From: Sven Eckelmann sven@narfation.org
[ 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 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 Signed-off-by: Sasha Levin sashal@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 630ac00a34ede..3753cf0942865 100644 --- a/drivers/net/vxlan.c +++ b/drivers/net/vxlan.c @@ -3538,6 +3538,7 @@ 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);