Commit 112cbcb4 authored by Sven Eckelmann's avatar Sven Eckelmann Committed by Simon Wunderlich
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batman-adv: Check hardif MTU against runtime MTU 



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: default avatarSven Eckelmann <sven@narfation.org>
Signed-off-by: default avatarSimon Wunderlich <sw@simonwunderlich.de>
parent e4b81780

net/batman-adv/hard-interface.c

+13 −7
Original line number Diff line number Diff line
@@ -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);