Repository : ssh://git@open-mesh.org/batman-adv
On branch : maint
commit 2b108ccd0533e1375e44c73ec58c69dde9a71687 Author: Antonio Quartulli antonio@meshcoding.com Date: Tue Jan 21 11:22:05 2014 +0100
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 f7f2fe494388fca828094a4ebdab918a7b2d64f8 ("batman-adv: limit local translation table max size")
Reported-by: Russell Senior russell@personaltelco.net Signed-off-by: Antonio Quartulli antonio@meshcoding.com Signed-off-by: Marek Lindner mareklindner@neomailbox.ch
2b108ccd0533e1375e44c73ec58c69dde9a71687 hard-interface.c | 22 ++++++++++++++-------- 1 file changed, 14 insertions(+), 8 deletions(-)
diff --git a/hard-interface.c b/hard-interface.c index 6792e03..0eb0b3b 100644 --- a/hard-interface.c +++ b/hard-interface.c @@ -244,7 +244,7 @@ int batadv_hardif_min_mtu(struct net_device *soft_iface) { struct batadv_priv *bat_priv = netdev_priv(soft_iface); const struct batadv_hard_iface *hard_iface; - int min_mtu = ETH_DATA_LEN; + int min_mtu = INT_MAX;
rcu_read_lock(); list_for_each_entry_rcu(hard_iface, &batadv_hardif_list, list) { @@ -259,8 +259,6 @@ int batadv_hardif_min_mtu(struct net_device *soft_iface) } rcu_read_unlock();
- atomic_set(&bat_priv->packet_size_max, min_mtu); - if (atomic_read(&bat_priv->fragmentation) == 0) goto out;
@@ -271,13 +269,21 @@ int batadv_hardif_min_mtu(struct net_device *soft_iface) min_mtu = min_t(int, min_mtu, BATADV_FRAG_MAX_FRAG_SIZE); min_mtu -= 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 - 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. */