From: Vladimir Oltean <olteanv@gmail.com>
To: Tobias Waldekranz <tobias@waldekranz.com>
Cc: davem@davemloft.net, kuba@kernel.org,
Andrew Lunn <andrew@lunn.ch>,
Vivien Didelot <vivien.didelot@gmail.com>,
Florian Fainelli <f.fainelli@gmail.com>,
Jiri Pirko <jiri@resnulli.us>, Ivan Vecera <ivecera@redhat.com>,
Roopa Prabhu <roopa@nvidia.com>,
Nikolay Aleksandrov <razor@blackwall.org>,
Russell King <linux@armlinux.org.uk>,
Petr Machata <petrm@nvidia.com>, Cooper Lees <me@cooperlees.com>,
Ido Schimmel <idosch@nvidia.com>,
Matt Johnston <matt@codeconstruct.com.au>,
linux-kernel@vger.kernel.org, netdev@vger.kernel.org,
bridge@lists.linux-foundation.org
Subject: Re: [PATCH v2 net-next 06/10] net: dsa: Pass VLAN MSTI migration notifications to driver
Date: Wed, 9 Mar 2022 19:03:50 +0200 [thread overview]
Message-ID: <20220309170350.fzp3d6jjpiskdhqv@skbuf> (raw)
In-Reply-To: <87pmmvm8ll.fsf@waldekranz.com>
On Wed, Mar 09, 2022 at 04:47:02PM +0100, Tobias Waldekranz wrote:
> >> +int dsa_port_vlan_msti(struct dsa_port *dp, const struct switchdev_attr *attr)
> >> +{
> >> + struct dsa_switch *ds = dp->ds;
> >> +
> >> + if (!ds->ops->vlan_msti_set)
> >> + return -EOPNOTSUPP;
> >> +
> >> + return ds->ops->vlan_msti_set(ds, attr);
> >
> > I guess this doesn't need to be a cross-chip notifier event for all
> > switches, because replication to all bridge ports is handled by
> > switchdev_handle_port_attr_set(). Ok. But isn't it called too many times
> > per switch?
>
> It is certainly called more times than necessary. But I'm not aware of
> any way to limit it. Just as with other bridge-global settings like
> ageing timeout, the bridge will just replicate the event to each port,
> not knowing whether some of them belong to the same underlying ASIC or
> not.
>
> We could leverage hwdoms in the bridge to figure that out, but then:
Hmm, uncalled for. Also, not sure how it helps (it just plain doesn't
work, as you've pointed out below yourself).
>
> - Drivers that do not implement forward offloading would miss out on
> this optimization. Unfortunate but not a big deal.
> - Since DSA presents multi-chip trees as a single switchdev, the DSA
> layer would have to replicate the event out to each device. Doable,
> but feels like a series of its own.
I've mentally walked through the alternatives and I don't see a practical
alternative than letting the driver cut out the duplicate calls.
Maybe it's worth raising awareness by adding a comment above the
dsa_switch_ops :: vlan_msti_set definition that drivers should be
prepared to handle such calls.
Case in point, in mv88e6xxx_vlan_msti_set() you could avoid some useless
MDIO transactions (a call to mv88e6xxx_vtu_loadpurge) with a simple
"if (vlan.sid != new_sid)" check. Basically just go through a refcount
bump followed by an immediate drop.
next prev parent reply other threads:[~2022-03-09 17:10 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-01 10:03 [PATCH v2 net-next 00/10] net: bridge: Multiple Spanning Trees Tobias Waldekranz
2022-03-01 10:03 ` [PATCH v2 net-next 01/10] net: bridge: mst: Multiple Spanning Tree (MST) mode Tobias Waldekranz
2022-03-01 23:01 ` Nikolay Aleksandrov
2022-03-07 14:53 ` Tobias Waldekranz
2022-03-03 22:28 ` Vladimir Oltean
2022-03-01 10:03 ` [PATCH v2 net-next 02/10] net: bridge: mst: Allow changing a VLAN's MSTI Tobias Waldekranz
2022-03-03 22:27 ` Vladimir Oltean
2022-03-07 14:54 ` Tobias Waldekranz
2022-03-01 10:03 ` [PATCH v2 net-next 03/10] net: bridge: mst: Support setting and reporting MST port states Tobias Waldekranz
2022-03-01 23:19 ` Nikolay Aleksandrov
2022-03-02 1:53 ` Roopa Prabhu
2022-03-07 15:03 ` Tobias Waldekranz
2022-03-07 15:00 ` Tobias Waldekranz
2022-03-07 15:03 ` Nikolay Aleksandrov
2022-03-01 10:03 ` [PATCH v2 net-next 04/10] net: bridge: mst: Notify switchdev drivers of VLAN MSTI migrations Tobias Waldekranz
2022-03-03 20:59 ` Vladimir Oltean
2022-03-08 8:01 ` Tobias Waldekranz
2022-03-08 17:17 ` Vladimir Oltean
2022-03-09 15:34 ` Tobias Waldekranz
2022-03-01 10:03 ` [PATCH v2 net-next 05/10] net: bridge: mst: Notify switchdev drivers of MST state changes Tobias Waldekranz
2022-03-01 10:03 ` [PATCH v2 net-next 06/10] net: dsa: Pass VLAN MSTI migration notifications to driver Tobias Waldekranz
2022-03-03 22:29 ` Vladimir Oltean
2022-03-09 15:47 ` Tobias Waldekranz
2022-03-09 17:03 ` Vladimir Oltean [this message]
2022-03-01 10:03 ` [PATCH v2 net-next 07/10] net: dsa: Pass MST state changes " Tobias Waldekranz
2022-03-03 22:20 ` Vladimir Oltean
2022-03-10 8:54 ` Tobias Waldekranz
2022-03-10 10:35 ` Vladimir Oltean
2022-03-10 16:05 ` Tobias Waldekranz
2022-03-10 16:18 ` Vladimir Oltean
2022-03-10 22:46 ` Tobias Waldekranz
2022-03-10 23:08 ` Vladimir Oltean
2022-03-10 23:59 ` Tobias Waldekranz
2022-03-11 0:22 ` Vladimir Oltean
2022-03-11 9:01 ` Tobias Waldekranz
2022-03-10 16:20 ` Tobias Waldekranz
2022-03-01 10:03 ` [PATCH v2 net-next 08/10] net: dsa: mv88e6xxx: Disentangle STU from VTU Tobias Waldekranz
2022-03-01 10:03 ` [PATCH v2 net-next 09/10] net: dsa: mv88e6xxx: Export STU as devlink region Tobias Waldekranz
2022-03-01 10:03 ` [PATCH v2 net-next 10/10] net: dsa: mv88e6xxx: MST Offloading Tobias Waldekranz
2022-03-03 22:26 ` Vladimir Oltean
2022-03-10 15:14 ` Tobias Waldekranz
2022-03-10 15:25 ` Vladimir Oltean
2022-03-10 15:33 ` Vladimir Oltean
2022-03-01 16:21 ` [PATCH v2 net-next 00/10] net: bridge: Multiple Spanning Trees Vladimir Oltean
2022-03-01 17:19 ` Stephen Hemminger
2022-03-01 21:20 ` Tobias Waldekranz
2022-03-01 22:30 ` Pavel Šimerda
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