Improve NTP / kernel time change event handling

clib_time_verify_frequency(...) rejects clock frequency changes
greater than 1%.

vlib_worker_thread_barrier_sync_int (...) continuously checks that the
barrier hold-down timer is not unreasonably far in the future.

Change-Id: I00ecb4c20e44de5d6a9c1499fa933e3dd834d11a
Signed-off-by: Dave Barach <dbarach@cisco.com>

1 files changed, 14 insertions, 2 deletions

diff --git a/src/vlib/threads.c b/src/vlib/threads.c
index 8e75592c0e2..1972886a78b 100644
--- a/src/vlib/threads.c
+++ b/src/vlib/threads.c
@@ -1466,9 +1466,21 @@ vlib_worker_thread_barrier_sync_int (vlib_main_t * vm)
 
   /* Enforce minimum barrier open time to minimize packet loss */
   ASSERT (vm->barrier_no_close_before <= (now + BARRIER_MINIMUM_OPEN_LIMIT));
-  while ((now = vlib_time_now (vm)) < vm->barrier_no_close_before)
-    ;
 
+  while (1)
+    {
+      now = vlib_time_now (vm);
+      /* Barrier hold-down timer expired? */
+      if (now >= vm->barrier_no_close_before)
+	break;
+      if ((vm->barrier_no_close_before - now)
+	  > (2.0 * BARRIER_MINIMUM_OPEN_LIMIT))
+	{
+	  clib_warning ("clock change: would have waited for %.4f seconds",
+			(vm->barrier_no_close_before - now));
+	  break;
+	}
+    }
   /* Record time of closure */
   t_open = now - vm->barrier_epoch;
   vm->barrier_epoch = now;