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docs: net: dsa: delete misinformation about -EOPNOTSUPP for FDB/MDB/VLAN

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Returning -EOPNOTSUPP does *NOT* mean anything special.

port_vlan_add() is actually called from 2 code paths, one is
vlan_vid_add() from 8021q module and the other is
br_switchdev_port_vlan_add() from switchdev.

The bridge has a wrapper __vlan_vid_add() which first tries via
switchdev, then if that returns -EOPNOTSUPP, tries again via the VLAN RX
filters in the 8021q module. But DSA doesn't distinguish between one
call path and the other when calling the driver's port_vlan_add(), so if
the driver returns -EOPNOTSUPP to switchdev, it also returns -EOPNOTSUPP
to the 8021q module. And the latter is a hard error.

port_fdb_add() is called from the deferred dsa_owq only, so obviously
its return code isn't propagated anywhere, and cannot be interpreted in
any way.

The return code from port_mdb_add() is propagated to the bridge, but
again, this doesn't do anything special when -EOPNOTSUPP is returned,
but rather, br_switchdev_mdb_notify() returns void.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Vladimir Oltean 2022-07-16 21:53:43 +03:00 committed by David S. Miller
parent ea7006a7aa
commit 6ba1a4aa59
1 changed files with 3 additions and 9 deletions
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12
Documentation/networking/dsa/dsa.rst
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@ -951,9 +951,7 @@ Bridge VLAN filtering
allowed.
- ``port_vlan_add``: bridge layer function invoked when a VLAN is configured
(tagged or untagged) for the given switch port. If the operation is not
supported by the hardware, this function should return ``-EOPNOTSUPP`` to
inform the bridge code to fallback to a software implementation.
(tagged or untagged) for the given switch port..
- ``port_vlan_del``: bridge layer function invoked when a VLAN is removed from the
given switch port
@ -961,9 +959,7 @@ Bridge VLAN filtering
- ``port_fdb_add``: bridge layer function invoked when the bridge wants to install a
Forwarding Database entry, the switch hardware should be programmed with the
specified address in the specified VLAN Id in the forwarding database
associated with this VLAN ID. If the operation is not supported, this
function should return ``-EOPNOTSUPP`` to inform the bridge code to fallback to
a software implementation.
associated with this VLAN ID.
- ``port_fdb_del``: bridge layer function invoked when the bridge wants to remove a
Forwarding Database entry, the switch hardware should be programmed to delete
@ -978,9 +974,7 @@ Bridge VLAN filtering
the ``bridge fdb show`` command.
- ``port_mdb_add``: bridge layer function invoked when the bridge wants to install
a multicast database entry. If the operation is not supported, this function
should return ``-EOPNOTSUPP`` to inform the bridge code to fallback to a
software implementation. The switch hardware should be programmed with the
a multicast database entry. The switch hardware should be programmed with the
specified address in the specified VLAN ID in the forwarding database
associated with this VLAN ID.