1 files changed, 26 insertions, 15 deletions

diff --git a/net/batman-adv/hard-interface.c b/net/batman-adv/hard-interface.c
index c5f871f218c6..c60d3ed40257 100644
--- a/net/batman-adv/hard-interface.c
+++ b/net/batman-adv/hard-interface.c
@@ -266,16 +266,9 @@ static void batadv_check_known_mac_addr(const struct net_device *net_dev)
 
 int batadv_hardif_min_mtu(struct net_device *soft_iface)
 {
-        const struct batadv_priv *bat_priv = netdev_priv(soft_iface);
+        struct batadv_priv *bat_priv = netdev_priv(soft_iface);
         const struct batadv_hard_iface *hard_iface;
-        /* allow big frames if all devices are capable to do so
-         * (have MTU > 1500 + batadv_max_header_len())
-         */
         int min_mtu = ETH_DATA_LEN;
-        int max_header_len = batadv_max_header_len();
-
-        if (atomic_read(&bat_priv->fragmentation))
-                goto out;
 
         rcu_read_lock();
         list_for_each_entry_rcu(hard_iface, &batadv_hardif_list, list) {
@@ -286,22 +279,40 @@ int batadv_hardif_min_mtu(struct net_device *soft_iface)
                 if (hard_iface->soft_iface != soft_iface)
                         continue;
 
-                min_mtu = min_t(int, hard_iface->net_dev->mtu - max_header_len,
-                                min_mtu);
+                min_mtu = min_t(int, hard_iface->net_dev->mtu, min_mtu);
         }
         rcu_read_unlock();
+
+        atomic_set(&bat_priv->packet_size_max, min_mtu);
+
+        if (atomic_read(&bat_priv->fragmentation) == 0)
+                goto out;
+
+        /* with fragmentation enabled the maximum size of internally generated
+         * packets such as translation table exchanges or tvlv containers, etc
+         * has to be calculated
+         */
+        min_mtu = min_t(int, min_mtu, BATADV_FRAG_MAX_FRAG_SIZE);
+        min_mtu -= sizeof(struct batadv_frag_packet);
+        min_mtu *= BATADV_FRAG_MAX_FRAGMENTS;
+        atomic_set(&bat_priv->packet_size_max, min_mtu);
+
+        /* with fragmentation enabled we can fragment external packets easily */
+        min_mtu = min_t(int, min_mtu, ETH_DATA_LEN);
+
 out:
-        return min_mtu;
+        return min_mtu - batadv_max_header_len();
 }
 
 /* adjusts the MTU if a new interface with a smaller MTU appeared. */
 void batadv_update_min_mtu(struct net_device *soft_iface)
 {
-        int min_mtu;
+        soft_iface->mtu = batadv_hardif_min_mtu(soft_iface);
 
-        min_mtu = batadv_hardif_min_mtu(soft_iface);
-        if (soft_iface->mtu != min_mtu)
-                soft_iface->mtu = min_mtu;
+        /* Check if the local translate table should be cleaned up to match a
+         * new (and smaller) MTU.
+         */
+        batadv_tt_local_resize_to_mtu(soft_iface);
 }
 
 static void