From 0a35dc41fea67ac4495ce7584406bf9557a6e7d0 Mon Sep 17 00:00:00 2001 From: Sven Eckelmann <sven@narfation.org> Date: Thu, 26 Nov 2020 13:52:46 +0100 Subject: [PATCH] vxlan: Add needed_headroom for lower device 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> Tested-by: Annika Wickert <aw@awlnx.space> Link: https://lore.kernel.org/r/20201126125247.1047977-1-sven@narfation.org Signed-off-by: Jakub Kicinski <kuba@kernel.org> --- drivers/net/vxlan.c | 1 + 1 file changed, 1 insertion(+) diff --git a/drivers/net/vxlan.c b/drivers/net/vxlan.c index 1a557aeba32b4e..55fa3fbb80f179 100644 --- a/drivers/net/vxlan.c +++ b/drivers/net/vxlan.c @@ -3798,6 +3798,7 @@ 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); -- GitLab