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Scott Feldman says:

====================
switchdev: documentation updates

Update the switchdev documentation to clarify that for IPV4 FIB object, the add
op is used for both adding and modifying the FIB entry on the device.

I found a few other white-space and grammer issues to fix, and to clarify the
static FDB ops.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>
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David S. Miller committed Jun 4, 2015
2 parents 9d1dabf + 7616dcb commit 37c8e2b
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95 changes: 52 additions & 43 deletions Documentation/networking/switchdev.txt
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Original file line number Diff line number Diff line change
Expand Up @@ -114,11 +114,11 @@ would be sub-port 0 on port 1 on switch 1.
Switch ID
^^^^^^^^^

The switchdev driver must implement the switchdev op switchdev_port_attr_get for
SWITCHDEV_ATTR_PORT_PARENT_ID for each port netdev, returning the same physical ID
for each port of a switch. The ID must be unique between switches on the same
system. The ID does not need to be unique between switches on different
systems.
The switchdev driver must implement the switchdev op switchdev_port_attr_get
for SWITCHDEV_ATTR_PORT_PARENT_ID for each port netdev, returning the same
physical ID for each port of a switch. The ID must be unique between switches
on the same system. The ID does not need to be unique between switches on
different systems.

The switch ID is used to locate ports on a switch and to know if aggregated
ports belong to the same switch.
Expand All @@ -142,7 +142,7 @@ The port netdevs representing the physical switch ports can be organized into
higher-level switching constructs. The default construct is a standalone
router port, used to offload L3 forwarding. Two or more ports can be bonded
together to form a LAG. Two or more ports (or LAGs) can be bridged to bridge
to L2 networks. VLANs can be applied to sub-divide L2 networks. L2-over-L3
L2 networks. VLANs can be applied to sub-divide L2 networks. L2-over-L3
tunnels can be built on ports. These constructs are built using standard Linux
tools such as the bridge driver, the bonding/team drivers, and netlink-based
tools such as iproute2.
Expand Down Expand Up @@ -177,6 +177,10 @@ entries are installed, for example, using iproute2 bridge cmd:

bridge fdb add ADDR dev DEV [vlan VID] [self]

The driver should use the helper switchdev_port_fdb_xxx ops for ndo_fdb_xxx
ops, and handle add/delete/dump of SWITCHDEV_OBJ_PORT_FDB object using
switchdev_port_obj_xxx ops.

XXX: what should be done if offloading this rule to hardware fails (for
example, due to full capacity in hardware tables) ?

Expand All @@ -194,11 +198,11 @@ in turn, will notify the bridge driver using the switchdev notifier call:

err = call_switchdev_notifiers(val, dev, info);

Where val is SWITCHDEV_FDB_ADD when learning and SWITCHDEV_FDB_DEL when forgetting, and
info points to a struct switchdev_notifier_fdb_info. On SWITCHDEV_FDB_ADD, the bridge
driver will install the FDB entry into the bridge's FDB and mark the entry as
NTF_EXT_LEARNED. The iproute2 bridge command will label these entries
"offload":
Where val is SWITCHDEV_FDB_ADD when learning and SWITCHDEV_FDB_DEL when
forgetting, and info points to a struct switchdev_notifier_fdb_info. On
SWITCHDEV_FDB_ADD, the bridge driver will install the FDB entry into the
bridge's FDB and mark the entry as NTF_EXT_LEARNED. The iproute2 bridge
command will label these entries "offload":

$ bridge fdb
52:54:00:12:35:01 dev sw1p1 master br0 permanent
Expand Down Expand Up @@ -229,18 +233,18 @@ the bridge's FDB. It's possible, but not optimal, to enable learning on the
device port and on the bridge port, and disable learning_sync.

To support learning and learning_sync port attributes, the driver implements
switchdev op switchdev_port_attr_get/set for SWITCHDEV_ATTR_PORT_BRIDGE_FLAGS. The driver
should initialize the attributes to the hardware defaults.
switchdev op switchdev_port_attr_get/set for SWITCHDEV_ATTR_PORT_BRIDGE_FLAGS.
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?
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
Expand All @@ -262,8 +266,8 @@ STP State Change on Port

Internally or with a third-party STP protocol implementation (e.g. mstpd), the
bridge driver maintains the STP state for ports, and will notify the switch
driver of STP state change on a port using the switchdev op switchdev_attr_port_set for
SWITCHDEV_ATTR_PORT_STP_UPDATE.
driver of STP state change on a port using the switchdev op
switchdev_attr_port_set for SWITCHDEV_ATTR_PORT_STP_UPDATE.

