net: bridge: mdb: dump host-joined entries as well

Currently we dump only the port mdb entries but we can have host-joined
entries on the bridge itself and they should be treated as normal temp
mdbs, they're already notified:
$ bridge monitor all
[MDB]dev br0 port br0 grp ff02::8 temp

The group will not be shown in the bridge mdb output, but it takes 1 slot
and it's timing out. If it's only host-joined then the mdb show output
can even be empty.

After this patch we show the host-joined groups:
$ bridge mdb show
dev br0 port br0 grp ff02::8 temp
Signed-off-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/bridge/br_mdb.c

@@ -78,22 +78,35 @@ static void __mdb_entry_to_br_ip(struct br_mdb_entry *entry, struct br_ip *ip)
 }
 
 static int __mdb_fill_info(struct sk_buff *skb,
+			   struct net_bridge_mdb_entry *mp,
 			   struct net_bridge_port_group *p)
 {
+	struct timer_list *mtimer;
 	struct nlattr *nest_ent;
 	struct br_mdb_entry e;
+	u8 flags = 0;
+	int ifindex;
 
 	memset(&e, 0, sizeof(e));
-	__mdb_entry_fill_flags(&e, p->flags);
-	e.ifindex = p->port->dev->ifindex;
-	e.vid = p->addr.vid;
-	if (p->addr.proto == htons(ETH_P_IP))
-		e.addr.u.ip4 = p->addr.u.ip4;
+	if (p) {
+		ifindex = p->port->dev->ifindex;
+		mtimer = &p->timer;
+		flags = p->flags;
+	} else {
+		ifindex = mp->br->dev->ifindex;
+		mtimer = &mp->timer;
+	}
+
+	__mdb_entry_fill_flags(&e, flags);
+	e.ifindex = ifindex;
+	e.vid = mp->addr.vid;
+	if (mp->addr.proto == htons(ETH_P_IP))
+		e.addr.u.ip4 = mp->addr.u.ip4;
 #if IS_ENABLED(CONFIG_IPV6)
-	if (p->addr.proto == htons(ETH_P_IPV6))
-		e.addr.u.ip6 = p->addr.u.ip6;
+	if (mp->addr.proto == htons(ETH_P_IPV6))
+		e.addr.u.ip6 = mp->addr.u.ip6;
 #endif
-	e.addr.proto = p->addr.proto;
+	e.addr.proto = mp->addr.proto;
 	nest_ent = nla_nest_start_noflag(skb,
 					 MDBA_MDB_ENTRY_INFO);
 	if (!nest_ent)
@@ -102,7 +115,7 @@ static int __mdb_fill_info(struct sk_buff *skb,
 	if (nla_put_nohdr(skb, sizeof(e), &e) ||
 	    nla_put_u32(skb,
 			MDBA_MDB_EATTR_TIMER,
-			br_timer_value(&p->timer))) {
+			br_timer_value(mtimer))) {
 		nla_nest_cancel(skb, nest_ent);
 		return -EMSGSIZE;
 	}
@@ -139,12 +152,20 @@ static int br_mdb_fill_info(struct sk_buff *skb, struct netlink_callback *cb,
 			break;
 		}
 
+		if (mp->host_joined) {
+			err = __mdb_fill_info(skb, mp, NULL);
+			if (err) {
+				nla_nest_cancel(skb, nest2);
+				break;
+			}
+		}
+
 		for (pp = &mp->ports; (p = rcu_dereference(*pp)) != NULL;
 		      pp = &p->next) {
 			if (!p->port)
 				continue;
 
-			err = __mdb_fill_info(skb, p);
+			err = __mdb_fill_info(skb, mp, p);
 			if (err) {
 				nla_nest_cancel(skb, nest2);
 				goto out;