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net: bridge: mst: Multiple Spanning Tree (MST) mode

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Allow the user to switch from the current per-VLAN STP mode to an MST
mode.

Up to this point, per-VLAN STP states where always isolated from each
other. This is in contrast to the MSTP standard (802.1Q-2018, Clause
13.5), where VLANs are grouped into MST instances (MSTIs), and the
state is managed on a per-MSTI level, rather that at the per-VLAN
level.

Perhaps due to the prevalence of the standard, many switching ASICs
are built after the same model. Therefore, add a corresponding MST
mode to the bridge, which we can later add offloading support for in a
straight-forward way.

For now, all VLANs are fixed to MSTI 0, also called the Common
Spanning Tree (CST). That is, all VLANs will follow the port-global
state.

Upcoming changes will make this actually useful by allowing VLANs to
be mapped to arbitrary MSTIs and allow individual MSTI states to be
changed.

Signed-off-by: Tobias Waldekranz <tobias@waldekranz.com>
Acked-by: Nikolay Aleksandrov <razor@blackwall.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Tobias Waldekranz 2022-03-16 16:08:43 +01:00 committed by Jakub Kicinski
parent 54744510fa
commit ec7328b591
9 changed files with 176 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
include/uapi/linux/if_bridge.h
View File

@ -759,6 +759,7 @@ struct br_mcast_stats {
enum br_boolopt_id {
BR_BOOLOPT_NO_LL_LEARN,
BR_BOOLOPT_MCAST_VLAN_SNOOPING,
BR_BOOLOPT_MST_ENABLE,
BR_BOOLOPT_MAX
};

2
net/bridge/Makefile
View File

@ -20,7 +20,7 @@ obj-$(CONFIG_BRIDGE_NETFILTER) += br_netfilter.o
bridge-$(CONFIG_BRIDGE_IGMP_SNOOPING) += br_multicast.o br_mdb.o br_multicast_eht.o
bridge-$(CONFIG_BRIDGE_VLAN_FILTERING) += br_vlan.o br_vlan_tunnel.o br_vlan_options.o
bridge-$(CONFIG_BRIDGE_VLAN_FILTERING) += br_vlan.o br_vlan_tunnel.o br_vlan_options.o br_mst.o
bridge-$(CONFIG_NET_SWITCHDEV) += br_switchdev.o

5
net/bridge/br.c
View File

@ -265,6 +265,9 @@ int br_boolopt_toggle(struct net_bridge *br, enum br_boolopt_id opt, bool on,
case BR_BOOLOPT_MCAST_VLAN_SNOOPING:
err = br_multicast_toggle_vlan_snooping(br, on, extack);
break;
case BR_BOOLOPT_MST_ENABLE:
err = br_mst_set_enabled(br, on, extack);
break;
default:
/* shouldn't be called with unsupported options */
WARN_ON(1);
@ -281,6 +284,8 @@ int br_boolopt_get(const struct net_bridge *br, enum br_boolopt_id opt)
return br_opt_get(br, BROPT_NO_LL_LEARN);
case BR_BOOLOPT_MCAST_VLAN_SNOOPING:
return br_opt_get(br, BROPT_MCAST_VLAN_SNOOPING_ENABLED);
case BR_BOOLOPT_MST_ENABLE:
return br_opt_get(br, BROPT_MST_ENABLED);
default:
/* shouldn't be called with unsupported options */
WARN_ON(1);

17
net/bridge/br_input.c
View File

@ -78,13 +78,22 @@ int br_handle_frame_finish(struct net *net, struct sock *sk, struct sk_buff *skb
u16 vid = 0;
u8 state;
if (!p || p->state == BR_STATE_DISABLED)
if (!p)
goto drop;
br = p->br;
if (br_mst_is_enabled(br)) {
state = BR_STATE_FORWARDING;
} else {
if (p->state == BR_STATE_DISABLED)
goto drop;
state = p->state;
}
brmctx = &p->br->multicast_ctx;
pmctx = &p->multicast_ctx;
state = p->state;
if (!br_allowed_ingress(p->br, nbp_vlan_group_rcu(p), skb, &vid,
&state, &vlan))
goto out;
@ -370,9 +379,13 @@ static rx_handler_result_t br_handle_frame(struct sk_buff **pskb)
return RX_HANDLER_PASS;
forward:
if (br_mst_is_enabled(p->br))
goto defer_stp_filtering;
switch (p->state) {
case BR_STATE_FORWARDING:
case BR_STATE_LEARNING:
defer_stp_filtering:
if (ether_addr_equal(p->br->dev->dev_addr, dest))
skb->pkt_type = PACKET_HOST;

