selftests: forwarding: Move lldpad waiting to lib.sh

The function lldpad_wait() will be useful for a test added by a
following patch. Likewise would the "sleep 5" with its extensive
comment.

Therefore move lldpad_wait() to lib.sh in order to allow reuse. Rename
it to lldpad_app_wait_set() to recognize that what this is intended to
wait on are the pending APP sets.

For the sleeping, add a function lldpad_app_wait_del(). That will serve
to hold the related explanatory comment (which edit for clarity), and as
a token in the caller to identify the sites where this sort of waiting
takes place. That will serve when/if a better way to handle this
business is found.

Signed-off-by: Petr Machata <petrm@mellanox.com>
Reviewed-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

tools/testing/selftests/net/forwarding/lib.sh

@@ -247,6 +247,27 @@ setup_wait()
 	sleep $WAIT_TIME
 }
 
+lldpad_app_wait_set()
+{
+	local dev=$1; shift
+
+	while lldptool -t -i $dev -V APP -c app | grep -q pending; do
+		echo "$dev: waiting for lldpad to push pending APP updates"
+		sleep 5
+	done
+}
+
+lldpad_app_wait_del()
+{
+	# Give lldpad a chance to push down the changes. If the device is downed
+	# too soon, the updates will be left pending. However, they will have
+	# been struck off the lldpad's DB already, so we won't be able to tell
+	# they are pending. Then on next test iteration this would cause
+	# weirdness as newly-added APP rules conflict with the old ones,
+	# sometimes getting stuck in an "unknown" state.
+	sleep 5
+}
+
 pre_cleanup()
 {
 	if [ "${PAUSE_ON_CLEANUP}" = "yes" ]; then