batman-adv/patches/0003-batman-adv-fix-soft-interface-MTU-computation.patch

   1 From 2b108ccd0533e1375e44c73ec58c69dde9a71687 Mon Sep 17 00:00:00 2001
   2 From: Antonio Quartulli <antonio@meshcoding.com>
   3 Date: Tue, 21 Jan 2014 11:22:05 +0100
   4 Subject: [PATCH 3/5] batman-adv: fix soft-interface MTU computation
   5
   6 The current MTU computation always returns a value
   7 smaller than 1500bytes even if the real interfaces
   8 have an MTU large enough to compensate the batman-adv
   9 overhead.
  10
  11 Fix the computation by properly returning the highest
  12 admitted value.
  13
  14 Introduced by f7f2fe494388fca828094a4ebdab918a7b2d64f8
  15 ("batman-adv: limit local translation table max size")
  16
  17 Reported-by: Russell Senior <russell@personaltelco.net>
  18 Signed-off-by: Antonio Quartulli <antonio@meshcoding.com>
  19 Signed-off-by: Marek Lindner <mareklindner@neomailbox.ch>
  20 ---
  21  hard-interface.c | 22 ++++++++++++++--------
  22  1 file changed, 14 insertions(+), 8 deletions(-)
  23
  24 diff --git a/hard-interface.c b/hard-interface.c
  25 index 6792e03..0eb0b3b 100644
  26 --- a/hard-interface.c
  27 +++ b/hard-interface.c
  28 @@ -244,7 +244,7 @@ int batadv_hardif_min_mtu(struct net_device *soft_iface)
  29  {
  30         struct batadv_priv *bat_priv = netdev_priv(soft_iface);
  31         const struct batadv_hard_iface *hard_iface;
  32 -       int min_mtu = ETH_DATA_LEN;
  33 +       int min_mtu = INT_MAX;
  34
  35         rcu_read_lock();
  36         list_for_each_entry_rcu(hard_iface, &batadv_hardif_list, list) {
  37 @@ -259,8 +259,6 @@ int batadv_hardif_min_mtu(struct net_device *soft_iface)
  38         }
  39         rcu_read_unlock();
  40
  41 -       atomic_set(&bat_priv->packet_size_max, min_mtu);
  42 -
  43         if (atomic_read(&bat_priv->fragmentation) == 0)
  44                 goto out;
  45
  46 @@ -271,13 +269,21 @@ int batadv_hardif_min_mtu(struct net_device *soft_iface)
  47         min_mtu = min_t(int, min_mtu, BATADV_FRAG_MAX_FRAG_SIZE);
  48         min_mtu -= sizeof(struct batadv_frag_packet);
  49         min_mtu *= BATADV_FRAG_MAX_FRAGMENTS;
  50 -       atomic_set(&bat_priv->packet_size_max, min_mtu);
  51 -
  52 -       /* with fragmentation enabled we can fragment external packets easily */
  53 -       min_mtu = min_t(int, min_mtu, ETH_DATA_LEN);
  54
  55  out:
  56 -       return min_mtu - batadv_max_header_len();
  57 +       /* report to the other components the maximum amount of bytes that
  58 +        * batman-adv can send over the wire (without considering the payload
  59 +        * overhead). For example, this value is used by TT to compute the
  60 +        * maximum local table table size
  61 +        */
  62 +       atomic_set(&bat_priv->packet_size_max, min_mtu);
  63 +
  64 +       /* the real soft-interface MTU is computed by removing the payload
  65 +        * overhead from the maximum amount of bytes that was just computed.
  66 +        *
  67 +        * However batman-adv does not support MTUs bigger than ETH_DATA_LEN
  68 +        */
  69 +       return min_t(int, min_mtu - batadv_max_header_len(), ETH_DATA_LEN);
  70  }
  71
  72  /* adjusts the MTU if a new interface with a smaller MTU appeared. */
  73 --
  74 1.8.5.3
  75