linux/net/dsa/switch.c
Vladimir Oltean bfcb813203 net: dsa: configure the MTU for switch ports
It is useful be able to configure port policers on a switch to accept
frames of various sizes:

- Increase the MTU for better throughput from the default of 1500 if it
  is known that there is no 10/100 Mbps device in the network.
- Decrease the MTU to limit the latency of high-priority frames under
  congestion, or work around various network segments that add extra
  headers to packets which can't be fragmented.

For DSA slave ports, this is mostly a pass-through callback, called
through the regular ndo ops and at probe time (to ensure consistency
across all supported switches).

The CPU port is called with an MTU equal to the largest configured MTU
of the slave ports. The assumption is that the user might want to
sustain a bidirectional conversation with a partner over any switch
port.

The DSA master is configured the same as the CPU port, plus the tagger
overhead. Since the MTU is by definition L2 payload (sans Ethernet
header), it is up to each individual driver to figure out if it needs to
do anything special for its frame tags on the CPU port (it shouldn't
except in special cases). So the MTU does not contain the tagger
overhead on the CPU port.
However the MTU of the DSA master, minus the tagger overhead, is used as
a proxy for the MTU of the CPU port, which does not have a net device.
This is to avoid uselessly calling the .change_mtu function on the CPU
port when nothing should change.

So it is safe to assume that the DSA master and the CPU port MTUs are
apart by exactly the tagger's overhead in bytes.

Some changes were made around dsa_master_set_mtu(), function which was
now removed, for 2 reasons:
  - dev_set_mtu() already calls dev_validate_mtu(), so it's redundant to
    do the same thing in DSA
  - __dev_set_mtu() returns 0 if ops->ndo_change_mtu is an absent method
That is to say, there's no need for this function in DSA, we can safely
call dev_set_mtu() directly, take the rtnl lock when necessary, and just
propagate whatever errors get reported (since the user probably wants to
be informed).

Some inspiration (mainly in the MTU DSA notifier) was taken from a
vaguely similar patch from Murali and Florian, who are credited as
co-developers down below.

Co-developed-by: Murali Krishna Policharla <murali.policharla@broadcom.com>
Signed-off-by: Murali Krishna Policharla <murali.policharla@broadcom.com>
Co-developed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2020-03-27 16:07:24 -07:00

