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>

1 files changed, 6 insertions, 3 deletions

diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index 327fa4957929..f31b2436cde5 100644
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -4578,9 +4578,10 @@ static int rtnl_fdb_add(struct sk_buff *skb, struct nlmsghdr *nlh,
 	    netif_is_bridge_port(dev)) {
 		struct net_device *br_dev = netdev_master_upper_dev_get(dev);
 		const struct net_device_ops *ops = br_dev->netdev_ops;
+		bool notified = false;
 
 		err = ops->ndo_fdb_add(ndm, tb, dev, addr, vid,
-				       nlh->nlmsg_flags, extack);
+				       nlh->nlmsg_flags, &notified, extack);
 		if (err)
 			goto out;
 		else
@@ -4589,16 +4590,18 @@ static int rtnl_fdb_add(struct sk_buff *skb, struct nlmsghdr *nlh,
 
 	/* Embedded bridge, macvlan, and any other device support */
 	if ((ndm->ndm_flags & NTF_SELF)) {
+		bool notified = false;
+
 		if (dev->netdev_ops->ndo_fdb_add)
 			err = dev->netdev_ops->ndo_fdb_add(ndm, tb, dev, addr,
 							   vid,
 							   nlh->nlmsg_flags,
-							   extack);
+							   &notified, extack);
 		else
 			err = ndo_dflt_fdb_add(ndm, tb, dev, addr, vid,
 					       nlh->nlmsg_flags);
 
-		if (!err) {
+		if (!err && !notified) {
 			rtnl_fdb_notify(dev, addr, vid, RTM_NEWNEIGH,
 					ndm->ndm_state);
 			ndm->ndm_flags &= ~NTF_SELF;