[PATCH net-next 1/6] net: bridge: mdb: add MDB_FLAGS_STREAM_RESERVED flag

[Luke Howard <lukeh@padl.com>]

Add a new MDB entry flag, MDB_FLAGS_STREAM_RESERVED, that userspace
can set on RTM_NEWMDB to mark a multicast destination as belonging
to a reserved stream (e.g. IEEE 802.1Q Stream Reservation Protocol /
IEEE 1722 / TSN). The bridge core does no admission control on the
basis of the flag; it is metadata propagated through switchdev to
hardware drivers that can themselves enforce admission of AVB / SR
priority traffic only to flagged destinations.

The flag is settable via the new nested attribute MDBE_ATTR_FLAGS
(NLA_U32 bitmask, validated against MDB_FLAGS_SETTABLE_MASK), and is
reflected in dump output via br_mdb_entry.flags as is done today for
the OFFLOAD/BLOCKED/STAR_EXCL flags.

Assisted-by: Claude:claude-4.7-opus
Signed-off-by: Luke Howard <lukeh@padl.com>
---
 include/net/switchdev.h        |  4 ++++
 include/uapi/linux/if_bridge.h |  2 ++
 net/bridge/br_mdb.c            | 12 ++++++++++++
 net/bridge/br_private.h        |  2 ++
 net/bridge/br_switchdev.c      | 17 +++++++++++------
 5 files changed, 31 insertions(+), 6 deletions(-)

diff --git a/include/net/switchdev.h b/include/net/switchdev.h
index ee500706496b0..03d176708b768 100644
--- a/include/net/switchdev.h
+++ b/include/net/switchdev.h
@@ -111,10 +111,14 @@ struct switchdev_obj_port_vlan {
 	container_of((OBJ), struct switchdev_obj_port_vlan, obj)
 
 /* SWITCHDEV_OBJ_ID_PORT_MDB */
+
+#define SWITCHDEV_MDB_F_STREAM_RESERVED		BIT(0)
+
 struct switchdev_obj_port_mdb {
 	struct switchdev_obj obj;
 	unsigned char addr[ETH_ALEN];
 	u16 vid;
+	u32 flags;
 };
 
 #define SWITCHDEV_OBJ_PORT_MDB(OBJ) \
diff --git a/include/uapi/linux/if_bridge.h b/include/uapi/linux/if_bridge.h
index 21a700c02ef76..51ec314994bec 100644
--- a/include/uapi/linux/if_bridge.h
+++ b/include/uapi/linux/if_bridge.h
@@ -705,6 +705,7 @@ struct br_mdb_entry {
 #define MDB_FLAGS_STAR_EXCL		(1 << 2)
 #define MDB_FLAGS_BLOCKED		(1 << 3)
 #define MDB_FLAGS_OFFLOAD_FAILED	(1 << 4)
+#define MDB_FLAGS_STREAM_RESERVED	(1 << 5)
 	__u8 flags;
 	__u16 vid;
 	struct {
@@ -760,6 +761,7 @@ enum {
 	MDBE_ATTR_IFINDEX,
 	MDBE_ATTR_SRC_VNI,
 	MDBE_ATTR_STATE_MASK,
+	MDBE_ATTR_FLAGS,
 	__MDBE_ATTR_MAX,
 };
 #define MDBE_ATTR_MAX (__MDBE_ATTR_MAX - 1)
diff --git a/net/bridge/br_mdb.c b/net/bridge/br_mdb.c
index e0c7020b12f5f..1320ccd81b0a1 100644
--- a/net/bridge/br_mdb.c
+++ b/net/bridge/br_mdb.c
@@ -146,6 +146,8 @@ static void __mdb_entry_fill_flags(struct br_mdb_entry *e, unsigned char flags)
 		e->flags |= MDB_FLAGS_BLOCKED;
 	if (flags & MDB_PG_FLAGS_OFFLOAD_FAILED)
 		e->flags |= MDB_FLAGS_OFFLOAD_FAILED;
+	if (flags & MDB_PG_FLAGS_STREAM_RESERVED)
+		e->flags |= MDB_FLAGS_STREAM_RESERVED;
 }
 
 static void __mdb_entry_to_br_ip(struct br_mdb_entry *entry, struct br_ip *ip,
@@ -664,6 +666,7 @@ static const struct nla_policy br_mdbe_attrs_pol[MDBE_ATTR_MAX + 1] = {
 						  MCAST_INCLUDE),
 	[MDBE_ATTR_SRC_LIST] = NLA_POLICY_NESTED(br_mdbe_src_list_pol),
 	[MDBE_ATTR_RTPROT] = NLA_POLICY_MIN(NLA_U8, RTPROT_STATIC),
+	[MDBE_ATTR_FLAGS] = NLA_POLICY_MASK(NLA_U32, MDB_FLAGS_STREAM_RESERVED),
 };
 
 static bool is_valid_mdb_source(struct nlattr *attr, __be16 proto,
@@ -1072,6 +1075,8 @@ static int br_mdb_add_group(const struct br_mdb_config *cfg,
 	if (entry->state == MDB_PERMANENT)
 		flags |= MDB_PG_FLAGS_PERMANENT;
 
+	flags |= cfg->pg_flags;
+
 	if (br_multicast_is_star_g(&group))
 		return br_mdb_add_group_star_g(cfg, mp, brmctx, flags, extack);
 	else
@@ -1225,6 +1230,13 @@ static int br_mdb_config_attrs_init(struct nlattr *set_attrs,
 		cfg->rt_protocol = nla_get_u8(mdb_attrs[MDBE_ATTR_RTPROT]);
 	}
 
