Interfaces of type tun are marked as NO-CARRIER when no process is
attached to them. However, this bit gets set with some delay after

For this reason, it is better to wait for the bit to settle before
starting any test, otherwise any timing influence on the test may lead
to inconsistencies due to the NO-CARRIER bit randomly being or not in
the snapshot output taken by

This patch add a 'sleep 1' command right after creation of the
interface, to give the NO-CARRIER bit a chance to settle.

This issue has been witnessed on a buildbot that is
apparently slowler than average to run the unit tests.

Signed-off-by: Antonio Quartulli <>
 tests/ | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/tests/ b/tests/
index 18799d12..97e947ab 100755
--- a/tests/
+++ b/tests/
@@ -34,6 +34,13 @@ reload_dummy()
     $RUN_SUDO $openvpn --dev $IFACE --dev-type tun --rmtun >/dev/null
     $RUN_SUDO $openvpn --dev $IFACE --dev-type tun --mktun >/dev/null
+    # it seems that tun devices will settle on NO-CARRIER while not connected 
+    # any process, but this won't happen immediately. To avoid having the
+    # NO-CARRIER bit appear in the middle of the tests - which would compromise
+    # the results - let's wait 1 sec here for it to settle.
+    sleep 1
     if [ $? -ne 0 ]; then
         echo "can't create interface $IFACE"
         exit 1

Openvpn-devel mailing list

Reply via email to