87
net/bridge/br_mst.c Normal file
View File

@ -0,0 +1,87 @@
// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Bridge Multiple Spanning Tree Support
*
* Authors:
* Tobias Waldekranz <tobias@waldekranz.com>
*/
#include <linux/kernel.h>
#include "br_private.h"
DEFINE_STATIC_KEY_FALSE(br_mst_used);
static void br_mst_vlan_set_state(struct net_bridge_port *p, struct net_bridge_vlan *v,
u8 state)
{
struct net_bridge_vlan_group *vg = nbp_vlan_group(p);
if (v->state == state)
return;
br_vlan_set_state(v, state);
if (v->vid == vg->pvid)
br_vlan_set_pvid_state(vg, state);
}
int br_mst_set_state(struct net_bridge_port *p, u16 msti, u8 state,
struct netlink_ext_ack *extack)
{
struct net_bridge_vlan_group *vg;
struct net_bridge_vlan *v;
vg = nbp_vlan_group(p);
if (!vg)
return 0;
list_for_each_entry(v, &vg->vlan_list, vlist) {
if (v->brvlan->msti != msti)
continue;
br_mst_vlan_set_state(p, v, state);
}
return 0;
}
void br_mst_vlan_init_state(struct net_bridge_vlan *v)
{
/* VLANs always start out in MSTI 0 (CST) */
v->msti = 0;
if (br_vlan_is_master(v))
v->state = BR_STATE_FORWARDING;
else
v->state = v->port->state;
}
int br_mst_set_enabled(struct net_bridge *br, bool on,
struct netlink_ext_ack *extack)
{
struct net_bridge_vlan_group *vg;
struct net_bridge_port *p;
list_for_each_entry(p, &br->port_list, list) {
vg = nbp_vlan_group(p);
if (!vg->num_vlans)
continue;
NL_SET_ERR_MSG(extack,
"MST mode can't be changed while VLANs exist");
return -EBUSY;
}
if (br_opt_get(br, BROPT_MST_ENABLED) == on)
return 0;
if (on)
static_branch_enable(&br_mst_used);
else
static_branch_disable(&br_mst_used);
br_opt_toggle(br, BROPT_MST_ENABLED, on);
return 0;
}

37
net/bridge/br_private.h
View File

@ -178,6 +178,7 @@ enum {
* @br_mcast_ctx: if MASTER flag set, this is the global vlan multicast context
* @port_mcast_ctx: if MASTER flag unset, this is the per-port/vlan multicast
* context
* @msti: if MASTER flag set, this holds the VLANs MST instance
* @vlist: sorted list of VLAN entries
* @rcu: used for entry destruction
*
@ -210,6 +211,8 @@ struct net_bridge_vlan {
struct net_bridge_mcast_port port_mcast_ctx;
};
u16 msti;
struct list_head vlist;
struct rcu_head rcu;
@ -445,6 +448,7 @@ enum net_bridge_opts {
BROPT_NO_LL_LEARN,
BROPT_VLAN_BRIDGE_BINDING,
BROPT_MCAST_VLAN_SNOOPING_ENABLED,
BROPT_MST_ENABLED,
};
struct net_bridge {
@ -1765,6 +1769,39 @@ static inline bool br_vlan_state_allowed(u8 state, bool learn_allow)
}
#endif
/* br_mst.c */
#ifdef CONFIG_BRIDGE_VLAN_FILTERING
DECLARE_STATIC_KEY_FALSE(br_mst_used);
static inline bool br_mst_is_enabled(struct net_bridge *br)
{
return static_branch_unlikely(&br_mst_used) &&
br_opt_get(br, BROPT_MST_ENABLED);
}
int br_mst_set_state(struct net_bridge_port *p, u16 msti, u8 state,
struct netlink_ext_ack *extack);
void br_mst_vlan_init_state(struct net_bridge_vlan *v);
int br_mst_set_enabled(struct net_bridge *br, bool on,
struct netlink_ext_ack *extack);
#else
static inline bool br_mst_is_enabled(struct net_bridge *br)
{
return false;
}
static inline int br_mst_set_state(struct net_bridge_port *p, u16 msti,
u8 state, struct netlink_ext_ack *extack)
{
return -EOPNOTSUPP;
}
static inline int br_mst_set_enabled(struct net_bridge *br, bool on,
struct netlink_ext_ack *extack)
{
return -EOPNOTSUPP;
}
#endif
struct nf_br_ops {
int (*br_dev_xmit_hook)(struct sk_buff *skb);
};

6
net/bridge/br_stp.c
View File

@ -43,6 +43,12 @@ void br_set_state(struct net_bridge_port *p, unsigned int state)
return;
p->state = state;
if (br_opt_get(p->br, BROPT_MST_ENABLED)) {
err = br_mst_set_state(p, 0, state, NULL);
if (err)
br_warn(p->br, "error setting MST state on port %u(%s)\n",
p->port_no, netdev_name(p->dev));
}
err = switchdev_port_attr_set(p->dev, &attr, NULL);
if (err && err != -EOPNOTSUPP)
br_warn(p->br, "error setting offload STP state on port %u(%s)\n",

20
net/bridge/br_vlan.c
View File

@ -226,6 +226,24 @@ static void nbp_vlan_rcu_free(struct rcu_head *rcu)
kfree(v);
}
static void br_vlan_init_state(struct net_bridge_vlan *v)
{
struct net_bridge *br;
if (br_vlan_is_master(v))
br = v->br;
else
br = v->port->br;
if (br_opt_get(br, BROPT_MST_ENABLED)) {
br_mst_vlan_init_state(v);
return;
}
v->state = BR_STATE_FORWARDING;
v->msti = 0;
}
/* This is the shared VLAN add function which works for both ports and bridge
* devices. There are four possible calls to this function in terms of the
* vlan entry type:
@ -322,7 +340,7 @@ static int __vlan_add(struct net_bridge_vlan *v, u16 flags,
}
/* set the state before publishing */
v->state = BR_STATE_FORWARDING;
br_vlan_init_state(v);
err = rhashtable_lookup_insert_fast(&vg->vlan_hash, &v->vnode,
br_vlan_rht_params);

5
net/bridge/br_vlan_options.c
View File

@ -99,6 +99,11 @@ static int br_vlan_modify_state(struct net_bridge_vlan_group *vg,
return -EBUSY;
}
if (br_opt_get(br, BROPT_MST_ENABLED)) {
NL_SET_ERR_MSG_MOD(extack, "Can't modify vlan state directly when MST is enabled");
return -EBUSY;
}
if (v->state == state)
return 0;