Repository : ssh://git@diktynna/batman-adv On branches: main,main

commit 533f83ba636d6b8084427c8e56664c09a3cf9d60 Author: Sven Eckelmann sven@narfation.org Date: Sun Feb 2 17:04:14 2025 +0100

batman-adv: Limit aggregation size to outgoing MTU

If a B.A.T.M.A.N. IV aggregated OGM was prepared, it was always assumed that 512 bytes (BATADV_MAX_AGGREGATION_BYTES) can be transmitted. But the outgoing MTU might be too small for these 512 bytes and the aggregation size must be adjusted in this case. Otherwise, the aggregates will cause unnecessary packet loss.

For now, the non-aggregated packet length is not touched.

Signed-off-by: Sven Eckelmann sven@narfation.org

533f83ba636d6b8084427c8e56664c09a3cf9d60 net/batman-adv/bat_iv_ogm.c | 16 ++++++++++------ 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/net/batman-adv/bat_iv_ogm.c b/net/batman-adv/bat_iv_ogm.c index f5ddcedc..d96285b5 100644 --- a/net/batman-adv/bat_iv_ogm.c +++ b/net/batman-adv/bat_iv_ogm.c @@ -443,22 +443,26 @@ batadv_iv_ogm_can_aggregate(const struct batadv_ogm_packet *new_bat_ogm_packet, const struct batadv_forw_packet *forw_packet) { struct batadv_ogm_packet *batadv_ogm_packet; - int aggregated_bytes = forw_packet->packet_len + packet_len; + unsigned int aggregated_bytes = forw_packet->packet_len + packet_len; struct batadv_hard_iface *primary_if = NULL; u8 packet_num = forw_packet->num_packets; bool res = false; unsigned long aggregation_end_time; + unsigned int max_bytes;

batadv_ogm_packet = (struct batadv_ogm_packet *)forw_packet->skb->data; aggregation_end_time = send_time; aggregation_end_time += msecs_to_jiffies(BATADV_MAX_AGGREGATION_MS);

+ max_bytes = min_t(unsigned int, if_outgoing->net_dev->mtu, + BATADV_MAX_AGGREGATION_BYTES); + /* we can aggregate the current packet to this aggregated packet * if: * * - the send time is within our MAX_AGGREGATION_MS time * - the resulting packet won't be bigger than - * MAX_AGGREGATION_BYTES + * MAX_AGGREGATION_BYTES and MTU of the outgoing interface * - the number of packets is lower than MAX_AGGREGATION_PACKETS * otherwise aggregation is not possible */ @@ -466,7 +470,7 @@ batadv_iv_ogm_can_aggregate(const struct batadv_ogm_packet *new_bat_ogm_packet, !time_after_eq(aggregation_end_time, forw_packet->send_time)) return false;

- if (aggregated_bytes > BATADV_MAX_AGGREGATION_BYTES) + if (aggregated_bytes > max_bytes) return false;

if (packet_num >= BATADV_MAX_AGGREGATION_PACKETS) @@ -551,9 +555,9 @@ static void batadv_iv_ogm_aggregate_new(const unsigned char *packet_buff, unsigned int skb_size; atomic_t *queue_left = own_packet ? NULL : &bat_priv->batman_queue_left;

- if (atomic_read(&bat_priv->aggregated_ogms) && - packet_len < BATADV_MAX_AGGREGATION_BYTES) - skb_size = BATADV_MAX_AGGREGATION_BYTES; + if (atomic_read(&bat_priv->aggregated_ogms)) + skb_size = max_t(unsigned int, BATADV_MAX_AGGREGATION_BYTES, + packet_len); else skb_size = packet_len;