net: bridge: increase multicast's default maximum number of entries

bridge's default hash_max was 512 which is rather conservative, now that
we're using the generic rhashtable API which autoshrinks let's increase
it to 4096 and move it to a define in br_private.h.
Signed-off-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/bridge/br_multicast.c

@@ -1741,7 +1741,7 @@ static void br_ip6_multicast_query_expired(struct timer_list *t)
 
 void br_multicast_init(struct net_bridge *br)
 {
-	br->hash_max = 512;
+	br->hash_max = BR_MULTICAST_DEFAULT_HASH_MAX;
 
 	br->multicast_router = MDB_RTR_TYPE_TEMP_QUERY;
 	br->multicast_last_member_count = 2;

net/bridge/br_private.h

@@ -31,6 +31,8 @@
 #define BR_PORT_BITS	10
 #define BR_MAX_PORTS	(1<<BR_PORT_BITS)
 
+#define BR_MULTICAST_DEFAULT_HASH_MAX 4096
+
 #define BR_VERSION	"2.3"
 
 /* Control of forwarding link local multicast */