
ip link set swp1 master bond0

STP decides that it should put bond0 into the BLOCKING state, and
that's that. The ports that are actively listening for the switchdev
port attributes emitted for the bond0 bridge port (because they are
offloading it) and have the honor of seeing that switchdev port
attribute can react to it, so we can program swp0 and swp1 into the
BLOCKING state.

But if then we do:

ip link set swp2 master bond0

then as far as the bridge is concerned, nothing has changed: it still
has one bridge port. But this new bridge port will not see any STP state
change notification and will remain FORWARDING, which is how the
standalone code leaves it in.

We need a function in the bridge driver which retrieves the current STP
state, such that drivers can synchronize to it when they may have missed
switchdev events.

Signed-off-by: Vladimir Oltean 
Reviewed-by: Florian Fainelli 
Reviewed-by: Tobias Waldekranz 
Acked-by: Nikolay Aleksandrov 
Signed-off-by: David S. Miller

net: bridge: mcast: add support for raw L2 multicast groups

2020-10-31T00:49:19+00:00

Extend the bridge multicast control and data path to configure routes
for L2 (non-IP) multicast groups.

The uapi struct br_mdb_entry union u is extended with another variant,
mac_addr, which does not change the structure size, and which is valid
when the proto field is zero.

To be compatible with the forwarding code that is already in place,
which acts as an IGMP/MLD snooping bridge with querier capabilities, we
need to declare that for L2 MDB entries (for which there exists no such
thing as IGMP/MLD snooping/querying), that there is always a querier.
Otherwise, these entries would be flooded to all bridge ports and not
just to those that are members of the L2 multicast group.

Needless to say, only permanent L2 multicast groups can be installed on
a bridge port.

Signed-off-by: Nikolay Aleksandrov 
Signed-off-by: Vladimir Oltean 
Link: https://lore.kernel.org/r/20201028233831.610076-1-vladimir.oltean@nxp.com
Signed-off-by: Jakub Kicinski