399 lines
9.7 KiB
C

// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Handling of a single switch chip, part of a switch fabric
*
* Copyright (c) 2017 Savoir-faire Linux Inc.
* Vivien Didelot <vivien.didelot@savoirfairelinux.com>
*/
#include <linux/if_bridge.h>
#include <linux/netdevice.h>
#include <linux/notifier.h>
#include <linux/if_vlan.h>
#include <net/switchdev.h>
#include "dsa_priv.h"
static unsigned int dsa_switch_fastest_ageing_time(struct dsa_switch *ds,
unsigned int ageing_time)
{
int i;
for (i = 0; i < ds->num_ports; ++i) {
struct dsa_port *dp = dsa_to_port(ds, i);
if (dp->ageing_time && dp->ageing_time < ageing_time)
ageing_time = dp->ageing_time;
}
return ageing_time;
}
static int dsa_switch_ageing_time(struct dsa_switch *ds,
struct dsa_notifier_ageing_time_info *info)
{
unsigned int ageing_time = info->ageing_time;
struct switchdev_trans *trans = info->trans;
if (switchdev_trans_ph_prepare(trans)) {
if (ds->ageing_time_min && ageing_time < ds->ageing_time_min)
return -ERANGE;
if (ds->ageing_time_max && ageing_time > ds->ageing_time_max)
return -ERANGE;
return 0;
}
/* Program the fastest ageing time in case of multiple bridges */
ageing_time = dsa_switch_fastest_ageing_time(ds, ageing_time);
if (ds->ops->set_ageing_time)
return ds->ops->set_ageing_time(ds, ageing_time);
return 0;
}
static bool dsa_switch_mtu_match(struct dsa_switch *ds, int port,
struct dsa_notifier_mtu_info *info)
{
if (ds->index == info->sw_index)
return (port == info->port) || dsa_is_dsa_port(ds, port);
if (!info->propagate_upstream)
return false;
if (dsa_is_dsa_port(ds, port) || dsa_is_cpu_port(ds, port))
return true;
return false;
}
static int dsa_switch_mtu(struct dsa_switch *ds,
struct dsa_notifier_mtu_info *info)
{
int port, ret;
if (!ds->ops->port_change_mtu)
return -EOPNOTSUPP;
for (port = 0; port < ds->num_ports; port++) {
if (dsa_switch_mtu_match(ds, port, info)) {
ret = ds->ops->port_change_mtu(ds, port, info->mtu);
if (ret)
return ret;
}
}
return 0;
}
static int dsa_switch_bridge_join(struct dsa_switch *ds,
struct dsa_notifier_bridge_info *info)
{
if (ds->index == info->sw_index && ds->ops->port_bridge_join)
return ds->ops->port_bridge_join(ds, info->port, info->br);
if (ds->index != info->sw_index && ds->ops->crosschip_bridge_join)
return ds->ops->crosschip_bridge_join(ds, info->sw_index,
info->port, info->br);
return 0;
}
static int dsa_switch_bridge_leave(struct dsa_switch *ds,
struct dsa_notifier_bridge_info *info)
{
bool unset_vlan_filtering = br_vlan_enabled(info->br);
int err, i;
if (ds->index == info->sw_index && ds->ops->port_bridge_leave)
ds->ops->port_bridge_leave(ds, info->port, info->br);
if (ds->index != info->sw_index && ds->ops->crosschip_bridge_leave)
ds->ops->crosschip_bridge_leave(ds, info->sw_index, info->port,
info->br);
/* If the bridge was vlan_filtering, the bridge core doesn't trigger an
* event for changing vlan_filtering setting upon slave ports leaving
* it. That is a good thing, because that lets us handle it and also
* handle the case where the switch's vlan_filtering setting is global
* (not per port). When that happens, the correct moment to trigger the
* vlan_filtering callback is only when the last port left this bridge.
*/
if (unset_vlan_filtering && ds->vlan_filtering_is_global) {
for (i = 0; i < ds->num_ports; i++) {
if (i == info->port)
continue;
if (dsa_to_port(ds, i)->bridge_dev == info->br) {
unset_vlan_filtering = false;
break;
}
}
}
if (unset_vlan_filtering) {
struct switchdev_trans trans = {0};
err = dsa_port_vlan_filtering(dsa_to_port(ds, info->port),
false, &trans);
if (err && err != EOPNOTSUPP)
return err;
}
return 0;
}
static int dsa_switch_fdb_add(struct dsa_switch *ds,
struct dsa_notifier_fdb_info *info)
{
int port = dsa_towards_port(ds, info->sw_index, info->port);
if (!ds->ops->port_fdb_add)
return -EOPNOTSUPP;
return ds->ops->port_fdb_add(ds, port, info->addr, info->vid);
}
static int dsa_switch_fdb_del(struct dsa_switch *ds,
struct dsa_notifier_fdb_info *info)
{
int port = dsa_towards_port(ds, info->sw_index, info->port);
if (!ds->ops->port_fdb_del)
return -EOPNOTSUPP;
return ds->ops->port_fdb_del(ds, port, info->addr, info->vid);
}
static bool dsa_switch_mdb_match(struct dsa_switch *ds, int port,
struct dsa_notifier_mdb_info *info)
{
if (ds->index == info->sw_index && port == info->port)
return true;
if (dsa_is_dsa_port(ds, port))
return true;
return false;
}
static int dsa_switch_mdb_prepare(struct dsa_switch *ds,
struct dsa_notifier_mdb_info *info)
{
int port, err;
if (!ds->ops->port_mdb_prepare || !ds->ops->port_mdb_add)
return -EOPNOTSUPP;
for (port = 0; port < ds->num_ports; port++) {
