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batman-adv: Check hardif MTU against runtime MTU

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If the MTU of the soft/mesh interface was already reduced (enough), it is
not necessary to print a warning about a hard interface not having a MTU to
transport ethernet payloads of 1500 bytes.

Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>
This commit is contained in:
Sven Eckelmann 2023-07-27 10:13:43 +02:00 committed by Simon Wunderlich
parent e4b8178045
commit 112cbcb4af
1 changed files with 13 additions and 7 deletions
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20
net/batman-adv/hard-interface.c
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@ -9,6 +9,7 @@
#include <linux/atomic.h>
#include <linux/byteorder/generic.h>
#include <linux/compiler.h>
#include <linux/container_of.h>
#include <linux/errno.h>
#include <linux/gfp.h>
@ -699,9 +700,14 @@ int batadv_hardif_enable_interface(struct batadv_hard_iface *hard_iface,
struct batadv_priv *bat_priv;
__be16 ethertype = htons(ETH_P_BATMAN);
int max_header_len = batadv_max_header_len();
unsigned int required_mtu;
unsigned int hardif_mtu;
int ret;
if (hard_iface->net_dev->mtu < ETH_MIN_MTU + max_header_len)
hardif_mtu = READ_ONCE(hard_iface->net_dev->mtu);
required_mtu = READ_ONCE(soft_iface->mtu) + max_header_len;
if (hardif_mtu < ETH_MIN_MTU + max_header_len)
return -EINVAL;
if (hard_iface->if_status != BATADV_IF_NOT_IN_USE)
@ -734,18 +740,18 @@ int batadv_hardif_enable_interface(struct batadv_hard_iface *hard_iface,
hard_iface->net_dev->name);
if (atomic_read(&bat_priv->fragmentation) &&
hard_iface->net_dev->mtu < ETH_DATA_LEN + max_header_len)
hardif_mtu < required_mtu)
batadv_info(hard_iface->soft_iface,
"The MTU of interface %s is too small (%i) to handle the transport of batman-adv packets. Packets going over this interface will be fragmented on layer2 which could impact the performance. Setting the MTU to %i would solve the problem.\n",
hard_iface->net_dev->name, hard_iface->net_dev->mtu,
ETH_DATA_LEN + max_header_len);
hard_iface->net_dev->name, hardif_mtu,
required_mtu);
if (!atomic_read(&bat_priv->fragmentation) &&
hard_iface->net_dev->mtu < ETH_DATA_LEN + max_header_len)
hardif_mtu < required_mtu)
batadv_info(hard_iface->soft_iface,
"The MTU of interface %s is too small (%i) to handle the transport of batman-adv packets. If you experience problems getting traffic through try increasing the MTU to %i.\n",
hard_iface->net_dev->name, hard_iface->net_dev->mtu,
ETH_DATA_LEN + max_header_len);
hard_iface->net_dev->name, hardif_mtu,
required_mtu);
if (batadv_hardif_is_iface_up(hard_iface))
batadv_hardif_activate_interface(hard_iface);