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authorVladimir Oltean <vladimir.oltean@nxp.com>2021-01-09 03:01:47 +0300
committerJakub Kicinski <kuba@kernel.org>2021-01-12 03:00:56 +0300
commit3e85f580e3fc553d1ba21ac01e08659cbd0f66cc (patch)
treef7b4db946a9a5e0541cba5dba9c6a253f3b0c146 /net/switchdev
parentb7a9e0da2d1c954b7c38217a29e002528b90d174 (diff)
downloadlinux-3e85f580e3fc553d1ba21ac01e08659cbd0f66cc.tar.xz
net: dsa: mv88e6xxx: deny vid 0 on the CPU port and DSA links too
mv88e6xxx apparently has a problem offloading VID 0, which the 8021q module tries to install as part of commit ad1afb003939 ("vlan_dev: VLAN 0 should be treated as "no vlan tag" (802.1p packet)"). That mv88e6xxx restriction seems to have been introduced by the "VTU GetNext VID-1 trick to retrieve a single entry" - see commit 2fb5ef09de7c ("net: dsa: mv88e6xxx: extract single VLAN retrieval"). There is one more problem. The mv88e6xxx CPU port and DSA links do not report properly in the prepare phase what are the VLANs that they can offload. They'll say they can offload everything: mv88e6xxx_port_vlan_prepare -> mv88e6xxx_port_check_hw_vlan: /* DSA and CPU ports have to be members of multiple vlans */ if (dsa_is_dsa_port(ds, port) || dsa_is_cpu_port(ds, port)) return 0; Except that if you actually try to commit to it, they'll error out and print this message: [ 32.802438] mv88e6085 d0032004.mdio-mii:12: p9: failed to add VLAN 0t which comes from: mv88e6xxx_port_vlan_add -> mv88e6xxx_port_vlan_join: if (!vid) return -EOPNOTSUPP; What prevents this condition from triggering in real life? The fact that when a DSA_NOTIFIER_VLAN_ADD is emitted, it never targets a DSA link directly. Instead, the notifier will always target either a user port or a CPU port. DSA links just happen to get dragged in by: static bool dsa_switch_vlan_match(struct dsa_switch *ds, int port, struct dsa_notifier_vlan_info *info) { ... if (dsa_is_dsa_port(ds, port)) return true; ... } So for every DSA VLAN notifier, during the prepare phase, it will just so happen that there will be somebody to say "no, don't do that". This will become a problem when the switchdev prepare/commit transactional model goes away. Every port needs to think on its own. DSA links can no longer bluff and rely on the fact that the prepare phase will not go through to the end, because there will be no prepare phase any longer. Fix this issue before it becomes a problem, by having the "vid == 0" check earlier than the check whether we are a CPU port / DSA link or not. Also, the "vid == 0" check becomes unnecessary in the .port_vlan_add callback, so we can remove it. Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com> Reviewed-by: Florian Fainelli <f.fainelli@gmail.com> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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