vswitchd: Introduce 'mtu_request' column in Interface.

The 'mtu_request' column can be used to set the MTU of a specific
interface.

This column is useful because it will allow changing the MTU of DPDK
devices (implemented in a future commit), which are not accessible
outside the ovs-vswitchd process, but it can be used for kernel
interfaces as well.

The current implementation of set_mtu() in netdev-dpdk is removed
because it's broken.  It will be reintroduced by a subsequent commit on
this series.

Signed-off-by: Daniele Di Proietto <diproiettod@vmware.com>
Acked-by: Ilya Maximets <i.maximets@samsung.com>

NEWS

@@ -102,6 +102,8 @@ Post-v2.5.0
    - ovs-pki: Changed message digest algorithm from SHA-1 to SHA-512 because
      SHA-1 is no longer secure and some operating systems have started to
      disable it in OpenSSL.
+   - Add 'mtu_request' column to the Interface table. It can be used to
+     configure the MTU of non-internal ports.
 
 
 v2.5.0 - 26 Feb 2016

lib/netdev-dpdk.c

@@ -1649,57 +1649,6 @@ netdev_dpdk_get_mtu(const struct netdev *netdev, int *mtup)
     return 0;
 }
 
-static int
-netdev_dpdk_set_mtu(const struct netdev *netdev, int mtu)
-{
-    struct netdev_dpdk *dev = netdev_dpdk_cast(netdev);
-    int old_mtu, err, dpdk_mtu;
-    struct dpdk_mp *old_mp;
-    struct dpdk_mp *mp;
-    uint32_t buf_size;
-
-    ovs_mutex_lock(&dpdk_mutex);
-    ovs_mutex_lock(&dev->mutex);
-    if (dev->mtu == mtu) {
-        err = 0;
-        goto out;
-    }
-
-    buf_size = dpdk_buf_size(mtu);
-    dpdk_mtu = FRAME_LEN_TO_MTU(buf_size);
-
-    mp = dpdk_mp_get(dev->socket_id, dpdk_mtu);
-    if (!mp) {
-        err = ENOMEM;
-        goto out;
-    }
-
-    rte_eth_dev_stop(dev->port_id);
-
-    old_mtu = dev->mtu;
-    old_mp = dev->dpdk_mp;
-    dev->dpdk_mp = mp;
-    dev->mtu = mtu;
-    dev->max_packet_len = MTU_TO_FRAME_LEN(dev->mtu);
-
-    err = dpdk_eth_dev_init(dev);
-    if (err) {
-        dpdk_mp_put(mp);
-        dev->mtu = old_mtu;
-        dev->dpdk_mp = old_mp;
-        dev->max_packet_len = MTU_TO_FRAME_LEN(dev->mtu);
-        dpdk_eth_dev_init(dev);
-        goto out;
-    }
-
-    dpdk_mp_put(old_mp);
-    netdev_change_seq_changed(netdev);
-out:
-    ovs_mutex_unlock(&dev->mutex);
-    ovs_mutex_unlock(&dpdk_mutex);
-    return err;
-}
-
 static int
 netdev_dpdk_get_carrier(const struct netdev *netdev, bool *carrier);
 
@@ -2995,7 +2944,7 @@ netdev_dpdk_vhost_cuse_reconfigure(struct netdev *netdev)
     netdev_dpdk_set_etheraddr,                                \
     netdev_dpdk_get_etheraddr,                                \
     netdev_dpdk_get_mtu,                                      \
-    netdev_dpdk_set_mtu,                                      \
+    NULL,                       /* set_mtu */                 \
     netdev_dpdk_get_ifindex,                                  \
     GET_CARRIER,                                              \
     netdev_dpdk_get_carrier_resets,                           \

vswitchd/bridge.c

@@ -775,6 +775,15 @@ bridge_delete_or_reconfigure_ports(struct bridge *br)
             goto delete;
         }
 
+        if (iface->cfg->n_mtu_request == 1
+            && strcmp(iface->type,
+                      ofproto_port_open_type(br->type, "internal"))) {
+            /* Try to set the MTU to the requested value.  This is not done
+             * for internal interfaces, since their MTU is decided by the
+             * ofproto module, based on other ports in the bridge. */
+            netdev_set_mtu(iface->netdev, *iface->cfg->mtu_request);
+        }
+
         /* If the requested OpenFlow port for 'iface' changed, and it's not
          * already the correct port, then we might want to temporarily delete
          * this interface, so we can add it back again with the new OpenFlow

vswitchd/vswitch.ovsschema

@@ -1,6 +1,6 @@
 {"name": "Open_vSwitch",
- "version": "7.13.0",
+ "version": "7.14.0",
- "cksum": "889248633 22774",
+ "cksum": "3974332717 22936",
  "tables": {
    "Open_vSwitch": {
      "columns": {
@@ -321,6 +321,12 @@
        "mtu": {
          "type": {"key": "integer", "min": 0, "max": 1},
          "ephemeral": true},
+       "mtu_request": {
+         "type": {
+           "key": {"type": "integer",
+                   "minInteger": 1},
+           "min": 0,
+           "max": 1}},
        "error": {
          "type": {"key": "string", "min": 0, "max": 1}}},
      "indexes": [["name"]]},

vswitchd/vswitch.xml

@@ -2380,6 +2380,44 @@
       </column>
     </group>
 
+    <group title="MTU">
+      <p>
+        The MTU (maximum transmission unit) is the largest amount of data
+        that can fit into a single Ethernet frame.  The standard Ethernet
+        MTU is 1500 bytes.  Some physical media and many kinds of virtual
+        interfaces can be configured with higher MTUs.
+      </p>
+
+      <p>
+        A client may change a non-internal interface MTU by filling in
+        <ref column="mtu_request"/>.  Internal interfaces MTU, instead, is set
+        by Open vSwitch to the minimum of non-internal interfaces MTU in the
+        bridge. In any case, Open vSwitch then reports in <ref column="mtu"/>
+        the currently configured value.
+      </p>
+
+      <column name="mtu">
+        <p>
+          This column will be empty for an interface that does not
+          have an MTU as, for example, some kinds of tunnels do not.
+        </p>
+
+        <p>
+          Open vSwitch sets this column's value, so other clients should treat
+          it as read-only.
+        </p>
+      </column>
+
+      <column name="mtu_request"
+              type='{"type": "integer", "minInteger": 1}'>
+        <p>
+          Requested MTU (Maximum Transmission Unit) for the interface. A client
+          can fill this column to change the MTU of a non-internal interface.
+        </p>
+    </column>
+
+    </group>
+
     <group title="Interface Status">
       <p>
         Status information about interfaces attached to bridges, updated every
@@ -2422,20 +2460,6 @@
         </p>
       </column>
 
-      <column name="mtu">
-        <p>
-          The MTU (maximum transmission unit); i.e. the largest
-          amount of data that can fit into a single Ethernet frame.
-          The standard Ethernet MTU is 1500 bytes.  Some physical media
-          and many kinds of virtual interfaces can be configured with
-          higher MTUs.
-        </p>
-        <p>
-          This column will be empty for an interface that does not
-          have an MTU as, for example, some kinds of tunnels do not.
-        </p>
-      </column>
-
       <column name="lacp_current">
         Boolean value indicating LACP status for this interface.  If true, this
         interface has current LACP information about its LACP partner.  This