Don't print warning about removing policy on startup.

The policing code attempts to delete any traffic control configuration on
startup, so that interfaces come up in a known state.  If the interface
didn't have any traffic control configuration, this would cause it to
print a couple of scary sounding warning messages.  This commit makes it
so those no longer print.

diff --git a/lib/netdev.c b/lib/netdev.c
index 9768abee9fbdadeebcda348d6c8009ee05add406..8c19d078bee038e726bdd948185fa2628aa55b2d 100644 (file)
--- a/lib/netdev.c
+++ b/lib/netdev.c
@@ -1205,7 +1205,12 @@ netdev_get_stats(const struct netdev *netdev, struct netdev_stats *stats)
 
 #define POLICE_ADD_CMD "/sbin/tc qdisc add dev %s handle ffff: ingress"
 #define POLICE_CONFIG_CMD "/sbin/tc filter add dev %s parent ffff: protocol ip prio 50 u32 match ip src 0.0.0.0/0 police rate %dkbit burst %dk mtu 65535 drop flowid :1"
-#define POLICE_DEL_CMD "/sbin/tc qdisc del dev %s handle ffff: ingress"
+/* We redirect stderr to /dev/null because we often want to remove all
+ * traffic control configuration on a port so its in a known state.  If
+ * this done when there is no such configuration, tc complains, so we just
+ * always ignore it.
+ */
+#define POLICE_DEL_CMD "/sbin/tc qdisc del dev %s handle ffff: ingress 2>/dev/null"
 
 /* Attempts to set input rate limiting (policing) policy. */
 int
@@ -1226,7 +1231,9 @@ netdev_nodev_set_policing(const char *netdev_name, uint32_t kbits_rate,
         /* xxx This should be more careful about only adding if it
          * xxx actually exists, as opposed to always deleting it. */
         snprintf(command, sizeof(command), POLICE_DEL_CMD, netdev_name);
-        system(command);
+        if (system(command) == -1) {
+            VLOG_WARN_RL(&rl, "%s: problem removing policing", netdev_name);
+        }
 
         snprintf(command, sizeof(command), POLICE_ADD_CMD, netdev_name);
         if (system(command) != 0) {
@@ -1243,9 +1250,8 @@ netdev_nodev_set_policing(const char *netdev_name, uint32_t kbits_rate,
         }
     } else {
         snprintf(command, sizeof(command), POLICE_DEL_CMD, netdev_name);
-        if (system(command) != 0) {
+        if (system(command) == -1) {
             VLOG_WARN_RL(&rl, "%s: problem removing policing", netdev_name);
-            return -1;
         }
     }