From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Antonio Quartulli Date: Tue, 21 Jan 2014 11:22:05 +0100 Message-Id: <1390299725-1873-1-git-send-email-antonio@meshcoding.com> Subject: [B.A.T.M.A.N.] [PATCH maint] batman-adv: fix soft-interface MTU computation Reply-To: The list for a Better Approach To Mobile Ad-hoc Networking List-Id: The list for a Better Approach To Mobile Ad-hoc Networking List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: b.a.t.m.a.n@lists.open-mesh.org Cc: Antonio Quartulli 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. Signed-off-by: Antonio Quartulli --- This patch is missing a Reported-by clause because I did not have "russell"'s email address at hand. Will be added later before being merged. Cheers, 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. */ -- 1.8.5.3