netdev-linux: Add new QoS type linux-noop.

Linux ``No operation'' qos type is used to inform the vswitch that the
traffic control for the port is managed externally. Any configuration values
set for this type will have no effect.

This patch provides a solution suggested in this mail -
http://openvswitch.org/pipermail/discuss/2015-May/017687.html

Signed-off-by: Babu Shanmugam <bschanmu@redhat.com>
Signed-off-by: Ben Pfaff <blp@ovn.org>

NEWS

@@ -23,6 +23,9 @@ Post-v2.5.0
      * New option "--color" to produce colorized output for some commands.
      * New commands "dump-ipfix-bridge" and "dump-ipfix-flow" to dump bridge
        IPFIX statistics and flow based IPFIX statistics.
+   - Linux:
+     * New QoS type "linux-noop" that prevents Open vSwitch from trying to
+       manage QoS for a given port (useful when other software manages QoS).
    - DPDK:
      * New option "n_rxq" for PMD interfaces.
        Old 'other_config:n-dpdk-rxqs' is no longer supported.

lib/netdev-linux.c

@@ -418,6 +418,7 @@ static const struct tc_ops tc_ops_codel;
 static const struct tc_ops tc_ops_fqcodel;
 static const struct tc_ops tc_ops_sfq;
 static const struct tc_ops tc_ops_default;
+static const struct tc_ops tc_ops_noop;
 static const struct tc_ops tc_ops_other;
 
 static const struct tc_ops *const tcs[] = {
@@ -426,6 +427,7 @@ static const struct tc_ops *const tcs[] = {
     &tc_ops_codel,              /* Controlled delay */
     &tc_ops_fqcodel,            /* Fair queue controlled delay */
     &tc_ops_sfq,                /* Stochastic fair queueing */
+    &tc_ops_noop,               /* Non operating qos type. */
     &tc_ops_default,            /* Default qdisc (see tc-pfifo_fast(8)). */
     &tc_ops_other,              /* Some other qdisc. */
     NULL
@@ -2101,7 +2103,6 @@ netdev_linux_get_qos_types(const struct netdev *netdev OVS_UNUSED,
                            struct sset *types)
 {
     const struct tc_ops *const *opsp;
-
     for (opsp = tcs; *opsp != NULL; opsp++) {
         const struct tc_ops *ops = *opsp;
         if (ops->tc_install && ops->ovs_name[0] != '\0') {
@@ -2206,6 +2207,10 @@ netdev_linux_set_qos(struct netdev *netdev_,
         return EOPNOTSUPP;
     }
 
+    if (new_ops == &tc_ops_noop) {
+        return new_ops->tc_install(netdev_, details);
+    }
+
     ovs_mutex_lock(&netdev->mutex);
     error = tc_query_qdisc(netdev_);
     if (error) {
@@ -4489,6 +4494,48 @@ static const struct tc_ops tc_ops_hfsc = {
     hfsc_class_dump_stats       /* class_dump_stats */
 };
 
+/* "linux-noop" traffic control class. */
+
+static void
+noop_install__(struct netdev *netdev_)
+{
+    struct netdev_linux *netdev = netdev_linux_cast(netdev_);
+    static const struct tc tc = TC_INITIALIZER(&tc, &tc_ops_default);
+
+    netdev->tc = CONST_CAST(struct tc *, &tc);
+}
+
+static int
+noop_tc_install(struct netdev *netdev,
+                   const struct smap *details OVS_UNUSED)
+{
+    noop_install__(netdev);
+    return 0;
+}
+
+static int
+noop_tc_load(struct netdev *netdev, struct ofpbuf *nlmsg OVS_UNUSED)
+{
+    noop_install__(netdev);
+    return 0;
+}
+
+static const struct tc_ops tc_ops_noop = {
+    NULL,                       /* linux_name */
+    "linux-noop",               /* ovs_name */
+    0,                          /* n_queues */
+    noop_tc_install,
+    noop_tc_load,
+    NULL,                       /* tc_destroy */
+    NULL,                       /* qdisc_get */
+    NULL,                       /* qdisc_set */
+    NULL,                       /* class_get */
+    NULL,                       /* class_set */
+    NULL,                       /* class_delete */
+    NULL,                       /* class_get_stats */
+    NULL                        /* class_dump_stats */
+};
+
 /* "linux-default" traffic control class.
  *
  * This class represents the default, unnamed Linux qdisc.  It corresponds to

vswitchd/vswitch.xml

@@ -3350,16 +3350,14 @@
           (<code>http://luxik.cdi.cz/~devik/qos/htb/manual/userg.htm</code>)
           for information on how this classifier works and how to configure it.
         </dd>
-      </dl>
+
-      <dl>
         <dt><code>linux-hfsc</code></dt>
         <dd>
           Linux "Hierarchical Fair Service Curve" classifier.
           See <code>http://linux-ip.net/articles/hfsc.en/</code> for
           information on how this classifier works.
         </dd>
-      </dl>
+
-      <dl>
         <dt><code>linux-sfq</code></dt>
         <dd>
           Linux ``Stochastic Fairness Queueing'' classifier. See
@@ -3367,8 +3365,7 @@
           <code>http://linux.die.net/man/8/tc-sfq</code>) for information on
           how this classifier works.
         </dd>
-      </dl>
+
-      <dl>
         <dt><code>linux-codel</code></dt>
         <dd>
           Linux ``Controlled Delay'' classifier. See <code>tc-codel</code>(8)
@@ -3376,8 +3373,7 @@
           <code>http://man7.org/linux/man-pages/man8/tc-codel.8.html</code>)
           for information on how this classifier works.
         </dd>
-      </dl>
+
-      <dl>
         <dt><code>linux-fq_codel</code></dt>
         <dd>
           Linux ``Fair Queuing with Controlled Delay'' classifier. See
@@ -3385,11 +3381,19 @@
           <code>http://man7.org/linux/man-pages/man8/tc-fq_codel.8.html</code>)
           for information on how this classifier works.
         </dd>
-      </dl>
+
-      <dl>
+        <dt><code>linux-noop</code></dt>
+        <dd>
+          Linux ``No operation.''  By default, Open vSwitch manages quality of
+          service on all of its configured ports.  This can be helpful, but
+          sometimes administrators prefer to use other software to manage QoS.
+          This <ref column="type"/> prevents Open vSwitch from changing the QoS
+          configuration for a port.
+        </dd>
+
         <dt><code>egress-policer</code></dt>
         <dd>
-          An egress policer algorithm. This implementation uses the DPDK
+          A DPDK egress policer algorithm using the DPDK
           rte_meter library. The rte_meter library provides an implementation
           which allows the metering and policing of traffic. The implementation
           in OVS essentially creates a single token bucket used to police