vnet: clean up calc_checksums()

Remove the duplicated code and unnecessary operations.

Change-Id: I78005848d29d3156165627926a79015d590d61a6
Signed-off-by: Zhiyong Yang <zhiyong.yang@intel.com>

diff --git a/src/vnet/interface_output.c b/src/vnet/interface_output.c
index 698c6e1..57eea0f 100644 (file)
--- a/src/vnet/interface_output.c
+++ b/src/vnet/interface_output.c
@@ -179,8 +179,6 @@ vnet_interface_output_trace (vlib_main_t * vm,
 static_always_inline void
 calc_checksums (vlib_main_t * vm, vlib_buffer_t * b)
 {
-  ip4_header_t *ip4;
-  ip6_header_t *ip6;
   tcp_header_t *th;
   udp_header_t *uh;
 
@@ -189,13 +187,13 @@ calc_checksums (vlib_main_t * vm, vlib_buffer_t * b)
 
   ASSERT (!(is_ip4 && is_ip6));
 
-  ip4 = (ip4_header_t *) (b->data + vnet_buffer (b)->l3_hdr_offset);
-  ip6 = (ip6_header_t *) (b->data + vnet_buffer (b)->l3_hdr_offset);
   th = (tcp_header_t *) (b->data + vnet_buffer (b)->l4_hdr_offset);
   uh = (udp_header_t *) (b->data + vnet_buffer (b)->l4_hdr_offset);
 
   if (is_ip4)
     {
+      ip4_header_t *ip4;
+
       ip4 = (ip4_header_t *) (b->data + vnet_buffer (b)->l3_hdr_offset);
       if (b->flags & VNET_BUFFER_F_OFFLOAD_IP_CKSUM)
        ip4->checksum = ip4_header_checksum (ip4);
@@ -204,19 +202,22 @@ calc_checksums (vlib_main_t * vm, vlib_buffer_t * b)
          th->checksum = 0;
          th->checksum = ip4_tcp_udp_compute_checksum (vm, b, ip4);
        }
-      if (b->flags & VNET_BUFFER_F_OFFLOAD_UDP_CKSUM)
+      else if (b->flags & VNET_BUFFER_F_OFFLOAD_UDP_CKSUM)
        uh->checksum = ip4_tcp_udp_compute_checksum (vm, b, ip4);
     }
-  if (is_ip6)
+  else if (is_ip6)
     {
       int bogus;
+      ip6_header_t *ip6;
+
+      ip6 = (ip6_header_t *) (b->data + vnet_buffer (b)->l3_hdr_offset);
       if (b->flags & VNET_BUFFER_F_OFFLOAD_TCP_CKSUM)
        {
          th->checksum = 0;
          th->checksum =
            ip6_tcp_udp_icmp_compute_checksum (vm, b, ip6, &bogus);
        }
-      if (b->flags & VNET_BUFFER_F_OFFLOAD_UDP_CKSUM)
+      else if (b->flags & VNET_BUFFER_F_OFFLOAD_UDP_CKSUM)
        {
          uh->checksum = 0;
          uh->checksum =