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net: bridge: fdb: cache port VLANs in learned entries

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Store the resolved port-VLAN as the destination of dynamically learned FDB
entries. Roaming updates the destination directly, while an existing raw
port destination is conditionally upgraded without generating a spurious
notification. Conditional replacements prevent both this upgrade and a VLAN
deletion fallback from overwriting a concurrent roam.

Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: Nikolay Aleksandrov <razor@blackwall.org>
Link: https://patch.msgid.link/20260930071411.2786201-11-razor@blackwall.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Nikolay Aleksandrov 2026-09-30 10:14:09 +03:00 committed by Jakub Kicinski
parent 941056f919
commit 8009eb405f
2 changed files with 55 additions and 20 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

57
net/bridge/br_fdb.c
View File

@ -385,7 +385,7 @@ void br_fdb_find_delete_local(struct net_bridge *br,
}
static struct net_bridge_fdb_entry *fdb_create(struct net_bridge *br,
struct net_bridge_port *source,
struct net_bridge_dst dst,
const unsigned char *addr,
__u16 vid,
unsigned long flags)
@ -409,7 +409,7 @@ static struct net_bridge_fdb_entry *fdb_create(struct net_bridge *br,
return NULL;
memcpy(fdb->key.addr.addr, addr, ETH_ALEN);
br_fdb_dst_write(fdb, br_port_to_dst(source));
br_fdb_dst_write(fdb, dst);
fdb->key.vlan_id = vid;
fdb->flags = flags;
fdb->updated = fdb->used = jiffies;
@ -448,7 +448,7 @@ static int fdb_add_local(struct net_bridge *br, struct net_bridge_port *source,
fdb_delete(br, fdb, true);
}
fdb = fdb_create(br, source, addr, vid,
fdb = fdb_create(br, br_port_to_dst(source), addr, vid,
BIT(BR_FDB_LOCAL) | BIT(BR_FDB_STATIC));
if (!fdb)
return -ENOMEM;
@ -907,8 +907,8 @@ void br_fdb_cleanup_by_dst(struct net_bridge *br,
* back to the raw port destination
*/
if (vlan && br_dst_vlan(dst) == vlan)
br_fdb_dst_write(f,
br_port_to_dst(p));
br_fdb_dst_replace(f, dst,
br_port_to_dst(p));
continue;
}
}
@ -997,9 +997,12 @@ static bool __fdb_mark_active(struct net_bridge_fdb_entry *fdb)
static void __fdb_update(struct net_bridge *br,
struct net_bridge_fdb_entry *fdb,
struct net_bridge_port *source,
struct net_bridge_dst dst,
const unsigned char *addr, u16 vid,
unsigned long flags)
{
struct net_bridge_port *old_port;
struct net_bridge_dst old_dst;
bool fdb_modified = false;
unsigned long now;
@ -1017,18 +1020,30 @@ static void __fdb_update(struct net_bridge *br,
fdb_modified = __fdb_mark_active(fdb);
}
old_dst = br_fdb_dst_read(fdb);
old_port = br_dst_port(old_dst);
/* fastpath: update of existing entry */
if (unlikely(source != br_fdb_dst_port(fdb) &&
!test_bit(BR_FDB_STICKY, &fdb->flags))) {
br_switchdev_fdb_notify(br, fdb, RTM_DELNEIGH);
br_fdb_dst_write(fdb, br_port_to_dst(source));
fdb_modified = true;
/* Take over HW learned entry */
if (unlikely(test_bit(BR_FDB_ADDED_BY_EXT_LEARN, &fdb->flags)))
clear_bit(BR_FDB_ADDED_BY_EXT_LEARN, &fdb->flags);
/* Clear locked flag when roaming to an unlocked port */
