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  1. 24 Mar, 2021 30 commits
  3. 23 Mar, 2021 10 commits
    • David S. Miller's avatar
      Merge branch 'bridge-dsa-sandwiched-LAG' · c692a0be
      David S. Miller authored 
      Vladimir Oltean says:

====================
Better support for sandwiched LAGs with bridge and DSA

Changes in v4:
- Added missing EXPORT_SYMBOL_GPL
- Using READ_ONCE(fdb->dst)
- Split patches into (a) adding the bridge helpers (b) making DSA use them
- br_mdb_replay went back to the v1 approach where it allocated memory
  in atomic context
- Created a br_switchdev_mdb_populate which reduces some of the code
  duplication
- Fixed the error message in dsa_port_clear_brport_flags
- Replaced "dsa_port_vlan_filtering(dp, br, extack)" with
  "dsa_port_vlan_filtering(dp, br_vlan_enabled(br), extack)" (duh)
- Added review tags (sorry if I missed any)

The objective of this series is to make LAG uppers on top of switchdev
ports work regardless of which order we link interfaces to their masters
(first make the port join the LAG, then the LAG join the bridge, or the
other way around).

There was a design decision to be made in patches 2-4 on whether we
should adopt the "push" model (which attempts to solve the problem
centrally, in the bridge layer) where the driver just calls:

  switchdev_bridge_port_offloaded(brport_dev,
                                  &atomic_notifier_block,
                                  &blocking_notifier_block,
                                  extack);

and the bridge just replays the entire collection of switchdev port
attributes and objects that it has, in some predefined order and with
some predefined error handling logic;

or the "pull" model (which attempts to solve the problem by giving the
driver the rope to hang itself), where the driver, apart from calling:

  switchdev_bridge_port_offloaded(brport_dev, extack);

has the task of "dumpster diving" (as Tobias puts it) through the bridge
attributes and objects by itself, by calling:

  - br_vlan_replay
  - br_fdb_replay
  - br_mdb_replay
  - br_vlan_enabled
  - br_port_flag_is_set
  - br_port_get_stp_state
  - br_multicast_router
  - br_get_ageing_time

(not necessarily all of them, and not necessarily in this order, and
with driver-defined error handling).

Even though I'm not in love myself with the "pull" model, I chose it
because there is a fundamental trick with replaying switchdev events
like this:

ip link add br0 type bridge
ip link add bond0 type bond
ip link set bond0 master br0
ip link set swp0 master bond0 <- this will replay the objects once for
                                 the bond0 bridge port, and the swp0
                                 switchdev port will process them
ip link set swp1 master bond0 <- this will replay the objects again for
                                 the bond0 bridge port, and the swp1
                                 switchdev port will see them, but swp0
                                 will see them for the second time now

Basically I believe that it is implementation defined whether the driver
wants to error out on switchdev objects seen twice on a port, and the
bridge should not enforce a certain model for that. For example, for FDB
entries added to a bonding interface, the underling switchdev driver
might have an abstraction for just that: an FDB entry pointing towards a
logical (as opposed to physical) port. So when the second port joins the
bridge, it doesn't realy need to replay FDB entries, since there is
already at least one hardware port which has been receiving those
events, and the FDB entries don't need to be added a second time to the
same logical port.
In the other corner, we have the drivers that handle switchdev port
attributes on a LAG as individual switchdev port attributes on physical
ports (example: VLAN filtering). In fact, the switchdev_handle_port_attr_set
helper facilitates this: it is a fan-out from a single orig_dev towards
multiple lowers that pass the check_cb().
But that's the point: switchdev_handle_port_attr_set is just a helper
which the driver _opts_ to use. The bridge can't enforce the "push"
model, because that would assume that all drivers handle port attributes
in the same way, which is probably false.

For this reason, I preferred to go with the "pull" mode for this patch
set. Just to see how bad it is for other switchdev drivers to copy-paste
this logic, I added the pull support to ocelot too, and I think it's
pretty manageable.
====================
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      c692a0be
    • Vladimir Oltean's avatar
      net: ocelot: replay switchdev events when joining bridge · e4bd44e8
      Vladimir Oltean authored 
      The premise of this change is that the switchdev port attributes and
objects offloaded by ocelot might have been missed when we are joining
an already existing bridge port, such as a bonding interface.

The patch pulls these switchdev attributes and objects from the bridge,
on behalf of the 'bridge port' net device which might be either the
ocelot switch interface, or the bonding upper interface.

The ocelot_net.c belongs strictly to the switchdev ocelot driver, while
ocelot.c is part of a library shared with the DSA felix driver.
The ocelot_port_bridge_leave function (part of the common library) used
to call ocelot_port_vlan_filtering(false), something which is not
necessary for DSA, since the framework deals with that already there.
So we move this function to ocelot_switchdev_unsync, which is specific
to the switchdev driver.

