On 30/04/2020 23:25, Vladimir Oltean wrote:

From: Vladimir Oltean <vladimir.oltean@nxp.com>

Commit 8db0a2ee2c63 ("net: bridge: reject DSA-enabled master netdevices
as bridge members") added a special check in br_if.c in order to check
for a DSA master network device with a tagging protocol configured. This
was done because back then, such devices, once enslaved in a bridge
would become inoperative and would not pass DSA tagged traffic anymore
due to br_handle_frame returning RX_HANDLER_CONSUMED.

But right now we have valid use cases which do require bridging of DSA
masters. One such example is when the DSA master ports are DSA switch
ports themselves (in a disjoint tree setup). This should be completely
equivalent, functionally speaking, from having multiple DSA switches
hanging off of the ports of a switchdev driver. So we should allow the
enslaving of DSA tagged master network devices.

Instead of the regular br_handle_frame(), install a new function
br_handle_frame_dummy() on these DSA masters, which returns
RX_HANDLER_PASS in order to call into the DSA specific tagging protocol
handlers, and lift the restriction from br_add_if.

Suggested-by: Nikolay Aleksandrov <redacted>
Suggested-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
---
Changes in v2:
* Removed the hotpath netdev_uses_dsa check and installed a dummy
  rx_handler for such net devices.
* Improved the check of which DSA master net devices are able to be
  bridged and which aren't.
* At this stage, the patch is different enough from where I took it from
  (aka https://github.com/ffainelli/linux/commit/75618cea75ada8d9eef7936c002b5ec3dd3e4eac)
  that I just added my authorship to it).

 include/net/dsa.h       |  2 +-
 net/bridge/br_if.c      | 32 +++++++++++++++++++++++---------
 net/bridge/br_input.c   | 23 ++++++++++++++++++++++-
 net/bridge/br_private.h |  6 +++---
 4 files changed, 49 insertions(+), 14 deletions(-)

Looks good to me, thanks.
Acked-by: Nikolay Aleksandrov <redacted>