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

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

net/batman-adv/hard-interface.c

+14 −8
Original line number Original line Diff line number Diff line
@@ -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) 
	}

	}

	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) 
	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. */