+	if (mdb_attrs[MDBE_ATTR_FLAGS]) {
+		u32 user_flags = nla_get_u32(mdb_attrs[MDBE_ATTR_FLAGS]);
+
+		if (user_flags & MDB_FLAGS_STREAM_RESERVED)
+			cfg->pg_flags |= MDB_PG_FLAGS_STREAM_RESERVED;
+	}
+
 	return 0;
 }
 
diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h
index 02671e648dac7..b9ee19448e38b 100644
--- a/net/bridge/br_private.h
+++ b/net/bridge/br_private.h
@@ -111,6 +111,7 @@ struct br_mdb_config {
 	struct br_mdb_src_entry		*src_entries;
 	int				num_src_entries;
 	u8				rt_protocol;
+	unsigned char			pg_flags;
 };
 #endif
 
@@ -317,6 +318,7 @@ struct net_bridge_fdb_flush_desc {
 #define MDB_PG_FLAGS_STAR_EXCL		BIT(3)
 #define MDB_PG_FLAGS_BLOCKED		BIT(4)
 #define MDB_PG_FLAGS_OFFLOAD_FAILED	BIT(5)
+#define MDB_PG_FLAGS_STREAM_RESERVED	BIT(6)
 
 #define PG_SRC_ENT_LIMIT	32
 
diff --git a/net/bridge/br_switchdev.c b/net/bridge/br_switchdev.c
index 18b558a931ad9..bc05cda2f5350 100644
--- a/net/bridge/br_switchdev.c
+++ b/net/bridge/br_switchdev.c
@@ -548,7 +548,8 @@ static void br_switchdev_mdb_complete(struct net_device *dev, int err, void *pri
 }
 
 static void br_switchdev_mdb_populate(struct switchdev_obj_port_mdb *mdb,
-				      const struct net_bridge_mdb_entry *mp)
+				      const struct net_bridge_mdb_entry *mp,
+				      const struct net_bridge_port_group *pg)
 {
 	if (mp->addr.proto == htons(ETH_P_IP))
 		ip_eth_mc_map(mp->addr.dst.ip4, mdb->addr);
@@ -560,6 +561,9 @@ static void br_switchdev_mdb_populate(struct switchdev_obj_port_mdb *mdb,
 		ether_addr_copy(mdb->addr, mp->addr.dst.mac_addr);
 
 	mdb->vid = mp->addr.vid;
+	mdb->flags = 0;
+	if (pg && (pg->flags & MDB_PG_FLAGS_STREAM_RESERVED))
+		mdb->flags |= SWITCHDEV_MDB_F_STREAM_RESERVED;
 }
 
 static void br_switchdev_host_mdb_one(struct net_device *dev,
@@ -575,7 +579,7 @@ static void br_switchdev_host_mdb_one(struct net_device *dev,
 		},
 	};
 
-	br_switchdev_mdb_populate(&mdb, mp);
+	br_switchdev_mdb_populate(&mdb, mp, NULL);
 
 	switch (type) {
 	case RTM_NEWMDB:
@@ -622,6 +626,7 @@ static int br_switchdev_mdb_queue_one(struct list_head *mdb_list,
 				      unsigned long action,
 				      enum switchdev_obj_id id,
 				      const struct net_bridge_mdb_entry *mp,
+				      const struct net_bridge_port_group *pg,
 				      struct net_device *orig_dev)
 {
 	struct switchdev_obj_port_mdb mdb = {
@@ -632,7 +637,7 @@ static int br_switchdev_mdb_queue_one(struct list_head *mdb_list,
 	};
 	struct switchdev_obj_port_mdb *pmdb;
 
-	br_switchdev_mdb_populate(&mdb, mp);
+	br_switchdev_mdb_populate(&mdb, mp, pg);
 
 	if (action == SWITCHDEV_PORT_OBJ_ADD &&
 	    switchdev_port_obj_act_is_deferred(dev, action, &mdb.obj)) {
@@ -671,7 +676,7 @@ void br_switchdev_mdb_notify(struct net_device *dev,
 	if (!pg)
 		return br_switchdev_host_mdb(dev, mp, type);
 
-	br_switchdev_mdb_populate(&mdb, mp);
+	br_switchdev_mdb_populate(&mdb, mp, pg);
 
 	mdb.obj.orig_dev = pg->key.port->dev;
 	switch (type) {
@@ -740,7 +745,7 @@ br_switchdev_mdb_replay(struct net_device *br_dev, struct net_device *dev,
 		if (mp->host_joined) {
 			err = br_switchdev_mdb_queue_one(&mdb_list, dev, action,
 							 SWITCHDEV_OBJ_ID_HOST_MDB,
-							 mp, br_dev);
+							 mp, NULL, br_dev);
 			if (err) {
 				spin_unlock_bh(&br->multicast_lock);
 				goto out_free_mdb;
@@ -754,7 +759,7 @@ br_switchdev_mdb_replay(struct net_device *br_dev, struct net_device *dev,
 
 			err = br_switchdev_mdb_queue_one(&mdb_list, dev, action,
 							 SWITCHDEV_OBJ_ID_PORT_MDB,
-							 mp, dev);
+							 mp, p, dev);
 			if (err) {
 				spin_unlock_bh(&br->multicast_lock);
 				goto out_free_mdb;
-- 
2.43.0