net: bridge: add a flag to avoid refreshing fdb when changing/adding

When we modify or create a new fdb entry sometimes we want to avoid
refreshing its activity in order to track it properly. One example is
when a mac is received from EVPN multi-homing peer by FRR, which doesn't
want to change local activity accounting. It makes it static and sets a
flag to track its activity.
Signed-off-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/uapi/linux/neighbour.h

@@ -191,6 +191,7 @@ enum {
 enum {
 	NFEA_UNSPEC,
 	NFEA_ACTIVITY_NOTIFY,
+	NFEA_DONT_REFRESH,
 	__NFEA_MAX
 };
 #define NFEA_MAX (__NFEA_MAX - 1)

net/bridge/br_fdb.c

@@ -860,6 +860,7 @@ static int fdb_add_entry(struct net_bridge *br, struct net_bridge_port *source,
 			 struct nlattr *nfea_tb[])
 {
 	bool is_sticky = !!(ndm->ndm_flags & NTF_STICKY);
+	bool refresh = !nfea_tb[NFEA_DONT_REFRESH];
 	struct net_bridge_fdb_entry *fdb;
 	u16 state = ndm->ndm_state;
 	bool modified = false;
@@ -937,7 +938,8 @@ static int fdb_add_entry(struct net_bridge *br, struct net_bridge_port *source,
 
 	fdb->used = jiffies;
 	if (modified) {
-		fdb->updated = jiffies;
+		if (refresh)
+			fdb->updated = jiffies;
 		fdb_notify(br, fdb, RTM_NEWNEIGH, true);
 	}
 
@@ -977,6 +979,7 @@ static int __br_fdb_add(struct ndmsg *ndm, struct net_bridge *br,
 
 static const struct nla_policy br_nda_fdb_pol[NFEA_MAX + 1] = {
 	[NFEA_ACTIVITY_NOTIFY]	= { .type = NLA_U8 },
+	[NFEA_DONT_REFRESH]	= { .type = NLA_FLAG },
 };
 
 /* Add new permanent fdb entry with RTM_NEWNEIGH */