vxlan: Fix error that was resulting in VXLAN MTU size being 10 bytes too large

This change fixes an issue I found where VXLAN frames were fragmented when
they were up to the VXLAN MTU size.  I root caused the issue to the fact that
the headroom was 4 + 20 + 8 + 8.  This math doesn't appear to be correct
because we are not inserting a VLAN header, but instead a 2nd Ethernet header.
As such the math for the overhead should be 20 + 8 + 8 + 14 to account for the
extra headers that are inserted for VXLAN.

Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/vxlan.c b/drivers/net/vxlan.c
index 7b4adde93c016b7e020306220e372524da9f5deb..0c4d0f49ab462e15a2243800b14e95abca8659e9 100644 (file)
--- a/drivers/net/vxlan.c
+++ b/drivers/net/vxlan.c
@@ -50,8 +50,8 @@
 
 #define VXLAN_N_VID    (1u << 24)
 #define VXLAN_VID_MASK (VXLAN_N_VID - 1)
-/* VLAN + IP header + UDP + VXLAN */
-#define VXLAN_HEADROOM (4 + 20 + 8 + 8)
+/* IP header + UDP + VXLAN + Ethernet header */
+#define VXLAN_HEADROOM (20 + 8 + 8 + 14)
 
 #define VXLAN_FLAGS 0x08000000 /* struct vxlanhdr.vx_flags required value. */