[PATCH 0/2] net: dsa: RCU-protect dsa_ptr in struct net_device

[A. Sverdlin]

From: Alexander Sverdlin <alexander.sverdlin at siemens.com>

There are multiple races of zeroing dsa_ptr in struct net_device (on
shutdown/remove) against asynchronous dereferences all over the net
code. Widespread pattern is as follows:

CPU0					CPU1
if (netdev_uses_dsa())
					dev->dsa_ptr = NULL;
        dev->dsa_ptr->...

RCU-protect the dsa_ptr and ajust the documentation where unsafe patterns
were mentioned.

The first patch has been compiled with ARCH=arm64 and allyesconfig against
v6.11-rc6. Backported to v6.1 and tested on arm64 HW with LAN9303 switch
(where the issue was initially reproduced), including LOCKDEP and
PROVE_RCU. Therefore I will be able to provide v6.1 backport (for -stable
purposes) and later v6.8 backport as well.

Alexander Sverdlin (2):
  net: dsa: RCU-protect dsa_ptr in struct net_device
  docs: net: dsa: RCU protection of dsa_ptr in struct net_device

 Documentation/networking/dsa/dsa.rst        |  18 ++--
 drivers/net/dsa/mt7530.c                    |   3 +-
 drivers/net/dsa/ocelot/felix.c              |   3 +-
 drivers/net/dsa/qca/qca8k-8xxx.c            |   3 +-
 drivers/net/ethernet/broadcom/bcmsysport.c  |   8 +-
 drivers/net/ethernet/mediatek/airoha_eth.c  |   2 +-
 drivers/net/ethernet/mediatek/mtk_eth_soc.c |  22 +++--
 drivers/net/ethernet/mediatek/mtk_ppe.c     |  15 ++-
 include/linux/netdevice.h                   |   2 +-
 include/net/dsa.h                           |  36 +++++--
 include/net/dsa_stubs.h                     |   6 +-
 net/bridge/br_input.c                       |   2 +-
 net/core/dev.c                              |   3 +-
 net/core/flow_dissector.c                   |  19 ++--
 net/dsa/conduit.c                           |  66 ++++++++-----
 net/dsa/dsa.c                               |  19 ++--
 net/dsa/port.c                              |   3 +-
 net/dsa/tag.c                               |   3 +-
 net/dsa/tag.h                               |  19 ++--
 net/dsa/tag_8021q.c                         |  10 +-
 net/dsa/tag_brcm.c                          |   2 +-
 net/dsa/tag_dsa.c                           |   8 +-
 net/dsa/tag_qca.c                           |  10 +-
 net/dsa/tag_sja1105.c                       |  22 +++--
 net/dsa/user.c                              | 104 +++++++++++---------
 net/ethernet/eth.c                          |   2 +-
 26 files changed, 249 insertions(+), 161 deletions(-)

-- 
2.46.0