if (unlikely(test_bit(BR_FDB_LOCKED, &fdb->flags)))
clear_bit(BR_FDB_LOCKED, &fdb->flags);
if (unlikely(!br_dst_equal(dst, old_dst) &&
(source == old_port ||
!test_bit(BR_FDB_STICKY, &fdb->flags)))) {
if (source != old_port) {
br_switchdev_fdb_notify(br, fdb, RTM_DELNEIGH);
br_fdb_dst_write(fdb, dst);
fdb_modified = true;
/* take over HW learned entry */
if (unlikely(test_bit(BR_FDB_ADDED_BY_EXT_LEARN,
&fdb->flags)))
clear_bit(BR_FDB_ADDED_BY_EXT_LEARN,
&fdb->flags);
/* clear locked flag when roaming to an unlocked port */
if (unlikely(test_bit(BR_FDB_LOCKED, &fdb->flags)))
clear_bit(BR_FDB_LOCKED, &fdb->flags);
} else {
/* raw port-to-VLAN promotion shouldn't overwrite a
* concurrent roam to another port
*/
br_fdb_dst_replace(fdb, old_dst, dst);
}
}
if (unlikely(test_bit(BR_FDB_ADDED_BY_USER, &flags))) {
@ -1047,6 +1062,8 @@ void br_fdb_update(struct net_bridge *br, struct net_bridge_port *source,
struct net_bridge_vlan *vlan, const unsigned char *addr,
unsigned long flags)
{
struct net_bridge_dst dst = vlan ? br_vlan_to_dst(vlan) :
br_port_to_dst(source);
struct net_bridge_fdb_entry *fdb;
u16 vid = vlan ? vlan->vid : 0;
@ -1056,10 +1073,10 @@ void br_fdb_update(struct net_bridge *br, struct net_bridge_port *source,
fdb = fdb_find_rcu(&br->fdb_hash_tbl, addr, vid);
if (likely(fdb)) {
__fdb_update(br, fdb, source, addr, vid, flags);
__fdb_update(br, fdb, source, dst, addr, vid, flags);
} else {
spin_lock(&br->hash_lock);
fdb = fdb_create(br, source, addr, vid, flags);
fdb = fdb_create(br, dst, addr, vid, flags);
if (fdb) {
trace_br_fdb_update(br, source, addr, vid, flags);
fdb_notify(br, fdb, RTM_NEWNEIGH, true);
@ -1213,7 +1230,7 @@ static int fdb_add_entry(struct net_bridge *br, struct net_bridge_port *source,
if (!(flags & NLM_F_CREATE))
return -ENOENT;
fdb = fdb_create(br, source, addr, vid,
fdb = fdb_create(br, br_port_to_dst(source), addr, vid,
BIT(BR_FDB_ADDED_BY_USER));
if (!fdb)
return -ENOMEM;
@ -1564,7 +1581,7 @@ int br_fdb_external_learn_add(struct net_bridge *br, struct net_bridge_port *p,
if (locked)
flags |= BIT(BR_FDB_LOCKED);
fdb = fdb_create(br, p, addr, vid, flags);
fdb = fdb_create(br, br_port_to_dst(p), addr, vid, flags);
if (!fdb) {
err = -ENOMEM;
goto err_unlock;

18
net/bridge/br_private.h
View File

@ -694,6 +694,13 @@ static inline void br_dst_write(struct net_bridge_dst *dst,
ACCESS_PRIVATE(&src, value));
}
static inline bool br_dst_equal(struct net_bridge_dst dst1,
struct net_bridge_dst dst2)
{
return ACCESS_PRIVATE(&dst1, value) ==
ACCESS_PRIVATE(&dst2, value);
}
static inline struct net_bridge_dst
br_port_to_dst(const struct net_bridge_port *p)
{
@ -768,6 +775,17 @@ static inline void br_fdb_dst_write(struct net_bridge_fdb_entry *fdb,
br_dst_write(&fdb->dst, dst);
}
static inline bool
br_fdb_dst_replace(struct net_bridge_fdb_entry *fdb,
struct net_bridge_dst old,
struct net_bridge_dst new)
{
unsigned long old_value = ACCESS_PRIVATE(&old, value);
return cmpxchg(&ACCESS_PRIVATE(&fdb->dst, value), old_value,
ACCESS_PRIVATE(&new, value)) == old_value;
}
static inline struct net_bridge_port *
br_fdb_dst_port(const struct net_bridge_fdb_entry *fdb)
{