datapath: Make adding and attaching a vport a single step.

For some time now, Open vSwitch datapaths have internally made a
distinction between adding a vport and attaching it to a datapath.  Adding
a vport just means to create it, as an entity detached from any datapath.
Attaching it gives it a port number and a datapath.  Similarly, a vport
could be detached and deleted separately.

After some study, I think I understand why this distinction exists.  It is
because ovs-vswitchd tries to open all the datapath ports before it tries
to create them.  However, changing it to create them before it tries to
open them is not difficult, so this commit does this.

The bulk of this commit, however, changes the datapath interface to one
that always creates a vport and attaches it to a datapath in a single step,
and similarly detaches a vport and deletes it in a single step.

Signed-off-by: Ben Pfaff <blp@nicira.com>
Acked-by: Jesse Gross <jesse@nicira.com>

1 files changed, 19 insertions, 27 deletions

diff --git a/lib/netdev.c b/lib/netdev.c
index d108e9ca8..c7de9064b 100644
--- a/lib/netdev.c
+++ b/lib/netdev.c
@@ -75,6 +75,7 @@ netdev_initialize(void)
 
 #ifdef HAVE_NETLINK
         netdev_register_provider(&netdev_linux_class);
+        netdev_register_provider(&netdev_internal_class);
         netdev_register_provider(&netdev_tap_class);
         netdev_vport_register();
 #endif
@@ -167,6 +168,13 @@ netdev_unregister_provider(const char *type)
     return 0;
 }
 
+const struct netdev_class *
+netdev_lookup_provider(const char *type)
+{
+    netdev_initialize();
+    return shash_find_data(&netdev_classes, type && type[0] ? type : "system");
+}
+
 /* Clears 'types' and enumerates the types of all currently registered netdev
  * providers into it.  The caller must first initialize the svec. */
 void
@@ -252,28 +260,6 @@ update_device_args(struct netdev_dev *dev, const struct shash *args)
     qsort(dev->args, dev->n_args, sizeof *dev->args, compare_args);
 }
 
-static int
-create_device(struct netdev_options *options, struct netdev_dev **netdev_devp)
-{
-    struct netdev_class *netdev_class;
-    int error;
-
-    if (!options->type || strlen(options->type) == 0) {
-        /* Default to system. */
-        options->type = "system";
-    }
-
-    netdev_class = shash_find_data(&netdev_classes, options->type);
-    if (!netdev_class) {
-        return EAFNOSUPPORT;
-    }
-
-    error = netdev_class->create(netdev_class, options->name, options->args,
-                                 netdev_devp);
-    assert(error || (*netdev_devp)->netdev_class == netdev_class);
-    return error;
-}
-
 /* Opens the network device named 'name' (e.g. "eth0") and returns zero if
  * successful, otherwise a positive errno value.  On success, sets '*netdevp'
  * to the new network device, otherwise to null.
@@ -302,14 +288,20 @@ netdev_open(struct netdev_options *options, struct netdev **netdevp)
     netdev_dev = shash_find_data(&netdev_dev_shash, options->name);
 
     if (!netdev_dev) {
-        error = create_device(options, &netdev_dev);
+        const struct netdev_class *class;
+
+        class = netdev_lookup_provider(options->type);
+        if (!class) {
+            VLOG_WARN("could not create netdev %s of unknown type %s",
+                      options->name, options->type);
+            return EAFNOSUPPORT;
+        }
+        error = class->create(class, options->name, options->args,
+                              &netdev_dev);
         if (error) {
-            if (error == EAFNOSUPPORT) {
-                VLOG_WARN("could not create netdev %s of unknown type %s",
-                          options->name, options->type);
-            }
             return error;
         }
+        assert(netdev_dev->netdev_class == class);
         update_device_args(netdev_dev, options->args);
 
     } else if (!shash_is_empty(options->args) &&