Commit 930cd6e4 authored by Antonio Quartulli's avatar Antonio Quartulli

batman-adv: fix soft-interface MTU computation

The current MTU computation always returns a value
smaller than 1500bytes even if the real interfaces
have an MTU large enough to compensate the batman-adv
overhead.

Fix the computation by properly returning the highest
admitted value.

Introduced by a19d3d85
("batman-adv: limit local translation table max size")
Reported-by: default avatarRussell Senior <russell@personaltelco.net>
Signed-off-by: default avatarAntonio Quartulli <antonio@meshcoding.com>
Signed-off-by: default avatarMarek Lindner <mareklindner@neomailbox.ch>
parent 0fd5d57b
...@@ -241,7 +241,7 @@ int batadv_hardif_min_mtu(struct net_device *soft_iface) ...@@ -241,7 +241,7 @@ int batadv_hardif_min_mtu(struct net_device *soft_iface)
{ {
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; const struct batadv_hard_iface *hard_iface;
int min_mtu = ETH_DATA_LEN; int min_mtu = INT_MAX;
rcu_read_lock(); rcu_read_lock();
list_for_each_entry_rcu(hard_iface, &batadv_hardif_list, list) { list_for_each_entry_rcu(hard_iface, &batadv_hardif_list, list) {
...@@ -256,8 +256,6 @@ int batadv_hardif_min_mtu(struct net_device *soft_iface) ...@@ -256,8 +256,6 @@ int batadv_hardif_min_mtu(struct net_device *soft_iface)
} }
rcu_read_unlock(); rcu_read_unlock();
atomic_set(&bat_priv->packet_size_max, min_mtu);
if (atomic_read(&bat_priv->fragmentation) == 0) if (atomic_read(&bat_priv->fragmentation) == 0)
goto out; goto out;
...@@ -268,13 +266,21 @@ int batadv_hardif_min_mtu(struct net_device *soft_iface) ...@@ -268,13 +266,21 @@ int batadv_hardif_min_mtu(struct net_device *soft_iface)
min_mtu = min_t(int, min_mtu, BATADV_FRAG_MAX_FRAG_SIZE); min_mtu = min_t(int, min_mtu, BATADV_FRAG_MAX_FRAG_SIZE);
min_mtu -= sizeof(struct batadv_frag_packet); min_mtu -= sizeof(struct batadv_frag_packet);
min_mtu *= BATADV_FRAG_MAX_FRAGMENTS; 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: out:
return min_mtu - batadv_max_header_len(); /* report to the other components the maximum amount of bytes that
* batman-adv can send over the wire (without considering the payload
* overhead). For example, this value is used by TT to compute the
* maximum local table table size
*/
atomic_set(&bat_priv->packet_size_max, min_mtu);
/* the real soft-interface MTU is computed by removing the payload
* overhead from the maximum amount of bytes that was just computed.
*
* However batman-adv does not support MTUs bigger than ETH_DATA_LEN
*/
return min_t(int, min_mtu - batadv_max_header_len(), ETH_DATA_LEN);
} }
/* adjusts the MTU if a new interface with a smaller MTU appeared. */ /* adjusts the MTU if a new interface with a smaller MTU appeared. */
......
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