ipsec: Store thread-index in buffer meta-data during SA handoff

Type: improvement

negates the need to load the SA in the handoff node.
don't prefetch the packet data, it's not needed.

Signed-off-by: Neale Ranns <neale@graphiant.com>
Change-Id: I340472dc437f050cc1c3c11dfeb47ab09c609624
diff --git a/src/vnet/ipsec/esp_encrypt.c b/src/vnet/ipsec/esp_encrypt.c
index e64de26..c76fccc 100644
--- a/src/vnet/ipsec/esp_encrypt.c
+++ b/src/vnet/ipsec/esp_encrypt.c
@@ -685,6 +685,7 @@
 
       if (PREDICT_FALSE (thread_index != sa0->thread_index))
 	{
+	  vnet_buffer (b[0])->ipsec.thread_index = sa0->thread_index;
 	  esp_set_next_index (is_async, from, nexts, from[b - bufs],
 			      &n_async_drop, handoff_next, next);
 	  goto trace;