ovs: clean up interfaces from ovsdb at startup

During shutdown, NM always tries to remove from ovsdb all bridges,
ports, interfaces that it previously added. Currently NM doesn't run
the main loop during shutdown and so it's not possible to perform
asynchronous operations. In particular, the NMOvsdb singleton is
disposed in a destructor where it's not possible to send out all the
queued deletions.

The result is that NM deletes only one OVS interface, keeping the
others. This needs to be fixed, but requires a rework of the shutdown
procedure that involves many parts of NM.

Even when a better shutdown procedure will be implemented, we should
support an unclean shutdown caused by e.g. a kernel panic or a NM
crash. In these cases, the interfaces added by NM would still linger
in the ovsdb.

Delete all those interface at NM startup. If there are connections
profiles for them, NM will create them again.

Also, NMOvsdb now emits a NM_OVSDB_READY signal and provides a
nm_ovsdb_is_ready() to allow other parts of the daemon to order
actions after the initial OVS cleanup.

https://bugzilla.redhat.com/show_bug.cgi?id=1861296
https://gitlab.freedesktop.org/NetworkManager/NetworkManager/-/merge_requests/700

src/devices/ovs/nm-ovsdb.c

@@ -106,7 +106,13 @@ typedef struct {
 
 /*****************************************************************************/
 
-enum { DEVICE_ADDED, DEVICE_REMOVED, INTERFACE_FAILED, LAST_SIGNAL };
+enum {
+    DEVICE_ADDED,
+    DEVICE_REMOVED,
+    INTERFACE_FAILED,
+    READY,
+    LAST_SIGNAL,
+};
 
 static guint signals[LAST_SIGNAL] = {0};
 
@@ -127,6 +133,8 @@ typedef struct {
     GHashTable *bridges;    /* bridge uuid => OpenvswitchBridge */
     char *      db_uuid;
     guint       num_failures;
+    guint       num_pending_deletions;
+    bool        ready : 1;
 } NMOvsdbPrivate;
 
 struct _NMOvsdb {
@@ -2219,6 +2227,9 @@ ovsdb_disconnect(NMOvsdb *self, gboolean retry, gboolean is_disposing)
 
     _LOGD("disconnecting from ovsdb, retry %d", retry);
 
+    /* FIXME(shutdown): NMOvsdb should process the pending calls before
+     * shutting down, and cancel the remaining calls after the timeout. */
+
     if (retry) {
         if (!c_list_is_empty(&priv->calls_lst_head)) {
             call          = c_list_first_entry(&priv->calls_lst_head, OvsdbMethodCall, calls_lst);
@@ -2247,6 +2258,75 @@ ovsdb_disconnect(NMOvsdb *self, gboolean retry, gboolean is_disposing)
         ovsdb_try_connect(self);
 }
 
+static void
+_check_ready(NMOvsdb *self)
+{
+    NMOvsdbPrivate *priv = NM_OVSDB_GET_PRIVATE(self);
+
+    nm_assert(!priv->ready);
+
+    if (priv->num_pending_deletions == 0) {
+        priv->ready = TRUE;
+        g_signal_emit(self, signals[READY], 0);
+    }
+}
+
+static void
+_del_initial_iface_cb(GError *error, gpointer user_data)
+{
+    NMOvsdb *       self;
+    gs_free char *  ifname = NULL;
+    NMOvsdbPrivate *priv;
+
+    nm_utils_user_data_unpack(user_data, &self, &ifname);
+
+    if (nm_utils_error_is_cancelled_or_disposing(error))
+        return;
+
+    priv = NM_OVSDB_GET_PRIVATE(self);
+    nm_assert(priv->num_pending_deletions > 0);
+    priv->num_pending_deletions--;
+
+    _LOGD("delete initial interface '%s': %s %s%s%s, pending %u",
+          ifname,
+          error ? "error" : "success",
+          error ? "(" : "",
+          error ? error->message : "",
+          error ? ")" : "",
+          priv->num_pending_deletions);
+
+    _check_ready(self);
+}
+
+static void
+ovsdb_cleanup_initial_interfaces(NMOvsdb *self)
+{
+    NMOvsdbPrivate *            priv = NM_OVSDB_GET_PRIVATE(self);
+    const OpenvswitchInterface *interface;
+    NMUtilsUserData *           data;
+    GHashTableIter              iter;
+
+    if (priv->ready || priv->num_pending_deletions != 0)
+        return;
+
+    /* Delete OVS interfaces added by NM. Bridges and ports and
+     * not considered because they are deleted automatically
+     * when no interface is present. */
+    g_hash_table_iter_init(&iter, self->_priv.interfaces);
+    while (g_hash_table_iter_next(&iter, NULL, (gpointer *) &interface)) {
+        if (interface->connection_uuid) {
+            priv->num_pending_deletions++;
+            _LOGD("deleting initial interface '%s' (pending: %u)",
+                  interface->name,
+                  priv->num_pending_deletions);
+            data = nm_utils_user_data_pack(self, g_strdup(interface->name));
+            nm_ovsdb_del_interface(self, interface->name, _del_initial_iface_cb, data);
+        }
+    }
+
+    _check_ready(self);
+}
+
 static void
 _monitor_bridges_cb(NMOvsdb *self, json_t *result, GError *error, gpointer user_data)
 {
@@ -2261,6 +2341,8 @@ _monitor_bridges_cb(NMOvsdb *self, json_t *result, GError *error, gpointer user_
     /* Treat the first response the same as the subsequent "update"
      * messages we eventually get. */
     ovsdb_got_update(self, result);
+
+    ovsdb_cleanup_initial_interfaces(self);
 }
 
 static void
@@ -2380,6 +2462,14 @@ ovsdb_call_new(NMOvsdbCallback callback, gpointer user_data)
     return call;
 }
 
+gboolean
+nm_ovsdb_is_ready(NMOvsdb *self)
+{
+    NMOvsdbPrivate *priv = NM_OVSDB_GET_PRIVATE(self);
+
+    return priv->ready;
+}
+
 void
 nm_ovsdb_add_interface(NMOvsdb *       self,
                        NMConnection *  bridge,
@@ -2553,4 +2643,14 @@ nm_ovsdb_class_init(NMOvsdbClass *klass)
                                              G_TYPE_STRING,
                                              G_TYPE_STRING,
                                              G_TYPE_STRING);
+
+    signals[READY] = g_signal_new(NM_OVSDB_READY,
+                                  G_OBJECT_CLASS_TYPE(object_class),
+                                  G_SIGNAL_RUN_LAST,
+                                  0,
+                                  NULL,
+                                  NULL,
+                                  NULL,
+                                  G_TYPE_NONE,
+                                  0);
 }

src/devices/ovs/nm-ovsdb.h

@@ -16,6 +16,7 @@
 #define NM_OVSDB_DEVICE_ADDED     "device-added"
 #define NM_OVSDB_DEVICE_REMOVED   "device-removed"
 #define NM_OVSDB_INTERFACE_FAILED "interface-failed"
+#define NM_OVSDB_READY            "ready"
 
 typedef struct _NMOvsdb      NMOvsdb;
 typedef struct _NMOvsdbClass NMOvsdbClass;
@@ -55,4 +56,6 @@ void nm_ovsdb_set_external_ids(NMOvsdb *                        self,
                                struct _NMSettingOvsExternalIDs *s_exid_old,
                                struct _NMSettingOvsExternalIDs *s_exid_new);
 
+gboolean nm_ovsdb_is_ready(NMOvsdb *self);
+
 #endif /* __NETWORKMANAGER_OVSDB_H__ */