1 files changed, 41 insertions, 0 deletions
diff --git a/net/bridge/br_multicast.c b/net/bridge/br_multicast.c
index c7a1095..2559fb5 100644
--- a/net/bridge/br_multicast.c
+++ b/net/bridge/br_multicast.c
@@ -15,6 +15,7 @@
 #include <linux/igmp.h>
 #include <linux/jhash.h>
 #include <linux/kernel.h>
+#include <linux/log2.h>
 #include <linux/netdevice.h>
 #include <linux/netfilter_bridge.h>
 #include <linux/random.h>
@@ -1261,3 +1262,43 @@ unlock:
 
 	return err;
 }
+
+int br_multicast_set_hash_max(struct net_bridge *br, unsigned long val)
+{
+	int err = -ENOENT;
+	u32 old;
+
+	spin_lock(&br->multicast_lock);
+	if (!netif_running(br->dev))
+		goto unlock;
+
+	err = -EINVAL;
+	if (!is_power_of_2(val))
+		goto unlock;
+	if (br->mdb && val < br->mdb->size)
+		goto unlock;
+
+	err = 0;
+
+	old = br->hash_max;
+	br->hash_max = val;
+
+	if (br->mdb) {
+		if (br->mdb->old) {
+			err = -EEXIST;
+rollback:
+			br->hash_max = old;
+			goto unlock;
+		}
+
+		err = br_mdb_rehash(&br->mdb, br->hash_max,
+				    br->hash_elasticity);
+		if (err)
+			goto rollback;
+	}
+
+unlock:
+	spin_unlock(&br->multicast_lock);
+
+	return err;
+}