While vxlan doesn't need any extra tailroom, the lowerdev might need it. In
that case, copy it over to reduce the chance for additional (re)allocations
in the transmit path.
Signed-off-by: Sven Eckelmann <sven@narfation.org>
Link: https://lore.kernel.org/r/20201126125247.1047977-2-sven@narfation.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
 
                needed_headroom = lowerdev->hard_header_len;
                needed_headroom += lowerdev->needed_headroom;
 
+               dev->needed_tailroom = lowerdev->needed_tailroom;
+
                max_mtu = lowerdev->mtu - (use_ipv6 ? VXLAN6_HEADROOM :
                                           VXLAN_HEADROOM);
                if (max_mtu < ETH_MIN_MTU)