On 20.08.21 13:57, Vladimir Oltean wrote:
> Problem statement:
>
> Any time a driver needs to create a private association between a bridge
> upper interface and use that association within its
> SWITCHDEV_FDB_{ADD,DEL}_TO_DEVICE handler, we have an issue with FDB
> entries deleted by the bridge when the port leaves. The issue is that
> all switchdev drivers schedule a work item to have sleepable context,
> and that work item can be actually scheduled after the port has left the
> bridge, which means the association might have already been broken by
> the time the scheduled FDB work item attempts to use it.
>
> The solution is to modify switchdev to use its embedded SWITCHDEV_F_DEFER
> mechanism to make the FDB notifiers emitted from the fastpath be
> scheduled in sleepable context. All drivers are converted to handle
> SWITCHDEV_FDB_{ADD,DEL}_TO_DEVICE from their blocking notifier block
> handler (or register a blocking switchdev notifier handler if they
> didn't have one). This solves the aforementioned problem because the
> bridge waits for the switchdev deferred work items to finish before a
> port leaves (del_nbp calls switchdev_deferred_process), whereas a work
> item privately scheduled by the driver will obviously not be waited upon
> by the bridge, leading to the possibility of having the race.
>
> This is a dependency for the "DSA FDB isolation" posted here. It was
> split out of that series hence the numbering starts directly at v2.
>
> https://patchwork.kernel.org/project/netdevbpf/cover/20210818120150.892647-1-vladimir.oltean@xxxxxxx/
>
> Changes in v3:
> - make "addr" part of switchdev_fdb_notifier_info to avoid dangling
> pointers not watched by RCU
> - mlx5 correction
> - build fixes in the S/390 qeth driver
>
> Vladimir Oltean (7):
> net: bridge: move br_fdb_replay inside br_switchdev.c
> net: switchdev: keep the MAC address by value in struct
> switchdev_notifier_fdb_info
> net: switchdev: move SWITCHDEV_FDB_{ADD,DEL}_TO_DEVICE to the blocking
> notifier chain
> net: bridge: switchdev: make br_fdb_replay offer sleepable context to
> consumers
> net: switchdev: drop the atomic notifier block from
> switchdev_bridge_port_{,un}offload
> net: switchdev: don't assume RCU context in
> switchdev_handle_fdb_{add,del}_to_device
> net: dsa: handle SWITCHDEV_FDB_{ADD,DEL}_TO_DEVICE synchronously
>
> .../ethernet/freescale/dpaa2/dpaa2-switch.c | 75 ++++------
> .../marvell/prestera/prestera_switchdev.c | 104 ++++++-------
> .../mellanox/mlx5/core/en/rep/bridge.c | 65 +++++++--
> .../ethernet/mellanox/mlx5/core/esw/bridge.c | 2 +-
> .../ethernet/mellanox/mlxsw/spectrum_router.c | 4 +-
> .../mellanox/mlxsw/spectrum_switchdev.c | 62 ++++++--
> .../microchip/sparx5/sparx5_mactable.c | 2 +-
> .../microchip/sparx5/sparx5_switchdev.c | 72 ++++-----
> drivers/net/ethernet/mscc/ocelot_net.c | 3 -
> drivers/net/ethernet/rocker/rocker_main.c | 67 ++++-----
> drivers/net/ethernet/rocker/rocker_ofdpa.c | 6 +-
> drivers/net/ethernet/ti/am65-cpsw-nuss.c | 4 +-
> drivers/net/ethernet/ti/am65-cpsw-switchdev.c | 54 +++----
> drivers/net/ethernet/ti/cpsw_new.c | 4 +-
> drivers/net/ethernet/ti/cpsw_switchdev.c | 57 ++++----
> drivers/s390/net/qeth_l2_main.c | 26 ++--
> include/net/switchdev.h | 33 ++++-
> net/bridge/br.c | 5 +-
> net/bridge/br_fdb.c | 54 -------
> net/bridge/br_private.h | 6 -
> net/bridge/br_switchdev.c | 128 +++++++++++++---
> net/dsa/dsa.c | 15 --
> net/dsa/dsa_priv.h | 15 --
> net/dsa/port.c | 3 -
> net/dsa/slave.c | 138 ++++++------------
> net/switchdev/switchdev.c | 61 +++++++-
> 26 files changed, 550 insertions(+), 515 deletions(-)
>
For drivers/s390/net/qeth_l2_main.c :
Reviewed-and-tested-by: Alexandra Winter <wintera@xxxxxxxxxxxxx>
Thank you for this proposal, it makes qeth switchdev code more robust, cleaner and gives the
opportunity for future enhancements, like you proposed.
