devices: fix af_packet GSO check

Type: fix

This fixes the GSO size calculation in af_packet
which didn't include the ethernet size.
This is not ideal, as we default to the host
side mtu to check whether a packet is GSO or not
and to set the GSO size. But there doesn't seem
to be more info passed with the packets.

Change-Id: I9769e1dd21d5989b4cf67295352b5535454f88d1
Signed-off-by: Nathan Skrzypczak <nathan.skrzypczak@gmail.com>

diff --git a/src/vnet/devices/af_packet/node.c b/src/vnet/devices/af_packet/node.c
index 0fdae5c..efe7016 100644 (file)
--- a/src/vnet/devices/af_packet/node.c
+++ b/src/vnet/devices/af_packet/node.c
@@ -209,6 +209,7 @@ af_packet_device_input_fn (vlib_main_t * vm, vlib_node_runtime_t * node,
   u32 thread_index = vm->thread_index;
   u32 n_buffer_bytes = vlib_buffer_get_default_data_size (vm);
   u32 min_bufs = apif->rx_req->tp_frame_size / n_buffer_bytes;
+  u32 eth_header_size = 0;
   vlib_buffer_t bt;
 
   if (apif->mode == AF_PACKET_IF_MODE_IP)
@@ -217,6 +218,7 @@ af_packet_device_input_fn (vlib_main_t * vm, vlib_node_runtime_t * node,
     }
   else
     {
+      eth_header_size = sizeof (ethernet_header_t);
       next_index = VNET_DEVICE_INPUT_NEXT_ETHERNET_INPUT;
       if (PREDICT_FALSE (apif->per_interface_next_index != ~0))
        next_index = apif->per_interface_next_index;
@@ -307,7 +309,10 @@ af_packet_device_input_fn (vlib_main_t * vm, vlib_node_runtime_t * node,
                  first_b0 = vlib_get_buffer (vm, first_bi0);
                  if (tph->tp_status & TP_STATUS_CSUMNOTREADY)
                    mark_tcp_udp_cksum_calc (first_b0, &l4_hdr_sz);
-                 if (tph->tp_snaplen > apif->host_mtu)
+                 /* This is a trade-off for GSO. As kernel isn't passing
+                  * us the GSO state or size, we guess it by comparing it
+                  * to the host MTU of the interface */
+                 if (tph->tp_snaplen > (apif->host_mtu + eth_header_size))
                    fill_gso_buffer_flags (first_b0, apif->host_mtu,
                                           l4_hdr_sz);
                }