From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=from:to:cc:subject:in-reply-to:references:date:message-id :mime-version; bh=GUNacRM0Kzot4Ci3+9/rQiAP6HGdFO8cNfIKSh2/JpE=; b=Jdm0puZZ/Q6dFz353KCoDZvifEBG6tzHxW6igmTgxd+obwpPQAudDXwNknS/hhz/dn qCVif8Hnrp91CoRN93+vhhSXQr3O0aViX2rpkgbxco2CgKXm4vcj3xV/rB7waIx9ztsB R0mmMVc818zGQV6acVGBsI2XRGtQi23j0NZdJQ3tP5uOe3ghbIsHipM4baigfeZK+Sfz 9sAsxvFUgiFl3NTSys9UjwoH0U+wR2PDNR7Z1KBKZCVkk4oU810jgtSTRDxyYTPoLCQd Dlvwu7iShS+Uf6N70yehFjkjjuL8gZFZjRNybtYbtHRcPvurxM4JhK/VMh4Hvuhcn2/e dgZA== From: Hans Schultz In-Reply-To: <20220323112116.q6shx2g4r23ungtc@skbuf> References: <20220317172013.rhjvknre5w7mfmlo@skbuf> <86tubvk24r.fsf@gmail.com> <20220318121400.sdc4guu5m4auwoej@skbuf> <86pmmjieyl.fsf@gmail.com> <20220318131943.hc7z52beztqlzwfq@skbuf> <86a6dixnd2.fsf@gmail.com> <20220322110806.kbdb362jf6pbtqaf@skbuf> <86fsn90ye8.fsf@gmail.com> <20220323101643.kum3nuqctunakcfo@skbuf> <864k3p5437.fsf@gmail.com> <20220323112116.q6shx2g4r23ungtc@skbuf> Date: Wed, 23 Mar 2022 12:43:03 +0100 Message-ID: <86tuboao8o.fsf@gmail.com> MIME-Version: 1.0 Content-Type: text/plain Subject: Re: [Bridge] [PATCH net-next 3/3] net: dsa: mv88e6xxx: mac-auth/MAB implementation List-Id: Linux Ethernet Bridging List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Vladimir Oltean , Hans Schultz Cc: Ivan Vecera , Andrew Lunn , Florian Fainelli , Jiri Pirko , Daniel Borkmann , netdev@vger.kernel.org, Nikolay Aleksandrov , bridge@lists.linux-foundation.org, linux-kernel@vger.kernel.org, Vivien Didelot , Ido Schimmel , Roopa Prabhu , kuba@kernel.org, davem@davemloft.net On ons, mar 23, 2022 at 13:21, Vladimir Oltean 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);