lkml.org 
[lkml]   [2022]   [Mar]   [23]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
SubjectRe: [PATCH net-next 3/3] net: dsa: mv88e6xxx: mac-auth/MAB implementation
Date
On ons, mar 23, 2022 at 13:21, Vladimir Oltean <olteanv@gmail.com> wrote:
> On Wed, Mar 23, 2022 at 11:57:16AM +0100, Hans Schultz wrote:
>> >> >> 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.

So something like?
mv88e6xxx_reg_unlock(chip);
rtnl_lock();
err = call_switchdev_notifiers(SWITCHDEV_FDB_ADD_TO_BRIDGE, brport, &info.info, NULL);
rtnl_unlock();
mv88e6xxx_reg_lock(chip);

\
 
 \ /
  Last update: 2022-03-23 12:44    [W:0.159 / U:1.932 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site