ndo_fdb_add: Add a parameter to report whether notification was sent

Currently when FDB entries are added to or deleted from a VXLAN netdevice,
the VXLAN driver emits one notification, including the VXLAN-specific
attributes. The core however always sends a notification as well, a generic
one. Thus two notifications are unnecessarily sent for these operations. A
similar situation comes up with bridge driver, which also emits
notifications on its own:

 # ip link add name vx type vxlan id 1000 dstport 4789
 # bridge monitor fdb &
 [1] 1981693
 # bridge fdb add de:ad:be:ef:13:37 dev vx self dst 192.0.2.1
 de:ad:be:ef:13:37 dev vx dst 192.0.2.1 self permanent
 de:ad:be:ef:13:37 dev vx self permanent

In order to prevent this duplicity, add a paremeter to ndo_fdb_add,
bool *notified. The flag is primed to false, and if the callee sends a
notification on its own, it sets it to true, thus informing the core that
it should not generate another notification.

Signed-off-by: Petr Machata <petrm@nvidia.com>
Reviewed-by: Amit Cohen <amcohen@nvidia.com>
Reviewed-by: Nikolay Aleksandrov <razor@blackwall.org>
Link: https://patch.msgid.link/cbf6ae8195e85cbf922f8058ce4eba770f3b71ed.1731589511.git.petrm@nvidia.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

2 files changed, 8 insertions, 6 deletions

diff --git a/net/bridge/br_fdb.c b/net/bridge/br_fdb.c
index 77f110035df1..5f29958f3ddd 100644
--- a/net/bridge/br_fdb.c
+++ b/net/bridge/br_fdb.c
@@ -1152,7 +1152,7 @@ static int fdb_add_entry(struct net_bridge *br, struct net_bridge_port *source,
 static int __br_fdb_add(struct ndmsg *ndm, struct net_bridge *br,
 			struct net_bridge_port *p, const unsigned char *addr,
 			u16 nlh_flags, u16 vid, struct nlattr *nfea_tb[],
-			struct netlink_ext_ack *extack)
+			bool *notified, struct netlink_ext_ack *extack)
 {
 	int err = 0;
 
@@ -1183,6 +1183,8 @@ static int __br_fdb_add(struct ndmsg *ndm, struct net_bridge *br,
 		spin_unlock_bh(&br->hash_lock);
 	}
 
+	if (!err)
+		*notified = true;
 	return err;
 }
 
@@ -1195,7 +1197,7 @@ static const struct nla_policy br_nda_fdb_pol[NFEA_MAX + 1] = {
 int br_fdb_add(struct ndmsg *ndm, struct nlattr *tb[],
 	       struct net_device *dev,
 	       const unsigned char *addr, u16 vid, u16 nlh_flags,
-	       struct netlink_ext_ack *extack)
+	       bool *notified, struct netlink_ext_ack *extack)
 {
 	struct nlattr *nfea_tb[NFEA_MAX + 1], *attr;
 	struct net_bridge_vlan_group *vg;
@@ -1258,10 +1260,10 @@ int br_fdb_add(struct ndmsg *ndm, struct nlattr *tb[],
 
 		/* VID was specified, so use it. */
 		err = __br_fdb_add(ndm, br, p, addr, nlh_flags, vid, nfea_tb,
-				   extack);
+				   notified, extack);
 	} else {
 		err = __br_fdb_add(ndm, br, p, addr, nlh_flags, 0, nfea_tb,
-				   extack);
+				   notified, extack);
 		if (err || !vg || !vg->num_vlans)
 			goto out;
 
@@ -1273,7 +1275,7 @@ int br_fdb_add(struct ndmsg *ndm, struct nlattr *tb[],
 			if (!br_vlan_should_use(v))
 				continue;
 			err = __br_fdb_add(ndm, br, p, addr, nlh_flags, v->vid,
-					   nfea_tb, extack);
+					   nfea_tb, notified, extack);
 			if (err)
 				goto out;
 		}
diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h
index 041f6e571a20..ebfc59049ec1 100644
--- a/net/bridge/br_private.h
+++ b/net/bridge/br_private.h
@@ -858,7 +858,7 @@ int br_fdb_delete_bulk(struct nlmsghdr *nlh, struct net_device *dev,
 		       struct netlink_ext_ack *extack);
 int br_fdb_add(struct ndmsg *nlh, struct nlattr *tb[], struct net_device *dev,
 	       const unsigned char *addr, u16 vid, u16 nlh_flags,
-	       struct netlink_ext_ack *extack);
+	       bool *notified, struct netlink_ext_ack *extack);
 int br_fdb_dump(struct sk_buff *skb, struct netlink_callback *cb,
 		struct net_device *dev, struct net_device *fdev, int *idx);
 int br_fdb_get(struct sk_buff *skb, struct nlattr *tb[], struct net_device *dev,