The code movement described above makes ocelot_port_bridge_leave no
longer return an error code, so we change its type from int to void.
Signed-off-by: default avatarVladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      e4bd44e8
    • Vladimir Oltean's avatar
      net: ocelot: call ocelot_netdevice_bridge_join when joining a bridged LAG · 81ef35e7
      Vladimir Oltean authored 
      Similar to the DSA situation, ocelot supports LAG offload but treats
this scenario improperly:

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

We do the same thing as we do there, which is to simulate a 'bridge join'
on 'lag join', if we detect that the bonding upper has a bridge upper.

Again, same as DSA, ocelot supports software fallback for LAG, and in
that case, we should avoid calling ocelot_netdevice_changeupper.
Signed-off-by: default avatarVladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      81ef35e7
    • Vladimir Oltean's avatar
      net: dsa: sync up switchdev objects and port attributes when joining the bridge · 010e269f
      Vladimir Oltean authored 
      If we join an already-created bridge port, such as a bond master
interface, then we can miss the initial switchdev notifications emitted
by the bridge for this port, while it wasn't offloaded by anybody.
Signed-off-by: default avatarVladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      010e269f
    • Vladimir Oltean's avatar
      net: dsa: inherit the actual bridge port flags at join time · 5961d6a1
      Vladimir Oltean authored 
      DSA currently assumes that the bridge port starts off with this
constellation of bridge port flags:

- learning on
- unicast flooding on
- multicast flooding on
- broadcast flooding on

just by virtue of code copy-pasta from the bridge layer (new_nbp).
This was a simple enough strategy thus far, because the 'bridge join'
moment always coincided with the 'bridge port creation' moment.

But with sandwiched interfaces, such as:

 br0
  |
bond0
  |
 swp0

it may happen that the user has had time to change the bridge port flags
of bond0 before enslaving swp0 to it. In that case, swp0 will falsely
assume that the bridge port flags are those determined by new_nbp, when
in fact this can happen:

ip link add br0 type bridge
ip link add bond0 type bond
ip link set bond0 master br0
ip link set bond0 type bridge_slave learning off
ip link set swp0 master br0

Now swp0 has learning enabled, bond0 has learning disabled. Not nice.

Fix this by "dumpster diving" through the actual bridge port flags with
br_port_flag_is_set, at bridge join time.

We use this opportunity to split dsa_port_change_brport_flags into two
distinct functions called dsa_port_inherit_brport_flags and
dsa_port_clear_brport_flags, now that the implementation for the two
cases is no longer similar. This patch also creates two functions called
dsa_port_switchdev_sync and dsa_port_switchdev_unsync which collect what
we have so far, even if that's asymmetrical. More is going to be added
in the next patch.
Signed-off-by: default avatarVladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      5961d6a1
    • Vladimir Oltean's avatar
      net: dsa: pass extack to dsa_port_{bridge,lag}_join · 2afc526a
      Vladimir Oltean authored 
      This is a pretty noisy change that was broken out of the larger change
for replaying switchdev attributes and objects at bridge join time,
which is when these extack objects are actually used.
Signed-off-by: default avatarVladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: default avatarFlorian Fainelli <f.fainelli@gmail.com>
Reviewed-by: default avatarTobias Waldekranz <tobias@waldekranz.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      2afc526a
    • Vladimir Oltean's avatar
      net: dsa: call dsa_port_bridge_join when joining a LAG that is already in a bridge · 185c9a76
      Vladimir Oltean authored 
      DSA can properly detect and offload this sequence of operations:

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

But not this one:

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

Actually the second one is more complicated, due to the elapsed time
between the enslavement of bond0 and the offloading of it via swp0, a
lot of things could have happened to the bond0 bridge port in terms of
switchdev objects (host MDBs, VLANs, altered STP state etc). So this is
a bit of a can of worms, and making sure that the DSA port's state is in
sync with this already existing bridge port is handled in the next
patches.
Signed-off-by: default avatarVladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: default avatarFlorian Fainelli <f.fainelli@gmail.com>
Reviewed-by: default avatarTobias Waldekranz <tobias@waldekranz.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      185c9a76
    • Vladimir Oltean's avatar
      net: bridge: add helper to replay VLANs installed on port · 22f67cdf
      Vladimir Oltean authored 
      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: default avatarVladimir Oltean <vladimir.oltean@nxp.com>
Acked-by: default avatarNikolay Aleksandrov <nikolay@nvidia.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      22f67cdf
    • Vladimir Oltean's avatar
      net: bridge: add helper to replay port and local fdb entries · 04846f90
      Vladimir Oltean authored 
      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: default avatarIdo Schimmel <idosch@idosch.org>
Signed-off-by: default avatarVladimir Oltean <vladimir.oltean@nxp.com>
Acked-by: default avatarNikolay Aleksandrov <nikolay@nvidia.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      04846f90
    • Vladimir Oltean's avatar
      net: bridge: add helper to replay port and host-joined mdb entries · 4f2673b3
      Vladimir Oltean authored 
      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: default avatarIdo Schimmel <idosch@idosch.org>
Signed-off-by: default avatarVladimir Oltean <vladimir.oltean@nxp.com>
Acked-by: default avatarNikolay Aleksandrov <nikolay@nvidia.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      4f2673b3
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