The maximum of hard_header_len and maximum of all needed_(head|tail)room of all slave interfaces of a batman-adv device must be used to define the batman-adv device needed_(head|tail)room. This is required to avoid too small buffer problems when these slave devices try to send the encapsulated packet in a tx path without the possibility to resize the skbuff.

Signed-off-by: Sven Eckelmann sven@narfation.org --- v4: - only check non-BATADV_IF_NOT_IN_USE interfaces - drop the batadv_hardif_disable_interface changes which are already handled by the non-BATADV_IF_NOT_IN_USE check v3: - set hard_header_len always to ETH_HLEN and only modify needed_headroom as done in mac80211/vxlan - do the same for needed_tailroom v2: - based on patch "batman-adv: don't access unregistered net_device object" - remove the function call from batadv_update_min_mtu - instead use batadv_hardif_disable_interface + batadv_hardif_enable_interface --- net/batman-adv/hard-interface.c | 41 +++++++++++++++++++++++++++++++++++++++++ net/batman-adv/soft-interface.c | 2 -- 2 files changed, 41 insertions(+), 2 deletions(-)

diff --git a/net/batman-adv/hard-interface.c b/net/batman-adv/hard-interface.c index 0565b20bfa6d..f11345e163d7 100644 --- a/net/batman-adv/hard-interface.c +++ b/net/batman-adv/hard-interface.c @@ -252,6 +252,44 @@ static void batadv_check_known_mac_addr(const struct net_device *net_dev) rcu_read_unlock(); }

+/** + * batadv_hardif_recalc_extra_skbroom() - Recalculate skbuff extra head/tailroom + * @soft_iface: netdev struct of the mesh interface + */ +static void batadv_hardif_recalc_extra_skbroom(struct net_device *soft_iface) +{ + const struct batadv_hard_iface *hard_iface; + unsigned short lower_header_len = ETH_HLEN; + unsigned short lower_headroom = 0; + unsigned short lower_tailroom = 0; + unsigned short needed_headroom; + + rcu_read_lock(); + list_for_each_entry_rcu(hard_iface, &batadv_hardif_list, list) { + if (hard_iface->if_status == BATADV_IF_NOT_IN_USE) + continue; + + if (hard_iface->soft_iface != soft_iface) + continue; + + lower_header_len = max_t(unsigned short, lower_header_len, + hard_iface->net_dev->hard_header_len); + + lower_headroom = max_t(unsigned short, lower_headroom, + hard_iface->net_dev->needed_headroom); + + lower_tailroom = max_t(unsigned short, lower_tailroom, + hard_iface->net_dev->needed_tailroom); + } + rcu_read_unlock(); + + needed_headroom = lower_headroom + (lower_header_len - ETH_HLEN); + needed_headroom += batadv_max_header_len(); + + soft_iface->needed_headroom = needed_headroom; + soft_iface->needed_tailroom = lower_tailroom; +} + int batadv_hardif_min_mtu(struct net_device *soft_iface) { struct batadv_priv *bat_priv = netdev_priv(soft_iface); @@ -474,6 +512,8 @@ int batadv_hardif_enable_interface(struct batadv_hard_iface *hard_iface, "Not using interface %s (retrying later): interface not active\n", hard_iface->net_dev->name);

+ batadv_hardif_recalc_extra_skbroom(soft_iface); + /* begin scheduling originator messages on that interface */ batadv_schedule_bat_ogm(hard_iface);

@@ -529,6 +569,7 @@ void batadv_hardif_disable_interface(struct batadv_hard_iface *hard_iface, dev_put(hard_iface->soft_iface);

netdev_upper_dev_unlink(hard_iface->net_dev, hard_iface->soft_iface); + batadv_hardif_recalc_extra_skbroom(hard_iface->soft_iface);

/* nobody uses this interface anymore */ if (!bat_priv->num_ifaces) { diff --git a/net/batman-adv/soft-interface.c b/net/batman-adv/soft-interface.c index 36b23f31df2a..cce8e896d511 100644 --- a/net/batman-adv/soft-interface.c +++ b/net/batman-adv/soft-interface.c @@ -947,8 +947,6 @@ static void batadv_softif_init_early(struct net_device *dev) * have not been initialized yet */ dev->mtu = ETH_DATA_LEN; - /* reserve more space in the skbuff for our header */ - dev->hard_header_len = batadv_max_header_len();

/* generate random address */ eth_hw_addr_random(dev);