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Date: Wed, 23 Mar 2022 11:46:53 +0100 From: Hans Schultz <schultz.hans@...il.com> To: Vladimir Oltean <olteanv@...il.com>, Hans Schultz <schultz.hans@...il.com> Cc: Andrew Lunn <andrew@...n.ch>, davem@...emloft.net, kuba@...nel.org, netdev@...r.kernel.org, Vivien Didelot <vivien.didelot@...il.com>, Florian Fainelli <f.fainelli@...il.com>, Jiri Pirko <jiri@...nulli.us>, Ivan Vecera <ivecera@...hat.com>, Roopa Prabhu <roopa@...dia.com>, Nikolay Aleksandrov <razor@...ckwall.org>, Daniel Borkmann <daniel@...earbox.net>, Ido Schimmel <idosch@...dia.com>, linux-kernel@...r.kernel.org, bridge@...ts.linux-foundation.org Subject: Re: [PATCH net-next 3/3] net: dsa: mv88e6xxx: mac-auth/MAB implementation On ons, mar 23, 2022 at 12:16, Vladimir Oltean <olteanv@...il.com> wrote: > On Wed, Mar 23, 2022 at 11:13:51AM +0100, Hans Schultz wrote: >> On tis, mar 22, 2022 at 13:08, Vladimir Oltean <olteanv@...il.com> wrote: >> > On Tue, Mar 22, 2022 at 12:01:13PM +0100, Hans Schultz wrote: >> >> On fre, mar 18, 2022 at 15:19, Vladimir Oltean <olteanv@...il.com> wrote: >> >> > On Fri, Mar 18, 2022 at 02:10:26PM +0100, Hans Schultz wrote: >> >> >> In the offloaded case there is no difference between static and dynamic >> >> >> flags, which I see as a general issue. (The resulting ATU entry is static >> >> >> in either case.) >> >> > >> >> > It _is_ a problem. We had the same problem with the is_local bit. >> >> > Independently of this series, you can add the dynamic bit to struct >> >> > switchdev_notifier_fdb_info and make drivers reject it. >> >> > >> >> >> These FDB entries are removed when link goes down (soft or hard). The >> >> >> zero DPV entries that the new code introduces age out after 5 minutes, >> >> >> while the locked flagged FDB entries are removed by link down (thus the >> >> >> FDB and the ATU are not in sync in this case). >> >> > >> >> > Ok, so don't let them disappear from hardware, refresh them from the >> >> > driver, since user space and the bridge driver expect that they are >> >> > still there. >> >> >> >> I have now tested with two extra unmanaged switches (each connected to a >> >> seperate port on our managed switch, and when migrating from one port to >> >> another, there is member violations, but as the initial entry ages out, >> >> a new miss violation occurs and the new port adds the locked entry. In >> >> this case I only see one locked entry, either on the initial port or >> >> later on the port the host migrated to (via switch). >> >> >> >> If I refresh the ATU entries indefinitly, then this migration will for >> >> sure not work, and with the member violation suppressed, it will be >> >> silent about it. >> > >> > Manual says that migrations should trigger miss violations if configured >> > adequately, is this not the case? >> > >> >> So I don't think it is a good idea to refresh the ATU entries >> >> indefinitely. >> >> >> >> 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()? Yes, I forgot that the whole handler is under mv88e6xxx_reg_lock(). I hope then that I can release the mv88e6xxx_reg_lock() before calling the handler function with issues?
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