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switchdev: update documentation on FDB ageing_time 

Signed-off-by: Scott Feldman <sfeldma@gmail.com>
Reviewed-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com>
Acked-by: Jiri Pirko <jiri@resnulli.us>
Signed-off-by: David S. Miller <davem@davemloft.net>
hifive-unleashed-5.1
Scott Feldman 2015-09-23 08:39:20 -07:00 committed by David S. Miller
parent dcd45e0649
commit 45ffda75e1
1 changed files with 11 additions and 11 deletions
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22
Documentation/networking/switchdev.txt
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@ -239,20 +239,20 @@ The driver should initialize the attributes to the hardware defaults.
FDB Ageing
^^^^^^^^^^
There are two FDB ageing models supported: 1) ageing by the device, and 2)
ageing by the kernel. Ageing by the device is preferred if many FDB entries
are supported. The driver calls call_switchdev_notifiers(SWITCHDEV_FDB_DEL,
...) to age out the FDB entry. In this model, ageing by the kernel should be
turned off. XXX: how to turn off ageing in kernel on a per-port basis or
otherwise prevent the kernel from ageing out the FDB entry?
The bridge will skip ageing FDB entries marked with NTF_EXT_LEARNED and it is
the responsibility of the port driver/device to age out these entries. If the
port device supports ageing, when the FDB entry expires, it will notify the
driver which in turn will notify the bridge with SWITCHDEV_FDB_DEL. If the
device does not support ageing, the driver can simulate ageing using a
garbage collection timer to monitor FBD entries. Expired entries will be
notified to the bridge using SWITCHDEV_FDB_DEL. See rocker driver for
example of driver running ageing timer.
In the kernel ageing model, the standard bridge ageing mechanism is used to age
out stale FDB entries. To keep an FDB entry "alive", the driver should refresh
the FDB entry by calling call_switchdev_notifiers(SWITCHDEV_FDB_ADD, ...). The
To keep an NTF_EXT_LEARNED entry "alive", the driver should refresh the FDB
entry by calling call_switchdev_notifiers(SWITCHDEV_FDB_ADD, ...). The
notification will reset the FDB entry's last-used time to now. The driver
should rate limit refresh notifications, for example, no more than once a
second. If the FDB entry expires, fdb_delete is called to remove entry from
the device.
second. (The last-used time is visible using the bridge -s fdb option).
STP State Change on Port
^^^^^^^^^^^^^^^^^^^^^^^^