Bugfix: Remove class tc configuration after queue delete.

When removing queues from datapath, tc state was being left
at the qdisc configuration.
Add netdev_delete_class function which clears this state.

lib/netdev.c

@@ -202,6 +202,7 @@ get_ipv6_address(const char *name, struct in6_addr *in6)
                           "classid %x:%x htb rate %dkbit ceil %dkbit"
 #define COMMAND_CHANGE_CLASS "/sbin/tc class change dev %s parent %x:%x " \
                              "classid %x:%x htb rate %dkbit ceil %dkbit"
+#define COMMAND_DEL_CLASS "/sbin/tc class del dev %s parent %x:%x classid %x:%x"
 
 static int
 netdev_setup_root_class(const struct netdev *netdev, uint16_t class_id,
@@ -288,6 +289,30 @@ netdev_change_class(const struct netdev *netdev, uint16_t class_id, uint16_t rat
     return 0;
 }
 
+/** Deletes a class already defined to represent an OpenFlow queue.
+ *
+ * @param netdev the device under configuration
+ * @param class_id unique identifier for this queue.
+ * @param rate the minimum rate for this queue in kbps
+ * @return 0 on success, non-zero value when the configuration was not
+ * successful.
+ */
+int
+netdev_delete_class(const struct netdev *netdev, uint16_t class_id)
+{
+    char command[1024];
+
+    snprintf(command, sizeof(command), COMMAND_DEL_CLASS, netdev->name,
+             TC_QDISC, TC_ROOT_CLASS, TC_QDISC, class_id);
+    if (system(command) != 0) {
+        VLOG_ERR("Problem deleting class %d for device %s",class_id,
+                 netdev->name);
+        return -1;
+    }
+
+    return 0;
+}
+
 static int
 open_queue_socket(const char * name, uint16_t class_id, int * fd)
 {

lib/netdev.h

@@ -98,6 +98,7 @@ int netdev_arp_lookup(const struct netdev *, uint32_t ip, uint8_t mac[6]);
 int netdev_setup_slicing(struct netdev *, uint16_t);
 int netdev_setup_class(const struct netdev *, uint16_t , uint16_t);
 int netdev_change_class(const struct netdev *, uint16_t , uint16_t);
+int netdev_delete_class(const struct netdev *, uint16_t);
 
 void netdev_enumerate(struct svec *);
 int netdev_nodev_get_flags(const char *netdev_name, enum netdev_flags *);

udatapath/of_ext_msg.c

@@ -107,6 +107,7 @@ recv_of_exp_queue_delete(struct datapath *dp,
     if (p->netdev) {
         q = dp_lookup_queue(p,queue_id);
         if (q) {
+            netdev_delete_class(p->netdev,q->class_id);
             port_delete_queue(p,q);
         }
         else {