if (dsa_switch_mdb_match(ds, port, info)) {
err = ds->ops->port_mdb_prepare(ds, port, info->mdb);
if (err)
return err;
}
}
return 0;
}
static int dsa_switch_mdb_add(struct dsa_switch *ds,
struct dsa_notifier_mdb_info *info)
{
int port;
if (switchdev_trans_ph_prepare(info->trans))
return dsa_switch_mdb_prepare(ds, info);
if (!ds->ops->port_mdb_add)
return 0;
for (port = 0; port < ds->num_ports; port++)
if (dsa_switch_mdb_match(ds, port, info))
ds->ops->port_mdb_add(ds, port, info->mdb);
return 0;
}
static int dsa_switch_mdb_del(struct dsa_switch *ds,
struct dsa_notifier_mdb_info *info)
{
if (!ds->ops->port_mdb_del)
return -EOPNOTSUPP;
if (ds->index == info->sw_index)
return ds->ops->port_mdb_del(ds, info->port, info->mdb);
return 0;
}
static int dsa_port_vlan_device_check(struct net_device *vlan_dev,
int vlan_dev_vid,
void *arg)
{
struct switchdev_obj_port_vlan *vlan = arg;
u16 vid;
for (vid = vlan->vid_begin; vid <= vlan->vid_end; ++vid) {
if (vid == vlan_dev_vid)
return -EBUSY;
}
return 0;
}
static int dsa_port_vlan_check(struct dsa_switch *ds, int port,
const struct switchdev_obj_port_vlan *vlan)
{
const struct dsa_port *dp = dsa_to_port(ds, port);
int err = 0;
/* Device is not bridged, let it proceed with the VLAN device
* creation.
*/
if (!dp->bridge_dev)
return err;
/* dsa_slave_vlan_rx_{add,kill}_vid() cannot use the prepare phase and
* already checks whether there is an overlapping bridge VLAN entry
* with the same VID, so here we only need to check that if we are
* adding a bridge VLAN entry there is not an overlapping VLAN device
* claiming that VID.
*/
return vlan_for_each(dp->slave, dsa_port_vlan_device_check,
(void *)vlan);
}
static bool dsa_switch_vlan_match(struct dsa_switch *ds, int port,
struct dsa_notifier_vlan_info *info)
{
if (ds->index == info->sw_index && port == info->port)
return true;
if (dsa_is_dsa_port(ds, port))
return true;
return false;
}
static int dsa_switch_vlan_prepare(struct dsa_switch *ds,
struct dsa_notifier_vlan_info *info)
{
int port, err;
if (!ds->ops->port_vlan_prepare || !ds->ops->port_vlan_add)
return -EOPNOTSUPP;
for (port = 0; port < ds->num_ports; port++) {
if (dsa_switch_vlan_match(ds, port, info)) {
err = dsa_port_vlan_check(ds, port, info->vlan);
if (err)
return err;
err = ds->ops->port_vlan_prepare(ds, port, info->vlan);
if (err)
return err;
}
}
return 0;
}
static int dsa_switch_vlan_add(struct dsa_switch *ds,
struct dsa_notifier_vlan_info *info)
{
int port;
if (switchdev_trans_ph_prepare(info->trans))
return dsa_switch_vlan_prepare(ds, info);
if (!ds->ops->port_vlan_add)
return 0;
for (port = 0; port < ds->num_ports; port++)
if (dsa_switch_vlan_match(ds, port, info))
ds->ops->port_vlan_add(ds, port, info->vlan);
return 0;
}
static int dsa_switch_vlan_del(struct dsa_switch *ds,
struct dsa_notifier_vlan_info *info)
{
if (!ds->ops->port_vlan_del)
return -EOPNOTSUPP;
if (ds->index == info->sw_index)
return ds->ops->port_vlan_del(ds, info->port, info->vlan);
/* Do not deprogram the DSA links as they may be used as conduit
* for other VLAN members in the fabric.
*/
return 0;
}
static int dsa_switch_event(struct notifier_block *nb,
unsigned long event, void *info)
{
struct dsa_switch *ds = container_of(nb, struct dsa_switch, nb);
int err;
switch (event) {
case DSA_NOTIFIER_AGEING_TIME:
err = dsa_switch_ageing_time(ds, info);
break;
case DSA_NOTIFIER_BRIDGE_JOIN:
err = dsa_switch_bridge_join(ds, info);
break;
case DSA_NOTIFIER_BRIDGE_LEAVE:
err = dsa_switch_bridge_leave(ds, info);
break;
case DSA_NOTIFIER_FDB_ADD:
err = dsa_switch_fdb_add(ds, info);
break;
case DSA_NOTIFIER_FDB_DEL:
err = dsa_switch_fdb_del(ds, info);
break;
case DSA_NOTIFIER_MDB_ADD:
err = dsa_switch_mdb_add(ds, info);
break;
case DSA_NOTIFIER_MDB_DEL:
err = dsa_switch_mdb_del(ds, info);
break;
case DSA_NOTIFIER_VLAN_ADD:
err = dsa_switch_vlan_add(ds, info);
break;
case DSA_NOTIFIER_VLAN_DEL:
err = dsa_switch_vlan_del(ds, info);
break;
case DSA_NOTIFIER_MTU:
err = dsa_switch_mtu(ds, info);
break;
default:
err = -EOPNOTSUPP;
break;
}
/* Non-switchdev operations cannot be rolled back. If a DSA driver
* returns an error during the chained call, switch chips may be in an
* inconsistent state.
*/
if (err)
dev_dbg(ds->dev, "breaking chain for DSA event %lu (%d)\n",
event, err);
return notifier_from_errno(err);
}
int dsa_switch_register_notifier(struct dsa_switch *ds)
{
ds->nb.notifier_call = dsa_switch_event;
return raw_notifier_chain_register(&ds->dst->nh, &ds->nb);
}
void dsa_switch_unregister_notifier(struct dsa_switch *ds)
{
int err;
err = raw_notifier_chain_unregister(&ds->dst->nh, &ds->nb);
if (err)
dev_err(ds->dev, "failed to unregister notifier (%d)\n", err);
}