State is one of BR_STATE_*. The switch driver can use STP state updates to
update ingress packet filter list for the port. For example, if port is
Expand Down Expand Up @@ -296,33 +300,38 @@ IGMP Snooping
XXX: complete this section


L3 routing
----------
L3 Routing Offload
------------------

Offloading L3 routing requires that device be programmed with FIB entries from
the kernel, with the device doing the FIB lookup and forwarding. The device
does a longest prefix match (LPM) on FIB entries matching route prefix and
forwards the packet to the matching FIB entry's nexthop(s) egress ports. To
program the device, the switchdev driver is called with add/delete ops for IPv4
and IPv6 FIB entries. For IPv4, the driver implements switchdev ops:

int (*switchdev_fib_ipv4_add)(struct net_device *dev,
__be32 dst, int dst_len,
struct fib_info *fi,
u8 tos, u8 type,
u32 nlflags, u32 tb_id);

int (*switchdev_fib_ipv4_del)(struct net_device *dev,
__be32 dst, int dst_len,
struct fib_info *fi,
u8 tos, u8 type,
u32 tb_id);

to add/delete IPv4 dst/dest_len prefix on table tb_id. The *fi structure holds
details on the route and route's nexthops. *dev is one of the port netdevs
mentioned in the routes next hop list. If the output port netdevs referenced
in the route's nexthop list don't all have the same switch ID, the driver is
not called to add/delete the FIB entry.
forwards the packet to the matching FIB entry's nexthop(s) egress ports.

To program the device, the driver implements support for
SWITCHDEV_OBJ_IPV[4|6]_FIB object using switchdev_port_obj_xxx ops.
switchdev_port_obj_add is used for both adding a new FIB entry to the device,
or modifying an existing entry on the device.

XXX: Currently, only SWITCHDEV_OBJ_IPV4_FIB objects are supported.

SWITCHDEV_OBJ_IPV4_FIB object passes:

struct switchdev_obj_ipv4_fib { /* IPV4_FIB */
u32 dst;
int dst_len;
struct fib_info *fi;
u8 tos;
u8 type;
u32 nlflags;
u32 tb_id;
} ipv4_fib;

to add/modify/delete IPv4 dst/dest_len prefix on table tb_id. The *fi
structure holds details on the route and route's nexthops. *dev is one of the
port netdevs mentioned in the routes next hop list. If the output port netdevs
referenced in the route's nexthop list don't all have the same switch ID, the
driver is not called to add/modify/delete the FIB entry.

Routes offloaded to the device are labeled with "offload" in the ip route
listing:
Expand All @@ -340,7 +349,7 @@ listing:
12.0.0.4 via 11.0.0.9 dev sw1p2 proto zebra metric 20 offload
192.168.0.0/24 dev eth0 proto kernel scope link src 192.168.0.15

XXX: add/del IPv6 FIB API
XXX: add/mod/del IPv6 FIB API

Nexthop Resolution
^^^^^^^^^^^^^^^^^^
Expand Down
4 changes: 2 additions & 2 deletions net/switchdev/switchdev.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -803,7 +803,7 @@ static struct net_device *switchdev_get_dev_by_nhs(struct fib_info *fi)
}

/**
* switchdev_fib_ipv4_add - Add IPv4 route entry to switch
* switchdev_fib_ipv4_add - Add/modify switch IPv4 route entry
*
* @dst: route's IPv4 destination address
* @dst_len: destination address length (prefix length)
Expand All @@ -813,7 +813,7 @@ static struct net_device *switchdev_get_dev_by_nhs(struct fib_info *fi)
* @nlflags: netlink flags passed in (NLM_F_*)
* @tb_id: route table ID
*
* Add IPv4 route entry to switch device.
* Add/modify switch IPv4 route entry.
*/
int switchdev_fib_ipv4_add(u32 dst, int dst_len, struct fib_info *fi,
u8 tos, u8 type, u32 nlflags, u32 tb_id)
Expand Down

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