From: Nikolay Aleksandrov <razor@blackwall.org>
To: netdev@vger.kernel.org
Cc: idosch@nvidia.com, davem@davemloft.net, edumazet@google.com,
kuba@kernel.org, pabeni@redhat.com, horms@kernel.org,
bridge@lists.linux.dev, Nikolay Aleksandrov <razor@blackwall.org>
Subject: [PATCH net-next 10/12] net: bridge: fdb: cache port VLANs in learned entries
Date: Wed, 30 Sep 2026 10:14:09 +0300 [thread overview]
Message-ID: <20260930071411.2786201-11-razor@blackwall.org> (raw)
In-Reply-To: <20260930071411.2786201-1-razor@blackwall.org>
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>
---
net/bridge/br_fdb.c | 57 ++++++++++++++++++++++++++---------------
net/bridge/br_private.h | 18 +++++++++++++
2 files changed, 55 insertions(+), 20 deletions(-)
diff --git a/net/bridge/br_fdb.c b/net/bridge/br_fdb.c
index b87c6f8875da..5664f3d649fa 100644
--- a/net/bridge/br_fdb.c
+++ b/net/bridge/br_fdb.c
@@ -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;
diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h
index 951b6ac5f484..a1c5b1abc1ef 100644
--- a/net/bridge/br_private.h
+++ b/net/bridge/br_private.h
@@ -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)
{
--
2.47.3
next prev parent reply other threads:[~2026-09-30 7:15 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-30 7:13 [PATCH net-next 00/12] net: bridge: vlan: optimize standard fdb fwding path Nikolay Aleksandrov
2026-09-30 7:14 ` [PATCH net-next 01/12] net: bridge: introduce a bridge destination type Nikolay Aleksandrov
2026-10-01 7:24 ` Nikolay Aleksandrov
2026-10-02 19:45 ` Jakub Kicinski
2026-10-02 20:09 ` Nikolay Aleksandrov
2026-10-02 20:18 ` Jakub Kicinski
2026-09-30 7:14 ` [PATCH net-next 02/12] net: bridge: use net_bridge_dst for fdb destinations Nikolay Aleksandrov
2026-09-30 7:14 ` [PATCH net-next 03/12] net: bridge: add VLAN support to bridge destinations Nikolay Aleksandrov
2026-10-01 11:59 ` netdev-bot+sashiko
2026-10-01 12:03 ` Nikolay Aleksandrov
2026-09-30 7:14 ` [PATCH net-next 04/12] net: bridge: vlan: return VLAN entries from ingress helpers Nikolay Aleksandrov
2026-09-30 7:14 ` [PATCH net-next 05/12] net: bridge: fdb: pass VLAN entries to learning updates Nikolay Aleksandrov
2026-09-30 7:14 ` [PATCH net-next 06/12] net: bridge: fdb: consolidate port-VLAN cleanup Nikolay Aleksandrov
2026-10-01 11:59 ` netdev-bot+sashiko
2026-10-01 12:05 ` Nikolay Aleksandrov
2026-09-30 7:14 ` [PATCH net-next 07/12] net: bridge: vlan: split unpublishing from deletion Nikolay Aleksandrov
2026-09-30 7:14 ` [PATCH net-next 08/12] net: bridge: vlan: quiesce readers before freeing port VLANs Nikolay Aleksandrov
2026-10-01 7:28 ` Nikolay Aleksandrov
2026-10-01 11:59 ` netdev-bot+sashiko
2026-10-01 12:07 ` Nikolay Aleksandrov
2026-10-02 19:50 ` Jakub Kicinski
2026-10-02 19:59 ` Nikolay Aleksandrov
2026-09-30 7:14 ` [PATCH net-next 09/12] net: bridge: fdb: factor out existing entry updates Nikolay Aleksandrov
2026-09-30 7:14 ` Nikolay Aleksandrov [this message]
2026-09-30 7:14 ` [PATCH net-next 11/12] net: bridge: fdb: cache VLAN destinations in configured entries Nikolay Aleksandrov
2026-10-01 7:36 ` Nikolay Aleksandrov
2026-09-30 7:14 ` [PATCH net-next 12/12] net: bridge: fdb: avoid VLAN lookups in unicast forwarding Nikolay Aleksandrov
2026-10-02 20:00 ` [PATCH net-next 00/12] net: bridge: vlan: optimize standard fdb fwding path patchwork-bot+netdevbpf
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