batman-adv: consider network coding overhead when calculating required mtu

The module prints a warning when the MTU on the hard interface is too
small to transfer payload traffic without fragmentation. The required
MTU is calculated based on the encapsulation header size. If network
coding is compild into the module its header size is taken into
account as well.

Signed-off-by: Marek Lindner <lindner_marek@yahoo.de>
Signed-off-by: Antonio Quartulli <antonio@meshcoding.com>

diff --git a/net/batman-adv/hard-interface.c b/net/batman-adv/hard-interface.c
index 004017c523fa501bfb06446a11df15e58575b632..d564af295db438a399ef5eac70844e34e1aced21 100644 (file)
--- a/net/batman-adv/hard-interface.c
+++ b/net/batman-adv/hard-interface.c
@@ -269,9 +269,10 @@ int batadv_hardif_min_mtu(struct net_device *soft_iface)
        const 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 + BAT_HEADER_LEN)
+        * (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;
@@ -285,8 +286,7 @@ 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 - BATADV_HEADER_LEN,
+               min_mtu = min_t(int, hard_iface->net_dev->mtu - max_header_len,
                                min_mtu);
        }
        rcu_read_unlock();
@@ -380,6 +380,7 @@ int batadv_hardif_enable_interface(struct batadv_hard_iface *hard_iface,
        struct batadv_priv *bat_priv;
        struct net_device *soft_iface, *master;
        __be16 ethertype = htons(ETH_P_BATMAN);
+       int max_header_len = batadv_max_header_len();
        int ret;
 
        if (hard_iface->if_status != BATADV_IF_NOT_IN_USE)
@@ -448,18 +449,18 @@ int batadv_hardif_enable_interface(struct batadv_hard_iface *hard_iface,
                    hard_iface->net_dev->name);
 
        if (atomic_read(&bat_priv->fragmentation) &&
-           hard_iface->net_dev->mtu < ETH_DATA_LEN + BATADV_HEADER_LEN)
+           hard_iface->net_dev->mtu < ETH_DATA_LEN + max_header_len)
                batadv_info(hard_iface->soft_iface,
-                           "The MTU of interface %s is too small (%i) to handle the transport of batman-adv packets. Packets going over this interface will be fragmented on layer2 which could impact the performance. Setting the MTU to %zi would solve the problem.\n",
+                           "The MTU of interface %s is too small (%i) to handle the transport of batman-adv packets. Packets going over this interface will be fragmented on layer2 which could impact the performance. Setting the MTU to %i would solve the problem.\n",
                            hard_iface->net_dev->name, hard_iface->net_dev->mtu,
-                           ETH_DATA_LEN + BATADV_HEADER_LEN);
+                           ETH_DATA_LEN + max_header_len);
 
        if (!atomic_read(&bat_priv->fragmentation) &&
-           hard_iface->net_dev->mtu < ETH_DATA_LEN + BATADV_HEADER_LEN)
+           hard_iface->net_dev->mtu < ETH_DATA_LEN + max_header_len)
                batadv_info(hard_iface->soft_iface,
-                           "The MTU of interface %s is too small (%i) to handle the transport of batman-adv packets. If you experience problems getting traffic through try increasing the MTU to %zi.\n",
+                           "The MTU of interface %s is too small (%i) to handle the transport of batman-adv packets. If you experience problems getting traffic through try increasing the MTU to %i.\n",
                            hard_iface->net_dev->name, hard_iface->net_dev->mtu,
-                           ETH_DATA_LEN + BATADV_HEADER_LEN);
+                           ETH_DATA_LEN + max_header_len);
 
        if (batadv_hardif_is_iface_up(hard_iface))
                batadv_hardif_activate_interface(hard_iface);

diff --git a/net/batman-adv/main.c b/net/batman-adv/main.c
index 519138e32fe6157ab214e5568b1e01cec14a6942..7f3a5c426615788b4565dcd86bf06c2e34e7627e 100644 (file)
--- a/net/batman-adv/main.c
+++ b/net/batman-adv/main.c
@@ -255,6 +255,31 @@ out:
        return primary_if;
 }
 
+/**
+ * batadv_max_header_len - calculate maximum encapsulation overhead for a
+ *  payload packet
+ *
+ * Return the maximum encapsulation overhead in bytes.
+ */
+int batadv_max_header_len(void)
+{
+       int header_len = 0;
+
+       header_len = max_t(int, header_len,
+                          sizeof(struct batadv_unicast_packet));
+       header_len = max_t(int, header_len,
+                          sizeof(struct batadv_unicast_4addr_packet));
+       header_len = max_t(int, header_len,
+                          sizeof(struct batadv_bcast_packet));
+
+#ifdef CONFIG_BATMAN_ADV_NC
+       header_len = max_t(int, header_len,
+                          sizeof(struct batadv_coded_packet));
+#endif
+
+       return header_len;
+}
+
 /**
  * batadv_skb_set_priority - sets skb priority according to packet content
  * @skb: the packet to be sent

diff --git a/net/batman-adv/main.h b/net/batman-adv/main.h
index 6a74a42253263d92c01fba35b4a9321ece74a43e..54c13d51edbeee58dcf04e2e03fa718d8cd06555 100644 (file)
--- a/net/batman-adv/main.h
+++ b/net/batman-adv/main.h
@@ -191,6 +191,7 @@ void batadv_mesh_free(struct net_device *soft_iface);
 int batadv_is_my_mac(struct batadv_priv *bat_priv, const uint8_t *addr);
 struct batadv_hard_iface *
 batadv_seq_print_text_primary_if_get(struct seq_file *seq);
+int batadv_max_header_len(void);
 void batadv_skb_set_priority(struct sk_buff *skb, int offset);
 int batadv_batman_skb_recv(struct sk_buff *skb, struct net_device *dev,
                           struct packet_type *ptype,

diff --git a/net/batman-adv/soft-interface.c b/net/batman-adv/soft-interface.c
index 87e7e4ed216d6820d452594e42b02dfd6e43db71..15c7237f427b6ae31abb27f1670826cc3ca2d0b9 100644 (file)
--- a/net/batman-adv/soft-interface.c
+++ b/net/batman-adv/soft-interface.c
@@ -626,7 +626,7 @@ static void batadv_softif_init_early(struct net_device *dev)
         */
        dev->mtu = ETH_DATA_LEN;
        /* reserve more space in the skbuff for our header */
-       dev->hard_header_len = BATADV_HEADER_LEN;
+       dev->hard_header_len = batadv_max_header_len();
 
        /* generate random address */
        eth_hw_addr_random(dev);

diff --git a/net/batman-adv/types.h b/net/batman-adv/types.h
index d517d5dde6adfdbe2dba226f4b6ff5be7e8e8e13..5cbb0d09a9b58519dfc17bd59f857710622e2d95 100644 (file)
--- a/net/batman-adv/types.h
+++ b/net/batman-adv/types.h
@@ -24,13 +24,6 @@
 #include "bitarray.h"
 #include <linux/kernel.h>
 
-/**
- * Maximum overhead for the encapsulation for a payload packet
- */
-#define BATADV_HEADER_LEN \
-       (ETH_HLEN + max(sizeof(struct batadv_unicast_packet), \
-                       sizeof(struct batadv_bcast_packet)))
-
 #ifdef CONFIG_BATMAN_ADV_DAT
 
 /* batadv_dat_addr_t is the type used for all DHT addresses. If it is changed,