l2: fix vxlan src port entropy with mpls payload

l2 tunnels like vxlan, gtpu, geneva use vnet_l2_compute_flow_hash() to
compute flow hash for udp src port entropy. In case of inner mpls tunnels
to the same lsr ethernet src and dst macs are the same, so l2 flow hash
is also the same leading to no src port entropy and the only rss queue
overflow on receiver side.

Fix it for all the possible vnet_l2_compute_flow_hash callers by making
mpls playload hash in additon to ip4/ip6. Visible performance impact is
not expected as it's only one check for mpls ethertype for common cases.

Type: fix
Signed-off-by: Vladislav Grishenko <themiron@yandex-team.ru>
Change-Id: I69153d42fb3d7c094a670c674fac8d14039c626a

1 files changed, 5 insertions, 1 deletions

diff --git a/src/vnet/l2/l2_input.h b/src/vnet/l2/l2_input.h
index 7d1dc9c1d05..3de1537b45e 100644
--- a/src/vnet/l2/l2_input.h
+++ b/src/vnet/l2/l2_input.h
@@ -27,6 +27,7 @@
 #include <vnet/ethernet/packet.h>
 #include <vnet/ip/ip4_inlines.h>
 #include <vnet/ip/ip6_inlines.h>
+#include <vnet/mpls/mpls_lookup.h>
 
 /* l2 connection type */
 typedef enum l2_input_flags_t_
@@ -327,7 +328,7 @@ vnet_update_l2_len (vlib_buffer_t *b)
 
 /*
  * Compute flow hash of an ethernet packet, use 5-tuple hash if L3 packet
- * is ip4 or ip6. Otherwise hash on smac/dmac/etype.
+ * is ip4, ip6, or mpls. Otherwise hash on smac/dmac/etype.
  * The vlib buffer current pointer is expected to be at ethernet header
  * and vnet l2.l2_len is expected to be setup already.
  */
@@ -342,6 +343,9 @@ vnet_l2_compute_flow_hash (vlib_buffer_t * b)
     return ip4_compute_flow_hash ((ip4_header_t *) l3h, IP_FLOW_HASH_DEFAULT);
   else if (ethertype == ETHERNET_TYPE_IP6)
     return ip6_compute_flow_hash ((ip6_header_t *) l3h, IP_FLOW_HASH_DEFAULT);
+  else if (ethertype == ETHERNET_TYPE_MPLS)
+    return mpls_compute_flow_hash ((mpls_unicast_header_t *) l3h,
+				   IP_FLOW_HASH_DEFAULT);
   else
     {
       u32 a, b, c;