From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Russell Senior , Antonio Quartulli , Marek Lindner Subject: [PATCH 3.13 063/172] batman-adv: fix soft-interface MTU computation Date: Tue, 4 Mar 2014 12:02:27 -0800 Message-Id: <20140304200301.757288975@linuxfoundation.org> In-Reply-To: <20140304200259.626667112@linuxfoundation.org> References: <20140304200259.626667112@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: 3.13-stable review patch. If anyone has any objections, please let me know. ------------------ From: Antonio Quartulli [ Upstream commit 930cd6e46eadce8b8ed2a232ee536e5fd286c152 ] 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 a19d3d85e1b854e4a483a55d740a42458085560d ("batman-adv: limit local translation table max size") Reported-by: Russell Senior Signed-off-by: Antonio Quartulli Signed-off-by: Marek Lindner Signed-off-by: Greg Kroah-Hartman --- net/batman-adv/hard-interface.c | 22 ++++++++++++++-------- 1 file changed, 14 insertions(+), 8 deletions(-) --- a/net/batman-adv/hard-interface.c +++ b/net/batman-adv/hard-interface.c @@ -244,7 +244,7 @@ int batadv_hardif_min_mtu(struct net_dev { 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_dev } 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_dev 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. */