From: Sven Eckelmann Date: Thu, 26 Nov 2020 12:52:46 +0000 (+0100) Subject: vxlan: Add needed_headroom for lower device X-Git-Tag: v4.14.213~197 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=951481c52a94ba646e35b99fdb93177ab580555b;p=thirdparty%2Fkernel%2Fstable.git vxlan: Add needed_headroom for lower device [ Upstream commit 0a35dc41fea67ac4495ce7584406bf9557a6e7d0 ] 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 Signed-off-by: Sven Eckelmann Tested-by: Annika Wickert Link: https://lore.kernel.org/r/20201126125247.1047977-1-sven@narfation.org Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- diff --git a/drivers/net/vxlan.c b/drivers/net/vxlan.c index 82efa5bbf568b..c21f28840f05b 100644 --- a/drivers/net/vxlan.c +++ b/drivers/net/vxlan.c @@ -3184,6 +3184,7 @@ 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);