From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752103AbcGRUkN (ORCPT ); Mon, 18 Jul 2016 16:40:13 -0400 Received: from mail.savoirfairelinux.com ([208.88.110.44]:56698 "EHLO mail.savoirfairelinux.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751211AbcGRUkJ (ORCPT ); Mon, 18 Jul 2016 16:40:09 -0400 From: Vivien Didelot To: Andrew Lunn Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, kernel@savoirfairelinux.com, "David S. Miller" , Florian Fainelli Subject: Re: [PATCH v2 net-next v2 12/12] net: dsa: mv88e6xxx: add support for DSA ageing time In-Reply-To: <20160718201334.GS31103@lunn.ch> References: <20160718184628.13103-1-vivien.didelot@savoirfairelinux.com> <20160718184628.13103-13-vivien.didelot@savoirfairelinux.com> <20160718191644.GG31103@lunn.ch> <87d1malpcd.fsf@ketchup.mtl.sfl> <20160718193253.GJ31103@lunn.ch> <87eg6q3efp.fsf@ketchup.mtl.sfl> <20160718201334.GS31103@lunn.ch> User-Agent: Notmuch/0.22 (http://notmuchmail.org) Emacs/24.5.1 (x86_64-unknown-linux-gnu) Date: Mon, 18 Jul 2016 16:40:03 -0400 Message-ID: <87k2gibrz0.fsf@ketchup.mtl.sfl> MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Andrew, Andrew Lunn writes: > On Mon, Jul 18, 2016 at 03:59:38PM -0400, Vivien Didelot wrote: >> Andrew Lunn writes: >> >> >> Nope, the bridge ageing time is not per-port, even though switchdev ops >> >> are per-port by design. This is a switch-wide attribute. >> > >> > So you are saying the core is doing all the reference counting, etc, >> > when swapping between fast and slow ageing? >> >> I don't see how checking for the fastest ageing time would fix support >> for multiple bridges... > > The bridge should switch to fast ageing after a topology change to > flush out entries which are now wrong. Using the short age time for > too long results in a bit more inefficiency, in that entries time out > faster than they need to. But if we go back to slow ageing too > quickly, e.g. because of another bridge, we get wrong operation, in > that bad entries can get stuck in the table for up to 5 minutes. > > So either we need to keep fast ageing as long as there is one bridge > fast ageing, or we need to flush the whole MAC cache for a bridge on > topology change and don't bother with fast ageing at all. > >> Maybe we can keep it simple for the moment with this switch-wide >> set_ageing_time operation, and later add a patch for the DSA layer to >> cache and elect the ageing time per-port or per-bridge. > > I don't think it can be done at the DSA layer. It does not have the > information needed. OK. I think caching per-port (and thus per-bridge) ageing time would do the trick and keep DSA drivers simple. What about the following patch? diff --git a/include/net/dsa.h b/include/net/dsa.h index 238fad9..2217a3f 100644 --- a/include/net/dsa.h +++ b/include/net/dsa.h @@ -141,6 +141,7 @@ struct dsa_switch_tree { struct dsa_port { struct net_device *netdev; struct device_node *dn; + unsigned int ageing_time; }; struct dsa_switch { diff --git a/net/dsa/slave.c b/net/dsa/slave.c index 1074cb6..fc91967 100644 --- a/net/dsa/slave.c +++ b/net/dsa/slave.c @@ -333,6 +333,21 @@ static int dsa_slave_vlan_filtering(struct net_device *dev, return 0; } +static int dsa_fastest_ageing_time(struct dsa_switch *ds, + unsigned int ageing_time) +{ + int i; + + for (i = 0; i < DSA_MAX_PORTS; ++i) { + struct dsa_port *dp = &ds->ports[i]; + + if (dp && dp->ageing_time && dp->ageing_time < ageing_time) + ageing_time = dp->ageing_time; + } + + return ageing_time; +} + static int dsa_slave_ageing_time(struct net_device *dev, const struct switchdev_attr *attr, struct switchdev_trans *trans) @@ -346,6 +361,10 @@ static int dsa_slave_ageing_time(struct net_device *dev, if (switchdev_trans_ph_prepare(trans)) return 0; + /* Keep the fastest ageing time in case of multiple bridges */ + ds->ports[p->port].ageing_time = ageing_time; + ageing_time = dsa_fastest_ageing_time(ds, ageing_time); + if (ds->drv->set_ageing_time) return ds->drv->set_ageing_time(ds, ageing_time); Thanks, Vivien