It was observed that sending data via batadv over vxlan (on top of wireguard) reduced the performance massively compared to raw ethernet or batadv on raw ethernet. A check of perf data showed that the vxlan_build_skb was calling all the time pskb_expand_head to allocate enough headroom for:

min_headroom = LL_RESERVED_SPACE(dst->dev) + dst->header_len + VXLAN_HLEN + iphdr_len;

But the vxlan_config_apply only requested needed headroom for:

lowerdev->hard_header_len + VXLAN6_HEADROOM or VXLAN_HEADROOM

So it completely ignored the needed_headroom of the lower device. The first caller of net_dev_xmit could therefore never make sure that enough headroom was allocated for the rest of the transmit path.

Cc: Annika Wickert annika.wickert@exaring.de Signed-off-by: Sven Eckelmann sven@narfation.org --- drivers/net/vxlan.c | 1 + 1 file changed, 1 insertion(+)

diff --git a/drivers/net/vxlan.c b/drivers/net/vxlan.c index 236fcc55a5fd..25b5b5a2dfea 100644 --- a/drivers/net/vxlan.c +++ b/drivers/net/vxlan.c @@ -3799,6 +3799,7 @@ static void vxlan_config_apply(struct net_device *dev, dev->gso_max_segs = lowerdev->gso_max_segs;

needed_headroom = lowerdev->hard_header_len; + needed_headroom += lowerdev->needed_headroom;

max_mtu = lowerdev->mtu - (use_ipv6 ? VXLAN6_HEADROOM : VXLAN_HEADROOM);