plugin-manager: fix loop of deferred tasks when no best plugin found

If deferring tasks until result suggested, and we never got a suggestion, the
tasks may have been left deferred in loop forever. We now remove the defer
timeout in the case of waiting for suggestion, and ensure that we cancel tasks
if the last valid probing ended without best plugin found.

src/mm-plugin-manager.c

@@ -69,6 +69,7 @@ typedef struct {
     MMPlugin *suggested_plugin;
     GSList *current;
     guint source_id;
+    gboolean defer_until_suggested;
     /* Output context */
     MMPlugin *best_plugin;
 } SupportsInfo;
@@ -176,10 +177,67 @@ suggest_supports_info_result (MMPluginManager *self,
                     mm_plugin_get_name (suggested_plugin),
                     info->name);
             info->suggested_plugin = suggested_plugin;
+
+            /* If we got a task deferred until a suggestion comes,
+             * complete it */
+            if (info->defer_until_suggested) {
+                mm_dbg ("(%s): (%s) deferred task completed, got suggested plugin",
+                        mm_plugin_get_name (suggested_plugin),
+                        info->name);
+                /* Schedule checking support, which will end the operation */
+                info->best_plugin = info->suggested_plugin;
+                info->current = NULL;
+                info->source_id = g_idle_add ((GSourceFunc)find_port_support_idle,
+                                              info);
+            }
         }
     }
 }
 
+static void
+cancel_all_deferred_supports_info (MMPluginManager *self,
+                                   const gchar *physdev_path)
+{
+    gboolean abort_cancel = FALSE;
+    SupportsInfoList *list;
+    GSList *l;
+
+    list = g_hash_table_lookup (self->priv->supports,
+                                physdev_path);
+
+    if (!list)
+        return;
+
+    /* Look for support infos on the same physical path.
+     * We need to look for tasks being deferred until suggested and count
+     * them. */
+    for (l = list->info_list;
+         l && !abort_cancel;
+         l = g_slist_next (l)) {
+        SupportsInfo *info = l->data;
+
+        if (!info->defer_until_suggested)
+            abort_cancel = TRUE;
+    }
+
+    if (abort_cancel)
+        return;
+
+    /* If all remaining tasks were deferred until suggested, we need to
+     * cancel them completely */
+
+    for (l = list->info_list; l; l = g_slist_next (l)) {
+        SupportsInfo *info = l->data;
+
+        mm_dbg ("(%s) deferred task aborted, no suggested plugin set",
+                info->name);
+        /* Schedule checking support, which will end the operation */
+        info->current = NULL;
+        info->best_plugin = NULL;
+        info->source_id = g_idle_add ((GSourceFunc)find_port_support_idle, info);
+    }
+}
+
 static void
 supports_port_ready_cb (MMPlugin *plugin,
                         GAsyncResult *result,
@@ -273,27 +331,12 @@ supports_port_ready_cb (MMPlugin *plugin,
         break;
 
     case MM_PLUGIN_SUPPORTS_PORT_DEFER_UNTIL_SUGGESTED:
-        /* We were told to defer until getting a suggested plugin, and we already
+        /* We are deferred until a suggested plugin is given. If last supports task
-         * got one here, so we're done. */
+         * of a given device is finished without finding a best plugin, this task
-        if (info->suggested_plugin) {
+         * will get finished reporting unsupported. */
-            mm_dbg ("(%s): (%s) support check finished, got suggested",
+        mm_dbg ("(%s) deferring support check until result suggested",
-                    mm_plugin_get_name (MM_PLUGIN (info->suggested_plugin)),
+                info->name);
-                    info->name);
+        info->defer_until_suggested = TRUE;
-            info->best_plugin = info->suggested_plugin;
-            info->current = NULL;
-
-            /* Schedule checking support, which will end the operation */
-            info->source_id = g_idle_add ((GSourceFunc)find_port_support_idle,
-                                          info);
-        } else {
-            mm_dbg ("(%s): (%s) deferring support check until result suggested",
-                    mm_plugin_get_name (MM_PLUGIN (info->current->data)),
-                    info->name);
-            /* Schedule checking support */
-            info->source_id = g_timeout_add_seconds (SUPPORTS_DEFER_TIMEOUT_SECS,
-                                                     (GSourceFunc)find_port_support_idle,
-                                                     info);
-        }
         break;
     }
 }
@@ -305,14 +348,17 @@ find_port_support_idle (SupportsInfo *info)
 
     /* Already checked all plugins? */
     if (!info->current) {
-        /* Report best plugin in asynchronous result (could be none)
+        /* Report best plugin in asynchronous result (could be none) */
-         * Note: plugins are not expected to be removed while these
+        if (info->best_plugin)
-         * operations are ongoing, so no issue if we don't ref/unref
+            g_simple_async_result_set_op_res_gpointer (
-         * them. */
+                info->result,
-        g_simple_async_result_set_op_res_gpointer (
+                g_object_ref (info->best_plugin),
-            info->result,
+                (GDestroyNotify)g_object_unref);
-            info->best_plugin,
+        else
-            NULL);
+            g_simple_async_result_set_op_res_gpointer (
+                info->result,
+                NULL,
+                NULL);
 
         /* We are only giving the plugin as result, so we can now safely remove
          * the supports info from the manager. Always untrack the supports info
@@ -321,13 +367,16 @@ find_port_support_idle (SupportsInfo *info)
 
         /* We are reporting a best plugin found to a port. We can now
          * 'suggest' this same plugin to other ports of the same device. */
-        if (info->best_plugin) {
+        if (info->best_plugin)
             suggest_supports_info_result (info->self,
                                           info->physdev_path,
                                           info->best_plugin);
-        }
+        /* If ending without a best plugin, we need to cancel all probing tasks
+         * that got deferred until suggested. */
+        else
+            cancel_all_deferred_supports_info (info->self,
+                                               info->physdev_path);
 
-        /* The asynchronous operation is always completed here */
         g_simple_async_result_complete (info->result);
 
         supports_info_free (info);