On Wed, Mar 23, 2022 at 11:57:16AM +0100, Hans Schultz wrote:

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Another issue I see, is that there is a deadlock or similar issue when
receiving violations and running 'bridge fdb show' (it seemed that
member violations also caused this, but not sure yet...), as the unit
freezes, not to return...

Have you enabled lockdep, debug atomic sleep, detect hung tasks, things
like that?

I have now determined that it is the rtnl_lock() that causes the
"deadlock". The doit() in rtnetlink.c is under rtnl_lock() and is what
takes care of getting the fdb entries when running 'bridge fdb show'. In
principle there should be no problem with this, but I don't know if some
interrupt queue is getting jammed as they are blocked from rtnetlink.c?

Sorry, I forgot to respond yesterday to this.
By any chance do you maybe have an AB/BA lock inversion, where from the
ATU interrupt handler you do mv88e6xxx_reg_lock() -> rtnl_lock(), while
from the port_fdb_dump() handler you do rtnl_lock() -> mv88e6xxx_reg_lock()?

If I release the mv88e6xxx_reg_lock() before calling the handler, I need
to get it again for the mv88e6xxx_g1_atu_loadpurge() call at least. But
maybe the vtu_walk also needs the mv88e6xxx_reg_lock()?
I could also just release the mv88e6xxx_reg_lock() before the
call_switchdev_notifiers() call and reacquire it immediately after?

The cleanest way to go about this would be to have the call_switchdev_notifiers()
portion of the ATU interrupt handling at the very end of mv88e6xxx_g1_atu_prob_irq_thread_fn(),
with no hardware access needed, and therefore no reg_lock() held.