dpif-netdev: Use netdev-offload API for port lookup while offloading.

Currently, while offloading, userspace datapath tries to lookup netdev
in a local port list of the datapath interface instance.  However,
there is no guarantee that these netdevs are the same netdevs that
netdev-offload module operates with and, as a result, there is no any
guarantee that these netdev instances has initialized flow API.

dpif-netdev should request ports from the netdev-offload module as
intended by flow offloading API in a same way as dpif-netlink does.
This will also give us performance benefits because we don't need to
hold global port mutex anymore.

We're not noticing any significant issues with current code, but
it will become a serious issue in the future, e.g. with offloading
for virtual tunneling ports.

Reported-by: Ophir Munk <[email protected]>
Fixes: 241bad1 ("dpif-netdev: associate flow with a mark id")
Signed-off-by: Ilya Maximets <[email protected]>
Acked-by: Ophir Munk <[email protected]>
Acked-by: Eli Britstein <[email protected]>

lib/dpif-netdev.c

@@ -2266,15 +2266,14 @@ mark_to_flow_disassociate(struct dp_netdev_pmd_thread *pmd,
      * remove the flow from hardware and free the mark.
      */
     if (flow_mark_has_no_ref(mark)) {
-        struct dp_netdev_port *port;
+        struct netdev *port;
         odp_port_t in_port = flow->flow.in_port.odp_port;
 
-        ovs_mutex_lock(&pmd->dp->port_mutex);
-        port = dp_netdev_lookup_port(pmd->dp, in_port);
+        port = netdev_ports_get(in_port, pmd->dp->dpif->dpif_class);
         if (port) {
-            ret = netdev_flow_del(port->netdev, &flow->mega_ufid, NULL);
+            ret = netdev_flow_del(port, &flow->mega_ufid, NULL);
+            netdev_close(port);
         }
-        ovs_mutex_unlock(&pmd->dp->port_mutex);
 
         flow_mark_free(mark);
         VLOG_DBG("Freed flow mark %u\n", mark);
@@ -2372,12 +2371,12 @@ dp_netdev_flow_offload_del(struct dp_flow_offload_item *offload)
 static int
 dp_netdev_flow_offload_put(struct dp_flow_offload_item *offload)
 {
-    struct dp_netdev_port *port;
     struct dp_netdev_pmd_thread *pmd = offload->pmd;
     struct dp_netdev_flow *flow = offload->flow;
     odp_port_t in_port = flow->flow.in_port.odp_port;
     bool modification = offload->op == DP_NETDEV_FLOW_OFFLOAD_OP_MOD;
     struct offload_info info;
+    struct netdev *port;
     uint32_t mark;
     int ret;
 
@@ -2411,17 +2410,16 @@ dp_netdev_flow_offload_put(struct dp_flow_offload_item *offload)
     }
     info.flow_mark = mark;
 
-    ovs_mutex_lock(&pmd->dp->port_mutex);
-    port = dp_netdev_lookup_port(pmd->dp, in_port);
-    if (!port || netdev_vport_is_vport_class(port->netdev->netdev_class)) {
-        ovs_mutex_unlock(&pmd->dp->port_mutex);
+    port = netdev_ports_get(in_port, pmd->dp->dpif->dpif_class);
+    if (!port || netdev_vport_is_vport_class(port->netdev_class)) {
+        netdev_close(port);
         goto err_free;
     }
-    ret = netdev_flow_put(port->netdev, &offload->match,
+    ret = netdev_flow_put(port, &offload->match,
                           CONST_CAST(struct nlattr *, offload->actions),
                           offload->actions_len, &flow->mega_ufid, &info,
                           NULL);
-    ovs_mutex_unlock(&pmd->dp->port_mutex);
+    netdev_close(port);
 
     if (ret) {
         goto err_free;