gso: fix the gso segmentation

Type: fix

This fix is backported from master partial of patch:
gso: add vxlan tunnel support

It fixes required number of buffers for segmentation and
also enables gso infra node on sub-interfaces.

Change-Id: I2cf93cdb39c67e2252a3549905d141fffa95d249
Signed-off-by: Mohsin Kazmi <sykazmi@cisco.com>

3 files changed, 39 insertions, 29 deletions

diff --git a/src/vnet/gso/gso.c b/src/vnet/gso/gso.c
index cf90d22696d..231196adc5d 100644
--- a/src/vnet/gso/gso.c
+++ b/src/vnet/gso/gso.c
@@ -34,9 +34,11 @@ vnet_sw_interface_gso_enable_disable (u32 sw_if_index, u8 enable)
   em = &ethernet_main;
   si = vnet_get_sw_interface (vnm, sw_if_index);
 
-  /*
-   * only ethernet HW interfaces are supported at this time
-   */
+  if (si->type == VNET_SW_INTERFACE_TYPE_SUB)
+    {
+      si = vnet_get_sup_sw_interface (vnm, sw_if_index);
+    }
+
   if (si->type != VNET_SW_INTERFACE_TYPE_HARDWARE)
     {
       return (VNET_API_ERROR_INVALID_VALUE);
diff --git a/src/vnet/gso/gso.h b/src/vnet/gso/gso.h
index 79869c2644b..27d4bc765a9 100644
--- a/src/vnet/gso/gso.h
+++ b/src/vnet/gso/gso.h
@@ -51,20 +51,6 @@ vnet_gso_header_offset_parser (vlib_buffer_t * b0, int is_ip6)
   u8 l4_proto = 0;
   u8 l4_hdr_sz = 0;
 
-  if (PREDICT_TRUE ((b0->flags & (VNET_BUFFER_F_L2_HDR_OFFSET_VALID |
-				  VNET_BUFFER_F_L3_HDR_OFFSET_VALID |
-				  VNET_BUFFER_F_L4_HDR_OFFSET_VALID)) ==
-		    (VNET_BUFFER_F_L2_HDR_OFFSET_VALID |
-		     VNET_BUFFER_F_L3_HDR_OFFSET_VALID |
-		     VNET_BUFFER_F_L4_HDR_OFFSET_VALID)))
-    {
-      gho.l2_hdr_offset = vnet_buffer (b0)->l2_hdr_offset;
-      gho.l3_hdr_offset = vnet_buffer (b0)->l3_hdr_offset;
-      gho.l4_hdr_offset = vnet_buffer (b0)->l4_hdr_offset;
-      gho.l4_hdr_sz = vnet_buffer2 (b0)->gso_l4_hdr_sz;
-      return gho;
-    }
-
   ethernet_header_t *eh = (ethernet_header_t *) vlib_buffer_get_current (b0);
   u16 ethertype = clib_net_to_host_u16 (eh->type);
   u16 l2hdr_sz = sizeof (ethernet_header_t);
diff --git a/src/vnet/gso/node.c b/src/vnet/gso/node.c
index a48a8b69a23..89520f5b7fd 100644
--- a/src/vnet/gso/node.c
+++ b/src/vnet/gso/node.c
@@ -55,17 +55,38 @@ static_always_inline u16
 tso_alloc_tx_bufs (vlib_main_t * vm,
 		   vnet_interface_per_thread_data_t * ptd,
 		   vlib_buffer_t * b0, u32 n_bytes_b0, u16 l234_sz,
-		   u16 gso_size, gso_header_offset_t * gho)
+		   u16 gso_size, u16 first_data_size,
+		   gso_header_offset_t * gho)
 {
-  u16 size =
+
+  u16 n_alloc, size;
+  u16 first_packet_length = l234_sz + first_data_size;
+
+  /*
+   * size is the amount of data per segmented buffer except the 1st
+   * segmented buffer.
+   * l2_hdr_offset is an offset == current_data of vlib_buffer_t.
+   * l234_sz is hdr_sz from l2_hdr_offset.
+   */
+  size =
     clib_min (gso_size, vlib_buffer_get_default_data_size (vm) - l234_sz
 	      - gho->l2_hdr_offset);
 
-  /* rounded-up division */
-  u16 n_bufs = (n_bytes_b0 - l234_sz + (size - 1)) / size;
-  u16 n_alloc;
+  /*
+   * First segmented buffer length is calculated separately.
+   * As it may contain less data than gso_size (when gso_size is
+   * greater than current_length of 1st buffer from GSO chained
+   * buffers) and/or size calculated above.
+   */
+  u16 n_bufs = 1;
+
+  /*
+   * Total packet length minus first packet length including l234 header.
+   * rounded-up division
+   */
+  ASSERT (n_bytes_b0 > first_packet_length);
+  n_bufs += ((n_bytes_b0 - first_packet_length + (size - 1)) / size);
 
-  ASSERT (n_bufs > 0);
   vec_validate (ptd->split_buffers, n_bufs - 1);
 
   n_alloc = vlib_buffer_alloc (vm, ptd->split_buffers, n_bufs);
@@ -126,12 +147,10 @@ tso_fixup_segmented_buf (vlib_buffer_t * b0, u8 tcp_flags, int is_ip6,
 
   if (is_ip6)
     ip6->payload_length =
-      clib_host_to_net_u16 (b0->current_length -
-			    (gho->l4_hdr_offset - gho->l2_hdr_offset));
+      clib_host_to_net_u16 (b0->current_length - gho->l4_hdr_offset);
   else
     ip4->length =
-      clib_host_to_net_u16 (b0->current_length -
-			    (gho->l3_hdr_offset - gho->l2_hdr_offset));
+      clib_host_to_net_u16 (b0->current_length - gho->l3_hdr_offset);
 }
 
 /**
@@ -166,12 +185,13 @@ tso_segment_buffer (vlib_main_t * vm, vnet_interface_per_thread_data_t * ptd,
 
   u32 default_bflags =
     sb0->flags & ~(VNET_BUFFER_F_GSO | VLIB_BUFFER_NEXT_PRESENT);
-  u16 l234_sz = gho->l4_hdr_offset + l4_hdr_sz - gho->l2_hdr_offset;
+  u16 l234_sz = gho->l4_hdr_offset + l4_hdr_sz;
   int first_data_size = clib_min (gso_size, sb0->current_length - l234_sz);
   next_tcp_seq += first_data_size;
 
   if (PREDICT_FALSE
-      (!tso_alloc_tx_bufs (vm, ptd, sb0, n_bytes_b0, l234_sz, gso_size, gho)))
+      (!tso_alloc_tx_bufs
+       (vm, ptd, sb0, n_bytes_b0, l234_sz, gso_size, first_data_size, gho)))
     return 0;
 
   vlib_buffer_t *b0 = vlib_get_buffer (vm, ptd->split_buffers[0]);
@@ -489,6 +509,7 @@ vnet_gso_node_inline (vlib_main_t * vm,
 			    {
 			      sbi0 = to_next[0] = from_seg[0];
 			      sb0 = vlib_get_buffer (vm, sbi0);
+			      ASSERT (sb0->current_length > 0);
 			      to_next += 1;
 			      from_seg += 1;
 			      n_left_to_next -= 1;
@@ -509,6 +530,7 @@ vnet_gso_node_inline (vlib_main_t * vm,
 			{
 			  sbi0 = to_next[0] = from_seg[0];
 			  sb0 = vlib_get_buffer (vm, sbi0);
+			  ASSERT (sb0->current_length > 0);
 			  to_next += 1;
 			  from_seg += 1;
 			  n_left_to_next -= 1;