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Diffstat (limited to 'Documentation/networking/switchdev.txt')
| -rw-r--r-- | Documentation/networking/switchdev.txt | 43 |
1 files changed, 31 insertions, 12 deletions
diff --git a/Documentation/networking/switchdev.txt b/Documentation/networking/switchdev.txt index 476df0496686..9f9e2587b347 100644 --- a/Documentation/networking/switchdev.txt +++ b/Documentation/networking/switchdev.txt @@ -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? - -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 +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. + +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 ^^^^^^^^^^^^^^^^^^^^^^^^ @@ -369,3 +369,22 @@ The driver can monitor for updates to arp_tbl using the netevent notifier NETEVENT_NEIGH_UPDATE. The device can be programmed with resolved nexthops for the routes as arp_tbl updates. The driver implements ndo_neigh_destroy to know when arp_tbl neighbor entries are purged from the port. + +Transaction item queue +^^^^^^^^^^^^^^^^^^^^^^ + +For switchdev ops attr_set and obj_add, there is a 2 phase transaction model +used. First phase is to "prepare" anything needed, including various checks, +memory allocation, etc. The goal is to handle the stuff that is not unlikely +to fail here. The second phase is to "commit" the actual changes. + +Switchdev provides an inftrastructure for sharing items (for example memory +allocations) between the two phases. + +The object created by a driver in "prepare" phase and it is queued up by: +switchdev_trans_item_enqueue() +During the "commit" phase, the driver gets the object by: +switchdev_trans_item_dequeue() + +If a transaction is aborted during "prepare" phase, switchdev code will handle +cleanup of the queued-up objects. |